Re: [PATCH][_GLIBCXX_INLINE_VERSION] Fix <format> friend declarations

[Jonathan Wakely <jwakely@redhat.com>]

On Wed, 13 Sept 2023 at 21:47, François Dumont <frs.dumont@gmail.com> wrote:
>
> It's working and what's I've committed.

Nice, thanks!


>
> Thanks
>
> On 12/09/2023 19:04, Jonathan Wakely wrote:
> > On Tue, 12 Sept 2023 at 17:47, Jonathan Wakely <jwakely@redhat.com> wrote:
> >> On Wed, 23 Aug 2023 at 18:35, François Dumont via Libstdc++
> >> <libstdc++@gcc.gnu.org> wrote:
> >>> Hi
> >>>
> >>> The few tests that are failing in versioned namespace mode are due to
> >>> those friend declarations.
> >>>
> >>> This is a fix proposal even if I considered 2 other options:
> >>>
> >>> 1. Make __format::_Arg_store a struct and so do not bother with friend
> >>> declarations.
> >>>
> >>> 2. Consider it as a compiler bug and do nothing. In this case I think we
> >>> might still need this patch to avoid a non-working format library in
> >>> versioned namespace mode in gcc 14 if compiler bug is not fixed.
> >> It definitely is a compiler bug, this is PR c++/59256.
> >>
> >> Please add a comment to the new macro definition, so we remember to
> >> remove it when it's not needed:
> >>
> >>
> >> #if _GLIBCXX_INLINE_VERSION
> >> // Needed because of PR c++/59526
> >> # define _GLIBCXX_STD_V std::__8
> >> #else
> >> # define _GLIBCXX_STD_V std
> >> #endif
> >>
> >>
> >> OK with that change, thanks.
> > Actually, are you sure the friend std::basic_format_args declaration
> > needs to change?
> >
> > I only see errors for the friend function, not the friend class. So
> > this seems to fix it:
> >
> > --- a/libstdc++-v3/include/std/format
> > +++ b/libstdc++-v3/include/std/format
> > @@ -3437,7 +3437,13 @@ namespace __format
> >
> >        template<typename _Ctx, typename... _Argz>
> >         friend auto
> > -       std::make_format_args(_Argz&&...) noexcept;
> > +#if _GLIBCXX_INLINE_VERSION
> > +       // Needed for PR c++/59526
> > +       std::__8::
> > +#else
> > +       std::
> > +#endif
> > +       make_format_args(_Argz&&...) noexcept;
> >
> >        // For a sufficiently small number of arguments we only store values.
> >        // basic_format_args can get the types from the _Args pack.
> >
> >
> >
> >
> >>
> >>> I can also define _GLIBCXX_STD_V at <format> level to limit impact.
> >>>
> >>>       libstdc++: [_GLIBCXX_INLINE_VERSION] Fix <format> friend declarations
> >>>
> >>>       GCC do not consider the inline namespace in friend declarations. We
> >>> need
> >>>       to explicit this namespace.
> >>>
> >>>       libstdc++-v3/ChangeLog:
> >>>
> >>>               * include/bits/c++config (_GLIBCXX_STD_V): New macro giving
> >>> current
> >>>               std namespace with optionally the version namespace.
> >>>               * include/std/format (std::__format::_Arg_store): Use
> >>> latter on friend
> >>>               declarations.
> >>>
> >>> Tested under versioned mode.
> >>>
> >>> Ok to commit ?
> >>>
> >>> François
>