Support range in required-version setting

[kujenga]

Currently, it appears that the required-version [1] setting allows just a single specific version to be specified. When a version of ruff is present that differs from this version, the ruff tool errors, preventing checks from running.

The ask here is to allow range syntax, e.g. >=, ~, etc., or perhaps treat the required-version as a minimum similar to target-version, so that ruff does not fail to run in the scenario that e.g. a developer upgrades ruff in their environment but is working within a repo that wants to ensure that everyone is on some minimum version of ruff.

$ ruff --version
ruff 0.3.0

$ cat ruff.toml
required-version = "0.2.2"

$ ruff check ./src/example/file.py
ruff failed
  Cause: Required version `0.2.2` does not match the running version `0.3.0`

[1] https://docs.astral.sh/ruff/settings/#required-version

[charliermarsh]

I think it'd be reasonable to support >= here.

[charliermarsh]

(We just need to make it backwards-compatible such that "0.2.2" means "==0.2.2".)

[MichaReiser]

I think it'd be reasonable to support >= here.

I think we would need to support a full semver syntax similar to package.json engines or it might be surprising that e.g. `<= isn't supported which, IMO, is entirely reasonable too

A first step before a PR is to spec out the exact behavior of that field with the supported syntax to avoid long discussions on the PR

[charliermarsh]

Correct, that’s what I meant — we should use Python’s PEP 440 and PEP 508 specifiers since they’re already native, standardized, used in the same TOML file, and we have parsers for them. I don’t think there needs to be any more decision-making than that, personally!

[MichaReiser]

Seems reasonable, although PEP440 is probably more flexible than what we need (local versions). PEP508 seems unrelated because we don't need a name portion.

[charliermarsh]

👍 The gist of it is: it should just function identically to requires-python which is a standardized field that we already parse and support (see: crates/ruff_workspace/src/pyproject.rs).