Adding upstream version 0.70.1+ds1.upstream/0.70.1+ds1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

22 files changed, 19988 insertions, 0 deletions

diff --git a/vendor/hashbrown/src/external_trait_impls/mod.rs b/vendor/hashbrown/src/external_trait_impls/mod.rs
new file mode 100644
index 0000000..01d386b
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/mod.rs
@@ -0,0 +1,6 @@
+#[cfg(feature = "rayon")]
+pub(crate) mod rayon;
+#[cfg(feature = "rkyv")]
+mod rkyv;
+#[cfg(feature = "serde")]
+mod serde;
diff --git a/vendor/hashbrown/src/external_trait_impls/rayon/helpers.rs b/vendor/hashbrown/src/external_trait_impls/rayon/helpers.rs
new file mode 100644
index 0000000..070b08c
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/helpers.rs
@@ -0,0 +1,27 @@
+use alloc::collections::LinkedList;
+use alloc::vec::Vec;
+
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+
+/// Helper for collecting parallel iterators to an intermediary
+#[allow(clippy::linkedlist)] // yes, we need linked list here for efficient appending!
+pub(super) fn collect<I: IntoParallelIterator>(iter: I) -> (LinkedList<Vec<I::Item>>, usize) {
+    let list = iter
+        .into_par_iter()
+        .fold(Vec::new, |mut vec, elem| {
+            vec.push(elem);
+            vec
+        })
+        .map(|vec| {
+            let mut list = LinkedList::new();
+            list.push_back(vec);
+            list
+        })
+        .reduce(LinkedList::new, |mut list1, mut list2| {
+            list1.append(&mut list2);
+            list1
+        });
+
+    let len = list.iter().map(Vec::len).sum();
+    (list, len)
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rayon/map.rs b/vendor/hashbrown/src/external_trait_impls/rayon/map.rs
new file mode 100644
index 0000000..2534dc9
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/map.rs
@@ -0,0 +1,721 @@
+//! Rayon extensions for `HashMap`.
+
+use super::raw::{RawIntoParIter, RawParDrain, RawParIter};
+use crate::hash_map::HashMap;
+use crate::raw::{Allocator, Global};
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use core::marker::PhantomData;
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+
+/// Parallel iterator over shared references to entries in a map.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashMap.html#method.par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParIter<'a, K, V> {
+    type Item = (&'a K, &'a V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_ref();
+                (&r.0, &r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParIter<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIter<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe {
+            let r = x.as_ref();
+            (&r.0, &r.1)
+        });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to keys in a map.
+///
+/// This iterator is created by the [`par_keys`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_keys`]: /hashbrown/struct.HashMap.html#method.par_keys
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParKeys<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParKeys<'a, K, V> {
+    type Item = &'a K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().0 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParKeys<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V> fmt::Debug for ParKeys<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().0 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to values in a map.
+///
+/// This iterator is created by the [`par_values`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values`]: /hashbrown/struct.HashMap.html#method.par_values
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValues<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParValues<'a, K, V> {
+    type Item = &'a V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParValues<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValues<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().1 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over mutable references to entries in a map.
+///
+/// This iterator is created by the [`par_iter_mut`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefMutIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter_mut`]: /hashbrown/struct.HashMap.html#method.par_iter_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefMutIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefMutIterator.html
+pub struct ParIterMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParIterMut<'a, K, V> {
+    type Item = (&'a K, &'a mut V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_mut();
+                (&r.0, &mut r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIterMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over mutable references to values in a map.
+///
+/// This iterator is created by the [`par_values_mut`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values_mut`]: /hashbrown/struct.HashMap.html#method.par_values_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValuesMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParValuesMut<'a, K, V> {
+    type Item = &'a mut V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &mut x.as_mut().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValuesMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParValues {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over entries of a consumed map.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashMap.html#method.into_par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<K, V, A: Allocator = Global> {
+    inner: RawIntoParIter<(K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Send> ParallelIterator for IntoParIter<K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel draining iterator over entries of a map.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashMap.html#method.par_drain
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParDrain<'a, K, V, A: Allocator = Global> {
+    inner: RawParDrain<'a, (K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+impl<K: Sync, V: Sync, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) immutably borrowed keys in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_keys(&self) -> ParKeys<'_, K, V> {
+        ParKeys {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Visits (potentially in parallel) immutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values(&self) -> ParValues<'_, K, V> {
+        ParValues {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) mutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values_mut(&mut self) -> ParValuesMut<'_, K, V> {
+        ParValuesMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the map's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, K, V, A> {
+        ParDrain {
+            inner: self.table.par_drain(),
+        }
+    }
+}
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Sync,
+    V: PartialEq + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    /// Returns `true` if the map is equal to another,
+    /// i.e. both maps contain the same keys mapped to the same values.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_eq(&self, other: &Self) -> bool {
+        self.len() == other.len()
+            && self
+                .into_par_iter()
+                .all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator + Send> IntoParallelIterator for HashMap<K, V, S, A> {
+    type Item = (K, V);
+    type Iter = IntoParIter<K, V, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.table.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Sync, S, A: Allocator> IntoParallelIterator for &'a HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a V);
+    type Iter = ParIter<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Send, S, A: Allocator> IntoParallelIterator for &'a mut HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a mut V);
+    type Iter = ParIterMut<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIterMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+/// Collect (key, value) pairs from a parallel iterator into a
+/// hashmap. If multiple pairs correspond to the same key, then the
+/// ones produced earlier in the parallel iterator will be
+/// overwritten, just as with a sequential iterator.
+impl<K, V, S> FromParallelIterator<(K, V)> for HashMap<K, V, S, Global>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher + Default,
+{
+    fn from_par_iter<P>(par_iter: P) -> Self
+    where
+        P: IntoParallelIterator<Item = (K, V)>,
+    {
+        let mut map = HashMap::default();
+        map.par_extend(par_iter);
+        map
+    }
+}
+
+/// Extend a hash map with items from a parallel iterator.
+impl<K, V, S, A> ParallelExtend<(K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+/// Extend a hash map with copied items from a parallel iterator.
+impl<'a, K, V, S, A> ParallelExtend<(&'a K, &'a V)> for HashMap<K, V, S, A>
+where
+    K: Copy + Eq + Hash + Sync,
+    V: Copy + Sync,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (&'a K, &'a V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+// This is equal to the normal `HashMap` -- no custom advantage.
+fn extend<K, V, S, A, I>(map: &mut HashMap<K, V, S, A>, par_iter: I)
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    I: IntoParallelIterator,
+    A: Allocator,
+    HashMap<K, V, S, A>: Extend<I::Item>,
+{
+    let (list, len) = super::helpers::collect(par_iter);
+
+    // Keys may be already present or show multiple times in the iterator.
+    // Reserve the entire length if the map is empty.
+    // Otherwise reserve half the length (rounded up), so the map
+    // will only resize twice in the worst case.
+    let reserve = if map.is_empty() { len } else { (len + 1) / 2 };
+    map.reserve(reserve);
+    for vec in list {
+        map.extend(vec);
+    }
+}
+
+#[cfg(test)]
+mod test_par_map {
+    use alloc::vec::Vec;
+    use core::hash::{Hash, Hasher};
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::hash_map::HashMap;
+
+    struct Dropable<'a> {
+        k: usize,
+        counter: &'a AtomicUsize,
+    }
+
+    impl Dropable<'_> {
+        fn new(k: usize, counter: &AtomicUsize) -> Dropable<'_> {
+            counter.fetch_add(1, Ordering::Relaxed);
+
+            Dropable { k, counter }
+        }
+    }
+
+    impl Drop for Dropable<'_> {
+        fn drop(&mut self) {
+            self.counter.fetch_sub(1, Ordering::Relaxed);
+        }
+    }
+
+    impl Clone for Dropable<'_> {
+        fn clone(&self) -> Self {
+            Dropable::new(self.k, self.counter)
+        }
+    }
+
+    impl Hash for Dropable<'_> {
+        fn hash<H>(&self, state: &mut H)
+        where
+            H: Hasher,
+        {
+            self.k.hash(state);
+        }
+    }
+
+    impl PartialEq for Dropable<'_> {
+        fn eq(&self, other: &Self) -> bool {
+            self.k == other.k
+        }
+    }
+
+    impl Eq for Dropable<'_> {}
+
+    #[test]
+    fn test_into_iter_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Dropable::new(i, &key);
+                let d2 = Dropable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the iterator does not leak anything.
+        drop(hm.clone().into_par_iter());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.into_par_iter().filter(|(key, _)| key.k < 50).collect();
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_drain_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let mut hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Dropable::new(i, &key);
+                let d2 = Dropable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the drain iterator does not leak anything.
+        drop(hm.clone().par_drain());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.drain().filter(|(key, _)| key.k < 50).collect();
+            assert!(hm.is_empty());
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_empty_iter() {
+        let mut m: HashMap<isize, bool> = HashMap::new();
+        assert_eq!(m.par_drain().count(), 0);
+        assert_eq!(m.par_keys().count(), 0);
+        assert_eq!(m.par_values().count(), 0);
+        assert_eq!(m.par_values_mut().count(), 0);
+        assert_eq!(m.par_iter().count(), 0);
+        assert_eq!(m.par_iter_mut().count(), 0);
+        assert_eq!(m.len(), 0);
+        assert!(m.is_empty());
+        assert_eq!(m.into_par_iter().count(), 0);
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut m = HashMap::with_capacity(4);
+        for i in 0..32 {
+            assert!(m.insert(i, i * 2).is_none());
+        }
+        assert_eq!(m.len(), 32);
+
+        let observed = AtomicUsize::new(0);
+
+        m.par_iter().for_each(|(k, v)| {
+            assert_eq!(*v, *k * 2);
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_keys() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let keys: Vec<_> = map.par_keys().cloned().collect();
+        assert_eq!(keys.len(), 3);
+        assert!(keys.contains(&1));
+        assert!(keys.contains(&2));
+        assert!(keys.contains(&3));
+    }
+
+    #[test]
+    fn test_values() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&'a'));
+        assert!(values.contains(&'b'));
+        assert!(values.contains(&'c'));
+    }
+
+    #[test]
+    fn test_values_mut() {
+        let vec = vec![(1, 1), (2, 2), (3, 3)];
+        let mut map: HashMap<_, _> = vec.into_par_iter().collect();
+        map.par_values_mut().for_each(|value| *value *= 2);
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&2));
+        assert!(values.contains(&4));
+        assert!(values.contains(&6));
+    }
+
+    #[test]
+    fn test_eq() {
+        let mut m1 = HashMap::new();
+        m1.insert(1, 2);
+        m1.insert(2, 3);
+        m1.insert(3, 4);
+
+        let mut m2 = HashMap::new();
+        m2.insert(1, 2);
+        m2.insert(2, 3);
+
+        assert!(!m1.par_eq(&m2));
+
+        m2.insert(3, 4);
+
+        assert!(m1.par_eq(&m2));
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.par_iter().cloned().collect();
+
+        for &(k, v) in &xs {
+            assert_eq!(map.get(&k), Some(&v));
+        }
+    }
+
+    #[test]
+    fn test_extend_ref() {
+        let mut a = HashMap::new();
+        a.insert(1, "one");
+        let mut b = HashMap::new();
+        b.insert(2, "two");
+        b.insert(3, "three");
+
+        a.par_extend(&b);
+
+        assert_eq!(a.len(), 3);
+        assert_eq!(a[&1], "one");
+        assert_eq!(a[&2], "two");
+        assert_eq!(a[&3], "three");
+    }
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rayon/mod.rs b/vendor/hashbrown/src/external_trait_impls/rayon/mod.rs
new file mode 100644
index 0000000..99337a1
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/mod.rs
@@ -0,0 +1,4 @@
+mod helpers;
+pub(crate) mod map;
+pub(crate) mod raw;
+pub(crate) mod set;
diff --git a/vendor/hashbrown/src/external_trait_impls/rayon/raw.rs b/vendor/hashbrown/src/external_trait_impls/rayon/raw.rs
new file mode 100644
index 0000000..612be47
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/raw.rs
@@ -0,0 +1,230 @@
+use crate::raw::Bucket;
+use crate::raw::{Allocator, Global, RawIter, RawIterRange, RawTable};
+use crate::scopeguard::guard;
+use core::marker::PhantomData;
+use core::mem;
+use core::ptr::NonNull;
+use rayon::iter::{
+    plumbing::{self, Folder, UnindexedConsumer, UnindexedProducer},
+    ParallelIterator,
+};
+
+/// Parallel iterator which returns a raw pointer to every full bucket in the table.
+pub struct RawParIter<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn iter(&self) -> RawIterRange<T> {
+        self.iter.clone()
+    }
+}
+
+impl<T> Clone for RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            iter: self.iter.clone(),
+        }
+    }
+}
+
+impl<T> From<RawIter<T>> for RawParIter<T> {
+    fn from(it: RawIter<T>) -> Self {
+        RawParIter { iter: it.iter }
+    }
+}
+
+impl<T> ParallelIterator for RawParIter<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = ParIterProducer { iter: self.iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Producer which returns a `Bucket<T>` for every element.
+struct ParIterProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> UnindexedProducer for ParIterProducer<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.split();
+        let left = ParIterProducer { iter: left };
+        let right = right.map(|right| ParIterProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.iter)
+    }
+}
+
+/// Parallel iterator which consumes a table and returns elements.
+pub struct RawIntoParIter<T, A: Allocator = Global> {
+    table: RawTable<T, A>,
+}
+
+impl<T, A: Allocator> RawIntoParIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for RawIntoParIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let iter = unsafe { self.table.iter().iter };
+        let _guard = guard(self.table.into_allocation(), |alloc| {
+            if let Some((ptr, layout, ref alloc)) = *alloc {
+                unsafe {
+                    alloc.deallocate(ptr, layout);
+                }
+            }
+        });
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Parallel iterator which consumes elements without freeing the table storage.
+pub struct RawParDrain<'a, T, A: Allocator = Global> {
+    // We don't use a &'a mut RawTable<T> because we want RawParDrain to be
+    // covariant over T.
+    table: NonNull<RawTable<T, A>>,
+    marker: PhantomData<&'a RawTable<T, A>>,
+}
+
+unsafe impl<T: Send, A: Allocator> Send for RawParDrain<'_, T, A> {}
+
+impl<T, A: Allocator> RawParDrain<'_, T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.as_ref().par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator> ParallelIterator for RawParDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let _guard = guard(self.table, |table| unsafe {
+            table.as_mut().clear_no_drop();
+        });
+        let iter = unsafe { self.table.as_ref().iter().iter };
+        mem::forget(self);
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<T, A: Allocator> Drop for RawParDrain<'_, T, A> {
+    fn drop(&mut self) {
+        // If drive_unindexed is not called then simply clear the table.
+        unsafe {
+            self.table.as_mut().clear();
+        }
+    }
+}
+
+/// Producer which will consume all elements in the range, even if it is dropped
+/// halfway through.
+struct ParDrainProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T: Send> UnindexedProducer for ParDrainProducer<T> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.clone().split();
+        mem::forget(self);
+        let left = ParDrainProducer { iter: left };
+        let right = right.map(|right| ParDrainProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(mut self, mut folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        // Make sure to modify the iterator in-place so that any remaining
+        // elements are processed in our Drop impl.
+        for item in &mut self.iter {
+            folder = folder.consume(unsafe { item.read() });
+            if folder.full() {
+                return folder;
+            }
+        }
+
+        // If we processed all elements then we don't need to run the drop.
+        mem::forget(self);
+        folder
+    }
+}
+
+impl<T> Drop for ParDrainProducer<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        // Drop all remaining elements
+        if mem::needs_drop::<T>() {
+            for item in &mut self.iter {
+                unsafe {
+                    item.drop();
+                }
+            }
+        }
+    }
+}
+
+impl<T, A: Allocator> RawTable<T, A> {
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub unsafe fn par_iter(&self) -> RawParIter<T> {
+        RawParIter {
+            iter: self.iter().iter,
+        }
+    }
+
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_par_iter(self) -> RawIntoParIter<T, A> {
+        RawIntoParIter { table: self }
+    }
+
+    /// Returns a parallel iterator which consumes all elements of a `RawTable`
+    /// without freeing its memory allocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> RawParDrain<'_, T, A> {
+        RawParDrain {
+            table: NonNull::from(self),
+            marker: PhantomData,
+        }
+    }
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rayon/set.rs b/vendor/hashbrown/src/external_trait_impls/rayon/set.rs
new file mode 100644
index 0000000..3de98fc
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/set.rs
@@ -0,0 +1,659 @@
+//! Rayon extensions for `HashSet`.
+
+use super::map;
+use crate::hash_set::HashSet;
+use crate::raw::{Allocator, Global};
+use core::hash::{BuildHasher, Hash};
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+
+/// Parallel iterator over elements of a consumed set.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashSet`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashSet.html#method.into_par_iter
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<T, A: Allocator = Global> {
+    inner: map::IntoParIter<T, (), A>,
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
+    type Item = T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(|(k, _)| k).drive_unindexed(consumer)
+    }
+}
+
+/// Parallel draining iterator over entries of a set.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashSet.html#method.par_drain
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParDrain<'a, T, A: Allocator = Global> {
+    inner: map::ParDrain<'a, T, (), A>,
+}
+
+impl<T: Send, A: Allocator + Send + Sync> ParallelIterator for ParDrain<'_, T, A> {
+    type Item = T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(|(k, _)| k).drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in a set.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashSet`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashSet.html#method.par_iter
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, T> {
+    inner: map::ParKeys<'a, T, ()>,
+}
+
+impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the difference of
+/// sets.
+///
+/// This iterator is created by the [`par_difference`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_difference`]: /hashbrown/struct.HashSet.html#method.par_difference
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParDifference<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParDifference<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .into_par_iter()
+            .filter(|&x| !self.b.contains(x))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the symmetric
+/// difference of sets.
+///
+/// This iterator is created by the [`par_symmetric_difference`] method on
+/// [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_symmetric_difference`]: /hashbrown/struct.HashSet.html#method.par_symmetric_difference
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParSymmetricDifference<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParSymmetricDifference<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .par_difference(self.b)
+            .chain(self.b.par_difference(self.a))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the intersection of
+/// sets.
+///
+/// This iterator is created by the [`par_intersection`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_intersection`]: /hashbrown/struct.HashSet.html#method.par_intersection
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParIntersection<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParIntersection<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.a
+            .into_par_iter()
+            .filter(|&x| self.b.contains(x))
+            .drive_unindexed(consumer)
+    }
+}
+
+/// Parallel iterator over shared references to elements in the union of sets.
+///
+/// This iterator is created by the [`par_union`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`par_union`]: /hashbrown/struct.HashSet.html#method.par_union
+/// [`HashSet`]: /hashbrown/struct.HashSet.html
+pub struct ParUnion<'a, T, S, A: Allocator = Global> {
+    a: &'a HashSet<T, S, A>,
+    b: &'a HashSet<T, S, A>,
+}
+
+impl<'a, T, S, A> ParallelIterator for ParUnion<'a, T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    type Item = &'a T;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        // We'll iterate one set in full, and only the remaining difference from the other.
+        // Use the smaller set for the difference in order to reduce hash lookups.
+        let (smaller, larger) = if self.a.len() <= self.b.len() {
+            (self.a, self.b)
+        } else {
+            (self.b, self.a)
+        };
+        larger
+            .into_par_iter()
+            .chain(smaller.par_difference(larger))
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    T: Eq + Hash + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    /// Visits (potentially in parallel) the values representing the union,
+    /// i.e. all the values in `self` or `other`, without duplicates.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_union<'a>(&'a self, other: &'a Self) -> ParUnion<'a, T, S, A> {
+        ParUnion { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the difference,
+    /// i.e. the values that are in `self` but not in `other`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_difference<'a>(&'a self, other: &'a Self) -> ParDifference<'a, T, S, A> {
+        ParDifference { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the symmetric
+    /// difference, i.e. the values that are in `self` or in `other` but not in both.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_symmetric_difference<'a>(
+        &'a self,
+        other: &'a Self,
+    ) -> ParSymmetricDifference<'a, T, S, A> {
+        ParSymmetricDifference { a: self, b: other }
+    }
+
+    /// Visits (potentially in parallel) the values representing the
+    /// intersection, i.e. the values that are both in `self` and `other`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_intersection<'a>(&'a self, other: &'a Self) -> ParIntersection<'a, T, S, A> {
+        ParIntersection { a: self, b: other }
+    }
+
+    /// Returns `true` if `self` has no elements in common with `other`.
+    /// This is equivalent to checking for an empty intersection.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_disjoint(&self, other: &Self) -> bool {
+        self.into_par_iter().all(|x| !other.contains(x))
+    }
+
+    /// Returns `true` if the set is a subset of another,
+    /// i.e. `other` contains at least all the values in `self`.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_subset(&self, other: &Self) -> bool {
+        if self.len() <= other.len() {
+            self.into_par_iter().all(|x| other.contains(x))
+        } else {
+            false
+        }
+    }
+
+    /// Returns `true` if the set is a superset of another,
+    /// i.e. `self` contains at least all the values in `other`.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_is_superset(&self, other: &Self) -> bool {
+        other.par_is_subset(self)
+    }
+
+    /// Returns `true` if the set is equal to another,
+    /// i.e. both sets contain the same values.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_eq(&self, other: &Self) -> bool {
+        self.len() == other.len() && self.par_is_subset(other)
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    T: Eq + Hash + Send,
+    A: Allocator + Send,
+{
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the set's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, T, A> {
+        ParDrain {
+            inner: self.map.par_drain(),
+        }
+    }
+}
+
+impl<T: Send, S, A: Allocator + Send> IntoParallelIterator for HashSet<T, S, A> {
+    type Item = T;
+    type Iter = IntoParIter<T, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.map.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, T: Sync, S, A: Allocator> IntoParallelIterator for &'a HashSet<T, S, A> {
+    type Item = &'a T;
+    type Iter = ParIter<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: self.map.par_keys(),
+        }
+    }
+}
+
+/// Collect values from a parallel iterator into a hashset.
+impl<T, S> FromParallelIterator<T> for HashSet<T, S, Global>
+where
+    T: Eq + Hash + Send,
+    S: BuildHasher + Default,
+{
+    fn from_par_iter<P>(par_iter: P) -> Self
+    where
+        P: IntoParallelIterator<Item = T>,
+    {
+        let mut set = HashSet::default();
+        set.par_extend(par_iter);
+        set
+    }
+}
+
+/// Extend a hash set with items from a parallel iterator.
+impl<T, S> ParallelExtend<T> for HashSet<T, S, Global>
+where
+    T: Eq + Hash + Send,
+    S: BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = T>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+/// Extend a hash set with copied items from a parallel iterator.
+impl<'a, T, S> ParallelExtend<&'a T> for HashSet<T, S, Global>
+where
+    T: 'a + Copy + Eq + Hash + Sync,
+    S: BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = &'a T>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+// This is equal to the normal `HashSet` -- no custom advantage.
+fn extend<T, S, I, A>(set: &mut HashSet<T, S, A>, par_iter: I)
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+    I: IntoParallelIterator,
+    HashSet<T, S, A>: Extend<I::Item>,
+{
+    let (list, len) = super::helpers::collect(par_iter);
+
+    // Values may be already present or show multiple times in the iterator.
+    // Reserve the entire length if the set is empty.
+    // Otherwise reserve half the length (rounded up), so the set
+    // will only resize twice in the worst case.
+    let reserve = if set.is_empty() { len } else { (len + 1) / 2 };
+    set.reserve(reserve);
+    for vec in list {
+        set.extend(vec);
+    }
+}
+
+#[cfg(test)]
+mod test_par_set {
+    use alloc::vec::Vec;
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::hash_set::HashSet;
+
+    #[test]
+    fn test_disjoint() {
+        let mut xs = HashSet::new();
+        let mut ys = HashSet::new();
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(xs.insert(5));
+        assert!(ys.insert(11));
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(xs.insert(7));
+        assert!(xs.insert(19));
+        assert!(xs.insert(4));
+        assert!(ys.insert(2));
+        assert!(ys.insert(-11));
+        assert!(xs.par_is_disjoint(&ys));
+        assert!(ys.par_is_disjoint(&xs));
+        assert!(ys.insert(7));
+        assert!(!xs.par_is_disjoint(&ys));
+        assert!(!ys.par_is_disjoint(&xs));
+    }
+
+    #[test]
+    fn test_subset_and_superset() {
+        let mut a = HashSet::new();
+        assert!(a.insert(0));
+        assert!(a.insert(5));
+        assert!(a.insert(11));
+        assert!(a.insert(7));
+
+        let mut b = HashSet::new();
+        assert!(b.insert(0));
+        assert!(b.insert(7));
+        assert!(b.insert(19));
+        assert!(b.insert(250));
+        assert!(b.insert(11));
+        assert!(b.insert(200));
+
+        assert!(!a.par_is_subset(&b));
+        assert!(!a.par_is_superset(&b));
+        assert!(!b.par_is_subset(&a));
+        assert!(!b.par_is_superset(&a));
+
+        assert!(b.insert(5));
+
+        assert!(a.par_is_subset(&b));
+        assert!(!a.par_is_superset(&b));
+        assert!(!b.par_is_subset(&a));
+        assert!(b.par_is_superset(&a));
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut a = HashSet::new();
+        for i in 0..32 {
+            assert!(a.insert(i));
+        }
+        let observed = AtomicUsize::new(0);
+        a.par_iter().for_each(|k| {
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_intersection() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(11));
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(77));
+        assert!(a.insert(103));
+        assert!(a.insert(5));
+        assert!(a.insert(-5));
+
+        assert!(b.insert(2));
+        assert!(b.insert(11));
+        assert!(b.insert(77));
+        assert!(b.insert(-9));
+        assert!(b.insert(-42));
+        assert!(b.insert(5));
+        assert!(b.insert(3));
+
+        let expected = [3, 5, 11, 77];
+        let i = a
+            .par_intersection(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+
+        let expected = [1, 5, 11];
+        let i = a
+            .par_difference(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_symmetric_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+        assert!(b.insert(14));
+        assert!(b.insert(22));
+
+        let expected = [-2, 1, 5, 11, 14, 22];
+        let i = a
+            .par_symmetric_difference(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_union() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+        assert!(a.insert(16));
+        assert!(a.insert(19));
+        assert!(a.insert(24));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(1));
+        assert!(b.insert(5));
+        assert!(b.insert(9));
+        assert!(b.insert(13));
+        assert!(b.insert(19));
+
+        let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
+        let i = a
+            .par_union(&b)
+            .map(|x| {
+                assert!(expected.contains(x));
+                1
+            })
+            .sum::<usize>();
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+        let set: HashSet<_> = xs.par_iter().cloned().collect();
+
+        for x in &xs {
+            assert!(set.contains(x));
+        }
+    }
+
+    #[test]
+    fn test_move_iter() {
+        let hs = {
+            let mut hs = HashSet::new();
+
+            hs.insert('a');
+            hs.insert('b');
+
+            hs
+        };
+
+        let v = hs.into_par_iter().collect::<Vec<char>>();
+        assert!(v == ['a', 'b'] || v == ['b', 'a']);
+    }
+
+    #[test]
+    fn test_eq() {
+        // These constants once happened to expose a bug in insert().
+        // I'm keeping them around to prevent a regression.
+        let mut s1 = HashSet::new();
+
+        s1.insert(1);
+        s1.insert(2);
+        s1.insert(3);
+
+        let mut s2 = HashSet::new();
+
+        s2.insert(1);
+        s2.insert(2);
+
+        assert!(!s1.par_eq(&s2));
+
+        s2.insert(3);
+
+        assert!(s1.par_eq(&s2));
+    }
+
+    #[test]
+    fn test_extend_ref() {
+        let mut a = HashSet::new();
+        a.insert(1);
+
+        a.par_extend(&[2, 3, 4][..]);
+
+        assert_eq!(a.len(), 4);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+
+        let mut b = HashSet::new();
+        b.insert(5);
+        b.insert(6);
+
+        a.par_extend(&b);
+
+        assert_eq!(a.len(), 6);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+        assert!(a.contains(&5));
+        assert!(a.contains(&6));
+    }
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rkyv/hash_map.rs b/vendor/hashbrown/src/external_trait_impls/rkyv/hash_map.rs
new file mode 100644
index 0000000..fae7f76
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rkyv/hash_map.rs
@@ -0,0 +1,125 @@
+use crate::HashMap;
+use core::{
+    borrow::Borrow,
+    hash::{BuildHasher, Hash},
+};
+use rkyv::{
+    collections::hash_map::{ArchivedHashMap, HashMapResolver},
+    ser::{ScratchSpace, Serializer},
+    Archive, Deserialize, Fallible, Serialize,
+};
+
+impl<K: Archive + Hash + Eq, V: Archive, S> Archive for HashMap<K, V, S>
+where
+    K::Archived: Hash + Eq,
+{
+    type Archived = ArchivedHashMap<K::Archived, V::Archived>;
+    type Resolver = HashMapResolver;
+
+    #[inline]
+    unsafe fn resolve(&self, pos: usize, resolver: Self::Resolver, out: *mut Self::Archived) {
+        ArchivedHashMap::resolve_from_len(self.len(), pos, resolver, out);
+    }
+}
+
+impl<K, V, S, RandomState> Serialize<S> for HashMap<K, V, RandomState>
+where
+    K: Serialize<S> + Hash + Eq,
+    K::Archived: Hash + Eq,
+    V: Serialize<S>,
+    S: Serializer + ScratchSpace + ?Sized,
+{
+    #[inline]
+    fn serialize(&self, serializer: &mut S) -> Result<Self::Resolver, S::Error> {
+        unsafe { ArchivedHashMap::serialize_from_iter(self.iter(), serializer) }
+    }
+}
+
+impl<K: Archive + Hash + Eq, V: Archive, D: Fallible + ?Sized, S: Default + BuildHasher>
+    Deserialize<HashMap<K, V, S>, D> for ArchivedHashMap<K::Archived, V::Archived>
+where
+    K::Archived: Deserialize<K, D> + Hash + Eq,
+    V::Archived: Deserialize<V, D>,
+{
+    #[inline]
+    fn deserialize(&self, deserializer: &mut D) -> Result<HashMap<K, V, S>, D::Error> {
+        let mut result = HashMap::with_capacity_and_hasher(self.len(), S::default());
+        for (k, v) in self.iter() {
+            result.insert(k.deserialize(deserializer)?, v.deserialize(deserializer)?);
+        }
+        Ok(result)
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, V, AK: Hash + Eq, AV: PartialEq<V>, S: BuildHasher>
+    PartialEq<HashMap<K, V, S>> for ArchivedHashMap<AK, AV>
+{
+    #[inline]
+    fn eq(&self, other: &HashMap<K, V, S>) -> bool {
+        if self.len() != other.len() {
+            false
+        } else {
+            self.iter()
+                .all(|(key, value)| other.get(key).map_or(false, |v| value.eq(v)))
+        }
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, V, AK: Hash + Eq, AV: PartialEq<V>>
+    PartialEq<ArchivedHashMap<AK, AV>> for HashMap<K, V>
+{
+    #[inline]
+    fn eq(&self, other: &ArchivedHashMap<AK, AV>) -> bool {
+        other.eq(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::HashMap;
+    use alloc::string::String;
+    use rkyv::{
+        archived_root, check_archived_root,
+        ser::{serializers::AllocSerializer, Serializer},
+        Deserialize, Infallible,
+    };
+
+    #[test]
+    fn index_map() {
+        let mut value = HashMap::new();
+        value.insert(String::from("foo"), 10);
+        value.insert(String::from("bar"), 20);
+        value.insert(String::from("baz"), 40);
+        value.insert(String::from("bat"), 80);
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        let archived = unsafe { archived_root::<HashMap<String, i32>>(result.as_ref()) };
+
+        assert_eq!(value.len(), archived.len());
+        for (k, v) in value.iter() {
+            let (ak, av) = archived.get_key_value(k.as_str()).unwrap();
+            assert_eq!(k, ak);
+            assert_eq!(v, av);
+        }
+
+        let deserialized: HashMap<String, i32> = archived.deserialize(&mut Infallible).unwrap();
+        assert_eq!(value, deserialized);
+    }
+
+    #[test]
+    fn validate_index_map() {
+        let mut value = HashMap::new();
+        value.insert(String::from("foo"), 10);
+        value.insert(String::from("bar"), 20);
+        value.insert(String::from("baz"), 40);
+        value.insert(String::from("bat"), 80);
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        check_archived_root::<HashMap<String, i32>>(result.as_ref())
+            .expect("failed to validate archived index map");
+    }
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rkyv/hash_set.rs b/vendor/hashbrown/src/external_trait_impls/rkyv/hash_set.rs
new file mode 100644
index 0000000..c8a69cf
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rkyv/hash_set.rs
@@ -0,0 +1,123 @@
+use crate::HashSet;
+use core::{
+    borrow::Borrow,
+    hash::{BuildHasher, Hash},
+};
+use rkyv::{
+    collections::hash_set::{ArchivedHashSet, HashSetResolver},
+    ser::{ScratchSpace, Serializer},
+    Archive, Deserialize, Fallible, Serialize,
+};
+
+impl<K: Archive + Hash + Eq, S> Archive for HashSet<K, S>
+where
+    K::Archived: Hash + Eq,
+{
+    type Archived = ArchivedHashSet<K::Archived>;
+    type Resolver = HashSetResolver;
+
+    #[inline]
+    unsafe fn resolve(&self, pos: usize, resolver: Self::Resolver, out: *mut Self::Archived) {
+        ArchivedHashSet::<K::Archived>::resolve_from_len(self.len(), pos, resolver, out);
+    }
+}
+
+impl<K, S, RS> Serialize<S> for HashSet<K, RS>
+where
+    K::Archived: Hash + Eq,
+    K: Serialize<S> + Hash + Eq,
+    S: ScratchSpace + Serializer + ?Sized,
+{
+    #[inline]
+    fn serialize(&self, serializer: &mut S) -> Result<Self::Resolver, S::Error> {
+        unsafe { ArchivedHashSet::serialize_from_iter(self.iter(), serializer) }
+    }
+}
+
+impl<K, D, S> Deserialize<HashSet<K, S>, D> for ArchivedHashSet<K::Archived>
+where
+    K: Archive + Hash + Eq,
+    K::Archived: Deserialize<K, D> + Hash + Eq,
+    D: Fallible + ?Sized,
+    S: Default + BuildHasher,
+{
+    #[inline]
+    fn deserialize(&self, deserializer: &mut D) -> Result<HashSet<K, S>, D::Error> {
+        let mut result = HashSet::with_hasher(S::default());
+        for k in self.iter() {
+            result.insert(k.deserialize(deserializer)?);
+        }
+        Ok(result)
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, AK: Hash + Eq, S: BuildHasher> PartialEq<HashSet<K, S>>
+    for ArchivedHashSet<AK>
+{
+    #[inline]
+    fn eq(&self, other: &HashSet<K, S>) -> bool {
+        if self.len() != other.len() {
+            false
+        } else {
+            self.iter().all(|key| other.get(key).is_some())
+        }
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, AK: Hash + Eq, S: BuildHasher> PartialEq<ArchivedHashSet<AK>>
+    for HashSet<K, S>
+{
+    #[inline]
+    fn eq(&self, other: &ArchivedHashSet<AK>) -> bool {
+        other.eq(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::HashSet;
+    use alloc::string::String;
+    use rkyv::{
+        archived_root, check_archived_root,
+        ser::{serializers::AllocSerializer, Serializer},
+        Deserialize, Infallible,
+    };
+
+    #[test]
+    fn index_set() {
+        let mut value = HashSet::new();
+        value.insert(String::from("foo"));
+        value.insert(String::from("bar"));
+        value.insert(String::from("baz"));
+        value.insert(String::from("bat"));
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        let archived = unsafe { archived_root::<HashSet<String>>(result.as_ref()) };
+
+        assert_eq!(value.len(), archived.len());
+        for k in value.iter() {
+            let ak = archived.get(k.as_str()).unwrap();
+            assert_eq!(k, ak);
+        }
+
+        let deserialized: HashSet<String> = archived.deserialize(&mut Infallible).unwrap();
+        assert_eq!(value, deserialized);
+    }
+
+    #[test]
+    fn validate_index_set() {
+        let mut value = HashSet::new();
+        value.insert(String::from("foo"));
+        value.insert(String::from("bar"));
+        value.insert(String::from("baz"));
+        value.insert(String::from("bat"));
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        check_archived_root::<HashSet<String>>(result.as_ref())
+            .expect("failed to validate archived index set");
+    }
+}
diff --git a/vendor/hashbrown/src/external_trait_impls/rkyv/mod.rs b/vendor/hashbrown/src/external_trait_impls/rkyv/mod.rs
new file mode 100644
index 0000000..2bde6a0
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/rkyv/mod.rs
@@ -0,0 +1,2 @@
+mod hash_map;
+mod hash_set;
diff --git a/vendor/hashbrown/src/external_trait_impls/serde.rs b/vendor/hashbrown/src/external_trait_impls/serde.rs
new file mode 100644
index 0000000..0a76dbe
--- /dev/null
+++ b/vendor/hashbrown/src/external_trait_impls/serde.rs
@@ -0,0 +1,220 @@
+mod size_hint {
+    use core::cmp;
+
+    /// This presumably exists to prevent denial of service attacks.
+    ///
+    /// Original discussion: https://github.com/serde-rs/serde/issues/1114.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn cautious(hint: Option<usize>) -> usize {
+        cmp::min(hint.unwrap_or(0), 4096)
+    }
+}
+
+mod map {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde::de::{Deserialize, Deserializer, MapAccess, Visitor};
+    use serde::ser::{Serialize, Serializer};
+
+    use crate::hash_map::HashMap;
+
+    use super::size_hint;
+
+    impl<K, V, H, A> Serialize for HashMap<K, V, H, A>
+    where
+        K: Serialize + Eq + Hash,
+        V: Serialize,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_map(self)
+        }
+    }
+
+    impl<'de, K, V, S, A> Deserialize<'de> for HashMap<K, V, S, A>
+    where
+        K: Deserialize<'de> + Eq + Hash,
+        V: Deserialize<'de>,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct MapVisitor<K, V, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashMap<K, V, S, A>>,
+            }
+
+            impl<'de, K, V, S, A> Visitor<'de> for MapVisitor<K, V, S, A>
+            where
+                K: Deserialize<'de> + Eq + Hash,
+                V: Deserialize<'de>,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashMap<K, V, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a map")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
+                where
+                    M: MapAccess<'de>,
+                {
+                    let mut values = HashMap::with_capacity_and_hasher_in(
+                        size_hint::cautious(map.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some((key, value)) = map.next_entry()? {
+                        values.insert(key, value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = MapVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_map(visitor)
+        }
+    }
+}
+
+mod set {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde::de::{Deserialize, Deserializer, SeqAccess, Visitor};
+    use serde::ser::{Serialize, Serializer};
+
+    use crate::hash_set::HashSet;
+
+    use super::size_hint;
+
+    impl<T, H, A> Serialize for HashSet<T, H, A>
+    where
+        T: Serialize + Eq + Hash,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_seq(self)
+        }
+    }
+
+    impl<'de, T, S, A> Deserialize<'de> for HashSet<T, S, A>
+    where
+        T: Deserialize<'de> + Eq + Hash,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqVisitor<T, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashSet<T, S, A>>,
+            }
+
+            impl<'de, T, S, A> Visitor<'de> for SeqVisitor<T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashSet<T, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    let mut values = HashSet::with_capacity_and_hasher_in(
+                        size_hint::cautious(seq.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some(value) = seq.next_element()? {
+                        values.insert(value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = SeqVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_seq(visitor)
+        }
+
+        #[allow(clippy::missing_errors_doc)]
+        fn deserialize_in_place<D>(deserializer: D, place: &mut Self) -> Result<(), D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqInPlaceVisitor<'a, T, S, A>(&'a mut HashSet<T, S, A>)
+            where
+                A: Allocator;
+
+            impl<'a, 'de, T, S, A> Visitor<'de> for SeqInPlaceVisitor<'a, T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator,
+            {
+                type Value = ();
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    self.0.clear();
+                    self.0.reserve(size_hint::cautious(seq.size_hint()));
+
+                    while let Some(value) = seq.next_element()? {
+                        self.0.insert(value);
+                    }
+
+                    Ok(())
+                }
+            }
+
+            deserializer.deserialize_seq(SeqInPlaceVisitor(place))
+        }
+    }
+}
diff --git a/vendor/hashbrown/src/lib.rs b/vendor/hashbrown/src/lib.rs
new file mode 100644
index 0000000..06b1068
--- /dev/null
+++ b/vendor/hashbrown/src/lib.rs
@@ -0,0 +1,171 @@
+//! This crate is a Rust port of Google's high-performance [SwissTable] hash
+//! map, adapted to make it a drop-in replacement for Rust's standard `HashMap`
+//! and `HashSet` types.
+//!
+//! The original C++ version of [SwissTable] can be found [here], and this
+//! [CppCon talk] gives an overview of how the algorithm works.
+//!
+//! [SwissTable]: https://abseil.io/blog/20180927-swisstables
+//! [here]: https://github.com/abseil/abseil-cpp/blob/master/absl/container/internal/raw_hash_set.h
+//! [CppCon talk]: https://www.youtube.com/watch?v=ncHmEUmJZf4
+
+#![no_std]
+#![cfg_attr(
+    feature = "nightly",
+    feature(
+        test,
+        core_intrinsics,
+        dropck_eyepatch,
+        min_specialization,
+        extend_one,
+        allocator_api,
+        slice_ptr_get,
+        maybe_uninit_array_assume_init,
+        strict_provenance
+    )
+)]
+#![allow(
+    clippy::doc_markdown,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::option_if_let_else,
+    clippy::redundant_else,
+    clippy::manual_map,
+    clippy::missing_safety_doc,
+    clippy::missing_errors_doc
+)]
+#![warn(missing_docs)]
+#![warn(rust_2018_idioms)]
+#![cfg_attr(feature = "nightly", warn(fuzzy_provenance_casts))]
+
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
+#[cfg_attr(test, macro_use)]
+extern crate alloc;
+
+#[cfg(feature = "nightly")]
+#[cfg(doctest)]
+doc_comment::doctest!("../README.md");
+
+#[macro_use]
+mod macros;
+
+#[cfg(feature = "raw")]
+/// Experimental and unsafe `RawTable` API. This module is only available if the
+/// `raw` feature is enabled.
+pub mod raw {
+    // The RawTable API is still experimental and is not properly documented yet.
+    #[allow(missing_docs)]
+    #[path = "mod.rs"]
+    mod inner;
+    pub use inner::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash maps.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::raw::*;
+    }
+}
+#[cfg(not(feature = "raw"))]
+mod raw;
+
+mod external_trait_impls;
+mod map;
+#[cfg(feature = "rustc-internal-api")]
+mod rustc_entry;
+mod scopeguard;
+mod set;
+
+pub mod hash_map {
+    //! A hash map implemented with quadratic probing and SIMD lookup.
+    pub use crate::map::*;
+
+    #[cfg(feature = "rustc-internal-api")]
+    pub use crate::rustc_entry::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash maps.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::map::*;
+    }
+}
+pub mod hash_set {
+    //! A hash set implemented as a `HashMap` where the value is `()`.
+    pub use crate::set::*;
+
+    #[cfg(feature = "rayon")]
+    /// [rayon]-based parallel iterator types for hash sets.
+    /// You will rarely need to interact with it directly unless you have need
+    /// to name one of the iterator types.
+    ///
+    /// [rayon]: https://docs.rs/rayon/1.0/rayon
+    pub mod rayon {
+        pub use crate::external_trait_impls::rayon::set::*;
+    }
+}
+
+pub use crate::map::HashMap;
+pub use crate::set::HashSet;
+
+#[cfg(feature = "equivalent")]
+pub use equivalent::Equivalent;
+
+// This is only used as a fallback when building as part of `std`.
+#[cfg(not(feature = "equivalent"))]
+/// Key equivalence trait.
+///
+/// This trait defines the function used to compare the input value with the
+/// map keys (or set values) during a lookup operation such as [`HashMap::get`]
+/// or [`HashSet::contains`].
+/// It is provided with a blanket implementation based on the
+/// [`Borrow`](core::borrow::Borrow) trait.
+///
+/// # Correctness
+///
+/// Equivalent values must hash to the same value.
+pub trait Equivalent<K: ?Sized> {
+    /// Checks if this value is equivalent to the given key.
+    ///
+    /// Returns `true` if both values are equivalent, and `false` otherwise.
+    ///
+    /// # Correctness
+    ///
+    /// When this function returns `true`, both `self` and `key` must hash to
+    /// the same value.
+    fn equivalent(&self, key: &K) -> bool;
+}
+
+#[cfg(not(feature = "equivalent"))]
+impl<Q: ?Sized, K: ?Sized> Equivalent<K> for Q
+where
+    Q: Eq,
+    K: core::borrow::Borrow<Q>,
+{
+    fn equivalent(&self, key: &K) -> bool {
+        self == key.borrow()
+    }
+}
+
+/// The error type for `try_reserve` methods.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum TryReserveError {
+    /// Error due to the computed capacity exceeding the collection's maximum
+    /// (usually `isize::MAX` bytes).
+    CapacityOverflow,
+
+    /// The memory allocator returned an error
+    AllocError {
+        /// The layout of the allocation request that failed.
+        layout: alloc::alloc::Layout,
+    },
+}
diff --git a/vendor/hashbrown/src/macros.rs b/vendor/hashbrown/src/macros.rs
new file mode 100644
index 0000000..eaba6be
--- /dev/null
+++ b/vendor/hashbrown/src/macros.rs
@@ -0,0 +1,70 @@
+// See the cfg-if crate.
+#[allow(unused_macro_rules)]
+macro_rules! cfg_if {
+    // match if/else chains with a final `else`
+    ($(
+        if #[cfg($($meta:meta),*)] { $($it:item)* }
+    ) else * else {
+        $($it2:item)*
+    }) => {
+        cfg_if! {
+            @__items
+            () ;
+            $( ( ($($meta),*) ($($it)*) ), )*
+            ( () ($($it2)*) ),
+        }
+    };
+
+    // match if/else chains lacking a final `else`
+    (
+        if #[cfg($($i_met:meta),*)] { $($i_it:item)* }
+        $(
+            else if #[cfg($($e_met:meta),*)] { $($e_it:item)* }
+        )*
+    ) => {
+        cfg_if! {
+            @__items
+            () ;
+            ( ($($i_met),*) ($($i_it)*) ),
+            $( ( ($($e_met),*) ($($e_it)*) ), )*
+            ( () () ),
+        }
+    };
+
+    // Internal and recursive macro to emit all the items
+    //
+    // Collects all the negated cfgs in a list at the beginning and after the
+    // semicolon is all the remaining items
+    (@__items ($($not:meta,)*) ; ) => {};
+    (@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), $($rest:tt)*) => {
+        // Emit all items within one block, applying an appropriate #[cfg]. The
+        // #[cfg] will require all `$m` matchers specified and must also negate
+        // all previous matchers.
+        cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* }
+
+        // Recurse to emit all other items in `$rest`, and when we do so add all
+        // our `$m` matchers to the list of `$not` matchers as future emissions
+        // will have to negate everything we just matched as well.
+        cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* }
+    };
+
+    // Internal macro to Apply a cfg attribute to a list of items
+    (@__apply $m:meta, $($it:item)*) => {
+        $(#[$m] $it)*
+    };
+}
+
+// Helper macro for specialization. This also helps avoid parse errors if the
+// default fn syntax for specialization changes in the future.
+#[cfg(feature = "nightly")]
+macro_rules! default_fn {
+	(#[$($a:tt)*] $($tt:tt)*) => {
+        #[$($a)*] default $($tt)*
+    }
+}
+#[cfg(not(feature = "nightly"))]
+macro_rules! default_fn {
+	($($tt:tt)*) => {
+        $($tt)*
+    }
+}
diff --git a/vendor/hashbrown/src/map.rs b/vendor/hashbrown/src/map.rs
new file mode 100644
index 0000000..edd1977
--- /dev/null
+++ b/vendor/hashbrown/src/map.rs
@@ -0,0 +1,8902 @@
+use crate::raw::{Allocator, Bucket, Global, RawDrain, RawIntoIter, RawIter, RawTable};
+use crate::{Equivalent, TryReserveError};
+use core::borrow::Borrow;
+use core::fmt::{self, Debug};
+use core::hash::{BuildHasher, Hash};
+use core::iter::{FromIterator, FusedIterator};
+use core::marker::PhantomData;
+use core::mem;
+use core::ops::Index;
+
+/// Default hasher for `HashMap`.
+#[cfg(feature = "ahash")]
+pub type DefaultHashBuilder = core::hash::BuildHasherDefault<ahash::AHasher>;
+
+/// Dummy default hasher for `HashMap`.
+#[cfg(not(feature = "ahash"))]
+pub enum DefaultHashBuilder {}
+
+/// A hash map implemented with quadratic probing and SIMD lookup.
+///
+/// The default hashing algorithm is currently [`AHash`], though this is
+/// subject to change at any point in the future. This hash function is very
+/// fast for all types of keys, but this algorithm will typically *not* protect
+/// against attacks such as HashDoS.
+///
+/// The hashing algorithm can be replaced on a per-`HashMap` basis using the
+/// [`default`], [`with_hasher`], and [`with_capacity_and_hasher`] methods. Many
+/// alternative algorithms are available on crates.io, such as the [`fnv`] crate.
+///
+/// It is required that the keys implement the [`Eq`] and [`Hash`] traits, although
+/// this can frequently be achieved by using `#[derive(PartialEq, Eq, Hash)]`.
+/// If you implement these yourself, it is important that the following
+/// property holds:
+///
+/// ```text
+/// k1 == k2 -> hash(k1) == hash(k2)
+/// ```
+///
+/// In other words, if two keys are equal, their hashes must be equal.
+///
+/// It is a logic error for a key to be modified in such a way that the key's
+/// hash, as determined by the [`Hash`] trait, or its equality, as determined by
+/// the [`Eq`] trait, changes while it is in the map. This is normally only
+/// possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
+///
+/// It is also a logic error for the [`Hash`] implementation of a key to panic.
+/// This is generally only possible if the trait is implemented manually. If a
+/// panic does occur then the contents of the `HashMap` may become corrupted and
+/// some items may be dropped from the table.
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// // Type inference lets us omit an explicit type signature (which
+/// // would be `HashMap<String, String>` in this example).
+/// let mut book_reviews = HashMap::new();
+///
+/// // Review some books.
+/// book_reviews.insert(
+///     "Adventures of Huckleberry Finn".to_string(),
+///     "My favorite book.".to_string(),
+/// );
+/// book_reviews.insert(
+///     "Grimms' Fairy Tales".to_string(),
+///     "Masterpiece.".to_string(),
+/// );
+/// book_reviews.insert(
+///     "Pride and Prejudice".to_string(),
+///     "Very enjoyable.".to_string(),
+/// );
+/// book_reviews.insert(
+///     "The Adventures of Sherlock Holmes".to_string(),
+///     "Eye lyked it alot.".to_string(),
+/// );
+///
+/// // Check for a specific one.
+/// // When collections store owned values (String), they can still be
+/// // queried using references (&str).
+/// if !book_reviews.contains_key("Les Misérables") {
+///     println!("We've got {} reviews, but Les Misérables ain't one.",
+///              book_reviews.len());
+/// }
+///
+/// // oops, this review has a lot of spelling mistakes, let's delete it.
+/// book_reviews.remove("The Adventures of Sherlock Holmes");
+///
+/// // Look up the values associated with some keys.
+/// let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
+/// for &book in &to_find {
+///     match book_reviews.get(book) {
+///         Some(review) => println!("{}: {}", book, review),
+///         None => println!("{} is unreviewed.", book)
+///     }
+/// }
+///
+/// // Look up the value for a key (will panic if the key is not found).
+/// println!("Review for Jane: {}", book_reviews["Pride and Prejudice"]);
+///
+/// // Iterate over everything.
+/// for (book, review) in &book_reviews {
+///     println!("{}: \"{}\"", book, review);
+/// }
+/// ```
+///
+/// `HashMap` also implements an [`Entry API`](#method.entry), which allows
+/// for more complex methods of getting, setting, updating and removing keys and
+/// their values:
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// // type inference lets us omit an explicit type signature (which
+/// // would be `HashMap<&str, u8>` in this example).
+/// let mut player_stats = HashMap::new();
+///
+/// fn random_stat_buff() -> u8 {
+///     // could actually return some random value here - let's just return
+///     // some fixed value for now
+///     42
+/// }
+///
+/// // insert a key only if it doesn't already exist
+/// player_stats.entry("health").or_insert(100);
+///
+/// // insert a key using a function that provides a new value only if it
+/// // doesn't already exist
+/// player_stats.entry("defence").or_insert_with(random_stat_buff);
+///
+/// // update a key, guarding against the key possibly not being set
+/// let stat = player_stats.entry("attack").or_insert(100);
+/// *stat += random_stat_buff();
+/// ```
+///
+/// The easiest way to use `HashMap` with a custom key type is to derive [`Eq`] and [`Hash`].
+/// We must also derive [`PartialEq`].
+///
+/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+/// [`PartialEq`]: https://doc.rust-lang.org/std/cmp/trait.PartialEq.html
+/// [`RefCell`]: https://doc.rust-lang.org/std/cell/struct.RefCell.html
+/// [`Cell`]: https://doc.rust-lang.org/std/cell/struct.Cell.html
+/// [`default`]: #method.default
+/// [`with_hasher`]: #method.with_hasher
+/// [`with_capacity_and_hasher`]: #method.with_capacity_and_hasher
+/// [`fnv`]: https://crates.io/crates/fnv
+/// [`AHash`]: https://crates.io/crates/ahash
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// #[derive(Hash, Eq, PartialEq, Debug)]
+/// struct Viking {
+///     name: String,
+///     country: String,
+/// }
+///
+/// impl Viking {
+///     /// Creates a new Viking.
+///     fn new(name: &str, country: &str) -> Viking {
+///         Viking { name: name.to_string(), country: country.to_string() }
+///     }
+/// }
+///
+/// // Use a HashMap to store the vikings' health points.
+/// let mut vikings = HashMap::new();
+///
+/// vikings.insert(Viking::new("Einar", "Norway"), 25);
+/// vikings.insert(Viking::new("Olaf", "Denmark"), 24);
+/// vikings.insert(Viking::new("Harald", "Iceland"), 12);
+///
+/// // Use derived implementation to print the status of the vikings.
+/// for (viking, health) in &vikings {
+///     println!("{:?} has {} hp", viking, health);
+/// }
+/// ```
+///
+/// A `HashMap` with fixed list of elements can be initialized from an array:
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let timber_resources: HashMap<&str, i32> = [("Norway", 100), ("Denmark", 50), ("Iceland", 10)]
+///     .iter().cloned().collect();
+/// // use the values stored in map
+/// ```
+pub struct HashMap<K, V, S = DefaultHashBuilder, A: Allocator = Global> {
+    pub(crate) hash_builder: S,
+    pub(crate) table: RawTable<(K, V), A>,
+}
+
+impl<K: Clone, V: Clone, S: Clone, A: Allocator + Clone> Clone for HashMap<K, V, S, A> {
+    fn clone(&self) -> Self {
+        HashMap {
+            hash_builder: self.hash_builder.clone(),
+            table: self.table.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        self.table.clone_from(&source.table);
+
+        // Update hash_builder only if we successfully cloned all elements.
+        self.hash_builder.clone_from(&source.hash_builder);
+    }
+}
+
+/// Ensures that a single closure type across uses of this which, in turn prevents multiple
+/// instances of any functions like RawTable::reserve from being generated
+#[cfg_attr(feature = "inline-more", inline)]
+pub(crate) fn make_hasher<Q, V, S>(hash_builder: &S) -> impl Fn(&(Q, V)) -> u64 + '_
+where
+    Q: Hash,
+    S: BuildHasher,
+{
+    move |val| make_hash::<Q, S>(hash_builder, &val.0)
+}
+
+/// Ensures that a single closure type across uses of this which, in turn prevents multiple
+/// instances of any functions like RawTable::reserve from being generated
+#[cfg_attr(feature = "inline-more", inline)]
+fn equivalent_key<Q, K, V>(k: &Q) -> impl Fn(&(K, V)) -> bool + '_
+where
+    Q: ?Sized + Equivalent<K>,
+{
+    move |x| k.equivalent(&x.0)
+}
+
+/// Ensures that a single closure type across uses of this which, in turn prevents multiple
+/// instances of any functions like RawTable::reserve from being generated
+#[cfg_attr(feature = "inline-more", inline)]
+fn equivalent<Q, K>(k: &Q) -> impl Fn(&K) -> bool + '_
+where
+    Q: ?Sized + Equivalent<K>,
+{
+    move |x| k.equivalent(x)
+}
+
+#[cfg(not(feature = "nightly"))]
+#[cfg_attr(feature = "inline-more", inline)]
+pub(crate) fn make_hash<Q, S>(hash_builder: &S, val: &Q) -> u64
+where
+    Q: Hash + ?Sized,
+    S: BuildHasher,
+{
+    use core::hash::Hasher;
+    let mut state = hash_builder.build_hasher();
+    val.hash(&mut state);
+    state.finish()
+}
+
+#[cfg(feature = "nightly")]
+#[cfg_attr(feature = "inline-more", inline)]
+pub(crate) fn make_hash<Q, S>(hash_builder: &S, val: &Q) -> u64
+where
+    Q: Hash + ?Sized,
+    S: BuildHasher,
+{
+    hash_builder.hash_one(val)
+}
+
+#[cfg(feature = "ahash")]
+impl<K, V> HashMap<K, V, DefaultHashBuilder> {
+    /// Creates an empty `HashMap`.
+    ///
+    /// The hash map is initially created with a capacity of 0, so it will not allocate until it
+    /// is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`], for example with
+    /// [`with_hasher`](HashMap::with_hasher) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
+    /// assert_eq!(map.len(), 0);
+    /// assert_eq!(map.capacity(), 0);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Creates an empty `HashMap` with the specified capacity.
+    ///
+    /// The hash map will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash map will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`], for example with
+    /// [`with_capacity_and_hasher`](HashMap::with_capacity_and_hasher) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
+    /// assert_eq!(map.len(), 0);
+    /// assert!(map.capacity() >= 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self::with_capacity_and_hasher(capacity, DefaultHashBuilder::default())
+    }
+}
+
+#[cfg(feature = "ahash")]
+impl<K, V, A: Allocator> HashMap<K, V, DefaultHashBuilder, A> {
+    /// Creates an empty `HashMap` using the given allocator.
+    ///
+    /// The hash map is initially created with a capacity of 0, so it will not allocate until it
+    /// is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`], for example with
+    /// [`with_hasher_in`](HashMap::with_hasher_in) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use bumpalo::Bump;
+    ///
+    /// let bump = Bump::new();
+    /// let mut map = HashMap::new_in(&bump);
+    ///
+    /// // The created HashMap holds none elements
+    /// assert_eq!(map.len(), 0);
+    ///
+    /// // The created HashMap also doesn't allocate memory
+    /// assert_eq!(map.capacity(), 0);
+    ///
+    /// // Now we insert element inside created HashMap
+    /// map.insert("One", 1);
+    /// // We can see that the HashMap holds 1 element
+    /// assert_eq!(map.len(), 1);
+    /// // And it also allocates some capacity
+    /// assert!(map.capacity() > 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn new_in(alloc: A) -> Self {
+        Self::with_hasher_in(DefaultHashBuilder::default(), alloc)
+    }
+
+    /// Creates an empty `HashMap` with the specified capacity using the given allocator.
+    ///
+    /// The hash map will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash map will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`], for example with
+    /// [`with_capacity_and_hasher_in`](HashMap::with_capacity_and_hasher_in) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use bumpalo::Bump;
+    ///
+    /// let bump = Bump::new();
+    /// let mut map = HashMap::with_capacity_in(5, &bump);
+    ///
+    /// // The created HashMap holds none elements
+    /// assert_eq!(map.len(), 0);
+    /// // But it can hold at least 5 elements without reallocating
+    /// let empty_map_capacity = map.capacity();
+    /// assert!(empty_map_capacity >= 5);
+    ///
+    /// // Now we insert some 5 elements inside created HashMap
+    /// map.insert("One",   1);
+    /// map.insert("Two",   2);
+    /// map.insert("Three", 3);
+    /// map.insert("Four",  4);
+    /// map.insert("Five",  5);
+    ///
+    /// // We can see that the HashMap holds 5 elements
+    /// assert_eq!(map.len(), 5);
+    /// // But its capacity isn't changed
+    /// assert_eq!(map.capacity(), empty_map_capacity)
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
+        Self::with_capacity_and_hasher_in(capacity, DefaultHashBuilder::default(), alloc)
+    }
+}
+
+impl<K, V, S> HashMap<K, V, S> {
+    /// Creates an empty `HashMap` which will use the given hash builder to hash
+    /// keys.
+    ///
+    /// The hash map is initially created with a capacity of 0, so it will not
+    /// allocate until it is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashMap to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut map = HashMap::with_hasher(s);
+    /// assert_eq!(map.len(), 0);
+    /// assert_eq!(map.capacity(), 0);
+    ///
+    /// map.insert(1, 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub const fn with_hasher(hash_builder: S) -> Self {
+        Self {
+            hash_builder,
+            table: RawTable::new(),
+        }
+    }
+
+    /// Creates an empty `HashMap` with the specified capacity, using `hash_builder`
+    /// to hash the keys.
+    ///
+    /// The hash map will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash map will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashMap to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut map = HashMap::with_capacity_and_hasher(10, s);
+    /// assert_eq!(map.len(), 0);
+    /// assert!(map.capacity() >= 10);
+    ///
+    /// map.insert(1, 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self {
+        Self {
+            hash_builder,
+            table: RawTable::with_capacity(capacity),
+        }
+    }
+}
+
+impl<K, V, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Returns a reference to the underlying allocator.
+    #[inline]
+    pub fn allocator(&self) -> &A {
+        self.table.allocator()
+    }
+
+    /// Creates an empty `HashMap` which will use the given hash builder to hash
+    /// keys. It will be allocated with the given allocator.
+    ///
+    /// The hash map is initially created with a capacity of 0, so it will not allocate until it
+    /// is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`].
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut map = HashMap::with_hasher(s);
+    /// map.insert(1, 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub const fn with_hasher_in(hash_builder: S, alloc: A) -> Self {
+        Self {
+            hash_builder,
+            table: RawTable::new_in(alloc),
+        }
+    }
+
+    /// Creates an empty `HashMap` with the specified capacity, using `hash_builder`
+    /// to hash the keys. It will be allocated with the given allocator.
+    ///
+    /// The hash map will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash map will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashMap` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashMap`].
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut map = HashMap::with_capacity_and_hasher(10, s);
+    /// map.insert(1, 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_and_hasher_in(capacity: usize, hash_builder: S, alloc: A) -> Self {
+        Self {
+            hash_builder,
+            table: RawTable::with_capacity_in(capacity, alloc),
+        }
+    }
+
+    /// Returns a reference to the map's [`BuildHasher`].
+    ///
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let hasher = DefaultHashBuilder::default();
+    /// let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
+    /// let hasher: &DefaultHashBuilder = map.hasher();
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn hasher(&self) -> &S {
+        &self.hash_builder
+    }
+
+    /// Returns the number of elements the map can hold without reallocating.
+    ///
+    /// This number is a lower bound; the `HashMap<K, V>` might be able to hold
+    /// more, but is guaranteed to be able to hold at least this many.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let map: HashMap<i32, i32> = HashMap::with_capacity(100);
+    /// assert_eq!(map.len(), 0);
+    /// assert!(map.capacity() >= 100);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn capacity(&self) -> usize {
+        self.table.capacity()
+    }
+
+    /// An iterator visiting all keys in arbitrary order.
+    /// The iterator element type is `&'a K`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    /// assert_eq!(map.len(), 3);
+    /// let mut vec: Vec<&str> = Vec::new();
+    ///
+    /// for key in map.keys() {
+    ///     println!("{}", key);
+    ///     vec.push(*key);
+    /// }
+    ///
+    /// // The `Keys` iterator produces keys in arbitrary order, so the
+    /// // keys must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, ["a", "b", "c"]);
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn keys(&self) -> Keys<'_, K, V> {
+        Keys { inner: self.iter() }
+    }
+
+    /// An iterator visiting all values in arbitrary order.
+    /// The iterator element type is `&'a V`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    /// assert_eq!(map.len(), 3);
+    /// let mut vec: Vec<i32> = Vec::new();
+    ///
+    /// for val in map.values() {
+    ///     println!("{}", val);
+    ///     vec.push(*val);
+    /// }
+    ///
+    /// // The `Values` iterator produces values in arbitrary order, so the
+    /// // values must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [1, 2, 3]);
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn values(&self) -> Values<'_, K, V> {
+        Values { inner: self.iter() }
+    }
+
+    /// An iterator visiting all values mutably in arbitrary order.
+    /// The iterator element type is `&'a mut V`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    ///
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    ///
+    /// for val in map.values_mut() {
+    ///     *val = *val + 10;
+    /// }
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// let mut vec: Vec<i32> = Vec::new();
+    ///
+    /// for val in map.values() {
+    ///     println!("{}", val);
+    ///     vec.push(*val);
+    /// }
+    ///
+    /// // The `Values` iterator produces values in arbitrary order, so the
+    /// // values must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [11, 12, 13]);
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
+        ValuesMut {
+            inner: self.iter_mut(),
+        }
+    }
+
+    /// An iterator visiting all key-value pairs in arbitrary order.
+    /// The iterator element type is `(&'a K, &'a V)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    /// assert_eq!(map.len(), 3);
+    /// let mut vec: Vec<(&str, i32)> = Vec::new();
+    ///
+    /// for (key, val) in map.iter() {
+    ///     println!("key: {} val: {}", key, val);
+    ///     vec.push((*key, *val));
+    /// }
+    ///
+    /// // The `Iter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3)]);
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn iter(&self) -> Iter<'_, K, V> {
+        // Here we tie the lifetime of self to the iter.
+        unsafe {
+            Iter {
+                inner: self.table.iter(),
+                marker: PhantomData,
+            }
+        }
+    }
+
+    /// An iterator visiting all key-value pairs in arbitrary order,
+    /// with mutable references to the values.
+    /// The iterator element type is `(&'a K, &'a mut V)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    ///
+    /// // Update all values
+    /// for (_, val) in map.iter_mut() {
+    ///     *val *= 2;
+    /// }
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// let mut vec: Vec<(&str, i32)> = Vec::new();
+    ///
+    /// for (key, val) in &map {
+    ///     println!("key: {} val: {}", key, val);
+    ///     vec.push((*key, *val));
+    /// }
+    ///
+    /// // The `Iter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [("a", 2), ("b", 4), ("c", 6)]);
+    ///
+    /// assert_eq!(map.len(), 3);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
+        // Here we tie the lifetime of self to the iter.
