fix(eslint-plugin-react-compiler): add TypeScript type declarations

[everettbu]

Mirror of facebook/react#35856
Original author: sleitor

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Summary

Add a hand-written index.d.ts to provide TypeScript types for eslint-plugin-react-compiler. This fixes the implicit any type error when importing the plugin with checkJs enabled in tsconfig.json.

The declaration file exports the three public symbols: configs, rules, and meta.

Fixes #31334

Changes

• Added index.d.ts with type declarations for the plugin's public API
• Added "types": "index.d.ts" to package.json
• Added index.d.ts to files array so it's included in npm package

[greptile-apps]

Greptile Summary

Adds hand-written TypeScript type declarations (index.d.ts) for eslint-plugin-react-compiler to fix implicit any errors when importing the plugin with checkJs enabled. The package.json is updated to reference the new declaration file.

• The exported types (meta, configs, rules) accurately reflect the runtime shape of the module's public API
• Minor: the severity field in configs.recommended.plugins['react-compiler'].rules is typed as string rather than a narrower string literal union matching the actual ErrorSeverity enum values

Confidence Score: 4/5

• This PR is safe to merge — it only adds a type declaration file and updates package.json metadata with no runtime changes.
• Score of 4 reflects that the type declarations correctly match the runtime exports. The only concern is a minor loss of type precision (string vs string literal union for severity), which is a style improvement rather than a correctness issue.
• Minor attention on compiler/packages/eslint-plugin-react-compiler/index.d.ts for the imprecise severity: string typing.

Important Files Changed

Filename	Overview
compiler/packages/eslint-plugin-react-compiler/index.d.ts	New hand-written TypeScript declaration file. Exports (meta, configs, rules) correctly match the runtime source. Minor: severity typed as string instead of the more precise `'Error'
compiler/packages/eslint-plugin-react-compiler/package.json	Adds "types": "index.d.ts" and includes index.d.ts in the files array. Both changes are correct and necessary for distributing the type declarations.

_{Last reviewed commit: 36045c1}

[greptile-apps]

_{2 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Severity type could be more precise

The runtime type for severity is ErrorSeverity (from babel-plugin-react-compiler), which is an enum with values 'Error' | 'Warning' | 'Hint' | 'Off'. Using string here is technically correct but loses type specificity for consumers. Consider using a string literal union instead:

Suggested change

	rules: Record<string, {rule: Rule.RuleModule; severity: string}>;
	rules: Record<string, {rule: Rule.RuleModule; severity: 'Error' | 'Warning' | 'Hint' | 'Off'}>;

This would give consumers better autocomplete and type safety without needing to import across package boundaries.

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: compiler/packages/eslint-plugin-react-compiler/index.d.ts
Line: 18

Comment:
**Severity type could be more precise**

The runtime type for `severity` is `ErrorSeverity` (from `babel-plugin-react-compiler`), which is an enum with values `'Error' | 'Warning' | 'Hint' | 'Off'`. Using `string` here is technically correct but loses type specificity for consumers. Consider using a string literal union instead:

```suggestion
        rules: Record<string, {rule: Rule.RuleModule; severity: 'Error' | 'Warning' | 'Hint' | 'Off'}>;
```

This would give consumers better autocomplete and type safety without needing to import across package boundaries.

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.