feat(lint/noUnusedImports): add rule

[Conaclos]

Summary

This PR implements noUnusedImports. The rule reports unused imports and provides a safe code fix to remove them.

Once stabilized, noUnusedVariables should be modified to ignore unused imports.

Splitting noUnusedVariables enables to have more control around unused imports and to provide a safe code fix. This is what does eslint-plugin-unused-imports. This allows supporting some user workflows.

The rule is not recommended because noUnusedVariables is not. Moreover this could conflict with other user workflows.

Test Plan

Tests added.

[ematipico]

Thank you for looking after this. Here's a couple of important notes:

• The logic around React isn't complete, it should use the same utilities we used in the JSX rules. It's a solved problem
• The documentation should state that the code action might remove comments, and the criteria behind it

[github-actions]

Parser conformance results on

js/262

Test result	main count	This PR count	Difference
Total	48863	48863	0
Passed	47808	47808	0
Failed	1055	1055	0
Panics	0	0	0
Coverage	97.84%	97.84%	0.00%

jsx/babel

Test result	main count	This PR count	Difference
Total	40	40	0
Passed	37	37	0
Failed	3	3	0
Panics	0	0	0
Coverage	92.50%	92.50%	0.00%

symbols/microsoft

Test result	main count	This PR count	Difference
Total	6212	6212	0
Passed	1767	1767	0
Failed	4445	4445	0
Panics	0	0	0
Coverage	28.44%	28.44%	0.00%

ts/babel

Test result	main count	This PR count	Difference
Total	639	639	0
Passed	571	571	0
Failed	68	68	0
Panics	0	0	0
Coverage	89.36%	89.36%	0.00%

ts/microsoft

Test result	main count	This PR count	Difference
Total	17224	17224	0
Passed	13123	13123	0
Failed	4101	4101	0
Panics	0	0	0
Coverage	76.19%	76.19%	0.00%

[ematipico]

I wonder if we should have an option instead, and users can add "React" if they need. This is more future-proof, and it doesn't discriminate against some libraries. Who knows if in future we will have other "unused imports".

[Conaclos]

Do you think we could just get rid of the React exception? Since when the issue is fixed in babel?

[ematipico]

Do you think we could just get rid of the React exception?

Yes, we can add an option to the rule, an array of strings:

{
	"noUnusedImports": {
		"level": "error",
		"options": {
			"allowedImports": [
				{ "bindings": ["React"], "import": "react" }
			]
		}
	}
}

So users can allow-list anything they want from any import.

Since when the issue is fixed in babel?

One of the recent versions. It's now possible writing React components without the React at the top of the file.

[Conaclos]

Yes, we can add an option to the rule, an array of strings

I mean without providing any options?

Have you other known use-cases for such a config?

[ematipico]

Only react as far as I know.

Uhmmmm, I'm overthinking it. Let's keep the React exception.

[Conaclos]

I think we can drop the React exception. If users report this issue, we can re-introduce the exception. Moreover, the rule is not recommended.

[Conaclos]

I will merge this PR without the exception. If you think we really need this exception, I can open a follow-up PR.

[ipanasenko]

Hi! I'm integrating Biome linter into our project, and enabling this rule removed all React imports, thus breaking our build. Option to ignore React would be nice, thanks!

[jackTabsCode]

An option to ignore whatever we want would be preferable. I'm using Biome in the Roblox ecosystem (with Typescript), and we have to import it for our JSX implementation to work. Of course, it keeps trying to remove this too.