From ad73330391d7b608e6650cb83dc76d5eeb1919ed Mon Sep 17 00:00:00 2001 From: Jonathan Reem Date: Fri, 5 Feb 2016 17:11:17 -0800 Subject: [PATCH] Fix RwLock*Guard::map to not allow escaping a reference to the data. Also update the instability reason to include a note about a possible bad interaction with condition variables on systems that allow waiting on a RwLock guard. --- src/libstd/sync/rwlock.rs | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs index 1ecc8974369ab..fd538d52fb281 100644 --- a/src/libstd/sync/rwlock.rs +++ b/src/libstd/sync/rwlock.rs @@ -454,10 +454,11 @@ impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> { /// assert_eq!(*y, 1); /// ``` #[unstable(feature = "guard_map", - reason = "recently added, needs RFC for stabilization", + reason = "recently added, needs RFC for stabilization, + questionable interaction with Condvar", issue = "27746")] pub fn map(this: Self, cb: F) -> RwLockReadGuard<'rwlock, U> - where F: FnOnce(&'rwlock T) -> &'rwlock U + where F: FnOnce(&T) -> &U { let new = RwLockReadGuard { __lock: this.__lock, @@ -504,10 +505,11 @@ impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> { /// assert_eq!(&**x.read().unwrap(), &[10, 2]); /// ``` #[unstable(feature = "guard_map", - reason = "recently added, needs RFC for stabilization", + reason = "recently added, needs RFC for stabilization, + questionable interaction with Condvar", issue = "27746")] pub fn map(this: Self, cb: F) -> RwLockWriteGuard<'rwlock, U> - where F: FnOnce(&'rwlock mut T) -> &'rwlock mut U + where F: FnOnce(&mut T) -> &mut U { // Compute the new data while still owning the original lock // in order to correctly poison if the callback panics.