Merging upstream version 1.72.1+dfsg1.

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

16 files changed, 1766 insertions, 513 deletions

diff --git a/vendor/hashbrown/src/external_trait_impls/mod.rs b/vendor/hashbrown/src/external_trait_impls/mod.rs
index ef497836c..01d386b04 100644
--- a/vendor/hashbrown/src/external_trait_impls/mod.rs
+++ b/vendor/hashbrown/src/external_trait_impls/mod.rs
@@ -1,4 +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/map.rs b/vendor/hashbrown/src/external_trait_impls/rayon/map.rs
index 14d91c220..1124bfd32 100644
--- a/vendor/hashbrown/src/external_trait_impls/rayon/map.rs
+++ b/vendor/hashbrown/src/external_trait_impls/rayon/map.rs
@@ -561,10 +561,7 @@ mod test_par_map {
             assert_eq!(value.load(Ordering::Relaxed), 100);
 
             // retain only half
-            let _v: Vec<_> = hm
-                .into_par_iter()
-                .filter(|&(ref key, _)| key.k < 50)
-                .collect();
+            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);
@@ -611,7 +608,7 @@ mod test_par_map {
             assert_eq!(value.load(Ordering::Relaxed), 100);
 
             // retain only half
-            let _v: Vec<_> = hm.drain().filter(|&(ref key, _)| key.k < 50).collect();
+            let _v: Vec<_> = hm.drain().filter(|(key, _)| key.k < 50).collect();
             assert!(hm.is_empty());
 
             assert_eq!(key.load(Ordering::Relaxed), 50);
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 000000000..fae7f7676
--- /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 000000000..c8a69cf4f
--- /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 000000000..2bde6a065
--- /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/lib.rs b/vendor/hashbrown/src/lib.rs
index e43165dd6..013a9ddd9 100644
--- a/vendor/hashbrown/src/lib.rs
+++ b/vendor/hashbrown/src/lib.rs
@@ -20,9 +20,8 @@
         extend_one,
         allocator_api,
         slice_ptr_get,
-        nonnull_slice_from_raw_parts,
         maybe_uninit_array_assume_init,
-        build_hasher_simple_hash_one
+        strict_provenance
     )
 )]
 #![allow(
@@ -37,6 +36,7 @@
 )]
 #![warn(missing_docs)]
 #![warn(rust_2018_idioms)]
+#![cfg_attr(feature = "nightly", warn(fuzzy_provenance_casts))]
 
 #[cfg(test)]
 #[macro_use]
@@ -163,21 +163,3 @@ pub enum TryReserveError {
         layout: alloc::alloc::Layout,
     },
 }
-
-/// Wrapper around `Bump` which allows it to be used as an allocator for
-/// `HashMap`, `HashSet` and `RawTable`.
-///
-/// `Bump` can be used directly without this wrapper on nightly if you enable
-/// the `allocator-api` feature of the `bumpalo` crate.
-#[cfg(feature = "bumpalo")]
-#[derive(Clone, Copy, Debug)]
-pub struct BumpWrapper<'a>(pub &'a bumpalo::Bump);
-
-#[cfg(feature = "bumpalo")]
-#[test]
-fn test_bumpalo() {
-    use bumpalo::Bump;
-    let bump = Bump::new();
-    let mut map = HashMap::new_in(BumpWrapper(&bump));
-    map.insert(0, 1);
-}
diff --git a/vendor/hashbrown/src/macros.rs b/vendor/hashbrown/src/macros.rs
index f8ef917b1..eaba6bed1 100644
--- a/vendor/hashbrown/src/macros.rs
+++ b/vendor/hashbrown/src/macros.rs
@@ -37,7 +37,7 @@ macro_rules! cfg_if {
     // 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 approprate #[cfg]. The
+        // 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)* }
diff --git a/vendor/hashbrown/src/map.rs b/vendor/hashbrown/src/map.rs
index e238bf66b..548ca0f9e 100644
--- a/vendor/hashbrown/src/map.rs
+++ b/vendor/hashbrown/src/map.rs
@@ -260,29 +260,6 @@ where
     hash_builder.hash_one(val)
 }
 
-#[cfg(not(feature = "nightly"))]
-#[cfg_attr(feature = "inline-more", inline)]
-pub(crate) fn make_insert_hash<K, S>(hash_builder: &S, val: &K) -> u64
-where
-    K: Hash,
-    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_insert_hash<K, S>(hash_builder: &S, val: &K) -> u64
-where
-    K: Hash,
-    S: BuildHasher,
-{
-    hash_builder.hash_one(val)
-}
-
 #[cfg(feature = "ahash")]
 impl<K, V> HashMap<K, V, DefaultHashBuilder> {
     /// Creates an empty `HashMap`.
@@ -368,13 +345,11 @@ impl<K, V, A: Allocator + Clone> HashMap<K, V, DefaultHashBuilder, A> {
     /// # Examples
     ///
     /// ```
-    /// # #[cfg(feature = "bumpalo")]
-    /// # fn test() {
-    /// use hashbrown::{HashMap, BumpWrapper};
+    /// use hashbrown::HashMap;
     /// use bumpalo::Bump;
     ///
     /// let bump = Bump::new();
-    /// let mut map = HashMap::new_in(BumpWrapper(&bump));
+    /// let mut map = HashMap::new_in(&bump);
     ///
     /// // The created HashMap holds none elements
     /// assert_eq!(map.len(), 0);
@@ -388,11 +363,6 @@ impl<K, V, A: Allocator + Clone> HashMap<K, V, DefaultHashBuilder, A> {
     /// assert_eq!(map.len(), 1);
     /// // And it also allocates some capacity
     /// assert!(map.capacity() > 1);
-    /// # }
-    /// # fn main() {
-    /// #     #[cfg(feature = "bumpalo")]
-    /// #     test()
-    /// # }
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn new_in(alloc: A) -> Self {
@@ -419,13 +389,11 @@ impl<K, V, A: Allocator + Clone> HashMap<K, V, DefaultHashBuilder, A> {
     /// # Examples
     ///
     /// ```
-    /// # #[cfg(feature = "bumpalo")]
-    /// # fn test() {
-    /// use hashbrown::{HashMap, BumpWrapper};
+    /// use hashbrown::HashMap;
     /// use bumpalo::Bump;
     ///
     /// let bump = Bump::new();
-    /// let mut map = HashMap::with_capacity_in(5, BumpWrapper(&bump));
+    /// let mut map = HashMap::with_capacity_in(5, &bump);
     ///
     /// // The created HashMap holds none elements
     /// assert_eq!(map.len(), 0);
@@ -444,11 +412,6 @@ impl<K, V, A: Allocator + Clone> HashMap<K, V, DefaultHashBuilder, A> {
     /// assert_eq!(map.len(), 5);
     /// // But its capacity isn't changed
     /// assert_eq!(map.capacity(), empty_map_capacity)
-    /// # }
-    /// # fn main() {
-    /// #     #[cfg(feature = "bumpalo")]
-    /// #     test()
-    /// # }
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
@@ -972,15 +935,12 @@ impl<K, V, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     /// In other words, move all pairs `(k, v)` such that `f(&k, &mut v)` returns `true` out
     /// into another iterator.
     ///
-    /// Note that `drain_filter` lets you mutate every value in the filter closure, regardless of
+    /// Note that `extract_if` lets you mutate every value in the filter closure, regardless of
     /// whether you choose to keep or remove it.
     ///
-    /// When the returned DrainedFilter is dropped, any remaining elements that satisfy
-    /// the predicate are dropped from the table.
-    ///
-    /// It is unspecified how many more elements will be subjected to the closure
-    /// if a panic occurs in the closure, or a panic occurs while dropping an element,
-    /// or if the `DrainFilter` value is leaked.
+    /// 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.
     ///
@@ -991,7 +951,7 @@ impl<K, V, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     ///
     /// let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
     ///
-    /// let drained: HashMap<i32, i32> = map.drain_filter(|k, _v| k % 2 == 0).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<_>>();
@@ -1004,21 +964,20 @@ impl<K, V, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     /// let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
     ///
     /// {   // Iterator is dropped without being consumed.
-    ///     let d = map.drain_filter(|k, _v| k % 2 != 0);
+    ///     let d = map.extract_if(|k, _v| k % 2 != 0);
     /// }
     ///
-    /// // But the map lens have been reduced by half
-    /// // even if we do not use DrainFilter iterator.
-    /// assert_eq!(map.len(), 4);
+    /// // ExtractIf was not exhausted, therefore no elements were drained.
+    /// assert_eq!(map.len(), 8);
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn drain_filter<F>(&mut self, f: F) -> DrainFilter<'_, K, V, F, A>
+    pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, K, V, F, A>
     where
         F: FnMut(&K, &mut V) -> bool,
     {
-        DrainFilter {
+        ExtractIf {
             f,
-            inner: DrainFilterInner {
+            inner: ExtractIfInner {
                 iter: unsafe { self.table.iter() },
                 table: &mut self.table,
             },
@@ -1266,7 +1225,7 @@ where
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn entry(&mut self, key: K) -> Entry<'_, K, V, S, A> {
-        let hash = make_insert_hash::<K, S>(&self.hash_builder, &key);
+        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,
@@ -1348,7 +1307,7 @@ where
     {
         // Avoid `Option::map` because it bloats LLVM IR.
         match self.get_inner(k) {
-            Some(&(_, ref v)) => Some(v),
+            Some((_, v)) => Some(v),
             None => None,
         }
     }
@@ -1379,7 +1338,7 @@ where
     {
         // Avoid `Option::map` because it bloats LLVM IR.
         match self.get_inner(k) {
-            Some(&(ref key, ref value)) => Some((key, value)),
+            Some((key, value)) => Some((key, value)),
             None => None,
         }
     }
@@ -1786,13 +1745,19 @@ where
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn insert(&mut self, k: K, v: V) -> Option<V> {
-        let hash = make_insert_hash::<K, S>(&self.hash_builder, &k);
-        if let Some((_, item)) = self.table.get_mut(hash, equivalent_key(&k)) {
-            Some(mem::replace(item, v))
-        } else {
-            self.table
-                .insert(hash, (k, v), make_hasher::<_, V, S>(&self.hash_builder));
-            None
+        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
+            }
         }
     }
 
