Merging upstream version 1.72.1+dfsg1.

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

4 files changed, 103 insertions, 78 deletions

diff --git a/library/std/src/collections/hash/map.rs b/library/std/src/collections/hash/map.rs
index c722bad2e..a083b6560 100644
--- a/library/std/src/collections/hash/map.rs
+++ b/library/std/src/collections/hash/map.rs
@@ -623,28 +623,27 @@ impl<K, V, S> HashMap<K, V, S> {
     /// If the closure returns false, or panics, the element remains in the map and will not be
     /// yielded.
     ///
-    /// 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.
     ///
-    /// If the iterator is only partially consumed or not consumed at all, each of the remaining
-    /// elements will still be subjected to the closure and removed and dropped if it returns true.
+    /// 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.
     ///
-    /// 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.
+    /// [`retain`]: HashMap::retain
     ///
     /// # Examples
     ///
     /// Splitting a map into even and odd keys, reusing the original map:
     ///
     /// ```
-    /// #![feature(hash_drain_filter)]
+    /// #![feature(hash_extract_if)]
     /// use std::collections::HashMap;
     ///
     /// 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 extracted: HashMap<i32, i32> = map.extract_if(|k, _v| k % 2 == 0).collect();
     ///
-    /// let mut evens = drained.keys().copied().collect::<Vec<_>>();
+    /// let mut evens = extracted.keys().copied().collect::<Vec<_>>();
     /// let mut odds = map.keys().copied().collect::<Vec<_>>();
     /// evens.sort();
     /// odds.sort();
@@ -654,12 +653,12 @@ impl<K, V, S> HashMap<K, V, S> {
     /// ```
     #[inline]
     #[rustc_lint_query_instability]
-    #[unstable(feature = "hash_drain_filter", issue = "59618")]
-    pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, K, V, F>
+    #[unstable(feature = "hash_extract_if", issue = "59618")]
+    pub fn extract_if<F>(&mut self, pred: F) -> ExtractIf<'_, K, V, F>
     where
         F: FnMut(&K, &mut V) -> bool,
     {
-        DrainFilter { base: self.base.drain_filter(pred) }
+        ExtractIf { base: self.base.extract_if(pred) }
     }
 
     /// Retains only the elements specified by the predicate.
@@ -1578,28 +1577,29 @@ impl<'a, K, V> Drain<'a, K, V> {
 
 /// A draining, filtering iterator over the entries of a `HashMap`.
 ///
-/// This `struct` is created by the [`drain_filter`] method on [`HashMap`].
+/// This `struct` is created by the [`extract_if`] method on [`HashMap`].
 ///
-/// [`drain_filter`]: HashMap::drain_filter
+/// [`extract_if`]: HashMap::extract_if
 ///
 /// # Example
 ///
 /// ```
-/// #![feature(hash_drain_filter)]
+/// #![feature(hash_extract_if)]
 ///
 /// use std::collections::HashMap;
 ///
 /// let mut map = HashMap::from([
 ///     ("a", 1),
 /// ]);
-/// let iter = map.drain_filter(|_k, v| *v % 2 == 0);
+/// let iter = map.extract_if(|_k, v| *v % 2 == 0);
 /// ```
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-pub struct DrainFilter<'a, K, V, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+pub struct ExtractIf<'a, K, V, F>
 where
     F: FnMut(&K, &mut V) -> bool,
 {
-    base: base::DrainFilter<'a, K, V, F>,
+    base: base::ExtractIf<'a, K, V, F>,
 }
 
 /// A mutable iterator over the values of a `HashMap`.
@@ -2479,8 +2479,8 @@ where
     }
 }
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<K, V, F> Iterator for DrainFilter<'_, K, V, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<K, V, F> Iterator for ExtractIf<'_, K, V, F>
 where
     F: FnMut(&K, &mut V) -> bool,
 {
@@ -2496,16 +2496,16 @@ where
     }
 }
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<K, V, F> FusedIterator for DrainFilter<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<K, V, F> FusedIterator for ExtractIf<'_, K, V, F> where F: FnMut(&K, &mut V) -> bool {}
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<'a, K, V, F> fmt::Debug for DrainFilter<'a, K, V, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<'a, K, V, F> fmt::Debug for ExtractIf<'a, K, V, F>
 where
     F: FnMut(&K, &mut V) -> bool,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("DrainFilter").finish_non_exhaustive()
+        f.debug_struct("ExtractIf").finish_non_exhaustive()
     }
 }
 
