From: Jeffrey Yasskin <jyasskin@google.com>
Date: Tue, 21 Feb 2012 16:20:12 +0000 (+0000)
Subject: Allow linux builds to take advantage of libunwind to get unwind.h if
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f18a87b1ce1be5ccc3b6b3dbd4f15374710e237b;p=clang

Allow linux builds to take advantage of libunwind to get unwind.h if
that's installed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151058 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Headers/unwind.h b/lib/Headers/unwind.h
index 28ad8043f2..a99c8a1176 100644
--- a/lib/Headers/unwind.h
+++ b/lib/Headers/unwind.h
@@ -23,9 +23,19 @@
 
 /* See "Data Definitions for libgcc_s" in the Linux Standard Base.*/
 
-#if defined(__APPLE__) && __has_include_next(<unwind.h>)
-/* Darwin typically has its own unwind.h; use it. */
-#  include_next <unwind.h>
+#if __has_include_next(<unwind.h>)
+/* Darwin and libunwind provide an unwind.h. If that's available, use
+ * it. libunwind wraps some of its definitions in #ifdef _GNU_SOURCE,
+ * so define that around the include.*/
+# ifndef _GNU_SOURCE
+#  define _SHOULD_UNDEFINE_GNU_SOURCE
+#  define _GNU_SOURCE
+# endif
+# include_next <unwind.h>
+# ifdef _SHOULD_UNDEFINE_GNU_SOURCE
+#  undef _GNU_SOURCE
+#  undef _SHOULD_UNDEFINE_GNU_SOURCE
+# endif
 #else
 
 #include <stdint.h>