Be a little more careful when trying to extract a TypeDecl from a enum/class/struct/union specifier; in invalid code, we may also see ClassTemplateDecls.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86171 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index f003127..93ef1ea 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -229,7 +229,8 @@
   case DeclSpec::TST_enum:
   case DeclSpec::TST_union:
   case DeclSpec::TST_struct: {
-    TypeDecl *D = cast_or_null<TypeDecl>(static_cast<Decl *>(DS.getTypeRep()));
+    TypeDecl *D 
+      = dyn_cast_or_null<TypeDecl>(static_cast<Decl *>(DS.getTypeRep()));
     if (!D) {
       // This can happen in C++ with ambiguous lookups.
       Result = Context.IntTy;