[Bug libstdc++/94498] std::basic_string_view::copy not qualified constexpr in c++2a

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94498

--- Comment #1 from CVS 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:b696698767ba45b4d61a93205167e2f1f744d3f1

commit r10-7569-gb696698767ba45b4d61a93205167e2f1f744d3f1
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Apr 6 18:30:53 2020 +0100

    libstdc++: Make string_view::copy usable in constant expressions (PR 94498)

            PR libstdc++/94498
            * include/bits/char_traits.h (__gnu_cxx::char_traits::move): Make
it
            usable in constant expressions for C++20.
            (__gnu_cxx::char_traits::copy, __gnu_cxx::char_traits::assign): Add
            _GLIBCXX20_CONSTEXPR.
            (std::char_traits<char>, std::char_traits<wchar_t>)
            (std::char_traits<char8_t>): Make move, copy and assign usable in
            constant expressions for C++20.
            (std::char_traits<char16_t>, std::char_traits<char32_t>): Make move
            and copy usable in constant expressions for C++20.
            * include/std/string_view (basic_string_view::copy): Add
            _GLIBCXX20_CONSTEXPR.
            * testsuite/21_strings/basic_string_view/operations/copy/char/
            constexpr.cc: New test.
            * testsuite/21_strings/basic_string_view/operations/copy/wchar_t/
            constexpr.cc: New test.