From f3e767754031663427d66f57266ade5a20333aad Mon Sep 17 00:00:00 2001
From: Marshall Clow <mclow.lists@gmail.com>
Date: Mon, 9 Jan 2017 22:32:11 +0000
Subject: [PATCH] Swap two lines in __mutex_base. On systems with high clock
 rates, we could mistakenly return no_timeout when a mutex had timed out if we
 got a tick between these two lines.  Thanks to Brian Cain for the bug report.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291492 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/__mutex_base | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/__mutex_base b/include/__mutex_base
index cce928784..21638ee32 100644
--- a/include/__mutex_base
+++ b/include/__mutex_base
@@ -410,8 +410,8 @@ condition_variable::wait_for(unique_lock<mutex>& __lk,
     typedef time_point<system_clock, duration<long double, nano> > __sys_tpf;
     typedef time_point<system_clock, nanoseconds> __sys_tpi;
     __sys_tpf _Max = __sys_tpi::max();
-    system_clock::time_point __s_now = system_clock::now();
     steady_clock::time_point __c_now = steady_clock::now();
+    system_clock::time_point __s_now = system_clock::now();
     if (_Max - __d > __s_now)
         __do_timed_wait(__lk, __s_now + __ceil<nanoseconds>(__d));
     else