https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108619
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to gccbugzilla from comment #3)
> (In reply to Andrew Pinski from comment #2)
> > Once I add:
> >
> > template <class Type> struct rebind {
> > typedef alloc<Type> other;
> > };
> >
> > To alloc, it works correctly.
> > The error message on the trunk gives the best error message of what is going
> > wrong even.
> > So this is invalid.
>
> I just tried, but apparently it doesn't work
> (https://godbolt.org/z/ehhzYd5Wo)
>
> Have I misinterpreted your response? Also rebind is too optional, it's still
> a bug if it doesn't compile without it.
I missed -std=c++20 part before. The rebind fixes the compiliation issue
without -std=c++20 ....
