[Bug c++/117966] [12/13/14/15 regression] constexpr std::span construction fails to compile with D_GLIBCXX_DEBUG

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117966

--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:c55e69d87caf8ec7c4a008b571f2232570255855

commit r13-9468-gc55e69d87caf8ec7c4a008b571f2232570255855
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Dec 9 17:35:24 2024 +0000

    libstdc++: Skip redundant assertions in std::span construction [PR117966]

    As PR c++/117966 shows, the Debug Mode checks cause a compilation error
    for a global constexpr std::span. Those debug checks are redundant when
    constructing from an array or a range, because we already know we have a
    valid range and we know its size. Instead of delegating to the
    std::span(contiguous_iterator, contiguous_iterator) constructor, just
    initialize the data members directly.

    libstdc++-v3/ChangeLog:

            PR libstdc++/117966
            * include/std/span (span(T (&)[N])): Do not delegate to
            constructor that performs redundant checks.
            (span(array<T, N>&), span(const array<T, N>&)): Likewise.
            (span(Range&&), span(const span<T, N>&)): Likewise.
            * testsuite/23_containers/span/117966.cc: New test.

    (cherry picked from commit e95bda027e0b81922c1bf44770674190bdf787e8)