+        unsafe {
+            IterMut {
+                inner: self.table.iter(),
+                marker: PhantomData,
+            }
+        }
+    }
+
+    #[cfg(test)]
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn raw_capacity(&self) -> usize {
+        self.table.buckets()
+    }
+
+    /// Returns the number of elements in the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut a = HashMap::new();
+    /// assert_eq!(a.len(), 0);
+    /// a.insert(1, "a");
+    /// assert_eq!(a.len(), 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn len(&self) -> usize {
+        self.table.len()
+    }
+
+    /// Returns `true` if the map contains no elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut a = HashMap::new();
+    /// assert!(a.is_empty());
+    /// a.insert(1, "a");
+    /// assert!(!a.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Clears the map, returning all key-value pairs as an iterator. Keeps the
+    /// allocated memory for reuse.
+    ///
+    /// If the returned iterator is dropped before being fully consumed, it
+    /// drops the remaining key-value pairs. The returned iterator keeps a
+    /// mutable borrow on the vector to optimize its implementation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut a = HashMap::new();
+    /// a.insert(1, "a");
+    /// a.insert(2, "b");
+    /// let capacity_before_drain = a.capacity();
+    ///
+    /// for (k, v) in a.drain().take(1) {
+    ///     assert!(k == 1 || k == 2);
+    ///     assert!(v == "a" || v == "b");
+    /// }
+    ///
+    /// // As we can see, the map is empty and contains no element.
+    /// assert!(a.is_empty() && a.len() == 0);
+    /// // But map capacity is equal to old one.
+    /// assert_eq!(a.capacity(), capacity_before_drain);
+    ///
+    /// let mut a = HashMap::new();
+    /// a.insert(1, "a");
+    /// a.insert(2, "b");
+    ///
+    /// {   // Iterator is dropped without being consumed.
+    ///     let d = a.drain();
+    /// }
+    ///
+    /// // But the map is empty even if we do not use Drain iterator.
+    /// assert!(a.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn drain(&mut self) -> Drain<'_, K, V, A> {
+        Drain {
+            inner: self.table.drain(),
+        }
+    }
+
+    /// Retains only the elements specified by the predicate. Keeps the
+    /// allocated memory for reuse.
+    ///
+    /// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`.
+    /// The elements are visited in unsorted (and unspecified) order.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
+    /// assert_eq!(map.len(), 8);
+    ///
+    /// map.retain(|&k, _| k % 2 == 0);
+    ///
+    /// // We can see, that the number of elements inside map is changed.
+    /// assert_eq!(map.len(), 4);
+    ///
+    /// let mut vec: Vec<(i32, i32)> = map.iter().map(|(&k, &v)| (k, v)).collect();
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [(0, 0), (2, 20), (4, 40), (6, 60)]);
+    /// ```
+    pub fn retain<F>(&mut self, mut f: F)
+    where
+        F: FnMut(&K, &mut V) -> bool,
+    {
+        // Here we only use `iter` as a temporary, preventing use-after-free
+        unsafe {
+            for item in self.table.iter() {
+                let &mut (ref key, ref mut value) = item.as_mut();
+                if !f(key, value) {
+                    self.table.erase(item);
+                }
+            }
+        }
+    }
+
+    /// Drains elements which are true under the given predicate,
+    /// and returns an iterator over the removed items.
+    ///
+    /// In other words, move all pairs `(k, v)` such that `f(&k, &mut v)` returns `true` out
+    /// into another iterator.
+    ///
+    /// Note that `extract_if` lets you mutate every value in the filter closure, regardless of
+    /// whether you choose to keep or remove it.
+    ///
+    /// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating
+    /// or the iteration short-circuits, then the remaining elements will be retained.
+    /// Use [`retain()`] with a negated predicate if you do not need the returned iterator.
+    ///
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
+    ///
+    /// let drained: HashMap<i32, i32> = map.extract_if(|k, _v| k % 2 == 0).collect();
+    ///
+    /// let mut evens = drained.keys().cloned().collect::<Vec<_>>();
+    /// let mut odds = map.keys().cloned().collect::<Vec<_>>();
+    /// evens.sort();
+    /// odds.sort();
+    ///
+    /// assert_eq!(evens, vec![0, 2, 4, 6]);
+    /// assert_eq!(odds, vec![1, 3, 5, 7]);
+    ///
+    /// let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
+    ///
+    /// {   // Iterator is dropped without being consumed.
+    ///     let d = map.extract_if(|k, _v| k % 2 != 0);
+    /// }
+    ///
+    /// // ExtractIf was not exhausted, therefore no elements were drained.
+    /// assert_eq!(map.len(), 8);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, K, V, F, A>
+    where
+        F: FnMut(&K, &mut V) -> bool,
+    {
+        ExtractIf {
+            f,
+            inner: ExtractIfInner {
+                iter: unsafe { self.table.iter() },
+                table: &mut self.table,
+            },
+        }
+    }
+
+    /// Clears the map, removing all key-value pairs. Keeps the allocated memory
+    /// for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut a = HashMap::new();
+    /// a.insert(1, "a");
+    /// let capacity_before_clear = a.capacity();
+    ///
+    /// a.clear();
+    ///
+    /// // Map is empty.
+    /// assert!(a.is_empty());
+    /// // But map capacity is equal to old one.
+    /// assert_eq!(a.capacity(), capacity_before_clear);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn clear(&mut self) {
+        self.table.clear();
+    }
+
+    /// Creates a consuming iterator visiting all the keys in arbitrary order.
+    /// The map cannot be used after calling this.
+    /// The iterator element type is `K`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    ///
+    /// let mut vec: Vec<&str> = map.into_keys().collect();
+    ///
+    /// // The `IntoKeys` iterator produces keys in arbitrary order, so the
+    /// // keys must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, ["a", "b", "c"]);
+    /// ```
+    #[inline]
+    pub fn into_keys(self) -> IntoKeys<K, V, A> {
+        IntoKeys {
+            inner: self.into_iter(),
+        }
+    }
+
+    /// Creates a consuming iterator visiting all the values in arbitrary order.
+    /// The map cannot be used after calling this.
+    /// The iterator element type is `V`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert("a", 1);
+    /// map.insert("b", 2);
+    /// map.insert("c", 3);
+    ///
+    /// let mut vec: Vec<i32> = map.into_values().collect();
+    ///
+    /// // The `IntoValues` iterator produces values in arbitrary order, so
+    /// // the values must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [1, 2, 3]);
+    /// ```
+    #[inline]
+    pub fn into_values(self) -> IntoValues<K, V, A> {
+        IntoValues {
+            inner: self.into_iter(),
+        }
+    }
+}
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Reserves capacity for at least `additional` more elements to be inserted
+    /// in the `HashMap`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity exceeds [`isize::MAX`] bytes and [`abort`] the program
+    /// in case of allocation error. Use [`try_reserve`](HashMap::try_reserve) instead
+    /// if you want to handle memory allocation failure.
+    ///
+    /// [`isize::MAX`]: https://doc.rust-lang.org/std/primitive.isize.html
+    /// [`abort`]: https://doc.rust-lang.org/alloc/alloc/fn.handle_alloc_error.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
+    /// // Map is empty and doesn't allocate memory
+    /// assert_eq!(map.capacity(), 0);
+    ///
+    /// map.reserve(10);
+    ///
+    /// // And now map can hold at least 10 elements
+    /// assert!(map.capacity() >= 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn reserve(&mut self, additional: usize) {
+        self.table
+            .reserve(additional, make_hasher::<_, V, S>(&self.hash_builder));
+    }
+
+    /// Tries to reserve capacity for at least `additional` more elements to be inserted
+    /// in the given `HashMap<K,V>`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Errors
+    ///
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, isize> = HashMap::new();
+    /// // Map is empty and doesn't allocate memory
+    /// assert_eq!(map.capacity(), 0);
+    ///
+    /// map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
+    ///
+    /// // And now map can hold at least 10 elements
+    /// assert!(map.capacity() >= 10);
+    /// ```
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned:
+    /// ```
+    /// # fn test() {
+    /// use hashbrown::HashMap;
+    /// use hashbrown::TryReserveError;
+    /// let mut map: HashMap<i32, i32> = HashMap::new();
+    ///
+    /// match map.try_reserve(usize::MAX) {
+    ///     Err(error) => match error {
+    ///         TryReserveError::CapacityOverflow => {}
+    ///         _ => panic!("TryReserveError::AllocError ?"),
+    ///     },
+    ///     _ => panic!(),
+    /// }
+    /// # }
+    /// # fn main() {
+    /// #     #[cfg(not(miri))]
+    /// #     test()
+    /// # }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.table
+            .try_reserve(additional, make_hasher::<_, V, S>(&self.hash_builder))
+    }
+
+    /// Shrinks the capacity of the map as much as possible. It will drop
+    /// down as much as possible while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
+    /// map.insert(1, 2);
+    /// map.insert(3, 4);
+    /// assert!(map.capacity() >= 100);
+    /// map.shrink_to_fit();
+    /// assert!(map.capacity() >= 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn shrink_to_fit(&mut self) {
+        self.table
+            .shrink_to(0, make_hasher::<_, V, S>(&self.hash_builder));
+    }
+
+    /// Shrinks the capacity of the map with a lower limit. It will drop
+    /// down no lower than the supplied limit while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// This function does nothing if the current capacity is smaller than the
+    /// supplied minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
+    /// map.insert(1, 2);
+    /// map.insert(3, 4);
+    /// assert!(map.capacity() >= 100);
+    /// map.shrink_to(10);
+    /// assert!(map.capacity() >= 10);
+    /// map.shrink_to(0);
+    /// assert!(map.capacity() >= 2);
+    /// map.shrink_to(10);
+    /// assert!(map.capacity() >= 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.table
+            .shrink_to(min_capacity, make_hasher::<_, V, S>(&self.hash_builder));
+    }
+
+    /// Gets the given key's corresponding entry in the map for in-place manipulation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut letters = HashMap::new();
+    ///
+    /// for ch in "a short treatise on fungi".chars() {
+    ///     let counter = letters.entry(ch).or_insert(0);
+    ///     *counter += 1;
+    /// }
+    ///
+    /// assert_eq!(letters[&'s'], 2);
+    /// assert_eq!(letters[&'t'], 3);
+    /// assert_eq!(letters[&'u'], 1);
+    /// assert_eq!(letters.get(&'y'), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn entry(&mut self, key: K) -> Entry<'_, K, V, S, A> {
+        let hash = make_hash::<K, S>(&self.hash_builder, &key);
+        if let Some(elem) = self.table.find(hash, equivalent_key(&key)) {
+            Entry::Occupied(OccupiedEntry {
+                hash,
+                key: Some(key),
+                elem,
+                table: self,
+            })
+        } else {
+            Entry::Vacant(VacantEntry {
+                hash,
+                key,
+                table: self,
+            })
+        }
+    }
+
+    /// Gets the given key's corresponding entry by reference in the map for in-place manipulation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut words: HashMap<String, usize> = HashMap::new();
+    /// let source = ["poneyland", "horseyland", "poneyland", "poneyland"];
+    /// for (i, &s) in source.iter().enumerate() {
+    ///     let counter = words.entry_ref(s).or_insert(0);
+    ///     *counter += 1;
+    /// }
+    ///
+    /// assert_eq!(words["poneyland"], 3);
+    /// assert_eq!(words["horseyland"], 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn entry_ref<'a, 'b, Q: ?Sized>(&'a mut self, key: &'b Q) -> EntryRef<'a, 'b, K, Q, V, S, A>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        let hash = make_hash::<Q, S>(&self.hash_builder, key);
+        if let Some(elem) = self.table.find(hash, equivalent_key(key)) {
+            EntryRef::Occupied(OccupiedEntryRef {
+                hash,
+                key: Some(KeyOrRef::Borrowed(key)),
+                elem,
+                table: self,
+            })
+        } else {
+            EntryRef::Vacant(VacantEntryRef {
+                hash,
+                key: KeyOrRef::Borrowed(key),
+                table: self,
+            })
+        }
+    }
+
+    /// Returns a reference to the value corresponding to the key.
+    ///
+    /// The key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// assert_eq!(map.get(&1), Some(&"a"));
+    /// assert_eq!(map.get(&2), None);
+    /// ```
+    #[inline]
+    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.get_inner(k) {
+            Some((_, v)) => Some(v),
+            None => None,
+        }
+    }
+
+    /// Returns the key-value pair corresponding to the supplied key.
+    ///
+    /// The supplied key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
+    /// assert_eq!(map.get_key_value(&2), None);
+    /// ```
+    #[inline]
+    pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.get_inner(k) {
+            Some((key, value)) => Some((key, value)),
+            None => None,
+        }
+    }
+
+    #[inline]
+    fn get_inner<Q: ?Sized>(&self, k: &Q) -> Option<&(K, V)>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        if self.table.is_empty() {
+            None
+        } else {
+            let hash = make_hash::<Q, S>(&self.hash_builder, k);
+            self.table.get(hash, equivalent_key(k))
+        }
+    }
+
+    /// Returns the key-value pair corresponding to the supplied key, with a mutable reference to value.
+    ///
+    /// The supplied key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// let (k, v) = map.get_key_value_mut(&1).unwrap();
+    /// assert_eq!(k, &1);
+    /// assert_eq!(v, &mut "a");
+    /// *v = "b";
+    /// assert_eq!(map.get_key_value_mut(&1), Some((&1, &mut "b")));
+    /// assert_eq!(map.get_key_value_mut(&2), None);
+    /// ```
+    #[inline]
+    pub fn get_key_value_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<(&K, &mut V)>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.get_inner_mut(k) {
+            Some(&mut (ref key, ref mut value)) => Some((key, value)),
+            None => None,
+        }
+    }
+
+    /// Returns `true` if the map contains a value for the specified key.
+    ///
+    /// The key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// assert_eq!(map.contains_key(&1), true);
+    /// assert_eq!(map.contains_key(&2), false);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        self.get_inner(k).is_some()
+    }
+
+    /// Returns a mutable reference to the value corresponding to the key.
+    ///
+    /// The key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, "a");
+    /// if let Some(x) = map.get_mut(&1) {
+    ///     *x = "b";
+    /// }
+    /// assert_eq!(map[&1], "b");
+    ///
+    /// assert_eq!(map.get_mut(&2), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.get_inner_mut(k) {
+            Some(&mut (_, ref mut v)) => Some(v),
+            None => None,
+        }
+    }
+
+    #[inline]
+    fn get_inner_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut (K, V)>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        if self.table.is_empty() {
+            None
+        } else {
+            let hash = make_hash::<Q, S>(&self.hash_builder, k);
+            self.table.get_mut(hash, equivalent_key(k))
+        }
+    }
+
+    /// Attempts to get mutable references to `N` values in the map at once.
+    ///
+    /// Returns an array of length `N` with the results of each query. For soundness, at most one
+    /// mutable reference will be returned to any value. `None` will be returned if any of the
+    /// keys are duplicates or missing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Library of Congress",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         &mut 1807,
+    ///         &mut 1800,
+    ///     ]),
+    /// );
+    ///
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "New York Public Library",
+    /// ]);
+    /// assert_eq!(got, None);
+    ///
+    /// // Duplicate keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Athenæum",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    pub fn get_many_mut<Q: ?Sized, const N: usize>(&mut self, ks: [&Q; N]) -> Option<[&'_ mut V; N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        self.get_many_mut_inner(ks).map(|res| res.map(|(_, v)| v))
+    }
+
+    /// Attempts to get mutable references to `N` values in the map at once, without validating that
+    /// the values are unique.
+    ///
+    /// Returns an array of length `N` with the results of each query. `None` will be returned if
+    /// any of the keys are missing.
+    ///
+    /// For a safe alternative see [`get_many_mut`](`HashMap::get_many_mut`).
+    ///
+    /// # Safety
+    ///
+    /// Calling this method with overlapping keys is *[undefined behavior]* even if the resulting
+    /// references are not used.
+    ///
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "Library of Congress",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         &mut 1807,
+    ///         &mut 1800,
+    ///     ]),
+    /// );
+    ///
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_mut([
+    ///     "Athenæum",
+    ///     "New York Public Library",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    pub unsafe fn get_many_unchecked_mut<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[&'_ mut V; N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        self.get_many_unchecked_mut_inner(ks)
+            .map(|res| res.map(|(_, v)| v))
+    }
+
+    /// Attempts to get mutable references to `N` values in the map at once, with immutable
+    /// references to the corresponding keys.
+    ///
+    /// Returns an array of length `N` with the results of each query. For soundness, at most one
+    /// mutable reference will be returned to any value. `None` will be returned if any of the keys
+    /// are duplicates or missing.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_key_value_mut([
+    ///     "Bodleian Library",
+    ///     "Herzogin-Anna-Amalia-Bibliothek",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         (&"Bodleian Library".to_string(), &mut 1602),
+    ///         (&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691),
+    ///     ]),
+    /// );
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_key_value_mut([
+    ///     "Bodleian Library",
+    ///     "Gewandhaus",
+    /// ]);
+    /// assert_eq!(got, None);
+    ///
+    /// // Duplicate keys result in None
+    /// let got = libraries.get_many_key_value_mut([
+    ///     "Bodleian Library",
+    ///     "Herzogin-Anna-Amalia-Bibliothek",
+    ///     "Herzogin-Anna-Amalia-Bibliothek",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    pub fn get_many_key_value_mut<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[(&'_ K, &'_ mut V); N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        self.get_many_mut_inner(ks)
+            .map(|res| res.map(|(k, v)| (&*k, v)))
+    }
+
+    /// Attempts to get mutable references to `N` values in the map at once, with immutable
+    /// references to the corresponding keys, without validating that the values are unique.
+    ///
+    /// Returns an array of length `N` with the results of each query. `None` will be returned if
+    /// any of the keys are missing.
+    ///
+    /// For a safe alternative see [`get_many_key_value_mut`](`HashMap::get_many_key_value_mut`).
+    ///
+    /// # Safety
+    ///
+    /// Calling this method with overlapping keys is *[undefined behavior]* even if the resulting
+    /// references are not used.
+    ///
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut libraries = HashMap::new();
+    /// libraries.insert("Bodleian Library".to_string(), 1602);
+    /// libraries.insert("Athenæum".to_string(), 1807);
+    /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
+    /// libraries.insert("Library of Congress".to_string(), 1800);
+    ///
+    /// let got = libraries.get_many_key_value_mut([
+    ///     "Bodleian Library",
+    ///     "Herzogin-Anna-Amalia-Bibliothek",
+    /// ]);
+    /// assert_eq!(
+    ///     got,
+    ///     Some([
+    ///         (&"Bodleian Library".to_string(), &mut 1602),
+    ///         (&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691),
+    ///     ]),
+    /// );
+    /// // Missing keys result in None
+    /// let got = libraries.get_many_key_value_mut([
+    ///     "Bodleian Library",
+    ///     "Gewandhaus",
+    /// ]);
+    /// assert_eq!(got, None);
+    /// ```
+    pub unsafe fn get_many_key_value_unchecked_mut<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[(&'_ K, &'_ mut V); N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        self.get_many_unchecked_mut_inner(ks)
+            .map(|res| res.map(|(k, v)| (&*k, v)))
+    }
+
+    fn get_many_mut_inner<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[&'_ mut (K, V); N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        let hashes = self.build_hashes_inner(ks);
+        self.table
+            .get_many_mut(hashes, |i, (k, _)| ks[i].equivalent(k))
+    }
+
+    unsafe fn get_many_unchecked_mut_inner<Q: ?Sized, const N: usize>(
+        &mut self,
+        ks: [&Q; N],
+    ) -> Option<[&'_ mut (K, V); N]>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        let hashes = self.build_hashes_inner(ks);
+        self.table
+            .get_many_unchecked_mut(hashes, |i, (k, _)| ks[i].equivalent(k))
+    }
+
+    fn build_hashes_inner<Q: ?Sized, const N: usize>(&self, ks: [&Q; N]) -> [u64; N]
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        let mut hashes = [0_u64; N];
+        for i in 0..N {
+            hashes[i] = make_hash::<Q, S>(&self.hash_builder, ks[i]);
+        }
+        hashes
+    }
+
+    /// Inserts a key-value pair into the map.
+    ///
+    /// If the map did not have this key present, [`None`] is returned.
+    ///
+    /// If the map did have this key present, the value is updated, and the old
+    /// value is returned. The key is not updated, though; this matters for
+    /// types that can be `==` without being identical. See the [`std::collections`]
+    /// [module-level documentation] for more.
+    ///
+    /// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
+    /// [`std::collections`]: https://doc.rust-lang.org/std/collections/index.html
+    /// [module-level documentation]: https://doc.rust-lang.org/std/collections/index.html#insert-and-complex-keys
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// assert_eq!(map.insert(37, "a"), None);
+    /// assert_eq!(map.is_empty(), false);
+    ///
+    /// map.insert(37, "b");
+    /// assert_eq!(map.insert(37, "c"), Some("b"));
+    /// assert_eq!(map[&37], "c");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, k: K, v: V) -> Option<V> {
+        let hash = make_hash::<K, S>(&self.hash_builder, &k);
+        let hasher = make_hasher::<_, V, S>(&self.hash_builder);
+        match self
+            .table
+            .find_or_find_insert_slot(hash, equivalent_key(&k), hasher)
+        {
+            Ok(bucket) => Some(mem::replace(unsafe { &mut bucket.as_mut().1 }, v)),
+            Err(slot) => {
+                unsafe {
+                    self.table.insert_in_slot(hash, slot, (k, v));
+                }
+                None
+            }
+        }
+    }
+
+    /// Insert a key-value pair into the map without checking
+    /// if the key already exists in the map.
+    ///
+    /// Returns a reference to the key and value just inserted.
+    ///
+    /// This operation is safe if a key does not exist in the map.
+    ///
+    /// However, if a key exists in the map already, the behavior is unspecified:
+    /// this operation may panic, loop forever, or any following operation with the map
+    /// may panic, loop forever or return arbitrary result.
+    ///
+    /// That said, this operation (and following operations) are guaranteed to
+    /// not violate memory safety.
+    ///
+    /// This operation is faster than regular insert, because it does not perform
+    /// lookup before insertion.
+    ///
+    /// This operation is useful during initial population of the map.
+    /// For example, when constructing a map from another map, we know
+    /// that keys are unique.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map1 = HashMap::new();
+    /// assert_eq!(map1.insert(1, "a"), None);
+    /// assert_eq!(map1.insert(2, "b"), None);
+    /// assert_eq!(map1.insert(3, "c"), None);
+    /// assert_eq!(map1.len(), 3);
+    ///
+    /// let mut map2 = HashMap::new();
+    ///
+    /// for (key, value) in map1.into_iter() {
+    ///     map2.insert_unique_unchecked(key, value);
+    /// }
+    ///
+    /// let (key, value) = map2.insert_unique_unchecked(4, "d");
+    /// assert_eq!(key, &4);
+    /// assert_eq!(value, &mut "d");
+    /// *value = "e";
+    ///
+    /// assert_eq!(map2[&1], "a");
+    /// assert_eq!(map2[&2], "b");
+    /// assert_eq!(map2[&3], "c");
+    /// assert_eq!(map2[&4], "e");
+    /// assert_eq!(map2.len(), 4);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V) {
+        let hash = make_hash::<K, S>(&self.hash_builder, &k);
+        let bucket = self
+            .table
+            .insert(hash, (k, v), make_hasher::<_, V, S>(&self.hash_builder));
+        let (k_ref, v_ref) = unsafe { bucket.as_mut() };
+        (k_ref, v_ref)
+    }
+
+    /// Tries to insert a key-value pair into the map, and returns
+    /// a mutable reference to the value in the entry.
+    ///
+    /// # Errors
+    ///
+    /// If the map already had this key present, nothing is updated, and
+    /// an error containing the occupied entry and the value is returned.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::OccupiedError;
+    ///
+    /// let mut map = HashMap::new();
+    /// assert_eq!(map.try_insert(37, "a").unwrap(), &"a");
+    ///
+    /// match map.try_insert(37, "b") {
+    ///     Err(OccupiedError { entry, value }) => {
+    ///         assert_eq!(entry.key(), &37);
+    ///         assert_eq!(entry.get(), &"a");
+    ///         assert_eq!(value, "b");
+    ///     }
+    ///     _ => panic!()
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn try_insert(
+        &mut self,
+        key: K,
+        value: V,
+    ) -> Result<&mut V, OccupiedError<'_, K, V, S, A>> {
+        match self.entry(key) {
+            Entry::Occupied(entry) => Err(OccupiedError { entry, value }),
+            Entry::Vacant(entry) => Ok(entry.insert(value)),
+        }
+    }
+
+    /// Removes a key from the map, returning the value at the key if the key
+    /// was previously in the map. Keeps the allocated memory for reuse.
+    ///
+    /// The key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.insert(1, "a");
+    ///
+    /// assert_eq!(map.remove(&1), Some("a"));
+    /// assert_eq!(map.remove(&1), None);
+    ///
+    /// // Now map holds none elements
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.remove_entry(k) {
+            Some((_, v)) => Some(v),
+            None => None,
+        }
+    }
+
+    /// Removes a key from the map, returning the stored key and value if the
+    /// key was previously in the map. Keeps the allocated memory for reuse.
+    ///
+    /// The key may be any borrowed form of the map's key type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the key type.
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.insert(1, "a");
+    ///
+    /// assert_eq!(map.remove_entry(&1), Some((1, "a")));
+    /// assert_eq!(map.remove(&1), None);
+    ///
+    /// // Now map hold none elements
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
+    where
+        Q: Hash + Equivalent<K>,
+    {
+        let hash = make_hash::<Q, S>(&self.hash_builder, k);
+        self.table.remove_entry(hash, equivalent_key(k))
+    }
+}
+
+impl<K, V, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Creates a raw entry builder for the HashMap.
+    ///
+    /// Raw entries provide the lowest level of control for searching and
+    /// manipulating a map. They must be manually initialized with a hash and
+    /// then manually searched. After this, insertions into a vacant entry
+    /// still require an owned key to be provided.
+    ///
+    /// Raw entries are useful for such exotic situations as:
+    ///
+    /// * Hash memoization
+    /// * Deferring the creation of an owned key until it is known to be required
+    /// * Using a search key that doesn't work with the Borrow trait
+    /// * Using custom comparison logic without newtype wrappers
+    ///
+    /// Because raw entries provide much more low-level control, it's much easier
+    /// to put the HashMap into an inconsistent state which, while memory-safe,
+    /// will cause the map to produce seemingly random results. Higher-level and
+    /// more foolproof APIs like `entry` should be preferred when possible.
+    ///
+    /// In particular, the hash used to initialized the raw entry must still be
+    /// consistent with the hash of the key that is ultimately stored in the entry.
+    /// This is because implementations of HashMap may need to recompute hashes
+    /// when resizing, at which point only the keys are available.
+    ///
+    /// Raw entries give mutable access to the keys. This must not be used
+    /// to modify how the key would compare or hash, as the map will not re-evaluate
+    /// where the key should go, meaning the keys may become "lost" if their
+    /// location does not reflect their state. For instance, if you change a key
+    /// so that the map now contains keys which compare equal, search may start
+    /// acting erratically, with two keys randomly masking each other. Implementations
+    /// are free to assume this doesn't happen (within the limits of memory-safety).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map = HashMap::new();
+    /// map.extend([("a", 100), ("b", 200), ("c", 300)]);
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// // Existing key (insert and update)
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => unreachable!(),
+    ///     RawEntryMut::Occupied(mut view) => {
+    ///         assert_eq!(view.get(), &100);
+    ///         let v = view.get_mut();
+    ///         let new_v = (*v) * 10;
+    ///         *v = new_v;
+    ///         assert_eq!(view.insert(1111), 1000);
+    ///     }
+    /// }
+    ///
+    /// assert_eq!(map[&"a"], 1111);
+    /// assert_eq!(map.len(), 3);
+    ///
+    /// // Existing key (take)
+    /// let hash = compute_hash(map.hasher(), &"c");
+    /// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
+    ///     RawEntryMut::Vacant(_) => unreachable!(),
+    ///     RawEntryMut::Occupied(view) => {
+    ///         assert_eq!(view.remove_entry(), ("c", 300));
+    ///     }
+    /// }
+    /// assert_eq!(map.raw_entry().from_key(&"c"), None);
+    /// assert_eq!(map.len(), 2);
+    ///
+    /// // Nonexistent key (insert and update)
+    /// let key = "d";
+    /// let hash = compute_hash(map.hasher(), &key);
+    /// match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
+    ///     RawEntryMut::Occupied(_) => unreachable!(),
+    ///     RawEntryMut::Vacant(view) => {
+    ///         let (k, value) = view.insert("d", 4000);
+    ///         assert_eq!((*k, *value), ("d", 4000));
+    ///         *value = 40000;
+    ///     }
+    /// }
+    /// assert_eq!(map[&"d"], 40000);
+    /// assert_eq!(map.len(), 3);
+    ///
+    /// match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
+    ///     RawEntryMut::Vacant(_) => unreachable!(),
+    ///     RawEntryMut::Occupied(view) => {
+    ///         assert_eq!(view.remove_entry(), ("d", 40000));
+    ///     }
+    /// }
+    /// assert_eq!(map.get(&"d"), None);
+    /// assert_eq!(map.len(), 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<'_, K, V, S, A> {
+        RawEntryBuilderMut { map: self }
+    }
+
+    /// Creates a raw immutable entry builder for the HashMap.
+    ///
+    /// Raw entries provide the lowest level of control for searching and
+    /// manipulating a map. They must be manually initialized with a hash and
+    /// then manually searched.
+    ///
+    /// This is useful for
+    /// * Hash memoization
+    /// * Using a search key that doesn't work with the Borrow trait
+    /// * Using custom comparison logic without newtype wrappers
+    ///
+    /// Unless you are in such a situation, higher-level and more foolproof APIs like
+    /// `get` should be preferred.
+    ///
+    /// Immutable raw entries have very limited use; you might instead want `raw_entry_mut`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.extend([("a", 100), ("b", 200), ("c", 300)]);
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// for k in ["a", "b", "c", "d", "e", "f"] {
+    ///     let hash = compute_hash(map.hasher(), k);
+    ///     let v = map.get(&k).cloned();
+    ///     let kv = v.as_ref().map(|v| (&k, v));
+    ///
+    ///     println!("Key: {} and value: {:?}", k, v);
+    ///
+    ///     assert_eq!(map.raw_entry().from_key(&k), kv);
+    ///     assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
+    ///     assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_entry(&self) -> RawEntryBuilder<'_, K, V, S, A> {
+        RawEntryBuilder { map: self }
+    }
+
+    /// Returns a reference to the [`RawTable`] used underneath [`HashMap`].
+    /// This function is only available if the `raw` feature of the crate is enabled.
+    ///
+    /// See [`raw_table_mut`] for more.
+    ///
+    /// [`raw_table_mut`]: Self::raw_table_mut
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_table(&self) -> &RawTable<(K, V), A> {
+        &self.table
+    }
+
+    /// Returns a mutable reference to the [`RawTable`] used underneath [`HashMap`].
+    /// This function is only available if the `raw` feature of the crate is enabled.
+    ///
+    /// # Note
+    ///
+    /// Calling this function is safe, but using the raw hash table API may require
+    /// unsafe functions or blocks.
+    ///
+    /// `RawTable` API gives the lowest level of control under the map that can be useful
+    /// for extending the HashMap's API, but may lead to *[undefined behavior]*.
+    ///
+    /// [`HashMap`]: struct.HashMap.html
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.extend([("a", 10), ("b", 20), ("c", 30)]);
+    /// assert_eq!(map.len(), 3);
+    ///
+    /// // Let's imagine that we have a value and a hash of the key, but not the key itself.
+    /// // However, if you want to remove the value from the map by hash and value, and you
+    /// // know exactly that the value is unique, then you can create a function like this:
+    /// fn remove_by_hash<K, V, S, F>(
+    ///     map: &mut HashMap<K, V, S>,
+    ///     hash: u64,
+    ///     is_match: F,
+    /// ) -> Option<(K, V)>
+    /// where
+    ///     F: Fn(&(K, V)) -> bool,
+    /// {
+    ///     let raw_table = map.raw_table_mut();
+    ///     match raw_table.find(hash, is_match) {
+    ///         Some(bucket) => Some(unsafe { raw_table.remove(bucket).0 }),
+    ///         None => None,
+    ///     }
+    /// }
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let hash = compute_hash(map.hasher(), "a");
+    /// assert_eq!(remove_by_hash(&mut map, hash, |(_, v)| *v == 10), Some(("a", 10)));
+    /// assert_eq!(map.get(&"a"), None);
+    /// assert_eq!(map.len(), 2);
+    /// ```
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_table_mut(&mut self) -> &mut RawTable<(K, V), A> {
+        &mut self.table
+    }
+}
+
+impl<K, V, S, A> PartialEq for HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    V: PartialEq,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn eq(&self, other: &Self) -> bool {
+        if self.len() != other.len() {
+            return false;
+        }
+
+        self.iter()
+            .all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
+    }
+}
+
+impl<K, V, S, A> Eq for HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    V: Eq,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<K, V, S, A> Debug for HashMap<K, V, S, A>
+where
+    K: Debug,
+    V: Debug,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_map().entries(self.iter()).finish()
+    }
+}
+
+impl<K, V, S, A> Default for HashMap<K, V, S, A>
+where
+    S: Default,
+    A: Default + Allocator,
+{
+    /// Creates an empty `HashMap<K, V, S, A>`, with the `Default` value for the hasher and allocator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// // You can specify all types of HashMap, including hasher and allocator.
+    /// // Created map is empty and don't allocate memory
+    /// let map: HashMap<u32, String> = Default::default();
+    /// assert_eq!(map.capacity(), 0);
+    /// let map: HashMap<u32, String, RandomState> = HashMap::default();
+    /// assert_eq!(map.capacity(), 0);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn default() -> Self {
+        Self::with_hasher_in(Default::default(), Default::default())
+    }
+}
+
+impl<K, Q: ?Sized, V, S, A> Index<&Q> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    Q: Hash + Equivalent<K>,
+    S: BuildHasher,
+    A: Allocator,
+{
+    type Output = V;
+
+    /// Returns a reference to the value corresponding to the supplied key.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the key is not present in the `HashMap`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let map: HashMap<_, _> = [("a", "One"), ("b", "Two")].into();
+    ///
+    /// assert_eq!(map[&"a"], "One");
+    /// assert_eq!(map[&"b"], "Two");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn index(&self, key: &Q) -> &V {
+        self.get(key).expect("no entry found for key")
+    }
+}
+
+// The default hasher is used to match the std implementation signature
+#[cfg(feature = "ahash")]
+impl<K, V, A, const N: usize> From<[(K, V); N]> for HashMap<K, V, DefaultHashBuilder, A>
+where
+    K: Eq + Hash,
+    A: Default + Allocator,
+{
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let map1 = HashMap::from([(1, 2), (3, 4)]);
+    /// let map2: HashMap<_, _> = [(1, 2), (3, 4)].into();
+    /// assert_eq!(map1, map2);
+    /// ```
+    fn from(arr: [(K, V); N]) -> Self {
+        arr.into_iter().collect()
+    }
+}
+
+/// An iterator over the entries of a `HashMap` in arbitrary order.
+/// The iterator element type is `(&'a K, &'a V)`.
+///
+/// This `struct` is created by the [`iter`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`iter`]: struct.HashMap.html#method.iter
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut iter = map.iter();
+/// let mut vec = vec![iter.next(), iter.next(), iter.next()];
+///
+/// // The `Iter` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some((&1, &"a")), Some((&2, &"b")), Some((&3, &"c"))]);
+///
+/// // It is fused iterator
+/// assert_eq!(iter.next(), None);
+/// assert_eq!(iter.next(), None);
+/// ```
+pub struct Iter<'a, K, V> {
+    inner: RawIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
+impl<K, V> Clone for Iter<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Iter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Debug, V: Debug> fmt::Debug for Iter<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+/// A mutable iterator over the entries of a `HashMap` in arbitrary order.
+/// The iterator element type is `(&'a K, &'a mut V)`.
+///
+/// This `struct` is created by the [`iter_mut`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`iter_mut`]: struct.HashMap.html#method.iter_mut
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let mut map: HashMap<_, _> = [(1, "One".to_owned()), (2, "Two".into())].into();
+///
+/// let mut iter = map.iter_mut();
+/// iter.next().map(|(_, v)| v.push_str(" Mississippi"));
+/// iter.next().map(|(_, v)| v.push_str(" Mississippi"));
+///
+/// // It is fused iterator
+/// assert_eq!(iter.next(), None);
+/// assert_eq!(iter.next(), None);
+///
+/// assert_eq!(map.get(&1).unwrap(), &"One Mississippi".to_owned());
+/// assert_eq!(map.get(&2).unwrap(), &"Two Mississippi".to_owned());
+/// ```
+pub struct IterMut<'a, K, V> {
+    inner: RawIter<(K, V)>,
+    // To ensure invariance with respect to V
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+// We override the default Send impl which has K: Sync instead of K: Send. Both
+// are correct, but this one is more general since it allows keys which
+// implement Send but not Sync.
+unsafe impl<K: Send, V: Send> Send for IterMut<'_, K, V> {}
+
+impl<K, V> IterMut<'_, K, V> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn iter(&self) -> Iter<'_, K, V> {
+        Iter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+/// An owning iterator over the entries of a `HashMap` in arbitrary order.
+/// The iterator element type is `(K, V)`.
+///
+/// This `struct` is created by the [`into_iter`] method on [`HashMap`]
+/// (provided by the [`IntoIterator`] trait). See its documentation for more.
+/// The map cannot be used after calling that method.
+///
+/// [`into_iter`]: struct.HashMap.html#method.into_iter
+/// [`HashMap`]: struct.HashMap.html
+/// [`IntoIterator`]: https://doc.rust-lang.org/core/iter/trait.IntoIterator.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut iter = map.into_iter();
+/// let mut vec = vec![iter.next(), iter.next(), iter.next()];
+///
+/// // The `IntoIter` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some((1, "a")), Some((2, "b")), Some((3, "c"))]);
+///
+/// // It is fused iterator
+/// assert_eq!(iter.next(), None);
+/// assert_eq!(iter.next(), None);
+/// ```
+pub struct IntoIter<K, V, A: Allocator = Global> {
+    inner: RawIntoIter<(K, V), A>,
+}
+
+impl<K, V, A: Allocator> IntoIter<K, V, A> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn iter(&self) -> Iter<'_, K, V> {
+        Iter {
+            inner: self.inner.iter(),
+            marker: PhantomData,
+        }
+    }
+}
+
+/// An owning iterator over the keys of a `HashMap` in arbitrary order.
+/// The iterator element type is `K`.
+///
+/// This `struct` is created by the [`into_keys`] method on [`HashMap`].
+/// See its documentation for more.
+/// The map cannot be used after calling that method.
+///
+/// [`into_keys`]: struct.HashMap.html#method.into_keys
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut keys = map.into_keys();
+/// let mut vec = vec![keys.next(), keys.next(), keys.next()];
+///
+/// // The `IntoKeys` iterator produces keys in arbitrary order, so the
+/// // keys must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some(1), Some(2), Some(3)]);
+///
+/// // It is fused iterator
+/// assert_eq!(keys.next(), None);
+/// assert_eq!(keys.next(), None);
+/// ```
+pub struct IntoKeys<K, V, A: Allocator = Global> {
+    inner: IntoIter<K, V, A>,
+}
+
+impl<K, V, A: Allocator> Iterator for IntoKeys<K, V, A> {
+    type Item = K;
+
+    #[inline]
+    fn next(&mut self) -> Option<K> {
+        self.inner.next().map(|(k, _)| k)
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<K, V, A: Allocator> ExactSizeIterator for IntoKeys<K, V, A> {
+    #[inline]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<K, V, A: Allocator> FusedIterator for IntoKeys<K, V, A> {}
+
+impl<K: Debug, V: Debug, A: Allocator> fmt::Debug for IntoKeys<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list()
+            .entries(self.inner.iter().map(|(k, _)| k))
+            .finish()
+    }
+}
+
+/// An owning iterator over the values of a `HashMap` in arbitrary order.
+/// The iterator element type is `V`.
+///
+/// This `struct` is created by the [`into_values`] method on [`HashMap`].
+/// See its documentation for more. The map cannot be used after calling that method.
+///
+/// [`into_values`]: struct.HashMap.html#method.into_values
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut values = map.into_values();
+/// let mut vec = vec![values.next(), values.next(), values.next()];
+///
+/// // The `IntoValues` iterator produces values in arbitrary order, so
+/// // the values must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some("a"), Some("b"), Some("c")]);
+///
+/// // It is fused iterator
+/// assert_eq!(values.next(), None);
+/// assert_eq!(values.next(), None);
+/// ```
+pub struct IntoValues<K, V, A: Allocator = Global> {
+    inner: IntoIter<K, V, A>,
+}
+
+impl<K, V, A: Allocator> Iterator for IntoValues<K, V, A> {
+    type Item = V;
+
+    #[inline]
+    fn next(&mut self) -> Option<V> {
+        self.inner.next().map(|(_, v)| v)
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<K, V, A: Allocator> ExactSizeIterator for IntoValues<K, V, A> {
+    #[inline]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<K, V, A: Allocator> FusedIterator for IntoValues<K, V, A> {}
+
+impl<K, V: Debug, A: Allocator> fmt::Debug for IntoValues<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list()
+            .entries(self.inner.iter().map(|(_, v)| v))
+            .finish()
+    }
+}
+
+/// An iterator over the keys of a `HashMap` in arbitrary order.
+/// The iterator element type is `&'a K`.
+///
+/// This `struct` is created by the [`keys`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`keys`]: struct.HashMap.html#method.keys
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut keys = map.keys();
+/// let mut vec = vec![keys.next(), keys.next(), keys.next()];
+///
+/// // The `Keys` iterator produces keys in arbitrary order, so the
+/// // keys must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some(&1), Some(&2), Some(&3)]);
+///
+/// // It is fused iterator
+/// assert_eq!(keys.next(), None);
+/// assert_eq!(keys.next(), None);
+/// ```
+pub struct Keys<'a, K, V> {
+    inner: Iter<'a, K, V>,
+}
+
+// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
+impl<K, V> Clone for Keys<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Keys {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+impl<K: Debug, V> fmt::Debug for Keys<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+/// An iterator over the values of a `HashMap` in arbitrary order.
+/// The iterator element type is `&'a V`.
+///
+/// This `struct` is created by the [`values`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`values`]: struct.HashMap.html#method.values
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut values = map.values();
+/// let mut vec = vec![values.next(), values.next(), values.next()];
+///
+/// // The `Values` iterator produces values in arbitrary order, so the
+/// // values must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some(&"a"), Some(&"b"), Some(&"c")]);
+///
+/// // It is fused iterator
+/// assert_eq!(values.next(), None);
+/// assert_eq!(values.next(), None);
+/// ```
+pub struct Values<'a, K, V> {
+    inner: Iter<'a, K, V>,
+}
+
+// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
+impl<K, V> Clone for Values<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Values {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+impl<K, V: Debug> fmt::Debug for Values<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+/// A draining iterator over the entries of a `HashMap` in arbitrary
+/// order. The iterator element type is `(K, V)`.
+///
+/// This `struct` is created by the [`drain`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`drain`]: struct.HashMap.html#method.drain
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let mut map: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut drain_iter = map.drain();
+/// let mut vec = vec![drain_iter.next(), drain_iter.next(), drain_iter.next()];
+///
+/// // The `Drain` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some((1, "a")), Some((2, "b")), Some((3, "c"))]);
+///
+/// // It is fused iterator
+/// assert_eq!(drain_iter.next(), None);
+/// assert_eq!(drain_iter.next(), None);
+/// ```
+pub struct Drain<'a, K, V, A: Allocator = Global> {
+    inner: RawDrain<'a, (K, V), A>,
+}
+
+impl<K, V, A: Allocator> Drain<'_, K, V, A> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn iter(&self) -> Iter<'_, K, V> {
+        Iter {
+            inner: self.inner.iter(),
+            marker: PhantomData,
+        }
+    }
+}
+
+/// A draining iterator over entries of a `HashMap` which don't satisfy the predicate
+/// `f(&k, &mut v)` in arbitrary order. The iterator element type is `(K, V)`.
+///
+/// This `struct` is created by the [`extract_if`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`extract_if`]: struct.HashMap.html#method.extract_if
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let mut map: HashMap<i32, &str> = [(1, "a"), (2, "b"), (3, "c")].into();
+///
+/// let mut extract_if = map.extract_if(|k, _v| k % 2 != 0);
+/// let mut vec = vec![extract_if.next(), extract_if.next()];
+///
+/// // The `ExtractIf` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [Some((1, "a")),Some((3, "c"))]);
+///
+/// // It is fused iterator
+/// assert_eq!(extract_if.next(), None);
+/// assert_eq!(extract_if.next(), None);
+/// drop(extract_if);
+///
+/// assert_eq!(map.len(), 1);
+/// ```
+#[must_use = "Iterators are lazy unless consumed"]
+pub struct ExtractIf<'a, K, V, F, A: Allocator = Global>
+where
+    F: FnMut(&K, &mut V) -> bool,
+{
+    f: F,
+    inner: ExtractIfInner<'a, K, V, A>,
+}
+
+impl<K, V, F, A> Iterator for ExtractIf<'_, K, V, F, A>
+where
+    F: FnMut(&K, &mut V) -> bool,
+    A: Allocator,
+{
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next(&mut self.f)
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (0, self.inner.iter.size_hint().1)
+    }
+}
+
+impl<K, V, F> FusedIterator for ExtractIf<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
+
+/// Portions of `ExtractIf` shared with `set::ExtractIf`
+pub(super) struct ExtractIfInner<'a, K, V, A: Allocator> {
+    pub iter: RawIter<(K, V)>,
+    pub table: &'a mut RawTable<(K, V), A>,
+}
+
+impl<K, V, A: Allocator> ExtractIfInner<'_, K, V, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn next<F>(&mut self, f: &mut F) -> Option<(K, V)>
+    where
+        F: FnMut(&K, &mut V) -> bool,
+    {
+        unsafe {
+            for item in &mut self.iter {
+                let &mut (ref key, ref mut value) = item.as_mut();
+                if f(key, value) {
+                    return Some(self.table.remove(item).0);
+                }
+            }
+        }
+        None
+    }
+}
+
+/// A mutable iterator over the values of a `HashMap` in arbitrary order.
+/// The iterator element type is `&'a mut V`.
+///
+/// This `struct` is created by the [`values_mut`] method on [`HashMap`]. See its
+/// documentation for more.
+///
+/// [`values_mut`]: struct.HashMap.html#method.values_mut
+/// [`HashMap`]: struct.HashMap.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashMap;
+///
+/// let mut map: HashMap<_, _> = [(1, "One".to_owned()), (2, "Two".into())].into();
+///
+/// let mut values = map.values_mut();
+/// values.next().map(|v| v.push_str(" Mississippi"));
+/// values.next().map(|v| v.push_str(" Mississippi"));
+///
+/// // It is fused iterator
+/// assert_eq!(values.next(), None);
+/// assert_eq!(values.next(), None);
+///
+/// assert_eq!(map.get(&1).unwrap(), &"One Mississippi".to_owned());
+/// assert_eq!(map.get(&2).unwrap(), &"Two Mississippi".to_owned());
+/// ```
+pub struct ValuesMut<'a, K, V> {
+    inner: IterMut<'a, K, V>,
+}
+
+/// A builder for computing where in a [`HashMap`] a key-value pair would be stored.
+///
+/// See the [`HashMap::raw_entry_mut`] docs for usage examples.
+///
+/// [`HashMap::raw_entry_mut`]: struct.HashMap.html#method.raw_entry_mut
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{RawEntryBuilderMut, RawEntryMut::Vacant, RawEntryMut::Occupied};
+/// use hashbrown::HashMap;
+/// use core::hash::{BuildHasher, Hash};
+///
+/// let mut map = HashMap::new();
+/// map.extend([(1, 11), (2, 12), (3, 13), (4, 14), (5, 15), (6, 16)]);
+/// assert_eq!(map.len(), 6);
+///
+/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+///     use core::hash::Hasher;
+///     let mut state = hash_builder.build_hasher();
+///     key.hash(&mut state);
+///     state.finish()
+/// }
+///
+/// let builder: RawEntryBuilderMut<_, _, _> = map.raw_entry_mut();
+///
+/// // Existing key
+/// match builder.from_key(&6) {
+///     Vacant(_) => unreachable!(),
+///     Occupied(view) => assert_eq!(view.get(), &16),
+/// }
+///
+/// for key in 0..12 {
+///     let hash = compute_hash(map.hasher(), &key);
+///     let value = map.get(&key).cloned();
+///     let key_value = value.as_ref().map(|v| (&key, v));
+///
+///     println!("Key: {} and value: {:?}", key, value);
+///
+///     match map.raw_entry_mut().from_key(&key) {
+///         Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
+///         Vacant(_) => assert_eq!(value, None),
+///     }
+///     match map.raw_entry_mut().from_key_hashed_nocheck(hash, &key) {
+///         Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
+///         Vacant(_) => assert_eq!(value, None),
+///     }
+///     match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
+///         Occupied(mut o) => assert_eq!(Some(o.get_key_value()), key_value),
+///         Vacant(_) => assert_eq!(value, None),
+///     }
+/// }
+///
+/// assert_eq!(map.len(), 6);
+/// ```
+pub struct RawEntryBuilderMut<'a, K, V, S, A: Allocator = Global> {
+    map: &'a mut HashMap<K, V, S, A>,
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied.
+///
+/// This is a lower-level version of [`Entry`].
+///
+/// This `enum` is constructed through the [`raw_entry_mut`] method on [`HashMap`],
+/// then calling one of the methods of that [`RawEntryBuilderMut`].
+///
+/// [`HashMap`]: struct.HashMap.html
+/// [`Entry`]: enum.Entry.html
+/// [`raw_entry_mut`]: struct.HashMap.html#method.raw_entry_mut
+/// [`RawEntryBuilderMut`]: struct.RawEntryBuilderMut.html
+///
+/// # Examples
+///
+/// ```
+/// use core::hash::{BuildHasher, Hash};
+/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};
+///
+/// let mut map = HashMap::new();
+/// map.extend([('a', 1), ('b', 2), ('c', 3)]);
+/// assert_eq!(map.len(), 3);
+///
+/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+///     use core::hash::Hasher;
+///     let mut state = hash_builder.build_hasher();
+///     key.hash(&mut state);
+///     state.finish()
+/// }
+///
+/// // Existing key (insert)
+/// let raw: RawEntryMut<_, _, _> = map.raw_entry_mut().from_key(&'a');
+/// let _raw_o: RawOccupiedEntryMut<_, _, _> = raw.insert('a', 10);
+/// assert_eq!(map.len(), 3);
+///
+/// // Nonexistent key (insert)
+/// map.raw_entry_mut().from_key(&'d').insert('d', 40);
+/// assert_eq!(map.len(), 4);
+///
+/// // Existing key (or_insert)
+/// let hash = compute_hash(map.hasher(), &'b');
+/// let kv = map
+///     .raw_entry_mut()
+///     .from_key_hashed_nocheck(hash, &'b')
+///     .or_insert('b', 20);
+/// assert_eq!(kv, (&mut 'b', &mut 2));
+/// *kv.1 = 20;
+/// assert_eq!(map.len(), 4);
+///
+/// // Nonexistent key (or_insert)
+/// let hash = compute_hash(map.hasher(), &'e');
+/// let kv = map
+///     .raw_entry_mut()
+///     .from_key_hashed_nocheck(hash, &'e')
+///     .or_insert('e', 50);
+/// assert_eq!(kv, (&mut 'e', &mut 50));
+/// assert_eq!(map.len(), 5);
+///
+/// // Existing key (or_insert_with)
+/// let hash = compute_hash(map.hasher(), &'c');
+/// let kv = map
+///     .raw_entry_mut()
+///     .from_hash(hash, |q| q == &'c')
+///     .or_insert_with(|| ('c', 30));
+/// assert_eq!(kv, (&mut 'c', &mut 3));
+/// *kv.1 = 30;
+/// assert_eq!(map.len(), 5);
+///
+/// // Nonexistent key (or_insert_with)
+/// let hash = compute_hash(map.hasher(), &'f');
+/// let kv = map
+///     .raw_entry_mut()
+///     .from_hash(hash, |q| q == &'f')
+///     .or_insert_with(|| ('f', 60));
+/// assert_eq!(kv, (&mut 'f', &mut 60));
+/// assert_eq!(map.len(), 6);
+///
+/// println!("Our HashMap: {:?}", map);
+///
+/// let mut vec: Vec<_> = map.iter().map(|(&k, &v)| (k, v)).collect();
+/// // The `Iter` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [('a', 10), ('b', 20), ('c', 30), ('d', 40), ('e', 50), ('f', 60)]);
+/// ```
+pub enum RawEntryMut<'a, K, V, S, A: Allocator = Global> {
+    /// An occupied entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::{hash_map::RawEntryMut, HashMap};
+    /// let mut map: HashMap<_, _> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => unreachable!(),
+    ///     RawEntryMut::Occupied(_) => { }
+    /// }
+    /// ```
+    Occupied(RawOccupiedEntryMut<'a, K, V, S, A>),
+    /// A vacant entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::{hash_map::RawEntryMut, HashMap};
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
+    ///
+    /// match map.raw_entry_mut().from_key("a") {
+    ///     RawEntryMut::Occupied(_) => unreachable!(),
+    ///     RawEntryMut::Vacant(_) => { }
+    /// }
+    /// ```
+    Vacant(RawVacantEntryMut<'a, K, V, S, A>),
+}
+
+/// A view into an occupied entry in a `HashMap`.
+/// It is part of the [`RawEntryMut`] enum.
+///
+/// [`RawEntryMut`]: enum.RawEntryMut.html
+///
+/// # Examples
+///
+/// ```
+/// use core::hash::{BuildHasher, Hash};
+/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};
+///
+/// let mut map = HashMap::new();
+/// map.extend([("a", 10), ("b", 20), ("c", 30)]);
+///
+/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+///     use core::hash::Hasher;
+///     let mut state = hash_builder.build_hasher();
+///     key.hash(&mut state);
+///     state.finish()
+/// }
+///
+/// let _raw_o: RawOccupiedEntryMut<_, _, _> = map.raw_entry_mut().from_key(&"a").insert("a", 100);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (insert and update)
+/// match map.raw_entry_mut().from_key(&"a") {
+///     RawEntryMut::Vacant(_) => unreachable!(),
+///     RawEntryMut::Occupied(mut view) => {
+///         assert_eq!(view.get(), &100);
+///         let v = view.get_mut();
+///         let new_v = (*v) * 10;
+///         *v = new_v;
+///         assert_eq!(view.insert(1111), 1000);
+///     }
+/// }
+///
+/// assert_eq!(map[&"a"], 1111);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (take)
+/// let hash = compute_hash(map.hasher(), &"c");
+/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
+///     RawEntryMut::Vacant(_) => unreachable!(),
+///     RawEntryMut::Occupied(view) => {
+///         assert_eq!(view.remove_entry(), ("c", 30));
+///     }
+/// }
+/// assert_eq!(map.raw_entry().from_key(&"c"), None);
+/// assert_eq!(map.len(), 2);
+///
+/// let hash = compute_hash(map.hasher(), &"b");
+/// match map.raw_entry_mut().from_hash(hash, |q| *q == "b") {
+///     RawEntryMut::Vacant(_) => unreachable!(),
+///     RawEntryMut::Occupied(view) => {
+///         assert_eq!(view.remove_entry(), ("b", 20));
+///     }
+/// }
+/// assert_eq!(map.get(&"b"), None);
+/// assert_eq!(map.len(), 1);
+/// ```
+pub struct RawOccupiedEntryMut<'a, K, V, S, A: Allocator = Global> {
+    elem: Bucket<(K, V)>,
+    table: &'a mut RawTable<(K, V), A>,
+    hash_builder: &'a S,
+}
+
+unsafe impl<K, V, S, A> Send for RawOccupiedEntryMut<'_, K, V, S, A>
+where
+    K: Send,
+    V: Send,
+    S: Send,
+    A: Send + Allocator,
+{
+}
+unsafe impl<K, V, S, A> Sync for RawOccupiedEntryMut<'_, K, V, S, A>
+where
+    K: Sync,
+    V: Sync,
+    S: Sync,
+    A: Sync + Allocator,
+{
+}
+
+/// A view into a vacant entry in a `HashMap`.
+/// It is part of the [`RawEntryMut`] enum.
+///
+/// [`RawEntryMut`]: enum.RawEntryMut.html
+///
+/// # Examples
+///
+/// ```
+/// use core::hash::{BuildHasher, Hash};
+/// use hashbrown::hash_map::{HashMap, RawEntryMut, RawVacantEntryMut};
+///
+/// let mut map = HashMap::<&str, i32>::new();
+///
+/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+///     use core::hash::Hasher;
+///     let mut state = hash_builder.build_hasher();
+///     key.hash(&mut state);
+///     state.finish()
+/// }
+///
+/// let raw_v: RawVacantEntryMut<_, _, _> = match map.raw_entry_mut().from_key(&"a") {
+///     RawEntryMut::Vacant(view) => view,
+///     RawEntryMut::Occupied(_) => unreachable!(),
+/// };
+/// raw_v.insert("a", 10);
+/// assert!(map[&"a"] == 10 && map.len() == 1);
+///
+/// // Nonexistent key (insert and update)
+/// let hash = compute_hash(map.hasher(), &"b");
+/// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"b") {
+///     RawEntryMut::Occupied(_) => unreachable!(),
+///     RawEntryMut::Vacant(view) => {
+///         let (k, value) = view.insert("b", 2);
+///         assert_eq!((*k, *value), ("b", 2));
+///         *value = 20;
+///     }
+/// }
+/// assert!(map[&"b"] == 20 && map.len() == 2);
+///
+/// let hash = compute_hash(map.hasher(), &"c");
+/// match map.raw_entry_mut().from_hash(hash, |q| *q == "c") {
+///     RawEntryMut::Occupied(_) => unreachable!(),
+///     RawEntryMut::Vacant(view) => {
+///         assert_eq!(view.insert("c", 30), (&mut "c", &mut 30));
+///     }
+/// }
+/// assert!(map[&"c"] == 30 && map.len() == 3);
+/// ```
+pub struct RawVacantEntryMut<'a, K, V, S, A: Allocator = Global> {
+    table: &'a mut RawTable<(K, V), A>,
+    hash_builder: &'a S,
+}
+
+/// A builder for computing where in a [`HashMap`] a key-value pair would be stored.
+///
+/// See the [`HashMap::raw_entry`] docs for usage examples.