@@ -1847,7 +1812,7 @@ where
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V) {
-        let hash = make_insert_hash::<K, S>(&self.hash_builder, &k);
+        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));
@@ -2123,6 +2088,18 @@ impl<K, V, S, A: Allocator + Clone> HashMap<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.
     ///
@@ -2159,9 +2136,9 @@ impl<K, V, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     /// where
     ///     F: Fn(&(K, V)) -> bool,
     /// {
-    ///     let raw_table = map.raw_table();
+    ///     let raw_table = map.raw_table_mut();
     ///     match raw_table.find(hash, is_match) {
-    ///         Some(bucket) => Some(unsafe { raw_table.remove(bucket) }),
+    ///         Some(bucket) => Some(unsafe { raw_table.remove(bucket).0 }),
     ///         None => None,
     ///     }
     /// }
@@ -2180,7 +2157,7 @@ impl<K, V, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     /// ```
     #[cfg(feature = "raw")]
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn raw_table(&mut self) -> &mut RawTable<(K, V), A> {
+    pub fn raw_table_mut(&mut self) -> &mut RawTable<(K, V), A> {
         &mut self.table
     }
 }
@@ -2711,10 +2688,10 @@ impl<K, V, A: Allocator + Clone> Drain<'_, K, V, A> {
 /// 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 [`drain_filter`] method on [`HashMap`]. See its
+/// This `struct` is created by the [`extract_if`] method on [`HashMap`]. See its
 /// documentation for more.
 ///
-/// [`drain_filter`]: struct.HashMap.html#method.drain_filter
+/// [`extract_if`]: struct.HashMap.html#method.extract_if
 /// [`HashMap`]: struct.HashMap.html
 ///
 /// # Examples
@@ -2724,54 +2701,31 @@ impl<K, V, A: Allocator + Clone> Drain<'_, K, V, A> {
 ///
 /// let mut map: HashMap<i32, &str> = [(1, "a"), (2, "b"), (3, "c")].into();
 ///
-/// let mut drain_filter = map.drain_filter(|k, _v| k % 2 != 0);
-/// let mut vec = vec![drain_filter.next(), drain_filter.next()];
+/// let mut extract_if = map.extract_if(|k, _v| k % 2 != 0);
+/// let mut vec = vec![extract_if.next(), extract_if.next()];
 ///
-/// // The `DrainFilter` iterator produces items in arbitrary order, so the
+/// // 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!(drain_filter.next(), None);
-/// assert_eq!(drain_filter.next(), None);
-/// drop(drain_filter);
+/// assert_eq!(extract_if.next(), None);
+/// assert_eq!(extract_if.next(), None);
+/// drop(extract_if);
 ///
 /// assert_eq!(map.len(), 1);
 /// ```
-pub struct DrainFilter<'a, K, V, F, A: Allocator + Clone = Global>
+#[must_use = "Iterators are lazy unless consumed"]
+pub struct ExtractIf<'a, K, V, F, A: Allocator + Clone = Global>
 where
     F: FnMut(&K, &mut V) -> bool,
 {
     f: F,
-    inner: DrainFilterInner<'a, K, V, A>,
-}
-
-impl<'a, K, V, F, A> Drop for DrainFilter<'a, K, V, F, A>
-where
-    F: FnMut(&K, &mut V) -> bool,
-    A: Allocator + Clone,
-{
-    #[cfg_attr(feature = "inline-more", inline)]
-    fn drop(&mut self) {
-        while let Some(item) = self.next() {
-            let guard = ConsumeAllOnDrop(self);
-            drop(item);
-            mem::forget(guard);
-        }
-    }
+    inner: ExtractIfInner<'a, K, V, A>,
 }
 
-pub(super) struct ConsumeAllOnDrop<'a, T: Iterator>(pub &'a mut T);
-
-impl<T: Iterator> Drop for ConsumeAllOnDrop<'_, T> {
-    #[cfg_attr(feature = "inline-more", inline)]
-    fn drop(&mut self) {
-        self.0.for_each(drop);
-    }
-}
-
-impl<K, V, F, A> Iterator for DrainFilter<'_, K, V, F, A>
+impl<K, V, F, A> Iterator for ExtractIf<'_, K, V, F, A>
 where
     F: FnMut(&K, &mut V) -> bool,
     A: Allocator + Clone,
@@ -2789,15 +2743,15 @@ where
     }
 }
 
-impl<K, V, F> FusedIterator for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
+impl<K, V, F> FusedIterator for ExtractIf<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
 
-/// Portions of `DrainFilter` shared with `set::DrainFilter`
-pub(super) struct DrainFilterInner<'a, K, V, A: Allocator + Clone> {
+/// Portions of `ExtractIf` shared with `set::ExtractIf`
+pub(super) struct ExtractIfInner<'a, K, V, A: Allocator + Clone> {
     pub iter: RawIter<(K, V)>,
     pub table: &'a mut RawTable<(K, V), A>,
 }
 
