https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84684
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 43562 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43562&action=edit pr84684-7.ii Even with this simplified version I still get: pr84684-6.C: In instantiation of ‘static constexpr auto union_composition<idx, alphabet_types>::make_value_to_char() [with int idx = 0; alphabet_types = {dna4}]’: pr84684-6.C:79:67: required from here pr84684-6.C:43:47: error: static assertion failed }; pr84684-6.C:83:33: error: static assertion failed static_assert (value_to_char_tables[2][1] == check[idx][2][1]); with -std=c++17, no errors with -std=c++17 -O2.
