Is there a way to lint for and prevent _ is False (identity comparison)? (stricter E712)

[jbcpollak]

I would like to enforce that checks for True/False identity always take the form if _ rather than if _ is True. E712 allows the is form. Is there an enhanced check I could do?

[MichaReiser]

I don't think such a rule exists today. @AlexWaygood any thoughts?

[AlexWaygood]

E712 allows _ is False comparisons to avoid false positives, since there are some occasions when you do want to check that something is exactly the False constant rather than just something that has a false boolean value. However, I agree that those occasions are pretty rare, so I think it's reasonable to want a stricter check.

Maybe instead of adding a new rule, we could just make E712 configurable. The default could be the current behaviour (lenient, avoids false positives), but we could have a setting that makes it stricter and also disallows identity comparisons to the True and False constants.

[jbcpollak]

if a new or configurable E712 is an option, it seems like it would address #4560 as well.

[jbcpollak]

That would be great - I'd be happy with either a new rule or making E712 configurable.

Is their precedent for configurable rules in Python? It's common in JS linting tools but I don't think I've seen it in Python before.

[AlexWaygood]

We have quite a few configurable rules in Ruff. Most of our flake8-pytest-style rules are configurable, and for most of our pydocstyle rules you can specify the docstring convention you want to enforce, etc.

[jbcpollak]

Ah. I hadn't noticed. Either way works for me!