MAINT: py3k: remove os.fspath and os.PathLike backports

[zer0link]

Related to #15986 .
Chain exceptions in "py3k.py" corresponding to exceptions on line 173 as mentioned in this comment.

[mattip]

Could you show an example of how this exception now looks? It should be easy to call this code with an object that trips it.

[eric-wieser]

This entire function is completely unreachable - we should just remove it.

[zer0link]

The error stack basically looks the same as before:

  File "test_py3k.py", line 6, in <module>
    test_obj = os_fspath({'test':'test'})
TypeError: expected str, bytes or os.PathLike object, not dict```

[zer0link]

This entire function is completely unreachable - we should just remove it.

Should I remove the function instead?

[eric-wieser]

The condition if sys.version_info[:2] >= (3, 6): is always true since we don't support python 3.5, so please do - everything in that else can go.

[zer0link]

The condition if sys.version_info[:2] >= (3, 6): is always true since we don't support python 3.5, so please do - everything in that else can go.

Updated based on comment

[zer0link]

Hi, I am having difficulties trying to run the failing tests locally,
is there a document I can refer?

[rossbar]

is there a document I can refer?

You may find this doc useful: https://numpy.org/doc/stable/dev/development_environment.html#running-tests

[eric-wieser]

The failures are unrelated, let's try rerunning

[eric-wieser]

Thanks @zer0link!

[eric-wieser]

If you're looking to make another contribution, it would be great if we could find all the places that use np.compat.os_PathLike and replace them with os.PathLike.

[zer0link]

Thanks @eric-wieser , was trying to debug the issue for some time now