Merge from rustc

9 files changed, 77 insertions, 5 deletions

diff --git a/library/alloc/Cargo.toml b/library/alloc/Cargo.toml
index 3464047d4ee..07596fa16f9 100644
--- a/library/alloc/Cargo.toml
+++ b/library/alloc/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2021"
 
 [dependencies]
 core = { path = "../core" }
-compiler_builtins = { version = "=0.1.138", features = ['rustc-dep-of-std'] }
+compiler_builtins = { version = "=0.1.140", features = ['rustc-dep-of-std'] }
 
 [dev-dependencies]
 rand = { version = "0.8.5", default-features = false, features = ["alloc"] }
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 23b85fbd4eb..ca3bd24a420 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -761,6 +761,26 @@ impl<T> Box<[T]> {
         };
         unsafe { Ok(RawVec::from_raw_parts_in(ptr.as_ptr(), len, Global).into_box(len)) }
     }
+
+    /// Converts the boxed slice into a boxed array.
+    ///
+    /// This operation does not reallocate; the underlying array of the slice is simply reinterpreted as an array type.
+    ///
+    /// If `N` is not exactly equal to the length of `self`, then this method returns `None`.
+    #[unstable(feature = "slice_as_array", issue = "133508")]
+    #[inline]
+    #[must_use]
+    pub fn into_array<const N: usize>(self) -> Option<Box<[T; N]>> {
+        if self.len() == N {
+            let ptr = Self::into_raw(self) as *mut [T; N];
+
+            // SAFETY: The underlying array of a slice has the exact same layout as an actual array `[T; N]` if `N` is equal to the slice's length.
+            let me = unsafe { Box::from_raw(ptr) };
+            Some(me)
+        } else {
+            None
+        }
+    }
 }
 
 impl<T, A: Allocator> Box<[T], A> {
diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
index d1ce4e215ed..6d305386dbf 100644
--- a/library/alloc/src/collections/btree/map.rs
+++ b/library/alloc/src/collections/btree/map.rs
@@ -2289,6 +2289,10 @@ impl<K, V> FusedIterator for RangeMut<'_, K, V> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
+    /// Constructs a `BTreeMap<K, V>` from an iterator of key-value pairs.
+    ///
+    /// If the iterator produces any pairs with equal keys,
+    /// all but one of the corresponding values will be dropped.
     fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> BTreeMap<K, V> {
         let mut inputs: Vec<_> = iter.into_iter().collect();
 
@@ -2403,7 +2407,10 @@ where
 
 #[stable(feature = "std_collections_from_array", since = "1.56.0")]
 impl<K: Ord, V, const N: usize> From<[(K, V); N]> for BTreeMap<K, V> {
-    /// Converts a `[(K, V); N]` into a `BTreeMap<(K, V)>`.
+    /// Converts a `[(K, V); N]` into a `BTreeMap<K, V>`.
+    ///
+    /// If any entries in the array have equal keys,
+    /// all but one of the corresponding values will be dropped.
     ///
     /// ```
     /// use std::collections::BTreeMap;
diff --git a/library/alloc/src/collections/btree/set.rs b/library/alloc/src/collections/btree/set.rs
index 6f8c3b2d152..9660023d694 100644
--- a/library/alloc/src/collections/btree/set.rs
+++ b/library/alloc/src/collections/btree/set.rs
@@ -1491,6 +1491,11 @@ impl<T: Ord, A: Allocator + Clone> BTreeSet<T, A> {
 impl<T: Ord, const N: usize> From<[T; N]> for BTreeSet<T> {
     /// Converts a `[T; N]` into a `BTreeSet<T>`.
     ///
+    /// If the array contains any equal values,
+    /// all but one will be dropped.
+    ///
+    /// # Examples
+    ///
     /// ```
     /// use std::collections::BTreeSet;
     ///
diff --git a/library/alloc/src/ffi/mod.rs b/library/alloc/src/ffi/mod.rs
index 4f9dc40a3cf..695d7ad07cf 100644
--- a/library/alloc/src/ffi/mod.rs
+++ b/library/alloc/src/ffi/mod.rs
@@ -83,7 +83,7 @@
 #[doc(inline)]
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::CString;
-#[doc(no_inline)]
+#[doc(inline)]
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::{FromVecWithNulError, IntoStringError, NulError};
 
