pybind11 filesystem: import os is missing in files with os.PathLike in stubs

[dyollb]

I am using the pybind/stl/filesystem.h support to add pathlib.Path support.
In the stubs I get something like this:

class ImporterBase:
    """
    Base class for all importers.
    """
    def Import(self, file_path: os.PathLike | str | bytes) -> list[Entity]:
        """
        Imports a model from a file into the active model.
        """

However, the module os is not imported at the top of the file. Is this a pybind11 bug or a stubgen bug?
Where would this be processed (I would be willing to provide a PR)?

Would it help to provide a PR with a failing test?

[gentlegiantJGC]

This is an issue with how pybind11-stubgen handles unions (and other types with nested types).
I fixed a similar issue in #272 where nested types from the same module were not contracted.

This is the class that handles missing imports. You will need to modify it in a similar way.
https://github.com/sizmailov/pybind11-stubgen/blob/ac46c10e229f1fc570600a14a644238b86ae4f99/pybind11_stubgen/parser/mixins/fix.py#L85C1-L200C20

Specifically these two function calls
https://github.com/sizmailov/pybind11-stubgen/blob/ac46c10e229f1fc570600a14a644238b86ae4f99/pybind11_stubgen/parser/mixins/fix.py#L103-L104
https://github.com/sizmailov/pybind11-stubgen/blob/ac46c10e229f1fc570600a14a644238b86ae4f99/pybind11_stubgen/parser/mixins/fix.py#L151-L152

[sarlinpe]

I believe that there is a simpler fix - see parse.py in #263

https://github.com/sizmailov/pybind11-stubgen/pull/263/files#diff-096ed72bdab4fe6de150b5717c6da4ec1f1d8f721bb8ac2a30f6f87db6a3cf53

[gentlegiantJGC]

That is a much better solution. It fixes both of our issues.

[ax3l]

Combined your tests in #272 and simple fix from #263 into #280

(I assume the size of changes in #263 need a longer review)