From cee23446e1c50ef7c6d6906c9146460a198803fa Mon Sep 17 00:00:00 2001
From: Marshall Clow <mclow.lists@gmail.com>
Date: Wed, 2 Nov 2016 17:56:05 +0000
Subject: [PATCH] Add support for old versions of MacOS to libunwind. Fixes
 PR22203. Thanks to Jeremy for the bug report and the patch.

llvm-svn: 285845
---
 libunwind/include/libunwind.h | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/libunwind/include/libunwind.h b/libunwind/include/libunwind.h
index b52fe9d..9d72d48 100644
--- a/libunwind/include/libunwind.h
+++ b/libunwind/include/libunwind.h
@@ -20,12 +20,26 @@
 #include <stddef.h>
 
 #ifdef __APPLE__
-  #include <Availability.h>
-    #ifdef __arm__
-       #define LIBUNWIND_AVAIL __attribute__((unavailable))
+  #if __clang__
+    #if __has_include(<Availability.h>)
+      #include <Availability.h>
+    #endif
+  #elif __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
+    #include <Availability.h>
+  #endif
+
+  #ifdef __arm__
+     #define LIBUNWIND_AVAIL __attribute__((unavailable))
+  #elif defined(__OSX_AVAILABLE_STARTING)
+    #define LIBUNWIND_AVAIL __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_5_0)
+  #else
+    #include <AvailabilityMacros.h>
+    #ifdef AVAILABLE_MAC_OS_X_VERSION_10_6_AND_LATER
+      #define LIBUNWIND_AVAIL AVAILABLE_MAC_OS_X_VERSION_10_6_AND_LATER
     #else
-      #define LIBUNWIND_AVAIL __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_5_0)
+      #define LIBUNWIND_AVAIL __attribute__((unavailable))
     #endif
+  #endif
 #else
   #define LIBUNWIND_AVAIL
 #endif
-- 
2.7.4