Should unions including Any trigger ANN401 (or some other rule)?

[bersbersbers]

from typing import Any

def fun_ann401(abc: Any) -> None:
    print(abc)

def fun_no_error(abc: Any | None = None) -> None:
    print(abc)

gives

bug.py:4:21: ANN401 Dynamically typed expressions (typing.Any) are disallowed in abc

I wonder why that error is not also emitted for fun_no_error. Any | None is at least as undefined as Any is.

Another option would be to add a new rule that says

Any | Foo is redundant and should be replaced by Any.

[charliermarsh]

I think it should be included, yeah.

[charliermarsh]

Maybe we can reuse the logic that @dhruvmanila added for implicit optionals.

[dhruvmanila]

Maybe we can reuse the logic that @dhruvmanila added for implicit optionals.

If I understand correctly, do you mean to check if there's typing.Any instead of None in the TypingTarget? Or, do you just mean to use the | union iterator to check if there's Any in it?

[charliermarsh]

The latter! Does that make sense?

[dhruvmanila]

It does but then Union[Any, None] (which is same as Any | None) won't be triggered.

[dhruvmanila]

Actually, this then brings up the question if we should look for Any in other places as well (Optional[Any]).

I believe the main question would be "does this type resolve to Any"?

[charliermarsh]

Err, sorry, I may have misunderstood your question. We're just looking to understand whether the type resolves to Any, I think.

[dhruvmanila]

Right, then I believe the following cases should also be considered although the original plugin doesn't support them.

• Any | ...
• Union[Any, ...]
• Optional[Any]
• Annotated[<any of the above variants>, ...]
• Forward references?

Does this make sense?

I don't think Any in container types (e.g., list[Any]) should be considered, right?

[charliermarsh]

Yes, agreed.

[dhruvmanila]

It should be simple enough to extract out the logic from implicit-optional check and add another method to check for Any.