feat: add eslint peer dependency

[danielrentz]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request?

This package exports TS type definitions referring to eslint types, thus it should publicly include the @types/eslint package.

What changes did you make? (Give an overview)

In packages/compat/package.json, move "@types/eslint" to "dependencies".

Related Issues

fixes #104
fixes #105

Is there anything you'd like reviewers to focus on?

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: danielrentz / name: Daniel Rentz (16c2b63, 8b732e5, 6d91e6b, 2e49538, cb0f833)

[nzakas]

Switching to draft until we resolve #104

[nzakas]

LGTM. Would like another review before merging.

[nzakas]

@danielrentz can you please sign the CLA?

[danielrentz]

done

[JoshuaKGoldberg]

Now that the eslint package itself publishes its own types (eslint/eslint#18854), @types/eslint is no longer necessary in general. I'd assumed the plan was to turn it into a stub type definition per normal DefinitelyTyped practices. Should this be switched to "eslint", along with the meta lower on?

[nzakas]

I'd assumed the plan was to turn it into a stub type definition per normal DefinitelyTyped practices.

We don't know normal DefiniteTyped practices. 😄 Can you open an issue somewhere for this task explaining what it is?

[JoshuaKGoldberg]

eslint/eslint#18928

[JoshuaKGoldberg]

Great, per eslint/eslint#18928 (comment) I'll mark this as needing to switch from @types/eslint to eslint. Thanks @snitin315!

[danielrentz]

switched to eslint ^9.10.0 (first version with bundled typings)
@nzakas @JoshuaKGoldberg Question: Should the "optional" be removed? (Can this package be used without eslint?)

[nzakas]

I think optional can stay. This package doesn't use eslint at runtime, only at dev time to validate types. @JoshuaKGoldberg?

[JoshuaKGoldberg]

👍

[JoshuaKGoldberg]

Correct place to change, but a different place in code now I believe. Thanks!

[nzakas]

We should update eslint to the latest version. I believe that will fix the CI error.

[nzakas]

LGTM. Would like @JoshuaKGoldberg to verify before merging.

[JoshuaKGoldberg]

🚀

[fasttime]

LGTM, thanks!

[silverwind]

Is there a reason why this peer dependency does not include eslint@8?

[fasttime]

@silverwind ESLint v8 has reached end-of-life. See https://eslint.org/version-support/.

[silverwind]

@silverwind ESLint v8 has reached end-of-life. See https://eslint.org/version-support/.

I know, but @eslint/compat is in active use with eslint@8 like for example in this plugin, and this change is introducing a eslint@9 peerDependency, so the major version should have been bumped.

[silverwind]

Upon further inspection, that plugin uses @eslint/compat to convert v8 rules to v9, and the module is only imported for the v9 config, so the peerDependency warning is essentially a non-issue, and I recommend this module to specify ^8 | ^9 for its peerDependencies so that plugins that support both v8 and v9 can work.

[fasttime]

I know, but @eslint/compat is in active use with eslint@8 like for example in this plugin, and this change is introducing a eslint@9 peerDependency, so the major version should have been bumped.

Technically yes, this should have been a breaking change. But @eslint/compat was never intended to work with ESLint v8.

[silverwind]

Technically yes, this should have been a breaking change. But @eslint/compat was never intended to work with ESLint v8.

Yeah, it's not supposed to and it's not actually loaded with eslintrc configs because those configs do not usually import js modules. Problem is that any plugin or config which dual-publishes v8 and v9 and which has the @eslint/compat dependency will result in the peerDependency warning when installed.

I think it's better to just unrestrict the peer dependency to allow such dual publishes because people are still not fully migrated to v9 or flat config (I'm waiting on eslint-plugin-react-hooks, for example).

[fasttime]

I think it's better to just unrestrict the peer dependency to allow such dual publishes because people are still not fully migrated to v9 or flat config (I'm waiting on eslint-plugin-react-hooks, for example).

@silverwind If you would like to suggest a change it's better to open a new issue because closed issues are not actively triaged.