Hi again,
On 10/24/2012 09:53 PM, Jason Merrill wrote:
The parm shouldn't be a parameter pack in that case; the ... is part
of the default argument, not the parameter.
I tracked down where this goes wrong, in the parser: the below
recognizes when cp_parser_parameter_declaration doesn't parse a valid
default argument and in that case "*is_parameter_pack = true;" doesn't
happen. This means we have a very good diagnostics, only a single error
message and nothing else, not even the maybe_warn_variadic_templates
message in C++98 mode because I don't think the code can make any sense
in any C++ dialect whatsoever (the latter would be easy to change of course)
Tested x86_64-linux, as usual.
Thanks,
Paolo.
PS: interestingly, detecting error_mark_node toward the end of
cp_parser_parameter_declaration and turning it into a NULL_TREE leads to
a single regression, at the end of pr39060.C, because NULL_TREE implies
that we don't do anymore the diagnostics about default argument part of
duplicate_decls (which ICC also gives). Besides that, for 34892 we give
like 6 different error messages ;)
////////////////////////
/cp
2012-10-24 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/34892
* parser.c (cp_parser_template_parameter): Notice when parsing the
default argument goes wrong in cp_parser_parameter_declaration and
don't set is_parameter_pack in that case.
/testsuite
2012-10-24 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/34892
* g++.dg/template/crash114.C: New.
Index: testsuite/g++.dg/template/crash114.C
===================================================================
--- testsuite/g++.dg/template/crash114.C (revision 0)
+++ testsuite/g++.dg/template/crash114.C (working copy)
@@ -0,0 +1,5 @@
+// PR c++/34892
+
+template<int=..., int=0> struct A {}; // { dg-error "expected primary" }
+
+A<0> a;
Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 192786)
+++ cp/parser.c (working copy)
@@ -12267,9 +12267,18 @@ cp_parser_template_parameter (cp_parser* parser, b
{
/* Consume the `...'. */
cp_lexer_consume_token (parser->lexer);
- maybe_warn_variadic_templates ();
-
- *is_parameter_pack = true;
+
+ /* For an erroneous input like (c++/34892):
+
+ template<int=..., int=0> struct A {};
+
+ we gave an error in cp_parser_parameter_declaration and returned a
+ parameter_declarator with error_mark_node as default_argument. */
+ if (parameter_declarator->default_argument != error_mark_node)
+ {
+ maybe_warn_variadic_templates ();
+ *is_parameter_pack = true;
+ }
}
/* We might end up with a pack expansion as the type of the non-type
template parameter, in which case this is a non-type template
