Check for unused imports

[srittau]

A check that knows the special import handling in stubs. E.g.:

from x import a, b, c as c

x: b

This should complain about a being unused, but not b or c.

[JelleZijlstra]

If there's an existing flake8 check or plugin that does this, it might just be a matter of adding the right incantations so that that check covers stub files.

[JelleZijlstra]

In typeshed we now get unused import checking from Pyright. I suppose it's still useful for flake8 to do it too (e.g. for other stub projects that don't support Pyright), but it feels low priority.

[Zeckie]

Link to some related issues

• Ignore reexports in .pyi files for F401 pyflakes#474
• Linter for unused imports python/typeshed#3322