fix a crash compiling code with its own definition of objc_assign_weak.
rdar://6800430

llvm-svn: 69392
diff --git a/clang/test/CodeGenObjC/runtime-fns.m b/clang/test/CodeGenObjC/runtime-fns.m
index c53b0a3..0d85707 100644
--- a/clang/test/CodeGenObjC/runtime-fns.m
+++ b/clang/test/CodeGenObjC/runtime-fns.m
@@ -25,4 +25,9 @@
 id objc_msgSend(int x) {
   return 0;
 }
+
+// rdar://6800430
+void objc_assign_weak(id value, id *location) {
+}
+
 #endif