https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90814
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|gcc accept invalid |gcc accept invalid |constexpr defaulted |constexpr defaulted |constructor |constructor when the | |defaulted constructor would | |cause to be deleted --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- So since the defaulted constructor would be caused to be deleted, GCC accepts it instead of rejecting it. Note C++23 makes this valid (still deleted though). So this might be less of improtance now.