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.
--
Joseph S. Myers
jos...@codesourcery.com
