On Tue, Dec 05, 2023 at 08:51:51AM +0100, Jakub Jelinek wrote:
> Hi!
>
> 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 [[]] [[]];.
> The problem is that when cp_parser_std_attribute_spec returns NULL, it
> can mean 2 different things, one is that the next token(s) are neither
> [[ nor alignas (in that case the caller should break from the loop),
> or when we parsed something like [[]] - it was valid attribute specifier,
> but didn't specify any attributes in it.
>
> The following patch fixes that by adding another parameter to differentiate
> between the cases, guess another option would be to use some magic
> tree value for the break case instead of NULL_TREE (but error_mark_node is
> already taken and means something else).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> Or shall I go with some magic return which will never happen otherwise?
> void_node?
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.
If we stay with any_p, please add a comment saying that it means "found any",
not "accepts any" or something else. Thanks,
> 2023-12-05 Jakub Jelinek <ja...@redhat.com>
>
> * parser.cc (cp_parser_std_attribute_spec): Add ANY_P argument, set
> what it points to initially to true and only if token is neither
> CPP_OPEN_SQUARE nor RID_ALIGNAS CPP_KEYWORD set it to false.
> (cp_parser_std_attribute_spec_seq): Adjust
> cp_parser_std_attribute_spec caller. If it returns NULL_TREE and
> any_p is true, continue rather than break.
>
> * g++.dg/cpp0x/gen-attrs-79.C: New test.
>
> --- gcc/cp/parser.cc.jj 2023-12-04 20:23:53.225009856 +0100
> +++ gcc/cp/parser.cc 2023-12-04 20:49:21.160426104 +0100
> @@ -2703,7 +2703,7 @@ static tree cp_parser_gnu_attribute_list
> static tree cp_parser_std_attribute
> (cp_parser *, tree);
> static tree cp_parser_std_attribute_spec
> - (cp_parser *);
> + (cp_parser *, bool *);
> static tree cp_parser_std_attribute_spec_seq
> (cp_parser *);
> static size_t cp_parser_skip_std_attribute_spec_seq
> @@ -30265,11 +30265,12 @@ void cp_parser_late_contract_condition (
> conditional-expression ] ] */
>
> static tree
> -cp_parser_std_attribute_spec (cp_parser *parser)
> +cp_parser_std_attribute_spec (cp_parser *parser, bool *any_p)
> {
> tree attributes = NULL_TREE;
> cp_token *token = cp_lexer_peek_token (parser->lexer);
>
> + *any_p = true;
> if (token->type == CPP_OPEN_SQUARE
> && cp_lexer_peek_nth_token (parser->lexer, 2)->type == CPP_OPEN_SQUARE)
> {
> @@ -30342,7 +30343,10 @@ cp_parser_std_attribute_spec (cp_parser
>
> if (token->type != CPP_KEYWORD
> || token->keyword != RID_ALIGNAS)
> - return NULL_TREE;
> + {
> + *any_p = false;
> + return NULL_TREE;
> + }
>
> cp_lexer_consume_token (parser->lexer);
> maybe_warn_cpp0x (CPP0X_ATTRIBUTES);
> @@ -30414,9 +30418,16 @@ cp_parser_std_attribute_spec_seq (cp_par
>
> while (true)
> {
> - tree attr_spec = cp_parser_std_attribute_spec (parser);
> + bool any_p;
> + tree attr_spec = cp_parser_std_attribute_spec (parser, &any_p);
> if (attr_spec == NULL_TREE)
> - break;
> + {
> + /* Accept [[]][[]]; for which cp_parser_std_attribute_spec
> + also returns NULL_TREE as there are no attributes. */
> + if (any_p)
> + continue;
> + break;
> + }
> if (attr_spec == error_mark_node)
> return error_mark_node;
>
> --- gcc/testsuite/g++.dg/cpp0x/gen-attrs-79.C.jj 2023-12-04
> 20:38:35.122574430 +0100
> +++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-79.C 2023-12-04 20:38:29.468654143
> +0100
> @@ -0,0 +1,9 @@
> +// { dg-do compile { target c++11 } }
> +
> +[[]] [[]];
> +
> +[[]] [[]] void
> +foo ()
> +{
> + [[]] [[]];
> +}
>
> Jakub
>
Marek