-impl<K, V, A: Allocator + Clone> DrainFilterInner<'_, K, V, A> {
+impl<K, V, A: Allocator + Clone> ExtractIfInner<'_, K, V, A> {
     #[cfg_attr(feature = "inline-more", inline)]
     pub(super) fn next<F>(&mut self, f: &mut F) -> Option<(K, V)>
     where
@@ -2807,7 +2761,7 @@ impl<K, V, A: Allocator + Clone> DrainFilterInner<'_, K, V, A> {
             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));
+                    return Some(self.table.remove(item).0);
                 }
             }
         }
@@ -3360,7 +3314,7 @@ impl<'a, K, V, S, A: Allocator + Clone> RawEntryBuilder<'a, K, V, S, A> {
         F: FnMut(&K) -> bool,
     {
         match self.map.table.get(hash, |(k, _)| is_match(k)) {
-            Some(&(ref key, ref value)) => Some((key, value)),
+            Some((key, value)) => Some((key, value)),
             None => None,
         }
     }
@@ -3756,7 +3710,7 @@ impl<'a, K, V, S, A: Allocator + Clone> RawOccupiedEntryMut<'a, K, V, S, A> {
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn get_key_value(&self) -> (&K, &V) {
         unsafe {
-            let &(ref key, ref value) = self.elem.as_ref();
+            let (key, value) = self.elem.as_ref();
             (key, value)
         }
     }
@@ -3928,7 +3882,7 @@ impl<'a, K, V, S, A: Allocator + Clone> RawOccupiedEntryMut<'a, K, V, S, A> {
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn remove_entry(self) -> (K, V) {
-        unsafe { self.table.remove(self.elem) }
+        unsafe { self.table.remove(self.elem).0 }
     }
 
     /// Provides shared access to the key and owned access to the value of
@@ -4012,7 +3966,7 @@ impl<'a, K, V, S, A: Allocator + Clone> RawVacantEntryMut<'a, K, V, S, A> {
         K: Hash,
         S: BuildHasher,
     {
-        let hash = make_insert_hash::<K, S>(self.hash_builder, &key);
+        let hash = make_hash::<K, S>(self.hash_builder, &key);
         self.insert_hashed_nocheck(hash, key, value)
     }
 
@@ -4120,7 +4074,7 @@ impl<'a, K, V, S, A: Allocator + Clone> RawVacantEntryMut<'a, K, V, S, A> {
         K: Hash,
         S: BuildHasher,
     {
-        let hash = make_insert_hash::<K, S>(self.hash_builder, &key);
+        let hash = make_hash::<K, S>(self.hash_builder, &key);
         let elem = self.table.insert(
             hash,
             (key, value),
@@ -4297,7 +4251,7 @@ impl<K: Debug, V: Debug, S, A: Allocator + Clone> Debug for Entry<'_, K, V, S, A
 /// assert_eq!(map.get(&"c"), None);
 /// assert_eq!(map.len(), 2);
 /// ```
-pub struct OccupiedEntry<'a, K, V, S, A: Allocator + Clone = Global> {
+pub struct OccupiedEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator + Clone = Global> {
     hash: u64,
     key: Option<K>,
     elem: Bucket<(K, V)>,
@@ -4360,7 +4314,7 @@ impl<K: Debug, V: Debug, S, A: Allocator + Clone> Debug for OccupiedEntry<'_, K,
 /// }
 /// assert!(map[&"b"] == 20 && map.len() == 2);
 /// ```
-pub struct VacantEntry<'a, K, V, S, A: Allocator + Clone = Global> {
+pub struct VacantEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator + Clone = Global> {
     hash: u64,
     key: K,
     table: &'a mut HashMap<K, V, S, A>,
@@ -4568,7 +4522,7 @@ impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator + Clone> Debug
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("OccupiedEntryRef")
-            .field("key", &self.key())
+            .field("key", &self.key().borrow())
             .field("value", &self.get())
             .finish()
     }
@@ -5301,7 +5255,7 @@ impl<'a, K, V, S, A: Allocator + Clone> OccupiedEntry<'a, K, V, S, A> {
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn remove_entry(self) -> (K, V) {
-        unsafe { self.table.table.remove(self.elem) }
+        unsafe { self.table.table.remove(self.elem).0 }
     }
 
     /// Gets a reference to the value in the entry.
@@ -5838,7 +5792,7 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> EntryRef<'a, 'b, K, Q, V,
         K: Borrow<Q>,
     {
         match *self {
-            EntryRef::Occupied(ref entry) => entry.key(),
+            EntryRef::Occupied(ref entry) => entry.key().borrow(),
             EntryRef::Vacant(ref entry) => entry.key(),
         }
     }
@@ -5934,8 +5888,7 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> EntryRef<'a, 'b, K, Q, V,
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn and_replace_entry_with<F>(self, f: F) -> Self
     where
-        F: FnOnce(&Q, V) -> Option<V>,
-        K: Borrow<Q>,
+        F: FnOnce(&K, V) -> Option<V>,
     {
         match self {
             EntryRef::Occupied(entry) => entry.replace_entry_with(f),
@@ -5994,11 +5947,8 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> OccupiedEntryRef<'a, 'b,
     /// }
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn key(&self) -> &Q
-    where
-        K: Borrow<Q>,
-    {
-        unsafe { &self.elem.as_ref().0 }.borrow()
+    pub fn key(&self) -> &K {
+        unsafe { &self.elem.as_ref().0 }
     }
 
     /// Take the ownership of the key and value from the map.
@@ -6027,7 +5977,7 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> OccupiedEntryRef<'a, 'b,
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn remove_entry(self) -> (K, V) {
-        unsafe { self.table.table.remove(self.elem) }
+        unsafe { self.table.table.remove(self.elem).0 }
     }
 
     /// Gets a reference to the value in the entry.
@@ -6303,8 +6253,7 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> OccupiedEntryRef<'a, 'b,
     #[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(&Q, V) -> Option<V>,
-        K: Borrow<Q>,
+        F: FnOnce(&K, V) -> Option<V>,
     {
         unsafe {
             let mut spare_key = None;
@@ -6312,7 +6261,7 @@ impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> OccupiedEntryRef<'a, 'b,
             self.table
                 .table
                 .replace_bucket_with(self.elem.clone(), |(key, value)| {
-                    if let Some(new_value) = f(key.borrow(), value) {
+                    if let Some(new_value) = f(&key, value) {
                         Some((key, new_value))
                     } else {
                         spare_key = Some(KeyOrRef::Owned(key));
@@ -6926,7 +6875,6 @@ mod test_map {
                 }
             });
 
-            #[allow(clippy::let_underscore_drop)] // kind-of a false positive
             for _ in half.by_ref() {}
 
             DROP_VECTOR.with(|v| {
@@ -7254,10 +7202,10 @@ mod test_map {
         map.insert(1, 2);
         map.insert(3, 4);
 
-        let map_str = format!("{:?}", map);
+        let map_str = format!("{map:?}");
 
         assert!(map_str == "{1: 2, 3: 4}" || map_str == "{3: 4, 1: 2}");
-        assert_eq!(format!("{:?}", empty), "{}");
+        assert_eq!(format!("{empty:?}"), "{}");
     }
 
     #[test]
@@ -7573,7 +7521,7 @@ mod test_map {
                               // Test for #19292
         fn check(m: &HashMap<i32, ()>) {
             for k in m.keys() {
-                assert!(m.contains_key(k), "{} is in keys() but not in the map?", k);
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
             }
         }
 
@@ -7609,7 +7557,7 @@ mod test_map {
                               // Test for #19292
         fn check(m: &HashMap<std::string::String, ()>) {
             for k in m.keys() {
-                assert!(m.contains_key(k), "{} is in keys() but not in the map?", k);
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
             }
         }
 
@@ -7658,6 +7606,7 @@ mod test_map {
     }
 
     #[test]
+    #[allow(clippy::needless_borrow)]
     fn test_extend_ref_kv_tuple() {
         use std::ops::AddAssign;
         let mut a = HashMap::new();
@@ -8080,7 +8029,7 @@ mod test_map {
                               // Test for #19292
         fn check(m: &HashMap<i32, ()>) {
             for k in m.keys() {
-                assert!(m.contains_key(k), "{} is in keys() but not in the map?", k);
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
             }
         }
 
