Flag unused imports even with redefinition

[charliermarsh]

Given this code:

import os
import os

We return:

Found 1 error(s).
foo.py:2:1: F401 `os` imported but unused

Flake8 does this:

foo.py:2:1: F811 redefinition of unused 'os' from line 1
foo.py:2:1: F401 'os' imported but unused

My preference would be:

Found 2 error(s).
foo.py:1:1: F401 `os` imported but unused
foo.py:2:1: F401 `os` imported but unused

[Cxxshyy]

hi im fairly new to rust but can have a go at this so can you first tell me what file handle this and ill take a look

[charliermarsh]

@Cxxshyy - Awesome! I marked this as good first issue a few weeks back but I think it may be deceptively tricky. (It requires some extra book-keeping to understand when an import "redefines" another import, since you can have imports split across if-else blocks and so on.)

If you're looking for a place to contribute, a good starting point might be to take a rule you like from flake8-bugbear and add it to Ruff (#389). I wrote some instructions on a similar issue in here that would be helpful for understanding how to add a new check. Does that look interesting to you?

[Cxxshyy]

yes that looks interesting ill have a look at this tomorrow

[charliermarsh]

Cool, don't hesitate to ask questions, I'd love to be helpful.

[Cxxshyy]

will do thanks

[charliermarsh]

This got resolved when we added the redefined-while-unused checks.