[Bug c++/92268] [concepts] hard error satisfying return-type-requirement

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92268

--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes those tests exercise some weird, contrived corner cases. I messed some up
and will fix them (and remove my workaround for this bug - thanks!)