@@ -8110,7 +8059,7 @@ mod test_map {
                               // Test for #19292
         fn check(m: &HashMap<std::string::String, ()>) {
             for k in m.keys() {
-                assert!(m.contains_key(k), "{} is in keys() but not in the map?", k);
+                assert!(m.contains_key(k), "{k} is in keys() but not in the map?");
             }
         }
 
@@ -8148,10 +8097,10 @@ mod test_map {
     }
 
     #[test]
-    fn test_drain_filter() {
+    fn test_extract_if() {
         {
             let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x * 10)).collect();
-            let drained = map.drain_filter(|&k, _| k % 2 == 0);
+            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);
@@ -8159,7 +8108,7 @@ mod test_map {
         }
         {
             let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x * 10)).collect();
-            drop(map.drain_filter(|&k, _| k % 2 == 0));
+            map.extract_if(|&k, _| k % 2 == 0).for_each(drop);
             assert_eq!(map.len(), 4);
         }
     }
@@ -8208,7 +8157,7 @@ mod test_map {
         let mut map: HashMap<_, _> = xs.iter().copied().collect();
 
         let compute_hash = |map: &HashMap<i32, i32>, k: i32| -> u64 {
-            super::make_insert_hash::<i32, _>(map.hasher(), &k)
+            super::make_hash::<i32, _>(map.hasher(), &k)
         };
 
         // Existing key (insert)
@@ -8370,17 +8319,17 @@ mod test_map {
             loop {
                 // occasionally remove some elements
                 if i < n && rng.gen_bool(0.1) {
-                    let hash_value = super::make_insert_hash(&hash_builder, &i);
+                    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);
+                            let t = map.table.remove(e).0;
                             removed.push(t);
                             left -= 1;
                         } else {
-                            assert!(removed.contains(&(i, 2 * i)), "{} not in {:?}", i, removed);
+                            assert!(removed.contains(&(i, 2 * i)), "{i} not in {removed:?}");
                             let e = map.table.insert(
                                 hash_value,
                                 (i, 2 * i),
@@ -8509,4 +8458,49 @@ mod test_map {
 
         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();
+    }
 }
diff --git a/vendor/hashbrown/src/raw/alloc.rs b/vendor/hashbrown/src/raw/alloc.rs
index ba09ea9de..15299e7b0 100644
--- a/vendor/hashbrown/src/raw/alloc.rs
+++ b/vendor/hashbrown/src/raw/alloc.rs
@@ -1,5 +1,9 @@
 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;
@@ -7,28 +11,44 @@ mod inner {
     use core::ptr::NonNull;
 
     #[allow(clippy::map_err_ignore)]
-    pub fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
+    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(()),
         }
     }
+}
 
-    #[cfg(feature = "bumpalo")]
-    unsafe impl Allocator for crate::BumpWrapper<'_> {
-        #[inline]
-        fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, core::alloc::AllocError> {
-            match self.0.try_alloc_layout(layout) {
-                Ok(ptr) => Ok(NonNull::slice_from_raw_parts(ptr, layout.size())),
-                Err(_) => Err(core::alloc::AllocError),
-            }
+// 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(()),
         }
-        #[inline]
-        unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {}
     }
 }
 
-#[cfg(not(feature = "nightly"))]
+// 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;
@@ -41,6 +61,7 @@ mod inner {
 
     #[derive(Copy, Clone)]
     pub struct Global;
+
     unsafe impl Allocator for Global {
         #[inline]
         fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()> {
@@ -51,6 +72,7 @@ mod inner {
             dealloc(ptr.as_ptr(), layout);
         }
     }
+
     impl Default for Global {
         #[inline]
         fn default() -> Self {
@@ -58,16 +80,7 @@ mod inner {
         }
     }
 
-    pub fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
+    pub(crate) fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
         alloc.allocate(layout)
     }
-
-    #[cfg(feature = "bumpalo")]
-    unsafe impl Allocator for crate::BumpWrapper<'_> {
-        #[allow(clippy::map_err_ignore)]
-        fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, ()> {
-            self.0.try_alloc_layout(layout).map_err(|_| ())
-        }
-        unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {}
-    }
 }
diff --git a/vendor/hashbrown/src/raw/bitmask.rs b/vendor/hashbrown/src/raw/bitmask.rs
index 7d4f9fc38..6576b3c5c 100644
--- a/vendor/hashbrown/src/raw/bitmask.rs
+++ b/vendor/hashbrown/src/raw/bitmask.rs
@@ -1,6 +1,6 @@
-use super::imp::{BitMaskWord, BITMASK_MASK, BITMASK_STRIDE};
-#[cfg(feature = "nightly")]
-use core::intrinsics;
+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.
@@ -8,75 +8,55 @@ use core::intrinsics;
 /// 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, so
-/// that there is only one bit-per-byte used (the high bit, 7). If this is the
+/// 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 struct BitMask(pub BitMaskWord);
+pub(crate) struct BitMask(pub(crate) BitMaskWord);
 
 #[allow(clippy::use_self)]
 impl BitMask {
     /// Returns a new `BitMask` with all bits inverted.
     #[inline]
     #[must_use]
-    pub fn invert(self) -> Self {
+    #[allow(dead_code)]
+    pub(crate) fn invert(self) -> Self {
         BitMask(self.0 ^ BITMASK_MASK)
     }
 
-    /// 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 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 ^= mask;
-        // The bit was set if the bit is now 0.
-        self.0 & mask == 0
-    }
-
     /// Returns a new `BitMask` with the lowest bit removed.
     #[inline]
     #[must_use]
-    pub fn remove_lowest_bit(self) -> Self {
+    fn remove_lowest_bit(self) -> Self {
         BitMask(self.0 & (self.0 - 1))
     }
+
     /// Returns whether the `BitMask` has at least one set bit.
     #[inline]
-    pub fn any_bit_set(self) -> bool {
+    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 fn lowest_set_bit(self) -> Option<usize> {
-        if self.0 == 0 {
-            None
+    pub(crate) fn lowest_set_bit(self) -> Option<usize> {
+        if let Some(nonzero) = NonZeroBitMaskWord::new(self.0) {
+            Some(Self::nonzero_trailing_zeros(nonzero))
         } else {
-            Some(unsafe { self.lowest_set_bit_nonzero() })
+            None
         }
     }
 
-    /// Returns the first set bit in the `BitMask`, if there is one. The
-    /// bitmask must not be empty.
-    #[inline]
-    #[cfg(feature = "nightly")]
-    pub unsafe fn lowest_set_bit_nonzero(self) -> usize {
-        intrinsics::cttz_nonzero(self.0) as usize / BITMASK_STRIDE
-    }
-    #[inline]
-    #[cfg(not(feature = "nightly"))]
-    pub unsafe fn lowest_set_bit_nonzero(self) -> usize {
-        self.trailing_zeros()
-    }
-
     /// Returns the number of trailing zeroes in the `BitMask`.
     #[inline]
-    pub fn trailing_zeros(self) -> usize {
+    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
@@ -89,9 +69,21 @@ impl BitMask {
         }
     }
 
+    /// 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 fn leading_zeros(self) -> usize {
+    pub(crate) fn leading_zeros(self) -> usize {
         self.0.leading_zeros() as usize / BITMASK_STRIDE
     }
 }
@@ -102,13 +94,32 @@ impl IntoIterator for BitMask {
 
