[Bug libstdc++/115668] Cannot format chrono::duration<unsigned>

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115668

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:dafa750c8a6f0a088677871bfaad054881737ab1

commit r15-1690-gdafa750c8a6f0a088677871bfaad054881737ab1
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Jun 26 20:22:54 2024 +0100

    libstdc++: Fix std::format for chrono::duration with unsigned rep
[PR115668]

    Using std::chrono::abs is only valid if numeric_limits<rep>::is_signed
    is true, so using it unconditionally made it ill-formed to format a
    duration with an unsigned rep.

    The duration formatter might as negate the duration itself instead of
    using chrono::abs, because it already needs to check for a negative
    value.

    libstdc++-v3/ChangeLog:

            PR libstdc++/115668
            * include/bits/chrono_io.h (formatter<duration<R,P, C>::format):
            Do not use chrono::abs.
            * testsuite/20_util/duration/io.cc: Check formatting a duration
            with unsigned rep.