+///
+/// [`HashMap::raw_entry`]: struct.HashMap.html#method.raw_entry
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{HashMap, RawEntryBuilder};
+/// use core::hash::{BuildHasher, Hash};
+///
+/// let mut map = HashMap::new();
+/// map.extend([(1, 10), (2, 20), (3, 30)]);
+///
+/// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+///     use core::hash::Hasher;
+///     let mut state = hash_builder.build_hasher();
+///     key.hash(&mut state);
+///     state.finish()
+/// }
+///
+/// for k in 0..6 {
+///     let hash = compute_hash(map.hasher(), &k);
+///     let v = map.get(&k).cloned();
+///     let kv = v.as_ref().map(|v| (&k, v));
+///
+///     println!("Key: {} and value: {:?}", k, v);
+///     let builder: RawEntryBuilder<_, _, _> = map.raw_entry();
+///     assert_eq!(builder.from_key(&k), kv);
+///     assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
+///     assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
+/// }
+/// ```
+pub struct RawEntryBuilder<'a, K, V, S, A: Allocator = Global> {
+    map: &'a HashMap<K, V, S, A>,
+}
+
+impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A> {
+    /// Creates a `RawEntryMut` from the given key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let key = "a";
+    /// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key(&key);
+    /// entry.insert(key, 100);
+    /// assert_eq!(map[&"a"], 100);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_key<Q: ?Sized>(self, k: &Q) -> RawEntryMut<'a, K, V, S, A>
+    where
+        S: BuildHasher,
+        Q: Hash + Equivalent<K>,
+    {
+        let hash = make_hash::<Q, S>(&self.map.hash_builder, k);
+        self.from_key_hashed_nocheck(hash, k)
+    }
+
+    /// Creates a `RawEntryMut` from the given key and its hash.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let key = "a";
+    /// let hash = compute_hash(map.hasher(), &key);
+    /// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_key_hashed_nocheck(hash, &key);
+    /// entry.insert(key, 100);
+    /// assert_eq!(map[&"a"], 100);
+    /// ```
+    #[inline]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> RawEntryMut<'a, K, V, S, A>
+    where
+        Q: Equivalent<K>,
+    {
+        self.from_hash(hash, equivalent(k))
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> RawEntryBuilderMut<'a, K, V, S, A> {
+    /// Creates a `RawEntryMut` from the given hash and matching function.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let key = "a";
+    /// let hash = compute_hash(map.hasher(), &key);
+    /// let entry: RawEntryMut<&str, u32, _> = map.raw_entry_mut().from_hash(hash, |k| k == &key);
+    /// entry.insert(key, 100);
+    /// assert_eq!(map[&"a"], 100);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_hash<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S, A>
+    where
+        for<'b> F: FnMut(&'b K) -> bool,
+    {
+        self.search(hash, is_match)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn search<F>(self, hash: u64, mut is_match: F) -> RawEntryMut<'a, K, V, S, A>
+    where
+        for<'b> F: FnMut(&'b K) -> bool,
+    {
+        match self.map.table.find(hash, |(k, _)| is_match(k)) {
+            Some(elem) => RawEntryMut::Occupied(RawOccupiedEntryMut {
+                elem,
+                table: &mut self.map.table,
+                hash_builder: &self.map.hash_builder,
+            }),
+            None => RawEntryMut::Vacant(RawVacantEntryMut {
+                table: &mut self.map.table,
+                hash_builder: &self.map.hash_builder,
+            }),
+        }
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> RawEntryBuilder<'a, K, V, S, A> {
+    /// Access an immutable entry by key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    /// let key = "a";
+    /// assert_eq!(map.raw_entry().from_key(&key), Some((&"a", &100)));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_key<Q: ?Sized>(self, k: &Q) -> Option<(&'a K, &'a V)>
+    where
+        S: BuildHasher,
+        Q: Hash + Equivalent<K>,
+    {
+        let hash = make_hash::<Q, S>(&self.map.hash_builder, k);
+        self.from_key_hashed_nocheck(hash, k)
+    }
+
+    /// Access an immutable entry by a key and its hash.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::HashMap;
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    /// let key = "a";
+    /// let hash = compute_hash(map.hasher(), &key);
+    /// assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &key), Some((&"a", &100)));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> Option<(&'a K, &'a V)>
+    where
+        Q: Equivalent<K>,
+    {
+        self.from_hash(hash, equivalent(k))
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn search<F>(self, hash: u64, mut is_match: F) -> Option<(&'a K, &'a V)>
+    where
+        F: FnMut(&K) -> bool,
+    {
+        match self.map.table.get(hash, |(k, _)| is_match(k)) {
+            Some((key, value)) => Some((key, value)),
+            None => None,
+        }
+    }
+
+    /// Access an immutable entry by hash and matching function.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::HashMap;
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    /// let key = "a";
+    /// let hash = compute_hash(map.hasher(), &key);
+    /// assert_eq!(map.raw_entry().from_hash(hash, |k| k == &key), Some((&"a", &100)));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)>
+    where
+        F: FnMut(&K) -> bool,
+    {
+        self.search(hash, is_match)
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> RawEntryMut<'a, K, V, S, A> {
+    /// Sets the value of the entry, and returns a RawOccupiedEntryMut.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let entry = map.raw_entry_mut().from_key("horseyland").insert("horseyland", 37);
+    ///
+    /// assert_eq!(entry.remove_entry(), ("horseyland", 37));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S, A>
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            RawEntryMut::Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+            RawEntryMut::Vacant(entry) => entry.insert_entry(key, value),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the default if empty, and returns
+    /// mutable references to the key and value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// *map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 10).1 *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self, default_key: K, default_val: V) -> (&'a mut K, &'a mut V)
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            RawEntryMut::Occupied(entry) => entry.into_key_value(),
+            RawEntryMut::Vacant(entry) => entry.insert(default_key, default_val),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the default function if empty,
+    /// and returns mutable references to the key and value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, String> = HashMap::new();
+    ///
+    /// map.raw_entry_mut().from_key("poneyland").or_insert_with(|| {
+    ///     ("poneyland", "hoho".to_string())
+    /// });
+    ///
+    /// assert_eq!(map["poneyland"], "hoho".to_string());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with<F>(self, default: F) -> (&'a mut K, &'a mut V)
+    where
+        F: FnOnce() -> (K, V),
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            RawEntryMut::Occupied(entry) => entry.into_key_value(),
+            RawEntryMut::Vacant(entry) => {
+                let (k, v) = default();
+                entry.insert(k, v)
+            }
+        }
+    }
+
+    /// Provides in-place mutable access to an occupied entry before any
+    /// potential inserts into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.raw_entry_mut()
+    ///    .from_key("poneyland")
+    ///    .and_modify(|_k, v| { *v += 1 })
+    ///    .or_insert("poneyland", 42);
+    /// assert_eq!(map["poneyland"], 42);
+    ///
+    /// map.raw_entry_mut()
+    ///    .from_key("poneyland")
+    ///    .and_modify(|_k, v| { *v += 1 })
+    ///    .or_insert("poneyland", 0);
+    /// assert_eq!(map["poneyland"], 43);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_modify<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&mut K, &mut V),
+    {
+        match self {
+            RawEntryMut::Occupied(mut entry) => {
+                {
+                    let (k, v) = entry.get_key_value_mut();
+                    f(k, v);
+                }
+                RawEntryMut::Occupied(entry)
+            }
+            RawEntryMut::Vacant(entry) => RawEntryMut::Vacant(entry),
+        }
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// an occupied entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RawEntryMut;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// let entry = map
+    ///     .raw_entry_mut()
+    ///     .from_key("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| panic!());
+    ///
+    /// match entry {
+    ///     RawEntryMut::Vacant(_) => {},
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// map.insert("poneyland", 42);
+    ///
+    /// let entry = map
+    ///     .raw_entry_mut()
+    ///     .from_key("poneyland")
+    ///     .and_replace_entry_with(|k, v| {
+    ///         assert_eq!(k, &"poneyland");
+    ///         assert_eq!(v, 42);
+    ///         Some(v + 1)
+    ///     });
+    ///
+    /// match entry {
+    ///     RawEntryMut::Occupied(e) => {
+    ///         assert_eq!(e.key(), &"poneyland");
+    ///         assert_eq!(e.get(), &43);
+    ///     },
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 43);
+    ///
+    /// let entry = map
+    ///     .raw_entry_mut()
+    ///     .from_key("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| None);
+    ///
+    /// match entry {
+    ///     RawEntryMut::Vacant(_) => {},
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// assert!(!map.contains_key("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_replace_entry_with<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        match self {
+            RawEntryMut::Occupied(entry) => entry.replace_entry_with(f),
+            RawEntryMut::Vacant(_) => self,
+        }
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> RawOccupiedEntryMut<'a, K, V, S, A> {
+    /// Gets a reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => assert_eq!(o.key(), &"a")
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
+    }
+
+    /// Gets a mutable reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    /// use std::rc::Rc;
+    ///
+    /// let key_one = Rc::new("a");
+    /// let key_two = Rc::new("a");
+    ///
+    /// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
+    /// map.insert(key_one.clone(), 10);
+    ///
+    /// assert_eq!(map[&key_one], 10);
+    /// assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    /// match map.raw_entry_mut().from_key(&key_one) {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(mut o) => {
+    ///         *o.key_mut() = key_two.clone();
+    ///     }
+    /// }
+    /// assert_eq!(map[&key_two], 10);
+    /// assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key_mut(&mut self) -> &mut K {
+        unsafe { &mut self.elem.as_mut().0 }
+    }
+
+    /// Converts the entry into a mutable reference to the key in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    /// use std::rc::Rc;
+    ///
+    /// let key_one = Rc::new("a");
+    /// let key_two = Rc::new("a");
+    ///
+    /// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
+    /// map.insert(key_one.clone(), 10);
+    ///
+    /// assert_eq!(map[&key_one], 10);
+    /// assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    /// let inside_key: &mut Rc<&str>;
+    ///
+    /// match map.raw_entry_mut().from_key(&key_one) {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => inside_key = o.into_key(),
+    /// }
+    /// *inside_key = key_two.clone();
+    ///
+    /// assert_eq!(map[&key_two], 10);
+    /// assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key(self) -> &'a mut K {
+        unsafe { &mut self.elem.as_mut().0 }
+    }
+
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => assert_eq!(o.get(), &100),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &V {
+        unsafe { &self.elem.as_ref().1 }
+    }
+
+    /// Converts the OccupiedEntry into a mutable reference to the value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// let value: &mut u32;
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => value = o.into_mut(),
+    /// }
+    /// *value += 900;
+    ///
+    /// assert_eq!(map[&"a"], 1000);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(mut o) => *o.get_mut() += 900,
+    /// }
+    ///
+    /// assert_eq!(map[&"a"], 1000);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Gets a reference to the key and value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => assert_eq!(o.get_key_value(), (&"a", &100)),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_key_value(&self) -> (&K, &V) {
+        unsafe {
+            let (key, value) = self.elem.as_ref();
+            (key, value)
+        }
+    }
+
+    /// Gets a mutable reference to the key and value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    /// use std::rc::Rc;
+    ///
+    /// let key_one = Rc::new("a");
+    /// let key_two = Rc::new("a");
+    ///
+    /// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
+    /// map.insert(key_one.clone(), 10);
+    ///
+    /// assert_eq!(map[&key_one], 10);
+    /// assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    /// match map.raw_entry_mut().from_key(&key_one) {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(mut o) => {
+    ///         let (inside_key, inside_value) = o.get_key_value_mut();
+    ///         *inside_key = key_two.clone();
+    ///         *inside_value = 100;
+    ///     }
+    /// }
+    /// assert_eq!(map[&key_two], 100);
+    /// assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_key_value_mut(&mut self) -> (&mut K, &mut V) {
+        unsafe {
+            let &mut (ref mut key, ref mut value) = self.elem.as_mut();
+            (key, value)
+        }
+    }
+
+    /// Converts the OccupiedEntry into a mutable reference to the key and value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    /// use std::rc::Rc;
+    ///
+    /// let key_one = Rc::new("a");
+    /// let key_two = Rc::new("a");
+    ///
+    /// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
+    /// map.insert(key_one.clone(), 10);
+    ///
+    /// assert_eq!(map[&key_one], 10);
+    /// assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    /// let inside_key: &mut Rc<&str>;
+    /// let inside_value: &mut u32;
+    /// match map.raw_entry_mut().from_key(&key_one) {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => {
+    ///         let tuple = o.into_key_value();
+    ///         inside_key = tuple.0;
+    ///         inside_value = tuple.1;
+    ///     }
+    /// }
+    /// *inside_key = key_two.clone();
+    /// *inside_value = 100;
+    /// assert_eq!(map[&key_two], 100);
+    /// assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key_value(self) -> (&'a mut K, &'a mut V) {
+        unsafe {
+            let &mut (ref mut key, ref mut value) = self.elem.as_mut();
+            (key, value)
+        }
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(mut o) => assert_eq!(o.insert(1000), 100),
+    /// }
+    ///
+    /// assert_eq!(map[&"a"], 1000);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    /// use std::rc::Rc;
+    ///
+    /// let key_one = Rc::new("a");
+    /// let key_two = Rc::new("a");
+    ///
+    /// let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
+    /// map.insert(key_one.clone(), 10);
+    ///
+    /// assert_eq!(map[&key_one], 10);
+    /// assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    /// match map.raw_entry_mut().from_key(&key_one) {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(mut o) => {
+    ///         let old_key = o.insert_key(key_two.clone());
+    ///         assert!(Rc::ptr_eq(&old_key, &key_one));
+    ///     }
+    /// }
+    /// assert_eq!(map[&key_two], 10);
+    /// assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_key(&mut self, key: K) -> K {
+        mem::replace(self.key_mut(), key)
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => assert_eq!(o.remove(), 100),
+    /// }
+    /// assert_eq!(map.get(&"a"), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> V {
+        self.remove_entry().1
+    }
+
+    /// Take the ownership of the key and value from the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => assert_eq!(o.remove_entry(), ("a", 100)),
+    /// }
+    /// assert_eq!(map.get(&"a"), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(self) -> (K, V) {
+        unsafe { self.table.remove(self.elem).0 }
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// the entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// let raw_entry = match map.raw_entry_mut().from_key(&"a") {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => o.replace_entry_with(|k, v| {
+    ///         assert_eq!(k, &"a");
+    ///         assert_eq!(v, 100);
+    ///         Some(v + 900)
+    ///     }),
+    /// };
+    /// let raw_entry = match raw_entry {
+    ///     RawEntryMut::Vacant(_) => panic!(),
+    ///     RawEntryMut::Occupied(o) => o.replace_entry_with(|k, v| {
+    ///         assert_eq!(k, &"a");
+    ///         assert_eq!(v, 1000);
+    ///         None
+    ///     }),
+    /// };
+    /// match raw_entry {
+    ///     RawEntryMut::Vacant(_) => { },
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    /// };
+    /// assert_eq!(map.get(&"a"), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry_with<F>(self, f: F) -> RawEntryMut<'a, K, V, S, A>
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        unsafe {
+            let still_occupied = self
+                .table
+                .replace_bucket_with(self.elem.clone(), |(key, value)| {
+                    f(&key, value).map(|new_value| (key, new_value))
+                });
+
+            if still_occupied {
+                RawEntryMut::Occupied(self)
+            } else {
+                RawEntryMut::Vacant(RawVacantEntryMut {
+                    table: self.table,
+                    hash_builder: self.hash_builder,
+                })
+            }
+        }
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> RawVacantEntryMut<'a, K, V, S, A> {
+    /// Sets the value of the entry with the VacantEntry's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.raw_entry_mut().from_key(&"c") {
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    ///     RawEntryMut::Vacant(v) => assert_eq!(v.insert("c", 300), (&mut "c", &mut 300)),
+    /// }
+    ///
+    /// assert_eq!(map[&"c"], 300);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, key: K, value: V) -> (&'a mut K, &'a mut V)
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        let hash = make_hash::<K, S>(self.hash_builder, &key);
+        self.insert_hashed_nocheck(hash, key, value)
+    }
+
+    /// Sets the value of the entry with the VacantEntry's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();
+    /// let key = "c";
+    /// let hash = compute_hash(map.hasher(), &key);
+    ///
+    /// match map.raw_entry_mut().from_key_hashed_nocheck(hash, &key) {
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    ///     RawEntryMut::Vacant(v) => assert_eq!(
+    ///         v.insert_hashed_nocheck(hash, key, 300),
+    ///         (&mut "c", &mut 300)
+    ///     ),
+    /// }
+    ///
+    /// assert_eq!(map[&"c"], 300);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::shadow_unrelated)]
+    pub fn insert_hashed_nocheck(self, hash: u64, key: K, value: V) -> (&'a mut K, &'a mut V)
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        let &mut (ref mut k, ref mut v) = self.table.insert_entry(
+            hash,
+            (key, value),
+            make_hasher::<_, V, S>(self.hash_builder),
+        );
+        (k, v)
+    }
+
+    /// Set the value of an entry with a custom hasher function.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::hash_map::{HashMap, RawEntryMut};
+    ///
+    /// fn make_hasher<K, S>(hash_builder: &S) -> impl Fn(&K) -> u64 + '_
+    /// where
+    ///     K: Hash + ?Sized,
+    ///     S: BuildHasher,
+    /// {
+    ///     move |key: &K| {
+    ///         use core::hash::Hasher;
+    ///         let mut state = hash_builder.build_hasher();
+    ///         key.hash(&mut state);
+    ///         state.finish()
+    ///     }
+    /// }
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let key = "a";
+    /// let hash_builder = map.hasher().clone();
+    /// let hash = make_hasher(&hash_builder)(&key);
+    ///
+    /// match map.raw_entry_mut().from_hash(hash, |q| q == &key) {
+    ///     RawEntryMut::Occupied(_) => panic!(),
+    ///     RawEntryMut::Vacant(v) => assert_eq!(
+    ///         v.insert_with_hasher(hash, key, 100, make_hasher(&hash_builder)),
+    ///         (&mut "a", &mut 100)
+    ///     ),
+    /// }
+    /// map.extend([("b", 200), ("c", 300), ("d", 400), ("e", 500), ("f", 600)]);
+    /// assert_eq!(map[&"a"], 100);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_with_hasher<H>(
+        self,
+        hash: u64,
+        key: K,
+        value: V,
+        hasher: H,
+    ) -> (&'a mut K, &'a mut V)
+    where
+        H: Fn(&K) -> u64,
+    {
+        let &mut (ref mut k, ref mut v) = self
+            .table
+            .insert_entry(hash, (key, value), |x| hasher(&x.0));
+        (k, v)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn insert_entry(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S, A>
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        let hash = make_hash::<K, S>(self.hash_builder, &key);
+        let elem = self.table.insert(
+            hash,
+            (key, value),
+            make_hasher::<_, V, S>(self.hash_builder),
+        );
+        RawOccupiedEntryMut {
+            elem,
+            table: self.table,
+            hash_builder: self.hash_builder,
+        }
+    }
+}
+
+impl<K, V, S, A: Allocator> Debug for RawEntryBuilderMut<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RawEntryBuilder").finish()
+    }
+}
+
+impl<K: Debug, V: Debug, S, A: Allocator> Debug for RawEntryMut<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            RawEntryMut::Vacant(ref v) => f.debug_tuple("RawEntry").field(v).finish(),
+            RawEntryMut::Occupied(ref o) => f.debug_tuple("RawEntry").field(o).finish(),
+        }
+    }
+}
+
+impl<K: Debug, V: Debug, S, A: Allocator> Debug for RawOccupiedEntryMut<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RawOccupiedEntryMut")
+            .field("key", self.key())
+            .field("value", self.get())
+            .finish()
+    }
+}
+
+impl<K, V, S, A: Allocator> Debug for RawVacantEntryMut<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RawVacantEntryMut").finish()
+    }
+}
+
+impl<K, V, S, A: Allocator> Debug for RawEntryBuilder<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RawEntryBuilder").finish()
+    }
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied.
+///
+/// This `enum` is constructed from the [`entry`] method on [`HashMap`].
+///
+/// [`HashMap`]: struct.HashMap.html
+/// [`entry`]: struct.HashMap.html#method.entry
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};
+///
+/// let mut map = HashMap::new();
+/// map.extend([("a", 10), ("b", 20), ("c", 30)]);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (insert)
+/// let entry: Entry<_, _, _> = map.entry("a");
+/// let _raw_o: OccupiedEntry<_, _, _> = entry.insert(1);
+/// assert_eq!(map.len(), 3);
+/// // Nonexistent key (insert)
+/// map.entry("d").insert(4);
+///
+/// // Existing key (or_insert)
+/// let v = map.entry("b").or_insert(2);
+/// assert_eq!(std::mem::replace(v, 2), 20);
+/// // Nonexistent key (or_insert)
+/// map.entry("e").or_insert(5);
+///
+/// // Existing key (or_insert_with)
+/// let v = map.entry("c").or_insert_with(|| 3);
+/// assert_eq!(std::mem::replace(v, 3), 30);
+/// // Nonexistent key (or_insert_with)
+/// map.entry("f").or_insert_with(|| 6);
+///
+/// println!("Our HashMap: {:?}", map);
+///
+/// let mut vec: Vec<_> = map.iter().map(|(&k, &v)| (k, v)).collect();
+/// // The `Iter` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3), ("d", 4), ("e", 5), ("f", 6)]);
+/// ```
+pub enum Entry<'a, K, V, S, A = Global>
+where
+    A: Allocator,
+{
+    /// An occupied entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    /// let mut map: HashMap<_, _> = [("a", 100), ("b", 200)].into();
+    ///
+    /// match map.entry("a") {
+    ///     Entry::Vacant(_) => unreachable!(),
+    ///     Entry::Occupied(_) => { }
+    /// }
+    /// ```
+    Occupied(OccupiedEntry<'a, K, V, S, A>),
+
+    /// A vacant entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    /// let mut map: HashMap<&str, i32> = HashMap::new();
+    ///
+    /// match map.entry("a") {
+    ///     Entry::Occupied(_) => unreachable!(),
+    ///     Entry::Vacant(_) => { }
+    /// }
+    /// ```
+    Vacant(VacantEntry<'a, K, V, S, A>),
+}
+
+impl<K: Debug, V: Debug, S, A: Allocator> Debug for Entry<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Entry::Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(),
+            Entry::Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(),
+        }
+    }
+}
+
+/// A view into an occupied entry in a `HashMap`.
+/// It is part of the [`Entry`] enum.
+///
+/// [`Entry`]: enum.Entry.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};
+///
+/// let mut map = HashMap::new();
+/// map.extend([("a", 10), ("b", 20), ("c", 30)]);
+///
+/// let _entry_o: OccupiedEntry<_, _, _> = map.entry("a").insert(100);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (insert and update)
+/// match map.entry("a") {
+///     Entry::Vacant(_) => unreachable!(),
+///     Entry::Occupied(mut view) => {
+///         assert_eq!(view.get(), &100);
+///         let v = view.get_mut();
+///         *v *= 10;
+///         assert_eq!(view.insert(1111), 1000);
+///     }
+/// }
+///
+/// assert_eq!(map[&"a"], 1111);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (take)
+/// match map.entry("c") {
+///     Entry::Vacant(_) => unreachable!(),
+///     Entry::Occupied(view) => {
+///         assert_eq!(view.remove_entry(), ("c", 30));
+///     }
+/// }
+/// assert_eq!(map.get(&"c"), None);
+/// assert_eq!(map.len(), 2);
+/// ```
+pub struct OccupiedEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> {
+    hash: u64,
+    key: Option<K>,
+    elem: Bucket<(K, V)>,
+    table: &'a mut HashMap<K, V, S, A>,
+}
+
+unsafe impl<K, V, S, A> Send for OccupiedEntry<'_, K, V, S, A>
+where
+    K: Send,
+    V: Send,
+    S: Send,
+    A: Send + Allocator,
+{
+}
+unsafe impl<K, V, S, A> Sync for OccupiedEntry<'_, K, V, S, A>
+where
+    K: Sync,
+    V: Sync,
+    S: Sync,
+    A: Sync + Allocator,
+{
+}
+
+impl<K: Debug, V: Debug, S, A: Allocator> Debug for OccupiedEntry<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedEntry")
+            .field("key", self.key())
+            .field("value", self.get())
+            .finish()
+    }
+}
+
+/// A view into a vacant entry in a `HashMap`.
+/// It is part of the [`Entry`] enum.
+///
+/// [`Entry`]: enum.Entry.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{Entry, HashMap, VacantEntry};
+///
+/// let mut map = HashMap::<&str, i32>::new();
+///
+/// let entry_v: VacantEntry<_, _, _> = match map.entry("a") {
+///     Entry::Vacant(view) => view,
+///     Entry::Occupied(_) => unreachable!(),
+/// };
+/// entry_v.insert(10);
+/// assert!(map[&"a"] == 10 && map.len() == 1);
+///
+/// // Nonexistent key (insert and update)
+/// match map.entry("b") {
+///     Entry::Occupied(_) => unreachable!(),
+///     Entry::Vacant(view) => {
+///         let value = view.insert(2);
+///         assert_eq!(*value, 2);
+///         *value = 20;
+///     }
+/// }
+/// assert!(map[&"b"] == 20 && map.len() == 2);
+/// ```
+pub struct VacantEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> {
+    hash: u64,
+    key: K,
+    table: &'a mut HashMap<K, V, S, A>,
+}
+
+impl<K: Debug, V, S, A: Allocator> Debug for VacantEntry<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VacantEntry").field(self.key()).finish()
+    }
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied,
+/// with any borrowed form of the map's key type.
+///
+///
+/// This `enum` is constructed from the [`entry_ref`] method on [`HashMap`].
+///
+/// [`Hash`] and [`Eq`] on the borrowed form of the map's key type *must* match those
+/// for the key type. It also require that key may be constructed from the borrowed
+/// form through the [`From`] trait.
+///
+/// [`HashMap`]: struct.HashMap.html
+/// [`entry_ref`]: struct.HashMap.html#method.entry_ref
+/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+/// [`From`]: https://doc.rust-lang.org/std/convert/trait.From.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{EntryRef, HashMap, OccupiedEntryRef};
+///
+/// let mut map = HashMap::new();
+/// map.extend([("a".to_owned(), 10), ("b".into(), 20), ("c".into(), 30)]);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (insert)
+/// let key = String::from("a");
+/// let entry: EntryRef<_, _, _, _> = map.entry_ref(&key);
+/// let _raw_o: OccupiedEntryRef<_, _, _, _> = entry.insert(1);
+/// assert_eq!(map.len(), 3);
+/// // Nonexistent key (insert)
+/// map.entry_ref("d").insert(4);
+///
+/// // Existing key (or_insert)
+/// let v = map.entry_ref("b").or_insert(2);
+/// assert_eq!(std::mem::replace(v, 2), 20);
+/// // Nonexistent key (or_insert)
+/// map.entry_ref("e").or_insert(5);
+///
+/// // Existing key (or_insert_with)
+/// let v = map.entry_ref("c").or_insert_with(|| 3);
+/// assert_eq!(std::mem::replace(v, 3), 30);
+/// // Nonexistent key (or_insert_with)
+/// map.entry_ref("f").or_insert_with(|| 6);
+///
+/// println!("Our HashMap: {:?}", map);
+///
+/// for (key, value) in ["a", "b", "c", "d", "e", "f"].into_iter().zip(1..=6) {
+///     assert_eq!(map[key], value)
+/// }
+/// assert_eq!(map.len(), 6);
+/// ```
+pub enum EntryRef<'a, 'b, K, Q: ?Sized, V, S, A = Global>
+where
+    A: Allocator,
+{
+    /// An occupied entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    /// let mut map: HashMap<_, _> = [("a".to_owned(), 100), ("b".into(), 200)].into();
+    ///
+    /// match map.entry_ref("a") {
+    ///     EntryRef::Vacant(_) => unreachable!(),
+    ///     EntryRef::Occupied(_) => { }
+    /// }
+    /// ```
+    Occupied(OccupiedEntryRef<'a, 'b, K, Q, V, S, A>),
+
+    /// A vacant entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    /// let mut map: HashMap<String, i32> = HashMap::new();
+    ///
+    /// match map.entry_ref("a") {
+    ///     EntryRef::Occupied(_) => unreachable!(),
+    ///     EntryRef::Vacant(_) => { }
+    /// }
+    /// ```
+    Vacant(VacantEntryRef<'a, 'b, K, Q, V, S, A>),
+}
+
+impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator> Debug
+    for EntryRef<'_, '_, K, Q, V, S, A>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            EntryRef::Vacant(ref v) => f.debug_tuple("EntryRef").field(v).finish(),
+            EntryRef::Occupied(ref o) => f.debug_tuple("EntryRef").field(o).finish(),
+        }
+    }
+}
+
+enum KeyOrRef<'a, K, Q: ?Sized> {
+    Borrowed(&'a Q),
+    Owned(K),
+}
+
+impl<'a, K, Q: ?Sized> KeyOrRef<'a, K, Q> {
+    fn into_owned(self) -> K
+    where
+        K: From<&'a Q>,
+    {
+        match self {
+            Self::Borrowed(borrowed) => borrowed.into(),
+            Self::Owned(owned) => owned,
+        }
+    }
+}
+
+impl<'a, K: Borrow<Q>, Q: ?Sized> AsRef<Q> for KeyOrRef<'a, K, Q> {
+    fn as_ref(&self) -> &Q {
+        match self {
+            Self::Borrowed(borrowed) => borrowed,
+            Self::Owned(owned) => owned.borrow(),
+        }
+    }
+}
+
+/// A view into an occupied entry in a `HashMap`.
+/// It is part of the [`EntryRef`] enum.
+///
+/// [`EntryRef`]: enum.EntryRef.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{EntryRef, HashMap, OccupiedEntryRef};
+///
+/// let mut map = HashMap::new();
+/// map.extend([("a".to_owned(), 10), ("b".into(), 20), ("c".into(), 30)]);
+///
+/// let key = String::from("a");
+/// let _entry_o: OccupiedEntryRef<_, _, _, _> = map.entry_ref(&key).insert(100);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (insert and update)
+/// match map.entry_ref("a") {
+///     EntryRef::Vacant(_) => unreachable!(),
+///     EntryRef::Occupied(mut view) => {
+///         assert_eq!(view.get(), &100);
+///         let v = view.get_mut();
+///         *v *= 10;
+///         assert_eq!(view.insert(1111), 1000);
+///     }
+/// }
+///
+/// assert_eq!(map["a"], 1111);
+/// assert_eq!(map.len(), 3);
+///
+/// // Existing key (take)
+/// match map.entry_ref("c") {
+///     EntryRef::Vacant(_) => unreachable!(),
+///     EntryRef::Occupied(view) => {
+///         assert_eq!(view.remove_entry(), ("c".to_owned(), 30));
+///     }
+/// }
+/// assert_eq!(map.get("c"), None);
+/// assert_eq!(map.len(), 2);
+/// ```
+pub struct OccupiedEntryRef<'a, 'b, K, Q: ?Sized, V, S, A: Allocator = Global> {
+    hash: u64,
+    key: Option<KeyOrRef<'b, K, Q>>,
+    elem: Bucket<(K, V)>,
+    table: &'a mut HashMap<K, V, S, A>,
+}
+
+unsafe impl<'a, 'b, K, Q, V, S, A> Send for OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
+where
+    K: Send,
+    Q: Sync + ?Sized,
+    V: Send,
+    S: Send,
+    A: Send + Allocator,
+{
+}
+unsafe impl<'a, 'b, K, Q, V, S, A> Sync for OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
+where
+    K: Sync,
+    Q: Sync + ?Sized,
+    V: Sync,
+    S: Sync,
+    A: Sync + Allocator,
+{
+}
+
+impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator> Debug
+    for OccupiedEntryRef<'_, '_, K, Q, V, S, A>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedEntryRef")
+            .field("key", &self.key().borrow())
+            .field("value", &self.get())
+            .finish()
+    }
+}
+
+/// A view into a vacant entry in a `HashMap`.
+/// It is part of the [`EntryRef`] enum.
+///
+/// [`EntryRef`]: enum.EntryRef.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{EntryRef, HashMap, VacantEntryRef};
+///
+/// let mut map = HashMap::<String, i32>::new();
+///
+/// let entry_v: VacantEntryRef<_, _, _, _> = match map.entry_ref("a") {
+///     EntryRef::Vacant(view) => view,
+///     EntryRef::Occupied(_) => unreachable!(),
+/// };
+/// entry_v.insert(10);
+/// assert!(map["a"] == 10 && map.len() == 1);
+///
+/// // Nonexistent key (insert and update)
+/// match map.entry_ref("b") {
+///     EntryRef::Occupied(_) => unreachable!(),
+///     EntryRef::Vacant(view) => {
+///         let value = view.insert(2);
+///         assert_eq!(*value, 2);
+///         *value = 20;
+///     }
+/// }
+/// assert!(map["b"] == 20 && map.len() == 2);
+/// ```
+pub struct VacantEntryRef<'a, 'b, K, Q: ?Sized, V, S, A: Allocator = Global> {
+    hash: u64,
+    key: KeyOrRef<'b, K, Q>,
+    table: &'a mut HashMap<K, V, S, A>,
+}
+
+impl<K: Borrow<Q>, Q: ?Sized + Debug, V, S, A: Allocator> Debug
+    for VacantEntryRef<'_, '_, K, Q, V, S, A>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VacantEntryRef").field(&self.key()).finish()
+    }
+}
+
+/// The error returned by [`try_insert`](HashMap::try_insert) when the key already exists.
+///
+/// Contains the occupied entry, and the value that was not inserted.
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_map::{HashMap, OccupiedError};
+///
+/// let mut map: HashMap<_, _> = [("a", 10), ("b", 20)].into();
+///
+/// // try_insert method returns mutable reference to the value if keys are vacant,
+/// // but if the map did have key present, nothing is updated, and the provided
+/// // value is returned inside `Err(_)` variant
+/// match map.try_insert("a", 100) {
+///     Err(OccupiedError { mut entry, value }) => {
+///         assert_eq!(entry.key(), &"a");
+///         assert_eq!(value, 100);
+///         assert_eq!(entry.insert(100), 10)
+///     }
+///     _ => unreachable!(),
+/// }
+/// assert_eq!(map[&"a"], 100);
+/// ```
+pub struct OccupiedError<'a, K, V, S, A: Allocator = Global> {
+    /// The entry in the map that was already occupied.
+    pub entry: OccupiedEntry<'a, K, V, S, A>,
+    /// The value which was not inserted, because the entry was already occupied.
+    pub value: V,
+}
+
+impl<K: Debug, V: Debug, S, A: Allocator> Debug for OccupiedError<'_, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedError")
+            .field("key", self.entry.key())
+            .field("old_value", self.entry.get())
+            .field("new_value", &self.value)
+            .finish()
+    }
+}
+
+impl<'a, K: Debug, V: Debug, S, A: Allocator> fmt::Display for OccupiedError<'a, K, V, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "failed to insert {:?}, key {:?} already exists with value {:?}",
+            self.value,
+            self.entry.key(),
+            self.entry.get(),
+        )
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> IntoIterator for &'a HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a V);
+    type IntoIter = Iter<'a, K, V>;
+
+    /// Creates an iterator over the entries of a `HashMap` in arbitrary order.
+    /// The iterator element type is `(&'a K, &'a V)`.
+    ///
+    /// Return the same `Iter` struct as by the [`iter`] method on [`HashMap`].
+    ///
+    /// [`iter`]: struct.HashMap.html#method.iter
+    /// [`HashMap`]: struct.HashMap.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let map_one: HashMap<_, _> = [(1, "a"), (2, "b"), (3, "c")].into();
+    /// let mut map_two = HashMap::new();
+    ///
+    /// for (key, value) in &map_one {
+    ///     println!("Key: {}, Value: {}", key, value);
+    ///     map_two.insert_unique_unchecked(*key, *value);
+    /// }
+    ///
+    /// assert_eq!(map_one, map_two);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> Iter<'a, K, V> {
+        self.iter()
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> IntoIterator for &'a mut HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a mut V);
+    type IntoIter = IterMut<'a, K, V>;
+
+    /// Creates an iterator over the entries of a `HashMap` in arbitrary order
+    /// with mutable references to the values. The iterator element type is
+    /// `(&'a K, &'a mut V)`.
+    ///
+    /// Return the same `IterMut` struct as by the [`iter_mut`] method on
+    /// [`HashMap`].
+    ///
+    /// [`iter_mut`]: struct.HashMap.html#method.iter_mut
+    /// [`HashMap`]: struct.HashMap.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// let mut map: HashMap<_, _> = [("a", 1), ("b", 2), ("c", 3)].into();
+    ///
+    /// for (key, value) in &mut map {
+    ///     println!("Key: {}, Value: {}", key, value);
+    ///     *value *= 2;
+    /// }
+    ///
+    /// let mut vec = map.iter().collect::<Vec<_>>();
+    /// // The `Iter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [(&"a", &2), (&"b", &4), (&"c", &6)]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> IterMut<'a, K, V> {
+        self.iter_mut()
+    }
+}
+
+impl<K, V, S, A: Allocator> IntoIterator for HashMap<K, V, S, A> {
+    type Item = (K, V);
+    type IntoIter = IntoIter<K, V, A>;
+
+    /// Creates a consuming iterator, that is, one that moves each key-value
+    /// pair out of the map in arbitrary order. The map cannot be used after
+    /// calling this.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let map: HashMap<_, _> = [("a", 1), ("b", 2), ("c", 3)].into();
+    ///
+    /// // Not possible with .iter()
+    /// let mut vec: Vec<(&str, i32)> = map.into_iter().collect();
+    /// // The `IntoIter` iterator produces items in arbitrary order, so
+    /// // the items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3)]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> IntoIter<K, V, A> {
+        IntoIter {
+            inner: self.table.into_iter(),
+        }
+    }
+}
+
+impl<'a, K, V> Iterator for Iter<'a, K, V> {
+    type Item = (&'a K, &'a V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<(&'a K, &'a V)> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.inner.next() {
+            Some(x) => unsafe {
+                let r = x.as_ref();
+                Some((&r.0, &r.1))
+            },
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<K, V> FusedIterator for Iter<'_, K, V> {}
+
+impl<'a, K, V> Iterator for IterMut<'a, K, V> {
+    type Item = (&'a K, &'a mut V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.inner.next() {
+            Some(x) => unsafe {
+                let r = x.as_mut();
+                Some((&r.0, &mut r.1))
+            },
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V> FusedIterator for IterMut<'_, K, V> {}
+
+impl<K, V> fmt::Debug for IterMut<'_, K, V>
+where
+    K: fmt::Debug,
+    V: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.iter()).finish()
+    }
+}
+
+impl<K, V, A: Allocator> Iterator for IntoIter<K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<(K, V)> {
+        self.inner.next()
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V, A: Allocator> ExactSizeIterator for IntoIter<K, V, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V, A: Allocator> FusedIterator for IntoIter<K, V, A> {}
+
+impl<K: Debug, V: Debug, A: Allocator> fmt::Debug for IntoIter<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.iter()).finish()
+    }
+}
+
+impl<'a, K, V> Iterator for Keys<'a, K, V> {
+    type Item = &'a K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a K> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.inner.next() {
+            Some((k, _)) => Some(k),
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V> FusedIterator for Keys<'_, K, V> {}
+
+impl<'a, K, V> Iterator for Values<'a, K, V> {
+    type Item = &'a V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a V> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.inner.next() {
+            Some((_, v)) => Some(v),
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V> ExactSizeIterator for Values<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V> FusedIterator for Values<'_, K, V> {}
+
+impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
+    type Item = &'a mut V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a mut V> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.inner.next() {
+            Some((_, v)) => Some(v),
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V> FusedIterator for ValuesMut<'_, K, V> {}
+
+impl<K, V: Debug> fmt::Debug for ValuesMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list()
+            .entries(self.inner.iter().map(|(_, val)| val))
+            .finish()
+    }
+}
+
+impl<'a, K, V, A: Allocator> Iterator for Drain<'a, K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<(K, V)> {
+        self.inner.next()
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+impl<K, V, A: Allocator> ExactSizeIterator for Drain<'_, K, V, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+impl<K, V, A: Allocator> FusedIterator for Drain<'_, K, V, A> {}
+
+impl<K, V, A> fmt::Debug for Drain<'_, K, V, A>
+where
+    K: fmt::Debug,
+    V: fmt::Debug,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.iter()).finish()
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> Entry<'a, K, V, S, A> {
+    /// Sets the value of the entry, and returns an OccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let entry = map.entry("horseyland").insert(37);
+    ///
+    /// assert_eq!(entry.key(), &"horseyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> OccupiedEntry<'a, K, V, S, A>
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+            Entry::Vacant(entry) => entry.insert_entry(value),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the default if empty, and returns
+    /// a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry("poneyland").or_insert(3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// // existing key
+    /// *map.entry("poneyland").or_insert(10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self, default: V) -> &'a mut V
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => entry.insert(default),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the default function if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry("poneyland").or_insert_with(|| 3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// // existing key
+    /// *map.entry("poneyland").or_insert_with(|| 10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => entry.insert(default()),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting, if empty, the result of the default function.
+    /// This method allows for generating key-derived values for insertion by providing the default
+    /// function a reference to the key that was moved during the `.entry(key)` method call.
+    ///
+    /// The reference to the moved key is provided so that cloning or copying the key is
+    /// unnecessary, unlike with `.or_insert_with(|| ... )`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, usize> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry("poneyland").or_insert_with_key(|key| key.chars().count());
+    /// assert_eq!(map["poneyland"], 9);
+    ///
+    /// // existing key
+    /// *map.entry("poneyland").or_insert_with_key(|key| key.chars().count() * 10) *= 2;
+    /// assert_eq!(map["poneyland"], 18);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with_key<F: FnOnce(&K) -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => {
+                let value = default(entry.key());
+                entry.insert(value)
+            }
+        }
+    }
+
+    /// Returns a reference to this entry's key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(3);
+    /// // existing key
+    /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
+    /// // nonexistent key
+    /// assert_eq!(map.entry("horseland").key(), &"horseland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        match *self {
+            Entry::Occupied(ref entry) => entry.key(),
+            Entry::Vacant(ref entry) => entry.key(),
+        }
+    }
+
+    /// Provides in-place mutable access to an occupied entry before any
+    /// potential inserts into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 42);
+    ///
+    /// map.entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 43);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_modify<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&mut V),
+    {
+        match self {
+            Entry::Occupied(mut entry) => {
+                f(entry.get_mut());
+                Entry::Occupied(entry)
+            }
+            Entry::Vacant(entry) => Entry::Vacant(entry),
+        }
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// an occupied entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// let entry = map
+    ///     .entry("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| panic!());
+    ///
+    /// match entry {
+    ///     Entry::Vacant(e) => {
+    ///         assert_eq!(e.key(), &"poneyland");
+    ///     }
+    ///     Entry::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// map.insert("poneyland", 42);
+    ///
+    /// let entry = map
+    ///     .entry("poneyland")
+    ///     .and_replace_entry_with(|k, v| {
+    ///         assert_eq!(k, &"poneyland");
+    ///         assert_eq!(v, 42);
+    ///         Some(v + 1)
+    ///     });
+    ///
+    /// match entry {
+    ///     Entry::Occupied(e) => {
+    ///         assert_eq!(e.key(), &"poneyland");
+    ///         assert_eq!(e.get(), &43);
+    ///     }
+    ///     Entry::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 43);
+    ///
+    /// let entry = map
+    ///     .entry("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| None);
+    ///
+    /// match entry {
+    ///     Entry::Vacant(e) => assert_eq!(e.key(), &"poneyland"),
+    ///     Entry::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// assert!(!map.contains_key("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_replace_entry_with<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.replace_entry_with(f),
+            Entry::Vacant(_) => self,
+        }
+    }
+}
+
+impl<'a, K, V: Default, S, A: Allocator> Entry<'a, K, V, S, A> {
+    /// Ensures a value is in the entry by inserting the default value if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry("poneyland").or_default();
+    /// assert_eq!(map["poneyland"], None);
+    ///
+    /// map.insert("horseland", Some(3));
+    ///
+    /// // existing key
+    /// assert_eq!(map.entry("horseland").or_default(), &mut Some(3));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_default(self) -> &'a mut V
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => entry.insert(Default::default()),
+        }
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> OccupiedEntry<'a, K, V, S, A> {
+    /// Gets a reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// match map.entry("poneyland") {
+    ///     Entry::Vacant(_) => panic!(),
+    ///     Entry::Occupied(entry) => assert_eq!(entry.key(), &"poneyland"),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
+    }
+
+    /// Take the ownership of the key and value from the map.
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// if let Entry::Occupied(o) = map.entry("poneyland") {
+    ///     // We delete the entry from the map.
+    ///     assert_eq!(o.remove_entry(), ("poneyland", 12));
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// // Now map hold none elements
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(self) -> (K, V) {
+        unsafe { self.table.table.remove(self.elem).0 }
+    }
+
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// match map.entry("poneyland") {
+    ///     Entry::Vacant(_) => panic!(),
+    ///     Entry::Occupied(entry) => assert_eq!(entry.get(), &12),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &V {
+        unsafe { &self.elem.as_ref().1 }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    ///
+    /// If you need a reference to the `OccupiedEntry` which may outlive the
+    /// destruction of the `Entry` value, see [`into_mut`].
+    ///
+    /// [`into_mut`]: #method.into_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
+    ///     *o.get_mut() += 10;
+    ///     assert_eq!(*o.get(), 22);
+    ///
+    ///     // We can use the same Entry multiple times.
+    ///     *o.get_mut() += 2;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 24);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Converts the OccupiedEntry into a mutable reference to the value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// If you need multiple references to the `OccupiedEntry`, see [`get_mut`].
+    ///
+    /// [`get_mut`]: #method.get_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    ///
+    /// let value: &mut u32;
+    /// match map.entry("poneyland") {
+    ///     Entry::Occupied(entry) => value = entry.into_mut(),
+    ///     Entry::Vacant(_) => panic!(),
+    /// }
+    /// *value += 10;
+    ///
+    /// assert_eq!(map["poneyland"], 22);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
+    ///     assert_eq!(o.insert(15), 12);
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 15);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.entry("poneyland").or_insert(12);
+    ///
+    /// if let Entry::Occupied(o) = map.entry("poneyland") {
+    ///     assert_eq!(o.remove(), 12);
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// // Now map hold none elements
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> V {
+        self.remove_entry().1
+    }
+
+    /// Replaces the entry, returning the old key and value. The new key in the hash map will be
+    /// the key used to create this entry.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if this OccupiedEntry was created through [`Entry::insert`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    ///  use hashbrown::hash_map::{Entry, HashMap};
+    ///  use std::rc::Rc;
+    ///
+    ///  let mut map: HashMap<Rc<String>, u32> = HashMap::new();
+    ///  let key_one = Rc::new("Stringthing".to_string());
+    ///  let key_two = Rc::new("Stringthing".to_string());
+    ///
+    ///  map.insert(key_one.clone(), 15);
+    ///  assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    ///  match map.entry(key_two.clone()) {
+    ///      Entry::Occupied(entry) => {
+    ///          let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
+    ///          assert!(Rc::ptr_eq(&key_one, &old_key) && old_value == 15);
+    ///      }
+    ///      Entry::Vacant(_) => panic!(),
+    ///  }
+    ///
+    ///  assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    ///  assert_eq!(map[&"Stringthing".to_owned()], 16);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry(self, value: V) -> (K, V) {
+        let entry = unsafe { self.elem.as_mut() };
+
+        let old_key = mem::replace(&mut entry.0, self.key.unwrap());
+        let old_value = mem::replace(&mut entry.1, value);
+
+        (old_key, old_value)
+    }
+
+    /// Replaces the key in the hash map with the key used to create this entry.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if this OccupiedEntry was created through [`Entry::insert`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    /// use std::rc::Rc;
+    ///
+    /// let mut map: HashMap<Rc<String>, usize> = HashMap::with_capacity(6);
+    /// let mut keys_one: Vec<Rc<String>> = Vec::with_capacity(6);
+    /// let mut keys_two: Vec<Rc<String>> = Vec::with_capacity(6);
+    ///
+    /// for (value, key) in ["a", "b", "c", "d", "e", "f"].into_iter().enumerate() {
+    ///     let rc_key = Rc::new(key.to_owned());
+    ///     keys_one.push(rc_key.clone());
+    ///     map.insert(rc_key.clone(), value);
+    ///     keys_two.push(Rc::new(key.to_owned()));
+    /// }
+    ///
+    /// assert!(
+    ///     keys_one.iter().all(|key| Rc::strong_count(key) == 2)
+    ///         && keys_two.iter().all(|key| Rc::strong_count(key) == 1)
+    /// );
+    ///
+    /// reclaim_memory(&mut map, &keys_two);
+    ///
+    /// assert!(
+    ///     keys_one.iter().all(|key| Rc::strong_count(key) == 1)
+    ///         && keys_two.iter().all(|key| Rc::strong_count(key) == 2)
+    /// );
+    ///
+    /// fn reclaim_memory(map: &mut HashMap<Rc<String>, usize>, keys: &[Rc<String>]) {
+    ///     for key in keys {
+    ///         if let Entry::Occupied(entry) = map.entry(key.clone()) {
+    ///         // Replaces the entry's key with our version of it in `keys`.
+    ///             entry.replace_key();
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_key(self) -> K {
+        let entry = unsafe { self.elem.as_mut() };
+        mem::replace(&mut entry.0, self.key.unwrap())
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// the entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.insert("poneyland", 42);
+    ///
+    /// let entry = match map.entry("poneyland") {
+    ///     Entry::Occupied(e) => {
+    ///         e.replace_entry_with(|k, v| {
+    ///             assert_eq!(k, &"poneyland");
+    ///             assert_eq!(v, 42);
+    ///             Some(v + 1)
+    ///         })
+    ///     }
+    ///     Entry::Vacant(_) => panic!(),
+    /// };
+    ///
+    /// match entry {
+    ///     Entry::Occupied(e) => {
+    ///         assert_eq!(e.key(), &"poneyland");
+    ///         assert_eq!(e.get(), &43);
+    ///     }
+    ///     Entry::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 43);
+    ///
+    /// let entry = match map.entry("poneyland") {
+    ///     Entry::Occupied(e) => e.replace_entry_with(|_k, _v| None),
+    ///     Entry::Vacant(_) => panic!(),
+    /// };
+    ///
+    /// match entry {
+    ///     Entry::Vacant(e) => {
+    ///         assert_eq!(e.key(), &"poneyland");
+    ///     }
+    ///     Entry::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// assert!(!map.contains_key("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, S, A>
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        unsafe {
+            let mut spare_key = None;
+
+            self.table
+                .table
+                .replace_bucket_with(self.elem.clone(), |(key, value)| {
+                    if let Some(new_value) = f(&key, value) {
+                        Some((key, new_value))
+                    } else {
+                        spare_key = Some(key);
+                        None
+                    }
+                });
+
+            if let Some(key) = spare_key {
+                Entry::Vacant(VacantEntry {
+                    hash: self.hash,
+                    key,
+                    table: self.table,
+                })
+            } else {
+                Entry::Occupied(self)
+            }
+        }
+    }
+}
+
+impl<'a, K, V, S, A: Allocator> VacantEntry<'a, K, V, S, A> {
+    /// Gets a reference to the key that would be used when inserting a value
+    /// through the `VacantEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// assert_eq!(map.entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+
+    /// Take ownership of the key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{Entry, HashMap};
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// match map.entry("poneyland") {
+    ///     Entry::Occupied(_) => panic!(),
+    ///     Entry::Vacant(v) => assert_eq!(v.into_key(), "poneyland"),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    /// Sets the value of the entry with the VacantEntry's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::Entry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let Entry::Vacant(o) = map.entry("poneyland") {
+    ///     o.insert(37);
+    /// }
+    /// assert_eq!(map["poneyland"], 37);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> &'a mut V
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        let table = &mut self.table.table;
+        let entry = table.insert_entry(
+            self.hash,
+            (self.key, value),
+            make_hasher::<_, V, S>(&self.table.hash_builder),
+        );
+        &mut entry.1
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(crate) fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S, A>
+    where
+        K: Hash,
+        S: BuildHasher,
+    {
+        let elem = self.table.table.insert(
+            self.hash,
+            (self.key, value),
+            make_hasher::<_, V, S>(&self.table.hash_builder),
+        );
+        OccupiedEntry {
+            hash: self.hash,
+            key: None,
+            elem,
+            table: self.table,
+        }
+    }
+}
+
+impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> EntryRef<'a, 'b, K, Q, V, S, A> {
+    /// Sets the value of the entry, and returns an OccupiedEntryRef.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// let entry = map.entry_ref("horseyland").insert(37);
+    ///
+    /// assert_eq!(entry.key(), "horseyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        match self {
+            EntryRef::Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+            EntryRef::Vacant(entry) => entry.insert_entry(value),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the default if empty, and returns
+    /// a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry_ref("poneyland").or_insert(3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// // existing key
+    /// *map.entry_ref("poneyland").or_insert(10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self, default: V) -> &'a mut V
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        match self {
+            EntryRef::Occupied(entry) => entry.into_mut(),
+            EntryRef::Vacant(entry) => entry.insert(default),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the default function if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry_ref("poneyland").or_insert_with(|| 3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// // existing key
+    /// *map.entry_ref("poneyland").or_insert_with(|| 10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        match self {
+            EntryRef::Occupied(entry) => entry.into_mut(),
+            EntryRef::Vacant(entry) => entry.insert(default()),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting, if empty, the result of the default function.
+    /// This method allows for generating key-derived values for insertion by providing the default
+    /// function an access to the borrower form of the key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, usize> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry_ref("poneyland").or_insert_with_key(|key| key.chars().count());
+    /// assert_eq!(map["poneyland"], 9);
+    ///
+    /// // existing key
+    /// *map.entry_ref("poneyland").or_insert_with_key(|key| key.chars().count() * 10) *= 2;
+    /// assert_eq!(map["poneyland"], 18);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with_key<F: FnOnce(&Q) -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash + Borrow<Q> + From<&'b Q>,
+        S: BuildHasher,
+    {
+        match self {
+            EntryRef::Occupied(entry) => entry.into_mut(),
+            EntryRef::Vacant(entry) => {
+                let value = default(entry.key.as_ref());
+                entry.insert(value)
+            }
+        }
+    }
+
+    /// Returns a reference to this entry's key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(3);
+    /// // existing key
+    /// assert_eq!(map.entry_ref("poneyland").key(), "poneyland");
+    /// // nonexistent key
+    /// assert_eq!(map.entry_ref("horseland").key(), "horseland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &Q
+    where
+        K: Borrow<Q>,
+    {
+        match *self {
+            EntryRef::Occupied(ref entry) => entry.key().borrow(),
+            EntryRef::Vacant(ref entry) => entry.key(),
+        }
+    }
+
+    /// Provides in-place mutable access to an occupied entry before any
+    /// potential inserts into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    ///
+    /// map.entry_ref("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 42);
+    ///
+    /// map.entry_ref("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 43);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_modify<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&mut V),
+    {
+        match self {
+            EntryRef::Occupied(mut entry) => {
+                f(entry.get_mut());
+                EntryRef::Occupied(entry)
+            }
+            EntryRef::Vacant(entry) => EntryRef::Vacant(entry),
+        }
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// an occupied entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    ///
+    /// let entry = map
+    ///     .entry_ref("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| panic!());
+    ///
+    /// match entry {
+    ///     EntryRef::Vacant(e) => {
+    ///         assert_eq!(e.key(), "poneyland");
+    ///     }
+    ///     EntryRef::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// map.insert("poneyland".to_string(), 42);
+    ///
+    /// let entry = map
+    ///     .entry_ref("poneyland")
+    ///     .and_replace_entry_with(|k, v| {
+    ///         assert_eq!(k, "poneyland");
+    ///         assert_eq!(v, 42);
+    ///         Some(v + 1)
+    ///     });
+    ///
+    /// match entry {
+    ///     EntryRef::Occupied(e) => {
+    ///         assert_eq!(e.key(), "poneyland");
+    ///         assert_eq!(e.get(), &43);
+    ///     }
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 43);
+    ///
+    /// let entry = map
+    ///     .entry_ref("poneyland")
+    ///     .and_replace_entry_with(|_k, _v| None);
+    ///
+    /// match entry {
+    ///     EntryRef::Vacant(e) => assert_eq!(e.key(), "poneyland"),
+    ///     EntryRef::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// assert!(!map.contains_key("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_replace_entry_with<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        match self {
+            EntryRef::Occupied(entry) => entry.replace_entry_with(f),
+            EntryRef::Vacant(_) => self,
+        }
+    }
+}
+
+impl<'a, 'b, K, Q: ?Sized, V: Default, S, A: Allocator> EntryRef<'a, 'b, K, Q, V, S, A> {
+    /// Ensures a value is in the entry by inserting the default value if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, Option<u32>> = HashMap::new();
+    ///
+    /// // nonexistent key
+    /// map.entry_ref("poneyland").or_default();
+    /// assert_eq!(map["poneyland"], None);
+    ///
+    /// map.insert("horseland".to_string(), Some(3));
+    ///
+    /// // existing key
+    /// assert_eq!(map.entry_ref("horseland").or_default(), &mut Some(3));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_default(self) -> &'a mut V
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        match self {
+            EntryRef::Occupied(entry) => entry.into_mut(),
+            EntryRef::Vacant(entry) => entry.insert(Default::default()),
+        }
+    }
+}
+
+impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> OccupiedEntryRef<'a, 'b, K, Q, V, S, A> {
+    /// Gets a reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// match map.entry_ref("poneyland") {
+    ///     EntryRef::Vacant(_) => panic!(),
+    ///     EntryRef::Occupied(entry) => assert_eq!(entry.key(), "poneyland"),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
+    }
+
+    /// Take the ownership of the key and value from the map.
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// if let EntryRef::Occupied(o) = map.entry_ref("poneyland") {
+    ///     // We delete the entry from the map.
+    ///     assert_eq!(o.remove_entry(), ("poneyland".to_owned(), 12));
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// // Now map hold none elements but capacity is equal to the old one
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(self) -> (K, V) {
+        unsafe { self.table.table.remove(self.elem).0 }
+    }
+
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// match map.entry_ref("poneyland") {
+    ///     EntryRef::Vacant(_) => panic!(),
+    ///     EntryRef::Occupied(entry) => assert_eq!(entry.get(), &12),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &V {
+        unsafe { &self.elem.as_ref().1 }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    ///
+    /// If you need a reference to the `OccupiedEntryRef` which may outlive the
+    /// destruction of the `EntryRef` value, see [`into_mut`].
+    ///
+    /// [`into_mut`]: #method.into_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let EntryRef::Occupied(mut o) = map.entry_ref("poneyland") {
+    ///     *o.get_mut() += 10;
+    ///     assert_eq!(*o.get(), 22);
+    ///
+    ///     // We can use the same Entry multiple times.
+    ///     *o.get_mut() += 2;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 24);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Converts the OccupiedEntryRef into a mutable reference to the value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// If you need multiple references to the `OccupiedEntryRef`, see [`get_mut`].
+    ///
+    /// [`get_mut`]: #method.get_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// let value: &mut u32;
+    /// match map.entry_ref("poneyland") {
+    ///     EntryRef::Occupied(entry) => value = entry.into_mut(),
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// }
+    /// *value += 10;
+    ///
+    /// assert_eq!(map["poneyland"], 22);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// if let EntryRef::Occupied(mut o) = map.entry_ref("poneyland") {
+    ///     assert_eq!(o.insert(15), 12);
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 15);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// // The map is empty
+    /// assert!(map.is_empty() && map.capacity() == 0);
+    ///
+    /// map.entry_ref("poneyland").or_insert(12);
+    ///
+    /// if let EntryRef::Occupied(o) = map.entry_ref("poneyland") {
+    ///     assert_eq!(o.remove(), 12);
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// // Now map hold none elements but capacity is equal to the old one
+    /// assert!(map.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> V {
+        self.remove_entry().1
+    }
+
+    /// Replaces the entry, returning the old key and value. The new key in the hash map will be
+    /// the key used to create this entry.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if this OccupiedEntryRef was created through [`EntryRef::insert`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    /// use std::rc::Rc;
+    ///
+    /// let mut map: HashMap<Rc<str>, u32> = HashMap::new();
+    /// let key: Rc<str> = Rc::from("Stringthing");
+    ///
+    /// map.insert(key.clone(), 15);
+    /// assert_eq!(Rc::strong_count(&key), 2);
+    ///
+    /// match map.entry_ref("Stringthing") {
+    ///     EntryRef::Occupied(entry) => {
+    ///         let (old_key, old_value): (Rc<str>, u32) = entry.replace_entry(16);
+    ///         assert!(Rc::ptr_eq(&key, &old_key) && old_value == 15);
+    ///     }
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(Rc::strong_count(&key), 1);
+    /// assert_eq!(map["Stringthing"], 16);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry(self, value: V) -> (K, V)
+    where
+        K: From<&'b Q>,
+    {
+        let entry = unsafe { self.elem.as_mut() };
+
+        let old_key = mem::replace(&mut entry.0, self.key.unwrap().into_owned());
+        let old_value = mem::replace(&mut entry.1, value);
+
+        (old_key, old_value)
+    }
+
+    /// Replaces the key in the hash map with the key used to create this entry.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if this OccupiedEntryRef was created through [`EntryRef::insert`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    /// use std::rc::Rc;
+    ///
+    /// let mut map: HashMap<Rc<str>, usize> = HashMap::with_capacity(6);
+    /// let mut keys: Vec<Rc<str>> = Vec::with_capacity(6);
+    ///
+    /// for (value, key) in ["a", "b", "c", "d", "e", "f"].into_iter().enumerate() {
+    ///     let rc_key: Rc<str> = Rc::from(key);
+    ///     keys.push(rc_key.clone());
+    ///     map.insert(rc_key.clone(), value);
+    /// }
+    ///
+    /// assert!(keys.iter().all(|key| Rc::strong_count(key) == 2));
+    ///
+    /// // It doesn't matter that we kind of use a vector with the same keys,
+    /// // because all keys will be newly created from the references
+    /// reclaim_memory(&mut map, &keys);
+    ///
+    /// assert!(keys.iter().all(|key| Rc::strong_count(key) == 1));
+    ///
+    /// fn reclaim_memory(map: &mut HashMap<Rc<str>, usize>, keys: &[Rc<str>]) {
+    ///     for key in keys {
+    ///         if let EntryRef::Occupied(entry) = map.entry_ref(key.as_ref()) {
+    ///             // Replaces the entry's key with our version of it in `keys`.
+    ///             entry.replace_key();
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_key(self) -> K
+    where
+        K: From<&'b Q>,
+    {
+        let entry = unsafe { self.elem.as_mut() };
+        mem::replace(&mut entry.0, self.key.unwrap().into_owned())
+    }
+
+    /// Provides shared access to the key and owned access to the value of
+    /// the entry and allows to replace or remove it based on the
+    /// value of the returned option.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// map.insert("poneyland".to_string(), 42);
+    ///
+    /// let entry = match map.entry_ref("poneyland") {
+    ///     EntryRef::Occupied(e) => {
+    ///         e.replace_entry_with(|k, v| {
+    ///             assert_eq!(k, "poneyland");
+    ///             assert_eq!(v, 42);
+    ///             Some(v + 1)
+    ///         })
+    ///     }
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// };
+    ///
+    /// match entry {
+    ///     EntryRef::Occupied(e) => {
+    ///         assert_eq!(e.key(), "poneyland");
+    ///         assert_eq!(e.get(), &43);
+    ///     }
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 43);
+    ///
+    /// let entry = match map.entry_ref("poneyland") {
+    ///     EntryRef::Occupied(e) => e.replace_entry_with(|_k, _v| None),
+    ///     EntryRef::Vacant(_) => panic!(),
+    /// };
+    ///
+    /// match entry {
+    ///     EntryRef::Vacant(e) => {
+    ///         assert_eq!(e.key(), "poneyland");
+    ///     }
+    ///     EntryRef::Occupied(_) => panic!(),
+    /// }
+    ///
+    /// assert!(!map.contains_key("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry_with<F>(self, f: F) -> EntryRef<'a, 'b, K, Q, V, S, A>
+    where
+        F: FnOnce(&K, V) -> Option<V>,
+    {
+        unsafe {
+            let mut spare_key = None;
+
+            self.table
+                .table
+                .replace_bucket_with(self.elem.clone(), |(key, value)| {
+                    if let Some(new_value) = f(&key, value) {
+                        Some((key, new_value))
+                    } else {
+                        spare_key = Some(KeyOrRef::Owned(key));
+                        None
+                    }
+                });
+
+            if let Some(key) = spare_key {
+                EntryRef::Vacant(VacantEntryRef {
+                    hash: self.hash,
+                    key,
+                    table: self.table,
+                })
+            } else {
+                EntryRef::Occupied(self)
+            }
+        }
+    }
+}
+
+impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator> VacantEntryRef<'a, 'b, K, Q, V, S, A> {
+    /// Gets a reference to the key that would be used when inserting a value
+    /// through the `VacantEntryRef`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// let key: &str = "poneyland";
+    /// assert_eq!(map.entry_ref(key).key(), "poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &Q
+    where
+        K: Borrow<Q>,
+    {
+        self.key.as_ref()
+    }
+
+    /// Take ownership of the key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{EntryRef, HashMap};
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// let key: &str = "poneyland";
+    ///
+    /// match map.entry_ref(key) {
+    ///     EntryRef::Occupied(_) => panic!(),
+    ///     EntryRef::Vacant(v) => assert_eq!(v.into_key(), "poneyland".to_owned()),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key(self) -> K
+    where
+        K: From<&'b Q>,
+    {
+        self.key.into_owned()
+    }
+
+    /// Sets the value of the entry with the VacantEntryRef's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::EntryRef;
+    ///
+    /// let mut map: HashMap<String, u32> = HashMap::new();
+    /// let key: &str = "poneyland";
+    ///
+    /// if let EntryRef::Vacant(o) = map.entry_ref(key) {
+    ///     o.insert(37);
+    /// }
+    /// assert_eq!(map["poneyland"], 37);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> &'a mut V
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        let table = &mut self.table.table;
+        let entry = table.insert_entry(
+            self.hash,
+            (self.key.into_owned(), value),
+            make_hasher::<_, V, S>(&self.table.hash_builder),
+        );
+        &mut entry.1
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn insert_entry(self, value: V) -> OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
+    where
+        K: Hash + From<&'b Q>,
+        S: BuildHasher,
+    {
+        let elem = self.table.table.insert(
+            self.hash,
+            (self.key.into_owned(), value),
+            make_hasher::<_, V, S>(&self.table.hash_builder),
+        );
+        OccupiedEntryRef {
+            hash: self.hash,
+            key: None,
+            elem,
+            table: self.table,
+        }
+    }
+}
+
+impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    S: BuildHasher + Default,
+    A: Default + Allocator,
+{
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
+        let iter = iter.into_iter();
+        let mut map =
+            Self::with_capacity_and_hasher_in(iter.size_hint().0, S::default(), A::default());
+        iter.for_each(|(k, v)| {
+            map.insert(k, v);
+        });
+        map
+    }
+}
+
+/// Inserts all new key-values from the iterator and replaces values with existing
+/// keys with new values returned from the iterator.
+impl<K, V, S, A> Extend<(K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
+    /// Replace values with existing keys with new values returned from the iterator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, 100);
+    ///
+    /// let some_iter = [(1, 1), (2, 2)].into_iter();
+    /// map.extend(some_iter);
+    /// // Replace values with existing keys with new values returned from the iterator.
+    /// // So that the map.get(&1) doesn't return Some(&100).
+    /// assert_eq!(map.get(&1), Some(&1));
+    ///
+    /// let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
+    /// map.extend(some_vec);
+    ///
+    /// let some_arr = [(5, 5), (6, 6)];
+    /// map.extend(some_arr);
+    /// let old_map_len = map.len();
+    ///
+    /// // You can also extend from another HashMap
+    /// let mut new_map = HashMap::new();
+    /// new_map.extend(map);
+    /// assert_eq!(new_map.len(), old_map_len);
+    ///
+    /// let mut vec: Vec<_> = new_map.into_iter().collect();
+    /// // The `IntoIter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
+        // Keys may be already present or show multiple times in the iterator.
+        // Reserve the entire hint lower bound if the map is empty.
+        // Otherwise reserve half the hint (rounded up), so the map
+        // will only resize twice in the worst case.
+        let iter = iter.into_iter();
+        let reserve = if self.is_empty() {
+            iter.size_hint().0
+        } else {
+            (iter.size_hint().0 + 1) / 2
+        };
+        self.reserve(reserve);
+        iter.for_each(move |(k, v)| {
+            self.insert(k, v);
+        });
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_one(&mut self, (k, v): (K, V)) {
+        self.insert(k, v);
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_reserve(&mut self, additional: usize) {
+        // Keys may be already present or show multiple times in the iterator.
+        // Reserve the entire hint lower bound if the map is empty.
+        // Otherwise reserve half the hint (rounded up), so the map
+        // will only resize twice in the worst case.
+        let reserve = if self.is_empty() {
+            additional
+        } else {
+            (additional + 1) / 2
+        };
+        self.reserve(reserve);
+    }
+}
+
+/// Inserts all new key-values from the iterator and replaces values with existing
+/// keys with new values returned from the iterator.
+impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Copy,
+    V: Copy,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
+    /// Replace values with existing keys with new values returned from the iterator.
+    /// The keys and values must implement [`Copy`] trait.
+    ///
+    /// [`Copy`]: https://doc.rust-lang.org/core/marker/trait.Copy.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, 100);
+    ///
+    /// let arr = [(1, 1), (2, 2)];
+    /// let some_iter = arr.iter().map(|(k, v)| (k, v));
+    /// map.extend(some_iter);
+    /// // Replace values with existing keys with new values returned from the iterator.
+    /// // So that the map.get(&1) doesn't return Some(&100).
+    /// assert_eq!(map.get(&1), Some(&1));
+    ///
+    /// let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
+    /// map.extend(some_vec.iter().map(|(k, v)| (k, v)));
+    ///
+    /// let some_arr = [(5, 5), (6, 6)];
+    /// map.extend(some_arr.iter().map(|(k, v)| (k, v)));
+    ///
+    /// // You can also extend from another HashMap
+    /// let mut new_map = HashMap::new();
+    /// new_map.extend(&map);
+    /// assert_eq!(new_map, map);
+    ///
+    /// let mut vec: Vec<_> = new_map.into_iter().collect();
+    /// // The `IntoIter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) {
+        self.extend(iter.into_iter().map(|(&key, &value)| (key, value)));
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_one(&mut self, (k, v): (&'a K, &'a V)) {
+        self.insert(*k, *v);
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_reserve(&mut self, additional: usize) {
+        Extend::<(K, V)>::extend_reserve(self, additional);
+    }
+}
+
+/// Inserts all new key-values from the iterator and replaces values with existing
+/// keys with new values returned from the iterator.
+impl<'a, K, V, S, A> Extend<&'a (K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Copy,
+    V: Copy,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Inserts all new key-values from the iterator to existing `HashMap<K, V, S, A>`.
+    /// Replace values with existing keys with new values returned from the iterator.
+    /// The keys and values must implement [`Copy`] trait.
+    ///
+    /// [`Copy`]: https://doc.rust-lang.org/core/marker/trait.Copy.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::HashMap;
+    ///
+    /// let mut map = HashMap::new();
+    /// map.insert(1, 100);
+    ///
+    /// let arr = [(1, 1), (2, 2)];
+    /// let some_iter = arr.iter();
+    /// map.extend(some_iter);
+    /// // Replace values with existing keys with new values returned from the iterator.
+    /// // So that the map.get(&1) doesn't return Some(&100).
+    /// assert_eq!(map.get(&1), Some(&1));
+    ///
+    /// let some_vec: Vec<_> = vec![(3, 3), (4, 4)];
+    /// map.extend(&some_vec);
+    ///
+    /// let some_arr = [(5, 5), (6, 6)];
+    /// map.extend(&some_arr);
+    ///
+    /// let mut vec: Vec<_> = map.into_iter().collect();
+    /// // The `IntoIter` iterator produces items in arbitrary order, so the
+    /// // items must be sorted to test them against a sorted array.
