[Bug libstdc++/93972] ranges::lexicographical_compare gives wrong answer for signed integers

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93972

--- 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:d112e173ea093f55a16a14b26ef65088381ee09c

commit r10-6975-gd112e173ea093f55a16a14b26ef65088381ee09c
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Mar 2 17:03:28 2020 +0000

    libstdc++: Fix std::lexicographic_compare for unsigned char (PR 93972)

    The new 25_algorithms/lexicographical_compare/93972.cc test fails on
    targets where char is unsigned, revealing an existing regression with
    the std::__memcmp helper that had gone unnoticed in
    std::lexicographical_compare. When comparing char and unsigned char, the
    memcmp optimisation is enabled, but the new std::__memcmp function fails
    to compile for mismatched types.

        PR libstdc++/93972
        * include/bits/stl_algobase.h (__memcmp): Allow pointer types to
        differ.
        * testsuite/25_algorithms/lexicographical_compare/uchar.cc: New test.