From 69e53c4cdb5dcd8b2eb22ff3bd559d08d0832383 Mon Sep 17 00:00:00 2001
From: theraven <theraven@72102866-910b-0410-8b05-ffd578937521>
Date: Tue, 5 Jul 2011 08:59:58 +0000
Subject: [PATCH] Better test for presence of __sync_swap().

---
 gc_boehm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gc_boehm.c b/gc_boehm.c
index 7c91caf..496338b 100644
--- a/gc_boehm.c
+++ b/gc_boehm.c
@@ -58,7 +58,10 @@ struct objc_slot* objc_get_slot(Class cls, SEL selector);
 #include <gc/gc.h>
 #include <gc/gc_typed.h>
 
-#ifndef __clang__
+#ifndef __has_builtin
+#	define __has_builtin(x) 0
+#endif
+#if __has_builtin(__sync_swap)
 #define __sync_swap __sync_lock_test_and_set
 #endif