From 4f2c83f0558706eb8d93314f935f89d420121441 Mon Sep 17 00:00:00 2001
From: Asiri Rathnayake <asiri.rathnayake@arm.com>
Date: Fri, 14 Oct 2016 13:56:58 +0000
Subject: [PATCH] [libcxx] Improve the gcc workaround for the missing
 __has_include macro.

NFC.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@284237 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/__threading_support | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/include/__threading_support b/include/__threading_support
index af3109efd..36f1701f1 100644
--- a/include/__threading_support
+++ b/include/__threading_support
@@ -19,20 +19,18 @@
 
 #ifndef _LIBCPP_HAS_NO_THREADS
 
-// 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>
-#define _LIBCPP_HAS_EXTERNAL_THREADING_HEADER
-#elif !defined(__has_include) || __has_include(<__external_threading>)
-#include <__external_threading>
-#define _LIBCPP_HAS_EXTERNAL_THREADING_HEADER
-#endif
+#ifndef __libcpp_has_include
+  #ifndef __has_include
+    #define __libcpp_has_include(x) 0
+  #else
+    #define __libcpp_has_include(x) __has_include(x)
+  #endif
 #endif
 
-#if !defined(_LIBCPP_HAS_EXTERNAL_THREADING_HEADER)
+#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL) && \
+    __libcpp_has_include(<__external_threading>)
+#include <__external_threading>
+#else
 #include <pthread.h>
 #include <sched.h>
 
@@ -241,7 +239,7 @@ void __libcpp_tls_set(__libcpp_tls_key __key, void* __p)
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !_LIBCPP_HAS_EXTERNAL_THREADING_HEADER
+#endif // !_LIBCPP_HAS_THREAD_API_EXTERNAL || !__libcpp_has_include(<__external_threading>)
 
 #endif // _LIBCPP_HAS_NO_THREADS