[Bug libstdc++/77913] error building bits/locale_conv.h: expected primary-expression before ',' token

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77913

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> Who is defining __out ?

Which you can find out by -dD (or -g3).  I suspect this is not a bug in
libstdc++ but the headers of the program that is being compiled.