Fix <rdar://problem/6336774> clang block rewriter: Assertion failed: Offset+NumBytes <= size() && "Invalid region to erase!", file c:\cygwin\home\Administrator\llvm\to ols\clang\include\clang/Rewrite/RewriteRope.h, line 219.

llvm-svn: 58607
diff --git a/clang/Driver/RewriteObjC.cpp b/clang/Driver/RewriteObjC.cpp
index 39f4f15..ee9e2bc2 100644
--- a/clang/Driver/RewriteObjC.cpp
+++ b/clang/Driver/RewriteObjC.cpp
@@ -3570,6 +3570,9 @@
   // Need to avoid trying to rewrite synthesized casts.
   if (LocStart.isInvalid())
     return;
+  // Need to avoid trying to rewrite casts contained in macros.
+  if (!Rewriter::isRewritable(LocStart) || !Rewriter::isRewritable(LocEnd))
+    return;
     
   const char *startBuf = SM->getCharacterData(LocStart);
   const char *endBuf = SM->getCharacterData(LocEnd);