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index 2c7cdcf0cfb..e93ff2f9023 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -420,7 +420,7 @@ impl<A: Allocator> RawVecInner<A> {
         match Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc, elem_layout) {
             Ok(this) => {
                 unsafe {
-                    // Make it more obvious that a subsquent Vec::reserve(capacity) will not allocate.
+                    // Make it more obvious that a subsequent Vec::reserve(capacity) will not allocate.
                     hint::assert_unchecked(!this.needs_to_grow(0, capacity, elem_layout));
                 }
                 this
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index b7ec3af9818..e014404eff3 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -1084,6 +1084,26 @@ impl<T> Rc<[T]> {
             ))
         }
     }
+
+    /// Converts the reference-counted slice into a reference-counted array.
+    ///
+    /// This operation does not reallocate; the underlying array of the slice is simply reinterpreted as an array type.
+    ///
+    /// If `N` is not exactly equal to the length of `self`, then this method returns `None`.
+    #[unstable(feature = "slice_as_array", issue = "133508")]
+    #[inline]
+    #[must_use]
+    pub fn into_array<const N: usize>(self) -> Option<Rc<[T; N]>> {
+        if self.len() == N {
+            let ptr = Self::into_raw(self) as *const [T; N];
+
+            // SAFETY: The underlying array of a slice has the exact same layout as an actual array `[T; N]` if `N` is equal to the slice's length.
+            let me = unsafe { Rc::from_raw(ptr) };
+            Some(me)
+        } else {
+            None
+        }
+    }
 }
 
 impl<T, A: Allocator> Rc<[T], A> {
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 9be0b3e3e88..b34a6d3f660 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -1203,6 +1203,26 @@ impl<T> Arc<[T]> {
             ))
         }
     }
+
+    /// Converts the reference-counted slice into a reference-counted array.
+    ///
+    /// This operation does not reallocate; the underlying array of the slice is simply reinterpreted as an array type.
+    ///
+    /// If `N` is not exactly equal to the length of `self`, then this method returns `None`.
+    #[unstable(feature = "slice_as_array", issue = "133508")]
+    #[inline]
+    #[must_use]
+    pub fn into_array<const N: usize>(self) -> Option<Arc<[T; N]>> {
+        if self.len() == N {
+            let ptr = Self::into_raw(self) as *const [T; N];
+
+            // SAFETY: The underlying array of a slice has the exact same layout as an actual array `[T; N]` if `N` is equal to the slice's length.
+            let me = unsafe { Arc::from_raw(ptr) };
+            Some(me)
+        } else {
+            None
+        }
+    }
 }
 
 impl<T, A: Allocator> Arc<[T], A> {
diff --git a/library/alloc/tests/sort/tests.rs b/library/alloc/tests/sort/tests.rs
index 14e6013f965..4cc79010e8f 100644
--- a/library/alloc/tests/sort/tests.rs
+++ b/library/alloc/tests/sort/tests.rs
@@ -33,7 +33,7 @@ fn check_is_sorted<T: Ord + Clone + Debug, S: Sort>(v: &mut [T]) {
             known_good_stable_sort::sort(known_good_sorted_vec.as_mut_slice());
 
             if is_small_test {
-                eprintln!("Orginal:  {:?}", v_orig);
+                eprintln!("Original: {:?}", v_orig);
                 eprintln!("Expected: {:?}", known_good_sorted_vec);
                 eprintln!("Got:      {:?}", v);
             } else {