[Bug libstdc++/59769] please add ios_base::__noreplace

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59769

--- Comment #5 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:a219139e986a4200a9105d7c1fa63735d2945994

commit r12-5878-ga219139e986a4200a9105d7c1fa63735d2945994
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Dec 8 20:58:11 2021 +0000

    libstdc++: Implement std::ios_base::noreplace for C++23 [PR59769]

    This implements my P2467R0 proposal to support opening an fstream in
    exclusive mode. The new constant is also supported pre-C++23 as
    std::ios_base::__noreplace.

    This proposal hasn't been approved for C++23 yet, but I am confident it
    will be, as this is restoring a feture found in pre-ISO C++ iostreams
    implementations (and still present in the MSVC library as _Noreplace).
    If the proposal fails for C++23 we can remove the ios::noreplace
    name and just keep ios::__noreplace as an extension.

    libstdc++-v3/ChangeLog:

            PR libstdc++/59769
            * config/io/basic_file_stdio.cc (fopen_mode): Add support for
            exclusive mode.
            * include/bits/ios_base.h (_S_noreplace): Define new enumerator.
            (ios_base::__noreplace): Define.
            (ios_base::noreplace): Define for C++23.
            * include/std/version (__cpp_lib_ios_noreplace): Define.
            * testsuite/27_io/basic_ofstream/open/char/noreplace.cc: New test.
            * testsuite/27_io/basic_ofstream/open/wchar_t/noreplace.cc: New
test.