[Bug libstdc++/107693] undefined reference to `_ZSt8to_charsPcS_DF128_St12chars_formati' std::format does not work on x86_64-w64-mingw32

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107693

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>:

https://gcc.gnu.org/g:ce86d9678b7f3d914133a035fbf8088504d8bad8

commit r13-4059-gce86d9678b7f3d914133a035fbf8088504d8bad8
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Tue Nov 15 13:44:38 2022 +0000

    libstdc++: Fix detection of std::format support for __float128 [PR107693]

    std::format gives linker errors on targets that define __float128 but
    do not support using it with std::to_chars. This improves the handling
    of 128-bit flaoting-point types so they are disabled if unsupportable.

    libstdc++-v3/ChangeLog:

            PR libstdc++/107693
            * include/std/format (_GLIBCXX_FORMAT_F128): Define to 2 when
            basic_format_arg needs to use its _M_f128 member.
            (__extended_floating_point, __floating_point): Replace with ...
            (__formattable_floating_point): New concept.
            * testsuite/std/format/functions/format.cc: Check whether
            __float128 is supported. Also test _Float128.