Improve the test for unused-expression warnings slightly

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93644 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/SemaCXX/unused.cpp b/test/SemaCXX/unused.cpp
index 6fd1081..88783ce 100644
--- a/test/SemaCXX/unused.cpp
+++ b/test/SemaCXX/unused.cpp
@@ -13,3 +13,12 @@
   APInt::operator=(RHS);
   return *this;
 }
+
+template<typename T>
+struct X {
+  X();
+};
+
+void test() {
+  X<int>();
+}