[Bug libstdc++/94681] New: filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[Bug libstdc++/94681] New: filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[valentin.david at codethink dot co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

            Bug ID: 94681
           Summary: filesystem::sysmlink_status using stat instead of
                    lstat when --disable-libstdcxx-filesystem-ts
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: valentin.david at codethink dot co.uk
  Target Milestone: ---

Created attachment 48321
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48321&action=edit
Proposed fix

std::filesystem::sysmlink_status follows symlinks when GCC has been configured
with --disable-libstdcxx-filesystem-ts, but it works fine when it has been
configured with --enable-libstdcxx-filesystem-ts.

The reason is that libstdc++-v3/src/c++17/fs_ops.cc includes
libstdc++-v3/src/filesystem/ops-common.h which has some requirements in the
configure script that are not executed.

In libstdc++-v3/acinclude.m4, GLIBCXX_CHECK_FILESYSTEM_DEPS is guarded by test
"$enable_libstdcxx_filesystem_ts = yes". But this should be run even if
enable_libstdcxx_filesystem_ts is "no" since
libstdc++-v3/src/filesystem/ops-common.h is used when
--disable-libstdcxx-filesystem-ts is used.

Removing this "if" fixed the issue for me.

While I have not tested master, I believe the issue is still there.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2020-04-21
     Ever confirmed|0                           |1
           Assignee|unassigned at gcc dot gnu.org      |redi at gcc dot gnu.org

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Oops, that configure option should have no impact on the std::filesystem
implementation.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch
   Target Milestone|---                         |9.4

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I'm not too concerned about the impact on people using the --disable option,
because the default for most targets is to enable it, and everything works.

But for systems where the default is --disable it means the std::filesystem
support is borked.

I think it's a bit too late to fix this for GCC 10.1 because it would enable
new code paths on systems where --disable is the default, and those are the
less well-tested targets. I don't want to break those right before we release
GCC 10.

So I'll fix this on master as soon as GCC 10.1 is released, and backport it for
10.2 and 9.4 later.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #3 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:90f7636bf8df50940e0f749af60a6b374a8f09b4

commit r11-2633-g90f7636bf8df50940e0f749af60a6b374a8f09b4
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 13:21:59 2020 +0100

    libstdc++: Make C++17 ignore --disable-libstdcxx-filesystem-ts [PR 94681]

    The configure switch should only affect the optional Filesystem TS, not
    the std::filesystem features of C++17.

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Do not depend on
            $enable_libstdcxx_filesystem_ts.
            * configure: Regenerate.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Only fixed on master so far.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[clyon at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

Christophe Lyon <clyon at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clyon at gcc dot gnu.org

--- Comment #5 from Christophe Lyon <clyon at gcc dot gnu.org> ---
The commit r11-2633 broke the build of libstdc++ on aarch64-none-elf. My build
logs say:
/tmp/7968837_9.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:
In function 'std::filesystem::__cxx11::path std::filesystem::read_symlink(const
std::filesystem::__cxx11::path&, std::error_code&)':
/tmp/7968837_9.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:1178:9:
error: '::lstat' has not been declared; did you mean
'std::filesystem::__gnu_posix::lstat'?
 1178 |   if (::lstat(p.c_str(), &st))
      |         ^~~~~
      |         std::filesystem::__gnu_posix::lstat
In file included from
/tmp/7968837_9.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/fs_ops.cc:58:
/tmp/7968837_9.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/libstdc++-v3/src/c++17/../filesystem/ops-common.h:131:14:
note: 'std::filesystem::__gnu_posix::lstat' declared here
  131 |   inline int lstat(const char* path, stat_type* buffer)
      |              ^~~~~
make[5]: *** [Makefile:572: fs_ops.lo] Error 1
make[5]: Leaving directory
'/tmp/7968837_9.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64_be-none-elf/gcc3/aarch64_be-none-elf/libstdc++-v3/src/c++17'
make[4]: *** [Makefile:732: all-recursive] Error 1

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Thanks, I thought this might reveal some new issues :-)

I'll fix it asap.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #7 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:5b065f0563262a0d6cd1fea8426913bfdd841301

commit r11-2638-g5b065f0563262a0d6cd1fea8426913bfdd841301
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 18:58:14 2020 +0100

    libstdc++: Fix build for targets without lstat [PR 94681]

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * src/c++17/fs_ops.cc (read_symlink): Use posix::lstat instead
            of calling ::lstat directly.
            * src/filesystem/ops.cc (read_symlink): Likewise.

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:4e00119c780f9bcd33181db4580754522f64c60e

commit r10-8783-g4e00119c780f9bcd33181db4580754522f64c60e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 13:21:59 2020 +0100

    libstdc++: Make C++17 ignore --disable-libstdcxx-filesystem-ts [PR 94681]

    The configure switch should only affect the optional Filesystem TS, not
    the std::filesystem features of C++17.

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Do not depend on
            $enable_libstdcxx_filesystem_ts.
            * configure: Regenerate.

    (cherry picked from commit 90f7636bf8df50940e0f749af60a6b374a8f09b4)

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:eef40b0037b90ff117322423fc297dc528285524

commit r10-8784-geef40b0037b90ff117322423fc297dc528285524
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 18:58:14 2020 +0100

    libstdc++: Fix build for targets without lstat [PR 94681]

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * src/c++17/fs_ops.cc (read_symlink): Use posix::lstat instead
            of calling ::lstat directly.
            * src/filesystem/ops.cc (read_symlink): Likewise.

    (cherry picked from commit 5b065f0563262a0d6cd1fea8426913bfdd841301)

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #10 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:3ec14c9a49aa6c35609eaf04f74132e28a2dc9d5

commit r9-8926-g3ec14c9a49aa6c35609eaf04f74132e28a2dc9d5
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 13:21:59 2020 +0100

    libstdc++: Make C++17 ignore --disable-libstdcxx-filesystem-ts [PR 94681]

    The configure switch should only affect the optional Filesystem TS, not
    the std::filesystem features of C++17.

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Do not depend on
            $enable_libstdcxx_filesystem_ts.
            * configure: Regenerate.

    (cherry picked from commit 90f7636bf8df50940e0f749af60a6b374a8f09b4)

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #11 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:90f845adff0379682080a1253d477e0b621768b7

commit r9-8927-g90f845adff0379682080a1253d477e0b621768b7
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Aug 10 18:58:14 2020 +0100

    libstdc++: Fix build for targets without lstat [PR 94681]

    libstdc++-v3/ChangeLog:

            PR libstdc++/94681
            * src/c++17/fs_ops.cc (read_symlink): Use posix::lstat instead
            of calling ::lstat directly.
            * src/filesystem/ops.cc (read_symlink): Likewise.

    (cherry picked from commit 5b065f0563262a0d6cd1fea8426913bfdd841301)

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for 9.4 and 10.3

[Bug libstdc++/94681] filesystem::sysmlink_status using stat instead of lstat when --disable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94681

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> ---
.