@@ -2543,12 +2543,12 @@ impl<'a, K, V> Entry<'a, K, V> {
     /// ```
     /// use std::collections::HashMap;
     ///
-    /// let mut map: HashMap<&str, String> = HashMap::new();
-    /// let s = "hoho".to_string();
+    /// let mut map = HashMap::new();
+    /// let value = "hoho";
     ///
-    /// map.entry("poneyland").or_insert_with(|| s);
+    /// map.entry("poneyland").or_insert_with(|| value);
     ///
-    /// assert_eq!(map["poneyland"], "hoho".to_string());
+    /// assert_eq!(map["poneyland"], "hoho");
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/collections/hash/map/tests.rs b/library/std/src/collections/hash/map/tests.rs
index 6b89518e2..91a3776e7 100644
--- a/library/std/src/collections/hash/map/tests.rs
+++ b/library/std/src/collections/hash/map/tests.rs
@@ -944,7 +944,7 @@ fn test_raw_entry() {
     }
 }
 
-mod test_drain_filter {
+mod test_extract_if {
     use super::*;
 
     use crate::panic::{catch_unwind, AssertUnwindSafe};
@@ -968,7 +968,7 @@ mod test_drain_filter {
     #[test]
     fn empty() {
         let mut map: HashMap<i32, i32> = HashMap::new();
-        map.drain_filter(|_, _| unreachable!("there's nothing to decide on"));
+        map.extract_if(|_, _| unreachable!("there's nothing to decide on")).for_each(drop);
         assert!(map.is_empty());
     }
 
@@ -976,7 +976,7 @@ mod test_drain_filter {
     fn consuming_nothing() {
         let pairs = (0..3).map(|i| (i, i));
         let mut map: HashMap<_, _> = pairs.collect();
-        assert!(map.drain_filter(|_, _| false).eq_sorted(crate::iter::empty()));
+        assert!(map.extract_if(|_, _| false).eq_sorted(crate::iter::empty()));
         assert_eq!(map.len(), 3);
     }
 
@@ -984,7 +984,7 @@ mod test_drain_filter {
     fn consuming_all() {
         let pairs = (0..3).map(|i| (i, i));
         let mut map: HashMap<_, _> = pairs.clone().collect();
-        assert!(map.drain_filter(|_, _| true).eq_sorted(pairs));
+        assert!(map.extract_if(|_, _| true).eq_sorted(pairs));
         assert!(map.is_empty());
     }
 
@@ -993,7 +993,7 @@ mod test_drain_filter {
         let pairs = (0..3).map(|i| (i, i));
         let mut map: HashMap<_, _> = pairs.collect();
         assert!(
-            map.drain_filter(|_, v| {
+            map.extract_if(|_, v| {
                 *v += 6;
                 false
             })
@@ -1008,7 +1008,7 @@ mod test_drain_filter {
         let pairs = (0..3).map(|i| (i, i));
         let mut map: HashMap<_, _> = pairs.collect();
         assert!(
-            map.drain_filter(|_, v| {
+            map.extract_if(|_, v| {
                 *v += 6;
                 true
             })
@@ -1034,14 +1034,15 @@ mod test_drain_filter {
         let mut map = (0..3).map(|i| (i, D)).collect::<HashMap<_, _>>();
 
         catch_unwind(move || {
-            drop(map.drain_filter(|_, _| {
+            map.extract_if(|_, _| {
                 PREDS.fetch_add(1, Ordering::SeqCst);
                 true
-            }))
+            })
+            .for_each(drop)
         })
         .unwrap_err();
 
-        assert_eq!(PREDS.load(Ordering::SeqCst), 3);
+        assert_eq!(PREDS.load(Ordering::SeqCst), 2);
         assert_eq!(DROPS.load(Ordering::SeqCst), 3);
     }
 
@@ -1060,10 +1061,11 @@ mod test_drain_filter {
         let mut map = (0..3).map(|i| (i, D)).collect::<HashMap<_, _>>();
 
         catch_unwind(AssertUnwindSafe(|| {
-            drop(map.drain_filter(|_, _| match PREDS.fetch_add(1, Ordering::SeqCst) {
+            map.extract_if(|_, _| match PREDS.fetch_add(1, Ordering::SeqCst) {
                 0 => true,
                 _ => panic!(),
-            }))
+            })
+            .for_each(drop)
         }))
         .unwrap_err();
 
@@ -1088,7 +1090,7 @@ mod test_drain_filter {
         let mut map = (0..3).map(|i| (i, D)).collect::<HashMap<_, _>>();
 
