Fix a case when the TemplateArgs vector can be empty.

llvm-svn: 72911
diff --git a/clang/test/SemaTemplate/default-arguments.cpp b/clang/test/SemaTemplate/default-arguments.cpp
index 572227c..0e4c366 100644
--- a/clang/test/SemaTemplate/default-arguments.cpp
+++ b/clang/test/SemaTemplate/default-arguments.cpp
@@ -10,3 +10,6 @@
 template<typename U = float, int M> struct X;
 
 X<> *x4;
+
+template<typename T = int> struct Z;
+template struct Z<>;