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

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
https://github.com/rust-lang/rust/commit/380d23b5d4b9fb8f5f0ebf178590f61528b2483e,
but it's not clear why.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
index 5c49d6b5845..5555f364e6e 100644
--- 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> {}