filecmp and tempfile can handle pathlib.Path

[scivision]

filecmp can handle pathlib.Path, including:

• filecmp.cmp
• filecmp.cmpfiles
• filecmp.dircmp

Before this patch, doing something like

from pathlib import Path
import filecmp

filecmp.dircmp(Path('/tmp'), '/tmp')

would work fine when executed, but would give mypy errors like

error: Value of type variable "AnyStr" of "dircmp" cannot be "Path"

After this change, type checking works as expected

[scivision]

Hmm, I think this may need to be split into stdlib/3.6/filecmp.pyi.

Do the maintainers concur?

The other option per https://github.com/python/typeshed/blob/master/CONTRIBUTING.md#stub-versioning would be to use if statements inside the existing filecmp.pyi.

[gvanrossum]

I would use if sys.version_info >= (3, 6).

[scivision]

OK I believe the fixes are ready to go.

[JelleZijlstra]

Because this uses AnyStr, we should ideally also use a type variable in the PathLike case (so PathLike[AnyStr]). But this sort of things tends to run into mypy bugs sometimes. We should check a few cases like these:

• cmpfiles(bytes, bytes) returns Tuple[List[bytes], ...]
• cmpfiles(str, str) returns Tuple[List[str], ...]
• cmpfiles(PathLike[str], PathLike[str]) returns Tuple[List[str], ...]
• cmpfiles(PathLike[str], bytes) is an error

You can check these in mypy by using reveal_type.

[JelleZijlstra]

Same here, we should use PathLike[AnyStr] but should verify it actually works.

Also, do the ignore and hide parameters also accept paths?

[JelleZijlstra]

Most of these functions have the same issue with AnyStr.

[srittau]

@scivision Are you still interested in this pull request?

[scivision]

Hi @srittau it seems like the fix grew bigger. I don't have much time lately so I have just been using type: ignore

[srittau]

Thank you for your work on this. I am closing this PR for now. Please reopen it or open a new PR if you wish to finish it.