> On Jun 7, 2023, at 6:05 PM, Joseph Myers <jos...@codesourcery.com> wrote:
>
> On Wed, 7 Jun 2023, Qing Zhao via Gcc-patches wrote:
>
>> Are you suggesting to use identifier directly as the argument of the
>> attribute?
>> I tried this in the beginning, however, the current parser for the attribute
>> argument can not identify that this identifier is a field identifier inside
>> the same structure.
>>
>> For example:
>>
>> int count;
>> struct trailing_array_7 {
>> Int count;
>> int array_7[] __attribute ((element_count (count)));
>> };
>>
>> The identifier “count” inside the attribute will refer to the variable
>> “int count” outside of the structure.
>
> c_parser_attribute_arguments is supposed to allow an identifier as an
> attribute argument - and not look it up (the user of the attribute would
> later need to look it up in the context of the containing structure).
> Callers use attribute_takes_identifier_p to determine which attributes
> take identifiers (versus expressions) as arguments, which would need
> updating to cover the new attribute.
>
> There is a ??? comment about the case where the identifier is declared as
> a type name. That would simply be one of the cases carried over from the
> old Bison parser, and it would seem reasonable to remove that
> special-casing so that the attribute works even when the identifier is
> declared as a typedef name as an ordinary identifier, since it's fine for
> structure members to have the same name as a typedef name.
>
> Certainly taking an identifier directly seems like cleaner syntax than
> taking a string that then needs reinterpreting as an identifier.
Thanks a lot for the helpful info. I will study a little bit here to see how to
do this.
Qing
>
> --
> Joseph S. Myers
> jos...@codesourcery.com
