[Bug libstdc++/115308] std::experimental::simd<char> is not convertible to NEON intrinsic type with Clang

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115308

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Matthias Kretz
<mkretz@gcc.gnu.org>:

https://gcc.gnu.org/g:ef2169090d0868e4718c2ebf25365aaa52c22139

commit r13-8841-gef2169090d0868e4718c2ebf25365aaa52c22139
Author: Matthias Kretz <m.kretz@gsi.de>
Date:   Mon Jun 3 12:02:07 2024 +0200

    libstdc++: Fix simd<char> conversion for -fno-signed-char for Clang

    The special case for Clang in the trait producing a signed integer type
    lead to the trait returning 'char' where it should have been 'signed
    char'. This workaround was introduced because on Clang the return type
    of vector compares was not convertible to '_SimdWrapper<
    __int_for_sizeof_t<...' unless '__int_for_sizeof_t<char>' was an alias
    for 'char'. In order to not rewrite the complete mask type code (there
    is code scattered around the implementation assuming signed integers),
    this needs to be 'signed char'; so the special case for Clang needs to
    be removed.
    The conversion issue is now solved in _SimdWrapper, which now
    additionally allows conversion from vector types with compatible
    integral type.

    Signed-off-by: Matthias Kretz <m.kretz@gsi.de>

    libstdc++-v3/ChangeLog:

            PR libstdc++/115308
            * include/experimental/bits/simd.h (__int_for_sizeof): Remove
            special cases for __clang__.
            (_SimdWrapper): Change constructor overload set to allow
            conversion from vector types with integral conversions via bit
            reinterpretation.

    (cherry picked from commit 8e36cf4c5c9140915d0019999db132a900b48037)