linux-offsetof.patch

--- include/llvm/Support/Allocator.h.orig	2018-04-04 12:50:36.000000000 -0400
+++ include/llvm/Support/Allocator.h	2018-04-04 12:50:59.000000000 -0400
@@ -22,6 +22,8 @@
 #include <cstddef>
 #include <cstdlib>
 
+#define offsetof(t, d) __builtin_offsetof(t, d)
+
 namespace llvm {
 template <typename T> struct ReferenceAdder { typedef T& result; };
 template <typename T> struct ReferenceAdder<T&> { typedef T result; };
--- tools/clang/lib/Rewrite/Core/RewriteRope.cpp.orig	2018-04-04 21:01:57.000000000 -0400
+++ tools/clang/lib/Rewrite/Core/RewriteRope.cpp	2018-04-04 21:02:57.000000000 -0400
@@ -792,7 +792,7 @@ RopePiece RewriteRope::MakeRopeString(co
   if (AllocBuffer && --AllocBuffer->RefCount == 0)
     delete [] (char*)AllocBuffer;
 
-  unsigned AllocSize = offsetof(RopeRefCountString, Data) + AllocChunkSize;
+  unsigned AllocSize = __builtin_offsetof(RopeRefCountString, Data) + AllocChunkSize;
   AllocBuffer = reinterpret_cast<RopeRefCountString *>(new char[AllocSize]);
   AllocBuffer->RefCount = 0;
   memcpy(AllocBuffer->Data, Start, Len);