https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70029
--- Comment #13 from Jason Merrill <jason at gcc dot gnu.org> --- I believe r241831 fixed the actual problem that verify_type was catching. This still fails because free_lang_data_in_type clears TYPE_LANG_FLAG_4 on 't' but not 'ct'. Should something have added TYPE_CANONICAL to fld.types?