Allow "reportUnusedDisableDirectives" option to "error"

[obweger]

The version of ESLint you are using.

6.8.0

The problem you want to solve.

I'd like to prevent (i.e., error on) unused directives via my configuration (rather than the CLI).

Your take on the correct solution to problem.

I can error on unused directives via --report-unused-disable-directives. However, for errors to be shown in the IDE, it would be easier to allow the reportUnusedDisableDirectives configuration option to be set to error. Currently, it can only be set to true, which translates to warn.

Are you willing to submit a pull request to implement this change?

Yes.

[kaicataldo]

I understand why this would be useful. The current design is intentional, however. If we allowed for errors to be reported with reportUnusedDisableDirectives, we would limit what kind of changes we could publish in a semver-patch release (since fixing a bug that would result in fewer errors could create additional unused disable directives). You can find more information in the original RFC here.

[obweger]

Right, thanks for the context. I wonder if we can make this a consumer choice (we would obviously have to be very explicit about this in the docs); in our case, it would be perfectly fine to fix all unused directives whenever we upgrade eslint or a plugin, especially if the unused directives would be fixable (see #11815).

[platinumazure]

Hi @obweger. Just as a note, if you haven't configured any rules to warn, you could use --max-warnings 0 to ensure that ESLint terminates with a failure status code if unused disable directive warnings are generated in your lint run.

[kaicataldo]

There is precedence for a feature that comes with an explicit “use at your own risk because this feature can’t follow semver and may break your build” warning label in the eslint:all built in config.

[obweger]

@platinumazure 👍thanks for that! I think we can work around it with the --report-unused-disable-directives option, I got this to work also in the IDE. I'm happy for this issue to be closed, however in general I think it would be good to have this available through the regular config!

[NickHeiner]

I would also like the option to have reportUnusedDisableDirectives be an error-level option when passed as config. My context:

1. I'm perfectly happy to fix errors caused by non-semver-major changes if it means that my disable directives were erroneous.
2. I can't enable --max-warnings 0 because my project currently has hundreds of warnings across 11k+ files.
3. I can't use the CLI option --report-unused-disable-directives because of the various programmatic means (including the Jest runner) by which ESLint is run.

[eslint-deprecated]

Unfortunately, it looks like there wasn't enough interest from the team
or community to implement this change. While we wish we'd be able to
accommodate everyone's requests, we do need to prioritize. We've found
that issues failing to reach accepted status after 21 days tend to
never be accepted, and as such, we close those issues.
This doesn't mean the idea isn't interesting or useful, just that it's
not something the team can commit to.

Thanks for contributing to ESLint and we appreciate your understanding.