From a0d8701017e9ccea3f4a200714ca7c7c61eae406 Mon Sep 17 00:00:00 2001
From: Andre Bogus <bogusandre@gmail.com>
Date: Fri, 8 Apr 2016 00:31:58 +0200
Subject: [PATCH] impl Default for CondVar, Mutex and RwLock

---
 src/libstd/sync/condvar.rs | 9 +++++++++
 src/libstd/sync/mutex.rs   | 9 +++++++++
 src/libstd/sync/rwlock.rs  | 9 +++++++++
 3 files changed, 27 insertions(+)

diff --git a/src/libstd/sync/condvar.rs b/src/libstd/sync/condvar.rs
index 64468be396f34..6e97fbd205eeb 100644
--- a/src/libstd/sync/condvar.rs
+++ b/src/libstd/sync/condvar.rs
@@ -227,6 +227,15 @@ impl Drop for Condvar {
     }
 }
 
+#[unstable(feature = "defaults",
+           reason = "has not yet been decided",
+           issue = "31865")]
+impl Default for Condvar {
+    fn default() -> Condvar {
+        Condvar::new()
+    }
+}
+
 impl StaticCondvar {
     /// Creates a new condition variable
     #[unstable(feature = "static_condvar",
diff --git a/src/libstd/sync/mutex.rs b/src/libstd/sync/mutex.rs
index e0946a5c12a77..9ed18fd2b5e23 100644
--- a/src/libstd/sync/mutex.rs
+++ b/src/libstd/sync/mutex.rs
@@ -197,6 +197,15 @@ impl<T> Mutex<T> {
     }
 }
 
+#[unstable(feature = "defaults",
+           reason = "has not yet been decided",
+           issue = "31865")]
+impl<T: Default> Default for Mutex<T> {
+    fn default() -> Mutex<T> {
+        Mutex::new(Default::default())
+    }
+}
+
 impl<T: ?Sized> Mutex<T> {
     /// Acquires a mutex, blocking the current thread until it is able to do so.
     ///
diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
index a37c1c16a45e9..397f272bdfe3d 100644
--- a/src/libstd/sync/rwlock.rs
+++ b/src/libstd/sync/rwlock.rs
@@ -156,6 +156,15 @@ impl<T> RwLock<T> {
     }
 }
 
+#[unstable(feature = "defaults",
+           reason = "has not yet been decided",
+           issue = "31865")]
+impl<T: Default> Default for RwLock<T> {
+    fn default() -> RwLock<T> {
+        RwLock::new(Default::default())
+    }
+}
+
 impl<T: ?Sized> RwLock<T> {
     /// Locks this rwlock with shared read access, blocking the current thread
     /// until it can be acquired.