Type augmentation is broken on ESLint >= 9.38.0

[abarani]

Describe the bug

When the includeAugmentation option is set the generated code contains the following declaration:

declare module 'eslint' {
  namespace Linter {
    interface RulesRecord extends RuleOptions {}
  }
}

In ESLint 9.38.0 Linter.RulesRecord is now a type in place of an interface and thus can no longer be extended:
https://github.com/eslint/eslint/blob/8fe511b4c0fb74df3290271b29c672c3fbf3be1f/lib/types/index.d.ts#L1328

If I'm getting it correctly the new proposed way to extend config type going forward is:

declare module '@eslint/core' {
  interface RulesConfig extends RuleOptions {}
}

As a side note Linter.RuleEntry has been changed too in ESLint 9.39.0. Although it still work as the type is essentially the same, it may be worth importing RuleConfig directly from the @eslint/core module.

Reproduction

Generate any .d.ts file with includeAugmentation set

System Info

-

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A, please open a GitHub Discussion instead.
• The provided reproduction is a minimal reproducible of the bug.

Contributions

• I am willing to submit a PR to fix this issue
• I am willing to submit a PR with failing tests (actually just go ahead and do it, thanks!)

[benedictleejh]

Just in case anyone runs across this when trying to fix type augmentation in >=9.38.0, due to eslint/eslint#19843 (comment), simply updating the code to the above won't actually work currently.

The current workaround would be as follows:

import type { RuleConfig, RulesConfig } from '../node_modules/@eslint/core/dist/cjs/types.cjs' // Or wherever @eslint/core is located

declare module '../node_modules/@eslint/core/dist/cjs/types.cjs' {
  interface RulesConfig extends RuleOptions {}
}

And replacing all Linter.RuleEntry with RuleConfig.

Due to things not entirely being settled around this issue at the moment, I'm not even sure eslint-typegen should ship this workaround for >=9.38.0 or just wait for things to be finalised on this front from ESLint

[NULL0B]

Hi @antfu. Thanks for this project, could you bring your attention into this? would be possible to use this with "@vue/eslint-config-typescript"; defineConfigWithVueTs? Thanks