re PR c++/35828 ([C++0x] ICE on default template template parameter in template function)

	PR c++/35828
	* pt.c (tsubst_decl): Don't abort if we didn't change anything
	in a TEMPLATE_DECL's args.

From-SVN: r149351

gcc/cp/ChangeLog

+2009-07-07  Jason Merrill  <jason@redhat.com>
+
+	PR c++/35828
+	* pt.c (tsubst_decl): Don't abort if we didn't change anything
+	in a TEMPLATE_DECL's args.
+
 2009-07-07  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
 	* semantics.c (finalize_nrv_r): Replace EXPR_LOCUS by

gcc/cp/pt.c

@@ -8306,8 +8306,7 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
     case TEMPLATE_DECL:
       {
 	/* We can get here when processing a member function template,
-	   member class template, and template template parameter of
-	   a template class.  */
+	   member class template, or template template parameter.  */
 	tree decl = DECL_TEMPLATE_RESULT (t);
 	tree spec;
 	tree tmpl_args;
@@ -8351,10 +8350,10 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
 	if (full_args == error_mark_node)
 	  return error_mark_node;
 
-	/* tsubst_template_args doesn't copy the vector if
-	   nothing changed.  But, *something* should have
-	   changed.  */
-	gcc_assert (full_args != tmpl_args);
+	/* If this is a default template template argument,
+	   tsubst might not have changed anything.  */
+	if (full_args == tmpl_args)
+	  return t;
 
 	hash = hash_tmpl_and_args (t, full_args);
 	spec = retrieve_specialization (t, full_args, hash);

gcc/testsuite/ChangeLog

 2009-07-07  Jason Merrill  <jason@redhat.com>
 
+	PR c++/35828
+	* g++.dg/template/defarg12.C: New.
+
 	PR c++/37816
 	* g++.dg/cpp0x/enum7.C: New.
 

gcc/testsuite/g++.dg/template/defarg12.C

+// PR c++/35828
+// { dg-options "-std=c++0x" }
+
+template < typename > struct A ;
+template < template < typename > class = A >
+void test ()
+{
+        test ();
+}
+