[PATCH 2/2] PR libstdc++/86756 Move rest of std::filesystem to libstdc++.so

[Jonathan Wakely]

On 07/01/19 10:24 +0100, Christophe Lyon wrote:
>Hi Jonathan
>
>On Sun, 6 Jan 2019 at 23:37, Jonathan Wakely <jwakely@redhat.com> wrote:
>>
>> Move std::filesystem directory iterators and operations from
>> libstdc++fs.a to main libstdc++ library. These components have many
>> dependencies on OS support, which is not available on all targets. Some
>> additional autoconf checks and conditional compilation is needed to
>> ensure the files will build for all targets. Previously this code was
>> not compiled without --enable-libstdcxx-filesystem-ts but the C++17
>> components should be available for all hosted builds.
>>
>> The tests for these components no longer need to link to libstdc++fs.a,
>> but are not expected to pass on all targets. To avoid numerous failures
>> on targets which are not expected to pass the tests (due to missing OS
>> functionality) leave the dg-require-filesystem-ts directives in place
>> for now. This will ensure the tests only run for builds where the
>> filesystem-ts library is built, which presumably means some level of OS
>> support is present.
>>
>>
>> Tested x86_64-linux (old/new string ABIs, 32/64 bit), x86_64-w64-mingw32.
>>
>> Committed to trunk.
>>
>
>After this commit (r267616), I've noticed build failures for my
>newlib-based toolchains:
>aarch64-elf, arm-eabi:
>
>In file included from
>/tmp/5241593_7.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:57:
>/tmp/5241593_7.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/../filesystem/ops-common.h:142:11:
>error: '::truncate' has not been declared
>  142 |   using ::truncate;
>      |           ^~~~~~~~
>/tmp/5241593_7.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:
>In function 'void std::filesystem::resize_file(const
>std::filesystem::__cxx11::path&, uintmax_t, std::error_code&)':
>/tmp/5241593_7.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:1274:19:
>error: 'truncate' is not a member of 'posix'
> 1274 |   else if (posix::truncate(p.c_str(), size))
>      |                   ^~~~~~~~
>make[5]: *** [fs_ops.lo] Error 1
>
>I'm not sure if there's an obvious fix? Note that I'm using a rather
>old newlib version, if that matters.

That's probably the reason, as I didn't see this in my tests with
newlib builds.

The fix is to add yet another autoconf check and guard the uses of
truncate with a _GLIBCXX_USE_TRUNCATE macro. I'll do that now ...