+    /// vec.sort_unstable();
+    /// assert_eq!(vec, [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn extend<T: IntoIterator<Item = &'a (K, V)>>(&mut self, iter: T) {
+        self.extend(iter.into_iter().map(|&(key, value)| (key, value)));
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_one(&mut self, &(k, v): &'a (K, V)) {
+        self.insert(k, v);
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_reserve(&mut self, additional: usize) {
+        Extend::<(K, V)>::extend_reserve(self, additional);
+    }
+}
+
+#[allow(dead_code)]
+fn assert_covariance() {
+    fn map_key<'new>(v: HashMap<&'static str, u8>) -> HashMap<&'new str, u8> {
+        v
+    }
+    fn map_val<'new>(v: HashMap<u8, &'static str>) -> HashMap<u8, &'new str> {
+        v
+    }
+    fn iter_key<'a, 'new>(v: Iter<'a, &'static str, u8>) -> Iter<'a, &'new str, u8> {
+        v
+    }
+    fn iter_val<'a, 'new>(v: Iter<'a, u8, &'static str>) -> Iter<'a, u8, &'new str> {
+        v
+    }
+    fn into_iter_key<'new, A: Allocator>(
+        v: IntoIter<&'static str, u8, A>,
+    ) -> IntoIter<&'new str, u8, A> {
+        v
+    }
+    fn into_iter_val<'new, A: Allocator>(
+        v: IntoIter<u8, &'static str, A>,
+    ) -> IntoIter<u8, &'new str, A> {
+        v
+    }
+    fn keys_key<'a, 'new>(v: Keys<'a, &'static str, u8>) -> Keys<'a, &'new str, u8> {
+        v
+    }
+    fn keys_val<'a, 'new>(v: Keys<'a, u8, &'static str>) -> Keys<'a, u8, &'new str> {
+        v
+    }
+    fn values_key<'a, 'new>(v: Values<'a, &'static str, u8>) -> Values<'a, &'new str, u8> {
+        v
+    }
+    fn values_val<'a, 'new>(v: Values<'a, u8, &'static str>) -> Values<'a, u8, &'new str> {
+        v
+    }
+    fn drain<'new>(
+        d: Drain<'static, &'static str, &'static str>,
+    ) -> Drain<'new, &'new str, &'new str> {
+        d
+    }
+}
+
+#[cfg(test)]
+mod test_map {
+    use super::DefaultHashBuilder;
+    use super::Entry::{Occupied, Vacant};
+    use super::EntryRef;
+    use super::{HashMap, RawEntryMut};
+    use alloc::string::{String, ToString};
+    use alloc::sync::Arc;
+    use allocator_api2::alloc::{AllocError, Allocator, Global};
+    use core::alloc::Layout;
+    use core::ptr::NonNull;
+    use core::sync::atomic::{AtomicI8, Ordering};
+    use rand::{rngs::SmallRng, Rng, SeedableRng};
+    use std::borrow::ToOwned;
+    use std::cell::RefCell;
+    use std::usize;
+    use std::vec::Vec;
+
+    #[test]
+    fn test_zero_capacities() {
+        type HM = HashMap<i32, i32>;
+
+        let m = HM::new();
+        assert_eq!(m.capacity(), 0);
+
+        let m = HM::default();
+        assert_eq!(m.capacity(), 0);
+
+        let m = HM::with_hasher(DefaultHashBuilder::default());
+        assert_eq!(m.capacity(), 0);
+
+        let m = HM::with_capacity(0);
+        assert_eq!(m.capacity(), 0);
+
+        let m = HM::with_capacity_and_hasher(0, DefaultHashBuilder::default());
+        assert_eq!(m.capacity(), 0);
+
+        let mut m = HM::new();
+        m.insert(1, 1);
+        m.insert(2, 2);
+        m.remove(&1);
+        m.remove(&2);
+        m.shrink_to_fit();
+        assert_eq!(m.capacity(), 0);
+
+        let mut m = HM::new();
+        m.reserve(0);
+        assert_eq!(m.capacity(), 0);
+    }
+
+    #[test]
+    fn test_create_capacity_zero() {
+        let mut m = HashMap::with_capacity(0);
+
+        assert!(m.insert(1, 1).is_none());
+
+        assert!(m.contains_key(&1));
+        assert!(!m.contains_key(&0));
+    }
+
+    #[test]
+    fn test_insert() {
+        let mut m = HashMap::new();
+        assert_eq!(m.len(), 0);
+        assert!(m.insert(1, 2).is_none());
+        assert_eq!(m.len(), 1);
+        assert!(m.insert(2, 4).is_none());
+        assert_eq!(m.len(), 2);
+        assert_eq!(*m.get(&1).unwrap(), 2);
+        assert_eq!(*m.get(&2).unwrap(), 4);
+    }
+
+    #[test]
+    fn test_clone() {
+        let mut m = HashMap::new();
+        assert_eq!(m.len(), 0);
+        assert!(m.insert(1, 2).is_none());
+        assert_eq!(m.len(), 1);
+        assert!(m.insert(2, 4).is_none());
+        assert_eq!(m.len(), 2);
+        #[allow(clippy::redundant_clone)]
+        let m2 = m.clone();
+        assert_eq!(*m2.get(&1).unwrap(), 2);
+        assert_eq!(*m2.get(&2).unwrap(), 4);
+        assert_eq!(m2.len(), 2);
+    }
+
+    #[test]
+    fn test_clone_from() {
+        let mut m = HashMap::new();
+        let mut m2 = HashMap::new();
+        assert_eq!(m.len(), 0);
+        assert!(m.insert(1, 2).is_none());
+        assert_eq!(m.len(), 1);
+        assert!(m.insert(2, 4).is_none());
+        assert_eq!(m.len(), 2);
+        m2.clone_from(&m);
+        assert_eq!(*m2.get(&1).unwrap(), 2);
+        assert_eq!(*m2.get(&2).unwrap(), 4);
+        assert_eq!(m2.len(), 2);
+    }
+
+    thread_local! { static DROP_VECTOR: RefCell<Vec<i32>> = RefCell::new(Vec::new()) }
+
+    #[derive(Hash, PartialEq, Eq)]
+    struct Droppable {
+        k: usize,
+    }
+
+    impl Droppable {
+        fn new(k: usize) -> Droppable {
+            DROP_VECTOR.with(|slot| {
+                slot.borrow_mut()[k] += 1;
+            });
+
+            Droppable { k }
+        }
+    }
+
+    impl Drop for Droppable {
+        fn drop(&mut self) {
+            DROP_VECTOR.with(|slot| {
+                slot.borrow_mut()[self.k] -= 1;
+            });
+        }
+    }
+
+    impl Clone for Droppable {
+        fn clone(&self) -> Self {
+            Droppable::new(self.k)
+        }
+    }
+
+    #[test]
+    fn test_drops() {
+        DROP_VECTOR.with(|slot| {
+            *slot.borrow_mut() = vec![0; 200];
+        });
+
+        {
+            let mut m = HashMap::new();
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..200 {
+                    assert_eq!(v.borrow()[i], 0);
+                }
+            });
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i);
+                let d2 = Droppable::new(i + 100);
+                m.insert(d1, d2);
+            }
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..200 {
+                    assert_eq!(v.borrow()[i], 1);
+                }
+            });
+
+            for i in 0..50 {
+                let k = Droppable::new(i);
+                let v = m.remove(&k);
+
+                assert!(v.is_some());
+
+                DROP_VECTOR.with(|v| {
+                    assert_eq!(v.borrow()[i], 1);
+                    assert_eq!(v.borrow()[i + 100], 1);
+                });
+            }
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..50 {
+                    assert_eq!(v.borrow()[i], 0);
+                    assert_eq!(v.borrow()[i + 100], 0);
+                }
+
+                for i in 50..100 {
+                    assert_eq!(v.borrow()[i], 1);
+                    assert_eq!(v.borrow()[i + 100], 1);
+                }
+            });
+        }
+
+        DROP_VECTOR.with(|v| {
+            for i in 0..200 {
+                assert_eq!(v.borrow()[i], 0);
+            }
+        });
+    }
+
+    #[test]
+    fn test_into_iter_drops() {
+        DROP_VECTOR.with(|v| {
+            *v.borrow_mut() = vec![0; 200];
+        });
+
+        let hm = {
+            let mut hm = HashMap::new();
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..200 {
+                    assert_eq!(v.borrow()[i], 0);
+                }
+            });
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i);
+                let d2 = Droppable::new(i + 100);
+                hm.insert(d1, d2);
+            }
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..200 {
+                    assert_eq!(v.borrow()[i], 1);
+                }
+            });
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        {
+            let mut half = hm.into_iter().take(50);
+
+            DROP_VECTOR.with(|v| {
+                for i in 0..200 {
+                    assert_eq!(v.borrow()[i], 1);
+                }
+            });
+
+            for _ in half.by_ref() {}
+
+            DROP_VECTOR.with(|v| {
+                let nk = (0..100).filter(|&i| v.borrow()[i] == 1).count();
+
+                let nv = (0..100).filter(|&i| v.borrow()[i + 100] == 1).count();
+
+                assert_eq!(nk, 50);
+                assert_eq!(nv, 50);
+            });
+        };
+
+        DROP_VECTOR.with(|v| {
+            for i in 0..200 {
+                assert_eq!(v.borrow()[i], 0);
+            }
+        });
+    }
+
+    #[test]
+    fn test_empty_remove() {
+        let mut m: HashMap<i32, bool> = HashMap::new();
+        assert_eq!(m.remove(&0), None);
+    }
+
+    #[test]
+    fn test_empty_entry() {
+        let mut m: HashMap<i32, bool> = HashMap::new();
+        match m.entry(0) {
+            Occupied(_) => panic!(),
+            Vacant(_) => {}
+        }
+        assert!(*m.entry(0).or_insert(true));
+        assert_eq!(m.len(), 1);
+    }
+
+    #[test]
+    fn test_empty_entry_ref() {
+        let mut m: HashMap<std::string::String, bool> = HashMap::new();
+        match m.entry_ref("poneyland") {
+            EntryRef::Occupied(_) => panic!(),
+            EntryRef::Vacant(_) => {}
+        }
+        assert!(*m.entry_ref("poneyland").or_insert(true));
+        assert_eq!(m.len(), 1);
+    }
+
+    #[test]
+    fn test_empty_iter() {
+        let mut m: HashMap<i32, bool> = HashMap::new();
+        assert_eq!(m.drain().next(), None);
+        assert_eq!(m.keys().next(), None);
+        assert_eq!(m.values().next(), None);
+        assert_eq!(m.values_mut().next(), None);
+        assert_eq!(m.iter().next(), None);
+        assert_eq!(m.iter_mut().next(), None);
+        assert_eq!(m.len(), 0);
+        assert!(m.is_empty());
+        assert_eq!(m.into_iter().next(), None);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)] // FIXME: takes too long
+    fn test_lots_of_insertions() {
+        let mut m = HashMap::new();
+
+        // Try this a few times to make sure we never screw up the hashmap's
+        // internal state.
+        for _ in 0..10 {
+            assert!(m.is_empty());
+
+            for i in 1..1001 {
+                assert!(m.insert(i, i).is_none());
+
+                for j in 1..=i {
+                    let r = m.get(&j);
+                    assert_eq!(r, Some(&j));
+                }
+
+                for j in i + 1..1001 {
+                    let r = m.get(&j);
+                    assert_eq!(r, None);
+                }
+            }
+
+            for i in 1001..2001 {
+                assert!(!m.contains_key(&i));
+            }
+
+            // remove forwards
+            for i in 1..1001 {
+                assert!(m.remove(&i).is_some());
+
+                for j in 1..=i {
+                    assert!(!m.contains_key(&j));
+                }
+
+                for j in i + 1..1001 {
+                    assert!(m.contains_key(&j));
+                }
+            }
+
+            for i in 1..1001 {
+                assert!(!m.contains_key(&i));
+            }
+
+            for i in 1..1001 {
+                assert!(m.insert(i, i).is_none());
+            }
+
+            // remove backwards
+            for i in (1..1001).rev() {
+                assert!(m.remove(&i).is_some());
+
+                for j in i..1001 {
+                    assert!(!m.contains_key(&j));
+                }
+
+                for j in 1..i {
+                    assert!(m.contains_key(&j));
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_find_mut() {
+        let mut m = HashMap::new();
+        assert!(m.insert(1, 12).is_none());
+        assert!(m.insert(2, 8).is_none());
+        assert!(m.insert(5, 14).is_none());
+        let new = 100;
+        match m.get_mut(&5) {
+            None => panic!(),
+            Some(x) => *x = new,
+        }
+        assert_eq!(m.get(&5), Some(&new));
+    }
+
+    #[test]
+    fn test_insert_overwrite() {
+        let mut m = HashMap::new();
+        assert!(m.insert(1, 2).is_none());
+        assert_eq!(*m.get(&1).unwrap(), 2);
+        assert!(m.insert(1, 3).is_some());
+        assert_eq!(*m.get(&1).unwrap(), 3);
+    }
+
+    #[test]
+    fn test_insert_conflicts() {
+        let mut m = HashMap::with_capacity(4);
+        assert!(m.insert(1, 2).is_none());
+        assert!(m.insert(5, 3).is_none());
+        assert!(m.insert(9, 4).is_none());
+        assert_eq!(*m.get(&9).unwrap(), 4);
+        assert_eq!(*m.get(&5).unwrap(), 3);
+        assert_eq!(*m.get(&1).unwrap(), 2);
+    }
+
+    #[test]
+    fn test_conflict_remove() {
+        let mut m = HashMap::with_capacity(4);
+        assert!(m.insert(1, 2).is_none());
+        assert_eq!(*m.get(&1).unwrap(), 2);
+        assert!(m.insert(5, 3).is_none());
+        assert_eq!(*m.get(&1).unwrap(), 2);
+        assert_eq!(*m.get(&5).unwrap(), 3);
+        assert!(m.insert(9, 4).is_none());
+        assert_eq!(*m.get(&1).unwrap(), 2);
+        assert_eq!(*m.get(&5).unwrap(), 3);
+        assert_eq!(*m.get(&9).unwrap(), 4);
+        assert!(m.remove(&1).is_some());
+        assert_eq!(*m.get(&9).unwrap(), 4);
+        assert_eq!(*m.get(&5).unwrap(), 3);
+    }
+
+    #[test]
+    fn test_insert_unique_unchecked() {
+        let mut map = HashMap::new();
+        let (k1, v1) = map.insert_unique_unchecked(10, 11);
+        assert_eq!((&10, &mut 11), (k1, v1));
+        let (k2, v2) = map.insert_unique_unchecked(20, 21);
+        assert_eq!((&20, &mut 21), (k2, v2));
+        assert_eq!(Some(&11), map.get(&10));
+        assert_eq!(Some(&21), map.get(&20));
+        assert_eq!(None, map.get(&30));
+    }
+
+    #[test]
+    fn test_is_empty() {
+        let mut m = HashMap::with_capacity(4);
+        assert!(m.insert(1, 2).is_none());
+        assert!(!m.is_empty());
+        assert!(m.remove(&1).is_some());
+        assert!(m.is_empty());
+    }
+
+    #[test]
+    fn test_remove() {
+        let mut m = HashMap::new();
+        m.insert(1, 2);
+        assert_eq!(m.remove(&1), Some(2));
+        assert_eq!(m.remove(&1), None);
+    }
+
+    #[test]
+    fn test_remove_entry() {
+        let mut m = HashMap::new();
+        m.insert(1, 2);
+        assert_eq!(m.remove_entry(&1), Some((1, 2)));
+        assert_eq!(m.remove(&1), None);
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut m = HashMap::with_capacity(4);
+        for i in 0..32 {
+            assert!(m.insert(i, i * 2).is_none());
+        }
+        assert_eq!(m.len(), 32);
+
+        let mut observed: u32 = 0;
+
+        for (k, v) in &m {
+            assert_eq!(*v, *k * 2);
+            observed |= 1 << *k;
+        }
+        assert_eq!(observed, 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_keys() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_iter().collect();
+        let keys: Vec<_> = map.keys().copied().collect();
+        assert_eq!(keys.len(), 3);
+        assert!(keys.contains(&1));
+        assert!(keys.contains(&2));
+        assert!(keys.contains(&3));
+    }
+
+    #[test]
+    fn test_values() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_iter().collect();
+        let values: Vec<_> = map.values().copied().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&'a'));
+        assert!(values.contains(&'b'));
+        assert!(values.contains(&'c'));
+    }
+
+    #[test]
+    fn test_values_mut() {
+        let vec = vec![(1, 1), (2, 2), (3, 3)];
+        let mut map: HashMap<_, _> = vec.into_iter().collect();
+        for value in map.values_mut() {
+            *value *= 2;
+        }
+        let values: Vec<_> = map.values().copied().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&2));
+        assert!(values.contains(&4));
+        assert!(values.contains(&6));
+    }
+
+    #[test]
+    fn test_into_keys() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_iter().collect();
+        let keys: Vec<_> = map.into_keys().collect();
+
+        assert_eq!(keys.len(), 3);
+        assert!(keys.contains(&1));
+        assert!(keys.contains(&2));
+        assert!(keys.contains(&3));
+    }
+
+    #[test]
+    fn test_into_values() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_iter().collect();
+        let values: Vec<_> = map.into_values().collect();
+
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&'a'));
+        assert!(values.contains(&'b'));
+        assert!(values.contains(&'c'));
+    }
+
+    #[test]
+    fn test_find() {
+        let mut m = HashMap::new();
+        assert!(m.get(&1).is_none());
+        m.insert(1, 2);
+        match m.get(&1) {
+            None => panic!(),
+            Some(v) => assert_eq!(*v, 2),
+        }
+    }
+
+    #[test]
+    fn test_eq() {
+        let mut m1 = HashMap::new();
+        m1.insert(1, 2);
+        m1.insert(2, 3);
+        m1.insert(3, 4);
+
+        let mut m2 = HashMap::new();
+        m2.insert(1, 2);
+        m2.insert(2, 3);
+
+        assert!(m1 != m2);
+
+        m2.insert(3, 4);
+
+        assert_eq!(m1, m2);
+    }
+
+    #[test]
+    fn test_show() {
+        let mut map = HashMap::new();
+        let empty: HashMap<i32, i32> = HashMap::new();
+
+        map.insert(1, 2);
+        map.insert(3, 4);
+
+        let map_str = format!("{map:?}");
+
+        assert!(map_str == "{1: 2, 3: 4}" || map_str == "{3: 4, 1: 2}");
+        assert_eq!(format!("{empty:?}"), "{}");
+    }
+
+    #[test]
+    fn test_expand() {
+        let mut m = HashMap::new();
+
+        assert_eq!(m.len(), 0);
+        assert!(m.is_empty());
+
+        let mut i = 0;
+        let old_raw_cap = m.raw_capacity();
+        while old_raw_cap == m.raw_capacity() {
+            m.insert(i, i);
+            i += 1;
+        }
+
+        assert_eq!(m.len(), i);
+        assert!(!m.is_empty());
+    }
+
+    #[test]
+    fn test_behavior_resize_policy() {
+        let mut m = HashMap::new();
+
+        assert_eq!(m.len(), 0);
+        assert_eq!(m.raw_capacity(), 1);
+        assert!(m.is_empty());
+
+        m.insert(0, 0);
+        m.remove(&0);
+        assert!(m.is_empty());
+        let initial_raw_cap = m.raw_capacity();
+        m.reserve(initial_raw_cap);
+        let raw_cap = m.raw_capacity();
+
+        assert_eq!(raw_cap, initial_raw_cap * 2);
+
+        let mut i = 0;
+        for _ in 0..raw_cap * 3 / 4 {
+            m.insert(i, i);
+            i += 1;
+        }
+        // three quarters full
+
+        assert_eq!(m.len(), i);
+        assert_eq!(m.raw_capacity(), raw_cap);
+
+        for _ in 0..raw_cap / 4 {
+            m.insert(i, i);
+            i += 1;
+        }
+        // half full
+
+        let new_raw_cap = m.raw_capacity();
+        assert_eq!(new_raw_cap, raw_cap * 2);
+
+        for _ in 0..raw_cap / 2 - 1 {
+            i -= 1;
+            m.remove(&i);
+            assert_eq!(m.raw_capacity(), new_raw_cap);
+        }
+        // A little more than one quarter full.
+        m.shrink_to_fit();
+        assert_eq!(m.raw_capacity(), raw_cap);
+        // again, a little more than half full
+        for _ in 0..raw_cap / 2 {
+            i -= 1;
+            m.remove(&i);
+        }
+        m.shrink_to_fit();
+
+        assert_eq!(m.len(), i);
+        assert!(!m.is_empty());
+        assert_eq!(m.raw_capacity(), initial_raw_cap);
+    }
+
+    #[test]
+    fn test_reserve_shrink_to_fit() {
+        let mut m = HashMap::new();
+        m.insert(0, 0);
+        m.remove(&0);
+        assert!(m.capacity() >= m.len());
+        for i in 0..128 {
+            m.insert(i, i);
+        }
+        m.reserve(256);
+
+        let usable_cap = m.capacity();
+        for i in 128..(128 + 256) {
+            m.insert(i, i);
+            assert_eq!(m.capacity(), usable_cap);
+        }
+
+        for i in 100..(128 + 256) {
+            assert_eq!(m.remove(&i), Some(i));
+        }
+        m.shrink_to_fit();
+
+        assert_eq!(m.len(), 100);
+        assert!(!m.is_empty());
+        assert!(m.capacity() >= m.len());
+
+        for i in 0..100 {
+            assert_eq!(m.remove(&i), Some(i));
+        }
+        m.shrink_to_fit();
+        m.insert(0, 0);
+
+        assert_eq!(m.len(), 1);
+        assert!(m.capacity() >= m.len());
+        assert_eq!(m.remove(&0), Some(0));
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [(1, 1), (2, 2), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.iter().copied().collect();
+
+        for &(k, v) in &xs {
+            assert_eq!(map.get(&k), Some(&v));
+        }
+
+        assert_eq!(map.iter().len(), xs.len() - 1);
+    }
+
+    #[test]
+    fn test_size_hint() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.iter().copied().collect();
+
+        let mut iter = map.iter();
+
+        for _ in iter.by_ref().take(3) {}
+
+        assert_eq!(iter.size_hint(), (3, Some(3)));
+    }
+
+    #[test]
+    fn test_iter_len() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.iter().copied().collect();
+
+        let mut iter = map.iter();
+
+        for _ in iter.by_ref().take(3) {}
+
+        assert_eq!(iter.len(), 3);
+    }
+
+    #[test]
+    fn test_mut_size_hint() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let mut map: HashMap<_, _> = xs.iter().copied().collect();
+
+        let mut iter = map.iter_mut();
+
+        for _ in iter.by_ref().take(3) {}
+
+        assert_eq!(iter.size_hint(), (3, Some(3)));
+    }
+
+    #[test]
+    fn test_iter_mut_len() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let mut map: HashMap<_, _> = xs.iter().copied().collect();
+
+        let mut iter = map.iter_mut();
+
+        for _ in iter.by_ref().take(3) {}
+
+        assert_eq!(iter.len(), 3);
+    }
+
+    #[test]
+    fn test_index() {
+        let mut map = HashMap::new();
+
+        map.insert(1, 2);
+        map.insert(2, 1);
+        map.insert(3, 4);
+
+        assert_eq!(map[&2], 1);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_index_nonexistent() {
+        let mut map = HashMap::new();
+
+        map.insert(1, 2);
+        map.insert(2, 1);
+        map.insert(3, 4);
+
+        #[allow(clippy::no_effect)] // false positive lint
+        map[&4];
+    }
+
+    #[test]
+    fn test_entry() {
+        let xs = [(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
+
+        let mut map: HashMap<_, _> = xs.iter().copied().collect();
+
+        // Existing key (insert)
+        match map.entry(1) {
+            Vacant(_) => unreachable!(),
+            Occupied(mut view) => {
+                assert_eq!(view.get(), &10);
+                assert_eq!(view.insert(100), 10);
+            }
+        }
+        assert_eq!(map.get(&1).unwrap(), &100);
+        assert_eq!(map.len(), 6);
+
+        // Existing key (update)
+        match map.entry(2) {
+            Vacant(_) => unreachable!(),
+            Occupied(mut view) => {
+                let v = view.get_mut();
+                let new_v = (*v) * 10;
+                *v = new_v;
+            }
+        }
+        assert_eq!(map.get(&2).unwrap(), &200);
+        assert_eq!(map.len(), 6);
+
+        // Existing key (take)
+        match map.entry(3) {
+            Vacant(_) => unreachable!(),
+            Occupied(view) => {
+                assert_eq!(view.remove(), 30);
+            }
+        }
+        assert_eq!(map.get(&3), None);
+        assert_eq!(map.len(), 5);
+
+        // Inexistent key (insert)
+        match map.entry(10) {
+            Occupied(_) => unreachable!(),
+            Vacant(view) => {
+                assert_eq!(*view.insert(1000), 1000);
+            }
+        }
+        assert_eq!(map.get(&10).unwrap(), &1000);
+        assert_eq!(map.len(), 6);
+    }
+
+    #[test]
+    fn test_entry_ref() {
+        let xs = [
+            ("One".to_owned(), 10),
+            ("Two".to_owned(), 20),
+            ("Three".to_owned(), 30),
+            ("Four".to_owned(), 40),
+            ("Five".to_owned(), 50),
+            ("Six".to_owned(), 60),
+        ];
+
+        let mut map: HashMap<_, _> = xs.iter().cloned().collect();
+
+        // Existing key (insert)
+        match map.entry_ref("One") {
+            EntryRef::Vacant(_) => unreachable!(),
+            EntryRef::Occupied(mut view) => {
+                assert_eq!(view.get(), &10);
+                assert_eq!(view.insert(100), 10);
+            }
+        }
+        assert_eq!(map.get("One").unwrap(), &100);
+        assert_eq!(map.len(), 6);
+
+        // Existing key (update)
+        match map.entry_ref("Two") {
+            EntryRef::Vacant(_) => unreachable!(),
+            EntryRef::Occupied(mut view) => {
+                let v = view.get_mut();
+                let new_v = (*v) * 10;
+                *v = new_v;
+            }
+        }
+        assert_eq!(map.get("Two").unwrap(), &200);
+        assert_eq!(map.len(), 6);
+
+        // Existing key (take)
+        match map.entry_ref("Three") {
+            EntryRef::Vacant(_) => unreachable!(),
+            EntryRef::Occupied(view) => {
+                assert_eq!(view.remove(), 30);
+            }
+        }
+        assert_eq!(map.get("Three"), None);
+        assert_eq!(map.len(), 5);
+
+        // Inexistent key (insert)
+        match map.entry_ref("Ten") {
+            EntryRef::Occupied(_) => unreachable!(),
+            EntryRef::Vacant(view) => {
+                assert_eq!(*view.insert(1000), 1000);
+            }
+        }
+        assert_eq!(map.get("Ten").unwrap(), &1000);
+        assert_eq!(map.len(), 6);
+    }
+
+    #[test]
+    fn test_entry_take_doesnt_corrupt() {
+        #![allow(deprecated)] //rand
+                              // Test for #19292
+        fn check(m: &HashMap<i32, ()>) {
+            for k in m.keys() {
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
+            }
+        }
+
+        let mut m = HashMap::new();
+
+        let mut rng = {
+            let seed = u64::from_le_bytes(*b"testseed");
+            SmallRng::seed_from_u64(seed)
+        };
+
+        // Populate the map with some items.
+        for _ in 0..50 {
+            let x = rng.gen_range(-10..10);
+            m.insert(x, ());
+        }
+
+        for _ in 0..1000 {
+            let x = rng.gen_range(-10..10);
+            match m.entry(x) {
+                Vacant(_) => {}
+                Occupied(e) => {
+                    e.remove();
+                }
+            }
+
+            check(&m);
+        }
+    }
+
+    #[test]
+    fn test_entry_ref_take_doesnt_corrupt() {
+        #![allow(deprecated)] //rand
+                              // Test for #19292
+        fn check(m: &HashMap<std::string::String, ()>) {
+            for k in m.keys() {
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
+            }
+        }
+
+        let mut m = HashMap::new();
+
+        let mut rng = {
+            let seed = u64::from_le_bytes(*b"testseed");
+            SmallRng::seed_from_u64(seed)
+        };
+
+        // Populate the map with some items.
+        for _ in 0..50 {
+            let mut x = std::string::String::with_capacity(1);
+            x.push(rng.gen_range('a'..='z'));
+            m.insert(x, ());
+        }
+
+        for _ in 0..1000 {
+            let mut x = std::string::String::with_capacity(1);
+            x.push(rng.gen_range('a'..='z'));
+            match m.entry_ref(x.as_str()) {
+                EntryRef::Vacant(_) => {}
+                EntryRef::Occupied(e) => {
+                    e.remove();
+                }
+            }
+
+            check(&m);
+        }
+    }
+
+    #[test]
+    fn test_extend_ref_k_ref_v() {
+        let mut a = HashMap::new();
+        a.insert(1, "one");
+        let mut b = HashMap::new();
+        b.insert(2, "two");
+        b.insert(3, "three");
+
+        a.extend(&b);
+
+        assert_eq!(a.len(), 3);
+        assert_eq!(a[&1], "one");
+        assert_eq!(a[&2], "two");
+        assert_eq!(a[&3], "three");
+    }
+
+    #[test]
+    #[allow(clippy::needless_borrow)]
+    fn test_extend_ref_kv_tuple() {
+        use std::ops::AddAssign;
+        let mut a = HashMap::new();
+        a.insert(0, 0);
+
+        fn create_arr<T: AddAssign<T> + Copy, const N: usize>(start: T, step: T) -> [(T, T); N] {
+            let mut outs: [(T, T); N] = [(start, start); N];
+            let mut element = step;
+            outs.iter_mut().skip(1).for_each(|(k, v)| {
+                *k += element;
+                *v += element;
+                element += step;
+            });
+            outs
+        }
+
+        let for_iter: Vec<_> = (0..100).map(|i| (i, i)).collect();
+        let iter = for_iter.iter();
+        let vec: Vec<_> = (100..200).map(|i| (i, i)).collect();
+        a.extend(iter);
+        a.extend(&vec);
+        a.extend(create_arr::<i32, 100>(200, 1));
+
+        assert_eq!(a.len(), 300);
+
+        for item in 0..300 {
+            assert_eq!(a[&item], item);
+        }
+    }
+
+    #[test]
+    fn test_capacity_not_less_than_len() {
+        let mut a = HashMap::new();
+        let mut item = 0;
+
+        for _ in 0..116 {
+            a.insert(item, 0);
+            item += 1;
+        }
+
+        assert!(a.capacity() > a.len());
+
+        let free = a.capacity() - a.len();
+        for _ in 0..free {
+            a.insert(item, 0);
+            item += 1;
+        }
+
+        assert_eq!(a.len(), a.capacity());
+
+        // Insert at capacity should cause allocation.
+        a.insert(item, 0);
+        assert!(a.capacity() > a.len());
+    }
+
+    #[test]
+    fn test_occupied_entry_key() {
+        let mut a = HashMap::new();
+        let key = "hello there";
+        let value = "value goes here";
+        assert!(a.is_empty());
+        a.insert(key, value);
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+
+        match a.entry(key) {
+            Vacant(_) => panic!(),
+            Occupied(e) => assert_eq!(key, *e.key()),
+        }
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+    }
+
+    #[test]
+    fn test_occupied_entry_ref_key() {
+        let mut a = HashMap::new();
+        let key = "hello there";
+        let value = "value goes here";
+        assert!(a.is_empty());
+        a.insert(key.to_owned(), value);
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+
+        match a.entry_ref(key) {
+            EntryRef::Vacant(_) => panic!(),
+            EntryRef::Occupied(e) => assert_eq!(key, e.key()),
+        }
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+    }
+
+    #[test]
+    fn test_vacant_entry_key() {
+        let mut a = HashMap::new();
+        let key = "hello there";
+        let value = "value goes here";
+
+        assert!(a.is_empty());
+        match a.entry(key) {
+            Occupied(_) => panic!(),
+            Vacant(e) => {
+                assert_eq!(key, *e.key());
+                e.insert(value);
+            }
+        }
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+    }
+
+    #[test]
+    fn test_vacant_entry_ref_key() {
+        let mut a: HashMap<std::string::String, &str> = HashMap::new();
+        let key = "hello there";
+        let value = "value goes here";
+
+        assert!(a.is_empty());
+        match a.entry_ref(key) {
+            EntryRef::Occupied(_) => panic!(),
+            EntryRef::Vacant(e) => {
+                assert_eq!(key, e.key());
+                e.insert(value);
+            }
+        }
+        assert_eq!(a.len(), 1);
+        assert_eq!(a[key], value);
+    }
+
+    #[test]
+    fn test_occupied_entry_replace_entry_with() {
+        let mut a = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a.entry(key).insert(value).replace_entry_with(|k, v| {
+            assert_eq!(k, &key);
+            assert_eq!(v, value);
+            Some(new_value)
+        });
+
+        match entry {
+            Occupied(e) => {
+                assert_eq!(e.key(), &key);
+                assert_eq!(e.get(), &new_value);
+            }
+            Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = match a.entry(key) {
+            Occupied(e) => e.replace_entry_with(|k, v| {
+                assert_eq!(k, &key);
+                assert_eq!(v, new_value);
+                None
+            }),
+            Vacant(_) => panic!(),
+        };
+
+        match entry {
+            Vacant(e) => assert_eq!(e.key(), &key),
+            Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_occupied_entry_ref_replace_entry_with() {
+        let mut a: HashMap<std::string::String, &str> = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a.entry_ref(key).insert(value).replace_entry_with(|k, v| {
+            assert_eq!(k, key);
+            assert_eq!(v, value);
+            Some(new_value)
+        });
+
+        match entry {
+            EntryRef::Occupied(e) => {
+                assert_eq!(e.key(), key);
+                assert_eq!(e.get(), &new_value);
+            }
+            EntryRef::Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = match a.entry_ref(key) {
+            EntryRef::Occupied(e) => e.replace_entry_with(|k, v| {
+                assert_eq!(k, key);
+                assert_eq!(v, new_value);
+                None
+            }),
+            EntryRef::Vacant(_) => panic!(),
+        };
+
+        match entry {
+            EntryRef::Vacant(e) => assert_eq!(e.key(), key),
+            EntryRef::Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_entry_and_replace_entry_with() {
+        let mut a = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a.entry(key).and_replace_entry_with(|_, _| panic!());
+
+        match entry {
+            Vacant(e) => assert_eq!(e.key(), &key),
+            Occupied(_) => panic!(),
+        }
+
+        a.insert(key, value);
+
+        let entry = a.entry(key).and_replace_entry_with(|k, v| {
+            assert_eq!(k, &key);
+            assert_eq!(v, value);
+            Some(new_value)
+        });
+
+        match entry {
+            Occupied(e) => {
+                assert_eq!(e.key(), &key);
+                assert_eq!(e.get(), &new_value);
+            }
+            Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = a.entry(key).and_replace_entry_with(|k, v| {
+            assert_eq!(k, &key);
+            assert_eq!(v, new_value);
+            None
+        });
+
+        match entry {
+            Vacant(e) => assert_eq!(e.key(), &key),
+            Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_entry_ref_and_replace_entry_with() {
+        let mut a = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a.entry_ref(key).and_replace_entry_with(|_, _| panic!());
+
+        match entry {
+            EntryRef::Vacant(e) => assert_eq!(e.key(), key),
+            EntryRef::Occupied(_) => panic!(),
+        }
+
+        a.insert(key.to_owned(), value);
+
+        let entry = a.entry_ref(key).and_replace_entry_with(|k, v| {
+            assert_eq!(k, key);
+            assert_eq!(v, value);
+            Some(new_value)
+        });
+
+        match entry {
+            EntryRef::Occupied(e) => {
+                assert_eq!(e.key(), key);
+                assert_eq!(e.get(), &new_value);
+            }
+            EntryRef::Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = a.entry_ref(key).and_replace_entry_with(|k, v| {
+            assert_eq!(k, key);
+            assert_eq!(v, new_value);
+            None
+        });
+
+        match entry {
+            EntryRef::Vacant(e) => assert_eq!(e.key(), key),
+            EntryRef::Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_raw_occupied_entry_replace_entry_with() {
+        let mut a = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a
+            .raw_entry_mut()
+            .from_key(&key)
+            .insert(key, value)
+            .replace_entry_with(|k, v| {
+                assert_eq!(k, &key);
+                assert_eq!(v, value);
+                Some(new_value)
+            });
+
+        match entry {
+            RawEntryMut::Occupied(e) => {
+                assert_eq!(e.key(), &key);
+                assert_eq!(e.get(), &new_value);
+            }
+            RawEntryMut::Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = match a.raw_entry_mut().from_key(&key) {
+            RawEntryMut::Occupied(e) => e.replace_entry_with(|k, v| {
+                assert_eq!(k, &key);
+                assert_eq!(v, new_value);
+                None
+            }),
+            RawEntryMut::Vacant(_) => panic!(),
+        };
+
+        match entry {
+            RawEntryMut::Vacant(_) => {}
+            RawEntryMut::Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_raw_entry_and_replace_entry_with() {
+        let mut a = HashMap::new();
+
+        let key = "a key";
+        let value = "an initial value";
+        let new_value = "a new value";
+
+        let entry = a
+            .raw_entry_mut()
+            .from_key(&key)
+            .and_replace_entry_with(|_, _| panic!());
+
+        match entry {
+            RawEntryMut::Vacant(_) => {}
+            RawEntryMut::Occupied(_) => panic!(),
+        }
+
+        a.insert(key, value);
+
+        let entry = a
+            .raw_entry_mut()
+            .from_key(&key)
+            .and_replace_entry_with(|k, v| {
+                assert_eq!(k, &key);
+                assert_eq!(v, value);
+                Some(new_value)
+            });
+
+        match entry {
+            RawEntryMut::Occupied(e) => {
+                assert_eq!(e.key(), &key);
+                assert_eq!(e.get(), &new_value);
+            }
+            RawEntryMut::Vacant(_) => panic!(),
+        }
+
+        assert_eq!(a[key], new_value);
+        assert_eq!(a.len(), 1);
+
+        let entry = a
+            .raw_entry_mut()
+            .from_key(&key)
+            .and_replace_entry_with(|k, v| {
+                assert_eq!(k, &key);
+                assert_eq!(v, new_value);
+                None
+            });
+
+        match entry {
+            RawEntryMut::Vacant(_) => {}
+            RawEntryMut::Occupied(_) => panic!(),
+        }
+
+        assert!(!a.contains_key(key));
+        assert_eq!(a.len(), 0);
+    }
+
+    #[test]
+    fn test_replace_entry_with_doesnt_corrupt() {
+        #![allow(deprecated)] //rand
+                              // Test for #19292
+        fn check(m: &HashMap<i32, ()>) {
+            for k in m.keys() {
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
+            }
+        }
+
+        let mut m = HashMap::new();
+
+        let mut rng = {
+            let seed = u64::from_le_bytes(*b"testseed");
+            SmallRng::seed_from_u64(seed)
+        };
+
+        // Populate the map with some items.
+        for _ in 0..50 {
+            let x = rng.gen_range(-10..10);
+            m.insert(x, ());
+        }
+
+        for _ in 0..1000 {
+            let x = rng.gen_range(-10..10);
+            m.entry(x).and_replace_entry_with(|_, _| None);
+            check(&m);
+        }
+    }
+
+    #[test]
+    fn test_replace_entry_ref_with_doesnt_corrupt() {
+        #![allow(deprecated)] //rand
+                              // Test for #19292
+        fn check(m: &HashMap<std::string::String, ()>) {
+            for k in m.keys() {
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
+            }
+        }
+
+        let mut m = HashMap::new();
+
+        let mut rng = {
+            let seed = u64::from_le_bytes(*b"testseed");
+            SmallRng::seed_from_u64(seed)
+        };
+
+        // Populate the map with some items.
+        for _ in 0..50 {
+            let mut x = std::string::String::with_capacity(1);
+            x.push(rng.gen_range('a'..='z'));
+            m.insert(x, ());
+        }
+
+        for _ in 0..1000 {
+            let mut x = std::string::String::with_capacity(1);
+            x.push(rng.gen_range('a'..='z'));
+            m.entry_ref(x.as_str()).and_replace_entry_with(|_, _| None);
+            check(&m);
+        }
+    }
+
+    #[test]
+    fn test_retain() {
+        let mut map: HashMap<i32, i32> = (0..100).map(|x| (x, x * 10)).collect();
+
+        map.retain(|&k, _| k % 2 == 0);
+        assert_eq!(map.len(), 50);
+        assert_eq!(map[&2], 20);
+        assert_eq!(map[&4], 40);
+        assert_eq!(map[&6], 60);
+    }
+
+    #[test]
+    fn test_extract_if() {
+        {
+            let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x * 10)).collect();
+            let drained = map.extract_if(|&k, _| k % 2 == 0);
+            let mut out = drained.collect::<Vec<_>>();
+            out.sort_unstable();
+            assert_eq!(vec![(0, 0), (2, 20), (4, 40), (6, 60)], out);
+            assert_eq!(map.len(), 4);
+        }
+        {
+            let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x * 10)).collect();
+            map.extract_if(|&k, _| k % 2 == 0).for_each(drop);
+            assert_eq!(map.len(), 4);
+        }
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)] // FIXME: no OOM signalling (https://github.com/rust-lang/miri/issues/613)
+    fn test_try_reserve() {
+        use crate::TryReserveError::{AllocError, CapacityOverflow};
+
+        const MAX_ISIZE: usize = isize::MAX as usize;
+
+        let mut empty_bytes: HashMap<u8, u8> = HashMap::new();
+
+        if let Err(CapacityOverflow) = empty_bytes.try_reserve(usize::MAX) {
+        } else {
+            panic!("usize::MAX should trigger an overflow!");
+        }
+
+        if let Err(CapacityOverflow) = empty_bytes.try_reserve(MAX_ISIZE) {
+        } else {
+            panic!("isize::MAX should trigger an overflow!");
+        }
+
+        if let Err(AllocError { .. }) = empty_bytes.try_reserve(MAX_ISIZE / 5) {
+        } else {
+            // This may succeed if there is enough free memory. Attempt to
+            // allocate a few more hashmaps to ensure the allocation will fail.
+            let mut empty_bytes2: HashMap<u8, u8> = HashMap::new();
+            let _ = empty_bytes2.try_reserve(MAX_ISIZE / 5);
+            let mut empty_bytes3: HashMap<u8, u8> = HashMap::new();
+            let _ = empty_bytes3.try_reserve(MAX_ISIZE / 5);
+            let mut empty_bytes4: HashMap<u8, u8> = HashMap::new();
+            if let Err(AllocError { .. }) = empty_bytes4.try_reserve(MAX_ISIZE / 5) {
+            } else {
+                panic!("isize::MAX / 5 should trigger an OOM!");
+            }
+        }
+    }
+
+    #[test]
+    fn test_raw_entry() {
+        use super::RawEntryMut::{Occupied, Vacant};
+
+        let xs = [(1_i32, 10_i32), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
+
+        let mut map: HashMap<_, _> = xs.iter().copied().collect();
+
+        let compute_hash = |map: &HashMap<i32, i32>, k: i32| -> u64 {
+            super::make_hash::<i32, _>(map.hasher(), &k)
+        };
+
+        // Existing key (insert)
+        match map.raw_entry_mut().from_key(&1) {
+            Vacant(_) => unreachable!(),
+            Occupied(mut view) => {
+                assert_eq!(view.get(), &10);
+                assert_eq!(view.insert(100), 10);
+            }
+        }
+        let hash1 = compute_hash(&map, 1);
+        assert_eq!(map.raw_entry().from_key(&1).unwrap(), (&1, &100));
+        assert_eq!(
+            map.raw_entry().from_hash(hash1, |k| *k == 1).unwrap(),
+            (&1, &100)
+        );
+        assert_eq!(
+            map.raw_entry().from_key_hashed_nocheck(hash1, &1).unwrap(),
+            (&1, &100)
+        );
+        assert_eq!(map.len(), 6);
+
+        // Existing key (update)
+        match map.raw_entry_mut().from_key(&2) {
+            Vacant(_) => unreachable!(),
+            Occupied(mut view) => {
+                let v = view.get_mut();
+                let new_v = (*v) * 10;
+                *v = new_v;
+            }
+        }
+        let hash2 = compute_hash(&map, 2);
+        assert_eq!(map.raw_entry().from_key(&2).unwrap(), (&2, &200));
+        assert_eq!(
+            map.raw_entry().from_hash(hash2, |k| *k == 2).unwrap(),
+            (&2, &200)
+        );
+        assert_eq!(
+            map.raw_entry().from_key_hashed_nocheck(hash2, &2).unwrap(),
+            (&2, &200)
+        );
+        assert_eq!(map.len(), 6);
+
+        // Existing key (take)
+        let hash3 = compute_hash(&map, 3);
+        match map.raw_entry_mut().from_key_hashed_nocheck(hash3, &3) {
+            Vacant(_) => unreachable!(),
+            Occupied(view) => {
+                assert_eq!(view.remove_entry(), (3, 30));
+            }
+        }
+        assert_eq!(map.raw_entry().from_key(&3), None);
+        assert_eq!(map.raw_entry().from_hash(hash3, |k| *k == 3), None);
+        assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash3, &3), None);
+        assert_eq!(map.len(), 5);
+
+        // Nonexistent key (insert)
+        match map.raw_entry_mut().from_key(&10) {
+            Occupied(_) => unreachable!(),
+            Vacant(view) => {
+                assert_eq!(view.insert(10, 1000), (&mut 10, &mut 1000));
+            }
+        }
+        assert_eq!(map.raw_entry().from_key(&10).unwrap(), (&10, &1000));
+        assert_eq!(map.len(), 6);
+
+        // Ensure all lookup methods produce equivalent results.
+        for k in 0..12 {
+            let hash = compute_hash(&map, k);
+            let v = map.get(&k).copied();
+            let kv = v.as_ref().map(|v| (&k, v));
+
+            assert_eq!(map.raw_entry().from_key(&k), kv);
+            assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
+            assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
+
+            match map.raw_entry_mut().from_key(&k) {
+                Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
+                Vacant(_) => assert_eq!(v, None),
+            }
+            match map.raw_entry_mut().from_key_hashed_nocheck(hash, &k) {
+                Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
+                Vacant(_) => assert_eq!(v, None),
+            }
+            match map.raw_entry_mut().from_hash(hash, |q| *q == k) {
+                Occupied(o) => assert_eq!(Some(o.get_key_value()), kv),
+                Vacant(_) => assert_eq!(v, None),
+            }
+        }
+    }
+
+    #[test]
+    fn test_key_without_hash_impl() {
+        #[derive(Debug)]
+        struct IntWrapper(u64);
+
+        let mut m: HashMap<IntWrapper, (), ()> = HashMap::default();
+        {
+            assert!(m.raw_entry().from_hash(0, |k| k.0 == 0).is_none());
+        }
+        {
+            let vacant_entry = match m.raw_entry_mut().from_hash(0, |k| k.0 == 0) {
+                RawEntryMut::Occupied(..) => panic!("Found entry for key 0"),
+                RawEntryMut::Vacant(e) => e,
+            };
+            vacant_entry.insert_with_hasher(0, IntWrapper(0), (), |k| k.0);
+        }
+        {
+            assert!(m.raw_entry().from_hash(0, |k| k.0 == 0).is_some());
+            assert!(m.raw_entry().from_hash(1, |k| k.0 == 1).is_none());
+            assert!(m.raw_entry().from_hash(2, |k| k.0 == 2).is_none());
+        }
+        {
+            let vacant_entry = match m.raw_entry_mut().from_hash(1, |k| k.0 == 1) {
+                RawEntryMut::Occupied(..) => panic!("Found entry for key 1"),
+                RawEntryMut::Vacant(e) => e,
+            };
+            vacant_entry.insert_with_hasher(1, IntWrapper(1), (), |k| k.0);
+        }
+        {
+            assert!(m.raw_entry().from_hash(0, |k| k.0 == 0).is_some());
+            assert!(m.raw_entry().from_hash(1, |k| k.0 == 1).is_some());
+            assert!(m.raw_entry().from_hash(2, |k| k.0 == 2).is_none());
+        }
+        {
+            let occupied_entry = match m.raw_entry_mut().from_hash(0, |k| k.0 == 0) {
+                RawEntryMut::Occupied(e) => e,
+                RawEntryMut::Vacant(..) => panic!("Couldn't find entry for key 0"),
+            };
+            occupied_entry.remove();
+        }
+        assert!(m.raw_entry().from_hash(0, |k| k.0 == 0).is_none());
+        assert!(m.raw_entry().from_hash(1, |k| k.0 == 1).is_some());
+        assert!(m.raw_entry().from_hash(2, |k| k.0 == 2).is_none());
+    }
+
+    #[test]
+    #[cfg(feature = "raw")]
+    fn test_into_iter_refresh() {
+        #[cfg(miri)]
+        const N: usize = 32;
+        #[cfg(not(miri))]
+        const N: usize = 128;
+
+        let mut rng = rand::thread_rng();
+        for n in 0..N {
+            let mut map = HashMap::new();
+            for i in 0..n {
+                assert!(map.insert(i, 2 * i).is_none());
+            }
+            let hash_builder = map.hasher().clone();
+
+            let mut it = unsafe { map.table.iter() };
+            assert_eq!(it.len(), n);
+
+            let mut i = 0;
+            let mut left = n;
+            let mut removed = Vec::new();
+            loop {
+                // occasionally remove some elements
+                if i < n && rng.gen_bool(0.1) {
+                    let hash_value = super::make_hash(&hash_builder, &i);
+
+                    unsafe {
+                        let e = map.table.find(hash_value, |q| q.0.eq(&i));
+                        if let Some(e) = e {
+                            it.reflect_remove(&e);
+                            let t = map.table.remove(e).0;
+                            removed.push(t);
+                            left -= 1;
+                        } else {
+                            assert!(removed.contains(&(i, 2 * i)), "{i} not in {removed:?}");
+                            let e = map.table.insert(
+                                hash_value,
+                                (i, 2 * i),
+                                super::make_hasher::<_, usize, _>(&hash_builder),
+                            );
+                            it.reflect_insert(&e);
+                            if let Some(p) = removed.iter().position(|e| e == &(i, 2 * i)) {
+                                removed.swap_remove(p);
+                            }
+                            left += 1;
+                        }
+                    }
+                }
+
+                let e = it.next();
+                if e.is_none() {
+                    break;
+                }
+                assert!(i < n);
+                let t = unsafe { e.unwrap().as_ref() };
+                assert!(!removed.contains(t));
+                let (key, value) = t;
+                assert_eq!(*value, 2 * key);
+                i += 1;
+            }
+            assert!(i <= n);
+
+            // just for safety:
+            assert_eq!(map.table.len(), left);
+        }
+    }
+
+    #[test]
+    fn test_const_with_hasher() {
+        use core::hash::BuildHasher;
+        use std::collections::hash_map::DefaultHasher;
+
+        #[derive(Clone)]
+        struct MyHasher;
+        impl BuildHasher for MyHasher {
+            type Hasher = DefaultHasher;
+
+            fn build_hasher(&self) -> DefaultHasher {
+                DefaultHasher::new()
+            }
+        }
+
+        const EMPTY_MAP: HashMap<u32, std::string::String, MyHasher> =
+            HashMap::with_hasher(MyHasher);
+
+        let mut map = EMPTY_MAP;
+        map.insert(17, "seventeen".to_owned());
+        assert_eq!("seventeen", map[&17]);
+    }
+
+    #[test]
+    fn test_get_each_mut() {
+        let mut map = HashMap::new();
+        map.insert("foo".to_owned(), 0);
+        map.insert("bar".to_owned(), 10);
+        map.insert("baz".to_owned(), 20);
+        map.insert("qux".to_owned(), 30);
+
+        let xs = map.get_many_mut(["foo", "qux"]);
+        assert_eq!(xs, Some([&mut 0, &mut 30]));
+
+        let xs = map.get_many_mut(["foo", "dud"]);
+        assert_eq!(xs, None);
+
+        let xs = map.get_many_mut(["foo", "foo"]);
+        assert_eq!(xs, None);
+
+        let ys = map.get_many_key_value_mut(["bar", "baz"]);
+        assert_eq!(
+            ys,
+            Some([(&"bar".to_owned(), &mut 10), (&"baz".to_owned(), &mut 20),]),
+        );
+
+        let ys = map.get_many_key_value_mut(["bar", "dip"]);
+        assert_eq!(ys, None);
+
+        let ys = map.get_many_key_value_mut(["baz", "baz"]);
+        assert_eq!(ys, None);
+    }
+
+    #[test]
+    #[should_panic = "panic in drop"]
+    fn test_clone_from_double_drop() {
+        #[derive(Clone)]
+        struct CheckedDrop {
+            panic_in_drop: bool,
+            dropped: bool,
+        }
+        impl Drop for CheckedDrop {
+            fn drop(&mut self) {
+                if self.panic_in_drop {
+                    self.dropped = true;
+                    panic!("panic in drop");
+                }
+                if self.dropped {
+                    panic!("double drop");
+                }
+                self.dropped = true;
+            }
+        }
+        const DISARMED: CheckedDrop = CheckedDrop {
+            panic_in_drop: false,
+            dropped: false,
+        };
+        const ARMED: CheckedDrop = CheckedDrop {
+            panic_in_drop: true,
+            dropped: false,
+        };
+
+        let mut map1 = HashMap::new();
+        map1.insert(1, DISARMED);
+        map1.insert(2, DISARMED);
+        map1.insert(3, DISARMED);
+        map1.insert(4, DISARMED);
+
+        let mut map2 = HashMap::new();
+        map2.insert(1, DISARMED);
+        map2.insert(2, ARMED);
+        map2.insert(3, DISARMED);
+        map2.insert(4, DISARMED);
+
+        map2.clone_from(&map1);
+    }
+
+    #[test]
+    #[should_panic = "panic in clone"]
+    fn test_clone_from_memory_leaks() {
+        use ::alloc::vec::Vec;
+
+        struct CheckedClone {
+            panic_in_clone: bool,
+            need_drop: Vec<i32>,
+        }
+        impl Clone for CheckedClone {
+            fn clone(&self) -> Self {
+                if self.panic_in_clone {
+                    panic!("panic in clone")
+                }
+                Self {
+                    panic_in_clone: self.panic_in_clone,
+                    need_drop: self.need_drop.clone(),
+                }
+            }
+        }
+        let mut map1 = HashMap::new();
+        map1.insert(
+            1,
+            CheckedClone {
+                panic_in_clone: false,
+                need_drop: vec![0, 1, 2],
+            },
+        );
+        map1.insert(
+            2,
+            CheckedClone {
+                panic_in_clone: false,
+                need_drop: vec![3, 4, 5],
+            },
+        );
+        map1.insert(
+            3,
+            CheckedClone {
+                panic_in_clone: true,
+                need_drop: vec![6, 7, 8],
+            },
+        );
+        let _map2 = map1.clone();
+    }
+
+    struct MyAllocInner {
+        drop_count: Arc<AtomicI8>,
+    }
+
+    #[derive(Clone)]
+    struct MyAlloc {
+        _inner: Arc<MyAllocInner>,
+    }
+
+    impl MyAlloc {
+        fn new(drop_count: Arc<AtomicI8>) -> Self {
+            MyAlloc {
+                _inner: Arc::new(MyAllocInner { drop_count }),
+            }
+        }
+    }
+
+    impl Drop for MyAllocInner {
+        fn drop(&mut self) {
+            println!("MyAlloc freed.");
+            self.drop_count.fetch_sub(1, Ordering::SeqCst);
+        }
+    }
+
+    unsafe impl Allocator for MyAlloc {
+        fn allocate(&self, layout: Layout) -> std::result::Result<NonNull<[u8]>, AllocError> {
+            let g = Global;
+            g.allocate(layout)
+        }
+
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+            let g = Global;
+            g.deallocate(ptr, layout)
+        }
+    }
+
+    #[test]
+    fn test_hashmap_into_iter_bug() {
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(1));
+
+        {
+            let mut map = HashMap::with_capacity_in(10, MyAlloc::new(dropped.clone()));
+            for i in 0..10 {
+                map.entry(i).or_insert_with(|| "i".to_string());
+            }
+
+            for (k, v) in map {
+                println!("{}, {}", k, v);
+            }
+        }
+
+        // All allocator clones should already be dropped.
+        assert_eq!(dropped.load(Ordering::SeqCst), 0);
+    }
+
+    #[derive(Debug)]
+    struct CheckedCloneDrop<T> {
+        panic_in_clone: bool,
+        panic_in_drop: bool,
+        dropped: bool,
+        data: T,
+    }
+
+    impl<T> CheckedCloneDrop<T> {
+        fn new(panic_in_clone: bool, panic_in_drop: bool, data: T) -> Self {
+            CheckedCloneDrop {
+                panic_in_clone,
+                panic_in_drop,
+                dropped: false,
+                data,
+            }
+        }
+    }
+
+    impl<T: Clone> Clone for CheckedCloneDrop<T> {
+        fn clone(&self) -> Self {
+            if self.panic_in_clone {
+                panic!("panic in clone")
+            }
+            Self {
+                panic_in_clone: self.panic_in_clone,
+                panic_in_drop: self.panic_in_drop,
+                dropped: self.dropped,
+                data: self.data.clone(),
+            }
+        }
+    }
+
+    impl<T> Drop for CheckedCloneDrop<T> {
+        fn drop(&mut self) {
+            if self.panic_in_drop {
+                self.dropped = true;
+                panic!("panic in drop");
+            }
+            if self.dropped {
+                panic!("double drop");
+            }
+            self.dropped = true;
+        }
+    }
+
+    /// Return hashmap with predefined distribution of elements.
+    /// All elements will be located in the same order as elements
+    /// returned by iterator.
+    ///
+    /// This function does not panic, but returns an error as a `String`
+    /// to distinguish between a test panic and an error in the input data.
+    fn get_test_map<I, T, A>(
+        iter: I,
+        mut fun: impl FnMut(u64) -> T,
+        alloc: A,
+    ) -> Result<HashMap<u64, CheckedCloneDrop<T>, DefaultHashBuilder, A>, String>
+    where
+        I: Iterator<Item = (bool, bool)> + Clone + ExactSizeIterator,
+        A: Allocator,
+        T: PartialEq + core::fmt::Debug,
+    {
+        use crate::scopeguard::guard;
+
+        let mut map: HashMap<u64, CheckedCloneDrop<T>, _, A> =
+            HashMap::with_capacity_in(iter.size_hint().0, alloc);
+        {
+            let mut guard = guard(&mut map, |map| {
+                for (_, value) in map.iter_mut() {
+                    value.panic_in_drop = false
+                }
+            });
+
+            let mut count = 0;
+            // Hash and Key must be equal to each other for controlling the elements placement.
+            for (panic_in_clone, panic_in_drop) in iter.clone() {
+                if core::mem::needs_drop::<T>() && panic_in_drop {
+                    return Err(String::from(
+                        "panic_in_drop can be set with a type that doesn't need to be dropped",
+                    ));
+                }
+                guard.table.insert(
+                    count,
+                    (
+                        count,
+                        CheckedCloneDrop::new(panic_in_clone, panic_in_drop, fun(count)),
+                    ),
+                    |(k, _)| *k,
+                );
+                count += 1;
+            }
+
+            // Let's check that all elements are located as we wanted
+            let mut check_count = 0;
+            for ((key, value), (panic_in_clone, panic_in_drop)) in guard.iter().zip(iter) {
+                if *key != check_count {
+                    return Err(format!(
+                        "key != check_count,\nkey: `{}`,\ncheck_count: `{}`",
+                        key, check_count
+                    ));
+                }
+                if value.dropped
+                    || value.panic_in_clone != panic_in_clone
+                    || value.panic_in_drop != panic_in_drop
+                    || value.data != fun(check_count)
+                {
+                    return Err(format!(
+                        "Value is not equal to expected,\nvalue: `{:?}`,\nexpected: \
+                        `CheckedCloneDrop {{ panic_in_clone: {}, panic_in_drop: {}, dropped: {}, data: {:?} }}`",
+                        value, panic_in_clone, panic_in_drop, false, fun(check_count)
+                    ));
+                }
+                check_count += 1;
+            }
+
+            if guard.len() != check_count as usize {
+                return Err(format!(
+                    "map.len() != check_count,\nmap.len(): `{}`,\ncheck_count: `{}`",
+                    guard.len(),
+                    check_count
+                ));
+            }
+
+            if count != check_count {
+                return Err(format!(
+                    "count != check_count,\ncount: `{}`,\ncheck_count: `{}`",
+                    count, check_count
+                ));
+            }
+            core::mem::forget(guard);
+        }
+        Ok(map)
+    }
+
+    const DISARMED: bool = false;
+    const ARMED: bool = true;
+
+    const ARMED_FLAGS: [bool; 8] = [
+        DISARMED, DISARMED, DISARMED, ARMED, DISARMED, DISARMED, DISARMED, DISARMED,
+    ];
+
+    const DISARMED_FLAGS: [bool; 8] = [
+        DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED, DISARMED,
+    ];
+
+    #[test]
+    #[should_panic = "panic in clone"]
+    fn test_clone_memory_leaks_and_double_drop_one() {
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
+
+        {
+            assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
+
+            let map: HashMap<u64, CheckedCloneDrop<Vec<u64>>, DefaultHashBuilder, MyAlloc> =
+                match get_test_map(
+                    ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
+                    |n| vec![n],
+                    MyAlloc::new(dropped.clone()),
+                ) {
+                    Ok(map) => map,
+                    Err(msg) => panic!("{msg}"),
+                };
+
+            // Clone should normally clone a few elements, and then (when the
+            // clone function panics), deallocate both its own memory, memory
+            // of `dropped: Arc<AtomicI8>` and the memory of already cloned
+            // elements (Vec<i32> memory inside CheckedCloneDrop).
+            let _map2 = map.clone();
+        }
+    }
+
+    #[test]
+    #[should_panic = "panic in drop"]
+    fn test_clone_memory_leaks_and_double_drop_two() {
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
+
+        {
+            assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
+
+            let map: HashMap<u64, CheckedCloneDrop<u64>, DefaultHashBuilder, _> = match get_test_map(
+                DISARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
+                |n| n,
+                MyAlloc::new(dropped.clone()),
+            ) {
+                Ok(map) => map,
+                Err(msg) => panic!("{msg}"),
+            };
+
+            let mut map2 = match get_test_map(
+                DISARMED_FLAGS.into_iter().zip(ARMED_FLAGS),
+                |n| n,
+                MyAlloc::new(dropped.clone()),
+            ) {
+                Ok(map) => map,
+                Err(msg) => panic!("{msg}"),
+            };
+
+            // The `clone_from` should try to drop the elements of `map2` without
+            // double drop and leaking the allocator. Elements that have not been
+            // dropped leak their memory.
+            map2.clone_from(&map);
+        }
+    }
+
+    /// We check that we have a working table if the clone operation from another
+    /// thread ended in a panic (when buckets of maps are equal to each other).
+    #[test]
+    fn test_catch_panic_clone_from_when_len_is_equal() {
+        use std::thread;
+
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
+
+        {
+            assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
+
+            let mut map = match get_test_map(
+                DISARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
+                |n| vec![n],
+                MyAlloc::new(dropped.clone()),
+            ) {
+                Ok(map) => map,
+                Err(msg) => panic!("{msg}"),
+            };
+
+            thread::scope(|s| {
+                let result: thread::ScopedJoinHandle<'_, String> = s.spawn(|| {
+                    let scope_map =
+                        match get_test_map(ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS), |n| vec![n * 2], MyAlloc::new(dropped.clone())) {
+                            Ok(map) => map,
+                            Err(msg) => return msg,
+                        };
+                    if map.table.buckets() != scope_map.table.buckets() {
+                        return format!(
+                            "map.table.buckets() != scope_map.table.buckets(),\nleft: `{}`,\nright: `{}`",
+                            map.table.buckets(), scope_map.table.buckets()
+                        );
+                    }
+                    map.clone_from(&scope_map);
+                    "We must fail the cloning!!!".to_owned()
+                });
+                if let Ok(msg) = result.join() {
+                    panic!("{msg}")
+                }
+            });
+
+            // Let's check that all iterators work fine and do not return elements
+            // (especially `RawIterRange`, which does not depend on the number of
+            // elements in the table, but looks directly at the control bytes)
+            //
+            // SAFETY: We know for sure that `RawTable` will outlive
+            // the returned `RawIter / RawIterRange` iterator.
+            assert_eq!(map.len(), 0);
+            assert_eq!(map.iter().count(), 0);
+            assert_eq!(unsafe { map.table.iter().count() }, 0);
+            assert_eq!(unsafe { map.table.iter().iter.count() }, 0);
+
+            for idx in 0..map.table.buckets() {
+                let idx = idx as u64;
+                assert!(
+                    map.table.find(idx, |(k, _)| *k == idx).is_none(),
+                    "Index: {idx}"
+                );
+            }
+        }
+
+        // All allocator clones should already be dropped.
+        assert_eq!(dropped.load(Ordering::SeqCst), 0);
+    }
+
+    /// We check that we have a working table if the clone operation from another
+    /// thread ended in a panic (when buckets of maps are not equal to each other).
+    #[test]
+    fn test_catch_panic_clone_from_when_len_is_not_equal() {
+        use std::thread;
+
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
+
+        {
+            assert_eq!(ARMED_FLAGS.len(), DISARMED_FLAGS.len());
+
+            let mut map = match get_test_map(
+                [DISARMED].into_iter().zip([DISARMED]),
+                |n| vec![n],
+                MyAlloc::new(dropped.clone()),
+            ) {
+                Ok(map) => map,
+                Err(msg) => panic!("{msg}"),
+            };
+
+            thread::scope(|s| {
+                let result: thread::ScopedJoinHandle<'_, String> = s.spawn(|| {
+                    let scope_map = match get_test_map(
+                        ARMED_FLAGS.into_iter().zip(DISARMED_FLAGS),
+                        |n| vec![n * 2],
+                        MyAlloc::new(dropped.clone()),
+                    ) {
+                        Ok(map) => map,
+                        Err(msg) => return msg,
+                    };
+                    if map.table.buckets() == scope_map.table.buckets() {
+                        return format!(
+                            "map.table.buckets() == scope_map.table.buckets(): `{}`",
+                            map.table.buckets()
+                        );
+                    }
+                    map.clone_from(&scope_map);
+                    "We must fail the cloning!!!".to_owned()
+                });
+                if let Ok(msg) = result.join() {
+                    panic!("{msg}")
+                }
+            });
+
+            // Let's check that all iterators work fine and do not return elements
+            // (especially `RawIterRange`, which does not depend on the number of
+            // elements in the table, but looks directly at the control bytes)
+            //
+            // SAFETY: We know for sure that `RawTable` will outlive
+            // the returned `RawIter / RawIterRange` iterator.
+            assert_eq!(map.len(), 0);
+            assert_eq!(map.iter().count(), 0);
+            assert_eq!(unsafe { map.table.iter().count() }, 0);
+            assert_eq!(unsafe { map.table.iter().iter.count() }, 0);
+
+            for idx in 0..map.table.buckets() {
+                let idx = idx as u64;
+                assert!(
+                    map.table.find(idx, |(k, _)| *k == idx).is_none(),
+                    "Index: {idx}"
+                );
+            }
+        }
+
+        // All allocator clones should already be dropped.
+        assert_eq!(dropped.load(Ordering::SeqCst), 0);
+    }
+}
diff --git a/vendor/hashbrown/src/raw/alloc.rs b/vendor/hashbrown/src/raw/alloc.rs
new file mode 100644
index 0000000..15299e7
--- /dev/null
+++ b/vendor/hashbrown/src/raw/alloc.rs
@@ -0,0 +1,86 @@
+pub(crate) use self::inner::{do_alloc, Allocator, Global};
+
+// Nightly-case.
+// Use unstable `allocator_api` feature.
+// This is compatible with `allocator-api2` which can be enabled or not.
+// This is used when building for `std`.
+#[cfg(feature = "nightly")]
+mod inner {
+    use crate::alloc::alloc::Layout;
+    pub use crate::alloc::alloc::{Allocator, Global};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::map_err_ignore)]
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
+        match alloc.allocate(layout) {
+            Ok(ptr) => Ok(ptr.as_non_null_ptr()),
+            Err(_) => Err(()),
+        }
+    }
+}
+
+// Basic non-nightly case.
+// This uses `allocator-api2` enabled by default.
+// If any crate enables "nightly" in `allocator-api2`,
+// this will be equivalent to the nightly case,
+// since `allocator_api2::alloc::Allocator` would be re-export of
+// `core::alloc::Allocator`.
+#[cfg(all(not(feature = "nightly"), feature = "allocator-api2"))]
+mod inner {
+    use crate::alloc::alloc::Layout;
+    pub use allocator_api2::alloc::{Allocator, Global};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::map_err_ignore)]
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
+        match alloc.allocate(layout) {
+            Ok(ptr) => Ok(ptr.cast()),
+            Err(_) => Err(()),
+        }
+    }
+}
+
+// No-defaults case.
