[Bug libstdc++/110352] [C++26] P2630R4 submdspan

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110352

--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tomasz Kaminski <tkaminsk@gcc.gnu.org>:

https://gcc.gnu.org/g:558ab7b6389e2dc8dcd5e9da2c982e79a3cdd42c

commit r16-5997-g558ab7b6389e2dc8dcd5e9da2c982e79a3cdd42c
Author: Luc Grosheintz <luc.grosheintz@gmail.com>
Date:   Mon Dec 8 21:23:44 2025 +0100

    libstdc++: Implement submdspan_mapping for layout_left_padded. [PR110352]

    Implements submdspan for layout_left_padded as described in P3663.

            PR libstdc++/110352

    libstdc++-v3/ChangeLog:

            * include/std/mdspan (__mdspan::__is_padded_mapping): Define.
            (__mdspan::_SubMdspanMapping): Add _Padded template parameter.
            (__mdspan::_SubMdspanMapping<_LayoutSide::__left, true>): Define.
            (__mdspan::__submdspan_mapping_impl): Updated _Trait alias.
            (layout_left_padded::submdspan_mapping): New friend method.
            * testsuite/23_containers/mdspan/layout_traits.h
            (LayoutTraits::layout_same_padded): New template type alias.
            *
testsuite/23_containers/mdspan/submdspan/selections/left_padded.cc:
            Instantiate tests for layout_left_padded.
            * testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc:
            Ditto.

    Reviewed-by: Tomasz KamiÅski <tkaminsk@redhat.com>
    Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>