Shipping multiple feature-test macros for the same feature is trivially simple for implementors. Requiring users to check multiple feature-test macros to detect a single feature - the detection needs to work both in old and new implementations - seems hostile.
On Mon, Nov 25, 2019, 13:21 Ville Voutilainen via Lib <[email protected]> wrote: > On Mon, 25 Nov 2019 at 23:11, Billy O'Neal (VC LIBS) via Lib > <[email protected]> wrote: > > > > This was explicitly brought up for review in LWG and if I recall > correctly the result was that we were OK with this inconsistency since that > feature test macro had already been shipping in implementation(s). > > Vague recollections are not worth much to me. This is at > http://wiki.edg.com/bin/view/Wg21belfast/LWGThursdayAfternoon > > "Discussion about inconsistency of __cpp_lib_array_constexpr vs > __cpp_lib_constexpr_*header* > Consistency is nice, but not necessary. No consensus to change. " > > Granted, those notes aren't worth much to me either. :) They do seem > to indicate that LWG discussed this > very matter. I still don't see a very convincing reason to deviate > from the policy, considering Richard's correct > remark that the existing feature-testing macro can continue to ship. > _______________________________________________ > Lib mailing list > [email protected] > Subscription: https://lists.isocpp.org/mailman/listinfo.cgi/lib > Link to this post: http://lists.isocpp.org/lib/2019/11/14516.php >
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