From d547ac0df9ee094e1d93aae9a5dec72f030e2436 Mon Sep 17 00:00:00 2001
From: Asiri Rathnayake <asiri.rathnayake@arm.com>
Date: Tue, 13 Sep 2016 09:32:32 +0000
Subject: [libcxx] Fix gcc builds.

Step around a gcc pre-processor defect which causes it to fail to
parse the __has_include macro check.

llvm-svn: 281310
---
 libcxx/include/__threading_support | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

(limited to 'libcxx/include/__threading_support')

diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
index b36a52ec9cc..86dc8c7be82 100644
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -19,9 +19,20 @@
 
 #ifndef _LIBCPP_HAS_NO_THREADS
 
-#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL) && (!defined(__has_include) || __has_include(<__external_threading>))
+// These checks are carefully arranged so as not to trigger a gcc pre-processor
+// defect which causes it to fail to parse the __has_include check below, the
+// redundancy is intentional.
+#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL)
+#if !defined(__clang__) && (_GNUC_VER < 500)
 #include <__external_threading>
-#else
+#define _LIBCPP_EXTERNAL_THREADING
+#elif !defined(__has_include) || __has_include(<__external_threading>)
+#include <__external_threading>
+#define _LIBCPP_EXTERNAL_THREADING
+#endif
+#endif
+
+#if !defined(_LIBCPP_EXTERNAL_THREADING)
 #include <pthread.h>
 #include <sched.h>
 #endif
-- 
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