+// When building with default-features turned off and
+// neither `nightly` nor `allocator-api2` is enabled,
+// this will be used.
+// Making it impossible to use any custom allocator with collections defined
+// in this crate.
+// Any crate in build-tree can enable `allocator-api2`,
+// or `nightly` without disturbing users that don't want to use it.
+#[cfg(not(any(feature = "nightly", feature = "allocator-api2")))]
+mod inner {
+    use crate::alloc::alloc::{alloc, dealloc, Layout};
+    use core::ptr::NonNull;
+
+    #[allow(clippy::missing_safety_doc)] // not exposed outside of this crate
+    pub unsafe trait Allocator {
+        fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()>;
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct Global;
+
+    unsafe impl Allocator for Global {
+        #[inline]
+        fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()> {
+            unsafe { NonNull::new(alloc(layout)).ok_or(()) }
+        }
+        #[inline]
+        unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+            dealloc(ptr.as_ptr(), layout);
+        }
+    }
+
+    impl Default for Global {
+        #[inline]
+        fn default() -> Self {
+            Global
+        }
+    }
+
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
+        alloc.allocate(layout)
+    }
+}
diff --git a/vendor/hashbrown/src/raw/bitmask.rs b/vendor/hashbrown/src/raw/bitmask.rs
new file mode 100644
index 0000000..6576b3c
--- /dev/null
+++ b/vendor/hashbrown/src/raw/bitmask.rs
@@ -0,0 +1,133 @@
+use super::imp::{
+    BitMaskWord, NonZeroBitMaskWord, BITMASK_ITER_MASK, BITMASK_MASK, BITMASK_STRIDE,
+};
+
+/// A bit mask which contains the result of a `Match` operation on a `Group` and
+/// allows iterating through them.
+///
+/// The bit mask is arranged so that low-order bits represent lower memory
+/// addresses for group match results.
+///
+/// For implementation reasons, the bits in the set may be sparsely packed with
+/// groups of 8 bits representing one element. If any of these bits are non-zero
+/// then this element is considered to true in the mask. If this is the
+/// case, `BITMASK_STRIDE` will be 8 to indicate a divide-by-8 should be
+/// performed on counts/indices to normalize this difference. `BITMASK_MASK` is
+/// similarly a mask of all the actually-used bits.
+///
+/// To iterate over a bit mask, it must be converted to a form where only 1 bit
+/// is set per element. This is done by applying `BITMASK_ITER_MASK` on the
+/// mask bits.
+#[derive(Copy, Clone)]
+pub(crate) struct BitMask(pub(crate) BitMaskWord);
+
+#[allow(clippy::use_self)]
+impl BitMask {
+    /// Returns a new `BitMask` with all bits inverted.
+    #[inline]
+    #[must_use]
+    #[allow(dead_code)]
+    pub(crate) fn invert(self) -> Self {
+        BitMask(self.0 ^ BITMASK_MASK)
+    }
+
+    /// Returns a new `BitMask` with the lowest bit removed.
+    #[inline]
+    #[must_use]
+    fn remove_lowest_bit(self) -> Self {
+        BitMask(self.0 & (self.0 - 1))
+    }
+
+    /// Returns whether the `BitMask` has at least one set bit.
+    #[inline]
+    pub(crate) fn any_bit_set(self) -> bool {
+        self.0 != 0
+    }
+
+    /// Returns the first set bit in the `BitMask`, if there is one.
+    #[inline]
+    pub(crate) fn lowest_set_bit(self) -> Option<usize> {
+        if let Some(nonzero) = NonZeroBitMaskWord::new(self.0) {
+            Some(Self::nonzero_trailing_zeros(nonzero))
+        } else {
+            None
+        }
+    }
+
+    /// Returns the number of trailing zeroes in the `BitMask`.
+    #[inline]
+    pub(crate) fn trailing_zeros(self) -> usize {
+        // ARM doesn't have a trailing_zeroes instruction, and instead uses
+        // reverse_bits (RBIT) + leading_zeroes (CLZ). However older ARM
+        // versions (pre-ARMv7) don't have RBIT and need to emulate it
+        // instead. Since we only have 1 bit set in each byte on ARM, we can
+        // use swap_bytes (REV) + leading_zeroes instead.
+        if cfg!(target_arch = "arm") && BITMASK_STRIDE % 8 == 0 {
+            self.0.swap_bytes().leading_zeros() as usize / BITMASK_STRIDE
+        } else {
+            self.0.trailing_zeros() as usize / BITMASK_STRIDE
+        }
+    }
+
+    /// Same as above but takes a `NonZeroBitMaskWord`.
+    #[inline]
+    fn nonzero_trailing_zeros(nonzero: NonZeroBitMaskWord) -> usize {
+        if cfg!(target_arch = "arm") && BITMASK_STRIDE % 8 == 0 {
+            // SAFETY: A byte-swapped non-zero value is still non-zero.
+            let swapped = unsafe { NonZeroBitMaskWord::new_unchecked(nonzero.get().swap_bytes()) };
+            swapped.leading_zeros() as usize / BITMASK_STRIDE
+        } else {
+            nonzero.trailing_zeros() as usize / BITMASK_STRIDE
+        }
+    }
+
+    /// Returns the number of leading zeroes in the `BitMask`.
+    #[inline]
+    pub(crate) fn leading_zeros(self) -> usize {
+        self.0.leading_zeros() as usize / BITMASK_STRIDE
+    }
+}
+
+impl IntoIterator for BitMask {
+    type Item = usize;
+    type IntoIter = BitMaskIter;
+
+    #[inline]
+    fn into_iter(self) -> BitMaskIter {
+        // A BitMask only requires each element (group of bits) to be non-zero.
+        // However for iteration we need each element to only contain 1 bit.
+        BitMaskIter(BitMask(self.0 & BITMASK_ITER_MASK))
+    }
+}
+
+/// Iterator over the contents of a `BitMask`, returning the indices of set
+/// bits.
+#[derive(Copy, Clone)]
+pub(crate) struct BitMaskIter(pub(crate) BitMask);
+
+impl BitMaskIter {
+    /// Flip the bit in the mask for the entry at the given index.
+    ///
+    /// Returns the bit's previous state.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    #[cfg(feature = "raw")]
+    pub(crate) unsafe fn flip(&mut self, index: usize) -> bool {
+        // NOTE: The + BITMASK_STRIDE - 1 is to set the high bit.
+        let mask = 1 << (index * BITMASK_STRIDE + BITMASK_STRIDE - 1);
+        self.0 .0 ^= mask;
+        // The bit was set if the bit is now 0.
+        self.0 .0 & mask == 0
+    }
+}
+
+impl Iterator for BitMaskIter {
+    type Item = usize;
+
+    #[inline]
+    fn next(&mut self) -> Option<usize> {
+        let bit = self.0.lowest_set_bit()?;
+        self.0 = self.0.remove_lowest_bit();
+        Some(bit)
+    }
+}
diff --git a/vendor/hashbrown/src/raw/generic.rs b/vendor/hashbrown/src/raw/generic.rs
new file mode 100644
index 0000000..c668b06
--- /dev/null
+++ b/vendor/hashbrown/src/raw/generic.rs
@@ -0,0 +1,157 @@
+use super::bitmask::BitMask;
+use super::EMPTY;
+use core::{mem, ptr};
+
+// Use the native word size as the group size. Using a 64-bit group size on
+// a 32-bit architecture will just end up being more expensive because
+// shifts and multiplies will need to be emulated.
+
+cfg_if! {
+    if #[cfg(any(
+        target_pointer_width = "64",
+        target_arch = "aarch64",
+        target_arch = "x86_64",
+        target_arch = "wasm32",
+    ))] {
+        type GroupWord = u64;
+        type NonZeroGroupWord = core::num::NonZeroU64;
+    } else {
+        type GroupWord = u32;
+        type NonZeroGroupWord = core::num::NonZeroU32;
+    }
+}
+
+pub(crate) type BitMaskWord = GroupWord;
+pub(crate) type NonZeroBitMaskWord = NonZeroGroupWord;
+pub(crate) const BITMASK_STRIDE: usize = 8;
+// We only care about the highest bit of each byte for the mask.
+#[allow(clippy::cast_possible_truncation, clippy::unnecessary_cast)]
+pub(crate) const BITMASK_MASK: BitMaskWord = 0x8080_8080_8080_8080_u64 as GroupWord;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
+
+/// Helper function to replicate a byte across a `GroupWord`.
+#[inline]
+fn repeat(byte: u8) -> GroupWord {
+    GroupWord::from_ne_bytes([byte; Group::WIDTH])
+}
+
+/// Abstraction over a group of control bytes which can be scanned in
+/// parallel.
+///
+/// This implementation uses a word-sized integer.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(GroupWord);
+
+// We perform all operations in the native endianness, and convert to
+// little-endian just before creating a BitMask. The can potentially
+// enable the compiler to eliminate unnecessary byte swaps if we are
+// only checking whether a BitMask is empty.
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty bytes, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    pub(crate) const fn static_empty() -> &'static [u8; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedBytes {
+            _align: [Group; 0],
+            bytes: [u8; Group::WIDTH],
+        }
+        const ALIGNED_BYTES: AlignedBytes = AlignedBytes {
+            _align: [],
+            bytes: [EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_BYTES.bytes
+    }
+
+    /// Loads a group of bytes starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
+        Group(ptr::read_unaligned(ptr.cast()))
+    }
+
+    /// Loads a group of bytes starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const u8) -> Self {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        Group(ptr::read(ptr.cast()))
+    }
+
+    /// Stores the group of bytes to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut u8) {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        ptr::write(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which *may*
+    /// have the given value.
+    ///
+    /// This function may return a false positive in certain cases where
+    /// the byte in the group differs from the searched value only in its
+    /// lowest bit. This is fine because:
+    /// - This never happens for `EMPTY` and `DELETED`, only full entries.
+    /// - The check for key equality will catch these.
+    /// - This only happens if there is at least 1 true match.
+    /// - The chance of this happening is very low (< 1% chance per byte).
+    #[inline]
+    pub(crate) fn match_byte(self, byte: u8) -> BitMask {
+        // This algorithm is derived from
+        // https://graphics.stanford.edu/~seander/bithacks.html##ValueInWord
+        let cmp = self.0 ^ repeat(byte);
+        BitMask((cmp.wrapping_sub(repeat(0x01)) & !cmp & repeat(0x80)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        // If the high bit is set, then the byte must be either:
+        // 1111_1111 (EMPTY) or 1000_0000 (DELETED).
+        // So we can just check if the top two bits are 1 by ANDing them.
+        BitMask((self.0 & (self.0 << 1) & repeat(0x80)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        // A byte is EMPTY or DELETED iff the high bit is set
+        BitMask((self.0 & repeat(0x80)).to_le())
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(self) -> BitMask {
+        self.match_empty_or_deleted().invert()
+    }
+
+    /// Performs the following transformation on all bytes in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let full = 1000_0000 (true) or 0000_0000 (false)
+        //   !1000_0000 + 1 = 0111_1111 + 1 = 1000_0000 (no carry)
+        //   !0000_0000 + 0 = 1111_1111 + 0 = 1111_1111 (no carry)
+        let full = !self.0 & repeat(0x80);
+        Group(!full + (full >> 7))
+    }
+}
diff --git a/vendor/hashbrown/src/raw/mod.rs b/vendor/hashbrown/src/raw/mod.rs
new file mode 100644
index 0000000..789c3a5
--- /dev/null
+++ b/vendor/hashbrown/src/raw/mod.rs
@@ -0,0 +1,4478 @@
+use crate::alloc::alloc::{handle_alloc_error, Layout};
+use crate::scopeguard::{guard, ScopeGuard};
+use crate::TryReserveError;
+use core::iter::FusedIterator;
+use core::marker::PhantomData;
+use core::mem;
+use core::mem::MaybeUninit;
+use core::ptr::NonNull;
+use core::{hint, ptr};
+
+cfg_if! {
+    // Use the SSE2 implementation if possible: it allows us to scan 16 buckets
+    // at once instead of 8. We don't bother with AVX since it would require
+    // runtime dispatch and wouldn't gain us much anyways: the probability of
+    // finding a match drops off drastically after the first few buckets.
+    //
+    // I attempted an implementation on ARM using NEON instructions, but it
+    // turns out that most NEON instructions have multi-cycle latency, which in
+    // the end outweighs any gains over the generic implementation.
+    if #[cfg(all(
+        target_feature = "sse2",
+        any(target_arch = "x86", target_arch = "x86_64"),
+        not(miri)
+    ))] {
+        mod sse2;
+        use sse2 as imp;
+    } else if #[cfg(all(target_arch = "aarch64", target_feature = "neon"))] {
+        mod neon;
+        use neon as imp;
+    } else {
+        mod generic;
+        use generic as imp;
+    }
+}
+
+mod alloc;
+pub(crate) use self::alloc::{do_alloc, Allocator, Global};
+
+mod bitmask;
+
+use self::bitmask::BitMaskIter;
+use self::imp::Group;
+
+// Branch prediction hint. This is currently only available on nightly but it
+// consistently improves performance by 10-15%.
+#[cfg(not(feature = "nightly"))]
+use core::convert::identity as likely;
+#[cfg(not(feature = "nightly"))]
+use core::convert::identity as unlikely;
+#[cfg(feature = "nightly")]
+use core::intrinsics::{likely, unlikely};
+
+// Use strict provenance functions if available.
+#[cfg(feature = "nightly")]
+use core::ptr::invalid_mut;
+// Implement it with a cast otherwise.
+#[cfg(not(feature = "nightly"))]
+#[inline(always)]
+fn invalid_mut<T>(addr: usize) -> *mut T {
+    addr as *mut T
+}
+
+#[inline]
+unsafe fn offset_from<T>(to: *const T, from: *const T) -> usize {
+    to.offset_from(from) as usize
+}
+
+/// Whether memory allocation errors should return an error or abort.
+#[derive(Copy, Clone)]
+enum Fallibility {
+    Fallible,
+    Infallible,
+}
+
+impl Fallibility {
+    /// Error to return on capacity overflow.
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn capacity_overflow(self) -> TryReserveError {
+        match self {
+            Fallibility::Fallible => TryReserveError::CapacityOverflow,
+            Fallibility::Infallible => panic!("Hash table capacity overflow"),
+        }
+    }
+
+    /// Error to return on allocation error.
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn alloc_err(self, layout: Layout) -> TryReserveError {
+        match self {
+            Fallibility::Fallible => TryReserveError::AllocError { layout },
+            Fallibility::Infallible => handle_alloc_error(layout),
+        }
+    }
+}
+
+trait SizedTypeProperties: Sized {
+    const IS_ZERO_SIZED: bool = mem::size_of::<Self>() == 0;
+    const NEEDS_DROP: bool = mem::needs_drop::<Self>();
+}
+
+impl<T> SizedTypeProperties for T {}
+
+/// Control byte value for an empty bucket.
+const EMPTY: u8 = 0b1111_1111;
+
+/// Control byte value for a deleted bucket.
+const DELETED: u8 = 0b1000_0000;
+
+/// Checks whether a control byte represents a full bucket (top bit is clear).
+#[inline]
+fn is_full(ctrl: u8) -> bool {
+    ctrl & 0x80 == 0
+}
+
+/// Checks whether a control byte represents a special value (top bit is set).
+#[inline]
+fn is_special(ctrl: u8) -> bool {
+    ctrl & 0x80 != 0
+}
+
+/// Checks whether a special control value is EMPTY (just check 1 bit).
+#[inline]
+fn special_is_empty(ctrl: u8) -> bool {
+    debug_assert!(is_special(ctrl));
+    ctrl & 0x01 != 0
+}
+
+/// Primary hash function, used to select the initial bucket to probe from.
+#[inline]
+#[allow(clippy::cast_possible_truncation)]
+fn h1(hash: u64) -> usize {
+    // On 32-bit platforms we simply ignore the higher hash bits.
+    hash as usize
+}
+
+// Constant for h2 function that grabing the top 7 bits of the hash.
+const MIN_HASH_LEN: usize = if mem::size_of::<usize>() < mem::size_of::<u64>() {
+    mem::size_of::<usize>()
+} else {
+    mem::size_of::<u64>()
+};
+
+/// Secondary hash function, saved in the low 7 bits of the control byte.
+#[inline]
+#[allow(clippy::cast_possible_truncation)]
+fn h2(hash: u64) -> u8 {
+    // Grab the top 7 bits of the hash. While the hash is normally a full 64-bit
+    // value, some hash functions (such as FxHash) produce a usize result
+    // instead, which means that the top 32 bits are 0 on 32-bit platforms.
+    // So we use MIN_HASH_LEN constant to handle this.
+    let top7 = hash >> (MIN_HASH_LEN * 8 - 7);
+    (top7 & 0x7f) as u8 // truncation
+}
+
+/// Probe sequence based on triangular numbers, which is guaranteed (since our
+/// table size is a power of two) to visit every group of elements exactly once.
+///
+/// A triangular probe has us jump by 1 more group every time. So first we
+/// jump by 1 group (meaning we just continue our linear scan), then 2 groups
+/// (skipping over 1 group), then 3 groups (skipping over 2 groups), and so on.
+///
+/// Proof that the probe will visit every group in the table:
+/// <https://fgiesen.wordpress.com/2015/02/22/triangular-numbers-mod-2n/>
+struct ProbeSeq {
+    pos: usize,
+    stride: usize,
+}
+
+impl ProbeSeq {
+    #[inline]
+    fn move_next(&mut self, bucket_mask: usize) {
+        // We should have found an empty bucket by now and ended the probe.
+        debug_assert!(
+            self.stride <= bucket_mask,
+            "Went past end of probe sequence"
+        );
+
+        self.stride += Group::WIDTH;
+        self.pos += self.stride;
+        self.pos &= bucket_mask;
+    }
+}
+
+/// Returns the number of buckets needed to hold the given number of items,
+/// taking the maximum load factor into account.
+///
+/// Returns `None` if an overflow occurs.
+// Workaround for emscripten bug emscripten-core/emscripten-fastcomp#258
+#[cfg_attr(target_os = "emscripten", inline(never))]
+#[cfg_attr(not(target_os = "emscripten"), inline)]
+fn capacity_to_buckets(cap: usize) -> Option<usize> {
+    debug_assert_ne!(cap, 0);
+
+    // For small tables we require at least 1 empty bucket so that lookups are
+    // guaranteed to terminate if an element doesn't exist in the table.
+    if cap < 8 {
+        // We don't bother with a table size of 2 buckets since that can only
+        // hold a single element. Instead we skip directly to a 4 bucket table
+        // which can hold 3 elements.
+        return Some(if cap < 4 { 4 } else { 8 });
+    }
+
+    // Otherwise require 1/8 buckets to be empty (87.5% load)
+    //
+    // Be careful when modifying this, calculate_layout relies on the
+    // overflow check here.
+    let adjusted_cap = cap.checked_mul(8)? / 7;
+
+    // Any overflows will have been caught by the checked_mul. Also, any
+    // rounding errors from the division above will be cleaned up by
+    // next_power_of_two (which can't overflow because of the previous division).
+    Some(adjusted_cap.next_power_of_two())
+}
+
+/// Returns the maximum effective capacity for the given bucket mask, taking
+/// the maximum load factor into account.
+#[inline]
+fn bucket_mask_to_capacity(bucket_mask: usize) -> usize {
+    if bucket_mask < 8 {
+        // For tables with 1/2/4/8 buckets, we always reserve one empty slot.
+        // Keep in mind that the bucket mask is one less than the bucket count.
+        bucket_mask
+    } else {
+        // For larger tables we reserve 12.5% of the slots as empty.
+        ((bucket_mask + 1) / 8) * 7
+    }
+}
+
+/// Helper which allows the max calculation for ctrl_align to be statically computed for each T
+/// while keeping the rest of `calculate_layout_for` independent of `T`
+#[derive(Copy, Clone)]
+struct TableLayout {
+    size: usize,
+    ctrl_align: usize,
+}
+
+impl TableLayout {
+    #[inline]
+    const fn new<T>() -> Self {
+        let layout = Layout::new::<T>();
+        Self {
+            size: layout.size(),
+            ctrl_align: if layout.align() > Group::WIDTH {
+                layout.align()
+            } else {
+                Group::WIDTH
+            },
+        }
+    }
+
+    #[inline]
+    fn calculate_layout_for(self, buckets: usize) -> Option<(Layout, usize)> {
+        debug_assert!(buckets.is_power_of_two());
+
+        let TableLayout { size, ctrl_align } = self;
+        // Manual layout calculation since Layout methods are not yet stable.
+        let ctrl_offset =
+            size.checked_mul(buckets)?.checked_add(ctrl_align - 1)? & !(ctrl_align - 1);
+        let len = ctrl_offset.checked_add(buckets + Group::WIDTH)?;
+
+        // We need an additional check to ensure that the allocation doesn't
+        // exceed `isize::MAX` (https://github.com/rust-lang/rust/pull/95295).
+        if len > isize::MAX as usize - (ctrl_align - 1) {
+            return None;
+        }
+
+        Some((
+            unsafe { Layout::from_size_align_unchecked(len, ctrl_align) },
+            ctrl_offset,
+        ))
+    }
+}
+
+/// A reference to an empty bucket into which an can be inserted.
+pub struct InsertSlot {
+    index: usize,
+}
+
+/// A reference to a hash table bucket containing a `T`.
+///
+/// This is usually just a pointer to the element itself. However if the element
+/// is a ZST, then we instead track the index of the element in the table so
+/// that `erase` works properly.
+pub struct Bucket<T> {
+    // Actually it is pointer to next element than element itself
+    // this is needed to maintain pointer arithmetic invariants
+    // keeping direct pointer to element introduces difficulty.
+    // Using `NonNull` for variance and niche layout
+    ptr: NonNull<T>,
+}
+
+// This Send impl is needed for rayon support. This is safe since Bucket is
+// never exposed in a public API.
+unsafe impl<T> Send for Bucket<T> {}
+
+impl<T> Clone for Bucket<T> {
+    #[inline]
+    fn clone(&self) -> Self {
+        Self { ptr: self.ptr }
+    }
+}
+
+impl<T> Bucket<T> {
+    /// Creates a [`Bucket`] that contain pointer to the data.
+    /// The pointer calculation is performed by calculating the
+    /// offset from given `base` pointer (convenience for
+    /// `base.as_ptr().sub(index)`).
+    ///
+    /// `index` is in units of `T`; e.g., an `index` of 3 represents a pointer
+    /// offset of `3 * size_of::<T>()` bytes.
+    ///
+    /// If the `T` is a ZST, then we instead track the index of the element
+    /// in the table so that `erase` works properly (return
+    /// `NonNull::new_unchecked((index + 1) as *mut T)`)
+    ///
+    /// # Safety
+    ///
+    /// If `mem::size_of::<T>() != 0`, then the safety rules are directly derived
+    /// from the safety rules for [`<*mut T>::sub`] method of `*mut T` and the safety
+    /// rules of [`NonNull::new_unchecked`] function.
+    ///
+    /// Thus, in order to uphold the safety contracts for the [`<*mut T>::sub`] method
+    /// and [`NonNull::new_unchecked`] function, as well as for the correct
+    /// logic of the work of this crate, the following rules are necessary and
+    /// sufficient:
+    ///
+    /// * the `base` pointer must not be `dangling` and must points to the
+    ///   end of the first `value element` from the `data part` of the table, i.e.
+    ///   must be the pointer that returned by [`RawTable::data_end`] or by
+    ///   [`RawTableInner::data_end<T>`];
+    ///
+    /// * `index` must not be greater than `RawTableInner.bucket_mask`, i.e.
+    ///   `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)`
+    ///   must be no greater than the number returned by the function
+    ///   [`RawTable::buckets`] or [`RawTableInner::buckets`].
+    ///
+    /// If `mem::size_of::<T>() == 0`, then the only requirement is that the
+    /// `index` must not be greater than `RawTableInner.bucket_mask`, i.e.
+    /// `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)`
+    /// must be no greater than the number returned by the function
+    /// [`RawTable::buckets`] or [`RawTableInner::buckets`].
+    ///
+    /// [`Bucket`]: crate::raw::Bucket
+    /// [`<*mut T>::sub`]: https://doc.rust-lang.org/core/primitive.pointer.html#method.sub-1
+    /// [`NonNull::new_unchecked`]: https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.new_unchecked
+    /// [`RawTable::data_end`]: crate::raw::RawTable::data_end
+    /// [`RawTableInner::data_end<T>`]: RawTableInner::data_end<T>
+    /// [`RawTable::buckets`]: crate::raw::RawTable::buckets
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    #[inline]
+    unsafe fn from_base_index(base: NonNull<T>, index: usize) -> Self {
+        // If mem::size_of::<T>() != 0 then return a pointer to an `element` in
+        // the data part of the table (we start counting from "0", so that
+        // in the expression T[last], the "last" index actually one less than the
+        // "buckets" number in the table, i.e. "last = RawTableInner.bucket_mask"):
+        //
+        //                   `from_base_index(base, 1).as_ptr()` returns a pointer that
+        //                   points here in the data part of the table
+        //                   (to the start of T1)
+        //                        |
+        //                        |        `base: NonNull<T>` must point here
+        //                        |         (to the end of T0 or to the start of C0)
+        //                        v         v
+        // [Padding], Tlast, ..., |T1|, T0, |C0, C1, ..., Clast
+        //                           ^
+        //                           `from_base_index(base, 1)` returns a pointer
+        //                           that points here in the data part of the table
+        //                           (to the end of T1)
+        //
+        // where: T0...Tlast - our stored data; C0...Clast - control bytes
+        // or metadata for data.
+        let ptr = if T::IS_ZERO_SIZED {
+            // won't overflow because index must be less than length (bucket_mask)
+            // and bucket_mask is guaranteed to be less than `isize::MAX`
+            // (see TableLayout::calculate_layout_for method)
+            invalid_mut(index + 1)
+        } else {
+            base.as_ptr().sub(index)
+        };
+        Self {
+            ptr: NonNull::new_unchecked(ptr),
+        }
+    }
+
+    /// Calculates the index of a [`Bucket`] as distance between two pointers
+    /// (convenience for `base.as_ptr().offset_from(self.ptr.as_ptr()) as usize`).
+    /// The returned value is in units of T: the distance in bytes divided by
+    /// [`core::mem::size_of::<T>()`].
+    ///
+    /// If the `T` is a ZST, then we return the index of the element in
+    /// the table so that `erase` works properly (return `self.ptr.as_ptr() as usize - 1`).
+    ///
+    /// This function is the inverse of [`from_base_index`].
+    ///
+    /// # Safety
+    ///
+    /// If `mem::size_of::<T>() != 0`, then the safety rules are directly derived
+    /// from the safety rules for [`<*const T>::offset_from`] method of `*const T`.
+    ///
+    /// Thus, in order to uphold the safety contracts for [`<*const T>::offset_from`]
+    /// method, as well as for the correct logic of the work of this crate, the
+    /// following rules are necessary and sufficient:
+    ///
+    /// * `base` contained pointer must not be `dangling` and must point to the
+    ///   end of the first `element` from the `data part` of the table, i.e.
+    ///   must be a pointer that returns by [`RawTable::data_end`] or by
+    ///   [`RawTableInner::data_end<T>`];
+    ///
+    /// * `self` also must not contain dangling pointer;
+    ///
+    /// * both `self` and `base` must be created from the same [`RawTable`]
+    ///   (or [`RawTableInner`]).
+    ///
+    /// If `mem::size_of::<T>() == 0`, this function is always safe.
+    ///
+    /// [`Bucket`]: crate::raw::Bucket
+    /// [`from_base_index`]: crate::raw::Bucket::from_base_index
+    /// [`RawTable::data_end`]: crate::raw::RawTable::data_end
+    /// [`RawTableInner::data_end<T>`]: RawTableInner::data_end<T>
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [`RawTableInner`]: RawTableInner
+    /// [`<*const T>::offset_from`]: https://doc.rust-lang.org/nightly/core/primitive.pointer.html#method.offset_from
+    #[inline]
+    unsafe fn to_base_index(&self, base: NonNull<T>) -> usize {
+        // If mem::size_of::<T>() != 0 then return an index under which we used to store the
+        // `element` in the data part of the table (we start counting from "0", so
+        // that in the expression T[last], the "last" index actually is one less than the
+        // "buckets" number in the table, i.e. "last = RawTableInner.bucket_mask").
+        // For example for 5th element in table calculation is performed like this:
+        //
+        //                        mem::size_of::<T>()
+        //                          |
+        //                          |         `self = from_base_index(base, 5)` that returns pointer
+        //                          |         that points here in tha data part of the table
+        //                          |         (to the end of T5)
+        //                          |           |                    `base: NonNull<T>` must point here
+        //                          v           |                    (to the end of T0 or to the start of C0)
+        //                        /???\         v                      v
+        // [Padding], Tlast, ..., |T10|, ..., T5|, T4, T3, T2, T1, T0, |C0, C1, C2, C3, C4, C5, ..., C10, ..., Clast
+        //                                      \__________  __________/
+        //                                                 \/
+        //                                     `bucket.to_base_index(base)` = 5
+        //                                     (base.as_ptr() as usize - self.ptr.as_ptr() as usize) / mem::size_of::<T>()
+        //
+        // where: T0...Tlast - our stored data; C0...Clast - control bytes or metadata for data.
+        if T::IS_ZERO_SIZED {
+            // this can not be UB
+            self.ptr.as_ptr() as usize - 1
+        } else {
+            offset_from(base.as_ptr(), self.ptr.as_ptr())
+        }
+    }
+
+    /// Acquires the underlying raw pointer `*mut T` to `data`.
+    ///
+    /// # Note
+    ///
+    /// If `T` is not [`Copy`], do not use `*mut T` methods that can cause calling the
+    /// destructor of `T` (for example the [`<*mut T>::drop_in_place`] method), because
+    /// for properly dropping the data we also need to clear `data` control bytes. If we
+    /// drop data, but do not clear `data control byte` it leads to double drop when
+    /// [`RawTable`] goes out of scope.
+    ///
+    /// If you modify an already initialized `value`, so [`Hash`] and [`Eq`] on the new
+    /// `T` value and its borrowed form *must* match those for the old `T` value, as the map
+    /// will not re-evaluate where the new value should go, meaning the value may become
+    /// "lost" if their location does not reflect their state.
+    ///
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [`<*mut T>::drop_in_place`]: https://doc.rust-lang.org/core/primitive.pointer.html#method.drop_in_place
+    /// [`Hash`]: https://doc.rust-lang.org/core/hash/trait.Hash.html
+    /// [`Eq`]: https://doc.rust-lang.org/core/cmp/trait.Eq.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[cfg(feature = "raw")]
+    /// # fn test() {
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::raw::{Bucket, RawTable};
+    ///
+    /// type NewHashBuilder = core::hash::BuildHasherDefault<ahash::AHasher>;
+    ///
+    /// fn make_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let hash_builder = NewHashBuilder::default();
+    /// let mut table = RawTable::new();
+    ///
+    /// let value = ("a", 100);
+    /// let hash = make_hash(&hash_builder, &value.0);
+    ///
+    /// table.insert(hash, value.clone(), |val| make_hash(&hash_builder, &val.0));
+    ///
+    /// let bucket: Bucket<(&str, i32)> = table.find(hash, |(k1, _)| k1 == &value.0).unwrap();
+    ///
+    /// assert_eq!(unsafe { &*bucket.as_ptr() }, &("a", 100));
+    /// # }
+    /// # fn main() {
+    /// #     #[cfg(feature = "raw")]
+    /// #     test()
+    /// # }
+    /// ```
+    #[inline]
+    pub fn as_ptr(&self) -> *mut T {
+        if T::IS_ZERO_SIZED {
+            // Just return an arbitrary ZST pointer which is properly aligned
+            // invalid pointer is good enough for ZST
+            invalid_mut(mem::align_of::<T>())
+        } else {
+            unsafe { self.ptr.as_ptr().sub(1) }
+        }
+    }
+
+    /// Create a new [`Bucket`] that is offset from the `self` by the given
+    /// `offset`. The pointer calculation is performed by calculating the
+    /// offset from `self` pointer (convenience for `self.ptr.as_ptr().sub(offset)`).
+    /// This function is used for iterators.
+    ///
+    /// `offset` is in units of `T`; e.g., a `offset` of 3 represents a pointer
+    /// offset of `3 * size_of::<T>()` bytes.
+    ///
+    /// # Safety
+    ///
+    /// If `mem::size_of::<T>() != 0`, then the safety rules are directly derived
+    /// from the safety rules for [`<*mut T>::sub`] method of `*mut T` and safety
+    /// rules of [`NonNull::new_unchecked`] function.
+    ///
+    /// Thus, in order to uphold the safety contracts for [`<*mut T>::sub`] method
+    /// and [`NonNull::new_unchecked`] function, as well as for the correct
+    /// logic of the work of this crate, the following rules are necessary and
+    /// sufficient:
+    ///
+    /// * `self` contained pointer must not be `dangling`;
+    ///
+    /// * `self.to_base_index() + ofset` must not be greater than `RawTableInner.bucket_mask`,
+    ///   i.e. `(self.to_base_index() + ofset) <= RawTableInner.bucket_mask` or, in other
+    ///   words, `self.to_base_index() + ofset + 1` must be no greater than the number returned
+    ///   by the function [`RawTable::buckets`] or [`RawTableInner::buckets`].
+    ///
+    /// If `mem::size_of::<T>() == 0`, then the only requirement is that the
+    /// `self.to_base_index() + ofset` must not be greater than `RawTableInner.bucket_mask`,
+    /// i.e. `(self.to_base_index() + ofset) <= RawTableInner.bucket_mask` or, in other words,
+    /// `self.to_base_index() + ofset + 1` must be no greater than the number returned by the
+    /// function [`RawTable::buckets`] or [`RawTableInner::buckets`].
+    ///
+    /// [`Bucket`]: crate::raw::Bucket
+    /// [`<*mut T>::sub`]: https://doc.rust-lang.org/core/primitive.pointer.html#method.sub-1
+    /// [`NonNull::new_unchecked`]: https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.new_unchecked
+    /// [`RawTable::buckets`]: crate::raw::RawTable::buckets
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    #[inline]
+    unsafe fn next_n(&self, offset: usize) -> Self {
+        let ptr = if T::IS_ZERO_SIZED {
+            // invalid pointer is good enough for ZST
+            invalid_mut(self.ptr.as_ptr() as usize + offset)
+        } else {
+            self.ptr.as_ptr().sub(offset)
+        };
+        Self {
+            ptr: NonNull::new_unchecked(ptr),
+        }
+    }
+
+    /// Executes the destructor (if any) of the pointed-to `data`.
+    ///
+    /// # Safety
+    ///
+    /// See [`ptr::drop_in_place`] for safety concerns.
+    ///
+    /// You should use [`RawTable::erase`] instead of this function,
+    /// or be careful with calling this function directly, because for
+    /// properly dropping the data we need also clear `data` control bytes.
+    /// If we drop data, but do not erase `data control byte` it leads to
+    /// double drop when [`RawTable`] goes out of scope.
+    ///
+    /// [`ptr::drop_in_place`]: https://doc.rust-lang.org/core/ptr/fn.drop_in_place.html
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [`RawTable::erase`]: crate::raw::RawTable::erase
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(crate) unsafe fn drop(&self) {
+        self.as_ptr().drop_in_place();
+    }
+
+    /// Reads the `value` from `self` without moving it. This leaves the
+    /// memory in `self` unchanged.
+    ///
+    /// # Safety
+    ///
+    /// See [`ptr::read`] for safety concerns.
+    ///
+    /// You should use [`RawTable::remove`] instead of this function,
+    /// or be careful with calling this function directly, because compiler
+    /// calls its destructor when readed `value` goes out of scope. It
+    /// can cause double dropping when [`RawTable`] goes out of scope,
+    /// because of not erased `data control byte`.
+    ///
+    /// [`ptr::read`]: https://doc.rust-lang.org/core/ptr/fn.read.html
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [`RawTable::remove`]: crate::raw::RawTable::remove
+    #[inline]
+    pub(crate) unsafe fn read(&self) -> T {
+        self.as_ptr().read()
+    }
+
+    /// Overwrites a memory location with the given `value` without reading
+    /// or dropping the old value (like [`ptr::write`] function).
+    ///
+    /// # Safety
+    ///
+    /// See [`ptr::write`] for safety concerns.
+    ///
+    /// # Note
+    ///
+    /// [`Hash`] and [`Eq`] on the new `T` value and its borrowed form *must* match
+    /// those for the old `T` value, as the map will not re-evaluate where the new
+    /// value should go, meaning the value may become "lost" if their location
+    /// does not reflect their state.
+    ///
+    /// [`ptr::write`]: https://doc.rust-lang.org/core/ptr/fn.write.html
+    /// [`Hash`]: https://doc.rust-lang.org/core/hash/trait.Hash.html
+    /// [`Eq`]: https://doc.rust-lang.org/core/cmp/trait.Eq.html
+    #[inline]
+    pub(crate) unsafe fn write(&self, val: T) {
+        self.as_ptr().write(val);
+    }
+
+    /// Returns a shared immutable reference to the `value`.
+    ///
+    /// # Safety
+    ///
+    /// See [`NonNull::as_ref`] for safety concerns.
+    ///
+    /// [`NonNull::as_ref`]: https://doc.rust-lang.org/core/ptr/struct.NonNull.html#method.as_ref
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[cfg(feature = "raw")]
+    /// # fn test() {
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::raw::{Bucket, RawTable};
+    ///
+    /// type NewHashBuilder = core::hash::BuildHasherDefault<ahash::AHasher>;
+    ///
+    /// fn make_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let hash_builder = NewHashBuilder::default();
+    /// let mut table = RawTable::new();
+    ///
+    /// let value: (&str, String) = ("A pony", "is a small horse".to_owned());
+    /// let hash = make_hash(&hash_builder, &value.0);
+    ///
+    /// table.insert(hash, value.clone(), |val| make_hash(&hash_builder, &val.0));
+    ///
+    /// let bucket: Bucket<(&str, String)> = table.find(hash, |(k, _)| k == &value.0).unwrap();
+    ///
+    /// assert_eq!(
+    ///     unsafe { bucket.as_ref() },
+    ///     &("A pony", "is a small horse".to_owned())
+    /// );
+    /// # }
+    /// # fn main() {
+    /// #     #[cfg(feature = "raw")]
+    /// #     test()
+    /// # }
+    /// ```
+    #[inline]
+    pub unsafe fn as_ref<'a>(&self) -> &'a T {
+        &*self.as_ptr()
+    }
+
+    /// Returns a unique mutable reference to the `value`.
+    ///
+    /// # Safety
+    ///
+    /// See [`NonNull::as_mut`] for safety concerns.
+    ///
+    /// # Note
+    ///
+    /// [`Hash`] and [`Eq`] on the new `T` value and its borrowed form *must* match
+    /// those for the old `T` value, as the map will not re-evaluate where the new
+    /// value should go, meaning the value may become "lost" if their location
+    /// does not reflect their state.
+    ///
+    /// [`NonNull::as_mut`]: https://doc.rust-lang.org/core/ptr/struct.NonNull.html#method.as_mut
+    /// [`Hash`]: https://doc.rust-lang.org/core/hash/trait.Hash.html
+    /// [`Eq`]: https://doc.rust-lang.org/core/cmp/trait.Eq.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[cfg(feature = "raw")]
+    /// # fn test() {
+    /// use core::hash::{BuildHasher, Hash};
+    /// use hashbrown::raw::{Bucket, RawTable};
+    ///
+    /// type NewHashBuilder = core::hash::BuildHasherDefault<ahash::AHasher>;
+    ///
+    /// fn make_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
+    ///     use core::hash::Hasher;
+    ///     let mut state = hash_builder.build_hasher();
+    ///     key.hash(&mut state);
+    ///     state.finish()
+    /// }
+    ///
+    /// let hash_builder = NewHashBuilder::default();
+    /// let mut table = RawTable::new();
+    ///
+    /// let value: (&str, String) = ("A pony", "is a small horse".to_owned());
+    /// let hash = make_hash(&hash_builder, &value.0);
+    ///
+    /// table.insert(hash, value.clone(), |val| make_hash(&hash_builder, &val.0));
+    ///
+    /// let bucket: Bucket<(&str, String)> = table.find(hash, |(k, _)| k == &value.0).unwrap();
+    ///
+    /// unsafe {
+    ///     bucket
+    ///         .as_mut()
+    ///         .1
+    ///         .push_str(" less than 147 cm at the withers")
+    /// };
+    /// assert_eq!(
+    ///     unsafe { bucket.as_ref() },
+    ///     &(
+    ///         "A pony",
+    ///         "is a small horse less than 147 cm at the withers".to_owned()
+    ///     )
+    /// );
+    /// # }
+    /// # fn main() {
+    /// #     #[cfg(feature = "raw")]
+    /// #     test()
+    /// # }
+    /// ```
+    #[inline]
+    pub unsafe fn as_mut<'a>(&self) -> &'a mut T {
+        &mut *self.as_ptr()
+    }
+
+    /// Copies `size_of<T>` bytes from `other` to `self`. The source
+    /// and destination may *not* overlap.
+    ///
+    /// # Safety
+    ///
+    /// See [`ptr::copy_nonoverlapping`] for safety concerns.
+    ///
+    /// Like [`read`], `copy_nonoverlapping` creates a bitwise copy of `T`, regardless of
+    /// whether `T` is [`Copy`]. If `T` is not [`Copy`], using *both* the values
+    /// in the region beginning at `*self` and the region beginning at `*other` can
+    /// [violate memory safety].
+    ///
+    /// # Note
+    ///
+    /// [`Hash`] and [`Eq`] on the new `T` value and its borrowed form *must* match
+    /// those for the old `T` value, as the map will not re-evaluate where the new
+    /// value should go, meaning the value may become "lost" if their location
+    /// does not reflect their state.
+    ///
+    /// [`ptr::copy_nonoverlapping`]: https://doc.rust-lang.org/core/ptr/fn.copy_nonoverlapping.html
+    /// [`read`]: https://doc.rust-lang.org/core/ptr/fn.read.html
+    /// [violate memory safety]: https://doc.rust-lang.org/std/ptr/fn.read.html#ownership-of-the-returned-value
+    /// [`Hash`]: https://doc.rust-lang.org/core/hash/trait.Hash.html
+    /// [`Eq`]: https://doc.rust-lang.org/core/cmp/trait.Eq.html
+    #[cfg(feature = "raw")]
+    #[inline]
+    pub unsafe fn copy_from_nonoverlapping(&self, other: &Self) {
+        self.as_ptr().copy_from_nonoverlapping(other.as_ptr(), 1);
+    }
+}
+
+/// A raw hash table with an unsafe API.
+pub struct RawTable<T, A: Allocator = Global> {
+    table: RawTableInner,
+    alloc: A,
+    // Tell dropck that we own instances of T.
+    marker: PhantomData<T>,
+}
+
+/// Non-generic part of `RawTable` which allows functions to be instantiated only once regardless
+/// of how many different key-value types are used.
+struct RawTableInner {
+    // Mask to get an index from a hash value. The value is one less than the
+    // number of buckets in the table.
+    bucket_mask: usize,
+
+    // [Padding], T1, T2, ..., Tlast, C1, C2, ...
+    //                                ^ points here
+    ctrl: NonNull<u8>,
+
+    // Number of elements that can be inserted before we need to grow the table
+    growth_left: usize,
+
+    // Number of elements in the table, only really used by len()
+    items: usize,
+}
+
+impl<T> RawTable<T, Global> {
+    /// Creates a new empty hash table without allocating any memory.
+    ///
+    /// In effect this returns a table with exactly 1 bucket. However we can
+    /// leave the data pointer dangling since that bucket is never written to
+    /// due to our load factor forcing us to always have at least 1 free bucket.
+    #[inline]
+    pub const fn new() -> Self {
+        Self {
+            table: RawTableInner::NEW,
+            alloc: Global,
+            marker: PhantomData,
+        }
+    }
+
+    /// Attempts to allocate a new hash table with at least enough capacity
+    /// for inserting the given number of elements without reallocating.
+    #[cfg(feature = "raw")]
+    pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+        Self::try_with_capacity_in(capacity, Global)
+    }
+
+    /// Allocates a new hash table with at least enough capacity for inserting
+    /// the given number of elements without reallocating.
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self::with_capacity_in(capacity, Global)
+    }
+}
+
+impl<T, A: Allocator> RawTable<T, A> {
+    const TABLE_LAYOUT: TableLayout = TableLayout::new::<T>();
+
+    /// Creates a new empty hash table without allocating any memory, using the
+    /// given allocator.
+    ///
+    /// In effect this returns a table with exactly 1 bucket. However we can
+    /// leave the data pointer dangling since that bucket is never written to
+    /// due to our load factor forcing us to always have at least 1 free bucket.
+    #[inline]
+    pub const fn new_in(alloc: A) -> Self {
+        Self {
+            table: RawTableInner::NEW,
+            alloc,
+            marker: PhantomData,
+        }
+    }
+
+    /// Allocates a new hash table with the given number of buckets.
+    ///
+    /// The control bytes are left uninitialized.
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn new_uninitialized(
+        alloc: A,
+        buckets: usize,
+        fallibility: Fallibility,
+    ) -> Result<Self, TryReserveError> {
+        debug_assert!(buckets.is_power_of_two());
+
+        Ok(Self {
+            table: RawTableInner::new_uninitialized(
+                &alloc,
+                Self::TABLE_LAYOUT,
+                buckets,
+                fallibility,
+            )?,
+            alloc,
+            marker: PhantomData,
+        })
+    }
+
+    /// Attempts to allocate a new hash table using the given allocator, with at least enough
+    /// capacity for inserting the given number of elements without reallocating.
+    #[cfg(feature = "raw")]
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Ok(Self {
+            table: RawTableInner::fallible_with_capacity(
+                &alloc,
+                Self::TABLE_LAYOUT,
+                capacity,
+                Fallibility::Fallible,
+            )?,
+            alloc,
+            marker: PhantomData,
+        })
+    }
+
+    /// Allocates a new hash table using the given allocator, with at least enough capacity for
+    /// inserting the given number of elements without reallocating.
+    pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
+        Self {
+            table: RawTableInner::with_capacity(&alloc, Self::TABLE_LAYOUT, capacity),
+            alloc,
+            marker: PhantomData,
+        }
+    }
+
+    /// Returns a reference to the underlying allocator.
+    #[inline]
+    pub fn allocator(&self) -> &A {
+        &self.alloc
+    }
+
+    /// Returns pointer to one past last element of data table.
+    #[inline]
+    pub unsafe fn data_end(&self) -> NonNull<T> {
+        NonNull::new_unchecked(self.table.ctrl.as_ptr().cast())
+    }
+
+    /// Returns pointer to start of data table.
+    #[inline]
+    #[cfg(any(feature = "raw", feature = "nightly"))]
+    pub unsafe fn data_start(&self) -> NonNull<T> {
+        NonNull::new_unchecked(self.data_end().as_ptr().wrapping_sub(self.buckets()))
+    }
+
+    /// Return the information about memory allocated by the table.
+    ///
+    /// `RawTable` allocates single memory block to store both data and metadata.
+    /// This function returns allocation size and alignment and the beginning of the area.
+    /// These are the arguments which will be passed to `dealloc` when the table is dropped.
+    ///
+    /// This function might be useful for memory profiling.
+    #[inline]
+    #[cfg(feature = "raw")]
+    pub fn allocation_info(&self) -> (NonNull<u8>, Layout) {
+        // SAFETY: We use the same `table_layout` that was used to allocate
+        // this table.
+        unsafe { self.table.allocation_info_or_zero(Self::TABLE_LAYOUT) }
+    }
+
+    /// Returns the index of a bucket from a `Bucket`.
+    #[inline]
+    pub unsafe fn bucket_index(&self, bucket: &Bucket<T>) -> usize {
+        bucket.to_base_index(self.data_end())
+    }
+
+    /// Returns a pointer to an element in the table.
+    #[inline]
+    pub unsafe fn bucket(&self, index: usize) -> Bucket<T> {
+        debug_assert_ne!(self.table.bucket_mask, 0);
+        debug_assert!(index < self.buckets());
+        Bucket::from_base_index(self.data_end(), index)
+    }
+
+    /// Erases an element from the table without dropping it.
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn erase_no_drop(&mut self, item: &Bucket<T>) {
+        let index = self.bucket_index(item);
+        self.table.erase(index);
+    }
+
+    /// Erases an element from the table, dropping it in place.
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::needless_pass_by_value)]
+    pub unsafe fn erase(&mut self, item: Bucket<T>) {
+        // Erase the element from the table first since drop might panic.
+        self.erase_no_drop(&item);
+        item.drop();
+    }
+
+    /// Finds and erases an element from the table, dropping it in place.
+    /// Returns true if an element was found.
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn erase_entry(&mut self, hash: u64, eq: impl FnMut(&T) -> bool) -> bool {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        if let Some(bucket) = self.find(hash, eq) {
+            unsafe {
+                self.erase(bucket);
+            }
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Removes an element from the table, returning it.
+    ///
+    /// This also returns an `InsertSlot` pointing to the newly free bucket.
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[allow(clippy::needless_pass_by_value)]
+    pub unsafe fn remove(&mut self, item: Bucket<T>) -> (T, InsertSlot) {
+        self.erase_no_drop(&item);
+        (
+            item.read(),
+            InsertSlot {
+                index: self.bucket_index(&item),
+            },
+        )
+    }
+
+    /// Finds and removes an element from the table, returning it.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(&mut self, hash: u64, eq: impl FnMut(&T) -> bool) -> Option<T> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.find(hash, eq) {
+            Some(bucket) => Some(unsafe { self.remove(bucket).0 }),
+            None => None,
+        }
+    }
+
+    /// Marks all table buckets as empty without dropping their contents.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn clear_no_drop(&mut self) {
+        self.table.clear_no_drop();
+    }
+
+    /// Removes all elements from the table without freeing the backing memory.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn clear(&mut self) {
+        if self.is_empty() {
+            // Special case empty table to avoid surprising O(capacity) time.
+            return;
+        }
+        // Ensure that the table is reset even if one of the drops panic
+        let mut self_ = guard(self, |self_| self_.clear_no_drop());
+        unsafe {
+            // SAFETY: ScopeGuard sets to zero the `items` field of the table
+            // even in case of panic during the dropping of the elements so
+            // that there will be no double drop of the elements.
+            self_.table.drop_elements::<T>();
+        }
+    }
+
+    /// Shrinks the table to fit `max(self.len(), min_size)` elements.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn shrink_to(&mut self, min_size: usize, hasher: impl Fn(&T) -> u64) {
+        // Calculate the minimal number of elements that we need to reserve
+        // space for.
+        let min_size = usize::max(self.table.items, min_size);
+        if min_size == 0 {
+            let mut old_inner = mem::replace(&mut self.table, RawTableInner::NEW);
+            unsafe {
+                // SAFETY:
+                // 1. We call the function only once;
+                // 2. We know for sure that `alloc` and `table_layout` matches the [`Allocator`]
+                //    and [`TableLayout`] that were used to allocate this table.
+                // 3. If any elements' drop function panics, then there will only be a memory leak,
+                //    because we have replaced the inner table with a new one.
+                old_inner.drop_inner_table::<T, _>(&self.alloc, Self::TABLE_LAYOUT);
+            }
+            return;
+        }
+
+        // Calculate the number of buckets that we need for this number of
+        // elements. If the calculation overflows then the requested bucket
+        // count must be larger than what we have right and nothing needs to be
+        // done.
+        let min_buckets = match capacity_to_buckets(min_size) {
+            Some(buckets) => buckets,
+            None => return,
+        };
+
+        // If we have more buckets than we need, shrink the table.
+        if min_buckets < self.buckets() {
+            // Fast path if the table is empty
+            if self.table.items == 0 {
+                let new_inner =
+                    RawTableInner::with_capacity(&self.alloc, Self::TABLE_LAYOUT, min_size);
+                let mut old_inner = mem::replace(&mut self.table, new_inner);
+                unsafe {
+                    // SAFETY:
+                    // 1. We call the function only once;
+                    // 2. We know for sure that `alloc` and `table_layout` matches the [`Allocator`]
+                    //    and [`TableLayout`] that were used to allocate this table.
+                    // 3. If any elements' drop function panics, then there will only be a memory leak,
+                    //    because we have replaced the inner table with a new one.
+                    old_inner.drop_inner_table::<T, _>(&self.alloc, Self::TABLE_LAYOUT);
+                }
+            } else {
+                // Avoid `Result::unwrap_or_else` because it bloats LLVM IR.
+                unsafe {
+                    // SAFETY:
+                    // 1. We know for sure that `min_size >= self.table.items`.
+                    // 2. The [`RawTableInner`] must already have properly initialized control bytes since
+                    //    we will never expose RawTable::new_uninitialized in a public API.
+                    if self
+                        .resize(min_size, hasher, Fallibility::Infallible)
+                        .is_err()
+                    {
+                        // SAFETY: The result of calling the `resize` function cannot be an error
+                        // because `fallibility == Fallibility::Infallible.
+                        hint::unreachable_unchecked()
+                    }
+                }
+            }
+        }
+    }
+
+    /// Ensures that at least `additional` items can be inserted into the table
+    /// without reallocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn reserve(&mut self, additional: usize, hasher: impl Fn(&T) -> u64) {
+        if unlikely(additional > self.table.growth_left) {
+            // Avoid `Result::unwrap_or_else` because it bloats LLVM IR.
+            unsafe {
+                // SAFETY: The [`RawTableInner`] must already have properly initialized control
+                // bytes since we will never expose RawTable::new_uninitialized in a public API.
+                if self
+                    .reserve_rehash(additional, hasher, Fallibility::Infallible)
+                    .is_err()
+                {
+                    // SAFETY: All allocation errors will be caught inside `RawTableInner::reserve_rehash`.
+                    hint::unreachable_unchecked()
+                }
+            }
+        }
+    }
+
+    /// Tries to ensure that at least `additional` items can be inserted into
+    /// the table without reallocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn try_reserve(
+        &mut self,
+        additional: usize,
+        hasher: impl Fn(&T) -> u64,
+    ) -> Result<(), TryReserveError> {
+        if additional > self.table.growth_left {
+            // SAFETY: The [`RawTableInner`] must already have properly initialized control
+            // bytes since we will never expose RawTable::new_uninitialized in a public API.
+            unsafe { self.reserve_rehash(additional, hasher, Fallibility::Fallible) }
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Out-of-line slow path for `reserve` and `try_reserve`.
+    ///
+    /// # Safety
+    ///
+    /// The [`RawTableInner`] must have properly initialized control bytes,
+    /// otherwise calling this function results in [`undefined behavior`]
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[cold]
+    #[inline(never)]
+    unsafe fn reserve_rehash(
+        &mut self,
+        additional: usize,
+        hasher: impl Fn(&T) -> u64,
+        fallibility: Fallibility,
+    ) -> Result<(), TryReserveError> {
+        unsafe {
+            // SAFETY:
+            // 1. We know for sure that `alloc` and `layout` matches the [`Allocator`] and
+            //    [`TableLayout`] that were used to allocate this table.
+            // 2. The `drop` function is the actual drop function of the elements stored in
+            //    the table.
+            // 3. The caller ensures that the control bytes of the `RawTableInner`
+            //    are already initialized.
+            self.table.reserve_rehash_inner(
+                &self.alloc,
+                additional,
+                &|table, index| hasher(table.bucket::<T>(index).as_ref()),
+                fallibility,
+                Self::TABLE_LAYOUT,
+                if T::NEEDS_DROP {
+                    Some(mem::transmute(ptr::drop_in_place::<T> as unsafe fn(*mut T)))
+                } else {
+                    None
+                },
+            )
+        }
+    }
+
+    /// Allocates a new table of a different size and moves the contents of the
+    /// current table into it.
+    ///
+    /// # Safety
+    ///
+    /// The [`RawTableInner`] must have properly initialized control bytes,
+    /// otherwise calling this function results in [`undefined behavior`]
+    ///
+    /// The caller of this function must ensure that `capacity >= self.table.items`
+    /// otherwise:
+    ///
+    /// * If `self.table.items != 0`, calling of this function with `capacity`
+    ///   equal to 0 (`capacity == 0`) results in [`undefined behavior`].
+    ///
+    /// * If `capacity_to_buckets(capacity) < Group::WIDTH` and
+    ///   `self.table.items > capacity_to_buckets(capacity)`
+    ///   calling this function results in [`undefined behavior`].
+    ///
+    /// * If `capacity_to_buckets(capacity) >= Group::WIDTH` and
+    ///   `self.table.items > capacity_to_buckets(capacity)`
+    ///   calling this function are never return (will go into an
+    ///   infinite loop).
+    ///
+    /// See [`RawTableInner::find_insert_slot`] for more information.
+    ///
+    /// [`RawTableInner::find_insert_slot`]: RawTableInner::find_insert_slot
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    unsafe fn resize(
+        &mut self,
+        capacity: usize,
+        hasher: impl Fn(&T) -> u64,
+        fallibility: Fallibility,
+    ) -> Result<(), TryReserveError> {
+        // SAFETY:
+        // 1. The caller of this function guarantees that `capacity >= self.table.items`.
+        // 2. We know for sure that `alloc` and `layout` matches the [`Allocator`] and
+        //    [`TableLayout`] that were used to allocate this table.
+        // 3. The caller ensures that the control bytes of the `RawTableInner`
+        //    are already initialized.
+        self.table.resize_inner(
+            &self.alloc,
+            capacity,
+            &|table, index| hasher(table.bucket::<T>(index).as_ref()),
+            fallibility,
+            Self::TABLE_LAYOUT,
+        )
+    }
+
+    /// Inserts a new element into the table, and returns its raw bucket.
+    ///
+    /// This does not check if the given element already exists in the table.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64) -> Bucket<T> {
+        unsafe {
+            // SAFETY:
+            // 1. The [`RawTableInner`] must already have properly initialized control bytes since
+            //    we will never expose `RawTable::new_uninitialized` in a public API.
+            //
+            // 2. We reserve additional space (if necessary) right after calling this function.
+            let mut slot = self.table.find_insert_slot(hash);
+
+            // We can avoid growing the table once we have reached our load factor if we are replacing
+            // a tombstone. This works since the number of EMPTY slots does not change in this case.
+            //
+            // SAFETY: The function is guaranteed to return [`InsertSlot`] that contains an index
+            // in the range `0..=self.buckets()`.
+            let old_ctrl = *self.table.ctrl(slot.index);
+            if unlikely(self.table.growth_left == 0 && special_is_empty(old_ctrl)) {
+                self.reserve(1, hasher);
+                // SAFETY: We know for sure that `RawTableInner` has control bytes
+                // initialized and that there is extra space in the table.
+                slot = self.table.find_insert_slot(hash);
+            }
+
+            self.insert_in_slot(hash, slot, value)
+        }
+    }
+
+    /// Attempts to insert a new element without growing the table and return its raw bucket.
+    ///
+    /// Returns an `Err` containing the given element if inserting it would require growing the
+    /// table.
+    ///
+    /// This does not check if the given element already exists in the table.
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn try_insert_no_grow(&mut self, hash: u64, value: T) -> Result<Bucket<T>, T> {
+        unsafe {
+            match self.table.prepare_insert_no_grow(hash) {
+                Ok(index) => {
+                    let bucket = self.bucket(index);
+                    bucket.write(value);
+                    Ok(bucket)
+                }
+                Err(()) => Err(value),
+            }
+        }
+    }
+
+    /// Inserts a new element into the table, and returns a mutable reference to it.
+    ///
+    /// This does not check if the given element already exists in the table.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_entry(&mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64) -> &mut T {
+        unsafe { self.insert(hash, value, hasher).as_mut() }
+    }
+
+    /// Inserts a new element into the table, without growing the table.
+    ///
+    /// There must be enough space in the table to insert the new element.
+    ///
+    /// This does not check if the given element already exists in the table.
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[cfg(any(feature = "raw", feature = "rustc-internal-api"))]
+    pub unsafe fn insert_no_grow(&mut self, hash: u64, value: T) -> Bucket<T> {
+        let (index, old_ctrl) = self.table.prepare_insert_slot(hash);
+        let bucket = self.table.bucket(index);
+
+        // If we are replacing a DELETED entry then we don't need to update
+        // the load counter.
+        self.table.growth_left -= special_is_empty(old_ctrl) as usize;
+
+        bucket.write(value);
+        self.table.items += 1;
+        bucket
+    }
+
+    /// Temporary removes a bucket, applying the given function to the removed
+    /// element and optionally put back the returned value in the same bucket.
+    ///
+    /// Returns `true` if the bucket still contains an element
+    ///
+    /// This does not check if the given bucket is actually occupied.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub unsafe fn replace_bucket_with<F>(&mut self, bucket: Bucket<T>, f: F) -> bool
+    where
+        F: FnOnce(T) -> Option<T>,
+    {
+        let index = self.bucket_index(&bucket);
+        let old_ctrl = *self.table.ctrl(index);
+        debug_assert!(self.is_bucket_full(index));
+        let old_growth_left = self.table.growth_left;
+        let item = self.remove(bucket).0;
+        if let Some(new_item) = f(item) {
+            self.table.growth_left = old_growth_left;
+            self.table.set_ctrl(index, old_ctrl);
+            self.table.items += 1;
+            self.bucket(index).write(new_item);
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Searches for an element in the table. If the element is not found,
+    /// returns `Err` with the position of a slot where an element with the
+    /// same hash could be inserted.
+    ///
+    /// This function may resize the table if additional space is required for
+    /// inserting an element.
+    #[inline]
+    pub fn find_or_find_insert_slot(
+        &mut self,
+        hash: u64,
+        mut eq: impl FnMut(&T) -> bool,
+        hasher: impl Fn(&T) -> u64,
+    ) -> Result<Bucket<T>, InsertSlot> {
+        self.reserve(1, hasher);
+
+        unsafe {
+            // SAFETY:
+            // 1. We know for sure that there is at least one empty `bucket` in the table.
+            // 2. The [`RawTableInner`] must already have properly initialized control bytes since we will
+            //    never expose `RawTable::new_uninitialized` in a public API.
+            // 3. The `find_or_find_insert_slot_inner` function returns the `index` of only the full bucket,
+            //    which is in the range `0..self.buckets()` (since there is at least one empty `bucket` in
+            //    the table), so calling `self.bucket(index)` and `Bucket::as_ref` is safe.
+            match self
+                .table
+                .find_or_find_insert_slot_inner(hash, &mut |index| eq(self.bucket(index).as_ref()))
+            {
+                // SAFETY: See explanation above.
+                Ok(index) => Ok(self.bucket(index)),
+                Err(slot) => Err(slot),
+            }
+        }
+    }
+
+    /// Inserts a new element into the table in the given slot, and returns its
+    /// raw bucket.
+    ///
+    /// # Safety
+    ///
+    /// `slot` must point to a slot previously returned by
+    /// `find_or_find_insert_slot`, and no mutation of the table must have
+    /// occurred since that call.
+    #[inline]
+    pub unsafe fn insert_in_slot(&mut self, hash: u64, slot: InsertSlot, value: T) -> Bucket<T> {
+        let old_ctrl = *self.table.ctrl(slot.index);
+        self.table.record_item_insert_at(slot.index, old_ctrl, hash);
+
+        let bucket = self.bucket(slot.index);
+        bucket.write(value);
+        bucket
+    }
+
+    /// Searches for an element in the table.
+    #[inline]
+    pub fn find(&self, hash: u64, mut eq: impl FnMut(&T) -> bool) -> Option<Bucket<T>> {
+        unsafe {
+            // SAFETY:
+            // 1. The [`RawTableInner`] must already have properly initialized control bytes since we
+            //    will never expose `RawTable::new_uninitialized` in a public API.
+            // 1. The `find_inner` function returns the `index` of only the full bucket, which is in
+            //    the range `0..self.buckets()`, so calling `self.bucket(index)` and `Bucket::as_ref`
+            //    is safe.
+            let result = self
+                .table
+                .find_inner(hash, &mut |index| eq(self.bucket(index).as_ref()));
+
+            // Avoid `Option::map` because it bloats LLVM IR.
+            match result {
+                // SAFETY: See explanation above.
+                Some(index) => Some(self.bucket(index)),
+                None => None,
+            }
+        }
+    }
+
+    /// Gets a reference to an element in the table.
+    #[inline]
+    pub fn get(&self, hash: u64, eq: impl FnMut(&T) -> bool) -> Option<&T> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.find(hash, eq) {
+            Some(bucket) => Some(unsafe { bucket.as_ref() }),
+            None => None,
+        }
+    }
+
+    /// Gets a mutable reference to an element in the table.
+    #[inline]
+    pub fn get_mut(&mut self, hash: u64, eq: impl FnMut(&T) -> bool) -> Option<&mut T> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.find(hash, eq) {
+            Some(bucket) => Some(unsafe { bucket.as_mut() }),
+            None => None,
+        }
+    }
+
+    /// Attempts to get mutable references to `N` entries in the table at once.
+    ///
+    /// Returns an array of length `N` with the results of each query.
+    ///
+    /// At most one mutable reference will be returned to any entry. `None` will be returned if any
+    /// of the hashes are duplicates. `None` will be returned if the hash is not found.
+    ///
+    /// The `eq` argument should be a closure such that `eq(i, k)` returns true if `k` is equal to
+    /// the `i`th key to be looked up.
+    pub fn get_many_mut<const N: usize>(
+        &mut self,
+        hashes: [u64; N],
+        eq: impl FnMut(usize, &T) -> bool,
+    ) -> Option<[&'_ mut T; N]> {
+        unsafe {
+            let ptrs = self.get_many_mut_pointers(hashes, eq)?;
+
+            for (i, &cur) in ptrs.iter().enumerate() {
+                if ptrs[..i].iter().any(|&prev| ptr::eq::<T>(prev, cur)) {
+                    return None;
+                }
+            }
+            // All bucket are distinct from all previous buckets so we're clear to return the result
+            // of the lookup.
+
+            // TODO use `MaybeUninit::array_assume_init` here instead once that's stable.
+            Some(mem::transmute_copy(&ptrs))
+        }
+    }
+
+    pub unsafe fn get_many_unchecked_mut<const N: usize>(
+        &mut self,
+        hashes: [u64; N],
+        eq: impl FnMut(usize, &T) -> bool,
+    ) -> Option<[&'_ mut T; N]> {
+        let ptrs = self.get_many_mut_pointers(hashes, eq)?;
+        Some(mem::transmute_copy(&ptrs))
+    }
+
+    unsafe fn get_many_mut_pointers<const N: usize>(
+        &mut self,
+        hashes: [u64; N],
+        mut eq: impl FnMut(usize, &T) -> bool,
+    ) -> Option<[*mut T; N]> {
+        // TODO use `MaybeUninit::uninit_array` here instead once that's stable.
