Merge from rust-lang/rust

1 files changed, 20 insertions, 16 deletions

diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index c36b8f6a1ac..2c0d19b0ada 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -9,13 +9,10 @@
 //! `#[cfg(target_has_atomic = "ptr")]`.
 
 use core::any::Any;
-use core::borrow;
 #[cfg(not(no_global_oom_handling))]
 use core::clone::CloneToUninit;
 use core::cmp::Ordering;
-use core::fmt;
 use core::hash::{Hash, Hasher};
-use core::hint;
 use core::intrinsics::abort;
 #[cfg(not(no_global_oom_handling))]
 use core::iter;
@@ -23,12 +20,13 @@ use core::marker::{PhantomData, Unsize};
 use core::mem::{self, align_of_val_raw, ManuallyDrop};
 use core::ops::{CoerceUnsized, Deref, DerefPure, DispatchFromDyn, Receiver};
 use core::panic::{RefUnwindSafe, UnwindSafe};
-use core::pin::Pin;
+use core::pin::{Pin, PinCoerceUnsized};
 use core::ptr::{self, NonNull};
 #[cfg(not(no_global_oom_handling))]
 use core::slice::from_raw_parts_mut;
 use core::sync::atomic;
 use core::sync::atomic::Ordering::{Acquire, Relaxed, Release};
+use core::{borrow, fmt, hint};
 
 #[cfg(not(no_global_oom_handling))]
 use crate::alloc::handle_alloc_error;
@@ -428,7 +426,7 @@ impl<T> Arc<T> {
     /// }
     ///
     /// impl Gadget {
-    ///     /// Construct a reference counted Gadget.
+    ///     /// Constructs a reference counted Gadget.
     ///     fn new() -> Arc<Self> {
     ///         // `me` is a `Weak<Gadget>` pointing at the new allocation of the
     ///         // `Arc` we're constructing.
@@ -438,7 +436,7 @@ impl<T> Arc<T> {
     ///         })
     ///     }
     ///
-    ///     /// Return a reference counted pointer to Self.
+    ///     /// Returns a reference counted pointer to Self.
     ///     fn me(&self) -> Arc<Self> {
     ///         self.me.upgrade().unwrap()
     ///     }
@@ -2144,6 +2142,12 @@ impl<T: ?Sized, A: Allocator> Deref for Arc<T, A> {
     }
 }
 
+#[unstable(feature = "pin_coerce_unsized_trait", issue = "123430")]
+unsafe impl<T: ?Sized, A: Allocator> PinCoerceUnsized for Arc<T, A> {}
+
+#[unstable(feature = "pin_coerce_unsized_trait", issue = "123430")]
+unsafe impl<T: ?Sized, A: Allocator> PinCoerceUnsized for Weak<T, A> {}
+
 #[unstable(feature = "deref_pure_trait", issue = "87121")]
 unsafe impl<T: ?Sized, A: Allocator> DerefPure for Arc<T, A> {}
 
@@ -2531,7 +2535,7 @@ unsafe impl<#[may_dangle] T: ?Sized, A: Allocator> Drop for Arc<T, A> {
 }
 
 impl<A: Allocator> Arc<dyn Any + Send + Sync, A> {
-    /// Attempt to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type.
+    /// Attempts to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type.
     ///
     /// # Examples
     ///
@@ -3545,7 +3549,7 @@ impl<T, const N: usize> From<[T; N]> for Arc<[T]> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T: Clone> From<&[T]> for Arc<[T]> {
-    /// Allocate a reference-counted slice and fill it by cloning `v`'s items.
+    /// Allocates a reference-counted slice and fills it by cloning `v`'s items.
     ///
     /// # Example
     ///
@@ -3564,7 +3568,7 @@ impl<T: Clone> From<&[T]> for Arc<[T]> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<&str> for Arc<str> {
-    /// Allocate a reference-counted `str` and copy `v` into it.
+    /// Allocates a reference-counted `str` and copies `v` into it.
     ///
     /// # Example
     ///
@@ -3583,7 +3587,7 @@ impl From<&str> for Arc<str> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl From<String> for Arc<str> {
-    /// Allocate a reference-counted `str` and copy `v` into it.
+    /// Allocates a reference-counted `str` and copies `v` into it.
     ///
     /// # Example
     ///
@@ -3621,7 +3625,7 @@ impl<T: ?Sized, A: Allocator> From<Box<T, A>> for Arc<T, A> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "shared_from_slice", since = "1.21.0")]
 impl<T, A: Allocator + Clone> From<Vec<T, A>> for Arc<[T], A> {
-    /// Allocate a reference-counted slice and move `v`'s items into it.
+    /// Allocates a reference-counted slice and moves `v`'s items into it.
     ///
     /// # Example
     ///
@@ -3654,8 +3658,8 @@ where
     B: ToOwned + ?Sized,
     Arc<B>: From<&'a B> + From<B::Owned>,
 {
-    /// Create an atomically reference-counted pointer from
-    /// a clone-on-write pointer by copying its content.
+    /// Creates an atomically reference-counted pointer from a clone-on-write
+    /// pointer by copying its content.
     ///
     /// # Example
     ///
@@ -3811,7 +3815,7 @@ impl<T: ?Sized, A: Allocator> AsRef<T> for Arc<T, A> {
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized, A: Allocator> Unpin for Arc<T, A> {}
 
-/// Get the offset within an `ArcInner` for the payload behind a pointer.
+/// Gets the offset within an `ArcInner` for the payload behind a pointer.
 ///
 /// # Safety
 ///
@@ -3833,7 +3837,7 @@ fn data_offset_align(align: usize) -> usize {
     layout.size() + layout.padding_needed_for(align)
 }
 
-/// A unique owning pointer to a [`ArcInner`] **that does not imply the contents are initialized,**
+/// A unique owning pointer to an [`ArcInner`] **that does not imply the contents are initialized,**
 /// but will deallocate it (without dropping the value) when dropped.
 ///
 /// This is a helper for [`Arc::make_mut()`] to ensure correct cleanup on panic.
@@ -3846,7 +3850,7 @@ struct UniqueArcUninit<T: ?Sized, A: Allocator> {
 
 #[cfg(not(no_global_oom_handling))]
 impl<T: ?Sized, A: Allocator> UniqueArcUninit<T, A> {
-    /// Allocate a ArcInner with layout suitable to contain `for_value` or a clone of it.
+    /// Allocates an ArcInner with layout suitable to contain `for_value` or a clone of it.
     fn new(for_value: &T, alloc: A) -> UniqueArcUninit<T, A> {
         let layout = Layout::for_value(for_value);
         let ptr = unsafe {