Attributes are not only for the compiler. Also other tooling may use them. Including reflection compile-time code. So the compiler will only know and interpret some of the used attributes.   -----Ursprüngliche Nachricht----- Von:Matheus Izvekov via Std-Proposals <std-proposals_at_[hidden]> Gesendet:Mo 24.03.2025 16:56 Betreff:Re: [std-proposals] Ignoring attributes (was: Floating an idea: [[no_address]] for functions) An:std-proposals_at_[hidden]; CC:Matheus Izvekov <mizvekov_at_[hidden]>; I don't disagree in principle with the idea of allowing more kinds of attributes, which currently ignorability rules out. But I think the status quo with vendor attributes is not very safe. Either they should be mandatory to implement, or the compiler should make it ill-formed to use an attribute it doesn't know about, which seems would be quite a breaking change. On Mon, Mar 24, 2025 at 12:11 PM Arthur O'Dwyer via Std-Proposals <std-proposals_at_[hidden]> wrote: > > On Mon, Mar 24, 2025 at 8:01 AM Jonathan Wakely via Std-Proposals <std-proposals_at_[hidden]> wrote: >> >> On Mon, 24 Mar 2025 at 09:36, Marcin Jaczewski wrote: >>> >>> pon., 24 mar 2025 o 10:13 Jonathan Wakely via Std-Proposals >>> <std-proposals_at_[hidden]> napisał(a): >>> > Yes, it seems appropriate as an attribute to me (but then I think the rule that attributes must be ignorable and can't change semantics is silly anyway). >>> >>> But for me it is right, as enforcing can be done by "clang format" >>> when you push changes to a public repo. >>> Or by other tools like PVS-Studio, or by only the developer of header >>> library (if attributes affect self use in header) and his compiler, >>> all user can use older compilers that are not aware of the attribute >>> but still indirectly benefit from it. >> >> >> Which means we can't ever standardize attributes for e.g. [[gnu::always_inline]] or [[gnu::packed]] or [[clang::musttail]] or [[no_unique_address]] (oh whoops, we did, and we come up with contorted explanations for why it isn't *really* changing semantics and ignoring it is fine), or alignas (oh right, it's defined as part of the attribute grammar but is actually a keyword, because we couldn't add it as an attribute due to the ignorable rule). >> >> Attributes are precisely the right tool for extending the semantics in particular places without having to introduce new keywords every time. > > > @jwakely: You know this, and I know this; why doesn't WG21 know this? > > –Arthur > -- > Std-Proposals mailing list > Std-Proposals_at_[hidden] > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals -- Std-Proposals mailing list Std-Proposals_at_[hidden] https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals