Rule Change: Support `language` and `dialects` to `meta`

[lumirlumir]

What rule do you want to change?

Every rule

What change do you want to make?

N/A

How do you think the change should be implemented?

Other

Example code

meta: {
		type: "problem",

		docs: {
			description: "Disallow HTML tags",
		},

		messages: {
			disallowedElement: 'HTML element "{{name}}" is not allowed.',
		},

		schema: [
			{
				type: "object",
				properties: {
					allowed: {
						type: "array",
						items: {
							type: "string",
						},
						uniqueItems: true,
					},
				},
				additionalProperties: false,
			},
		],
	},

What does the rule currently do for this code?

Currently, none of the rules have the language or dialects fields in their meta.

I noticed that all new rules added to ESLint for TypeScript support now include the language and dialects fields:

https://github.com/eslint/eslint/pull/19562/files#diff-d46d32957ba664c4b406c7587c5e047ab7f719ea98a597e0316837d61be4fc48R150-R151

Like we did for JavaScript, I’d like to suggest adding the language and dialects fields to meta as well.

What will the rule do after it's changed?

I think we could add them like this:

meta: {
    // ...
    language: 'markdown',
    dialects: ['commonmark', 'gfm'],
    // ...
}

The language field should be 'markdown', and the dialects can be 'commonmark' and 'gfm'.

Participation

• I am willing to submit a pull request to implement this change.

Additional comments

No response

[nzakas]

We are holding off on doing this for other plugins as we are revisiting this design:
eslint/eslint#19462

[lumirlumir]

I'm copying and pasting the same concern about adding the languages field to the Markdown plugin from eslint/eslint#20716 (comment).

---

After further investigation of the language plugins, I found that adding a languages field could introduce breaking changes to those plugins.

For example, the Markdown plugin includes a rule called no-bare-urls. This rule works only in Markdown GFM mode, because the condition under which it reports an error is satisfied only when a GFM-compliant parser is used.

So, if we add a languages field, it should be languages: ["markdown/gfm"], and "markdown/commonmark" should be omitted, since this error is never reported in CommonMark mode.

The problem is here. Since using this rule in CommonMark mode does not cause any harm, users may still enable it even when they are using CommonMark mode rather than GFM. Also, the current implementation of the rule visits nodes that can be generated in CommonMark mode, so the node listener functions can still run.

In conclusion, if a user is using the no-bare-urls rule in CommonMark mode, introducing languages: ["markdown/gfm"] would require them to change their configuration file.

So, if we want to add this field, I think it needs to be considered for the next major release, including in language plugins.