Rollup merge of #161429 - maxdexh:allocator-arc-sync-send, r=nia-e

Tighten allocator `Send`/`Sync` requirements for `Arc` in preparation for refactor

Fixes some of the changes from #161115 to the `Send` and `Sync` bounds on the allocator in `Arc`, so that we can move the allocator inside `ArcInner` later, like we plan to once the ongoing work (#132553) on it has been completed.

r? nia-e

Author: jhpratt

library/alloc/src/rc.rs

@@ -344,10 +344,7 @@ impl<T: ?Sized, A: Allocator> !Sync for Rc<T, A> {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: RefUnwindSafe + ?Sized, A: Allocator + UnwindSafe + RefUnwindSafe> UnwindSafe for Rc<T, A> {}
 #[stable(feature = "rc_ref_unwind_safe", since = "1.58.0")]
-impl<T: RefUnwindSafe + ?Sized, A: Allocator + UnwindSafe + RefUnwindSafe> RefUnwindSafe
-    for Rc<T, A>
-{
-}
+impl<T: RefUnwindSafe + ?Sized, A: Allocator + RefUnwindSafe> RefUnwindSafe for Rc<T, A> {}
 
 #[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Rc<U, A>> for Rc<T, A> {}

library/alloc/src/sync.rs

@@ -283,7 +283,7 @@ pub struct Arc<
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Send for Arc<T, A> {}
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Sync> Sync for Arc<T, A> {}
+unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Sync for Arc<T, A> {}
 
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: RefUnwindSafe + ?Sized, A: Allocator + UnwindSafe + RefUnwindSafe> UnwindSafe
@@ -369,7 +369,7 @@ pub struct Weak<
 #[stable(feature = "arc_weak", since = "1.4.0")]
 unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Send for Weak<T, A> {}
 #[stable(feature = "arc_weak", since = "1.4.0")]
-unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Sync> Sync for Weak<T, A> {}
+unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Sync for Weak<T, A> {}
 
 #[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Weak<U, A>> for Weak<T, A> {}
@@ -4429,7 +4429,7 @@ pub struct UniqueArc<
 unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Send for UniqueArc<T, A> {}
 
 #[unstable(feature = "unique_rc_arc", issue = "112566")]
-unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Sync> Sync for UniqueArc<T, A> {}
+unsafe impl<T: ?Sized + Sync + Send, A: Allocator + Send + Sync> Sync for UniqueArc<T, A> {}
 
 #[unstable(feature = "unique_rc_arc", issue = "112566")]
 // #[unstable(feature = "coerce_unsized", issue = "18598")]