PR21909: Don't try (and crash) to generate debug info for explicit instantiations of explicit specializations.

llvm-svn: 224394
diff --git a/clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp b/clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp
index 506c0d5..4613038 100644
--- a/clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp
+++ b/clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp
@@ -91,3 +91,11 @@
 extern template class j<int>;
 j<int> jj;
 // CHECK: ; [ DW_TAG_structure_type ] [j<int, int>]
+
+template <typename T>
+struct k {
+};
+template <>
+struct k<int>;
+template struct k<int>;
+// CHECK-NOT: ; [ DW_TAG_structure_type ] [k<int>]