[Bug libstdc++/94242] filesystem::path::generic_string() only works with std::allocator

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94242

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:e7406c364496dae51ef294b5720923fe4a1dfccb

commit r9-8792-ge7406c364496dae51ef294b5720923fe4a1dfccb
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Sat Mar 21 21:51:07 2020 +0000

    libstdc++: Fix path::generic_string allocator handling (PR 94242)

    It's not possible to construct a path::string_type from an allocator of
    a different type. Create the correct specialization of basic_string, and
    adjust path::_S_str_convert to use a basic_string_view so that it is
    independent of the allocator type.

            PR libstdc++/94242
            * include/bits/fs_path.h (path::_S_str_convert): Replace first
            parameter with basic_string_view so that strings with different
            allocators can be accepted.
            (path::generic_string<C,T,A>()): Use basic_string object that uses
the
            right allocator type.
            * testsuite/27_io/filesystem/path/generic/94242.cc: New test.
            * testsuite/27_io/filesystem/path/generic/generic_string.cc:
Improve
            test coverage.

    (cherry picked from commit 9fc985118d9f5014afc1caf32a411ee5803fba61)