Support eslint 9

[garak]

Current output:

npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR! 
npm ERR! While resolving: @symfony/webpack-encore@4.6.1
npm ERR! Found: eslint@9.1.1
npm ERR! node_modules/eslint
npm ERR!   dev eslint@"^9.1.1" from the root project
npm ERR!   peer eslint@"^6.0.0 || ^7.0.0 || >=8.0.0" from @eslint-community/eslint-utils@4.4.0
npm ERR!   node_modules/@eslint-community/eslint-utils
npm ERR!     @eslint-community/eslint-utils@"^4.2.0" from eslint@9.1.1
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peerOptional eslint@"^8.0.0" from @symfony/webpack-encore@4.6.1
npm ERR! node_modules/@symfony/webpack-encore
npm ERR!   dev @symfony/webpack-encore@"^4.6.1" from the root project
npm ERR! 
npm ERR! Conflicting peer dependency: eslint@8.57.0
npm ERR! node_modules/eslint
npm ERR!   peerOptional eslint@"^8.0.0" from @symfony/webpack-encore@4.6.1
npm ERR!   node_modules/@symfony/webpack-encore
npm ERR!     dev @symfony/webpack-encore@"^4.6.1" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

[kumardeepakme]

Yes, eslint 9 & postcss-loader 8

[rugbymauri]

should be fixed in #1258

[garak]

should be fixed in #1258

But I don't see any change related to eslint there. Indeed, the proposed changes in the PR still use eslint 8.

[Kocal]

Hello everyone!

I don't think ESLint 9 will ever be supported. What's more, I'm planning to remove ESLint support from Webpack Encore, and there are several reasons for this:

1. "Linting while building" was really popular years ago, but things have changed. People now prefer to lint their code as a separate task (in their IDE, in a pre-commit git hook, in a dedicated command, in CI, etc.), and I'm one of them. It slows you, either when you have to lint your code to finally build it, or because the ESLint/ESLint plugin slowness added to the building process: you reduce your velocity!
   Also, see How to turn off ESLint? vuejs-templates/webpack#73. :)
2. Supporting ESLint in Webpack Encore has not been without its challenges. It required a lot of work (feat: add ESLint 6 support #732, feat: add support for ESLint 7, drop support ESLint 5 #774, Move from eslint-loader to eslint-webpack-plugin, close #847 #985, Allow eslint-webpack-plugin ^4.0 #1190) and sometimes involved some hacks to get things working (I really want to remove the "sync-rpc" dependency).
3. When you add support for a new major version of ESLint, what do we do about the previous ones? Keeping them, but adding more work to support multiple major versions? Or dropping them, but then we need to tag a new major version for Encore? I don't want ESLint to drive our releases process.
4. There are far more efficient alternatives, like Biomejs, Oxlint, etc., and I don't want to see support for these in Encore. Code linting should not be related to a bundling tool.

I plan to deprecate ESLint support in the next minor version and drop it in the next major version, but I'm open to discussion!

[stof]

@Kocal I totally agree with that decision (personally, I never enabled the ESLint integration in Encore, while I'm using ESLint since longer than I'm using Encore)

[garak]

@Kocal it's fine for me. My only concern is the error I reported above, if to fix it you have to remove eslint support, go for it.

[Kocal]

My only concern is the error I reported above, if to fix it you have to remove eslint support

Yes, after removing the integration, ESLint dependencies will be your concern!
That will be much easier for everyone.

[Kocal]

Closing, as ESLint integration has been removed in #1309 for the next major version of Encore (5).