re PR c++/56646 (ICE: in cp_parser_late_return_type_opt, at cp/parser.c:16970)

	PR c++/56646
	* parser.c (cp_parser_late_return_type_opt): Save and restore
	current_class_ptr/ref.

From-SVN: r196853

gcc/cp/ChangeLog

 2013-03-20  Jason Merrill  <jason@redhat.com>
 
+	PR c++/56646
+	* parser.c (cp_parser_late_return_type_opt): Save and restore
+	current_class_ptr/ref.
+
 	PR c++/54532
 	* expr.c (cplus_expand_constant): Do nothing if the class is
 	incomplete.

gcc/cp/parser.c

@@ -17056,17 +17056,21 @@ cp_parser_late_return_type_opt (cp_parser* parser, cp_cv_quals quals)
   /* Consume the ->.  */
   cp_lexer_consume_token (parser->lexer);
 
+  tree save_ccp = current_class_ptr;
+  tree save_ccr = current_class_ref;
   if (quals >= 0)
     {
       /* DR 1207: 'this' is in scope in the trailing return type.  */
-      gcc_assert (current_class_ptr == NULL_TREE);
       inject_this_parameter (current_class_type, quals);
     }
 
   type = cp_parser_trailing_type_id (parser);
 
   if (quals >= 0)
-    current_class_ptr = current_class_ref = NULL_TREE;
+    {
+      current_class_ptr = save_ccp;
+      current_class_ref = save_ccr;
+    }
 
   return type;
 }

gcc/testsuite/g++.dg/cpp0x/trailing9.C

+// PR c++/56646
+// { dg-require-effective-target c++11 }
+
+struct A {
+  void f();
+};
+
+void A::f() {
+  struct B {
+    auto g() -> void { }
+  };
+}