https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113366
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- It seems like there's no macro predefined by the front end to tell me -fconcepts-ts is being used? It defines __cpp_concepts=201507L for C++17 mode, but for C++20 that is __cpp_concepts=202002L instead (as required for C++20). If there was a macro telling me the non-C++20 -fconcepts-ts parsing code was in use, I could just omit the always_inline attributes entirely. That would be simpler. Having no way to tell that the compiler is in a broken^W non-conforming mode isn't helpful.