     #[inline]
     fn into_iter(self) -> BitMaskIter {
-        BitMaskIter(self)
+        // 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.
-pub struct BitMaskIter(BitMask);
+#[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;
diff --git a/vendor/hashbrown/src/raw/generic.rs b/vendor/hashbrown/src/raw/generic.rs
index 52955a45b..c668b0642 100644
--- a/vendor/hashbrown/src/raw/generic.rs
+++ b/vendor/hashbrown/src/raw/generic.rs
@@ -5,26 +5,29 @@ 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(any(
-    target_pointer_width = "64",
-    target_arch = "aarch64",
-    target_arch = "x86_64",
-    target_arch = "wasm32",
-))]
-type GroupWord = u64;
-#[cfg(all(
-    any(target_pointer_width = "32", target_pointer_width = "16"),
-    not(target_arch = "aarch64"),
-    not(target_arch = "x86_64"),
-    not(target_arch = "wasm32"),
-))]
-type GroupWord = u32;
 
-pub type BitMaskWord = GroupWord;
-pub const BITMASK_STRIDE: usize = 8;
+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 const BITMASK_MASK: BitMaskWord = 0x8080_8080_8080_8080_u64 as GroupWord;
+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]
@@ -37,7 +40,7 @@ fn repeat(byte: u8) -> GroupWord {
 ///
 /// This implementation uses a word-sized integer.
 #[derive(Copy, Clone)]
-pub struct Group(GroupWord);
+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
@@ -46,14 +49,14 @@ pub struct Group(GroupWord);
 #[allow(clippy::use_self)]
 impl Group {
     /// Number of bytes in the group.
-    pub const WIDTH: usize = mem::size_of::<Self>();
+    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 const fn static_empty() -> &'static [u8; Group::WIDTH] {
+    pub(crate) const fn static_empty() -> &'static [u8; Group::WIDTH] {
         #[repr(C)]
         struct AlignedBytes {
             _align: [Group; 0],
@@ -69,7 +72,7 @@ impl Group {
     /// Loads a group of bytes starting at the given address.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)] // unaligned load
-    pub unsafe fn load(ptr: *const u8) -> Self {
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
         Group(ptr::read_unaligned(ptr.cast()))
     }
 
@@ -77,7 +80,7 @@ impl Group {
     /// aligned to `mem::align_of::<Group>()`.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)]
-    pub unsafe fn load_aligned(ptr: *const u8) -> Self {
+    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()))
@@ -87,7 +90,7 @@ impl Group {
     /// aligned to `mem::align_of::<Group>()`.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)]
-    pub unsafe fn store_aligned(self, ptr: *mut u8) {
+    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);
@@ -104,7 +107,7 @@ impl Group {
     /// - 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 fn match_byte(self, byte: u8) -> BitMask {
+    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);
@@ -114,7 +117,7 @@ impl Group {
     /// Returns a `BitMask` indicating all bytes in the group which are
     /// `EMPTY`.
     #[inline]
-    pub fn match_empty(self) -> BitMask {
+    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.
@@ -124,14 +127,14 @@ impl Group {
     /// Returns a `BitMask` indicating all bytes in the group which are
     /// `EMPTY` or `DELETED`.
     #[inline]
-    pub fn match_empty_or_deleted(self) -> BitMask {
+    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 fn match_full(self) -> BitMask {
+    pub(crate) fn match_full(self) -> BitMask {
         self.match_empty_or_deleted().invert()
     }
 
@@ -140,7 +143,7 @@ impl Group {
     /// - `DELETED => EMPTY`
     /// - `FULL => DELETED`
     #[inline]
-    pub fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+    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
         //
diff --git a/vendor/hashbrown/src/raw/mod.rs b/vendor/hashbrown/src/raw/mod.rs
index 0e96306ef..1a6dced4b 100644
--- a/vendor/hashbrown/src/raw/mod.rs
+++ b/vendor/hashbrown/src/raw/mod.rs
@@ -25,8 +25,10 @@ cfg_if! {
     ))] {
         mod sse2;
         use sse2 as imp;
+    } else if #[cfg(all(target_arch = "aarch64", target_feature = "neon"))] {
+        mod neon;
+        use neon as imp;
     } else {
-        #[path = "generic.rs"]
         mod generic;
         use generic as imp;
     }
@@ -37,36 +39,26 @@ pub(crate) use self::alloc::{do_alloc, Allocator, Global};
 
 mod bitmask;
 
-use self::bitmask::{BitMask, BitMaskIter};
+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};
 
-// On stable we can use #[cold] to get a equivalent effect: this attributes
-// suggests that the function is unlikely to be called
-#[cfg(not(feature = "nightly"))]
-#[inline]
-#[cold]
-fn cold() {}
-
-#[cfg(not(feature = "nightly"))]
-#[inline]
-fn likely(b: bool) -> bool {
-    if !b {
-        cold();
-    }
-    b
-}
+// 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]
-fn unlikely(b: bool) -> bool {
-    if b {
-        cold();
-    }
-    b
+#[inline(always)]
+fn invalid_mut<T>(addr: usize) -> *mut T {
+    addr as *mut T
 }
 
 #[inline]
@@ -272,6 +264,11 @@ impl TableLayout {
     }
 }
 
+/// 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
@@ -299,11 +296,79 @@ impl<T> Clone for Bucket<T> {
 impl<T> Bucket<T> {
     const IS_ZERO_SIZED_TYPE: bool = mem::size_of::<T>() == 0;
 
+    /// 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 Self::IS_ZERO_SIZED_TYPE {
-            // won't overflow because index must be less than length
-            (index + 1) as *mut T
+            // 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)
         };
@@ -311,27 +376,183 @@ impl<T> Bucket<T> {
             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 Self::IS_ZERO_SIZED_TYPE {
+            // 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 Self::IS_ZERO_SIZED_TYPE {
             // Just return an arbitrary ZST pointer which is properly aligned
-            mem::align_of::<T>() as *mut T
+            // 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 Self::IS_ZERO_SIZED_TYPE {
-            (self.ptr.as_ptr() as usize + offset) as *mut T
+            // invalid pointer is good enough for ZST
+            invalid_mut(self.ptr.as_ptr() as usize + offset)
         } else {
             self.ptr.as_ptr().sub(offset)
         };
@@ -339,26 +560,212 @@ impl<T> Bucket<T> {
             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) {
@@ -516,9 +923,9 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
 
     /// Returns pointer to start of data table.
     #[inline]
-    #[cfg(feature = "nightly")]
-    pub unsafe fn data_start(&self) -> *mut T {
-        self.data_end().as_ptr().wrapping_sub(self.buckets())
+    #[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.
@@ -581,11 +988,18 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     }
 
     /// 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 {
+    pub unsafe fn remove(&mut self, item: Bucket<T>) -> (T, InsertSlot) {
         self.erase_no_drop(&item);
-        item.read()
+        (
+            item.read(),
+            InsertSlot {
+                index: self.bucket_index(&item),
+            },
+        )
     }
 
     /// Finds and removes an element from the table, returning it.
@@ -593,7 +1007,7 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     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) }),
+            Some(bucket) => Some(unsafe { self.remove(bucket).0 }),
             None => None,
         }
     }
@@ -607,6 +1021,10 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     /// 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 {
@@ -663,7 +1081,7 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     /// without reallocation.
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn reserve(&mut self, additional: usize, hasher: impl Fn(&T) -> u64) {
-        if additional > self.table.growth_left {
+        if unlikely(additional > self.table.growth_left) {
             // Avoid `Result::unwrap_or_else` because it bloats LLVM IR.
             if self
                 .reserve_rehash(additional, hasher, Fallibility::Infallible)
@@ -737,22 +1155,18 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn insert(&mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64) -> Bucket<T> {
         unsafe {
-            let mut index = self.table.find_insert_slot(hash);
+            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.
-            let old_ctrl = *self.table.ctrl(index);
+            let old_ctrl = *self.table.ctrl(slot.index);
             if unlikely(self.table.growth_left == 0 && special_is_empty(old_ctrl)) {
                 self.reserve(1, hasher);
-                index = self.table.find_insert_slot(hash);
+                slot = self.table.find_insert_slot(hash);
             }
 
