[Bug c++/93699] Invalid operator== (returning non-bool type) candidate

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93699

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Personally, I think it should remain ill-formed.

Maybe -fpermissive could allow it (for compat with previous standards) but
unfortunately that flag is far too permissive and enables all kinds of ancient
legacy junk. If we cleaned it up to be a bit permissive, not ridiculously
permissive of pre-1998 code, it could be useful here.