On Fri, 3 Jun 2022, Marek Polacek via Gcc-patches wrote: > However, the patch does not touch the C FE. The C FE doesn't have > a counterpart to C++'s cp_parser_attributes_opt -- it only has > c_parser_transaction_attributes (which parses both GNU and [[]] > attributes), but that's TM-specific. The C FE seems to use either > c_parser_gnu_attributes or c_parser_std_attribute_specifier_sequence. > As a consequence, this works: > > [[maybe_unused]] __attribute__((deprecated)) void f2 (); > > but this doesn't: > > __attribute__((deprecated)) [[maybe_unused]] void f1 (); > > I'm not sure what, if anything, should be done about this.
In many places, both GNU and [[]] attributes are valid, but appertain to different entities, so it would be hard to define semantics for mixing them. At the start of a declaration like that, for example, GNU attributes can be mixed arbitrarily among the declaration specifiers (and appertain to the declaration) - but [[]] attributes can appear only before the declaration specifiers (appertaining to the declaration) or after them (appertaining to the type determined by those declaration specifiers), not in the middle. -- Joseph S. Myers jos...@codesourcery.com
