On Tue, Dec 05, 2023 at 06:00:31PM +0100, Jakub Jelinek wrote:
> On Tue, Dec 05, 2023 at 09:45:32AM -0500, Marek Polacek wrote:
> > > When working on the previous patch I put [[]] [[]] asm (""); into a
> > > testcase, but was surprised it wasn't parsed.
> >
> > By wasn't parsed you mean we gave an error, right? I only see an error
> > with block-scope [[]] [[]];.
>
> Yeah.
> The reason why [[]][[]]; works at namespace scope is that if
> else if (cp_lexer_nth_token_is (parser->lexer,
> cp_parser_skip_std_attribute_spec_seq
> (parser,
> 1),
> CPP_SEMICOLON))
> which is the case here then even if after parsing the attributes next token
> isn't CPP_SEMICOLON (the case here without the patch), it will just return
> and another cp_parser_declaration will parse another [[]], that time also
> with CPP_SEMICOLON.
>
> > It seems marginally better to me to use void_list_node so that we don't
> > need a new parm, like what we do when parsing parameters: ()/(void)/(...),
> > but I should let others decide.
>
> Here is a modified version of the patch which does it like that.
Thanks, this looks good to me.
> 2023-12-05 Jakub Jelinek <ja...@redhat.com>
>
> * parser.cc (cp_parser_std_attribute_spec): Return void_list_node
> rather than NULL_TREE if token is neither CPP_OPEN_SQUARE nor
> RID_ALIGNAS CPP_KEYWORD.
> (cp_parser_std_attribute_spec_seq): For attr_spec == void_list_node
> break, for attr_spec == NULL_TREE continue.
>
> * g++.dg/cpp0x/gen-attrs-79.C: New test.
>
> --- gcc/cp/parser.cc.jj 2023-12-05 16:18:32.224909370 +0100
> +++ gcc/cp/parser.cc 2023-12-05 17:07:34.690170639 +0100
> @@ -30244,7 +30244,11 @@ void cp_parser_late_contract_condition (
> [ [ assert : contract-mode [opt] : conditional-expression ] ]
> [ [ pre : contract-mode [opt] : conditional-expression ] ]
> [ [ post : contract-mode [opt] identifier [opt] :
> - conditional-expression ] ] */
> + conditional-expression ] ]
> +
> + Return void_list_node if the current token doesn't start an
> + attribute-specifier to differentiate from NULL_TREE returned e.g.
> + for [ [ ] ]. */
>
> static tree
> cp_parser_std_attribute_spec (cp_parser *parser)
> @@ -30324,7 +30328,7 @@ cp_parser_std_attribute_spec (cp_parser
>
> if (token->type != CPP_KEYWORD
> || token->keyword != RID_ALIGNAS)
> - return NULL_TREE;
> + return void_list_node;
>
> cp_lexer_consume_token (parser->lexer);
> maybe_warn_cpp0x (CPP0X_ATTRIBUTES);
> @@ -30397,8 +30401,12 @@ cp_parser_std_attribute_spec_seq (cp_par
> while (true)
> {
> tree attr_spec = cp_parser_std_attribute_spec (parser);
> - if (attr_spec == NULL_TREE)
> + if (attr_spec == void_list_node)
> break;
> + /* Accept [[]][[]]; for which cp_parser_std_attribute_spec
> + returns NULL_TREE as there are no attributes. */
> + if (attr_spec == NULL_TREE)
> + continue;
> if (attr_spec == error_mark_node)
> return error_mark_node;
>
> --- gcc/testsuite/g++.dg/cpp0x/gen-attrs-79.C.jj 2023-12-05
> 17:04:14.235988879 +0100
> +++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-79.C 2023-12-05 17:04:14.235988879
> +0100
> @@ -0,0 +1,9 @@
> +// { dg-do compile { target c++11 } }
> +
> +[[]] [[]];
> +
> +[[]] [[]] void
> +foo ()
> +{
> + [[]] [[]];
> +}
Marek
