[request] compatibility with eslint 9.x

[pyksid]

Agreement

• This is not a duplicate of an existing issue
• I have read the guidelines for Contributing to Roots Projects
• This is not a personal support request that should be posted on the Roots Discourse community

Describe the issue

After upgrading from ESLint 8.x to 9.x, when running bud build, an error occurred and prevented to build assets.

Expected Behavior

bud.js builds assets.

Actual Behavior

$ yarn build

╭ bud [9039cc93a0cfeb1e]                                                                                                                                     ./public
│
│ │ [eslint] Invalid Options:
│ │ - Unknown options: extensions, resolvePluginsRelativeTo, useEslintrc
│ │ - 'extensions' has been removed.
│ │ - 'resolvePluginsRelativeTo' has been removed.
│
╰ 1 error

Steps To Reproduce

yarn build

version

6.23.1

Logs

No response

Configuration

No response

Relevant .budfiles

No response

[kellymears]

I'm removing the bug label because we can only support what we've committed to support, and Eslint 9 is a major upgrade we have not undertaken yet. You can check out the upgrade guide if you're interested.

We won't be able to upgrade @roots/* configs until our next major version because it's such a huge change. It also requires node@18, while we're still trying to support node@16 until bud@7.

eslint-webpack-plugin added support for eslint@9.x.x in v4.2.0 but I notice that if you follow the eslint docs and export an Array from eslint.config.js it will fail (I'm guessing eslint-webpack-plugin tries to parse it as a plain object rather than an array of plain objects, although I didn't look at the source).

Nevertheless, updating it seems like a good idea #2620. I'm just saying that I think it's likely eslint-webpack-plugin will see further changes in support of eslint v9 in the future. We're beholden to any of those changes.

In that same PR there is also a new examples/eslint-9.0.0 project which works using v9.