PR c++/78767 - ICE with inherited constructor default argument

	* method.c (strip_inheriting_ctors): Strip template as appropriate.

From-SVN: r243864

gcc/cp/ChangeLog

 2016-12-21  Jason Merrill  <jason@redhat.com>
 
+	PR c++/78767 - ICE with inherited constructor default argument
+	* method.c (strip_inheriting_ctors): Strip template as appropriate.
+
 	PR c++/78749 - friend in anonymous namespace
 	* decl.c (wrapup_globals_for_namespace): Don't complain about friend
 	pseudo-template instantiations.

gcc/cp/method.c

@@ -496,14 +496,18 @@ forward_parm (tree parm)
    constructor from a (possibly indirect) base class.  */
 
 tree
-strip_inheriting_ctors (tree fn)
+strip_inheriting_ctors (tree dfn)
 {
   gcc_assert (flag_new_inheriting_ctors);
+  tree fn = dfn;
   while (tree inh = DECL_INHERITED_CTOR (fn))
     {
       inh = OVL_CURRENT (inh);
       fn = inh;
     }
+  if (TREE_CODE (fn) == TEMPLATE_DECL
+      && TREE_CODE (dfn) == FUNCTION_DECL)
+    fn = DECL_TEMPLATE_RESULT (fn);
   return fn;
 }
 

gcc/testsuite/g++.dg/cpp0x/inh-ctor24.C

+// PR c++/78767
+// { dg-do compile { target c++11 } }
+
+template <class T> struct A
+{
+  template <class U>
+  A(U, U = 42);
+};
+
+struct B: A<int>
+{
+  using A::A;
+};
+
+B b(24);