Index: lib/Sema/SemaDeclCXX.cpp
===================================================================
--- lib/Sema/SemaDeclCXX.cpp	(revision 161235)
+++ lib/Sema/SemaDeclCXX.cpp	(working copy)
@@ -9473,7 +9473,7 @@
       TemplateParameterList *Params = TpDecl->getTemplateParameters();
       if (Params->size() == 1) {
         NonTypeTemplateParmDecl *PmDecl =
-          cast<NonTypeTemplateParmDecl>(Params->getParam(0));
+          dyn_cast<NonTypeTemplateParmDecl>(Params->getParam(0));
 
         // The template parameter must be a char parameter pack.
         if (PmDecl && PmDecl->isTemplateParameterPack() &&
Index: test/SemaCXX/literal-operators.cpp
===================================================================
--- test/SemaCXX/literal-operators.cpp	(revision 161235)
+++ test/SemaCXX/literal-operators.cpp	(working copy)
@@ -41,3 +41,4 @@
 template <char...> void operator "" _good ();
 
 // FIXME: Test some invalid decls that might crop up.
+template <typename...> void operator "" _invalid(); // expected-error {{parameter declaration for literal operator 'operator "" _invalid' is not valid}}