         {
-            let mut it = map.drain_filter(|_, _| match PREDS.fetch_add(1, Ordering::SeqCst) {
+            let mut it = map.extract_if(|_, _| match PREDS.fetch_add(1, Ordering::SeqCst) {
                 0 => true,
                 _ => panic!(),
             });
diff --git a/library/std/src/collections/hash/set.rs b/library/std/src/collections/hash/set.rs
index ac906e682..ec59634df 100644
--- a/library/std/src/collections/hash/set.rs
+++ b/library/std/src/collections/hash/set.rs
@@ -262,25 +262,24 @@ impl<T, S> HashSet<T, S> {
     /// If the closure returns false, the value will remain in the list and will not be yielded
     /// by the iterator.
     ///
-    /// If the iterator is only partially consumed or not consumed at all, each of the remaining
-    /// values will still be subjected to the closure and removed and dropped if it returns true.
+    /// 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.
     ///
-    /// It is unspecified how many more values will be subjected to the closure
-    /// if a panic occurs in the closure, or if a panic occurs while dropping a value, or if the
-    /// `DrainFilter` itself is leaked.
+    /// [`retain`]: HashSet::retain
     ///
     /// # Examples
     ///
     /// Splitting a set into even and odd values, reusing the original set:
     ///
     /// ```
-    /// #![feature(hash_drain_filter)]
+    /// #![feature(hash_extract_if)]
     /// use std::collections::HashSet;
     ///
     /// let mut set: HashSet<i32> = (0..8).collect();
-    /// let drained: HashSet<i32> = set.drain_filter(|v| v % 2 == 0).collect();
+    /// let extracted: HashSet<i32> = set.extract_if(|v| v % 2 == 0).collect();
     ///
-    /// let mut evens = drained.into_iter().collect::<Vec<_>>();
+    /// let mut evens = extracted.into_iter().collect::<Vec<_>>();
     /// let mut odds = set.into_iter().collect::<Vec<_>>();
     /// evens.sort();
     /// odds.sort();
@@ -290,12 +289,12 @@ impl<T, S> HashSet<T, S> {
     /// ```
     #[inline]
     #[rustc_lint_query_instability]
-    #[unstable(feature = "hash_drain_filter", issue = "59618")]
-    pub fn drain_filter<F>(&mut self, pred: F) -> DrainFilter<'_, T, F>
+    #[unstable(feature = "hash_extract_if", issue = "59618")]
+    pub fn extract_if<F>(&mut self, pred: F) -> ExtractIf<'_, T, F>
     where
         F: FnMut(&T) -> bool,
     {
-        DrainFilter { base: self.base.drain_filter(pred) }
+        ExtractIf { base: self.base.extract_if(pred) }
     }
 
     /// Retains only the elements specified by the predicate.
@@ -868,7 +867,9 @@ where
     /// Returns whether the value was newly inserted. That is:
     ///
     /// - If the set did not previously contain this value, `true` is returned.
-    /// - If the set already contained this value, `false` is returned.
+    /// - If the set already contained this value, `false` is returned,
+    ///   and the set is not modified: original value is not replaced,
+    ///   and the value passed as argument is dropped.
     ///
     /// # Examples
     ///
@@ -1310,27 +1311,27 @@ pub struct Drain<'a, K: 'a> {
 
 /// A draining, filtering iterator over the items of a `HashSet`.
 ///
-/// This `struct` is created by the [`drain_filter`] method on [`HashSet`].
+/// This `struct` is created by the [`extract_if`] method on [`HashSet`].
 ///
-/// [`drain_filter`]: HashSet::drain_filter
+/// [`extract_if`]: HashSet::extract_if
 ///
 /// # Examples
 ///
 /// ```
-/// #![feature(hash_drain_filter)]
+/// #![feature(hash_extract_if)]
 ///
 /// use std::collections::HashSet;
 ///
 /// let mut a = HashSet::from([1, 2, 3]);
 ///
-/// let mut drain_filtered = a.drain_filter(|v| v % 2 == 0);
+/// let mut extract_ifed = a.extract_if(|v| v % 2 == 0);
 /// ```
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-pub struct DrainFilter<'a, K, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+pub struct ExtractIf<'a, K, F>
 where
     F: FnMut(&K) -> bool,
 {
-    base: base::DrainFilter<'a, K, F>,
+    base: base::ExtractIf<'a, K, F>,
 }
 
