On Tue, 1 Feb 2022 at 22:00, Jonathan Wakely via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> The standard requires directory iterators to become equal to the end
> iterator value if they report an error. Some members functions of
> filesystem::recursive_directory_iterator fail to do that.
>
> libstdc++-v3/ChangeLog:
>
>         * src/c++17/fs_dir.cc (recursive_directory_iterator::increment):
>         Reset state to past-the-end iterator on error.
>         (fs::recursive_directory_iterator::pop(error_code&)): Likewise.
>         (fs::recursive_directory_iterator::pop()): Check _M_dirs before
>         it might get reset.
>         * src/filesystem/dir.cc (recursive_directory_iterator): Likewise,
>         for the TS implementation.
>         * testsuite/27_io/filesystem/iterators/error_reporting.cc: New test.
>         * testsuite/experimental/filesystem/iterators/error_reporting.cc: New test.
> ---
>  libstdc++-v3/src/c++17/fs_dir.cc              |  12 +-
>  libstdc++-v3/src/filesystem/dir.cc            |  12 +-
>  .../filesystem/iterators/error_reporting.cc   | 135 +++++++++++++++++
>  .../filesystem/iterators/error_reporting.cc   | 136 ++++++++++++++++++
>  4 files changed, 291 insertions(+), 4 deletions(-)
>  create mode 100644 libstdc++-v3/testsuite/27_io/filesystem/iterators/error_reporting.cc
>  create mode 100644 libstdc++-v3/testsuite/experimental/filesystem/iterators/error_reporting.cc
>
[...]
> +
> +extern "C" struct dirent* readdir(DIR*)
> +{
> +  switch (choice)
> +  {
> +  case 1:
> +    global_dirent.d_ino = 999;
> +    global_dirent.d_type = DT_REG;

These new tests should not use the d_type member unless it's actually
present on the OS. Fixed by the attached patch.

Tested x86_64-linux and mingw-w64, pushed to trunk.