-            self.table.record_item_insert_at(index, old_ctrl, hash);
-
-            let bucket = self.bucket(index);
-            bucket.write(value);
-            bucket
+            self.insert_in_slot(hash, slot, value)
         }
     }
 
@@ -820,7 +1234,7 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
         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);
+        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);
@@ -832,6 +1246,49 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
         }
     }
 
+    /// 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);
+
+        match self
+            .table
+            .find_or_find_insert_slot_inner(hash, &mut |index| unsafe {
+                eq(self.bucket(index).as_ref())
+            }) {
+            Ok(index) => Ok(unsafe { 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>> {
@@ -984,7 +1441,7 @@ impl<T, A: Allocator + Clone> RawTable<T, A> {
     /// `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, A> {
+    pub unsafe fn iter_hash(&self, hash: u64) -> RawIterHash<T> {
         RawIterHash::new(self, hash)
     }
 
@@ -1072,6 +1529,11 @@ where
 }
 
 impl<A> RawTableInner<A> {
+    /// 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_in(alloc: A) -> Self {
         Self {
@@ -1086,6 +1548,18 @@ impl<A> RawTableInner<A> {
 }
 
 impl<A: Allocator + Clone> RawTableInner<A> {
+    /// 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(
         alloc: A,
@@ -1106,6 +1580,7 @@ impl<A: Allocator + Clone> RawTableInner<A> {
             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,
@@ -1116,6 +1591,10 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         })
     }
 
+    /// 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(
         alloc: A,
@@ -1126,11 +1605,16 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         if capacity == 0 {
             Ok(Self::new_in(alloc))
         } 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)
@@ -1138,66 +1622,200 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         }
     }
 
+    /// Fixes up an insertion slot due to false positives for groups smaller than the group width.
+    /// This must only be used on insertion slots found by `find_insert_slot_in_group`.
+    #[inline]
+    unsafe fn fix_insert_slot(&self, mut index: usize) -> InsertSlot {
+        // 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, but once masked 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).
+        if unlikely(self.is_bucket_full(index)) {
+            debug_assert!(self.bucket_mask < Group::WIDTH);
+            // SAFETY:
+            //
+            // * We are in range and `ptr = self.ctrl(0)` are valid for reads
+            //   and properly aligned, because the table is already allocated
+            //   (see `TableLayout::calculate_layout_for` and `ptr::read`);
+            //
+            // * 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, 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.
+    #[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()) {
+            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.
+    ///
+    /// This uses dynamic dispatch to reduce the amount of code generated, but that is
+    /// eliminated by LLVM optimizations.
+    #[inline]
+    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 {
+            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 {
+                    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.
     ///
     /// There must be at least 1 empty bucket in the table.
     #[inline]
     unsafe fn prepare_insert_slot(&self, hash: u64) -> (usize, u8) {
-        let index = self.find_insert_slot(hash);
+        let index = self.find_insert_slot(hash).index;
         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.
+    /// a new element, returning the `index` for the new [`Bucket`].
     ///
-    /// There must be at least 1 empty bucket in the table.
+    /// 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.
+    ///
+    /// # Note
+    ///
+    /// Calling this function is always safe, but attempting 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 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]
-    fn find_insert_slot(&self, hash: u64) -> usize {
+    fn find_insert_slot(&self, hash: u64) -> InsertSlot {
         let mut probe_seq = self.probe_seq(hash);
         loop {
+            // SAFETY:
+            // * `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 comment for masking below).
+            //
+            // * 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).
             unsafe {
                 let group = Group::load(self.ctrl(probe_seq.pos));
-                if let Some(bit) = group.match_empty_or_deleted().lowest_set_bit() {
-                    let result = (probe_seq.pos + bit) & self.bucket_mask;
-
-                    // In tables smaller than the group width, trailing control
-                    // bytes outside the range of the table are filled with
-                    // EMPTY entries. These will unfortunately trigger a
-                    // match, but once masked 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).
-                    if unlikely(self.is_bucket_full(result)) {
-                        debug_assert!(self.bucket_mask < Group::WIDTH);
-                        debug_assert_ne!(probe_seq.pos, 0);
-                        return Group::load_aligned(self.ctrl(0))
-                            .match_empty_or_deleted()
-                            .lowest_set_bit_nonzero();
-                    }
+                let index = self.find_insert_slot_in_group(&group, &probe_seq);
 
-                    return result;
+                if likely(index.is_some()) {
+                    return self.fix_insert_slot(index.unwrap_unchecked());
                 }
             }
             probe_seq.move_next(self.bucket_mask);
         }
     }
 
-    /// Searches for an element in the table. This uses dynamic dispatch to reduce the amount of
-    /// code generated, but it is eliminated by LLVM optimizations.
+    /// 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).
     #[inline(always)]
     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:
+            // * `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)) {
@@ -1213,12 +1831,49 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         }
     }
 
+    /// 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.
+    ///
+    /// 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.
+        // 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();
@@ -1227,10 +1882,19 @@ impl<A: Allocator + Clone> RawTableInner<A> {
 
         // Fix up the trailing control bytes. See the comments in set_ctrl
         // for the handling of tables smaller than the group width.
-        if self.buckets() < 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);
         }
@@ -1274,7 +1938,7 @@ impl<A: Allocator + Clone> RawTableInner<A> {
     #[cfg(feature = "raw")]
     #[inline]
     unsafe fn prepare_insert_no_grow(&mut self, hash: u64) -> Result<usize, ()> {
-        let index = self.find_insert_slot(hash);
+        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(())
@@ -1301,13 +1965,68 @@ impl<A: Allocator + Clone> RawTableInner<A> {
 
     /// 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(&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(&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
@@ -1315,6 +2034,28 @@ impl<A: Allocator + Clone> RawTableInner<A> {
 
     /// 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(&self, index: usize, ctrl: u8) {
         // Replicate the first Group::WIDTH control bytes at the end of
@@ -1335,16 +2076,43 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         // ---------------------------------------------
         // | [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)
     }
 
@@ -1541,7 +2309,7 @@ impl<A: Allocator + Clone> RawTableInner<A> {
                 let hash = hasher(*guard, i);
 
                 // Search for a suitable place to put it
-                let new_i = guard.find_insert_slot(hash);
+                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
@@ -1626,27 +2394,95 @@ impl<A: Allocator + Clone> RawTableInner<A> {
         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();
 
-        // If we are inside a continuous block of Group::WIDTH full or deleted
-        // cells then a probe window may have seen a full block when trying to
-        // insert. We therefore need to keep that block non-empty so that
-        // lookups will continue searching to the next probe window.
+        // 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:
         //
-        // 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.
+        // - 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;
     }
@@ -1752,7 +2588,8 @@ impl<T: Copy, A: Allocator + Clone> RawTableClone for RawTable<T, A> {
             .copy_to_nonoverlapping(self.table.ctrl(0), self.table.num_ctrl_bytes());
         source
             .data_start()
-            .copy_to_nonoverlapping(self.data_start(), self.table.buckets());
+            .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;
@@ -1776,7 +2613,7 @@ impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
         // to make sure we drop only the elements that have been
         // cloned so far.
         let mut guard = guard((0, &mut *self), |(index, self_)| {
-            if Self::DATA_NEEDS_DROP && !self_.is_empty() {
+            if Self::DATA_NEEDS_DROP {
                 for i in 0..=*index {
                     if self_.is_bucket_full(i) {
                         self_.bucket(i).drop();
@@ -1896,7 +2733,7 @@ impl<T, A: Allocator + Clone> IntoIterator for RawTable<T, A> {
 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: BitMask,
+    current_group: BitMaskIter,
 
