Missing pyupgrade errors (UP006, UP035)

[rademacher-p]

Hi, I seem to be missing pyupgrade errors for Python 3.11 and Ruff 0.1.5. Reproduce w/ ruff --isolated --select UP file.py on a fresh venv. This is all from the CLI, no pyproject.toml.

# file.py
from typing import Type

foo = Type[list]

I ❤️ ruff, thanks in advance for any help!

[charliermarsh]

Thank you for the kind words!

I think this is a result of #3215 -- we stopped rewriting annotations that are used at runtime (roughly, on the right-hand side of an expression) because it can change behavior. #4843 has some more information. I think we actually can rewrite these in some but not all scenarios. In other words, our current approach is probably too conservative.

[charliermarsh]

I think it's always safe to perform these rewrites for UP006 (like List to list, assuming you're on a supported Python version).

It's probably not always safe to perform these rewrites for UP007 (which converts Union[int, str] to int | str).

[NeilGirdhar]

I think you should write this as a type alias:

foo: TypeAlias = Type[list]  # Python < 3.12
type foo = type[list]  # Python >= 3.12

And then would it be possible for Ruff to make the transformation? Are right-hand-sides of type aliases okay?

[rademacher-p]

Aside from the issues with autofix, is there a reason not to provide the deprecation inspection?

[charliermarsh]

The only reason is to ensure we're not introducing false positives. So it'd be nice to make sure we have a sense for where this is and isn't safe prior to enabling the check for runtime annotations.

[charliermarsh]

Oh hmm, I'm actually noticing that if your Python version is set correctly, we do flag and fix this: https://play.ruff.rs/526e6c64-b8da-4cd5-8dcd-68ee71a6f886

Do you have your --target-version configured to Python 3.11?

[rademacher-p]

@charliermarsh No, I did not! Should have had that in my config (actually, should just up my project.requires-python) 😮 Adding this option gives me the pyupgrade errors - feel free to close, if you're ready 👍

[charliermarsh]

Awesome, thanks @rademacher-p! Sorry for the confusion but glad to resolve.