From: Core <core-bounces@lists.isocpp.org> on behalf of Herring, Davis via Core <core@lists.isocpp.org> Sent: Wednesday, February 8, 2023 11:31:47 AM To: Uecker, Martin <Martin.Uecker@med.uni-goettingen.de> Cc: Herring, Davis <herring@lanl.gov>; core@lists.isocpp.org <core@lists.isocpp.org>; Liaison@lists.isocpp.org <Liaison@lists.isocpp.org>; ext@lists.isocpp.org <ext@lists.isocpp.org> Subject: Re: [isocpp-core] [wg14/wg21 liaison] Ignorability of attributes: draft wording, and concern about __has_c_attribute
>> I'm not sure why this is different from any other feature-test macro.
>> [...]
>
> What would be the use case for this?
Well, certainly some feature-test macros indicate the presence of significant portable functionality: __cpp_lib_ranges_iota, for example. It is equally certain that feature-test macros are of less value when they indicate the presence of things that do not
have such portable functionality. Set against this is the questionable value that a "really does what I ask" test has in a context where "really" isn't very meaningful.