From 384608e90d42cd8111b78efdea30fe06df19226a Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Sat, 7 Jul 2012 20:01:52 +0000
Subject: [PATCH] Apply constexpr to the mutex constructor.  As a conforming
 extension, apply constexpr to the condition_variable constructor.  These are
 important because it enables the compiler to construct these types at compile
 time, even though the object will be non-const.  Since they are constructed
 at compile time, there is no chance of a data race before they are
 constructed.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@159901 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/__mutex_base | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/__mutex_base b/include/__mutex_base
index 5410272b4..854f02c43 100644
--- a/include/__mutex_base
+++ b/include/__mutex_base
@@ -38,7 +38,11 @@ class _LIBCPP_VISIBLE mutex
 
 public:
     _LIBCPP_INLINE_VISIBILITY
+#ifndef _LIBCPP_HAS_NO_CONSTEXPR
+     constexpr mutex() : __m_ PTHREAD_MUTEX_INITIALIZER {}
+#else
      mutex() {__m_ = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;}
+#endif
      ~mutex();
 
 private:
@@ -297,7 +301,11 @@ class _LIBCPP_VISIBLE condition_variable
     pthread_cond_t __cv_;
 public:
     _LIBCPP_INLINE_VISIBILITY
+#ifndef _LIBCPP_HAS_NO_CONSTEXPR
+    constexpr condition_variable() : __cv_ PTHREAD_COND_INITIALIZER {}
+#else
     condition_variable() {__cv_ = (pthread_cond_t)PTHREAD_COND_INITIALIZER;}
+#endif
     ~condition_variable();
 
 private: