Auto merge of #31042 - shahn:weak_annotations, r=alexcrichton

This was accidentally introduced in
7e2ffc7.

Author: bors

src/liballoc/rc.rs

@@ -715,9 +715,9 @@ pub struct Weak<T: ?Sized> {
     _ptr: Shared<RcBox<T>>,
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "rc_weak", since = "1.4.0")]
 impl<T: ?Sized> !marker::Send for Weak<T> {}
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "rc_weak", since = "1.4.0")]
 impl<T: ?Sized> !marker::Sync for Weak<T> {}
 
 #[unstable(feature = "coerce_unsized", issue = "27732")]
@@ -753,7 +753,7 @@ impl<T: ?Sized> Weak<T> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "rc_weak", since = "1.4.0")]
 impl<T: ?Sized> Drop for Weak<T> {
     /// Drops the `Weak<T>`.
     ///
@@ -819,7 +819,7 @@ impl<T: ?Sized> Clone for Weak<T> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "rc_weak", since = "1.4.0")]
 impl<T: ?Sized + fmt::Debug> fmt::Debug for Weak<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "(Weak)")