+        let mut outs: MaybeUninit<[*mut T; N]> = MaybeUninit::uninit();
+        let outs_ptr = outs.as_mut_ptr();
+
+        for (i, &hash) in hashes.iter().enumerate() {
+            let cur = self.find(hash, |k| eq(i, k))?;
+            *(*outs_ptr).get_unchecked_mut(i) = cur.as_mut();
+        }
+
+        // TODO use `MaybeUninit::array_assume_init` here instead once that's stable.
+        Some(outs.assume_init())
+    }
+
+    /// Returns the number of elements the map can hold without reallocating.
+    ///
+    /// This number is a lower bound; the table might be able to hold
+    /// more, but is guaranteed to be able to hold at least this many.
+    #[inline]
+    pub fn capacity(&self) -> usize {
+        self.table.items + self.table.growth_left
+    }
+
+    /// Returns the number of elements in the table.
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.table.items
+    }
+
+    /// Returns `true` if the table contains no elements.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Returns the number of buckets in the table.
+    #[inline]
+    pub fn buckets(&self) -> usize {
+        self.table.bucket_mask + 1
+    }
+
+    /// Checks whether the bucket at `index` is full.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure `index` is less than the number of buckets.
+    #[inline]
+    pub unsafe fn is_bucket_full(&self, index: usize) -> bool {
+        self.table.is_bucket_full(index)
+    }
+
+    /// Returns an iterator over every element in the table. It is up to
+    /// the caller to ensure that the `RawTable` outlives the `RawIter`.
+    /// Because we cannot make the `next` method unsafe on the `RawIter`
+    /// struct, we have to make the `iter` method unsafe.
+    #[inline]
+    pub unsafe fn iter(&self) -> RawIter<T> {
+        // SAFETY:
+        // 1. The caller must uphold the safety contract for `iter` method.
+        // 2. The [`RawTableInner`] must already have properly initialized control bytes since
+        //    we will never expose RawTable::new_uninitialized in a public API.
+        self.table.iter()
+    }
+
+    /// Returns an iterator over occupied buckets that could match a given hash.
+    ///
+    /// `RawTable` only stores 7 bits of the hash value, so this iterator may
+    /// return items that have a hash value different than the one provided. You
+    /// should always validate the returned values before using them.
+    ///
+    /// It is up to the caller to ensure that the `RawTable` outlives the
+    /// `RawIterHash`. Because we cannot make the `next` method unsafe on the
+    /// `RawIterHash` struct, we have to make the `iter_hash` method unsafe.
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[cfg(feature = "raw")]
+    pub unsafe fn iter_hash(&self, hash: u64) -> RawIterHash<T> {
+        RawIterHash::new(self, hash)
+    }
+
+    /// Returns an iterator which removes all elements from the table without
+    /// freeing the memory.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn drain(&mut self) -> RawDrain<'_, T, A> {
+        unsafe {
+            let iter = self.iter();
+            self.drain_iter_from(iter)
+        }
+    }
+
+    /// Returns an iterator which removes all elements from the table without
+    /// freeing the memory.
+    ///
+    /// Iteration starts at the provided iterator's current location.
+    ///
+    /// It is up to the caller to ensure that the iterator is valid for this
+    /// `RawTable` and covers all items that remain in the table.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub unsafe fn drain_iter_from(&mut self, iter: RawIter<T>) -> RawDrain<'_, T, A> {
+        debug_assert_eq!(iter.len(), self.len());
+        RawDrain {
+            iter,
+            table: mem::replace(&mut self.table, RawTableInner::NEW),
+            orig_table: NonNull::from(&mut self.table),
+            marker: PhantomData,
+        }
+    }
+
+    /// Returns an iterator which consumes all elements from the table.
+    ///
+    /// Iteration starts at the provided iterator's current location.
+    ///
+    /// It is up to the caller to ensure that the iterator is valid for this
+    /// `RawTable` and covers all items that remain in the table.
+    pub unsafe fn into_iter_from(self, iter: RawIter<T>) -> RawIntoIter<T, A> {
+        debug_assert_eq!(iter.len(), self.len());
+
+        let allocation = self.into_allocation();
+        RawIntoIter {
+            iter,
+            allocation,
+            marker: PhantomData,
+        }
+    }
+
+    /// Converts the table into a raw allocation. The contents of the table
+    /// should be dropped using a `RawIter` before freeing the allocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(crate) fn into_allocation(self) -> Option<(NonNull<u8>, Layout, A)> {
+        let alloc = if self.table.is_empty_singleton() {
+            None
+        } else {
+            // Avoid `Option::unwrap_or_else` because it bloats LLVM IR.
+            let (layout, ctrl_offset) =
+                match Self::TABLE_LAYOUT.calculate_layout_for(self.table.buckets()) {
+                    Some(lco) => lco,
+                    None => unsafe { hint::unreachable_unchecked() },
+                };
+            Some((
+                unsafe { NonNull::new_unchecked(self.table.ctrl.as_ptr().sub(ctrl_offset)) },
+                layout,
+                unsafe { ptr::read(&self.alloc) },
+            ))
+        };
+        mem::forget(self);
+        alloc
+    }
+}
+
+unsafe impl<T, A: Allocator> Send for RawTable<T, A>
+where
+    T: Send,
+    A: Send,
+{
+}
+unsafe impl<T, A: Allocator> Sync for RawTable<T, A>
+where
+    T: Sync,
+    A: Sync,
+{
+}
+
+impl RawTableInner {
+    const NEW: Self = RawTableInner::new();
+
+    /// Creates a new empty hash table without allocating any memory.
+    ///
+    /// In effect this returns a table with exactly 1 bucket. However we can
+    /// leave the data pointer dangling since that bucket is never accessed
+    /// due to our load factor forcing us to always have at least 1 free bucket.
+    #[inline]
+    const fn new() -> Self {
+        Self {
+            // Be careful to cast the entire slice to a raw pointer.
+            ctrl: unsafe { NonNull::new_unchecked(Group::static_empty() as *const _ as *mut u8) },
+            bucket_mask: 0,
+            items: 0,
+            growth_left: 0,
+        }
+    }
+}
+
+impl RawTableInner {
+    /// Allocates a new [`RawTableInner`] with the given number of buckets.
+    /// The control bytes and buckets are left uninitialized.
+    ///
+    /// # Safety
+    ///
+    /// The caller of this function must ensure that the `buckets` is power of two
+    /// and also initialize all control bytes of the length `self.bucket_mask + 1 +
+    /// Group::WIDTH` with the [`EMPTY`] bytes.
+    ///
+    /// See also [`Allocator`] API for other safety concerns.
+    ///
+    /// [`Allocator`]: https://doc.rust-lang.org/alloc/alloc/trait.Allocator.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn new_uninitialized<A>(
+        alloc: &A,
+        table_layout: TableLayout,
+        buckets: usize,
+        fallibility: Fallibility,
+    ) -> Result<Self, TryReserveError>
+    where
+        A: Allocator,
+    {
+        debug_assert!(buckets.is_power_of_two());
+
+        // Avoid `Option::ok_or_else` because it bloats LLVM IR.
+        let (layout, ctrl_offset) = match table_layout.calculate_layout_for(buckets) {
+            Some(lco) => lco,
+            None => return Err(fallibility.capacity_overflow()),
+        };
+
+        let ptr: NonNull<u8> = match do_alloc(alloc, layout) {
+            Ok(block) => block.cast(),
+            Err(_) => return Err(fallibility.alloc_err(layout)),
+        };
+
+        // SAFETY: null pointer will be caught in above check
+        let ctrl = NonNull::new_unchecked(ptr.as_ptr().add(ctrl_offset));
+        Ok(Self {
+            ctrl,
+            bucket_mask: buckets - 1,
+            items: 0,
+            growth_left: bucket_mask_to_capacity(buckets - 1),
+        })
+    }
+
+    /// Attempts to allocate a new [`RawTableInner`] with at least enough
+    /// capacity for inserting the given number of elements without reallocating.
+    ///
+    /// All the control bytes are initialized with the [`EMPTY`] bytes.
+    #[inline]
+    fn fallible_with_capacity<A>(
+        alloc: &A,
+        table_layout: TableLayout,
+        capacity: usize,
+        fallibility: Fallibility,
+    ) -> Result<Self, TryReserveError>
+    where
+        A: Allocator,
+    {
+        if capacity == 0 {
+            Ok(Self::NEW)
+        } else {
+            // SAFETY: We checked that we could successfully allocate the new table, and then
+            // initialized all control bytes with the constant `EMPTY` byte.
+            unsafe {
+                let buckets =
+                    capacity_to_buckets(capacity).ok_or_else(|| fallibility.capacity_overflow())?;
+
+                let result = Self::new_uninitialized(alloc, table_layout, buckets, fallibility)?;
+                // SAFETY: We checked that the table is allocated and therefore the table already has
+                // `self.bucket_mask + 1 + Group::WIDTH` number of control bytes (see TableLayout::calculate_layout_for)
+                // so writing `self.num_ctrl_bytes() == bucket_mask + 1 + Group::WIDTH` bytes is safe.
+                result.ctrl(0).write_bytes(EMPTY, result.num_ctrl_bytes());
+
+                Ok(result)
+            }
+        }
+    }
+
+    /// Allocates a new [`RawTableInner`] with at least enough capacity for inserting
+    /// the given number of elements without reallocating.
+    ///
+    /// Panics if the new capacity exceeds [`isize::MAX`] bytes and [`abort`] the program
+    /// in case of allocation error. Use [`fallible_with_capacity`] instead if you want to
+    /// handle memory allocation failure.
+    ///
+    /// All the control bytes are initialized with the [`EMPTY`] bytes.
+    ///
+    /// [`fallible_with_capacity`]: RawTableInner::fallible_with_capacity
+    /// [`abort`]: https://doc.rust-lang.org/alloc/alloc/fn.handle_alloc_error.html
+    fn with_capacity<A>(alloc: &A, table_layout: TableLayout, capacity: usize) -> Self
+    where
+        A: Allocator,
+    {
+        // Avoid `Result::unwrap_or_else` because it bloats LLVM IR.
+        match Self::fallible_with_capacity(alloc, table_layout, capacity, Fallibility::Infallible) {
+            Ok(table_inner) => table_inner,
+            // SAFETY: All allocation errors will be caught inside `RawTableInner::new_uninitialized`.
+            Err(_) => unsafe { hint::unreachable_unchecked() },
+        }
+    }
+
+    /// Fixes up an insertion slot returned by the [`RawTableInner::find_insert_slot_in_group`] method.
+    ///
+    /// In tables smaller than the group width (`self.buckets() < Group::WIDTH`), trailing control
+    /// bytes outside the range of the table are filled with [`EMPTY`] entries. These will unfortunately
+    /// trigger a match of [`RawTableInner::find_insert_slot_in_group`] function. This is because
+    /// the `Some(bit)` returned by `group.match_empty_or_deleted().lowest_set_bit()` after masking
+    /// (`(probe_seq.pos + bit) & self.bucket_mask`) may point to a full bucket that is already occupied.
+    /// We detect this situation here and perform a second scan starting at the beginning of the table.
+    /// This second scan is guaranteed to find an empty slot (due to the load factor) before hitting the
+    /// trailing control bytes (containing [`EMPTY`] bytes).
+    ///
+    /// If this function is called correctly, it is guaranteed to return [`InsertSlot`] with an
+    /// index of an empty or deleted bucket in the range `0..self.buckets()` (see `Warning` and
+    /// `Safety`).
+    ///
+    /// # Warning
+    ///
+    /// The table must have at least 1 empty or deleted `bucket`, otherwise if the table is less than
+    /// the group width (`self.buckets() < Group::WIDTH`) this function returns an index outside of the
+    /// table indices range `0..self.buckets()` (`0..=self.bucket_mask`). Attempt to write data at that
+    /// index will cause immediate [`undefined behavior`].
+    ///
+    /// # Safety
+    ///
+    /// The safety rules are directly derived from the safety rules for [`RawTableInner::ctrl`] method.
+    /// Thus, in order to uphold those safety contracts, as well as for the correct logic of the work
+    /// of this crate, the following rules are necessary and sufficient:
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes otherwise calling this
+    ///   function results in [`undefined behavior`].
+    ///
+    /// * This function must only be used on insertion slots found by [`RawTableInner::find_insert_slot_in_group`]
+    ///   (after the `find_insert_slot_in_group` function, but before insertion into the table).
+    ///
+    /// * The `index` must not be greater than the `self.bucket_mask`, i.e. `(index + 1) <= self.buckets()`
+    ///   (this one is provided by the [`RawTableInner::find_insert_slot_in_group`] function).
+    ///
+    /// Calling this function with an index not provided by [`RawTableInner::find_insert_slot_in_group`]
+    /// may result in [`undefined behavior`] even if the index satisfies the safety rules of the
+    /// [`RawTableInner::ctrl`] function (`index < self.bucket_mask + 1 + Group::WIDTH`).
+    ///
+    /// [`RawTableInner::ctrl`]: RawTableInner::ctrl
+    /// [`RawTableInner::find_insert_slot_in_group`]: RawTableInner::find_insert_slot_in_group
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn fix_insert_slot(&self, mut index: usize) -> InsertSlot {
+        // SAFETY: The caller of this function ensures that `index` is in the range `0..=self.bucket_mask`.
+        if unlikely(self.is_bucket_full(index)) {
+            debug_assert!(self.bucket_mask < Group::WIDTH);
+            // SAFETY:
+            //
+            // * Since the caller of this function ensures that the control bytes are properly
+            //   initialized and `ptr = self.ctrl(0)` points to the start of the array of control
+            //   bytes, therefore: `ctrl` is valid for reads, properly aligned to `Group::WIDTH`
+            //   and points to the properly initialized control bytes (see also
+            //   `TableLayout::calculate_layout_for` and `ptr::read`);
+            //
+            // * Because the caller of this function ensures that the index was provided by the
+            //   `self.find_insert_slot_in_group()` function, so for for tables larger than the
+            //   group width (self.buckets() >= Group::WIDTH), we will never end up in the given
+            //   branch, since `(probe_seq.pos + bit) & self.bucket_mask` in `find_insert_slot_in_group`
+            //   cannot return a full bucket index. For tables smaller than the group width, calling
+            //   the `unwrap_unchecked` function is also safe, as the trailing control bytes outside
+            //   the range of the table are filled with EMPTY bytes (and we know for sure that there
+            //   is at least one FULL bucket), so this second scan either finds an empty slot (due to
+            //   the load factor) or hits the trailing control bytes (containing EMPTY).
+            index = Group::load_aligned(self.ctrl(0))
+                .match_empty_or_deleted()
+                .lowest_set_bit()
+                .unwrap_unchecked();
+        }
+        InsertSlot { index }
+    }
+
+    /// Finds the position to insert something in a group.
+    ///
+    /// **This may have false positives and must be fixed up with `fix_insert_slot`
+    /// before it's used.**
+    ///
+    /// The function is guaranteed to return the index of an empty or deleted [`Bucket`]
+    /// in the range `0..self.buckets()` (`0..=self.bucket_mask`).
+    #[inline]
+    fn find_insert_slot_in_group(&self, group: &Group, probe_seq: &ProbeSeq) -> Option<usize> {
+        let bit = group.match_empty_or_deleted().lowest_set_bit();
+
+        if likely(bit.is_some()) {
+            // This is the same as `(probe_seq.pos + bit) % self.buckets()` because the number
+            // of buckets is a power of two, and `self.bucket_mask = self.buckets() - 1`.
+            Some((probe_seq.pos + bit.unwrap()) & self.bucket_mask)
+        } else {
+            None
+        }
+    }
+
+    /// Searches for an element in the table, or a potential slot where that element could
+    /// be inserted (an empty or deleted [`Bucket`] index).
+    ///
+    /// This uses dynamic dispatch to reduce the amount of code generated, but that is
+    /// eliminated by LLVM optimizations.
+    ///
+    /// This function does not make any changes to the `data` part of the table, or any
+    /// changes to the `items` or `growth_left` field of the table.
+    ///
+    /// The table must have at least 1 empty or deleted `bucket`, otherwise, if the
+    /// `eq: &mut dyn FnMut(usize) -> bool` function does not return `true`, this function
+    /// will never return (will go into an infinite loop) for tables larger than the group
+    /// width, or return an index outside of the table indices range if the table is less
+    /// than the group width.
+    ///
+    /// This function is guaranteed to provide the `eq: &mut dyn FnMut(usize) -> bool`
+    /// function with only `FULL` buckets' indices and return the `index` of the found
+    /// element (as `Ok(index)`). If the element is not found and there is at least 1
+    /// empty or deleted [`Bucket`] in the table, the function is guaranteed to return
+    /// [InsertSlot] with an index in the range `0..self.buckets()`, but in any case,
+    /// if this function returns [`InsertSlot`], it will contain an index in the range
+    /// `0..=self.buckets()`.
+    ///
+    /// # Safety
+    ///
+    /// The [`RawTableInner`] must have properly initialized control bytes otherwise calling
+    /// this function results in [`undefined behavior`].
+    ///
+    /// Attempt to write data at the [`InsertSlot`] returned by this function when the table is
+    /// less than the group width and if there was not at least one empty or deleted bucket in
+    /// the table will cause immediate [`undefined behavior`]. This is because in this case the
+    /// function will return `self.bucket_mask + 1` as an index due to the trailing [`EMPTY]
+    /// control bytes outside the table range.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn find_or_find_insert_slot_inner(
+        &self,
+        hash: u64,
+        eq: &mut dyn FnMut(usize) -> bool,
+    ) -> Result<usize, InsertSlot> {
+        let mut insert_slot = None;
+
+        let h2_hash = h2(hash);
+        let mut probe_seq = self.probe_seq(hash);
+
+        loop {
+            // SAFETY:
+            // * Caller of this function ensures that the control bytes are properly initialized.
+            //
+            // * `ProbeSeq.pos` cannot be greater than `self.bucket_mask = self.buckets() - 1`
+            //   of the table due to masking with `self.bucket_mask` and also because mumber of
+            //   buckets is a power of two (see `self.probe_seq` function).
+            //
+            // * Even if `ProbeSeq.pos` returns `position == self.bucket_mask`, it is safe to
+            //   call `Group::load` due to the extended control bytes range, which is
+            //  `self.bucket_mask + 1 + Group::WIDTH` (in fact, this means that the last control
+            //   byte will never be read for the allocated table);
+            //
+            // * Also, even if `RawTableInner` is not already allocated, `ProbeSeq.pos` will
+            //   always return "0" (zero), so Group::load will read unaligned `Group::static_empty()`
+            //   bytes, which is safe (see RawTableInner::new).
+            let group = unsafe { Group::load(self.ctrl(probe_seq.pos)) };
+
+            for bit in group.match_byte(h2_hash) {
+                let index = (probe_seq.pos + bit) & self.bucket_mask;
+
+                if likely(eq(index)) {
+                    return Ok(index);
+                }
+            }
+
+            // We didn't find the element we were looking for in the group, try to get an
+            // insertion slot from the group if we don't have one yet.
+            if likely(insert_slot.is_none()) {
+                insert_slot = self.find_insert_slot_in_group(&group, &probe_seq);
+            }
+
+            // Only stop the search if the group contains at least one empty element.
+            // Otherwise, the element that we are looking for might be in a following group.
+            if likely(group.match_empty().any_bit_set()) {
+                // We must have found a insert slot by now, since the current group contains at
+                // least one. For tables smaller than the group width, there will still be an
+                // empty element in the current (and only) group due to the load factor.
+                unsafe {
+                    // SAFETY:
+                    // * Caller of this function ensures that the control bytes are properly initialized.
+                    //
+                    // * We use this function with the slot / index found by `self.find_insert_slot_in_group`
+                    return Err(self.fix_insert_slot(insert_slot.unwrap_unchecked()));
+                }
+            }
+
+            probe_seq.move_next(self.bucket_mask);
+        }
+    }
+
+    /// Searches for an empty or deleted bucket which is suitable for inserting a new
+    /// element and sets the hash for that slot. Returns an index of that slot and the
+    /// old control byte stored in the found index.
+    ///
+    /// This function does not check if the given element exists in the table. Also,
+    /// this function does not check if there is enough space in the table to insert
+    /// a new element. Caller of the funtion must make ensure that the table has at
+    /// least 1 empty or deleted `bucket`, otherwise this function will never return
+    /// (will go into an infinite loop) for tables larger than the group width, or
+    /// return an index outside of the table indices range if the table is less than
+    /// the group width.
+    ///
+    /// If there is at least 1 empty or deleted `bucket` in the table, the function is
+    /// guaranteed to return an `index` in the range `0..self.buckets()`, but in any case,
+    /// if this function returns an `index` it will be in the range `0..=self.buckets()`.
+    ///
+    /// This function does not make any changes to the `data` parts of the table,
+    /// or any changes to the the `items` or `growth_left` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// The safety rules are directly derived from the safety rules for the
+    /// [`RawTableInner::set_ctrl_h2`] and [`RawTableInner::find_insert_slot`] methods.
+    /// Thus, in order to uphold the safety contracts for that methods, as well as for
+    /// the correct logic of the work of this crate, you must observe the following rules
+    /// when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated and has properly initialized
+    ///   control bytes otherwise calling this function results in [`undefined behavior`].
+    ///
+    /// * The caller of this function must ensure that the "data" parts of the table
+    ///   will have an entry in the returned index (matching the given hash) right
+    ///   after calling this function.
+    ///
+    /// Attempt to write data at the `index` returned by this function when the table is
+    /// less than the group width and if there was not at least one empty or deleted bucket in
+    /// the table will cause immediate [`undefined behavior`]. This is because in this case the
+    /// function will return `self.bucket_mask + 1` as an index due to the trailing [`EMPTY]
+    /// control bytes outside the table range.
+    ///
+    /// The caller must independently increase the `items` field of the table, and also,
+    /// if the old control byte was [`EMPTY`], then decrease the table's `growth_left`
+    /// field, and do not change it if the old control byte was [`DELETED`].
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    /// [`RawTableInner::ctrl`]: RawTableInner::ctrl
+    /// [`RawTableInner::set_ctrl_h2`]: RawTableInner::set_ctrl_h2
+    /// [`RawTableInner::find_insert_slot`]: RawTableInner::find_insert_slot
+    #[inline]
+    unsafe fn prepare_insert_slot(&mut self, hash: u64) -> (usize, u8) {
+        // SAFETY: Caller of this function ensures that the control bytes are properly initialized.
+        let index: usize = self.find_insert_slot(hash).index;
+        // SAFETY:
+        // 1. The `find_insert_slot` function either returns an `index` less than or
+        //    equal to `self.buckets() = self.bucket_mask + 1` of the table, or never
+        //    returns if it cannot find an empty or deleted slot.
+        // 2. The caller of this function guarantees that the table has already been
+        //    allocated
+        let old_ctrl = *self.ctrl(index);
+        self.set_ctrl_h2(index, hash);
+        (index, old_ctrl)
+    }
+
+    /// Searches for an empty or deleted bucket which is suitable for inserting
+    /// a new element, returning the `index` for the new [`Bucket`].
+    ///
+    /// This function does not make any changes to the `data` part of the table, or any
+    /// changes to the `items` or `growth_left` field of the table.
+    ///
+    /// The table must have at least 1 empty or deleted `bucket`, otherwise this function
+    /// will never return (will go into an infinite loop) for tables larger than the group
+    /// width, or return an index outside of the table indices range if the table is less
+    /// than the group width.
+    ///
+    /// If there is at least 1 empty or deleted `bucket` in the table, the function is
+    /// guaranteed to return [`InsertSlot`] with an index in the range `0..self.buckets()`,
+    /// but in any case, if this function returns [`InsertSlot`], it will contain an index
+    /// in the range `0..=self.buckets()`.
+    ///
+    /// # Safety
+    ///
+    /// The [`RawTableInner`] must have properly initialized control bytes otherwise calling
+    /// this function results in [`undefined behavior`].
+    ///
+    /// Attempt to write data at the [`InsertSlot`] returned by this function when the table is
+    /// less than the group width and if there was not at least one empty or deleted bucket in
+    /// the table will cause immediate [`undefined behavior`]. This is because in this case the
+    /// function will return `self.bucket_mask + 1` as an index due to the trailing [`EMPTY]
+    /// control bytes outside the table range.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn find_insert_slot(&self, hash: u64) -> InsertSlot {
+        let mut probe_seq = self.probe_seq(hash);
+        loop {
+            // SAFETY:
+            // * Caller of this function ensures that the control bytes are properly initialized.
+            //
+            // * `ProbeSeq.pos` cannot be greater than `self.bucket_mask = self.buckets() - 1`
+            //   of the table due to masking with `self.bucket_mask` and also because mumber of
+            //   buckets is a power of two (see `self.probe_seq` function).
+            //
+            // * Even if `ProbeSeq.pos` returns `position == self.bucket_mask`, it is safe to
+            //   call `Group::load` due to the extended control bytes range, which is
+            //  `self.bucket_mask + 1 + Group::WIDTH` (in fact, this means that the last control
+            //   byte will never be read for the allocated table);
+            //
+            // * Also, even if `RawTableInner` is not already allocated, `ProbeSeq.pos` will
+            //   always return "0" (zero), so Group::load will read unaligned `Group::static_empty()`
+            //   bytes, which is safe (see RawTableInner::new).
+            let group = unsafe { Group::load(self.ctrl(probe_seq.pos)) };
+
+            let index = self.find_insert_slot_in_group(&group, &probe_seq);
+            if likely(index.is_some()) {
+                // SAFETY:
+                // * Caller of this function ensures that the control bytes are properly initialized.
+                //
+                // * We use this function with the slot / index found by `self.find_insert_slot_in_group`
+                unsafe {
+                    return self.fix_insert_slot(index.unwrap_unchecked());
+                }
+            }
+            probe_seq.move_next(self.bucket_mask);
+        }
+    }
+
+    /// Searches for an element in a table, returning the `index` of the found element.
+    /// This uses dynamic dispatch to reduce the amount of code generated, but it is
+    /// eliminated by LLVM optimizations.
+    ///
+    /// This function does not make any changes to the `data` part of the table, or any
+    /// changes to the `items` or `growth_left` field of the table.
+    ///
+    /// The table must have at least 1 empty `bucket`, otherwise, if the
+    /// `eq: &mut dyn FnMut(usize) -> bool` function does not return `true`,
+    /// this function will also never return (will go into an infinite loop).
+    ///
+    /// This function is guaranteed to provide the `eq: &mut dyn FnMut(usize) -> bool`
+    /// function with only `FULL` buckets' indices and return the `index` of the found
+    /// element as `Some(index)`, so the index will always be in the range
+    /// `0..self.buckets()`.
+    ///
+    /// # Safety
+    ///
+    /// The [`RawTableInner`] must have properly initialized control bytes otherwise calling
+    /// this function results in [`undefined behavior`].
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline(always)]
+    unsafe fn find_inner(&self, hash: u64, eq: &mut dyn FnMut(usize) -> bool) -> Option<usize> {
+        let h2_hash = h2(hash);
+        let mut probe_seq = self.probe_seq(hash);
+
+        loop {
+            // SAFETY:
+            // * Caller of this function ensures that the control bytes are properly initialized.
+            //
+            // * `ProbeSeq.pos` cannot be greater than `self.bucket_mask = self.buckets() - 1`
+            //   of the table due to masking with `self.bucket_mask`.
+            //
+            // * Even if `ProbeSeq.pos` returns `position == self.bucket_mask`, it is safe to
+            //   call `Group::load` due to the extended control bytes range, which is
+            //  `self.bucket_mask + 1 + Group::WIDTH` (in fact, this means that the last control
+            //   byte will never be read for the allocated table);
+            //
+            // * Also, even if `RawTableInner` is not already allocated, `ProbeSeq.pos` will
+            //   always return "0" (zero), so Group::load will read unaligned `Group::static_empty()`
+            //   bytes, which is safe (see RawTableInner::new_in).
+            let group = unsafe { Group::load(self.ctrl(probe_seq.pos)) };
+
+            for bit in group.match_byte(h2_hash) {
+                // This is the same as `(probe_seq.pos + bit) % self.buckets()` because the number
+                // of buckets is a power of two, and `self.bucket_mask = self.buckets() - 1`.
+                let index = (probe_seq.pos + bit) & self.bucket_mask;
+
+                if likely(eq(index)) {
+                    return Some(index);
+                }
+            }
+
+            if likely(group.match_empty().any_bit_set()) {
+                return None;
+            }
+
+            probe_seq.move_next(self.bucket_mask);
+        }
+    }
+
+    /// Prepares for rehashing data in place (that is, without allocating new memory).
+    /// Converts all full index `control bytes` to `DELETED` and all `DELETED` control
+    /// bytes to `EMPTY`, i.e. performs the following conversion:
+    ///
+    /// - `EMPTY` control bytes   -> `EMPTY`;
+    /// - `DELETED` control bytes -> `EMPTY`;
+    /// - `FULL` control bytes    -> `DELETED`.
+    ///
+    /// This function does not make any changes to the `data` parts of the table,
+    /// or any changes to the the `items` or `growth_left` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// You must observe the following safety rules when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The caller of this function must convert the `DELETED` bytes back to `FULL`
+    ///   bytes when re-inserting them into their ideal position (which was impossible
+    ///   to do during the first insert due to tombstones). If the caller does not do
+    ///   this, then calling this function may result in a memory leak.
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes otherwise
+    ///   calling this function results in [`undefined behavior`].
+    ///
+    /// Calling this function on a table that has not been allocated results in
+    /// [`undefined behavior`].
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[allow(clippy::mut_mut)]
+    #[inline]
+    unsafe fn prepare_rehash_in_place(&mut self) {
+        // Bulk convert all full control bytes to DELETED, and all DELETED control bytes to EMPTY.
+        // This effectively frees up all buckets containing a DELETED entry.
+        //
+        // SAFETY:
+        // 1. `i` is guaranteed to be within bounds since we are iterating from zero to `buckets - 1`;
+        // 2. Even if `i` will be `i == self.bucket_mask`, it is safe to call `Group::load_aligned`
+        //    due to the extended control bytes range, which is `self.bucket_mask + 1 + Group::WIDTH`;
+        // 3. The caller of this function guarantees that [`RawTableInner`] has already been allocated;
+        // 4. We can use `Group::load_aligned` and `Group::store_aligned` here since we start from 0
+        //    and go to the end with a step equal to `Group::WIDTH` (see TableLayout::calculate_layout_for).
+        for i in (0..self.buckets()).step_by(Group::WIDTH) {
+            let group = Group::load_aligned(self.ctrl(i));
+            let group = group.convert_special_to_empty_and_full_to_deleted();
+            group.store_aligned(self.ctrl(i));
+        }
+
+        // Fix up the trailing control bytes. See the comments in set_ctrl
+        // for the handling of tables smaller than the group width.
+        //
+        // SAFETY: The caller of this function guarantees that [`RawTableInner`]
+        // has already been allocated
+        if unlikely(self.buckets() < Group::WIDTH) {
+            // SAFETY: We have `self.bucket_mask + 1 + Group::WIDTH` number of control bytes,
+            // so copying `self.buckets() == self.bucket_mask + 1` bytes with offset equal to
+            // `Group::WIDTH` is safe
+            self.ctrl(0)
+                .copy_to(self.ctrl(Group::WIDTH), self.buckets());
+        } else {
+            // SAFETY: We have `self.bucket_mask + 1 + Group::WIDTH` number of
+            // control bytes,so copying `Group::WIDTH` bytes with offset equal
+            // to `self.buckets() == self.bucket_mask + 1` is safe
+            self.ctrl(0)
+                .copy_to(self.ctrl(self.buckets()), Group::WIDTH);
+        }
+    }
+
+    /// Returns an iterator over every element in the table.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result
+    /// is [`undefined behavior`]:
+    ///
+    /// * The caller has to ensure that the `RawTableInner` outlives the
+    ///   `RawIter`. Because we cannot make the `next` method unsafe on
+    ///   the `RawIter` struct, we have to make the `iter` method unsafe.
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn iter<T>(&self) -> RawIter<T> {
+        // SAFETY:
+        // 1. Since the caller of this function ensures that the control bytes
+        //    are properly initialized and `self.data_end()` points to the start
+        //    of the array of control bytes, therefore: `ctrl` is valid for reads,
+        //    properly aligned to `Group::WIDTH` and points to the properly initialized
+        //    control bytes.
+        // 2. `data` bucket index in the table is equal to the `ctrl` index (i.e.
+        //    equal to zero).
+        // 3. We pass the exact value of buckets of the table to the function.
+        //
+        //                         `ctrl` points here (to the start
+        //                         of the first control byte `CT0`)
+        //                          ∨
+        // [Pad], T_n, ..., T1, T0, |CT0, CT1, ..., CT_n|, Group::WIDTH
+        //                           \________  ________/
+        //                                    \/
+        //       `n = buckets - 1`, i.e. `RawIndexTableInner::buckets() - 1`
+        //
+        // where: T0...T_n  - our stored data;
+        //        CT0...CT_n - control bytes or metadata for `data`.
+        let data = Bucket::from_base_index(self.data_end(), 0);
+        RawIter {
+            // SAFETY: See explanation above
+            iter: RawIterRange::new(self.ctrl.as_ptr(), data, self.buckets()),
+            items: self.items,
+        }
+    }
+
+    /// Executes the destructors (if any) of the values stored in the table.
+    ///
+    /// # Note
+    ///
+    /// This function does not erase the control bytes of the table and does
+    /// not make any changes to the `items` or `growth_left` fields of the
+    /// table. If necessary, the caller of this function must manually set
+    /// up these table fields, for example using the [`clear_no_drop`] function.
+    ///
+    /// Be careful during calling this function, because drop function of
+    /// the elements can panic, and this can leave table in an inconsistent
+    /// state.
+    ///
+    /// # Safety
+    ///
+    /// If `T` is a type that should be dropped and **the table is not empty**,
+    /// calling this function more than once results in [`undefined behavior`].
+    ///
+    /// If `T` is not [`Copy`], attempting to use values stored in the table after
+    /// calling this function may result in [`undefined behavior`].
+    ///
+    /// It is safe to call this function on a table that has not been allocated,
+    /// on a table with uninitialized control bytes, and on a table with no actual
+    /// data but with `Full` control bytes if `self.items == 0`.
+    ///
+    /// See also [`Bucket::drop`] / [`Bucket::as_ptr`] methods, for more information
+    /// about of properly removing or saving `element` from / into the [`RawTable`] /
+    /// [`RawTableInner`].
+    ///
+    /// [`Bucket::drop`]: Bucket::drop
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`clear_no_drop`]: RawTableInner::clear_no_drop
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    unsafe fn drop_elements<T>(&mut self) {
+        // Check that `self.items != 0`. Protects against the possibility
+        // of creating an iterator on an table with uninitialized control bytes.
+        if T::NEEDS_DROP && self.items != 0 {
+            // SAFETY: We know for sure that RawTableInner will outlive the
+            // returned `RawIter` iterator, and the caller of this function
+            // must uphold the safety contract for `drop_elements` method.
+            for item in self.iter::<T>() {
+                // SAFETY: The caller must uphold the safety contract for
+                // `drop_elements` method.
+                item.drop();
+            }
+        }
+    }
+
+    /// Executes the destructors (if any) of the values stored in the table and than
+    /// deallocates the table.
+    ///
+    /// # Note
+    ///
+    /// Calling this function automatically makes invalid (dangling) all instances of
+    /// buckets ([`Bucket`]) and makes invalid (dangling) the `ctrl` field of the table.
+    ///
+    /// This function does not make any changes to the `bucket_mask`, `items` or `growth_left`
+    /// fields of the table. If necessary, the caller of this function must manually set
+    /// up these table fields.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is [`undefined behavior`]:
+    ///
+    /// * Calling this function more than once;
+    ///
+    /// * The `alloc` must be the same [`Allocator`] as the `Allocator` that was used
+    ///   to allocate this table.
+    ///
+    /// * The `table_layout` must be the same [`TableLayout`] as the `TableLayout` that
+    ///   was used to allocate this table.
+    ///
+    /// The caller of this function should pay attention to the possibility of the
+    /// elements' drop function panicking, because this:
+    ///
+    ///    * May leave the table in an inconsistent state;
+    ///
+    ///    * Memory is never deallocated, so a memory leak may occur.
+    ///
+    /// Attempt to use the `ctrl` field of the table (dereference) after calling this
+    /// function results in [`undefined behavior`].
+    ///
+    /// It is safe to call this function on a table that has not been allocated,
+    /// on a table with uninitialized control bytes, and on a table with no actual
+    /// data but with `Full` control bytes if `self.items == 0`.
+    ///
+    /// See also [`RawTableInner::drop_elements`] or [`RawTableInner::free_buckets`]
+    /// for more  information.
+    ///
+    /// [`RawTableInner::drop_elements`]: RawTableInner::drop_elements
+    /// [`RawTableInner::free_buckets`]: RawTableInner::free_buckets
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    unsafe fn drop_inner_table<T, A: Allocator>(&mut self, alloc: &A, table_layout: TableLayout) {
+        if !self.is_empty_singleton() {
+            unsafe {
+                // SAFETY: The caller must uphold the safety contract for `drop_inner_table` method.
+                self.drop_elements::<T>();
+                // SAFETY:
+                // 1. We have checked that our table is allocated.
+                // 2. The caller must uphold the safety contract for `drop_inner_table` method.
+                self.free_buckets(alloc, table_layout);
+            }
+        }
+    }
+
+    #[inline]
+    unsafe fn bucket<T>(&self, index: usize) -> Bucket<T> {
+        debug_assert_ne!(self.bucket_mask, 0);
+        debug_assert!(index < self.buckets());
+        Bucket::from_base_index(self.data_end(), index)
+    }
+
+    #[inline]
+    unsafe fn bucket_ptr(&self, index: usize, size_of: usize) -> *mut u8 {
+        debug_assert_ne!(self.bucket_mask, 0);
+        debug_assert!(index < self.buckets());
+        let base: *mut u8 = self.data_end().as_ptr();
+        base.sub((index + 1) * size_of)
+    }
+
+    #[inline]
+    unsafe fn data_end<T>(&self) -> NonNull<T> {
+        NonNull::new_unchecked(self.ctrl.as_ptr().cast())
+    }
+
+    /// Returns an iterator-like object for a probe sequence on the table.
+    ///
+    /// This iterator never terminates, but is guaranteed to visit each bucket
+    /// group exactly once. The loop using `probe_seq` must terminate upon
+    /// reaching a group containing an empty bucket.
+    #[inline]
+    fn probe_seq(&self, hash: u64) -> ProbeSeq {
+        ProbeSeq {
+            // This is the same as `hash as usize % self.buckets()` because the number
+            // of buckets is a power of two, and `self.bucket_mask = self.buckets() - 1`.
+            pos: h1(hash) & self.bucket_mask,
+            stride: 0,
+        }
+    }
+
+    /// Returns the index of a bucket for which a value must be inserted if there is enough rooom
+    /// in the table, otherwise returns error
+    #[cfg(feature = "raw")]
+    #[inline]
+    unsafe fn prepare_insert_no_grow(&mut self, hash: u64) -> Result<usize, ()> {
+        let index = self.find_insert_slot(hash).index;
+        let old_ctrl = *self.ctrl(index);
+        if unlikely(self.growth_left == 0 && special_is_empty(old_ctrl)) {
+            Err(())
+        } else {
+            self.record_item_insert_at(index, old_ctrl, hash);
+            Ok(index)
+        }
+    }
+
+    #[inline]
+    unsafe fn record_item_insert_at(&mut self, index: usize, old_ctrl: u8, hash: u64) {
+        self.growth_left -= usize::from(special_is_empty(old_ctrl));
+        self.set_ctrl_h2(index, hash);
+        self.items += 1;
+    }
+
+    #[inline]
+    fn is_in_same_group(&self, i: usize, new_i: usize, hash: u64) -> bool {
+        let probe_seq_pos = self.probe_seq(hash).pos;
+        let probe_index =
+            |pos: usize| (pos.wrapping_sub(probe_seq_pos) & self.bucket_mask) / Group::WIDTH;
+        probe_index(i) == probe_index(new_i)
+    }
+
+    /// Sets a control byte to the hash, and possibly also the replicated control byte at
+    /// the end of the array.
+    ///
+    /// This function does not make any changes to the `data` parts of the table,
+    /// or any changes to the the `items` or `growth_left` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// The safety rules are directly derived from the safety rules for [`RawTableInner::set_ctrl`]
+    /// method. Thus, in order to uphold the safety contracts for the method, you must observe the
+    /// following rules when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The `index` must not be greater than the `RawTableInner.bucket_mask`, i.e.
+    ///   `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)` must
+    ///   be no greater than the number returned by the function [`RawTableInner::buckets`].
+    ///
+    /// Calling this function on a table that has not been allocated results in [`undefined behavior`].
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`RawTableInner::set_ctrl`]: RawTableInner::set_ctrl
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn set_ctrl_h2(&mut self, index: usize, hash: u64) {
+        // SAFETY: The caller must uphold the safety rules for the [`RawTableInner::set_ctrl_h2`]
+        self.set_ctrl(index, h2(hash));
+    }
+
+    /// Replaces the hash in the control byte at the given index with the provided one,
+    /// and possibly also replicates the new control byte at the end of the array of control
+    /// bytes, returning the old control byte.
+    ///
+    /// This function does not make any changes to the `data` parts of the table,
+    /// or any changes to the the `items` or `growth_left` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// The safety rules are directly derived from the safety rules for [`RawTableInner::set_ctrl_h2`]
+    /// and [`RawTableInner::ctrl`] methods. Thus, in order to uphold the safety contracts for both
+    /// methods, you must observe the following rules when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The `index` must not be greater than the `RawTableInner.bucket_mask`, i.e.
+    ///   `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)` must
+    ///   be no greater than the number returned by the function [`RawTableInner::buckets`].
+    ///
+    /// Calling this function on a table that has not been allocated results in [`undefined behavior`].
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`RawTableInner::set_ctrl_h2`]: RawTableInner::set_ctrl_h2
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn replace_ctrl_h2(&mut self, index: usize, hash: u64) -> u8 {
+        // SAFETY: The caller must uphold the safety rules for the [`RawTableInner::replace_ctrl_h2`]
+        let prev_ctrl = *self.ctrl(index);
+        self.set_ctrl_h2(index, hash);
+        prev_ctrl
+    }
+
+    /// Sets a control byte, and possibly also the replicated control byte at
+    /// the end of the array.
+    ///
+    /// This function does not make any changes to the `data` parts of the table,
+    /// or any changes to the the `items` or `growth_left` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// You must observe the following safety rules when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The `index` must not be greater than the `RawTableInner.bucket_mask`, i.e.
+    ///   `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)` must
+    ///   be no greater than the number returned by the function [`RawTableInner::buckets`].
+    ///
+    /// Calling this function on a table that has not been allocated results in [`undefined behavior`].
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn set_ctrl(&mut self, index: usize, ctrl: u8) {
+        // Replicate the first Group::WIDTH control bytes at the end of
+        // the array without using a branch. If the tables smaller than
+        // the group width (self.buckets() < Group::WIDTH),
+        // `index2 = Group::WIDTH + index`, otherwise `index2` is:
+        //
+        // - If index >= Group::WIDTH then index == index2.
+        // - Otherwise index2 == self.bucket_mask + 1 + index.
+        //
+        // The very last replicated control byte is never actually read because
+        // we mask the initial index for unaligned loads, but we write it
+        // anyways because it makes the set_ctrl implementation simpler.
+        //
+        // If there are fewer buckets than Group::WIDTH then this code will
+        // replicate the buckets at the end of the trailing group. For example
+        // with 2 buckets and a group size of 4, the control bytes will look
+        // like this:
+        //
+        //     Real    |             Replicated
+        // ---------------------------------------------
+        // | [A] | [B] | [EMPTY] | [EMPTY] | [A] | [B] |
+        // ---------------------------------------------
+
+        // This is the same as `(index.wrapping_sub(Group::WIDTH)) % self.buckets() + Group::WIDTH`
+        // because the number of buckets is a power of two, and `self.bucket_mask = self.buckets() - 1`.
+        let index2 = ((index.wrapping_sub(Group::WIDTH)) & self.bucket_mask) + Group::WIDTH;
+
+        // SAFETY: The caller must uphold the safety rules for the [`RawTableInner::set_ctrl`]
+        *self.ctrl(index) = ctrl;
+        *self.ctrl(index2) = ctrl;
+    }
+
+    /// Returns a pointer to a control byte.
+    ///
+    /// # Safety
+    ///
+    /// For the allocated [`RawTableInner`], the result is [`Undefined Behavior`],
+    /// if the `index` is greater than the `self.bucket_mask + 1 + Group::WIDTH`.
+    /// In that case, calling this function with `index == self.bucket_mask + 1 + Group::WIDTH`
+    /// will return a pointer to the end of the allocated table and it is useless on its own.
+    ///
+    /// Calling this function with `index >= self.bucket_mask + 1 + Group::WIDTH` on a
+    /// table that has not been allocated results in [`Undefined Behavior`].
+    ///
+    /// So to satisfy both requirements you should always follow the rule that
+    /// `index < self.bucket_mask + 1 + Group::WIDTH`
+    ///
+    /// Calling this function on [`RawTableInner`] that are not already allocated is safe
+    /// for read-only purpose.
+    ///
+    /// See also [`Bucket::as_ptr()`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`Bucket::as_ptr()`]: Bucket::as_ptr()
+    /// [`Undefined Behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn ctrl(&self, index: usize) -> *mut u8 {
+        debug_assert!(index < self.num_ctrl_bytes());
+        // SAFETY: The caller must uphold the safety rules for the [`RawTableInner::ctrl`]
+        self.ctrl.as_ptr().add(index)
+    }
+
+    #[inline]
+    fn buckets(&self) -> usize {
+        self.bucket_mask + 1
+    }
+
+    /// Checks whether the bucket at `index` is full.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure `index` is less than the number of buckets.
+    #[inline]
+    unsafe fn is_bucket_full(&self, index: usize) -> bool {
+        debug_assert!(index < self.buckets());
+        is_full(*self.ctrl(index))
+    }
+
+    #[inline]
+    fn num_ctrl_bytes(&self) -> usize {
+        self.bucket_mask + 1 + Group::WIDTH
+    }
+
+    #[inline]
+    fn is_empty_singleton(&self) -> bool {
+        self.bucket_mask == 0
+    }
+
+    /// Attempts to allocate a new hash table with at least enough capacity
+    /// for inserting the given number of elements without reallocating,
+    /// and return it inside ScopeGuard to protect against panic in the hash
+    /// function.
+    ///
+    /// # Note
+    ///
+    /// It is recommended (but not required):
+    ///
+    /// * That the new table's `capacity` be greater than or equal to `self.items`.
+    ///
+    /// * The `alloc` is the same [`Allocator`] as the `Allocator` used
+    ///   to allocate this table.
+    ///
+    /// * The `table_layout` is the same [`TableLayout`] as the `TableLayout` used
+    ///   to allocate this table.
+    ///
+    /// If `table_layout` does not match the `TableLayout` that was used to allocate
+    /// this table, then using `mem::swap` with the `self` and the new table returned
+    /// by this function results in [`undefined behavior`].
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[allow(clippy::mut_mut)]
+    #[inline]
+    fn prepare_resize<'a, A>(
+        &self,
+        alloc: &'a A,
+        table_layout: TableLayout,
+        capacity: usize,
+        fallibility: Fallibility,
+    ) -> Result<crate::scopeguard::ScopeGuard<Self, impl FnMut(&mut Self) + 'a>, TryReserveError>
+    where
+        A: Allocator,
+    {
+        debug_assert!(self.items <= capacity);
+
+        // Allocate and initialize the new table.
+        let new_table =
+            RawTableInner::fallible_with_capacity(alloc, table_layout, capacity, fallibility)?;
+
+        // The hash function may panic, in which case we simply free the new
+        // table without dropping any elements that may have been copied into
+        // it.
+        //
+        // This guard is also used to free the old table on success, see
+        // the comment at the bottom of this function.
+        Ok(guard(new_table, move |self_| {
+            if !self_.is_empty_singleton() {
+                // SAFETY:
+                // 1. We have checked that our table is allocated.
+                // 2. We know for sure that the `alloc` and `table_layout` matches the
+                //    [`Allocator`] and [`TableLayout`] used to allocate this table.
+                unsafe { self_.free_buckets(alloc, table_layout) };
+            }
+        }))
+    }
+
+    /// Reserves or rehashes to make room for `additional` more elements.
+    ///
+    /// This uses dynamic dispatch to reduce the amount of
+    /// code generated, but it is eliminated by LLVM optimizations when inlined.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is
+    /// [`undefined behavior`]:
+    ///
+    /// * The `alloc` must be the same [`Allocator`] as the `Allocator` used
+    ///   to allocate this table.
+    ///
+    /// * The `layout` must be the same [`TableLayout`] as the `TableLayout`
+    ///   used to allocate this table.
+    ///
+    /// * The `drop` function (`fn(*mut u8)`) must be the actual drop function of
+    ///   the elements stored in the table.
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[allow(clippy::inline_always)]
+    #[inline(always)]
+    unsafe fn reserve_rehash_inner<A>(
+        &mut self,
+        alloc: &A,
+        additional: usize,
+        hasher: &dyn Fn(&mut Self, usize) -> u64,
+        fallibility: Fallibility,
+        layout: TableLayout,
+        drop: Option<fn(*mut u8)>,
+    ) -> Result<(), TryReserveError>
+    where
+        A: Allocator,
+    {
+        // Avoid `Option::ok_or_else` because it bloats LLVM IR.
+        let new_items = match self.items.checked_add(additional) {
+            Some(new_items) => new_items,
+            None => return Err(fallibility.capacity_overflow()),
+        };
+        let full_capacity = bucket_mask_to_capacity(self.bucket_mask);
+        if new_items <= full_capacity / 2 {
+            // Rehash in-place without re-allocating if we have plenty of spare
+            // capacity that is locked up due to DELETED entries.
+
+            // SAFETY:
+            // 1. We know for sure that `[`RawTableInner`]` has already been allocated
+            //    (since new_items <= full_capacity / 2);
+            // 2. The caller ensures that `drop` function is the actual drop function of
+            //    the elements stored in the table.
+            // 3. The caller ensures that `layout` matches the [`TableLayout`] that was
+            //    used to allocate this table.
+            // 4. The caller ensures that the control bytes of the `RawTableInner`
+            //    are already initialized.
+            self.rehash_in_place(hasher, layout.size, drop);
+            Ok(())
+        } else {
+            // Otherwise, conservatively resize to at least the next size up
+            // to avoid churning deletes into frequent rehashes.
+            //
+            // SAFETY:
+            // 1. We know for sure that `capacity >= self.items`.
+            // 2. The caller ensures that `alloc` and `layout` matches the [`Allocator`] and
+            //    [`TableLayout`] that were used to allocate this table.
+            // 3. The caller ensures that the control bytes of the `RawTableInner`
+            //    are already initialized.
+            self.resize_inner(
+                alloc,
+                usize::max(new_items, full_capacity + 1),
+                hasher,
+                fallibility,
+                layout,
+            )
+        }
+    }
+
+    /// Returns an iterator over full buckets indices in the table.
+    ///
+    /// # Safety
+    ///
+    /// Behavior is undefined if any of the following conditions are violated:
+    ///
+    /// * The caller has to ensure that the `RawTableInner` outlives the
+    ///   `FullBucketsIndices`. Because we cannot make the `next` method
+    ///   unsafe on the `FullBucketsIndices` struct, we have to make the
+    ///   `full_buckets_indices` method unsafe.
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes.
+    #[inline(always)]
+    unsafe fn full_buckets_indices(&self) -> FullBucketsIndices {
+        // SAFETY:
+        // 1. Since the caller of this function ensures that the control bytes
+        //    are properly initialized and `self.ctrl(0)` points to the start
+        //    of the array of control bytes, therefore: `ctrl` is valid for reads,
+        //    properly aligned to `Group::WIDTH` and points to the properly initialized
+        //    control bytes.
+        // 2. The value of `items` is equal to the amount of data (values) added
+        //    to the table.
+        //
+        //                         `ctrl` points here (to the start
+        //                         of the first control byte `CT0`)
+        //                          ∨
+        // [Pad], T_n, ..., T1, T0, |CT0, CT1, ..., CT_n|, Group::WIDTH
+        //                           \________  ________/
+        //                                    \/
+        //       `n = buckets - 1`, i.e. `RawIndexTableInner::buckets() - 1`
+        //
+        // where: T0...T_n  - our stored data;
+        //        CT0...CT_n - control bytes or metadata for `data`.
+        let ctrl = NonNull::new_unchecked(self.ctrl(0));
+
+        FullBucketsIndices {
+            // Load the first group
+            // SAFETY: See explanation above.
+            current_group: Group::load_aligned(ctrl.as_ptr()).match_full().into_iter(),
+            group_first_index: 0,
+            ctrl,
+            items: self.items,
+        }
+    }
+
+    /// Allocates a new table of a different size and moves the contents of the
+    /// current table into it.
+    ///
+    /// This uses dynamic dispatch to reduce the amount of
+    /// code generated, but it is eliminated by LLVM optimizations when inlined.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is
+    /// [`undefined behavior`]:
+    ///
+    /// * The `alloc` must be the same [`Allocator`] as the `Allocator` used
+    ///   to allocate this table;
+    ///
+    /// * The `layout` must be the same [`TableLayout`] as the `TableLayout`
+    ///   used to allocate this table;
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes.
+    ///
+    /// The caller of this function must ensure that `capacity >= self.items`
+    /// otherwise:
+    ///
+    /// * If `self.items != 0`, calling of this function with `capacity == 0`
+    ///   results in [`undefined behavior`].
+    ///
+    /// * If `capacity_to_buckets(capacity) < Group::WIDTH` and
+    ///   `self.items > capacity_to_buckets(capacity)` calling this function
+    ///   results in [`undefined behavior`].
+    ///
+    /// * If `capacity_to_buckets(capacity) >= Group::WIDTH` and
+    ///   `self.items > capacity_to_buckets(capacity)` calling this function
+    ///   are never return (will go into an infinite loop).
+    ///
+    /// Note: It is recommended (but not required) that the new table's `capacity`
+    /// be greater than or equal to `self.items`. In case if `capacity <= self.items`
+    /// this function can never return. See [`RawTableInner::find_insert_slot`] for
+    /// more information.
+    ///
+    /// [`RawTableInner::find_insert_slot`]: RawTableInner::find_insert_slot
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[allow(clippy::inline_always)]
+    #[inline(always)]
+    unsafe fn resize_inner<A>(
+        &mut self,
+        alloc: &A,
+        capacity: usize,
+        hasher: &dyn Fn(&mut Self, usize) -> u64,
+        fallibility: Fallibility,
+        layout: TableLayout,
+    ) -> Result<(), TryReserveError>
+    where
+        A: Allocator,
+    {
+        // SAFETY: We know for sure that `alloc` and `layout` matches the [`Allocator`] and [`TableLayout`]
+        // that were used to allocate this table.
+        let mut new_table = self.prepare_resize(alloc, layout, capacity, fallibility)?;
+
+        // SAFETY: We know for sure that RawTableInner will outlive the
+        // returned `FullBucketsIndices` iterator, and the caller of this
+        // function ensures that the control bytes are properly initialized.
+        for full_byte_index in self.full_buckets_indices() {
+            // This may panic.
+            let hash = hasher(self, full_byte_index);
+
+            // SAFETY:
+            // We can use a simpler version of insert() here since:
+            // 1. There are no DELETED entries.
+            // 2. We know there is enough space in the table.
+            // 3. All elements are unique.
+            // 4. The caller of this function guarantees that `capacity > 0`
+            //    so `new_table` must already have some allocated memory.
+            // 5. We set `growth_left` and `items` fields of the new table
+            //    after the loop.
+            // 6. We insert into the table, at the returned index, the data
+            //    matching the given hash immediately after calling this function.
+            let (new_index, _) = new_table.prepare_insert_slot(hash);
+
+            // SAFETY:
+            //
+            // * `src` is valid for reads of `layout.size` bytes, since the
+            //   table is alive and the `full_byte_index` is guaranteed to be
+            //   within bounds (see `FullBucketsIndices::next_impl`);
+            //
+            // * `dst` is valid for writes of `layout.size` bytes, since the
+            //   caller ensures that `table_layout` matches the [`TableLayout`]
+            //   that was used to allocate old table and we have the `new_index`
+            //   returned by `prepare_insert_slot`.
+            //
+            // * Both `src` and `dst` are properly aligned.
+            //
+            // * Both `src` and `dst` point to different region of memory.
+            ptr::copy_nonoverlapping(
+                self.bucket_ptr(full_byte_index, layout.size),
+                new_table.bucket_ptr(new_index, layout.size),
+                layout.size,
+            );
+        }
+
+        // The hash function didn't panic, so we can safely set the
+        // `growth_left` and `items` fields of the new table.
+        new_table.growth_left -= self.items;
+        new_table.items = self.items;
+
+        // We successfully copied all elements without panicking. Now replace
+        // self with the new table. The old table will have its memory freed but
+        // the items will not be dropped (since they have been moved into the
+        // new table).
+        // SAFETY: The caller ensures that `table_layout` matches the [`TableLayout`]
+        // that was used to allocate this table.
+        mem::swap(self, &mut new_table);
+
+        Ok(())
+    }
+
+    /// Rehashes the contents of the table in place (i.e. without changing the
+    /// allocation).
+    ///
+    /// If `hasher` panics then some the table's contents may be lost.
+    ///
+    /// This uses dynamic dispatch to reduce the amount of
+    /// code generated, but it is eliminated by LLVM optimizations when inlined.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is [`undefined behavior`]:
+    ///
+    /// * The `size_of` must be equal to the size of the elements stored in the table;
+    ///
+    /// * The `drop` function (`fn(*mut u8)`) must be the actual drop function of
+    ///   the elements stored in the table.
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The [`RawTableInner`] must have properly initialized control bytes.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[allow(clippy::inline_always)]
+    #[cfg_attr(feature = "inline-more", inline(always))]
+    #[cfg_attr(not(feature = "inline-more"), inline)]
+    unsafe fn rehash_in_place(
+        &mut self,
+        hasher: &dyn Fn(&mut Self, usize) -> u64,
+        size_of: usize,
+        drop: Option<fn(*mut u8)>,
+    ) {
+        // If the hash function panics then properly clean up any elements
+        // that we haven't rehashed yet. We unfortunately can't preserve the
+        // element since we lost their hash and have no way of recovering it
+        // without risking another panic.
+        self.prepare_rehash_in_place();
+
+        let mut guard = guard(self, move |self_| {
+            if let Some(drop) = drop {
+                for i in 0..self_.buckets() {
+                    if *self_.ctrl(i) == DELETED {
+                        self_.set_ctrl(i, EMPTY);
+                        drop(self_.bucket_ptr(i, size_of));
+                        self_.items -= 1;
+                    }
+                }
+            }
+            self_.growth_left = bucket_mask_to_capacity(self_.bucket_mask) - self_.items;
+        });
+
+        // At this point, DELETED elements are elements that we haven't
+        // rehashed yet. Find them and re-insert them at their ideal
+        // position.
+        'outer: for i in 0..guard.buckets() {
+            if *guard.ctrl(i) != DELETED {
+                continue;
+            }
+
+            let i_p = guard.bucket_ptr(i, size_of);
+
+            'inner: loop {
+                // Hash the current item
+                let hash = hasher(*guard, i);
+
+                // Search for a suitable place to put it
+                //
+                // SAFETY: Caller of this function ensures that the control bytes
+                // are properly initialized.
+                let new_i = guard.find_insert_slot(hash).index;
+
+                // Probing works by scanning through all of the control
+                // bytes in groups, which may not be aligned to the group
+                // size. If both the new and old position fall within the
+                // same unaligned group, then there is no benefit in moving
+                // it and we can just continue to the next item.
+                if likely(guard.is_in_same_group(i, new_i, hash)) {
+                    guard.set_ctrl_h2(i, hash);
+                    continue 'outer;
+                }
+
+                let new_i_p = guard.bucket_ptr(new_i, size_of);
+
+                // We are moving the current item to a new position. Write
+                // our H2 to the control byte of the new position.
+                let prev_ctrl = guard.replace_ctrl_h2(new_i, hash);
+                if prev_ctrl == EMPTY {
+                    guard.set_ctrl(i, EMPTY);
+                    // If the target slot is empty, simply move the current
+                    // element into the new slot and clear the old control
+                    // byte.
+                    ptr::copy_nonoverlapping(i_p, new_i_p, size_of);
+                    continue 'outer;
+                } else {
+                    // If the target slot is occupied, swap the two elements
+                    // and then continue processing the element that we just
+                    // swapped into the old slot.
+                    debug_assert_eq!(prev_ctrl, DELETED);
+                    ptr::swap_nonoverlapping(i_p, new_i_p, size_of);
+                    continue 'inner;
+                }
+            }
+        }
+
+        guard.growth_left = bucket_mask_to_capacity(guard.bucket_mask) - guard.items;
+
+        mem::forget(guard);
+    }
+
+    /// Deallocates the table without dropping any entries.
+    ///
+    /// # Note
+    ///
+    /// This function must be called only after [`drop_elements`](RawTable::drop_elements),
+    /// else it can lead to leaking of memory. Also calling this function automatically
+    /// makes invalid (dangling) all instances of buckets ([`Bucket`]) and makes invalid
+    /// (dangling) the `ctrl` field of the table.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is [`Undefined Behavior`]:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * The `alloc` must be the same [`Allocator`] as the `Allocator` that was used
+    ///   to allocate this table.
+    ///
+    /// * The `table_layout` must be the same [`TableLayout`] as the `TableLayout` that was used
+    ///   to allocate this table.
+    ///
+    /// See also [`GlobalAlloc::dealloc`] or [`Allocator::deallocate`] for more  information.
+    ///
+    /// [`Undefined Behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    /// [`GlobalAlloc::dealloc`]: https://doc.rust-lang.org/alloc/alloc/trait.GlobalAlloc.html#tymethod.dealloc
+    /// [`Allocator::deallocate`]: https://doc.rust-lang.org/alloc/alloc/trait.Allocator.html#tymethod.deallocate
+    #[inline]
+    unsafe fn free_buckets<A>(&mut self, alloc: &A, table_layout: TableLayout)
+    where
+        A: Allocator,
+    {
+        // SAFETY: The caller must uphold the safety contract for `free_buckets`
+        // method.
+        let (ptr, layout) = self.allocation_info(table_layout);
+        alloc.deallocate(ptr, layout);
+    }
+
+    /// Returns a pointer to the allocated memory and the layout that was used to
+    /// allocate the table.
+    ///
+    /// # Safety
+    ///
+    /// Caller of this function must observe the following safety rules:
+    ///
+    /// * The [`RawTableInner`] has already been allocated, otherwise
+    ///   calling this function results in [`undefined behavior`]
+    ///
+    /// * The `table_layout` must be the same [`TableLayout`] as the `TableLayout`
+    ///   that was used to allocate this table. Failure to comply with this condition
+    ///   may result in [`undefined behavior`].
+    ///
+    /// See also [`GlobalAlloc::dealloc`] or [`Allocator::deallocate`] for more  information.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    /// [`GlobalAlloc::dealloc`]: https://doc.rust-lang.org/alloc/alloc/trait.GlobalAlloc.html#tymethod.dealloc
+    /// [`Allocator::deallocate`]: https://doc.rust-lang.org/alloc/alloc/trait.Allocator.html#tymethod.deallocate
+    #[inline]
+    unsafe fn allocation_info(&self, table_layout: TableLayout) -> (NonNull<u8>, Layout) {
+        debug_assert!(
+            !self.is_empty_singleton(),
+            "this function can only be called on non-empty tables"
+        );
+
+        // Avoid `Option::unwrap_or_else` because it bloats LLVM IR.
+        let (layout, ctrl_offset) = match table_layout.calculate_layout_for(self.buckets()) {
+            Some(lco) => lco,
+            None => unsafe { hint::unreachable_unchecked() },
+        };
+        (
+            // SAFETY: The caller must uphold the safety contract for `allocation_info` method.
+            unsafe { NonNull::new_unchecked(self.ctrl.as_ptr().sub(ctrl_offset)) },
+            layout,
+        )
+    }
+
+    /// Returns a pointer to the allocated memory and the layout that was used to
+    /// allocate the table. If [`RawTableInner`] has not been allocated, this
+    /// function return `dangling` pointer and `()` (unit) layout.
+    ///
+    /// # Safety
+    ///
+    /// The `table_layout` must be the same [`TableLayout`] as the `TableLayout`
+    /// that was used to allocate this table. Failure to comply with this condition
+    /// may result in [`undefined behavior`].
+    ///
+    /// See also [`GlobalAlloc::dealloc`] or [`Allocator::deallocate`] for more  information.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    /// [`GlobalAlloc::dealloc`]: https://doc.rust-lang.org/alloc/alloc/trait.GlobalAlloc.html#tymethod.dealloc
+    /// [`Allocator::deallocate`]: https://doc.rust-lang.org/alloc/alloc/trait.Allocator.html#tymethod.deallocate
+    #[cfg(feature = "raw")]
+    unsafe fn allocation_info_or_zero(&self, table_layout: TableLayout) -> (NonNull<u8>, Layout) {
+        if self.is_empty_singleton() {
+            (NonNull::dangling(), Layout::new::<()>())
+        } else {
+            // SAFETY:
+            // 1. We have checked that our table is allocated.
+            // 2. The caller ensures that `table_layout` matches the [`TableLayout`]
+            // that was used to allocate this table.
+            unsafe { self.allocation_info(table_layout) }
+        }
+    }
+
+    /// Marks all table buckets as empty without dropping their contents.
+    #[inline]
+    fn clear_no_drop(&mut self) {
+        if !self.is_empty_singleton() {
+            unsafe {
+                self.ctrl(0).write_bytes(EMPTY, self.num_ctrl_bytes());
+            }
+        }
+        self.items = 0;
+        self.growth_left = bucket_mask_to_capacity(self.bucket_mask);
+    }
+
+    /// Erases the [`Bucket`]'s control byte at the given index so that it does not
+    /// triggered as full, decreases the `items` of the table and, if it can be done,
+    /// increases `self.growth_left`.
+    ///
+    /// This function does not actually erase / drop the [`Bucket`] itself, i.e. it
+    /// does not make any changes to the `data` parts of the table. The caller of this
+    /// function must take care to properly drop the `data`, otherwise calling this
+    /// function may result in a memory leak.
+    ///
+    /// # Safety
+    ///
+    /// You must observe the following safety rules when calling this function:
+    ///
+    /// * The [`RawTableInner`] has already been allocated;
+    ///
+    /// * It must be the full control byte at the given position;
+    ///
+    /// * The `index` must not be greater than the `RawTableInner.bucket_mask`, i.e.
