[C++ Patch] PR 69095

[Paolo Carlini <paolo.carlini@oracle.com>]

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Hi,

finally sending a patch for this issue. As noticed by submitter himself, 
it appears to boil down to a rather straightforward case of not 
rejecting unexpanded parameter packs in default arguments. In order to 
handle all the combinations (in/out of class, template 
parameter/function parameter) I added calls of 
check_for_bare_parameter_packs both to cp_parser_default_argument and 
cp_parser_late_parsing_default_args (to have a meaningful location for 
the latter, the patchlet which I sent earlier today is a must). Tested 
x86_64-linux.

Thanks,
Paolo.

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/cp
2016-05-22  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/69095
	* parser.c (cp_parser_default_argument): Call
	check_for_bare_parameter_packs.
	(cp_parser_late_parsing_default_args): Likewise.

/testsuite
2016-05-22  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/69095
	* g++.dg/cpp0x/variadic168.C: New.

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Index: cp/parser.c
===================================================================
--- cp/parser.c	(revision 236569)
+++ cp/parser.c	(working copy)
@@ -20673,6 +20673,8 @@ cp_parser_default_argument (cp_parser *parser, boo
     }
   if (BRACE_ENCLOSED_INITIALIZER_P (default_argument))
     maybe_warn_cpp0x (CPP0X_INITIALIZER_LISTS);
+  if (check_for_bare_parameter_packs (default_argument))
+    default_argument = error_mark_node;
   if (template_parm_p)
     pop_deferring_access_checks ();
   parser->greater_than_is_operator_p = saved_greater_than_is_operator_p;
@@ -26403,6 +26405,9 @@ cp_parser_late_parsing_default_args (cp_parser *pa
 	  continue;
 	}
 
+      if (check_for_bare_parameter_packs (parsed_arg))
+	parsed_arg = error_mark_node;
+
       TREE_PURPOSE (parm) = parsed_arg;
 
       /* Update any instantiations we've already created.  */
Index: testsuite/g++.dg/cpp0x/variadic168.C
===================================================================
--- testsuite/g++.dg/cpp0x/variadic168.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/variadic168.C	(working copy)
@@ -0,0 +1,18 @@
+// PR c++/69095
+// { dg-do compile { target c++11 } }
+
+struct B1 {
+  template <typename Ret, typename... Args, unsigned = sizeof(Args)> // { dg-error "parameter packs not expanded" }
+  void insert(Ret);
+};
+
+struct B2 {
+  template <typename Ret, typename... Args>
+  void insert(Ret, unsigned = sizeof(Args)); // { dg-error "parameter packs not expanded" }
+};
+
+template <typename Ret, typename... Args, unsigned = sizeof(Args)> // { dg-error "parameter packs not expanded" }
+void insert1(Ret);
+
+template <typename Ret, typename... Args>
+void insert2(Ret, unsigned = sizeof(Args)); // { dg-error "parameter packs not expanded" }