https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70528
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Yeah, and it rejects both #c1 and #c5 and the variants with K() = default; So, unlike PR58328 here both compilers agree, and the disagreement is just whether it is ok for libstdc++ to use the decltype?
