Implement autoflake

[charliermarsh]

• Remove unused imports (F401)
• Remove duplicate keys (F601)
• Remove unused variables (F841)
• Expand star imports (F403)
• Useless pass statements

[charliermarsh]

I'm hesitant to add autofix for F601 and F403, because the right behavior isn't clear, and automatically fixing them is very likely to cause problems.

I'd be open to autofixing F601 in the case that the values are duplicated too.

[charliermarsh]

Happy with this for now. I'm not planning to do star imports with the current approach, and we already do some subset of pass statements.

[cclauss]

What about trying the https://github.com/asmeurer/removestar approach for creating an F403 fixer?

[sanmai-NL]

@charliermarsh

The last item

Useless pass statements

is already implemented as https://beta.ruff.rs/docs/rules/unnecessary-pass/

[RobertDeRose]

Why is F841 considered unsafe?

Example

ruff check --fix --config pyproject.toml
gpio/models/pin.py:
  159:9 F841 Local variable `unused` is assigned to but never used

Found 1 error.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).

This was a test to see if the behavior of Ruff is the same as autoflake, and it is not. autoflake removes it, Ruff requires the addition of --unsafe-fixes

Ruff version: ruff 0.4.4 (3e8878a 2024-05-09)