Enabling specific preview rules

[adrinjalali]

Our usecase scikit-learn/scikit-learn#29477 is that we'd like to enable CPY001. Since it's a preview rule, one needs to enable preview mode.

However, preview mode enables many other rules which don't work as intended on our repo, give false positives, ...

That's why I looked into enabling preview rules only explicitly. However, when one does something like select = ["E", "F", "W", "I", "CPY001"] in the configuration, everything under those categories are enabled, regardless of them being in preview mode or not.

I'd argue that the above select doesn't really explicitly select those preview rules under E, F, ..., however, they're selected.

This is related to #7434, and I think explicit-preview-rules introduced in #7390 somewhat intends to fix the issue, but in this case it doesn't.

What should one do in this case?

In effect, I think I'd expect this config:

[tool.ruff.lint]
# This enables us to use CPY001: copyright header check
preview = true
# This enables us to use the explicit preview rules that we want only
explicit-preview-rules = true
# all rules can be found here: https://beta.ruff.rs/docs/rules/
select = ["E", "F", "W", "I", "CPY001"]

to only include stable rules under those categories, and enable CPY001 on top of them, and no other preview rule should be enabled.

[MichaReiser]

Thanks for the detailed write up.

However, preview mode enables many other rules which don't work as intended on our repo, give false positives, ...

This is somewhat intentional because we want to encourage users to give feedback on preview rules. Whether we promote a rule to stable depends on the feedback we receive from users. Without feedback, we'll end up promoting a rule that then creates a lot of churn downstream.

This is related to #7434, and I think explicit-preview-rules introduced in #7390 somewhat intends to fix the issue, but in this case it doesn't.

Could you explain which part isn't working for you?

I tried to reproduce your setup by enabling the same rules as in your example and using explcit-preview-rules (playground). To me it is working as expected because Ruff doesn't report an error for the preview rule E201 that flags the whitespace after [ .

I can set explicit-preview-rules to false and the E201 violation then gets reported (playground)

[adrinjalali]

So on scikit-learn, adding

preview = true
# This enables us to use the explicit preview rules that we want only
explicit-preview-rules = true

results in:

Found 364 errors.
No fixes available (308 hidden fixes can be enabled with the `--unsafe-fixes` option).

while on main, we get:

Found 14 errors.

$ ruff --version
ruff 0.5.1

Here are the outputs of ruff check . on the repo with and without the preview config added:

stable.txt

preview.txt

[MichaReiser]

Thanks, I now see what's happening. What you're experience isn't that it enables additional preview-only rules, but that you see new violations because of some preview-only changes to stable rules.

We don't support enabling preview functionality for specific rules only. Enabling preview mode enables the preview functionality for all rules (if they have any). explicit-preview-rules only controls if preview-only rules should be enabled when using a selector like E.

[adrinjalali]

Oh now I understand. However, that puts us in a weird position, because:

• we need preview to enable CPY001
• that enables preview sub-rules of already active rules
• those give a lot of false positives / things we don't want to change
• we end up outright disabling those rules
• those rules end up not detecting legit things now since they're completely disabled

I feel like there should be a middle ground there? I hope this makes sense.

[zanieb]

If those rule changes are giving you false positives in preview mode, I'd highly recommend opening issues because the behavior is likely to become stable soon.

Unfortunately we don't have enough bandwidth to manage different preview modes, that's why we have a single global flag. explicit-preview-rules is already the compromise.

An option here is to allow explicit selection of preview rules without enabling preview mode. We'd probably need to display a warning that the rule is in preview, though.

[jaraco]

Not sure if this is the same issue when dealing with formatting.

Related to this issue, the "single flag to rule them all" has caused confusion and consternation. My projects adopted the setting in order to make "quote-style=preserve" work for compatibility when migrating from black, but that caused "hugged parenthesis" to be adopted implicitly. Later, when quote-style=preserve graduated to stable, we tried to remove the setting but that would roll back other behaviors.

In my projects, I'm opting to have "preview=true" by default (and the uncertainty that will bring), but at least that will allow the projects to continue to shift left (work at head).

I realize it's difficult to manage feature-specific flags, but just be aware that the user experience is muddled by the shifting meaning of this flag over time and releases.