[Bug libstdc++/104883] <system_error> should define all std::errc enumerators

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104883

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:c86ac1a463f97554b1df9ef8a3e18573ef115e35

commit r11-10578-gc86ac1a463f97554b1df9ef8a3e18573ef115e35
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jan 31 22:16:31 2023 +0000

    libstdc++: Fix build failures for avr

    The avr-libc <errno.h> does not define EOVERFLOW, which means that
    std::errc::value_too_large is not defined, and so <charconv> cannot be
    compiled. Define value_too_large for avr with a value that does not
    clash with any that is defined in <errno.h>. This is a kluge to fix
    bootstrap for avr; it can be removed after PR libstdc++/104883 is
    resolved.

    The avr-libc <errno.h> fails to meet the C and POSIX requirements that
    each error macro has a distinct integral value, and is usable in #if
    directives. Add a special case for avr to system_error.cc so that only
    the valid errors are recognized. Also disable the errno checks in
    std::filesystem::remove_all that assume a meaningful value for errno.

    On avr-libc <unistd.h> exists but does not define the POSIX functions
    needed by std::filesystem, so _GLIBCXX_HAVE_UNISTD_H is not sufficient
    to check for basic POSIX APIs. Check !defined __AVR__ as well as
    _GLIBCXX_HAVE_UNISTD_H before using those functions. This is a kluge and
    we should really have a specific macro that says the required functions
    are available.

    libstdc++-v3/ChangeLog:

            * config/os/generic/error_constants.h (errc::value_too_large)
            [__AVR__]: Define.
            * src/c++11/system_error.cc
            (system_category::default_error_condition) [__AVR__]: Only match
            recognize values equal to EDOM, ERANGE, ENOSYS and EINTR.
            * src/c++17/fs_ops.cc (fs::current_path) [__AVR__]: Do not use
            getcwd.
            * src/filesystem/ops-common.h [__AVR__]: Do not use POSIX open,
            close etc.

    (cherry picked from commit 2d2e163d12f64a5e68f9e0381751ed9d5d6d3617)