     // Pointer to the buckets for the current group.
     data: Bucket<T>,
@@ -1924,7 +2761,7 @@ impl<T> RawIterRange<T> {
         let next_ctrl = ctrl.add(Group::WIDTH);
 
         Self {
-            current_group,
+            current_group: current_group.into_iter(),
             data,
             next_ctrl,
             end,
@@ -1981,8 +2818,7 @@ impl<T> RawIterRange<T> {
     #[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.lowest_set_bit() {
-                self.current_group = self.current_group.remove_lowest_bit();
+            if let Some(index) = self.current_group.next() {
                 return Some(self.data.next_n(index));
             }
 
@@ -1995,7 +2831,7 @@ impl<T> RawIterRange<T> {
             // 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();
+            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);
         }
@@ -2074,7 +2910,7 @@ impl<T> RawIter<T> {
     /// 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 fn reflect_remove(&mut self, b: &Bucket<T>) {
+    pub unsafe fn reflect_remove(&mut self, b: &Bucket<T>) {
         self.reflect_toggle_full(b, false);
     }
 
@@ -2088,36 +2924,76 @@ impl<T> RawIter<T> {
     ///
     /// This method should be called _after_ the given insert is made.
     #[cfg(feature = "raw")]
-    pub fn reflect_insert(&mut self, b: &Bucket<T>) {
+    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")]
-    fn reflect_toggle_full(&mut self, b: &Bucket<T>, is_insert: bool) {
-        unsafe {
-            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;
+    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 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 is_insert {
+                self.items += 1;
+            } else {
+                self.items -= 1;
+            }
 
-                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));
-                }
+            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;
@@ -2125,60 +3001,18 @@ impl<T> RawIter<T> {
                     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.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;
+                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 {
-                        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.lowest_set_bit(), Some(index));
-                        } else {
-                            // We should not have changed what bucket comes next.
-                            debug_assert_eq!(self.iter.current_group.lowest_set_bit(), Some(index));
-                        }
+                        // 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.
             }
+        } else {
+            // We must have already iterated past the removed item.
         }
     }
 
@@ -2217,9 +3051,8 @@ impl<T> Iterator for RawIter<T> {
             self.iter.next_impl::<false>()
         };
 
-        if nxt.is_some() {
-            self.items -= 1;
-        }
+        debug_assert!(nxt.is_some());
+        self.items -= 1;
 
         nxt
     }
@@ -2388,13 +3221,28 @@ impl<T, A: Allocator + Clone> FusedIterator for RawDrain<'_, T, A> {}
 /// `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.
-pub struct RawIterHash<'a, T, A: Allocator + Clone = Global> {
-    inner: RawIterHashInner<'a, A>,
+///
+/// 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<'a, A: Allocator + Clone> {
-    table: &'a RawTableInner<A>,
+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,
@@ -2408,65 +3256,77 @@ struct RawIterHashInner<'a, A: Allocator + Clone> {
     bitmask: BitMaskIter,
 }
 
-impl<'a, T, A: Allocator + Clone> RawIterHash<'a, T, A> {
+impl<T> RawIterHash<T> {
     #[cfg_attr(feature = "inline-more", inline)]
     #[cfg(feature = "raw")]
-    fn new(table: &'a RawTable<T, A>, hash: u64) -> Self {
+    unsafe fn new<A: Allocator + Clone>(table: &RawTable<T, A>, hash: u64) -> Self {
         RawIterHash {
             inner: RawIterHashInner::new(&table.table, hash),
             _marker: PhantomData,
         }
     }
 }
-impl<'a, A: Allocator + Clone> RawIterHashInner<'a, A> {
+impl RawIterHashInner {
     #[cfg_attr(feature = "inline-more", inline)]
     #[cfg(feature = "raw")]
-    fn new(table: &'a RawTableInner<A>, hash: u64) -> Self {
-        unsafe {
-            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 {
-                table,
-                h2_hash,
-                probe_seq,
-                group,
-                bitmask,
-            }
+    unsafe fn new<A: Allocator + Clone>(table: &RawTableInner<A>, 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<'a, T, A: Allocator + Clone> Iterator for RawIterHash<'a, T, A> {
+impl<T> Iterator for RawIterHash<T> {
     type Item = Bucket<T>;
 
     fn next(&mut self) -> Option<Bucket<T>> {
         unsafe {
             match self.inner.next() {
-                Some(index) => Some(self.inner.table.bucket(index)),
+                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<'a, A: Allocator + Clone> Iterator for RawIterHashInner<'a, A> {
+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.table.bucket_mask;
+                    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.table.bucket_mask);
-                self.group = Group::load(self.table.ctrl(self.probe_seq.pos));
+                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();
             }
         }
diff --git a/vendor/hashbrown/src/raw/neon.rs b/vendor/hashbrown/src/raw/neon.rs
new file mode 100644
index 000000000..44e82d57d
--- /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
index a0bf6da80..956ba5d26 100644
--- a/vendor/hashbrown/src/raw/sse2.rs
+++ b/vendor/hashbrown/src/raw/sse2.rs
@@ -1,28 +1,31 @@
 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 type BitMaskWord = u16;
-pub const BITMASK_STRIDE: usize = 1;
-pub const BITMASK_MASK: BitMaskWord = 0xffff;
+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 struct Group(x86::__m128i);
+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 const WIDTH: usize = mem::size_of::<Self>();
+    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.
@@ -30,7 +33,7 @@ impl Group {
     /// This is guaranteed to be aligned to the group size.
     #[inline]
     #[allow(clippy::items_after_statements)]
-    pub const fn static_empty() -> &'static [u8; Group::WIDTH] {
+    pub(crate) const fn static_empty() -> &'static [u8; Group::WIDTH] {
         #[repr(C)]
         struct AlignedBytes {
             _align: [Group; 0],
@@ -46,7 +49,7 @@ impl Group {
     /// Loads a group of bytes starting at the given address.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)] // unaligned load
-    pub unsafe fn load(ptr: *const u8) -> Self {
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
         Group(x86::_mm_loadu_si128(ptr.cast()))
     }
 
@@ -54,7 +57,7 @@ impl Group {
     /// aligned to `mem::align_of::<Group>()`.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)]
-    pub unsafe fn load_aligned(ptr: *const u8) -> Self {
+    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()))
@@ -64,7 +67,7 @@ impl Group {
     /// aligned to `mem::align_of::<Group>()`.
     #[inline]
     #[allow(clippy::cast_ptr_alignment)]
-    pub unsafe fn store_aligned(self, ptr: *mut u8) {
+    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);
@@ -73,7 +76,7 @@ impl Group {
     /// Returns a `BitMask` indicating all bytes in the group which have
     /// the given value.
     #[inline]
-    pub fn match_byte(self, byte: u8) -> BitMask {
+    pub(crate) fn match_byte(self, byte: u8) -> BitMask {
         #[allow(
             clippy::cast_possible_wrap, // byte: u8 as i8
             // byte: i32 as u16
@@ -91,14 +94,14 @@ impl Group {
     /// Returns a `BitMask` indicating all bytes in the group which are
     /// `EMPTY`.
     #[inline]
-    pub fn match_empty(self) -> BitMask {
+    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 fn match_empty_or_deleted(self) -> BitMask {
+    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
@@ -114,7 +117,7 @@ impl Group {
 
     /// Returns a `BitMask` indicating all bytes in the group which are full.
     #[inline]
-    pub fn match_full(&self) -> BitMask {
+    pub(crate) fn match_full(&self) -> BitMask {
         self.match_empty_or_deleted().invert()
     }
 
