eslint v9 support

[ljharb]

(see also #2478, #2223, #2036, #1834, #1447)

eslint v9 was released on 2024.04.05.

The current plan is, if possible, to release a new semver-minor of both configs, that supports 7 || 8 || 9.

Note that this is different from whether flat config is supported or not by these plugins, and from whether this project will convert to flat config.

The timeframe for eslint v9 support is "not as soon as you would like, but as soon as we can".
Please accept this, and please add no noise to this thread beyond emoji reactions - distractions won't help anyone get the work done any faster.

Please do not file additional issues and do not file pull requests attempting to add support - please, instead, continue to use eslint v8 until such time as our configs support v9.

Peer Dep eslint combined v7, v8, and v9 support released:

• eslint-plugin-import (PR)
  • flat config support (PR)
• eslint-find-rules
• update the base config
• publish the base config, semver-minor
• eslint-plugin-react
  • flat config support
• eslint-plugin-jsx-a11y (PR)
  • flat config support
• eslint-plugin-react-hooks (PR)
  • flat config support
• update the main config
• publish the main config, semver-minor

[controversial]

Updates to the checklist above:

• eslint-plugin-react now has support for eslint 9 and flat config [1]
• eslint-plugin-react-hooks has support for eslint 9 in its canary [2]. They’re waiting for React 19 to ship (which is held up indefinitely by their issues with suspense orchestration) to release stable. Flat config works with the canary release.

eslint-plugin-jsx-a11y still has flat config support but not eslint 9 support; and there’s nothing completed for eslint-plugin-import or eslint-find-rules

[rarenatoe]

Is this PR enabled now? #2826

For the record: eslint-plugin-import now supports flat configs

[ljharb]

technically yes, but until both packages can support it there’s no point in doing it for one.

[hubjongit]

The eslint-plugin-react-hooks PR is merged and available at least in canary release (can be checked off?), and flat config support for it has a PR now waiting to be merged (can be linked). @michaelfaith really putting in the work to help get all these pre-reqs complete.
Is Airbnb support gonna happen soon?