PR c++/78282 - auto template and pack expansion

	* pt.c (find_parameter_packs_r): Don't walk into the type of
	templates other than template template-parameters.

From-SVN: r245594

gcc/cp/ChangeLog

 2017-02-19  Jason Merrill  <jason@redhat.com>
 
+	PR c++/78282 - auto template and pack expansion
+	* pt.c (find_parameter_packs_r): Don't walk into the type of
+	templates other than template template-parameters.
+
 	PR c++/79606 - ICE with this->base_member in NSDMI
 	* class.c (build_base_path): Check processing_template_decl.
 

gcc/cp/pt.c

@@ -3576,8 +3576,12 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
       *walk_subtrees = 0;
       return NULL_TREE;
 
-    case CONSTRUCTOR:
     case TEMPLATE_DECL:
+      if (!DECL_TEMPLATE_TEMPLATE_PARM_P (t))
+	return NULL_TREE;
+      gcc_fallthrough();
+
+    case CONSTRUCTOR:
       cp_walk_tree (&TREE_TYPE (t),
 		    &find_parameter_packs_r, ppd, ppd->visited);
       return NULL_TREE;

gcc/testsuite/g++.dg/cpp1y/auto-fn36.C

+// PR c++/78282
+// { dg-do compile { target c++14 } }
+
+struct null_node
+{
+  null_node(const null_node&);
+};
+
+extern null_node null;
+
+template <typename T>
+auto get() { return null; }
+
+template <typename... Ts>
+struct inheritor: Ts...
+{
+  inheritor(const inheritor& outer)
+    : Ts(get<Ts...>())...
+    { }
+};
+
+void test()
+{
+  extern inheritor<null_node> example;
+  inheritor<null_node> result(example);
+}