Forbid unused `noqa` comments

[sobolevn]

Rule request

Thesis

We should raise a warning when noqa comment is unused. However, I am not sure that this is possible without patching flake8.

Reasoning

Consider this example:

some_variable = 12  # noqa: A001

A001 means that your name overrides some python builtin. But, it does not look like so. Or does it?

This kind of errors happen to have historical roots. At some point in time they were actually used, but then the code was refactored. But the comment was left untouched.

[sobolevn]

See https://github.com/snoack/flake8-per-file-ignores/blob/master/flake8_per_file_ignores.py#L61-L65

This is already implemented. We just need to copy this logic.

[sobolevn]

Related: https://github.com/asottile/yesqa

[sobolevn]

We can also warn about unused ignore= and per-file-ignores=

[maltevesper]

I think there is another related option: https://pypi.org/project/flake8-noqa/

[aleksey-sergey]

I think there is another related option: https://pypi.org/project/flake8-noqa/ It's a nice package indeed. Added it to one of my projects and it "just worked"!

[vnmabus]

I am really interested in this. It is also useful to remove the silencing of false positives when they are fixed.

[urtow]

@vnmabus May be just use flake8-noqa?