[Bug libstdc++/123180] [16 Regression] -Wnonnull with std::ranges::stable_sort

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123180

--- Comment #4 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:630c1bfbb5bc3ba9fafca5e97096263ab8f0a04b

commit r16-6246-g630c1bfbb5bc3ba9fafca5e97096263ab8f0a04b
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Dec 18 10:38:31 2025 +0000

    libstdc++: Fix ranges::stable_sort handling of null buffer [PR123180]

    The logic of the null pointer check got reversed when converting the
    std::stable_sort code for ranges::stable_sort.

    libstdc++-v3/ChangeLog:

            PR libstdc++/123180
            * include/bits/ranges_algo.h (__stable_sort_fn::operator()): Fix
            sense of null check. Replace typedef with alias-declaration.
            * testsuite/25_algorithms/stable_sort/123180.cc: New test.

    Reviewed-by: Patrick Palka <ppalka@redhat.com>