+    ///   `index <= RawTableInner.bucket_mask` or, in other words, `(index + 1)` must
+    ///   be no greater than the number returned by the function [`RawTableInner::buckets`].
+    ///
+    /// Calling this function on a table that has not been allocated results in [`undefined behavior`].
+    ///
+    /// Calling this function on a table with no elements is unspecified, but calling subsequent
+    /// functions is likely to result in [`undefined behavior`] due to overflow subtraction
+    /// (`self.items -= 1 cause overflow when self.items == 0`).
+    ///
+    /// See also [`Bucket::as_ptr`] method, for more information about of properly removing
+    /// or saving `data element` from / into the [`RawTable`] / [`RawTableInner`].
+    ///
+    /// [`RawTableInner::buckets`]: RawTableInner::buckets
+    /// [`Bucket::as_ptr`]: Bucket::as_ptr
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline]
+    unsafe fn erase(&mut self, index: usize) {
+        debug_assert!(self.is_bucket_full(index));
+
+        // This is the same as `index.wrapping_sub(Group::WIDTH) % self.buckets()` because
+        // the number of buckets is a power of two, and `self.bucket_mask = self.buckets() - 1`.
+        let index_before = index.wrapping_sub(Group::WIDTH) & self.bucket_mask;
+        // SAFETY:
+        // - The caller must uphold the safety contract for `erase` method;
+        // - `index_before` is guaranteed to be in range due to masking with `self.bucket_mask`
+        let empty_before = Group::load(self.ctrl(index_before)).match_empty();
+        let empty_after = Group::load(self.ctrl(index)).match_empty();
+
+        // Inserting and searching in the map is performed by two key functions:
+        //
+        // - The `find_insert_slot` function that looks up the index of any `EMPTY` or `DELETED`
+        //   slot in a group to be able to insert. If it doesn't find an `EMPTY` or `DELETED`
+        //   slot immediately in the first group, it jumps to the next `Group` looking for it,
+        //   and so on until it has gone through all the groups in the control bytes.
+        //
+        // - The `find_inner` function that looks for the index of the desired element by looking
+        //   at all the `FULL` bytes in the group. If it did not find the element right away, and
+        //   there is no `EMPTY` byte in the group, then this means that the `find_insert_slot`
+        //   function may have found a suitable slot in the next group. Therefore, `find_inner`
+        //   jumps further, and if it does not find the desired element and again there is no `EMPTY`
+        //   byte, then it jumps further, and so on. The search stops only if `find_inner` function
+        //   finds the desired element or hits an `EMPTY` slot/byte.
+        //
+        // Accordingly, this leads to two consequences:
+        //
+        // - The map must have `EMPTY` slots (bytes);
+        //
+        // - You can't just mark the byte to be erased as `EMPTY`, because otherwise the `find_inner`
+        //   function may stumble upon an `EMPTY` byte before finding the desired element and stop
+        //   searching.
+        //
+        // Thus it is necessary to check all bytes after and before the erased element. If we are in
+        // a contiguous `Group` of `FULL` or `DELETED` bytes (the number of `FULL` or `DELETED` bytes
+        // before and after is greater than or equal to `Group::WIDTH`), then we must mark our byte as
+        // `DELETED` in order for the `find_inner` function to go further. On the other hand, if there
+        // is at least one `EMPTY` slot in the `Group`, then the `find_inner` function will still stumble
+        // upon an `EMPTY` byte, so we can safely mark our erased byte as `EMPTY` as well.
+        //
+        // Finally, since `index_before == (index.wrapping_sub(Group::WIDTH) & self.bucket_mask) == index`
+        // and given all of the above, tables smaller than the group width (self.buckets() < Group::WIDTH)
+        // cannot have `DELETED` bytes.
+        //
+        // Note that in this context `leading_zeros` refers to the bytes at the end of a group, while
+        // `trailing_zeros` refers to the bytes at the beginning of a group.
+        let ctrl = if empty_before.leading_zeros() + empty_after.trailing_zeros() >= Group::WIDTH {
+            DELETED
+        } else {
+            self.growth_left += 1;
+            EMPTY
+        };
+        // SAFETY: the caller must uphold the safety contract for `erase` method.
+        self.set_ctrl(index, ctrl);
+        self.items -= 1;
+    }
+}
+
+impl<T: Clone, A: Allocator + Clone> Clone for RawTable<T, A> {
+    fn clone(&self) -> Self {
+        if self.table.is_empty_singleton() {
+            Self::new_in(self.alloc.clone())
+        } else {
+            unsafe {
+                // Avoid `Result::ok_or_else` because it bloats LLVM IR.
+                //
+                // SAFETY: This is safe as we are taking the size of an already allocated table
+                // and therefore сapacity overflow cannot occur, `self.table.buckets()` is power
+                // of two and all allocator errors will be caught inside `RawTableInner::new_uninitialized`.
+                let mut new_table = match Self::new_uninitialized(
+                    self.alloc.clone(),
+                    self.table.buckets(),
+                    Fallibility::Infallible,
+                ) {
+                    Ok(table) => table,
+                    Err(_) => hint::unreachable_unchecked(),
+                };
+
+                // Cloning elements may fail (the clone function may panic). But we don't
+                // need to worry about uninitialized control bits, since:
+                // 1. The number of items (elements) in the table is zero, which means that
+                //    the control bits will not be readed by Drop function.
+                // 2. The `clone_from_spec` method will first copy all control bits from
+                //    `self` (thus initializing them). But this will not affect the `Drop`
+                //    function, since the `clone_from_spec` function sets `items` only after
+                //    successfully clonning all elements.
+                new_table.clone_from_spec(self);
+                new_table
+            }
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        if source.table.is_empty_singleton() {
+            let mut old_inner = mem::replace(&mut self.table, RawTableInner::NEW);
+            unsafe {
+                // SAFETY:
+                // 1. We call the function only once;
+                // 2. We know for sure that `alloc` and `table_layout` matches the [`Allocator`]
+                //    and [`TableLayout`] that were used to allocate this table.
+                // 3. If any elements' drop function panics, then there will only be a memory leak,
+                //    because we have replaced the inner table with a new one.
+                old_inner.drop_inner_table::<T, _>(&self.alloc, Self::TABLE_LAYOUT);
+            }
+        } else {
+            unsafe {
+                // Make sure that if any panics occurs, we clear the table and
+                // leave it in an empty state.
+                let mut self_ = guard(self, |self_| {
+                    self_.clear_no_drop();
+                });
+
+                // First, drop all our elements without clearing the control
+                // bytes. If this panics then the scope guard will clear the
+                // table, leaking any elements that were not dropped yet.
+                //
+                // This leak is unavoidable: we can't try dropping more elements
+                // since this could lead to another panic and abort the process.
+                //
+                // SAFETY: If something gets wrong we clear our table right after
+                // dropping the elements, so there is no double drop, since `items`
+                // will be equal to zero.
+                self_.table.drop_elements::<T>();
+
+                // If necessary, resize our table to match the source.
+                if self_.buckets() != source.buckets() {
+                    let new_inner = match RawTableInner::new_uninitialized(
+                        &self_.alloc,
+                        Self::TABLE_LAYOUT,
+                        source.buckets(),
+                        Fallibility::Infallible,
+                    ) {
+                        Ok(table) => table,
+                        Err(_) => hint::unreachable_unchecked(),
+                    };
+                    // Replace the old inner with new uninitialized one. It's ok, since if something gets
+                    // wrong `ScopeGuard` will initialize all control bytes and leave empty table.
+                    let mut old_inner = mem::replace(&mut self_.table, new_inner);
+                    if !old_inner.is_empty_singleton() {
+                        // SAFETY:
+                        // 1. We have checked that our table is allocated.
+                        // 2. We know for sure that `alloc` and `table_layout` matches
+                        // the [`Allocator`] and [`TableLayout`] that were used to allocate this table.
+                        old_inner.free_buckets(&self_.alloc, Self::TABLE_LAYOUT);
+                    }
+                }
+
+                // Cloning elements may fail (the clone function may panic), but the `ScopeGuard`
+                // inside the `clone_from_impl` function will take care of that, dropping all
+                // cloned elements if necessary. Our `ScopeGuard` will clear the table.
+                self_.clone_from_spec(source);
+
+                // Disarm the scope guard if cloning was successful.
+                ScopeGuard::into_inner(self_);
+            }
+        }
+    }
+}
+
+/// Specialization of `clone_from` for `Copy` types
+trait RawTableClone {
+    unsafe fn clone_from_spec(&mut self, source: &Self);
+}
+impl<T: Clone, A: Allocator + Clone> RawTableClone for RawTable<T, A> {
+    default_fn! {
+        #[cfg_attr(feature = "inline-more", inline)]
+        unsafe fn clone_from_spec(&mut self, source: &Self) {
+            self.clone_from_impl(source);
+        }
+    }
+}
+#[cfg(feature = "nightly")]
+impl<T: Copy, A: Allocator + Clone> RawTableClone for RawTable<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn clone_from_spec(&mut self, source: &Self) {
+        source
+            .table
+            .ctrl(0)
+            .copy_to_nonoverlapping(self.table.ctrl(0), self.table.num_ctrl_bytes());
+        source
+            .data_start()
+            .as_ptr()
+            .copy_to_nonoverlapping(self.data_start().as_ptr(), self.table.buckets());
+
+        self.table.items = source.table.items;
+        self.table.growth_left = source.table.growth_left;
+    }
+}
+
+impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
+    /// Common code for clone and clone_from. Assumes:
+    /// - `self.buckets() == source.buckets()`.
+    /// - Any existing elements have been dropped.
+    /// - The control bytes are not initialized yet.
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn clone_from_impl(&mut self, source: &Self) {
+        // Copy the control bytes unchanged. We do this in a single pass
+        source
+            .table
+            .ctrl(0)
+            .copy_to_nonoverlapping(self.table.ctrl(0), self.table.num_ctrl_bytes());
+
+        // The cloning of elements may panic, in which case we need
+        // to make sure we drop only the elements that have been
+        // cloned so far.
+        let mut guard = guard((0, &mut *self), |(index, self_)| {
+            if T::NEEDS_DROP {
+                for i in 0..=*index {
+                    if self_.is_bucket_full(i) {
+                        self_.bucket(i).drop();
+                    }
+                }
+            }
+        });
+
+        for from in source.iter() {
+            let index = source.bucket_index(&from);
+            let to = guard.1.bucket(index);
+            to.write(from.as_ref().clone());
+
+            // Update the index in case we need to unwind.
+            guard.0 = index;
+        }
+
+        // Successfully cloned all items, no need to clean up.
+        mem::forget(guard);
+
+        self.table.items = source.table.items;
+        self.table.growth_left = source.table.growth_left;
+    }
+
+    /// Variant of `clone_from` to use when a hasher is available.
+    #[cfg(feature = "raw")]
+    pub fn clone_from_with_hasher(&mut self, source: &Self, hasher: impl Fn(&T) -> u64) {
+        // If we have enough capacity in the table, just clear it and insert
+        // elements one by one. We don't do this if we have the same number of
+        // buckets as the source since we can just copy the contents directly
+        // in that case.
+        if self.table.buckets() != source.table.buckets()
+            && bucket_mask_to_capacity(self.table.bucket_mask) >= source.len()
+        {
+            self.clear();
+
+            let mut guard_self = guard(&mut *self, |self_| {
+                // Clear the partially copied table if a panic occurs, otherwise
+                // items and growth_left will be out of sync with the contents
+                // of the table.
+                self_.clear();
+            });
+
+            unsafe {
+                for item in source.iter() {
+                    // This may panic.
+                    let item = item.as_ref().clone();
+                    let hash = hasher(&item);
+
+                    // We can use a simpler version of insert() here since:
+                    // - there are no DELETED entries.
+                    // - we know there is enough space in the table.
+                    // - all elements are unique.
+                    let (index, _) = guard_self.table.prepare_insert_slot(hash);
+                    guard_self.bucket(index).write(item);
+                }
+            }
+
+            // Successfully cloned all items, no need to clean up.
+            mem::forget(guard_self);
+
+            self.table.items = source.table.items;
+            self.table.growth_left -= source.table.items;
+        } else {
+            self.clone_from(source);
+        }
+    }
+}
+
+impl<T, A: Allocator + Default> Default for RawTable<T, A> {
+    #[inline]
+    fn default() -> Self {
+        Self::new_in(Default::default())
+    }
+}
+
+#[cfg(feature = "nightly")]
+unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawTable<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        unsafe {
+            // SAFETY:
+            // 1. We call the function only once;
+            // 2. We know for sure that `alloc` and `table_layout` matches the [`Allocator`]
+            //    and [`TableLayout`] that were used to allocate this table.
+            // 3. If the drop function of any elements fails, then only a memory leak will occur,
+            //    and we don't care because we are inside the `Drop` function of the `RawTable`,
+            //    so there won't be any table left in an inconsistent state.
+            self.table
+                .drop_inner_table::<T, _>(&self.alloc, Self::TABLE_LAYOUT);
+        }
+    }
+}
+#[cfg(not(feature = "nightly"))]
+impl<T, A: Allocator> Drop for RawTable<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        unsafe {
+            // SAFETY:
+            // 1. We call the function only once;
+            // 2. We know for sure that `alloc` and `table_layout` matches the [`Allocator`]
+            //    and [`TableLayout`] that were used to allocate this table.
+            // 3. If the drop function of any elements fails, then only a memory leak will occur,
+            //    and we don't care because we are inside the `Drop` function of the `RawTable`,
+            //    so there won't be any table left in an inconsistent state.
+            self.table
+                .drop_inner_table::<T, _>(&self.alloc, Self::TABLE_LAYOUT);
+        }
+    }
+}
+
+impl<T, A: Allocator> IntoIterator for RawTable<T, A> {
+    type Item = T;
+    type IntoIter = RawIntoIter<T, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> RawIntoIter<T, A> {
+        unsafe {
+            let iter = self.iter();
+            self.into_iter_from(iter)
+        }
+    }
+}
+
+/// Iterator over a sub-range of a table. Unlike `RawIter` this iterator does
+/// not track an item count.
+pub(crate) struct RawIterRange<T> {
+    // Mask of full buckets in the current group. Bits are cleared from this
+    // mask as each element is processed.
+    current_group: BitMaskIter,
+
+    // Pointer to the buckets for the current group.
+    data: Bucket<T>,
+
+    // Pointer to the next group of control bytes,
+    // Must be aligned to the group size.
+    next_ctrl: *const u8,
+
+    // Pointer one past the last control byte of this range.
+    end: *const u8,
+}
+
+impl<T> RawIterRange<T> {
+    /// Returns a `RawIterRange` covering a subset of a table.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is
+    /// [`undefined behavior`]:
+    ///
+    /// * `ctrl` must be [valid] for reads, i.e. table outlives the `RawIterRange`;
+    ///
+    /// * `ctrl` must be properly aligned to the group size (Group::WIDTH);
+    ///
+    /// * `ctrl` must point to the array of properly initialized control bytes;
+    ///
+    /// * `data` must be the [`Bucket`] at the `ctrl` index in the table;
+    ///
+    /// * the value of `len` must be less than or equal to the number of table buckets,
+    ///   and the returned value of `ctrl.as_ptr().add(len).offset_from(ctrl.as_ptr())`
+    ///   must be positive.
+    ///
+    /// * The `ctrl.add(len)` pointer must be either in bounds or one
+    ///   byte past the end of the same [allocated table].
+    ///
+    /// * The `len` must be a power of two.
+    ///
+    /// [`undefined behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn new(ctrl: *const u8, data: Bucket<T>, len: usize) -> Self {
+        debug_assert_ne!(len, 0);
+        debug_assert_eq!(ctrl as usize % Group::WIDTH, 0);
+        // SAFETY: The caller must uphold the safety rules for the [`RawIterRange::new`]
+        let end = ctrl.add(len);
+
+        // Load the first group and advance ctrl to point to the next group
+        // SAFETY: The caller must uphold the safety rules for the [`RawIterRange::new`]
+        let current_group = Group::load_aligned(ctrl).match_full();
+        let next_ctrl = ctrl.add(Group::WIDTH);
+
+        Self {
+            current_group: current_group.into_iter(),
+            data,
+            next_ctrl,
+            end,
+        }
+    }
+
+    /// Splits a `RawIterRange` into two halves.
+    ///
+    /// Returns `None` if the remaining range is smaller than or equal to the
+    /// group width.
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[cfg(feature = "rayon")]
+    pub(crate) fn split(mut self) -> (Self, Option<RawIterRange<T>>) {
+        unsafe {
+            if self.end <= self.next_ctrl {
+                // Nothing to split if the group that we are current processing
+                // is the last one.
+                (self, None)
+            } else {
+                // len is the remaining number of elements after the group that
+                // we are currently processing. It must be a multiple of the
+                // group size (small tables are caught by the check above).
+                let len = offset_from(self.end, self.next_ctrl);
+                debug_assert_eq!(len % Group::WIDTH, 0);
+
+                // Split the remaining elements into two halves, but round the
+                // midpoint down in case there is an odd number of groups
+                // remaining. This ensures that:
+                // - The tail is at least 1 group long.
+                // - The split is roughly even considering we still have the
+                //   current group to process.
+                let mid = (len / 2) & !(Group::WIDTH - 1);
+
+                let tail = Self::new(
+                    self.next_ctrl.add(mid),
+                    self.data.next_n(Group::WIDTH).next_n(mid),
+                    len - mid,
+                );
+                debug_assert_eq!(
+                    self.data.next_n(Group::WIDTH).next_n(mid).ptr,
+                    tail.data.ptr
+                );
+                debug_assert_eq!(self.end, tail.end);
+                self.end = self.next_ctrl.add(mid);
+                debug_assert_eq!(self.end.add(Group::WIDTH), tail.next_ctrl);
+                (self, Some(tail))
+            }
+        }
+    }
+
+    /// # Safety
+    /// If DO_CHECK_PTR_RANGE is false, caller must ensure that we never try to iterate
+    /// after yielding all elements.
+    #[cfg_attr(feature = "inline-more", inline)]
+    unsafe fn next_impl<const DO_CHECK_PTR_RANGE: bool>(&mut self) -> Option<Bucket<T>> {
+        loop {
+            if let Some(index) = self.current_group.next() {
+                return Some(self.data.next_n(index));
+            }
+
+            if DO_CHECK_PTR_RANGE && self.next_ctrl >= self.end {
+                return None;
+            }
+
+            // We might read past self.end up to the next group boundary,
+            // but this is fine because it only occurs on tables smaller
+            // than the group size where the trailing control bytes are all
+            // EMPTY. On larger tables self.end is guaranteed to be aligned
+            // to the group size (since tables are power-of-two sized).
+            self.current_group = Group::load_aligned(self.next_ctrl).match_full().into_iter();
+            self.data = self.data.next_n(Group::WIDTH);
+            self.next_ctrl = self.next_ctrl.add(Group::WIDTH);
+        }
+    }
+}
+
+// We make raw iterators unconditionally Send and Sync, and let the PhantomData
+// in the actual iterator implementations determine the real Send/Sync bounds.
+unsafe impl<T> Send for RawIterRange<T> {}
+unsafe impl<T> Sync for RawIterRange<T> {}
+
+impl<T> Clone for RawIterRange<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            data: self.data.clone(),
+            next_ctrl: self.next_ctrl,
+            current_group: self.current_group,
+            end: self.end,
+        }
+    }
+}
+
+impl<T> Iterator for RawIterRange<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<Bucket<T>> {
+        unsafe {
+            // SAFETY: We set checker flag to true.
+            self.next_impl::<true>()
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        // We don't have an item count, so just guess based on the range size.
+        let remaining_buckets = if self.end > self.next_ctrl {
+            unsafe { offset_from(self.end, self.next_ctrl) }
+        } else {
+            0
+        };
+
+        // Add a group width to include the group we are currently processing.
+        (0, Some(Group::WIDTH + remaining_buckets))
+    }
+}
+
+impl<T> FusedIterator for RawIterRange<T> {}
+
+/// Iterator which returns a raw pointer to every full bucket in the table.
+///
+/// For maximum flexibility this iterator is not bound by a lifetime, but you
+/// must observe several rules when using it:
+/// - You must not free the hash table while iterating (including via growing/shrinking).
+/// - It is fine to erase a bucket that has been yielded by the iterator.
+/// - Erasing a bucket that has not yet been yielded by the iterator may still
+///   result in the iterator yielding that bucket (unless `reflect_remove` is called).
+/// - It is unspecified whether an element inserted after the iterator was
+///   created will be yielded by that iterator (unless `reflect_insert` is called).
+/// - The order in which the iterator yields bucket is unspecified and may
+///   change in the future.
+pub struct RawIter<T> {
+    pub(crate) iter: RawIterRange<T>,
+    items: usize,
+}
+
+impl<T> RawIter<T> {
+    /// Refresh the iterator so that it reflects a removal from the given bucket.
+    ///
+    /// For the iterator to remain valid, this method must be called once
+    /// for each removed bucket before `next` is called again.
+    ///
+    /// This method should be called _before_ the removal is made. It is not necessary to call this
+    /// method if you are removing an item that this iterator yielded in the past.
+    #[cfg(feature = "raw")]
+    pub unsafe fn reflect_remove(&mut self, b: &Bucket<T>) {
+        self.reflect_toggle_full(b, false);
+    }
+
+    /// Refresh the iterator so that it reflects an insertion into the given bucket.
+    ///
+    /// For the iterator to remain valid, this method must be called once
+    /// for each insert before `next` is called again.
+    ///
+    /// This method does not guarantee that an insertion of a bucket with a greater
+    /// index than the last one yielded will be reflected in the iterator.
+    ///
+    /// This method should be called _after_ the given insert is made.
+    #[cfg(feature = "raw")]
+    pub unsafe fn reflect_insert(&mut self, b: &Bucket<T>) {
+        self.reflect_toggle_full(b, true);
+    }
+
+    /// Refresh the iterator so that it reflects a change to the state of the given bucket.
+    #[cfg(feature = "raw")]
+    unsafe fn reflect_toggle_full(&mut self, b: &Bucket<T>, is_insert: bool) {
+        if b.as_ptr() > self.iter.data.as_ptr() {
+            // The iterator has already passed the bucket's group.
+            // So the toggle isn't relevant to this iterator.
+            return;
+        }
+
+        if self.iter.next_ctrl < self.iter.end
+            && b.as_ptr() <= self.iter.data.next_n(Group::WIDTH).as_ptr()
+        {
+            // The iterator has not yet reached the bucket's group.
+            // We don't need to reload anything, but we do need to adjust the item count.
+
+            if cfg!(debug_assertions) {
+                // Double-check that the user isn't lying to us by checking the bucket state.
+                // To do that, we need to find its control byte. We know that self.iter.data is
+                // at self.iter.next_ctrl - Group::WIDTH, so we work from there:
+                let offset = offset_from(self.iter.data.as_ptr(), b.as_ptr());
+                let ctrl = self.iter.next_ctrl.sub(Group::WIDTH).add(offset);
+                // This method should be called _before_ a removal, or _after_ an insert,
+                // so in both cases the ctrl byte should indicate that the bucket is full.
+                assert!(is_full(*ctrl));
+            }
+
+            if is_insert {
+                self.items += 1;
+            } else {
+                self.items -= 1;
+            }
+
+            return;
+        }
+
+        // The iterator is at the bucket group that the toggled bucket is in.
+        // We need to do two things:
+        //
+        //  - Determine if the iterator already yielded the toggled bucket.
+        //    If it did, we're done.
+        //  - Otherwise, update the iterator cached group so that it won't
+        //    yield a to-be-removed bucket, or _will_ yield a to-be-added bucket.
+        //    We'll also need to update the item count accordingly.
+        if let Some(index) = self.iter.current_group.0.lowest_set_bit() {
+            let next_bucket = self.iter.data.next_n(index);
+            if b.as_ptr() > next_bucket.as_ptr() {
+                // The toggled bucket is "before" the bucket the iterator would yield next. We
+                // therefore don't need to do anything --- the iterator has already passed the
+                // bucket in question.
+                //
+                // The item count must already be correct, since a removal or insert "prior" to
+                // the iterator's position wouldn't affect the item count.
+            } else {
+                // The removed bucket is an upcoming bucket. We need to make sure it does _not_
+                // get yielded, and also that it's no longer included in the item count.
+                //
+                // NOTE: We can't just reload the group here, both since that might reflect
+                // inserts we've already passed, and because that might inadvertently unset the
+                // bits for _other_ removals. If we do that, we'd have to also decrement the
+                // item count for those other bits that we unset. But the presumably subsequent
+                // call to reflect for those buckets might _also_ decrement the item count.
+                // Instead, we _just_ flip the bit for the particular bucket the caller asked
+                // us to reflect.
+                let our_bit = offset_from(self.iter.data.as_ptr(), b.as_ptr());
+                let was_full = self.iter.current_group.flip(our_bit);
+                debug_assert_ne!(was_full, is_insert);
+
+                if is_insert {
+                    self.items += 1;
+                } else {
+                    self.items -= 1;
+                }
+
+                if cfg!(debug_assertions) {
+                    if b.as_ptr() == next_bucket.as_ptr() {
+                        // The removed bucket should no longer be next
+                        debug_assert_ne!(self.iter.current_group.0.lowest_set_bit(), Some(index));
+                    } else {
+                        // We should not have changed what bucket comes next.
+                        debug_assert_eq!(self.iter.current_group.0.lowest_set_bit(), Some(index));
+                    }
+                }
+            }
+        } else {
+            // We must have already iterated past the removed item.
+        }
+    }
+
+    unsafe fn drop_elements(&mut self) {
+        if T::NEEDS_DROP && self.items != 0 {
+            for item in self {
+                item.drop();
+            }
+        }
+    }
+}
+
+impl<T> Clone for RawIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            iter: self.iter.clone(),
+            items: self.items,
+        }
+    }
+}
+
+impl<T> Iterator for RawIter<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<Bucket<T>> {
+        // Inner iterator iterates over buckets
+        // so it can do unnecessary work if we already yielded all items.
+        if self.items == 0 {
+            return None;
+        }
+
+        let nxt = unsafe {
+            // SAFETY: We check number of items to yield using `items` field.
+            self.iter.next_impl::<false>()
+        };
+
+        debug_assert!(nxt.is_some());
+        self.items -= 1;
+
+        nxt
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.items, Some(self.items))
+    }
+}
+
+impl<T> ExactSizeIterator for RawIter<T> {}
+impl<T> FusedIterator for RawIter<T> {}
+
+/// Iterator which returns an index of every full bucket in the table.
+///
+/// For maximum flexibility this iterator is not bound by a lifetime, but you
+/// must observe several rules when using it:
+/// - You must not free the hash table while iterating (including via growing/shrinking).
+/// - It is fine to erase a bucket that has been yielded by the iterator.
+/// - Erasing a bucket that has not yet been yielded by the iterator may still
+///   result in the iterator yielding index of that bucket.
+/// - It is unspecified whether an element inserted after the iterator was
+///   created will be yielded by that iterator.
+/// - The order in which the iterator yields indices of the buckets is unspecified
+///   and may change in the future.
+pub(crate) struct FullBucketsIndices {
+    // Mask of full buckets in the current group. Bits are cleared from this
+    // mask as each element is processed.
+    current_group: BitMaskIter,
+
+    // Initial value of the bytes' indices of the current group (relative
+    // to the start of the control bytes).
+    group_first_index: usize,
+
+    // Pointer to the current group of control bytes,
+    // Must be aligned to the group size (Group::WIDTH).
+    ctrl: NonNull<u8>,
+
+    // Number of elements in the table.
+    items: usize,
+}
+
+impl FullBucketsIndices {
+    /// Advances the iterator and returns the next value.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is
+    /// [`Undefined Behavior`]:
+    ///
+    /// * The [`RawTableInner`] / [`RawTable`] must be alive and not moved,
+    ///   i.e. table outlives the `FullBucketsIndices`;
+    ///
+    /// * It never tries to iterate after getting all elements.
+    ///
+    /// [`Undefined Behavior`]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[inline(always)]
+    unsafe fn next_impl(&mut self) -> Option<usize> {
+        loop {
+            if let Some(index) = self.current_group.next() {
+                // The returned `self.group_first_index + index` will always
+                // be in the range `0..self.buckets()`. See explanation below.
+                return Some(self.group_first_index + index);
+            }
+
+            // SAFETY: The caller of this function ensures that:
+            //
+            // 1. It never tries to iterate after getting all the elements;
+            // 2. The table is alive and did not moved;
+            // 3. The first `self.ctrl` pointed to the start of the array of control bytes.
+            //
+            // Taking the above into account, we always stay within the bounds, because:
+            //
+            // 1. For tables smaller than the group width (self.buckets() <= Group::WIDTH),
+            //    we will never end up in the given branch, since we should have already
+            //    yielded all the elements of the table.
+            //
+            // 2. For tables larger than the group width. The the number of buckets is a
+            //    power of two (2 ^ n), Group::WIDTH is also power of two (2 ^ k). Sinse
+            //    `(2 ^ n) > (2 ^ k)`, than `(2 ^ n) % (2 ^ k) = 0`. As we start from the
+            //    the start of the array of control bytes, and never try to iterate after
+            //    getting all the elements, the last `self.ctrl` will be equal to
+            //    the `self.buckets() - Group::WIDTH`, so `self.current_group.next()`
+            //    will always contains indices within the range `0..Group::WIDTH`,
+            //    and subsequent `self.group_first_index + index` will always return a
+            //    number less than `self.buckets()`.
+            self.ctrl = NonNull::new_unchecked(self.ctrl.as_ptr().add(Group::WIDTH));
+
+            // SAFETY: See explanation above.
+            self.current_group = Group::load_aligned(self.ctrl.as_ptr())
+                .match_full()
+                .into_iter();
+            self.group_first_index += Group::WIDTH;
+        }
+    }
+}
+
+impl Iterator for FullBucketsIndices {
+    type Item = usize;
+
+    /// Advances the iterator and returns the next value. It is up to
+    /// the caller to ensure that the `RawTable` outlives the `FullBucketsIndices`,
+    /// because we cannot make the `next` method unsafe.
+    #[inline(always)]
+    fn next(&mut self) -> Option<usize> {
+        // Return if we already yielded all items.
+        if self.items == 0 {
+            return None;
+        }
+
+        let nxt = unsafe {
+            // SAFETY:
+            // 1. We check number of items to yield using `items` field.
+            // 2. The caller ensures that the table is alive and has not moved.
+            self.next_impl()
+        };
+
+        debug_assert!(nxt.is_some());
+        self.items -= 1;
+
+        nxt
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.items, Some(self.items))
+    }
+}
+
+impl ExactSizeIterator for FullBucketsIndices {}
+impl FusedIterator for FullBucketsIndices {}
+
+/// Iterator which consumes a table and returns elements.
+pub struct RawIntoIter<T, A: Allocator = Global> {
+    iter: RawIter<T>,
+    allocation: Option<(NonNull<u8>, Layout, A)>,
+    marker: PhantomData<T>,
+}
+
+impl<T, A: Allocator> RawIntoIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn iter(&self) -> RawIter<T> {
+        self.iter.clone()
+    }
+}
+
+unsafe impl<T, A: Allocator> Send for RawIntoIter<T, A>
+where
+    T: Send,
+    A: Send,
+{
+}
+unsafe impl<T, A: Allocator> Sync for RawIntoIter<T, A>
+where
+    T: Sync,
+    A: Sync,
+{
+}
+
+#[cfg(feature = "nightly")]
+unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawIntoIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        unsafe {
+            // Drop all remaining elements
+            self.iter.drop_elements();
+
+            // Free the table
+            if let Some((ptr, layout, ref alloc)) = self.allocation {
+                alloc.deallocate(ptr, layout);
+            }
+        }
+    }
+}
+#[cfg(not(feature = "nightly"))]
+impl<T, A: Allocator> Drop for RawIntoIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        unsafe {
+            // Drop all remaining elements
+            self.iter.drop_elements();
+
+            // Free the table
+            if let Some((ptr, layout, ref alloc)) = self.allocation {
+                alloc.deallocate(ptr, layout);
+            }
+        }
+    }
+}
+
+impl<T, A: Allocator> Iterator for RawIntoIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<T> {
+        unsafe { Some(self.iter.next()?.read()) }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<T, A: Allocator> ExactSizeIterator for RawIntoIter<T, A> {}
+impl<T, A: Allocator> FusedIterator for RawIntoIter<T, A> {}
+
+/// Iterator which consumes elements without freeing the table storage.
+pub struct RawDrain<'a, T, A: Allocator = Global> {
+    iter: RawIter<T>,
+
+    // The table is moved into the iterator for the duration of the drain. This
+    // ensures that an empty table is left if the drain iterator is leaked
+    // without dropping.
+    table: RawTableInner,
+    orig_table: NonNull<RawTableInner>,
+
+    // We don't use a &'a mut RawTable<T> because we want RawDrain to be
+    // covariant over T.
+    marker: PhantomData<&'a RawTable<T, A>>,
+}
+
+impl<T, A: Allocator> RawDrain<'_, T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn iter(&self) -> RawIter<T> {
+        self.iter.clone()
+    }
+}
+
+unsafe impl<T, A: Allocator> Send for RawDrain<'_, T, A>
+where
+    T: Send,
+    A: Send,
+{
+}
+unsafe impl<T, A: Allocator> Sync for RawDrain<'_, T, A>
+where
+    T: Sync,
+    A: Sync,
+{
+}
+
+impl<T, A: Allocator> Drop for RawDrain<'_, T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        unsafe {
+            // Drop all remaining elements. Note that this may panic.
+            self.iter.drop_elements();
+
+            // Reset the contents of the table now that all elements have been
+            // dropped.
+            self.table.clear_no_drop();
+
+            // Move the now empty table back to its original location.
+            self.orig_table
+                .as_ptr()
+                .copy_from_nonoverlapping(&self.table, 1);
+        }
+    }
+}
+
+impl<T, A: Allocator> Iterator for RawDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<T> {
+        unsafe {
+            let item = self.iter.next()?;
+            Some(item.read())
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<T, A: Allocator> ExactSizeIterator for RawDrain<'_, T, A> {}
+impl<T, A: Allocator> FusedIterator for RawDrain<'_, T, A> {}
+
+/// Iterator over occupied buckets that could match a given hash.
+///
+/// `RawTable` only stores 7 bits of the hash value, so this iterator may return
+/// items that have a hash value different than the one provided. You should
+/// always validate the returned values before using them.
+///
+/// For maximum flexibility this iterator is not bound by a lifetime, but you
+/// must observe several rules when using it:
+/// - You must not free the hash table while iterating (including via growing/shrinking).
+/// - It is fine to erase a bucket that has been yielded by the iterator.
+/// - Erasing a bucket that has not yet been yielded by the iterator may still
+///   result in the iterator yielding that bucket.
+/// - It is unspecified whether an element inserted after the iterator was
+///   created will be yielded by that iterator.
+/// - The order in which the iterator yields buckets is unspecified and may
+///   change in the future.
+pub struct RawIterHash<T> {
+    inner: RawIterHashInner,
+    _marker: PhantomData<T>,
+}
+
+struct RawIterHashInner {
+    // See `RawTableInner`'s corresponding fields for details.
+    // We can't store a `*const RawTableInner` as it would get
+    // invalidated by the user calling `&mut` methods on `RawTable`.
+    bucket_mask: usize,
+    ctrl: NonNull<u8>,
+
+    // The top 7 bits of the hash.
+    h2_hash: u8,
+
+    // The sequence of groups to probe in the search.
+    probe_seq: ProbeSeq,
+
+    group: Group,
+
+    // The elements within the group with a matching h2-hash.
+    bitmask: BitMaskIter,
+}
+
+impl<T> RawIterHash<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[cfg(feature = "raw")]
+    unsafe fn new<A: Allocator>(table: &RawTable<T, A>, hash: u64) -> Self {
+        RawIterHash {
+            inner: RawIterHashInner::new(&table.table, hash),
+            _marker: PhantomData,
+        }
+    }
+}
+impl RawIterHashInner {
+    #[cfg_attr(feature = "inline-more", inline)]
+    #[cfg(feature = "raw")]
+    unsafe fn new(table: &RawTableInner, hash: u64) -> Self {
+        let h2_hash = h2(hash);
+        let probe_seq = table.probe_seq(hash);
+        let group = Group::load(table.ctrl(probe_seq.pos));
+        let bitmask = group.match_byte(h2_hash).into_iter();
+
+        RawIterHashInner {
+            bucket_mask: table.bucket_mask,
+            ctrl: table.ctrl,
+            h2_hash,
+            probe_seq,
+            group,
+            bitmask,
+        }
+    }
+}
+
+impl<T> Iterator for RawIterHash<T> {
+    type Item = Bucket<T>;
+
+    fn next(&mut self) -> Option<Bucket<T>> {
+        unsafe {
+            match self.inner.next() {
+                Some(index) => {
+                    // Can't use `RawTable::bucket` here as we don't have
+                    // an actual `RawTable` reference to use.
+                    debug_assert!(index <= self.inner.bucket_mask);
+                    let bucket = Bucket::from_base_index(self.inner.ctrl.cast(), index);
+                    Some(bucket)
+                }
+                None => None,
+            }
+        }
+    }
+}
+
+impl Iterator for RawIterHashInner {
+    type Item = usize;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        unsafe {
+            loop {
+                if let Some(bit) = self.bitmask.next() {
+                    let index = (self.probe_seq.pos + bit) & self.bucket_mask;
+                    return Some(index);
+                }
+                if likely(self.group.match_empty().any_bit_set()) {
+                    return None;
+                }
+                self.probe_seq.move_next(self.bucket_mask);
+
+                // Can't use `RawTableInner::ctrl` here as we don't have
+                // an actual `RawTableInner` reference to use.
+                let index = self.probe_seq.pos;
+                debug_assert!(index < self.bucket_mask + 1 + Group::WIDTH);
+                let group_ctrl = self.ctrl.as_ptr().add(index);
+
+                self.group = Group::load(group_ctrl);
+                self.bitmask = self.group.match_byte(self.h2_hash).into_iter();
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test_map {
+    use super::*;
+
+    fn rehash_in_place<T>(table: &mut RawTable<T>, hasher: impl Fn(&T) -> u64) {
+        unsafe {
+            table.table.rehash_in_place(
+                &|table, index| hasher(table.bucket::<T>(index).as_ref()),
+                mem::size_of::<T>(),
+                if mem::needs_drop::<T>() {
+                    Some(mem::transmute(ptr::drop_in_place::<T> as unsafe fn(*mut T)))
+                } else {
+                    None
+                },
+            );
+        }
+    }
+
+    #[test]
+    fn rehash() {
+        let mut table = RawTable::new();
+        let hasher = |i: &u64| *i;
+        for i in 0..100 {
+            table.insert(i, i, hasher);
+        }
+
+        for i in 0..100 {
+            unsafe {
+                assert_eq!(table.find(i, |x| *x == i).map(|b| b.read()), Some(i));
+            }
+            assert!(table.find(i + 100, |x| *x == i + 100).is_none());
+        }
+
+        rehash_in_place(&mut table, hasher);
+
+        for i in 0..100 {
+            unsafe {
+                assert_eq!(table.find(i, |x| *x == i).map(|b| b.read()), Some(i));
+            }
+            assert!(table.find(i + 100, |x| *x == i + 100).is_none());
+        }
+    }
+
+    /// CHECKING THAT WE ARE NOT TRYING TO READ THE MEMORY OF
+    /// AN UNINITIALIZED TABLE DURING THE DROP
+    #[test]
+    fn test_drop_uninitialized() {
+        use ::alloc::vec::Vec;
+
+        let table = unsafe {
+            // SAFETY: The `buckets` is power of two and we're not
+            // trying to actually use the returned RawTable.
+            RawTable::<(u64, Vec<i32>)>::new_uninitialized(Global, 8, Fallibility::Infallible)
+                .unwrap()
+        };
+        drop(table);
+    }
+
+    /// CHECKING THAT WE DON'T TRY TO DROP DATA IF THE `ITEMS`
+    /// ARE ZERO, EVEN IF WE HAVE `FULL` CONTROL BYTES.
+    #[test]
+    fn test_drop_zero_items() {
+        use ::alloc::vec::Vec;
+        unsafe {
+            // SAFETY: The `buckets` is power of two and we're not
+            // trying to actually use the returned RawTable.
+            let table =
+                RawTable::<(u64, Vec<i32>)>::new_uninitialized(Global, 8, Fallibility::Infallible)
+                    .unwrap();
+
+            // WE SIMULATE, AS IT WERE, A FULL TABLE.
+
+            // SAFETY: We checked that the table is allocated and therefore the table already has
+            // `self.bucket_mask + 1 + Group::WIDTH` number of control bytes (see TableLayout::calculate_layout_for)
+            // so writing `table.table.num_ctrl_bytes() == bucket_mask + 1 + Group::WIDTH` bytes is safe.
+            table
+                .table
+                .ctrl(0)
+                .write_bytes(EMPTY, table.table.num_ctrl_bytes());
+
+            // SAFETY: table.capacity() is guaranteed to be smaller than table.buckets()
+            table.table.ctrl(0).write_bytes(0, table.capacity());
+
+            // Fix up the trailing control bytes. See the comments in set_ctrl
+            // for the handling of tables smaller than the group width.
+            if table.buckets() < Group::WIDTH {
+                // SAFETY: We have `self.bucket_mask + 1 + Group::WIDTH` number of control bytes,
+                // so copying `self.buckets() == self.bucket_mask + 1` bytes with offset equal to
+                // `Group::WIDTH` is safe
+                table
+                    .table
+                    .ctrl(0)
+                    .copy_to(table.table.ctrl(Group::WIDTH), table.table.buckets());
+            } else {
+                // SAFETY: We have `self.bucket_mask + 1 + Group::WIDTH` number of
+                // control bytes,so copying `Group::WIDTH` bytes with offset equal
+                // to `self.buckets() == self.bucket_mask + 1` is safe
+                table
+                    .table
+                    .ctrl(0)
+                    .copy_to(table.table.ctrl(table.table.buckets()), Group::WIDTH);
+            }
+            drop(table);
+        }
+    }
+
+    /// CHECKING THAT WE DON'T TRY TO DROP DATA IF THE `ITEMS`
+    /// ARE ZERO, EVEN IF WE HAVE `FULL` CONTROL BYTES.
+    #[test]
+    fn test_catch_panic_clone_from() {
+        use ::alloc::sync::Arc;
+        use ::alloc::vec::Vec;
+        use allocator_api2::alloc::{AllocError, Allocator, Global};
+        use core::sync::atomic::{AtomicI8, Ordering};
+        use std::thread;
+
+        struct MyAllocInner {
+            drop_count: Arc<AtomicI8>,
+        }
+
+        #[derive(Clone)]
+        struct MyAlloc {
+            _inner: Arc<MyAllocInner>,
+        }
+
+        impl Drop for MyAllocInner {
+            fn drop(&mut self) {
+                println!("MyAlloc freed.");
+                self.drop_count.fetch_sub(1, Ordering::SeqCst);
+            }
+        }
+
+        unsafe impl Allocator for MyAlloc {
+            fn allocate(&self, layout: Layout) -> std::result::Result<NonNull<[u8]>, AllocError> {
+                let g = Global;
+                g.allocate(layout)
+            }
+
+            unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+                let g = Global;
+                g.deallocate(ptr, layout)
+            }
+        }
+
+        const DISARMED: bool = false;
+        const ARMED: bool = true;
+
+        struct CheckedCloneDrop {
+            panic_in_clone: bool,
+            dropped: bool,
+            need_drop: Vec<u64>,
+        }
+
+        impl Clone for CheckedCloneDrop {
+            fn clone(&self) -> Self {
+                if self.panic_in_clone {
+                    panic!("panic in clone")
+                }
+                Self {
+                    panic_in_clone: self.panic_in_clone,
+                    dropped: self.dropped,
+                    need_drop: self.need_drop.clone(),
+                }
+            }
+        }
+
+        impl Drop for CheckedCloneDrop {
+            fn drop(&mut self) {
+                if self.dropped {
+                    panic!("double drop");
+                }
+                self.dropped = true;
+            }
+        }
+
+        let dropped: Arc<AtomicI8> = Arc::new(AtomicI8::new(2));
+
+        let mut table = RawTable::new_in(MyAlloc {
+            _inner: Arc::new(MyAllocInner {
+                drop_count: dropped.clone(),
+            }),
+        });
+
+        for (idx, panic_in_clone) in core::iter::repeat(DISARMED).take(7).enumerate() {
+            let idx = idx as u64;
+            table.insert(
+                idx,
+                (
+                    idx,
+                    CheckedCloneDrop {
+                        panic_in_clone,
+                        dropped: false,
+                        need_drop: vec![idx],
+                    },
+                ),
+                |(k, _)| *k,
+            );
+        }
+
+        assert_eq!(table.len(), 7);
+
+        thread::scope(|s| {
+            let result = s.spawn(|| {
+                let armed_flags = [
+                    DISARMED, DISARMED, ARMED, DISARMED, DISARMED, DISARMED, DISARMED,
+                ];
+                let mut scope_table = RawTable::new_in(MyAlloc {
+                    _inner: Arc::new(MyAllocInner {
+                        drop_count: dropped.clone(),
+                    }),
+                });
+                for (idx, &panic_in_clone) in armed_flags.iter().enumerate() {
+                    let idx = idx as u64;
+                    scope_table.insert(
+                        idx,
+                        (
+                            idx,
+                            CheckedCloneDrop {
+                                panic_in_clone,
+                                dropped: false,
+                                need_drop: vec![idx + 100],
+                            },
+                        ),
+                        |(k, _)| *k,
+                    );
+                }
+                table.clone_from(&scope_table);
+            });
+            assert!(result.join().is_err());
+        });
+
+        // Let's check that all iterators work fine and do not return elements
+        // (especially `RawIterRange`, which does not depend on the number of
+        // elements in the table, but looks directly at the control bytes)
+        //
+        // SAFETY: We know for sure that `RawTable` will outlive
+        // the returned `RawIter / RawIterRange` iterator.
+        assert_eq!(table.len(), 0);
+        assert_eq!(unsafe { table.iter().count() }, 0);
+        assert_eq!(unsafe { table.iter().iter.count() }, 0);
+
+        for idx in 0..table.buckets() {
+            let idx = idx as u64;
+            assert!(
+                table.find(idx, |(k, _)| *k == idx).is_none(),
+                "Index: {idx}"
+            );
+        }
+
+        // All allocator clones should already be dropped.
+        assert_eq!(dropped.load(Ordering::SeqCst), 1);
+    }
+}
diff --git a/vendor/hashbrown/src/raw/neon.rs b/vendor/hashbrown/src/raw/neon.rs
new file mode 100644
index 0000000..44e82d5
--- /dev/null
+++ b/vendor/hashbrown/src/raw/neon.rs
@@ -0,0 +1,124 @@
+use super::bitmask::BitMask;
+use super::EMPTY;
+use core::arch::aarch64 as neon;
+use core::mem;
+use core::num::NonZeroU64;
+
+pub(crate) type BitMaskWord = u64;
+pub(crate) type NonZeroBitMaskWord = NonZeroU64;
+pub(crate) const BITMASK_STRIDE: usize = 8;
+pub(crate) const BITMASK_MASK: BitMaskWord = !0;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = 0x8080_8080_8080_8080;
+
+/// Abstraction over a group of control bytes which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 64-bit NEON value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(neon::uint8x8_t);
+
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty bytes, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    pub(crate) const fn static_empty() -> &'static [u8; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedBytes {
+            _align: [Group; 0],
+            bytes: [u8; Group::WIDTH],
+        }
+        const ALIGNED_BYTES: AlignedBytes = AlignedBytes {
+            _align: [],
+            bytes: [EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_BYTES.bytes
+    }
+
+    /// Loads a group of bytes starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
+        Group(neon::vld1_u8(ptr))
+    }
+
+    /// Loads a group of bytes starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const u8) -> Self {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        Group(neon::vld1_u8(ptr))
+    }
+
+    /// Stores the group of bytes to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut u8) {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        neon::vst1_u8(ptr, self.0);
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which *may*
+    /// have the given value.
+    #[inline]
+    pub(crate) fn match_byte(self, byte: u8) -> BitMask {
+        unsafe {
+            let cmp = neon::vceq_u8(self.0, neon::vdup_n_u8(byte));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        self.match_byte(EMPTY)
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        unsafe {
+            let cmp = neon::vcltz_s8(neon::vreinterpret_s8_u8(self.0));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(self) -> BitMask {
+        unsafe {
+            let cmp = neon::vcgez_s8(neon::vreinterpret_s8_u8(self.0));
+            BitMask(neon::vget_lane_u64(neon::vreinterpret_u64_u8(cmp), 0))
+        }
+    }
+
+    /// Performs the following transformation on all bytes in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let special = 0 > byte = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        unsafe {
+            let special = neon::vcltz_s8(neon::vreinterpret_s8_u8(self.0));
+            Group(neon::vorr_u8(special, neon::vdup_n_u8(0x80)))
+        }
+    }
+}
diff --git a/vendor/hashbrown/src/raw/sse2.rs b/vendor/hashbrown/src/raw/sse2.rs
new file mode 100644
index 0000000..956ba5d
--- /dev/null
+++ b/vendor/hashbrown/src/raw/sse2.rs
@@ -0,0 +1,149 @@
+use super::bitmask::BitMask;
+use super::EMPTY;
+use core::mem;
+use core::num::NonZeroU16;
+
+#[cfg(target_arch = "x86")]
+use core::arch::x86;
+#[cfg(target_arch = "x86_64")]
+use core::arch::x86_64 as x86;
+
+pub(crate) type BitMaskWord = u16;
+pub(crate) type NonZeroBitMaskWord = NonZeroU16;
+pub(crate) const BITMASK_STRIDE: usize = 1;
+pub(crate) const BITMASK_MASK: BitMaskWord = 0xffff;
+pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
+
+/// Abstraction over a group of control bytes which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 128-bit SSE value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(x86::__m128i);
+
+// FIXME: https://github.com/rust-lang/rust-clippy/issues/3859
+#[allow(clippy::use_self)]
+impl Group {
+    /// Number of bytes in the group.
+    pub(crate) const WIDTH: usize = mem::size_of::<Self>();
+
+    /// Returns a full group of empty bytes, suitable for use as the initial
+    /// value for an empty hash table.
+    ///
+    /// This is guaranteed to be aligned to the group size.
+    #[inline]
+    #[allow(clippy::items_after_statements)]
+    pub(crate) const fn static_empty() -> &'static [u8; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedBytes {
+            _align: [Group; 0],
+            bytes: [u8; Group::WIDTH],
+        }
+        const ALIGNED_BYTES: AlignedBytes = AlignedBytes {
+            _align: [],
+            bytes: [EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_BYTES.bytes
+    }
+
+    /// Loads a group of bytes starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
+        Group(x86::_mm_loadu_si128(ptr.cast()))
+    }
+
+    /// Loads a group of bytes starting at the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn load_aligned(ptr: *const u8) -> Self {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        Group(x86::_mm_load_si128(ptr.cast()))
+    }
+
+    /// Stores the group of bytes to the given address, which must be
+    /// aligned to `mem::align_of::<Group>()`.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)]
+    pub(crate) unsafe fn store_aligned(self, ptr: *mut u8) {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        x86::_mm_store_si128(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which have
+    /// the given value.
+    #[inline]
+    pub(crate) fn match_byte(self, byte: u8) -> BitMask {
+        #[allow(
+            clippy::cast_possible_wrap, // byte: u8 as i8
+            // byte: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            let cmp = x86::_mm_cmpeq_epi8(self.0, x86::_mm_set1_epi8(byte as i8));
+            BitMask(x86::_mm_movemask_epi8(cmp) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        self.match_byte(EMPTY)
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        #[allow(
+            // byte: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            // A byte is EMPTY or DELETED iff the high bit is set
+            BitMask(x86::_mm_movemask_epi8(self.0) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(&self) -> BitMask {
+        self.match_empty_or_deleted().invert()
+    }
+
+    /// Performs the following transformation on all bytes in the group:
+    /// - `EMPTY => EMPTY`
+    /// - `DELETED => EMPTY`
+    /// - `FULL => DELETED`
+    #[inline]
+    pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+        // Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
+        // and high_bit = 0 (FULL) to 1000_0000
+        //
+        // Here's this logic expanded to concrete values:
+        //   let special = 0 > byte = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        #[allow(
+            clippy::cast_possible_wrap, // byte: 0x80_u8 as i8
+        )]
+        unsafe {
+            let zero = x86::_mm_setzero_si128();
+            let special = x86::_mm_cmpgt_epi8(zero, self.0);
+            Group(x86::_mm_or_si128(
+                special,
+                x86::_mm_set1_epi8(0x80_u8 as i8),
+            ))
+        }
+    }
+}
diff --git a/vendor/hashbrown/src/rustc_entry.rs b/vendor/hashbrown/src/rustc_entry.rs
new file mode 100644
index 0000000..defbd4b
--- /dev/null
+++ b/vendor/hashbrown/src/rustc_entry.rs
@@ -0,0 +1,630 @@
+use self::RustcEntry::*;
+use crate::map::{make_hash, Drain, HashMap, IntoIter, Iter, IterMut};
+use crate::raw::{Allocator, Bucket, Global, RawTable};
+use core::fmt::{self, Debug};
+use core::hash::{BuildHasher, Hash};
+use core::mem;
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Gets the given key's corresponding entry in the map for in-place manipulation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut letters = HashMap::new();
+    ///
+    /// for ch in "a short treatise on fungi".chars() {
+    ///     let counter = letters.rustc_entry(ch).or_insert(0);
+    ///     *counter += 1;
+    /// }
+    ///
+    /// assert_eq!(letters[&'s'], 2);
+    /// assert_eq!(letters[&'t'], 3);
+    /// assert_eq!(letters[&'u'], 1);
+    /// assert_eq!(letters.get(&'y'), None);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_entry(&mut self, key: K) -> RustcEntry<'_, K, V, A> {
+        let hash = make_hash(&self.hash_builder, &key);
+        if let Some(elem) = self.table.find(hash, |q| q.0.eq(&key)) {
+            RustcEntry::Occupied(RustcOccupiedEntry {
+                key: Some(key),
+                elem,
+                table: &mut self.table,
+            })
+        } else {
+            // Ideally we would put this in VacantEntry::insert, but Entry is not
+            // generic over the BuildHasher and adding a generic parameter would be
+            // a breaking change.
+            self.reserve(1);
+
+            RustcEntry::Vacant(RustcVacantEntry {
+                hash,
+                key,
+                table: &mut self.table,
+            })
+        }
+    }
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied.
+///
+/// This `enum` is constructed from the [`rustc_entry`] method on [`HashMap`].
+///
+/// [`HashMap`]: struct.HashMap.html
+/// [`rustc_entry`]: struct.HashMap.html#method.rustc_entry
+pub enum RustcEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    /// An occupied entry.
+    Occupied(RustcOccupiedEntry<'a, K, V, A>),
+
+    /// A vacant entry.
+    Vacant(RustcVacantEntry<'a, K, V, A>),
+}
+
+impl<K: Debug, V: Debug, A: Allocator> Debug for RustcEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(),
+            Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(),
+        }
+    }
+}
+
+/// A view into an occupied entry in a `HashMap`.
+/// It is part of the [`RustcEntry`] enum.
+///
+/// [`RustcEntry`]: enum.RustcEntry.html
+pub struct RustcOccupiedEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    key: Option<K>,
+    elem: Bucket<(K, V)>,
+    table: &'a mut RawTable<(K, V), A>,
+}
+
+unsafe impl<K, V, A> Send for RustcOccupiedEntry<'_, K, V, A>
+where
+    K: Send,
+    V: Send,
+    A: Allocator + Send,
+{
+}
+unsafe impl<K, V, A> Sync for RustcOccupiedEntry<'_, K, V, A>
+where
+    K: Sync,
+    V: Sync,
+    A: Allocator + Sync,
+{
+}
+
+impl<K: Debug, V: Debug, A: Allocator> Debug for RustcOccupiedEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedEntry")
+            .field("key", self.key())
+            .field("value", self.get())
+            .finish()
+    }
+}
+
+/// A view into a vacant entry in a `HashMap`.
+/// It is part of the [`RustcEntry`] enum.
+///
+/// [`RustcEntry`]: enum.RustcEntry.html
+pub struct RustcVacantEntry<'a, K, V, A = Global>
+where
+    A: Allocator,
+{
+    hash: u64,
+    key: K,
+    table: &'a mut RawTable<(K, V), A>,
+}
+
+impl<K: Debug, V, A: Allocator> Debug for RustcVacantEntry<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VacantEntry").field(self.key()).finish()
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcEntry<'a, K, V, A> {
+    /// Sets the value of the entry, and returns a RustcOccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// let entry = map.rustc_entry("horseyland").insert(37);
+    ///
+    /// assert_eq!(entry.key(), &"horseyland");
+    /// ```
+    pub fn insert(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
+        match self {
+            Vacant(entry) => entry.insert_entry(value),
+            Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the default if empty, and returns
+    /// a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.rustc_entry("poneyland").or_insert(3);
+    /// assert_eq!(map["poneyland"], 3);
+    ///
+    /// *map.rustc_entry("poneyland").or_insert(10) *= 2;
+    /// assert_eq!(map["poneyland"], 6);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self, default: V) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(default),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the default function if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, String> = HashMap::new();
+    /// let s = "hoho".to_string();
+    ///
+    /// map.rustc_entry("poneyland").or_insert_with(|| s);
+    ///
+    /// assert_eq!(map["poneyland"], "hoho".to_string());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(default()),
+        }
+    }
+
+    /// Returns a reference to this entry's key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        match *self {
+            Occupied(ref entry) => entry.key(),
+            Vacant(ref entry) => entry.key(),
+        }
+    }
+
+    /// Provides in-place mutable access to an occupied entry before any
+    /// potential inserts into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// map.rustc_entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 42);
+    ///
+    /// map.rustc_entry("poneyland")
+    ///    .and_modify(|e| { *e += 1 })
+    ///    .or_insert(42);
+    /// assert_eq!(map["poneyland"], 43);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn and_modify<F>(self, f: F) -> Self
+    where
+        F: FnOnce(&mut V),
+    {
+        match self {
+            Occupied(mut entry) => {
+                f(entry.get_mut());
+                Occupied(entry)
+            }
+            Vacant(entry) => Vacant(entry),
+        }
+    }
+}
+
+impl<'a, K, V: Default, A: Allocator> RustcEntry<'a, K, V, A> {
+    /// Ensures a value is in the entry by inserting the default value if empty,
+    /// and returns a mutable reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # fn main() {
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_default();
+    ///
+    /// assert_eq!(map["poneyland"], None);
+    /// # }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_default(self) -> &'a mut V
+    where
+        K: Hash,
+    {
+        match self {
+            Occupied(entry) => entry.into_mut(),
+            Vacant(entry) => entry.insert(Default::default()),
+        }
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcOccupiedEntry<'a, K, V, A> {
+    /// Gets a reference to the key in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
+    }
+
+    /// Take the ownership of the key and value from the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     // We delete the entry from the map.
+    ///     o.remove_entry();
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove_entry(self) -> (K, V) {
+        unsafe { self.table.remove(self.elem).0 }
+    }
+
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.get(), &12);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &V {
+        unsafe { &self.elem.as_ref().1 }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    ///
+    /// If you need a reference to the `RustcOccupiedEntry` which may outlive the
+    /// destruction of the `RustcEntry` value, see [`into_mut`].
+    ///
+    /// [`into_mut`]: #method.into_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
+    ///     *o.get_mut() += 10;
+    ///     assert_eq!(*o.get(), 22);
+    ///
+    ///     // We can use the same RustcEntry multiple times.
+    ///     *o.get_mut() += 2;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 24);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Converts the RustcOccupiedEntry into a mutable reference to the value in the entry
+    /// with a lifetime bound to the map itself.
+    ///
+    /// If you need multiple references to the `RustcOccupiedEntry`, see [`get_mut`].
+    ///
+    /// [`get_mut`]: #method.get_mut
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// assert_eq!(map["poneyland"], 12);
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     *o.into_mut() += 10;
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 22);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut self.elem.as_mut().1 }
+    }
+
+    /// Sets the value of the entry, and returns the entry's old value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(mut o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.insert(15), 12);
+    /// }
+    ///
+    /// assert_eq!(map["poneyland"], 15);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// map.rustc_entry("poneyland").or_insert(12);
+    ///
+    /// if let RustcEntry::Occupied(o) = map.rustc_entry("poneyland") {
+    ///     assert_eq!(o.remove(), 12);
+    /// }
+    ///
+    /// assert_eq!(map.contains_key("poneyland"), false);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> V {
+        self.remove_entry().1
+    }
+
+    /// Replaces the entry, returning the old key and value. The new key in the hash map will be
+    /// the key used to create this entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{RustcEntry, HashMap};
+    /// use std::rc::Rc;
+    ///
+    /// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
+    /// map.insert(Rc::new("Stringthing".to_string()), 15);
+    ///
+    /// let my_key = Rc::new("Stringthing".to_string());
+    ///
+    /// if let RustcEntry::Occupied(entry) = map.rustc_entry(my_key) {
+    ///     // Also replace the key with a handle to our other key.
+    ///     let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
+    /// }
+    ///
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_entry(self, value: V) -> (K, V) {
+        let entry = unsafe { self.elem.as_mut() };
+
+        let old_key = mem::replace(&mut entry.0, self.key.unwrap());
+        let old_value = mem::replace(&mut entry.1, value);
+
+        (old_key, old_value)
+    }
+
+    /// Replaces the key in the hash map with the key used to create this entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_map::{RustcEntry, HashMap};
+    /// use std::rc::Rc;
+    ///
+    /// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
+    /// let mut known_strings: Vec<Rc<String>> = Vec::new();
+    ///
+    /// // Initialise known strings, run program, etc.
+    ///
+    /// reclaim_memory(&mut map, &known_strings);
+    ///
+    /// fn reclaim_memory(map: &mut HashMap<Rc<String>, u32>, known_strings: &[Rc<String>] ) {
+    ///     for s in known_strings {
+    ///         if let RustcEntry::Occupied(entry) = map.rustc_entry(s.clone()) {
+    ///             // Replaces the entry's key with our version of it in `known_strings`.
+    ///             entry.replace_key();
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace_key(self) -> K {
+        let entry = unsafe { self.elem.as_mut() };
+        mem::replace(&mut entry.0, self.key.unwrap())
+    }
+}
+
+impl<'a, K, V, A: Allocator> RustcVacantEntry<'a, K, V, A> {
+    /// Gets a reference to the key that would be used when inserting a value
+    /// through the `RustcVacantEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    /// assert_eq!(map.rustc_entry("poneyland").key(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+
+    /// Take ownership of the key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
+    ///     v.into_key();
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    /// Sets the value of the entry with the RustcVacantEntry's key,
+    /// and returns a mutable reference to it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(o) = map.rustc_entry("poneyland") {
+    ///     o.insert(37);
+    /// }
+    /// assert_eq!(map["poneyland"], 37);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self, value: V) -> &'a mut V {
+        unsafe {
+            let bucket = self.table.insert_no_grow(self.hash, (self.key, value));
+            &mut bucket.as_mut().1
+        }
+    }
+
+    /// Sets the value of the entry with the RustcVacantEntry's key,
+    /// and returns a RustcOccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashMap;
+    /// use hashbrown::hash_map::RustcEntry;
+    ///
+    /// let mut map: HashMap<&str, u32> = HashMap::new();
+    ///
+    /// if let RustcEntry::Vacant(v) = map.rustc_entry("poneyland") {
+    ///     let o = v.insert_entry(37);
+    ///     assert_eq!(o.get(), &37);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_entry(self, value: V) -> RustcOccupiedEntry<'a, K, V, A> {
+        let bucket = unsafe { self.table.insert_no_grow(self.hash, (self.key, value)) };
+        RustcOccupiedEntry {
+            key: None,
+            elem: bucket,
+            table: self.table,
+        }
+    }
+}
+
+impl<K, V> IterMut<'_, K, V> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}
+
+impl<K, V> IntoIter<K, V> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}
+
+impl<K, V> Drain<'_, K, V> {
+    /// Returns a iterator of references over the remaining items.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn rustc_iter(&self) -> Iter<'_, K, V> {
+        self.iter()
+    }
+}
diff --git a/vendor/hashbrown/src/scopeguard.rs b/vendor/hashbrown/src/scopeguard.rs
new file mode 100644
index 0000000..382d060
--- /dev/null
+++ b/vendor/hashbrown/src/scopeguard.rs
@@ -0,0 +1,72 @@
+// Extracted from the scopeguard crate
+use core::{
+    mem::ManuallyDrop,
+    ops::{Deref, DerefMut},
+    ptr,
+};
+
+pub struct ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    dropfn: F,
+    value: T,
+}
+
+#[inline]
+pub fn guard<T, F>(value: T, dropfn: F) -> ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    ScopeGuard { dropfn, value }
+}
+
+impl<T, F> ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    pub fn into_inner(guard: Self) -> T {
+        // Cannot move out of Drop-implementing types, so
+        // ptr::read the value out of a ManuallyDrop<Self>
+        // Don't use mem::forget as that might invalidate value
+        let guard = ManuallyDrop::new(guard);
+        unsafe {
+            let value = ptr::read(&guard.value);
+            // read the closure so that it is dropped
+            let _ = ptr::read(&guard.dropfn);
+            value
+        }
+    }
+}
+
+impl<T, F> Deref for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    type Target = T;
+    #[inline]
+    fn deref(&self) -> &T {
+        &self.value
+    }
+}
+
+impl<T, F> DerefMut for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    fn deref_mut(&mut self) -> &mut T {
+        &mut self.value
+    }
+}
+
+impl<T, F> Drop for ScopeGuard<T, F>
+where
+    F: FnMut(&mut T),
+{
+    #[inline]
+    fn drop(&mut self) {
+        (self.dropfn)(&mut self.value);
+    }
+}
diff --git a/vendor/hashbrown/src/set.rs b/vendor/hashbrown/src/set.rs
new file mode 100644
index 0000000..0b8d984
--- /dev/null
+++ b/vendor/hashbrown/src/set.rs
@@ -0,0 +1,2899 @@
+#[cfg(feature = "raw")]
+use crate::raw::RawTable;
+use crate::{Equivalent, TryReserveError};
+use alloc::borrow::ToOwned;
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use core::iter::{Chain, FromIterator, FusedIterator};
+use core::ops::{BitAnd, BitOr, BitXor, Sub};
+
+use super::map::{self, DefaultHashBuilder, ExtractIfInner, HashMap, Keys};
+use crate::raw::{Allocator, Global};
+
+// Future Optimization (FIXME!)
