fix PR4026: Clang can't codegen __func__ without implicit cast


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69747 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/exprs.c b/test/CodeGen/exprs.c
index 0e74b8c..f80ee41 100644
--- a/test/CodeGen/exprs.c
+++ b/test/CodeGen/exprs.c
@@ -94,3 +94,8 @@
 int f6(int a0, struct s6 a1, struct s6 a2) {
   return (a0 ? a1 : a2).f0;
 }
+
+// PR4026
+void f7() {
+  __func__;
+}