@@ -123,7 +126,7 @@ impl Group {
     /// - `DELETED => EMPTY`
     /// - `FULL => DELETED`
     #[inline]
-    pub fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
+    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
         //
diff --git a/vendor/hashbrown/src/rustc_entry.rs b/vendor/hashbrown/src/rustc_entry.rs
index 2e8459526..89447d27d 100644
--- a/vendor/hashbrown/src/rustc_entry.rs
+++ b/vendor/hashbrown/src/rustc_entry.rs
@@ -1,5 +1,5 @@
 use self::RustcEntry::*;
-use crate::map::{make_insert_hash, Drain, HashMap, IntoIter, Iter, IterMut};
+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};
@@ -32,7 +32,7 @@ where
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn rustc_entry(&mut self, key: K) -> RustcEntry<'_, K, V, A> {
-        let hash = make_insert_hash(&self.hash_builder, &key);
+        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),
@@ -330,7 +330,7 @@ impl<'a, K, V, A: Allocator + Clone> RustcOccupiedEntry<'a, K, V, A> {
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn remove_entry(self) -> (K, V) {
-        unsafe { self.table.remove(self.elem) }
+        unsafe { self.table.remove(self.elem).0 }
     }
 
     /// Gets a reference to the value in the entry.
diff --git a/vendor/hashbrown/src/set.rs b/vendor/hashbrown/src/set.rs
index a8f24de80..52f6fdaf2 100644
--- a/vendor/hashbrown/src/set.rs
+++ b/vendor/hashbrown/src/set.rs
@@ -5,10 +5,9 @@ use alloc::borrow::ToOwned;
 use core::fmt;
 use core::hash::{BuildHasher, Hash};
 use core::iter::{Chain, FromIterator, FusedIterator};
-use core::mem;
 use core::ops::{BitAnd, BitOr, BitXor, Sub};
 
-use super::map::{self, ConsumeAllOnDrop, DefaultHashBuilder, DrainFilterInner, HashMap, Keys};
+use super::map::{self, DefaultHashBuilder, ExtractIfInner, HashMap, Keys};
 use crate::raw::{Allocator, Global};
 
 // Future Optimization (FIXME!)
@@ -380,8 +379,9 @@ impl<T, S, A: Allocator + Clone> HashSet<T, S, A> {
     /// In other words, move all elements `e` such that `f(&e)` returns `true` out
     /// into another iterator.
     ///
-    /// When the returned DrainedFilter is dropped, any remaining elements that satisfy
-    /// the predicate are dropped from the set.
+    /// 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
     ///
@@ -389,7 +389,7 @@ impl<T, S, A: Allocator + Clone> HashSet<T, S, A> {
     /// use hashbrown::HashSet;
     ///
     /// let mut set: HashSet<i32> = (0..8).collect();
-    /// let drained: HashSet<i32> = set.drain_filter(|v| v % 2 == 0).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<_>>();
@@ -400,13 +400,13 @@ impl<T, S, A: Allocator + Clone> HashSet<T, S, A> {
     /// assert_eq!(odds, vec![1, 3, 5, 7]);
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
-    pub fn drain_filter<F>(&mut self, f: F) -> DrainFilter<'_, T, F, A>
+    pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, T, F, A>
     where
         F: FnMut(&T) -> bool,
     {
-        DrainFilter {
+        ExtractIf {
             f,
-            inner: DrainFilterInner {
+            inner: ExtractIfInner {
                 iter: unsafe { self.map.table.iter() },
                 table: &mut self.map.table,
             },
@@ -1221,8 +1221,10 @@ where
             None => None,
         }
     }
+}
 
-    /// Returns a mutable reference to the [`RawTable`] used underneath [`HashSet`].
+impl<T, S, A: Allocator + Clone> 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
@@ -1238,9 +1240,29 @@ where
     /// [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 self) -> &mut RawTable<(T, ()), A> {
+    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>
@@ -1547,17 +1569,18 @@ pub struct Drain<'a, K, A: Allocator + Clone = Global> {
 
 /// A draining iterator over entries of a `HashSet` which don't satisfy the predicate `f`.
 ///
-/// This `struct` is created by the [`drain_filter`] method on [`HashSet`]. See its
+/// This `struct` is created by the [`extract_if`] method on [`HashSet`]. See its
 /// documentation for more.
 ///
-/// [`drain_filter`]: struct.HashSet.html#method.drain_filter
+/// [`extract_if`]: struct.HashSet.html#method.extract_if
 /// [`HashSet`]: struct.HashSet.html
-pub struct DrainFilter<'a, K, F, A: Allocator + Clone = Global>
+#[must_use = "Iterators are lazy unless consumed"]
+pub struct ExtractIf<'a, K, F, A: Allocator + Clone = Global>
 where
     F: FnMut(&K) -> bool,
 {
     f: F,
-    inner: DrainFilterInner<'a, K, (), A>,
+    inner: ExtractIfInner<'a, K, (), A>,
 }
 
 /// A lazy iterator producing elements in the intersection of `HashSet`s.
@@ -1748,21 +1771,7 @@ impl<K: fmt::Debug, A: Allocator + Clone> fmt::Debug for Drain<'_, K, A> {
     }
 }
 
-impl<'a, K, F, A: Allocator + Clone> Drop for DrainFilter<'a, K, F, A>
-where
-    F: FnMut(&K) -> bool,
-{
-    #[cfg_attr(feature = "inline-more", inline)]
-    fn drop(&mut self) {
-        while let Some(item) = self.next() {
-            let guard = ConsumeAllOnDrop(self);
-            drop(item);
-            mem::forget(guard);
-        }
-    }
-}
-
-impl<K, F, A: Allocator + Clone> Iterator for DrainFilter<'_, K, F, A>
+impl<K, F, A: Allocator + Clone> Iterator for ExtractIf<'_, K, F, A>
 where
     F: FnMut(&K) -> bool,
 {
@@ -1781,10 +1790,7 @@ where
     }
 }
 
-impl<K, F, A: Allocator + Clone> FusedIterator for DrainFilter<'_, K, F, A> where
-    F: FnMut(&K) -> bool
-{
-}
+impl<K, F, A: Allocator + Clone> FusedIterator for ExtractIf<'_, K, F, A> where F: FnMut(&K) -> bool {}
 
 impl<T, S, A: Allocator + Clone> Clone for Intersection<'_, T, S, A> {
     #[cfg_attr(feature = "inline-more", inline)]
@@ -2712,10 +2718,10 @@ mod test_set {
         set.insert(1);
         set.insert(2);
 
-        let set_str = format!("{:?}", set);
+        let set_str = format!("{set:?}");
 
         assert!(set_str == "{1, 2}" || set_str == "{2, 1}");
-        assert_eq!(format!("{:?}", empty), "{}");
+        assert_eq!(format!("{empty:?}"), "{}");
     }
 
     #[test]
@@ -2790,6 +2796,7 @@ mod test_set {
     }
 
     #[test]
+    #[allow(clippy::needless_borrow)]
     fn test_extend_ref() {
         let mut a = HashSet::new();
         a.insert(1);
@@ -2829,10 +2836,10 @@ mod test_set {
     }
 
     #[test]
-    fn test_drain_filter() {
+    fn test_extract_if() {
         {
             let mut set: HashSet<i32> = (0..8).collect();
-            let drained = set.drain_filter(|&k| k % 2 == 0);
+            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);
@@ -2840,7 +2847,7 @@ mod test_set {
         }
         {
             let mut set: HashSet<i32> = (0..8).collect();
-            drop(set.drain_filter(|&k| k % 2 == 0));
+            set.extract_if(|&k| k % 2 == 0).for_each(drop);
             assert_eq!(set.len(), 4, "Removes non-matching items on drop");
         }
     }
@@ -2886,4 +2893,11 @@ mod test_set {
             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();
+    }
 }