From 796b380ca7d263ca504b82fe5317a78d3546d537 Mon Sep 17 00:00:00 2001
From: Alex James <theracermaster@gmail.com>
Date: Thu, 28 Nov 2019 13:56:45 +0800
Subject: [PATCH] MdePkg: Use __builtin_offset with CLANGPDB toolchain

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2393

CLANGPDB does not define __GNUC__, but it does define __clang__. Check
for the __clang__ preprocessor definition to use __builtin_offsetof to
implement the OFFSET_OF macro.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Alex James <theracermaster@gmail.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
---
 MdePkg/Include/Base.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
index 4680e64136..e0bcd0ae67 100644
--- a/MdePkg/Include/Base.h
+++ b/MdePkg/Include/Base.h
@@ -781,11 +781,9 @@ typedef UINTN  *BASE_LIST;
   @return  Offset, in bytes, of field.
 
 **/
-#ifdef __GNUC__
-#if __GNUC__ >= 4
+#if (defined(__GNUC__) && __GNUC__ >= 4) || defined(__clang__)
 #define OFFSET_OF(TYPE, Field) ((UINTN) __builtin_offsetof(TYPE, Field))
 #endif
-#endif
 
 #ifndef OFFSET_OF
 #define OFFSET_OF(TYPE, Field) ((UINTN) &(((TYPE *)0)->Field))