 /// A lazy iterator producing elements in the intersection of `HashSet`s.
@@ -1576,8 +1577,8 @@ impl<K: fmt::Debug> fmt::Debug for Drain<'_, K> {
     }
 }
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<K, F> Iterator for DrainFilter<'_, K, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<K, F> Iterator for ExtractIf<'_, K, F>
 where
     F: FnMut(&K) -> bool,
 {
@@ -1593,16 +1594,16 @@ where
     }
 }
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<K, F> FusedIterator for DrainFilter<'_, K, F> where F: FnMut(&K) -> bool {}
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<K, F> FusedIterator for ExtractIf<'_, K, F> where F: FnMut(&K) -> bool {}
 
-#[unstable(feature = "hash_drain_filter", issue = "59618")]
-impl<'a, K, F> fmt::Debug for DrainFilter<'a, K, F>
+#[unstable(feature = "hash_extract_if", issue = "59618")]
+impl<'a, K, F> fmt::Debug for ExtractIf<'a, K, F>
 where
     F: FnMut(&K) -> bool,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("DrainFilter").finish_non_exhaustive()
+        f.debug_struct("ExtractIf").finish_non_exhaustive()
     }
 }
 
diff --git a/library/std/src/collections/hash/set/tests.rs b/library/std/src/collections/hash/set/tests.rs
index 941a0450c..e0cd80b44 100644
--- a/library/std/src/collections/hash/set/tests.rs
+++ b/library/std/src/collections/hash/set/tests.rs
@@ -3,6 +3,7 @@ use super::HashSet;
 
 use crate::panic::{catch_unwind, AssertUnwindSafe};
 use crate::sync::atomic::{AtomicU32, Ordering};
+use crate::sync::Arc;
 
 #[test]
 fn test_zero_capacities() {
@@ -418,18 +419,18 @@ fn test_retain() {
 }
 
 #[test]
-fn test_drain_filter() {
+fn test_extract_if() {
     let mut x: HashSet<_> = [1].iter().copied().collect();
     let mut y: HashSet<_> = [1].iter().copied().collect();
 
-    x.drain_filter(|_| true);
-    y.drain_filter(|_| false);
+    x.extract_if(|_| true).for_each(drop);
+    y.extract_if(|_| false).for_each(drop);
     assert_eq!(x.len(), 0);
     assert_eq!(y.len(), 1);
 }
 
 #[test]
-fn test_drain_filter_drop_panic_leak() {
+fn test_extract_if_drop_panic_leak() {
     static PREDS: AtomicU32 = AtomicU32::new(0);
     static DROPS: AtomicU32 = AtomicU32::new(0);
 
@@ -446,19 +447,20 @@ fn test_drain_filter_drop_panic_leak() {
     let mut set = (0..3).map(|i| D(i)).collect::<HashSet<_>>();
 
     catch_unwind(move || {
-        drop(set.drain_filter(|_| {
+        set.extract_if(|_| {
             PREDS.fetch_add(1, Ordering::SeqCst);
             true
-        }))
+        })
+        .for_each(drop)
     })
     .ok();
 
-    assert_eq!(PREDS.load(Ordering::SeqCst), 3);
+    assert_eq!(PREDS.load(Ordering::SeqCst), 2);
     assert_eq!(DROPS.load(Ordering::SeqCst), 3);
 }
 
 #[test]
-fn test_drain_filter_pred_panic_leak() {
+fn test_extract_if_pred_panic_leak() {
     static PREDS: AtomicU32 = AtomicU32::new(0);
     static DROPS: AtomicU32 = AtomicU32::new(0);
 
@@ -473,10 +475,11 @@ fn test_drain_filter_pred_panic_leak() {
     let mut set: HashSet<_> = (0..3).map(|_| D).collect();
 
     catch_unwind(AssertUnwindSafe(|| {
-        drop(set.drain_filter(|_| match PREDS.fetch_add(1, Ordering::SeqCst) {
+        set.extract_if(|_| match PREDS.fetch_add(1, Ordering::SeqCst) {
             0 => true,
             _ => panic!(),
-        }))
+        })
+        .for_each(drop)
     }))
     .ok();
 
@@ -502,3 +505,22 @@ fn const_with_hasher() {
     const X: HashSet<(), ()> = HashSet::with_hasher(());
     assert_eq!(X.len(), 0);
 }
+
+#[test]
+fn test_insert_does_not_overwrite_the_value() {
+    let first_value = Arc::new(17);
+    let second_value = Arc::new(17);
+
+    let mut set = HashSet::new();
+    let inserted = set.insert(first_value.clone());
+    assert!(inserted);
+
+    let inserted = set.insert(second_value);
+    assert!(!inserted);
+
+    assert!(
+        Arc::ptr_eq(set.iter().next().unwrap(), &first_value),
+        "Insert must not overwrite the value, so the contained value pointer \
+            must be the same as first value pointer we inserted"
+    );
+}