+// =============================
+//
+// Iteration over zero sized values is a noop. There is no need
+// for `bucket.val` in the case of HashSet. I suppose we would need HKT
+// to get rid of it properly.
+
+/// A hash set implemented as a `HashMap` where the value is `()`.
+///
+/// As with the [`HashMap`] type, a `HashSet` requires that the elements
+/// implement the [`Eq`] and [`Hash`] traits. This can frequently be achieved by
+/// using `#[derive(PartialEq, Eq, Hash)]`. If you implement these yourself,
+/// it is important that the following property holds:
+///
+/// ```text
+/// k1 == k2 -> hash(k1) == hash(k2)
+/// ```
+///
+/// In other words, if two keys are equal, their hashes must be equal.
+///
+///
+/// It is a logic error for an item to be modified in such a way that the
+/// item's hash, as determined by the [`Hash`] trait, or its equality, as
+/// determined by the [`Eq`] trait, changes while it is in the set. This is
+/// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or
+/// unsafe code.
+///
+/// It is also a logic error for the [`Hash`] implementation of a key to panic.
+/// This is generally only possible if the trait is implemented manually. If a
+/// panic does occur then the contents of the `HashSet` may become corrupted and
+/// some items may be dropped from the table.
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::HashSet;
+/// // Type inference lets us omit an explicit type signature (which
+/// // would be `HashSet<String>` in this example).
+/// let mut books = HashSet::new();
+///
+/// // Add some books.
+/// books.insert("A Dance With Dragons".to_string());
+/// books.insert("To Kill a Mockingbird".to_string());
+/// books.insert("The Odyssey".to_string());
+/// books.insert("The Great Gatsby".to_string());
+///
+/// // Check for a specific one.
+/// if !books.contains("The Winds of Winter") {
+///     println!("We have {} books, but The Winds of Winter ain't one.",
+///              books.len());
+/// }
+///
+/// // Remove a book.
+/// books.remove("The Odyssey");
+///
+/// // Iterate over everything.
+/// for book in &books {
+///     println!("{}", book);
+/// }
+/// ```
+///
+/// The easiest way to use `HashSet` with a custom type is to derive
+/// [`Eq`] and [`Hash`]. We must also derive [`PartialEq`]. This will in the
+/// future be implied by [`Eq`].
+///
+/// ```
+/// use hashbrown::HashSet;
+/// #[derive(Hash, Eq, PartialEq, Debug)]
+/// struct Viking {
+///     name: String,
+///     power: usize,
+/// }
+///
+/// let mut vikings = HashSet::new();
+///
+/// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
+/// vikings.insert(Viking { name: "Einar".to_string(), power: 9 });
+/// vikings.insert(Viking { name: "Olaf".to_string(), power: 4 });
+/// vikings.insert(Viking { name: "Harald".to_string(), power: 8 });
+///
+/// // Use derived implementation to print the vikings.
+/// for x in &vikings {
+///     println!("{:?}", x);
+/// }
+/// ```
+///
+/// A `HashSet` with fixed list of elements can be initialized from an array:
+///
+/// ```
+/// use hashbrown::HashSet;
+///
+/// let viking_names: HashSet<&'static str> =
+///     [ "Einar", "Olaf", "Harald" ].iter().cloned().collect();
+/// // use the values stored in the set
+/// ```
+///
+/// [`Cell`]: https://doc.rust-lang.org/std/cell/struct.Cell.html
+/// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+/// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+/// [`HashMap`]: struct.HashMap.html
+/// [`PartialEq`]: https://doc.rust-lang.org/std/cmp/trait.PartialEq.html
+/// [`RefCell`]: https://doc.rust-lang.org/std/cell/struct.RefCell.html
+pub struct HashSet<T, S = DefaultHashBuilder, A: Allocator = Global> {
+    pub(crate) map: HashMap<T, (), S, A>,
+}
+
+impl<T: Clone, S: Clone, A: Allocator + Clone> Clone for HashSet<T, S, A> {
+    fn clone(&self) -> Self {
+        HashSet {
+            map: self.map.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        self.map.clone_from(&source.map);
+    }
+}
+
+#[cfg(feature = "ahash")]
+impl<T> HashSet<T, DefaultHashBuilder> {
+    /// Creates an empty `HashSet`.
+    ///
+    /// The hash set is initially created with a capacity of 0, so it will not allocate until it
+    /// is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`], for example with
+    /// [`with_hasher`](HashSet::with_hasher) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let set: HashSet<i32> = HashSet::new();
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn new() -> Self {
+        Self {
+            map: HashMap::new(),
+        }
+    }
+
+    /// Creates an empty `HashSet` with the specified capacity.
+    ///
+    /// The hash set will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash set will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`], for example with
+    /// [`with_capacity_and_hasher`](HashSet::with_capacity_and_hasher) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let set: HashSet<i32> = HashSet::with_capacity(10);
+    /// assert!(set.capacity() >= 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self {
+            map: HashMap::with_capacity(capacity),
+        }
+    }
+}
+
+#[cfg(feature = "ahash")]
+impl<T: Hash + Eq, A: Allocator> HashSet<T, DefaultHashBuilder, A> {
+    /// Creates an empty `HashSet`.
+    ///
+    /// The hash set is initially created with a capacity of 0, so it will not allocate until it
+    /// is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`], for example with
+    /// [`with_hasher_in`](HashSet::with_hasher_in) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let set: HashSet<i32> = HashSet::new();
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn new_in(alloc: A) -> Self {
+        Self {
+            map: HashMap::new_in(alloc),
+        }
+    }
+
+    /// Creates an empty `HashSet` with the specified capacity.
+    ///
+    /// The hash set will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash set will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`], for example with
+    /// [`with_capacity_and_hasher_in`](HashSet::with_capacity_and_hasher_in) method.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let set: HashSet<i32> = HashSet::with_capacity(10);
+    /// assert!(set.capacity() >= 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
+        Self {
+            map: HashMap::with_capacity_in(capacity, alloc),
+        }
+    }
+}
+
+impl<T, S, A: Allocator> HashSet<T, S, A> {
+    /// Returns the number of elements the set can hold without reallocating.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let set: HashSet<i32> = HashSet::with_capacity(100);
+    /// assert!(set.capacity() >= 100);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn capacity(&self) -> usize {
+        self.map.capacity()
+    }
+
+    /// An iterator visiting all elements in arbitrary order.
+    /// The iterator element type is `&'a T`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let mut set = HashSet::new();
+    /// set.insert("a");
+    /// set.insert("b");
+    ///
+    /// // Will print in an arbitrary order.
+    /// for x in set.iter() {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn iter(&self) -> Iter<'_, T> {
+        Iter {
+            iter: self.map.keys(),
+        }
+    }
+
+    /// Returns the number of elements in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut v = HashSet::new();
+    /// assert_eq!(v.len(), 0);
+    /// v.insert(1);
+    /// assert_eq!(v.len(), 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn len(&self) -> usize {
+        self.map.len()
+    }
+
+    /// Returns `true` if the set contains no elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut v = HashSet::new();
+    /// assert!(v.is_empty());
+    /// v.insert(1);
+    /// assert!(!v.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn is_empty(&self) -> bool {
+        self.map.is_empty()
+    }
+
+    /// Clears the set, returning all elements in an iterator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// assert!(!set.is_empty());
+    ///
+    /// // print 1, 2, 3 in an arbitrary order
+    /// for i in set.drain() {
+    ///     println!("{}", i);
+    /// }
+    ///
+    /// assert!(set.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn drain(&mut self) -> Drain<'_, T, A> {
+        Drain {
+            iter: self.map.drain(),
+        }
+    }
+
+    /// Retains only the elements specified by the predicate.
+    ///
+    /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let xs = [1,2,3,4,5,6];
+    /// let mut set: HashSet<i32> = xs.iter().cloned().collect();
+    /// set.retain(|&k| k % 2 == 0);
+    /// assert_eq!(set.len(), 3);
+    /// ```
+    pub fn retain<F>(&mut self, mut f: F)
+    where
+        F: FnMut(&T) -> bool,
+    {
+        self.map.retain(|k, _| f(k));
+    }
+
+    /// Drains elements which are true under the given predicate,
+    /// and returns an iterator over the removed items.
+    ///
+    /// In other words, move all elements `e` such that `f(&e)` returns `true` out
+    /// into another iterator.
+    ///
+    /// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating
+    /// or the iteration short-circuits, then the remaining elements will be retained.
+    /// Use [`retain()`] with a negated predicate if you do not need the returned iterator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<i32> = (0..8).collect();
+    /// let drained: HashSet<i32> = set.extract_if(|v| v % 2 == 0).collect();
+    ///
+    /// let mut evens = drained.into_iter().collect::<Vec<_>>();
+    /// let mut odds = set.into_iter().collect::<Vec<_>>();
+    /// evens.sort();
+    /// odds.sort();
+    ///
+    /// assert_eq!(evens, vec![0, 2, 4, 6]);
+    /// assert_eq!(odds, vec![1, 3, 5, 7]);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F, A>
+    where
+        F: FnMut(&T) -> bool,
+    {
+        ExtractIf {
+            f,
+            inner: ExtractIfInner {
+                iter: unsafe { self.map.table.iter() },
+                table: &mut self.map.table,
+            },
+        }
+    }
+
+    /// Clears the set, removing all values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut v = HashSet::new();
+    /// v.insert(1);
+    /// v.clear();
+    /// assert!(v.is_empty());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn clear(&mut self) {
+        self.map.clear();
+    }
+}
+
+impl<T, S> HashSet<T, S, Global> {
+    /// Creates a new empty hash set which will use the given hasher to hash
+    /// keys.
+    ///
+    /// The hash set is initially created with a capacity of 0, so it will not
+    /// allocate until it is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashSet to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut set = HashSet::with_hasher(s);
+    /// set.insert(2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub const fn with_hasher(hasher: S) -> Self {
+        Self {
+            map: HashMap::with_hasher(hasher),
+        }
+    }
+
+    /// Creates an empty `HashSet` with the specified capacity, using
+    /// `hasher` to hash the keys.
+    ///
+    /// The hash set will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash set will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashSet to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut set = HashSet::with_capacity_and_hasher(10, s);
+    /// set.insert(1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> Self {
+        Self {
+            map: HashMap::with_capacity_and_hasher(capacity, hasher),
+        }
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    A: Allocator,
+{
+    /// Returns a reference to the underlying allocator.
+    #[inline]
+    pub fn allocator(&self) -> &A {
+        self.map.allocator()
+    }
+
+    /// Creates a new empty hash set which will use the given hasher to hash
+    /// keys.
+    ///
+    /// The hash set is initially created with a capacity of 0, so it will not
+    /// allocate until it is first inserted into.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashSet to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut set = HashSet::with_hasher(s);
+    /// set.insert(2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub const fn with_hasher_in(hasher: S, alloc: A) -> Self {
+        Self {
+            map: HashMap::with_hasher_in(hasher, alloc),
+        }
+    }
+
+    /// Creates an empty `HashSet` with the specified capacity, using
+    /// `hasher` to hash the keys.
+    ///
+    /// The hash set will be able to hold at least `capacity` elements without
+    /// reallocating. If `capacity` is 0, the hash set will not allocate.
+    ///
+    /// # HashDoS resistance
+    ///
+    /// The `hash_builder` normally use a fixed key by default and that does
+    /// not allow the `HashSet` to be protected against attacks such as [`HashDoS`].
+    /// Users who require HashDoS resistance should explicitly use
+    /// [`ahash::RandomState`] or [`std::collections::hash_map::RandomState`]
+    /// as the hasher when creating a [`HashSet`].
+    ///
+    /// The `hash_builder` passed should implement the [`BuildHasher`] trait for
+    /// the HashSet to be useful, see its documentation for details.
+    ///
+    /// [`HashDoS`]: https://en.wikipedia.org/wiki/Collision_attack
+    /// [`std::collections::hash_map::RandomState`]: https://doc.rust-lang.org/std/collections/hash_map/struct.RandomState.html
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let s = DefaultHashBuilder::default();
+    /// let mut set = HashSet::with_capacity_and_hasher(10, s);
+    /// set.insert(1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn with_capacity_and_hasher_in(capacity: usize, hasher: S, alloc: A) -> Self {
+        Self {
+            map: HashMap::with_capacity_and_hasher_in(capacity, hasher, alloc),
+        }
+    }
+
+    /// Returns a reference to the set's [`BuildHasher`].
+    ///
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_map::DefaultHashBuilder;
+    ///
+    /// let hasher = DefaultHashBuilder::default();
+    /// let set: HashSet<i32> = HashSet::with_hasher(hasher);
+    /// let hasher: &DefaultHashBuilder = set.hasher();
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn hasher(&self) -> &S {
+        self.map.hasher()
+    }
+}
+
+impl<T, S, A> HashSet<T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    /// Reserves capacity for at least `additional` more elements to be inserted
+    /// in the `HashSet`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity exceeds [`isize::MAX`] bytes and [`abort`] the program
+    /// in case of allocation error. Use [`try_reserve`](HashSet::try_reserve) instead
+    /// if you want to handle memory allocation failure.
+    ///
+    /// [`isize::MAX`]: https://doc.rust-lang.org/std/primitive.isize.html
+    /// [`abort`]: https://doc.rust-lang.org/alloc/alloc/fn.handle_alloc_error.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let mut set: HashSet<i32> = HashSet::new();
+    /// set.reserve(10);
+    /// assert!(set.capacity() >= 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn reserve(&mut self, additional: usize) {
+        self.map.reserve(additional);
+    }
+
+    /// Tries to reserve capacity for at least `additional` more elements to be inserted
+    /// in the given `HashSet<K,V>`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Errors
+    ///
+    /// If the capacity overflows, or the allocator reports a failure, then an error
+    /// is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let mut set: HashSet<i32> = HashSet::new();
+    /// set.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+        self.map.try_reserve(additional)
+    }
+
+    /// Shrinks the capacity of the set as much as possible. It will drop
+    /// down as much as possible while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set = HashSet::with_capacity(100);
+    /// set.insert(1);
+    /// set.insert(2);
+    /// assert!(set.capacity() >= 100);
+    /// set.shrink_to_fit();
+    /// assert!(set.capacity() >= 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn shrink_to_fit(&mut self) {
+        self.map.shrink_to_fit();
+    }
+
+    /// Shrinks the capacity of the set with a lower limit. It will drop
+    /// down no lower than the supplied limit while maintaining the internal rules
+    /// and possibly leaving some space in accordance with the resize policy.
+    ///
+    /// Panics if the current capacity is smaller than the supplied
+    /// minimum capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set = HashSet::with_capacity(100);
+    /// set.insert(1);
+    /// set.insert(2);
+    /// assert!(set.capacity() >= 100);
+    /// set.shrink_to(10);
+    /// assert!(set.capacity() >= 10);
+    /// set.shrink_to(0);
+    /// assert!(set.capacity() >= 2);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn shrink_to(&mut self, min_capacity: usize) {
+        self.map.shrink_to(min_capacity);
+    }
+
+    /// Visits the values representing the difference,
+    /// i.e., the values that are in `self` but not in `other`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+    ///
+    /// // Can be seen as `a - b`.
+    /// for x in a.difference(&b) {
+    ///     println!("{}", x); // Print 1
+    /// }
+    ///
+    /// let diff: HashSet<_> = a.difference(&b).collect();
+    /// assert_eq!(diff, [1].iter().collect());
+    ///
+    /// // Note that difference is not symmetric,
+    /// // and `b - a` means something else:
+    /// let diff: HashSet<_> = b.difference(&a).collect();
+    /// assert_eq!(diff, [4].iter().collect());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn difference<'a>(&'a self, other: &'a Self) -> Difference<'a, T, S, A> {
+        Difference {
+            iter: self.iter(),
+            other,
+        }
+    }
+
+    /// Visits the values representing the symmetric difference,
+    /// i.e., the values that are in `self` or in `other` but not in both.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+    ///
+    /// // Print 1, 4 in arbitrary order.
+    /// for x in a.symmetric_difference(&b) {
+    ///     println!("{}", x);
+    /// }
+    ///
+    /// let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
+    /// let diff2: HashSet<_> = b.symmetric_difference(&a).collect();
+    ///
+    /// assert_eq!(diff1, diff2);
+    /// assert_eq!(diff1, [1, 4].iter().collect());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn symmetric_difference<'a>(&'a self, other: &'a Self) -> SymmetricDifference<'a, T, S, A> {
+        SymmetricDifference {
+            iter: self.difference(other).chain(other.difference(self)),
+        }
+    }
+
+    /// Visits the values representing the intersection,
+    /// i.e., the values that are both in `self` and `other`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+    ///
+    /// // Print 2, 3 in arbitrary order.
+    /// for x in a.intersection(&b) {
+    ///     println!("{}", x);
+    /// }
+    ///
+    /// let intersection: HashSet<_> = a.intersection(&b).collect();
+    /// assert_eq!(intersection, [2, 3].iter().collect());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn intersection<'a>(&'a self, other: &'a Self) -> Intersection<'a, T, S, A> {
+        let (smaller, larger) = if self.len() <= other.len() {
+            (self, other)
+        } else {
+            (other, self)
+        };
+        Intersection {
+            iter: smaller.iter(),
+            other: larger,
+        }
+    }
+
+    /// Visits the values representing the union,
+    /// i.e., all the values in `self` or `other`, without duplicates.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();
+    ///
+    /// // Print 1, 2, 3, 4 in arbitrary order.
+    /// for x in a.union(&b) {
+    ///     println!("{}", x);
+    /// }
+    ///
+    /// let union: HashSet<_> = a.union(&b).collect();
+    /// assert_eq!(union, [1, 2, 3, 4].iter().collect());
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, T, S, A> {
+        // We'll iterate one set in full, and only the remaining difference from the other.
+        // Use the smaller set for the difference in order to reduce hash lookups.
+        let (smaller, larger) = if self.len() <= other.len() {
+            (self, other)
+        } else {
+            (other, self)
+        };
+        Union {
+            iter: larger.iter().chain(smaller.difference(larger)),
+        }
+    }
+
+    /// Returns `true` if the set contains a value.
+    ///
+    /// The value may be any borrowed form of the set's value type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the value type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// assert_eq!(set.contains(&1), true);
+    /// assert_eq!(set.contains(&4), false);
+    /// ```
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn contains<Q: ?Sized>(&self, value: &Q) -> bool
+    where
+        Q: Hash + Equivalent<T>,
+    {
+        self.map.contains_key(value)
+    }
+
+    /// Returns a reference to the value in the set, if any, that is equal to the given value.
+    ///
+    /// The value may be any borrowed form of the set's value type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the value type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// assert_eq!(set.get(&2), Some(&2));
+    /// assert_eq!(set.get(&4), None);
+    /// ```
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get<Q: ?Sized>(&self, value: &Q) -> Option<&T>
+    where
+        Q: Hash + Equivalent<T>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.map.get_key_value(value) {
+            Some((k, _)) => Some(k),
+            None => None,
+        }
+    }
+
+    /// Inserts the given `value` into the set if it is not present, then
+    /// returns a reference to the value in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// assert_eq!(set.len(), 3);
+    /// assert_eq!(set.get_or_insert(2), &2);
+    /// assert_eq!(set.get_or_insert(100), &100);
+    /// assert_eq!(set.len(), 4); // 100 was inserted
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_or_insert(&mut self, value: T) -> &T {
+        // Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
+        // `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
+        self.map
+            .raw_entry_mut()
+            .from_key(&value)
+            .or_insert(value, ())
+            .0
+    }
+
+    /// Inserts an owned copy of the given `value` into the set if it is not
+    /// present, then returns a reference to the value in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<String> = ["cat", "dog", "horse"]
+    ///     .iter().map(|&pet| pet.to_owned()).collect();
+    ///
+    /// assert_eq!(set.len(), 3);
+    /// for &pet in &["cat", "dog", "fish"] {
+    ///     let value = set.get_or_insert_owned(pet);
+    ///     assert_eq!(value, pet);
+    /// }
+    /// assert_eq!(set.len(), 4); // a new "fish" was inserted
+    /// ```
+    #[inline]
+    pub fn get_or_insert_owned<Q: ?Sized>(&mut self, value: &Q) -> &T
+    where
+        Q: Hash + Equivalent<T> + ToOwned<Owned = T>,
+    {
+        // Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
+        // `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
+        self.map
+            .raw_entry_mut()
+            .from_key(value)
+            .or_insert_with(|| (value.to_owned(), ()))
+            .0
+    }
+
+    /// Inserts a value computed from `f` into the set if the given `value` is
+    /// not present, then returns a reference to the value in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<String> = ["cat", "dog", "horse"]
+    ///     .iter().map(|&pet| pet.to_owned()).collect();
+    ///
+    /// assert_eq!(set.len(), 3);
+    /// for &pet in &["cat", "dog", "fish"] {
+    ///     let value = set.get_or_insert_with(pet, str::to_owned);
+    ///     assert_eq!(value, pet);
+    /// }
+    /// assert_eq!(set.len(), 4); // a new "fish" was inserted
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get_or_insert_with<Q: ?Sized, F>(&mut self, value: &Q, f: F) -> &T
+    where
+        Q: Hash + Equivalent<T>,
+        F: FnOnce(&Q) -> T,
+    {
+        // Although the raw entry gives us `&mut T`, we only return `&T` to be consistent with
+        // `get`. Key mutation is "raw" because you're not supposed to affect `Eq` or `Hash`.
+        self.map
+            .raw_entry_mut()
+            .from_key(value)
+            .or_insert_with(|| (f(value), ()))
+            .0
+    }
+
+    /// Gets the given value's corresponding entry in the set for in-place manipulation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_set::Entry::*;
+    ///
+    /// let mut singles = HashSet::new();
+    /// let mut dupes = HashSet::new();
+    ///
+    /// for ch in "a short treatise on fungi".chars() {
+    ///     if let Vacant(dupe_entry) = dupes.entry(ch) {
+    ///         // We haven't already seen a duplicate, so
+    ///         // check if we've at least seen it once.
+    ///         match singles.entry(ch) {
+    ///             Vacant(single_entry) => {
+    ///                 // We found a new character for the first time.
+    ///                 single_entry.insert()
+    ///             }
+    ///             Occupied(single_entry) => {
+    ///                 // We've already seen this once, "move" it to dupes.
+    ///                 single_entry.remove();
+    ///                 dupe_entry.insert();
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    ///
+    /// assert!(!singles.contains(&'t') && dupes.contains(&'t'));
+    /// assert!(singles.contains(&'u') && !dupes.contains(&'u'));
+    /// assert!(!singles.contains(&'v') && !dupes.contains(&'v'));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn entry(&mut self, value: T) -> Entry<'_, T, S, A> {
+        match self.map.entry(value) {
+            map::Entry::Occupied(entry) => Entry::Occupied(OccupiedEntry { inner: entry }),
+            map::Entry::Vacant(entry) => Entry::Vacant(VacantEntry { inner: entry }),
+        }
+    }
+
+    /// Returns `true` if `self` has no elements in common with `other`.
+    /// This is equivalent to checking for an empty intersection.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let mut b = HashSet::new();
+    ///
+    /// assert_eq!(a.is_disjoint(&b), true);
+    /// b.insert(4);
+    /// assert_eq!(a.is_disjoint(&b), true);
+    /// b.insert(1);
+    /// assert_eq!(a.is_disjoint(&b), false);
+    /// ```
+    pub fn is_disjoint(&self, other: &Self) -> bool {
+        self.iter().all(|v| !other.contains(v))
+    }
+
+    /// Returns `true` if the set is a subset of another,
+    /// i.e., `other` contains at least all the values in `self`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// let mut set = HashSet::new();
+    ///
+    /// assert_eq!(set.is_subset(&sup), true);
+    /// set.insert(2);
+    /// assert_eq!(set.is_subset(&sup), true);
+    /// set.insert(4);
+    /// assert_eq!(set.is_subset(&sup), false);
+    /// ```
+    pub fn is_subset(&self, other: &Self) -> bool {
+        self.len() <= other.len() && self.iter().all(|v| other.contains(v))
+    }
+
+    /// Returns `true` if the set is a superset of another,
+    /// i.e., `self` contains at least all the values in `other`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let sub: HashSet<_> = [1, 2].iter().cloned().collect();
+    /// let mut set = HashSet::new();
+    ///
+    /// assert_eq!(set.is_superset(&sub), false);
+    ///
+    /// set.insert(0);
+    /// set.insert(1);
+    /// assert_eq!(set.is_superset(&sub), false);
+    ///
+    /// set.insert(2);
+    /// assert_eq!(set.is_superset(&sub), true);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn is_superset(&self, other: &Self) -> bool {
+        other.is_subset(self)
+    }
+
+    /// Adds a value to the set.
+    ///
+    /// If the set did not have this value present, `true` is returned.
+    ///
+    /// If the set did have this value present, `false` is returned.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set = HashSet::new();
+    ///
+    /// assert_eq!(set.insert(2), true);
+    /// assert_eq!(set.insert(2), false);
+    /// assert_eq!(set.len(), 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(&mut self, value: T) -> bool {
+        self.map.insert(value, ()).is_none()
+    }
+
+    /// Insert a value the set without checking if the value already exists in the set.
+    ///
+    /// Returns a reference to the value just inserted.
+    ///
+    /// This operation is safe if a value does not exist in the set.
+    ///
+    /// However, if a value exists in the set already, the behavior is unspecified:
+    /// this operation may panic, loop forever, or any following operation with the set
+    /// may panic, loop forever or return arbitrary result.
+    ///
+    /// That said, this operation (and following operations) are guaranteed to
+    /// not violate memory safety.
+    ///
+    /// This operation is faster than regular insert, because it does not perform
+    /// lookup before insertion.
+    ///
+    /// This operation is useful during initial population of the set.
+    /// For example, when constructing a set from another set, we know
+    /// that values are unique.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert_unique_unchecked(&mut self, value: T) -> &T {
+        self.map.insert_unique_unchecked(value, ()).0
+    }
+
+    /// Adds a value to the set, replacing the existing value, if any, that is equal to the given
+    /// one. Returns the replaced value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set = HashSet::new();
+    /// set.insert(Vec::<i32>::new());
+    ///
+    /// assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
+    /// set.replace(Vec::with_capacity(10));
+    /// assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace(&mut self, value: T) -> Option<T> {
+        match self.map.entry(value) {
+            map::Entry::Occupied(occupied) => Some(occupied.replace_key()),
+            map::Entry::Vacant(vacant) => {
+                vacant.insert(());
+                None
+            }
+        }
+    }
+
+    /// Removes a value from the set. Returns whether the value was
+    /// present in the set.
+    ///
+    /// The value may be any borrowed form of the set's value type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the value type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set = HashSet::new();
+    ///
+    /// set.insert(2);
+    /// assert_eq!(set.remove(&2), true);
+    /// assert_eq!(set.remove(&2), false);
+    /// ```
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool
+    where
+        Q: Hash + Equivalent<T>,
+    {
+        self.map.remove(value).is_some()
+    }
+
+    /// Removes and returns the value in the set, if any, that is equal to the given one.
+    ///
+    /// The value may be any borrowed form of the set's value type, but
+    /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
+    /// the value type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
+    /// assert_eq!(set.take(&2), Some(2));
+    /// assert_eq!(set.take(&2), None);
+    /// ```
+    ///
+    /// [`Eq`]: https://doc.rust-lang.org/std/cmp/trait.Eq.html
+    /// [`Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn take<Q: ?Sized>(&mut self, value: &Q) -> Option<T>
+    where
+        Q: Hash + Equivalent<T>,
+    {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.map.remove_entry(value) {
+            Some((k, _)) => Some(k),
+            None => None,
+        }
+    }
+}
+
+impl<T, S, A: Allocator> HashSet<T, S, A> {
+    /// Returns a reference to the [`RawTable`] used underneath [`HashSet`].
+    /// This function is only available if the `raw` feature of the crate is enabled.
+    ///
+    /// # Note
+    ///
+    /// Calling this function is safe, but using the raw hash table API may require
+    /// unsafe functions or blocks.
+    ///
+    /// `RawTable` API gives the lowest level of control under the set that can be useful
+    /// for extending the HashSet's API, but may lead to *[undefined behavior]*.
+    ///
+    /// [`HashSet`]: struct.HashSet.html
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_table(&self) -> &RawTable<(T, ()), A> {
+        self.map.raw_table()
+    }
+
+    /// Returns a mutable reference to the [`RawTable`] used underneath [`HashSet`].
+    /// This function is only available if the `raw` feature of the crate is enabled.
+    ///
+    /// # Note
+    ///
+    /// Calling this function is safe, but using the raw hash table API may require
+    /// unsafe functions or blocks.
+    ///
+    /// `RawTable` API gives the lowest level of control under the set that can be useful
+    /// for extending the HashSet's API, but may lead to *[undefined behavior]*.
+    ///
+    /// [`HashSet`]: struct.HashSet.html
+    /// [`RawTable`]: crate::raw::RawTable
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[cfg(feature = "raw")]
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn raw_table_mut(&mut self) -> &mut RawTable<(T, ()), A> {
+        self.map.raw_table_mut()
+    }
+}
+
+impl<T, S, A> PartialEq for HashSet<T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn eq(&self, other: &Self) -> bool {
+        if self.len() != other.len() {
+            return false;
+        }
+
+        self.iter().all(|key| other.contains(key))
+    }
+}
+
+impl<T, S, A> Eq for HashSet<T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<T, S, A> fmt::Debug for HashSet<T, S, A>
+where
+    T: fmt::Debug,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_set().entries(self.iter()).finish()
+    }
+}
+
+impl<T, S, A> From<HashMap<T, (), S, A>> for HashSet<T, S, A>
+where
+    A: Allocator,
+{
+    fn from(map: HashMap<T, (), S, A>) -> Self {
+        Self { map }
+    }
+}
+
+impl<T, S, A> FromIterator<T> for HashSet<T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher + Default,
+    A: Default + Allocator,
+{
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
+        let mut set = Self::with_hasher_in(Default::default(), Default::default());
+        set.extend(iter);
+        set
+    }
+}
+
+// The default hasher is used to match the std implementation signature
+#[cfg(feature = "ahash")]
+impl<T, A, const N: usize> From<[T; N]> for HashSet<T, DefaultHashBuilder, A>
+where
+    T: Eq + Hash,
+    A: Default + Allocator,
+{
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let set1 = HashSet::from([1, 2, 3, 4]);
+    /// let set2: HashSet<_> = [1, 2, 3, 4].into();
+    /// assert_eq!(set1, set2);
+    /// ```
+    fn from(arr: [T; N]) -> Self {
+        arr.into_iter().collect()
+    }
+}
+
+impl<T, S, A> Extend<T> for HashSet<T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
+        self.map.extend(iter.into_iter().map(|k| (k, ())));
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_one(&mut self, k: T) {
+        self.map.insert(k, ());
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_reserve(&mut self, additional: usize) {
+        Extend::<(T, ())>::extend_reserve(&mut self.map, additional);
+    }
+}
+
+impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A>
+where
+    T: 'a + Eq + Hash + Copy,
+    S: BuildHasher,
+    A: Allocator,
+{
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
+        self.extend(iter.into_iter().copied());
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_one(&mut self, k: &'a T) {
+        self.map.insert(*k, ());
+    }
+
+    #[inline]
+    #[cfg(feature = "nightly")]
+    fn extend_reserve(&mut self, additional: usize) {
+        Extend::<(T, ())>::extend_reserve(&mut self.map, additional);
+    }
+}
+
+impl<T, S, A> Default for HashSet<T, S, A>
+where
+    S: Default,
+    A: Default + Allocator,
+{
+    /// Creates an empty `HashSet<T, S>` with the `Default` value for the hasher.
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn default() -> Self {
+        Self {
+            map: HashMap::default(),
+        }
+    }
+}
+
+impl<T, S, A> BitOr<&HashSet<T, S, A>> for &HashSet<T, S, A>
+where
+    T: Eq + Hash + Clone,
+    S: BuildHasher + Default,
+    A: Allocator,
+{
+    type Output = HashSet<T, S>;
+
+    /// Returns the union of `self` and `rhs` as a new `HashSet<T, S>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+    /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+    ///
+    /// let set = &a | &b;
+    ///
+    /// let mut i = 0;
+    /// let expected = [1, 2, 3, 4, 5];
+    /// for x in &set {
+    ///     assert!(expected.contains(x));
+    ///     i += 1;
+    /// }
+    /// assert_eq!(i, expected.len());
+    /// ```
+    fn bitor(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S> {
+        self.union(rhs).cloned().collect()
+    }
+}
+
+impl<T, S, A> BitAnd<&HashSet<T, S, A>> for &HashSet<T, S, A>
+where
+    T: Eq + Hash + Clone,
+    S: BuildHasher + Default,
+    A: Allocator,
+{
+    type Output = HashSet<T, S>;
+
+    /// Returns the intersection of `self` and `rhs` as a new `HashSet<T, S>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+    /// let b: HashSet<_> = vec![2, 3, 4].into_iter().collect();
+    ///
+    /// let set = &a & &b;
+    ///
+    /// let mut i = 0;
+    /// let expected = [2, 3];
+    /// for x in &set {
+    ///     assert!(expected.contains(x));
+    ///     i += 1;
+    /// }
+    /// assert_eq!(i, expected.len());
+    /// ```
+    fn bitand(self, rhs: &HashSet<T, S, A>) -> HashSet<T, S> {
+        self.intersection(rhs).cloned().collect()
+    }
+}
+
+impl<T, S> BitXor<&HashSet<T, S>> for &HashSet<T, S>
+where
+    T: Eq + Hash + Clone,
+    S: BuildHasher + Default,
+{
+    type Output = HashSet<T, S>;
+
+    /// Returns the symmetric difference of `self` and `rhs` as a new `HashSet<T, S>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+    /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+    ///
+    /// let set = &a ^ &b;
+    ///
+    /// let mut i = 0;
+    /// let expected = [1, 2, 4, 5];
+    /// for x in &set {
+    ///     assert!(expected.contains(x));
+    ///     i += 1;
+    /// }
+    /// assert_eq!(i, expected.len());
+    /// ```
+    fn bitxor(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+        self.symmetric_difference(rhs).cloned().collect()
+    }
+}
+
+impl<T, S> Sub<&HashSet<T, S>> for &HashSet<T, S>
+where
+    T: Eq + Hash + Clone,
+    S: BuildHasher + Default,
+{
+    type Output = HashSet<T, S>;
+
+    /// Returns the difference of `self` and `rhs` as a new `HashSet<T, S>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let a: HashSet<_> = vec![1, 2, 3].into_iter().collect();
+    /// let b: HashSet<_> = vec![3, 4, 5].into_iter().collect();
+    ///
+    /// let set = &a - &b;
+    ///
+    /// let mut i = 0;
+    /// let expected = [1, 2];
+    /// for x in &set {
+    ///     assert!(expected.contains(x));
+    ///     i += 1;
+    /// }
+    /// assert_eq!(i, expected.len());
+    /// ```
+    fn sub(self, rhs: &HashSet<T, S>) -> HashSet<T, S> {
+        self.difference(rhs).cloned().collect()
+    }
+}
+
+/// An iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`iter`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`iter`]: struct.HashSet.html#method.iter
+pub struct Iter<'a, K> {
+    iter: Keys<'a, K, ()>,
+}
+
+/// An owning iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`into_iter`] method on [`HashSet`]
+/// (provided by the `IntoIterator` trait). See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`into_iter`]: struct.HashSet.html#method.into_iter
+pub struct IntoIter<K, A: Allocator = Global> {
+    iter: map::IntoIter<K, (), A>,
+}
+
+/// A draining iterator over the items of a `HashSet`.
+///
+/// This `struct` is created by the [`drain`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`drain`]: struct.HashSet.html#method.drain
+pub struct Drain<'a, K, A: Allocator = Global> {
+    iter: map::Drain<'a, K, (), A>,
+}
+
+/// A draining iterator over entries of a `HashSet` which don't satisfy the predicate `f`.
+///
+/// This `struct` is created by the [`extract_if`] method on [`HashSet`]. See its
+/// documentation for more.
+///
+/// [`extract_if`]: struct.HashSet.html#method.extract_if
+/// [`HashSet`]: struct.HashSet.html
+#[must_use = "Iterators are lazy unless consumed"]
+pub struct ExtractIf<'a, K, F, A: Allocator = Global>
+where
+    F: FnMut(&K) -> bool,
+{
+    f: F,
+    inner: ExtractIfInner<'a, K, (), A>,
+}
+
+/// A lazy iterator producing elements in the intersection of `HashSet`s.
+///
+/// This `struct` is created by the [`intersection`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`intersection`]: struct.HashSet.html#method.intersection
+pub struct Intersection<'a, T, S, A: Allocator = Global> {
+    // iterator of the first set
+    iter: Iter<'a, T>,
+    // the second set
+    other: &'a HashSet<T, S, A>,
+}
+
+/// A lazy iterator producing elements in the difference of `HashSet`s.
+///
+/// This `struct` is created by the [`difference`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`difference`]: struct.HashSet.html#method.difference
+pub struct Difference<'a, T, S, A: Allocator = Global> {
+    // iterator of the first set
+    iter: Iter<'a, T>,
+    // the second set
+    other: &'a HashSet<T, S, A>,
+}
+
+/// A lazy iterator producing elements in the symmetric difference of `HashSet`s.
+///
+/// This `struct` is created by the [`symmetric_difference`] method on
+/// [`HashSet`]. See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`symmetric_difference`]: struct.HashSet.html#method.symmetric_difference
+pub struct SymmetricDifference<'a, T, S, A: Allocator = Global> {
+    iter: Chain<Difference<'a, T, S, A>, Difference<'a, T, S, A>>,
+}
+
+/// A lazy iterator producing elements in the union of `HashSet`s.
+///
+/// This `struct` is created by the [`union`] method on [`HashSet`].
+/// See its documentation for more.
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`union`]: struct.HashSet.html#method.union
+pub struct Union<'a, T, S, A: Allocator = Global> {
+    iter: Chain<Iter<'a, T>, Difference<'a, T, S, A>>,
+}
+
+impl<'a, T, S, A: Allocator> IntoIterator for &'a HashSet<T, S, A> {
+    type Item = &'a T;
+    type IntoIter = Iter<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> Iter<'a, T> {
+        self.iter()
+    }
+}
+
+impl<T, S, A: Allocator> IntoIterator for HashSet<T, S, A> {
+    type Item = T;
+    type IntoIter = IntoIter<T, A>;
+
+    /// Creates a consuming iterator, that is, one that moves each value out
+    /// of the set in arbitrary order. The set cannot be used after calling
+    /// this.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// let mut set = HashSet::new();
+    /// set.insert("a".to_string());
+    /// set.insert("b".to_string());
+    ///
+    /// // Not possible to collect to a Vec<String> with a regular `.iter()`.
+    /// let v: Vec<String> = set.into_iter().collect();
+    ///
+    /// // Will print in an arbitrary order.
+    /// for x in &v {
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_iter(self) -> IntoIter<T, A> {
+        IntoIter {
+            iter: self.map.into_iter(),
+        }
+    }
+}
+
+impl<K> Clone for Iter<'_, K> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Iter {
+            iter: self.iter.clone(),
+        }
+    }
+}
+impl<'a, K> Iterator for Iter<'a, K> {
+    type Item = &'a K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a K> {
+        self.iter.next()
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+impl<'a, K> ExactSizeIterator for Iter<'a, K> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
+impl<K> FusedIterator for Iter<'_, K> {}
+
+impl<K: fmt::Debug> fmt::Debug for Iter<'_, K> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl<K, A: Allocator> Iterator for IntoIter<K, A> {
+    type Item = K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<K> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.iter.next() {
+            Some((k, _)) => Some(k),
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+impl<K, A: Allocator> ExactSizeIterator for IntoIter<K, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
+impl<K, A: Allocator> FusedIterator for IntoIter<K, A> {}
+
+impl<K: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<K, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let entries_iter = self.iter.iter().map(|(k, _)| k);
+        f.debug_list().entries(entries_iter).finish()
+    }
+}
+
+impl<K, A: Allocator> Iterator for Drain<'_, K, A> {
+    type Item = K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<K> {
+        // Avoid `Option::map` because it bloats LLVM IR.
+        match self.iter.next() {
+            Some((k, _)) => Some(k),
+            None => None,
+        }
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+impl<K, A: Allocator> ExactSizeIterator for Drain<'_, K, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
+impl<K, A: Allocator> FusedIterator for Drain<'_, K, A> {}
+
+impl<K: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, K, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let entries_iter = self.iter.iter().map(|(k, _)| k);
+        f.debug_list().entries(entries_iter).finish()
+    }
+}
+
+impl<K, F, A: Allocator> Iterator for ExtractIf<'_, K, F, A>
+where
+    F: FnMut(&K) -> bool,
+{
+    type Item = K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<Self::Item> {
+        let f = &mut self.f;
+        let (k, _) = self.inner.next(&mut |k, _| f(k))?;
+        Some(k)
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (0, self.inner.iter.size_hint().1)
+    }
+}
+
+impl<K, F, A: Allocator> FusedIterator for ExtractIf<'_, K, F, A> where F: FnMut(&K) -> bool {}
+
+impl<T, S, A: Allocator> Clone for Intersection<'_, T, S, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Intersection {
+            iter: self.iter.clone(),
+            ..*self
+        }
+    }
+}
+
+impl<'a, T, S, A> Iterator for Intersection<'a, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a T> {
+        loop {
+            let elt = self.iter.next()?;
+            if self.other.contains(elt) {
+                return Some(elt);
+            }
+        }
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (_, upper) = self.iter.size_hint();
+        (0, upper)
+    }
+}
+
+impl<T, S, A> fmt::Debug for Intersection<'_, T, S, A>
+where
+    T: fmt::Debug + Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl<T, S, A> FusedIterator for Intersection<'_, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<T, S, A: Allocator> Clone for Difference<'_, T, S, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Difference {
+            iter: self.iter.clone(),
+            ..*self
+        }
+    }
+}
+
+impl<'a, T, S, A> Iterator for Difference<'a, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a T> {
+        loop {
+            let elt = self.iter.next()?;
+            if !self.other.contains(elt) {
+                return Some(elt);
+            }
+        }
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let (_, upper) = self.iter.size_hint();
+        (0, upper)
+    }
+}
+
+impl<T, S, A> FusedIterator for Difference<'_, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<T, S, A> fmt::Debug for Difference<'_, T, S, A>
+where
+    T: fmt::Debug + Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl<T, S, A: Allocator> Clone for SymmetricDifference<'_, T, S, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        SymmetricDifference {
+            iter: self.iter.clone(),
+        }
+    }
+}
+
+impl<'a, T, S, A> Iterator for SymmetricDifference<'a, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a T> {
+        self.iter.next()
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<T, S, A> FusedIterator for SymmetricDifference<'_, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<T, S, A> fmt::Debug for SymmetricDifference<'_, T, S, A>
+where
+    T: fmt::Debug + Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl<T, S, A: Allocator> Clone for Union<'_, T, S, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Union {
+            iter: self.iter.clone(),
+        }
+    }
+}
+
+impl<T, S, A> FusedIterator for Union<'_, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+}
+
+impl<T, S, A> fmt::Debug for Union<'_, T, S, A>
+where
+    T: fmt::Debug + Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+impl<'a, T, S, A> Iterator for Union<'a, T, S, A>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+    A: Allocator,
+{
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn next(&mut self) -> Option<&'a T> {
+        self.iter.next()
+    }
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+/// A view into a single entry in a set, which may either be vacant or occupied.
+///
+/// This `enum` is constructed from the [`entry`] method on [`HashSet`].
+///
+/// [`HashSet`]: struct.HashSet.html
+/// [`entry`]: struct.HashSet.html#method.entry
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_set::{Entry, HashSet, OccupiedEntry};
+///
+/// let mut set = HashSet::new();
+/// set.extend(["a", "b", "c"]);
+/// assert_eq!(set.len(), 3);
+///
+/// // Existing value (insert)
+/// let entry: Entry<_, _> = set.entry("a");
+/// let _raw_o: OccupiedEntry<_, _> = entry.insert();
+/// assert_eq!(set.len(), 3);
+/// // Nonexistent value (insert)
+/// set.entry("d").insert();
+///
+/// // Existing value (or_insert)
+/// set.entry("b").or_insert();
+/// // Nonexistent value (or_insert)
+/// set.entry("e").or_insert();
+///
+/// println!("Our HashSet: {:?}", set);
+///
+/// let mut vec: Vec<_> = set.iter().copied().collect();
+/// // The `Iter` iterator produces items in arbitrary order, so the
+/// // items must be sorted to test them against a sorted array.
+/// vec.sort_unstable();
+/// assert_eq!(vec, ["a", "b", "c", "d", "e"]);
+/// ```
+pub enum Entry<'a, T, S, A = Global>
+where
+    A: Allocator,
+{
+    /// An occupied entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_set::{Entry, HashSet};
+    /// let mut set: HashSet<_> = ["a", "b"].into();
+    ///
+    /// match set.entry("a") {
+    ///     Entry::Vacant(_) => unreachable!(),
+    ///     Entry::Occupied(_) => { }
+    /// }
+    /// ```
+    Occupied(OccupiedEntry<'a, T, S, A>),
+
+    /// A vacant entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_set::{Entry, HashSet};
+    /// let mut set: HashSet<&str> = HashSet::new();
+    ///
+    /// match set.entry("a") {
+    ///     Entry::Occupied(_) => unreachable!(),
+    ///     Entry::Vacant(_) => { }
+    /// }
+    /// ```
+    Vacant(VacantEntry<'a, T, S, A>),
+}
+
+impl<T: fmt::Debug, S, A: Allocator> fmt::Debug for Entry<'_, T, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            Entry::Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(),
+            Entry::Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(),
+        }
+    }
+}
+
+/// A view into an occupied entry in a `HashSet`.
+/// It is part of the [`Entry`] enum.
+///
+/// [`Entry`]: enum.Entry.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_set::{Entry, HashSet, OccupiedEntry};
+///
+/// let mut set = HashSet::new();
+/// set.extend(["a", "b", "c"]);
+///
+/// let _entry_o: OccupiedEntry<_, _> = set.entry("a").insert();
+/// assert_eq!(set.len(), 3);
+///
+/// // Existing key
+/// match set.entry("a") {
+///     Entry::Vacant(_) => unreachable!(),
+///     Entry::Occupied(view) => {
+///         assert_eq!(view.get(), &"a");
+///     }
+/// }
+///
+/// assert_eq!(set.len(), 3);
+///
+/// // Existing key (take)
+/// match set.entry("c") {
+///     Entry::Vacant(_) => unreachable!(),
+///     Entry::Occupied(view) => {
+///         assert_eq!(view.remove(), "c");
+///     }
+/// }
+/// assert_eq!(set.get(&"c"), None);
+/// assert_eq!(set.len(), 2);
+/// ```
+pub struct OccupiedEntry<'a, T, S, A: Allocator = Global> {
+    inner: map::OccupiedEntry<'a, T, (), S, A>,
+}
+
+impl<T: fmt::Debug, S, A: Allocator> fmt::Debug for OccupiedEntry<'_, T, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OccupiedEntry")
+            .field("value", self.get())
+            .finish()
+    }
+}
+
+/// A view into a vacant entry in a `HashSet`.
+/// It is part of the [`Entry`] enum.
+///
+/// [`Entry`]: enum.Entry.html
+///
+/// # Examples
+///
+/// ```
+/// use hashbrown::hash_set::{Entry, HashSet, VacantEntry};
+///
+/// let mut set = HashSet::<&str>::new();
+///
+/// let entry_v: VacantEntry<_, _> = match set.entry("a") {
+///     Entry::Vacant(view) => view,
+///     Entry::Occupied(_) => unreachable!(),
+/// };
+/// entry_v.insert();
+/// assert!(set.contains("a") && set.len() == 1);
+///
+/// // Nonexistent key (insert)
+/// match set.entry("b") {
+///     Entry::Vacant(view) => view.insert(),
+///     Entry::Occupied(_) => unreachable!(),
+/// }
+/// assert!(set.contains("b") && set.len() == 2);
+/// ```
+pub struct VacantEntry<'a, T, S, A: Allocator = Global> {
+    inner: map::VacantEntry<'a, T, (), S, A>,
+}
+
+impl<T: fmt::Debug, S, A: Allocator> fmt::Debug for VacantEntry<'_, T, S, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VacantEntry").field(self.get()).finish()
+    }
+}
+
+impl<'a, T, S, A: Allocator> Entry<'a, T, S, A> {
+    /// Sets the value of the entry, and returns an OccupiedEntry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    /// let entry = set.entry("horseyland").insert();
+    ///
+    /// assert_eq!(entry.get(), &"horseyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self) -> OccupiedEntry<'a, T, S, A>
+    where
+        T: Hash,
+        S: BuildHasher,
+    {
+        match self {
+            Entry::Occupied(entry) => entry,
+            Entry::Vacant(entry) => entry.insert_entry(),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting if it was vacant.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    ///
+    /// // nonexistent key
+    /// set.entry("poneyland").or_insert();
+    /// assert!(set.contains("poneyland"));
+    ///
+    /// // existing key
+    /// set.entry("poneyland").or_insert();
+    /// assert!(set.contains("poneyland"));
+    /// assert_eq!(set.len(), 1);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn or_insert(self)
+    where
+        T: Hash,
+        S: BuildHasher,
+    {
+        if let Entry::Vacant(entry) = self {
+            entry.insert();
+        }
+    }
+
+    /// Returns a reference to this entry's value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    /// set.entry("poneyland").or_insert();
+    /// // existing key
+    /// assert_eq!(set.entry("poneyland").get(), &"poneyland");
+    /// // nonexistent key
+    /// assert_eq!(set.entry("horseland").get(), &"horseland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &T {
+        match *self {
+            Entry::Occupied(ref entry) => entry.get(),
+            Entry::Vacant(ref entry) => entry.get(),
+        }
+    }
+}
+
+impl<T, S, A: Allocator> OccupiedEntry<'_, T, S, A> {
+    /// Gets a reference to the value in the entry.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_set::{Entry, HashSet};
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    /// set.entry("poneyland").or_insert();
+    ///
+    /// match set.entry("poneyland") {
+    ///     Entry::Vacant(_) => panic!(),
+    ///     Entry::Occupied(entry) => assert_eq!(entry.get(), &"poneyland"),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &T {
+        self.inner.key()
+    }
+
+    /// Takes the value out of the entry, and returns it.
+    /// Keeps the allocated memory for reuse.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_set::Entry;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    /// // The set is empty
+    /// assert!(set.is_empty() && set.capacity() == 0);
+    ///
+    /// set.entry("poneyland").or_insert();
+    /// let capacity_before_remove = set.capacity();
+    ///
+    /// if let Entry::Occupied(o) = set.entry("poneyland") {
+    ///     assert_eq!(o.remove(), "poneyland");
+    /// }
+    ///
+    /// assert_eq!(set.contains("poneyland"), false);
+    /// // Now set hold none elements but capacity is equal to the old one
+    /// assert!(set.len() == 0 && set.capacity() == capacity_before_remove);
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn remove(self) -> T {
+        self.inner.remove_entry().0
+    }
+
+    /// Replaces the entry, returning the old value. The new value in the hash map will be
+    /// the value used to create this entry.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if this OccupiedEntry was created through [`Entry::insert`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    ///  use hashbrown::hash_set::{Entry, HashSet};
+    ///  use std::rc::Rc;
+    ///
+    ///  let mut set: HashSet<Rc<String>> = HashSet::new();
+    ///  let key_one = Rc::new("Stringthing".to_string());
+    ///  let key_two = Rc::new("Stringthing".to_string());
+    ///
+    ///  set.insert(key_one.clone());
+    ///  assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);
+    ///
+    ///  match set.entry(key_two.clone()) {
+    ///      Entry::Occupied(entry) => {
+    ///          let old_key: Rc<String> = entry.replace();
+    ///          assert!(Rc::ptr_eq(&key_one, &old_key));
+    ///      }
+    ///      Entry::Vacant(_) => panic!(),
+    ///  }
+    ///
+    ///  assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);
+    ///  assert!(set.contains(&"Stringthing".to_owned()));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn replace(self) -> T {
+        self.inner.replace_key()
+    }
+}
+
+impl<'a, T, S, A: Allocator> VacantEntry<'a, T, S, A> {
+    /// Gets a reference to the value that would be used when inserting
+    /// through the `VacantEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    /// assert_eq!(set.entry("poneyland").get(), &"poneyland");
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn get(&self) -> &T {
+        self.inner.key()
+    }
+
+    /// Take ownership of the value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::hash_set::{Entry, HashSet};
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    ///
+    /// match set.entry("poneyland") {
+    ///     Entry::Occupied(_) => panic!(),
+    ///     Entry::Vacant(v) => assert_eq!(v.into_value(), "poneyland"),
+    /// }
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_value(self) -> T {
+        self.inner.into_key()
+    }
+
+    /// Sets the value of the entry with the VacantEntry's value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use hashbrown::HashSet;
+    /// use hashbrown::hash_set::Entry;
+    ///
+    /// let mut set: HashSet<&str> = HashSet::new();
+    ///
+    /// if let Entry::Vacant(o) = set.entry("poneyland") {
+    ///     o.insert();
+    /// }
+    /// assert!(set.contains("poneyland"));
+    /// ```
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn insert(self)
+    where
+        T: Hash,
+        S: BuildHasher,
+    {
+        self.inner.insert(());
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn insert_entry(self) -> OccupiedEntry<'a, T, S, A>
+    where
+        T: Hash,
+        S: BuildHasher,
+    {
+        OccupiedEntry {
+            inner: self.inner.insert_entry(()),
+        }
+    }
+}
+
+#[allow(dead_code)]
+fn assert_covariance() {
+    fn set<'new>(v: HashSet<&'static str>) -> HashSet<&'new str> {
+        v
+    }
+    fn iter<'a, 'new>(v: Iter<'a, &'static str>) -> Iter<'a, &'new str> {
+        v
+    }
+    fn into_iter<'new, A: Allocator>(v: IntoIter<&'static str, A>) -> IntoIter<&'new str, A> {
+        v
+    }
+    fn difference<'a, 'new, A: Allocator>(
+        v: Difference<'a, &'static str, DefaultHashBuilder, A>,
+    ) -> Difference<'a, &'new str, DefaultHashBuilder, A> {
+        v
+    }
+    fn symmetric_difference<'a, 'new, A: Allocator>(
+        v: SymmetricDifference<'a, &'static str, DefaultHashBuilder, A>,
+    ) -> SymmetricDifference<'a, &'new str, DefaultHashBuilder, A> {
+        v
+    }
+    fn intersection<'a, 'new, A: Allocator>(
+        v: Intersection<'a, &'static str, DefaultHashBuilder, A>,
+    ) -> Intersection<'a, &'new str, DefaultHashBuilder, A> {
+        v
+    }
+    fn union<'a, 'new, A: Allocator>(
+        v: Union<'a, &'static str, DefaultHashBuilder, A>,
+    ) -> Union<'a, &'new str, DefaultHashBuilder, A> {
+        v
+    }
+    fn drain<'new, A: Allocator>(d: Drain<'static, &'static str, A>) -> Drain<'new, &'new str, A> {
+        d
+    }
+}
+
+#[cfg(test)]
+mod test_set {
+    use super::super::map::DefaultHashBuilder;
+    use super::HashSet;
+    use std::vec::Vec;
+
+    #[test]
+    fn test_zero_capacities() {
+        type HS = HashSet<i32>;
+
+        let s = HS::new();
+        assert_eq!(s.capacity(), 0);
+
+        let s = HS::default();
+        assert_eq!(s.capacity(), 0);
+
+        let s = HS::with_hasher(DefaultHashBuilder::default());
+        assert_eq!(s.capacity(), 0);
+
+        let s = HS::with_capacity(0);
+        assert_eq!(s.capacity(), 0);
+
+        let s = HS::with_capacity_and_hasher(0, DefaultHashBuilder::default());
+        assert_eq!(s.capacity(), 0);
+
+        let mut s = HS::new();
+        s.insert(1);
+        s.insert(2);
+        s.remove(&1);
+        s.remove(&2);
+        s.shrink_to_fit();
+        assert_eq!(s.capacity(), 0);
+
+        let mut s = HS::new();
+        s.reserve(0);
+        assert_eq!(s.capacity(), 0);
+    }
+
+    #[test]
+    fn test_disjoint() {
+        let mut xs = HashSet::new();
+        let mut ys = HashSet::new();
+        assert!(xs.is_disjoint(&ys));
+        assert!(ys.is_disjoint(&xs));
+        assert!(xs.insert(5));
+        assert!(ys.insert(11));
+        assert!(xs.is_disjoint(&ys));
+        assert!(ys.is_disjoint(&xs));
+        assert!(xs.insert(7));
+        assert!(xs.insert(19));
+        assert!(xs.insert(4));
+        assert!(ys.insert(2));
+        assert!(ys.insert(-11));
+        assert!(xs.is_disjoint(&ys));
+        assert!(ys.is_disjoint(&xs));
+        assert!(ys.insert(7));
+        assert!(!xs.is_disjoint(&ys));
+        assert!(!ys.is_disjoint(&xs));
+    }
+
+    #[test]
+    fn test_subset_and_superset() {
+        let mut a = HashSet::new();
+        assert!(a.insert(0));
+        assert!(a.insert(5));
+        assert!(a.insert(11));
+        assert!(a.insert(7));
+
+        let mut b = HashSet::new();
+        assert!(b.insert(0));
+        assert!(b.insert(7));
+        assert!(b.insert(19));
+        assert!(b.insert(250));
+        assert!(b.insert(11));
+        assert!(b.insert(200));
+
+        assert!(!a.is_subset(&b));
+        assert!(!a.is_superset(&b));
+        assert!(!b.is_subset(&a));
+        assert!(!b.is_superset(&a));
+
+        assert!(b.insert(5));
+
+        assert!(a.is_subset(&b));
+        assert!(!a.is_superset(&b));
+        assert!(!b.is_subset(&a));
+        assert!(b.is_superset(&a));
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut a = HashSet::new();
+        for i in 0..32 {
+            assert!(a.insert(i));
+        }
+        let mut observed: u32 = 0;
+        for k in &a {
+            observed |= 1 << *k;
+        }
+        assert_eq!(observed, 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_intersection() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(11));
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(77));
+        assert!(a.insert(103));
+        assert!(a.insert(5));
+        assert!(a.insert(-5));
+
+        assert!(b.insert(2));
+        assert!(b.insert(11));
+        assert!(b.insert(77));
+        assert!(b.insert(-9));
+        assert!(b.insert(-42));
+        assert!(b.insert(5));
+        assert!(b.insert(3));
+
+        let mut i = 0;
+        let expected = [3, 5, 11, 77];
+        for x in a.intersection(&b) {
+            assert!(expected.contains(x));
+            i += 1;
+        }
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+
+        let mut i = 0;
+        let expected = [1, 5, 11];
+        for x in a.difference(&b) {
+            assert!(expected.contains(x));
+            i += 1;
+        }
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_symmetric_difference() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(3));
+        assert!(b.insert(9));
+        assert!(b.insert(14));
+        assert!(b.insert(22));
+
+        let mut i = 0;
+        let expected = [-2, 1, 5, 11, 14, 22];
+        for x in a.symmetric_difference(&b) {
+            assert!(expected.contains(x));
+            i += 1;
+        }
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_union() {
+        let mut a = HashSet::new();
+        let mut b = HashSet::new();
+
+        assert!(a.insert(1));
+        assert!(a.insert(3));
+        assert!(a.insert(5));
+        assert!(a.insert(9));
+        assert!(a.insert(11));
+        assert!(a.insert(16));
+        assert!(a.insert(19));
+        assert!(a.insert(24));
+
+        assert!(b.insert(-2));
+        assert!(b.insert(1));
+        assert!(b.insert(5));
+        assert!(b.insert(9));
+        assert!(b.insert(13));
+        assert!(b.insert(19));
+
+        let mut i = 0;
+        let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
+        for x in a.union(&b) {
+            assert!(expected.contains(x));
+            i += 1;
+        }
+        assert_eq!(i, expected.len());
+    }
+
+    #[test]
+    fn test_from_map() {
+        let mut a = crate::HashMap::new();
+        a.insert(1, ());
+        a.insert(2, ());
+        a.insert(3, ());
+        a.insert(4, ());
+
+        let a: HashSet<_> = a.into();
+
+        assert_eq!(a.len(), 4);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [1, 2, 2, 3, 4, 5, 6, 7, 8, 9];
+
+        let set: HashSet<_> = xs.iter().copied().collect();
+
+        for x in &xs {
+            assert!(set.contains(x));
+        }
+
+        assert_eq!(set.iter().len(), xs.len() - 1);
+    }
+
+    #[test]
+    fn test_move_iter() {
+        let hs = {
+            let mut hs = HashSet::new();
+
+            hs.insert('a');
+            hs.insert('b');
+
+            hs
+        };
+
+        let v = hs.into_iter().collect::<Vec<char>>();
+        assert!(v == ['a', 'b'] || v == ['b', 'a']);
+    }
+
+    #[test]
+    fn test_eq() {
+        // These constants once happened to expose a bug in insert().
+        // I'm keeping them around to prevent a regression.
+        let mut s1 = HashSet::new();
+
+        s1.insert(1);
+        s1.insert(2);
+        s1.insert(3);
+
+        let mut s2 = HashSet::new();
+
+        s2.insert(1);
+        s2.insert(2);
+
+        assert!(s1 != s2);
+
+        s2.insert(3);
+
+        assert_eq!(s1, s2);
+    }
+
+    #[test]
+    fn test_show() {
+        let mut set = HashSet::new();
+        let empty = HashSet::<i32>::new();
+
+        set.insert(1);
+        set.insert(2);
+
+        let set_str = format!("{set:?}");
+
+        assert!(set_str == "{1, 2}" || set_str == "{2, 1}");
+        assert_eq!(format!("{empty:?}"), "{}");
+    }
+
+    #[test]
+    fn test_trivial_drain() {
+        let mut s = HashSet::<i32>::new();
+        for _ in s.drain() {}
+        assert!(s.is_empty());
+        drop(s);
+
+        let mut s = HashSet::<i32>::new();
+        drop(s.drain());
+        assert!(s.is_empty());
+    }
+
+    #[test]
+    fn test_drain() {
+        let mut s: HashSet<_> = (1..100).collect();
+
+        // try this a bunch of times to make sure we don't screw up internal state.
+        for _ in 0..20 {
+            assert_eq!(s.len(), 99);
+
+            {
+                let mut last_i = 0;
+                let mut d = s.drain();
+                for (i, x) in d.by_ref().take(50).enumerate() {
+                    last_i = i;
+                    assert!(x != 0);
+                }
+                assert_eq!(last_i, 49);
+            }
+
+            for _ in &s {
+                panic!("s should be empty!");
+            }
+
+            // reset to try again.
+            s.extend(1..100);
+        }
+    }
+
+    #[test]
+    fn test_replace() {
+        use core::hash;
+
+        #[derive(Debug)]
+        struct Foo(&'static str, i32);
+
+        impl PartialEq for Foo {
+            fn eq(&self, other: &Self) -> bool {
+                self.0 == other.0
+            }
+        }
+
+        impl Eq for Foo {}
+
+        impl hash::Hash for Foo {
+            fn hash<H: hash::Hasher>(&self, h: &mut H) {
+                self.0.hash(h);
+            }
+        }
+
+        let mut s = HashSet::new();
+        assert_eq!(s.replace(Foo("a", 1)), None);
+        assert_eq!(s.len(), 1);
+        assert_eq!(s.replace(Foo("a", 2)), Some(Foo("a", 1)));
+        assert_eq!(s.len(), 1);
+
+        let mut it = s.iter();
+        assert_eq!(it.next(), Some(&Foo("a", 2)));
+        assert_eq!(it.next(), None);
+    }
+
+    #[test]
+    #[allow(clippy::needless_borrow)]
+    fn test_extend_ref() {
+        let mut a = HashSet::new();
+        a.insert(1);
+
+        a.extend([2, 3, 4]);
+
+        assert_eq!(a.len(), 4);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+
+        let mut b = HashSet::new();
+        b.insert(5);
+        b.insert(6);
+
+        a.extend(&b);
+
+        assert_eq!(a.len(), 6);
+        assert!(a.contains(&1));
+        assert!(a.contains(&2));
+        assert!(a.contains(&3));
+        assert!(a.contains(&4));
+        assert!(a.contains(&5));
+        assert!(a.contains(&6));
+    }
+
+    #[test]
+    fn test_retain() {
+        let xs = [1, 2, 3, 4, 5, 6];
+        let mut set: HashSet<i32> = xs.iter().copied().collect();
+        set.retain(|&k| k % 2 == 0);
+        assert_eq!(set.len(), 3);
+        assert!(set.contains(&2));
+        assert!(set.contains(&4));
+        assert!(set.contains(&6));
+    }
+
+    #[test]
+    fn test_extract_if() {
+        {
+            let mut set: HashSet<i32> = (0..8).collect();
+            let drained = set.extract_if(|&k| k % 2 == 0);
+            let mut out = drained.collect::<Vec<_>>();
+            out.sort_unstable();
+            assert_eq!(vec![0, 2, 4, 6], out);
+            assert_eq!(set.len(), 4);
+        }
+        {
+            let mut set: HashSet<i32> = (0..8).collect();
+            set.extract_if(|&k| k % 2 == 0).for_each(drop);
+            assert_eq!(set.len(), 4, "Removes non-matching items on drop");
+        }
+    }
+
+    #[test]
+    fn test_const_with_hasher() {
+        use core::hash::BuildHasher;
+        use std::collections::hash_map::DefaultHasher;
+
+        #[derive(Clone)]
+        struct MyHasher;
+        impl BuildHasher for MyHasher {
+            type Hasher = DefaultHasher;
+
+            fn build_hasher(&self) -> DefaultHasher {
+                DefaultHasher::new()
+            }
+        }
+
+        const EMPTY_SET: HashSet<u32, MyHasher> = HashSet::with_hasher(MyHasher);
+
+        let mut set = EMPTY_SET;
+        set.insert(19);
+        assert!(set.contains(&19));
+    }
+
+    #[test]
+    fn rehash_in_place() {
+        let mut set = HashSet::new();
+
+        for i in 0..224 {
+            set.insert(i);
+        }
+
+        assert_eq!(
+            set.capacity(),
+            224,
+            "The set must be at or close to capacity to trigger a re hashing"
+        );
+
+        for i in 100..1400 {
+            set.remove(&(i - 100));
+            set.insert(i);
+        }
+    }
+
+    #[test]
+    fn collect() {
+        // At the time of writing, this hits the ZST case in from_base_index
+        // (and without the `map`, it does not).
+        let mut _set: HashSet<_> = (0..3).map(|_| ()).collect();
+    }
+}