https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89130
--- Comment #8 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #7) > So I guess I could revert r268537 then. I don't think it was worth spending time on in the first place, but now that you have written it, it isn't as bad as I feared. I am usually in favor of **not** gratuitously rejecting things because the concept says so, unless we expect some use with SFINAE (although I see in PR 89164 that you prefer to be strict). Besides, isn't part of this patch also necessary for the if constexpr change?
