remove the T: Sync requirement for RwLock<T>: Send

oconnor663 · oconnor663 · commit fbf6885fd3eb · 2017-10-13T18:54:49.000-04:00
That requirement makes sense for containers like `Arc` that don't uniquely own their contents, but `RwLock` is not one of those. This restriction was added in 380d23b, but it's not clear why.
diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
@@ -82,7 +82,7 @@ pub struct RwLock<T: ?Sized> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: ?Sized + Send + Sync> Send for RwLock<T> {}
+unsafe impl<T: ?Sized + Send> Send for RwLock<T> {}
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
 

Original file line number	Diff line number	Diff line change
`@@ -82,7 +82,7 @@ pub struct RwLock<T: ?Sized> {`
`82`	`82`	`}`
`83`	`83`
`84`	`84`	`#[stable(feature = "rust1", since = "1.0.0")]`
`85`		`-unsafe impl<T: ?Sized + Send + Sync> Send for RwLock<T> {}`
	`85`	`+unsafe impl<T: ?Sized + Send> Send for RwLock<T> {}`
`86`	`86`	`#[stable(feature = "rust1", since = "1.0.0")]`
`87`	`87`	`unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}`
`88`	`88`