Guard against the return of PR3188

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@61348 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/SemaCXX/pr-3188.cpp b/test/SemaCXX/pr-3188.cpp
new file mode 100644
index 0000000..7d86240
--- /dev/null
+++ b/test/SemaCXX/pr-3188.cpp
@@ -0,0 +1,3 @@
+// RUN: clang -fsyntax-only %s
+struct x;
+extern x a;