https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118387
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- My reading of the patch review comment https://gcc.gnu.org/pipermail/gcc-patches/2025-January/673245.html was that this is a defect in the standard and we should treat it as a reason to make the defaulted function deleted. Which is what I'll try to implement next week.