[FEAT] Add new rule `no-unused-imports`

[ShayanTheNerd]

In VS Code, it's possible to have unused imports automatically removed when saving the file:
.vscode/setting.json

{
  "editor.codeActionsOnSave": {
    "source.removeUnusedImports": "explicit"
  }
}

I think enforcing this as an autofixable ESLint rule (in a shared config, for example) would be beneficial. I'm using eslint-plugin-unused-imports for now, but I prefer not having to install another dependency just for a single rule.

[SukkaW]

I don't get it. eslint-plugin-unused-imports has no dependency at all, and has an installation size of only 15 KiB (unlike eslint-plugin-import-x, which has an installation size of 2.5 MiB, not mentioning that number has already excluded the huge NAPI-RS introduced binaries). I don't see any reason not to use it.

Also, even if we want to port the autofix implementation made by eslint-plugin-unused-import, we should probably ask its current maintainer @antfu for thoughts.

[JounQin]

eslint-plugin-unused-imports depends on @typescript-eslint/eslint-plugin which replies on typescript under the hood, personally I don't quite understand how is that plugin different with no-unused-vars rule so I never used it previously, and if it must be implemented relying on @typescript-eslint, then I think a seperate plugin is suitable or it should be included in @typescript-eslint/no-unused-vars instead.

[SukkaW]

eslint-plugin-unused-imports depends on @typescript-eslint/eslint-plugin which replies on typescript under the hood

No, it doesn't. eslint-plugin-unused-imports is only trying to find that typescript-eslint rules, and if one doesn't have the typescript-eslint installed, eslint-plugin-unused-imports doesn't care anyway. eslint-plugin-unused-imports still works without TypeScript.

The final straw: @typescript-eslint/eslint-plugin is just an optional peer dependency of
eslint-plugin-unused-imports. eslint-plugin-unused-imports doesn't really care whether it is installed or not.

cc @antfu

[JounQin]

OK, thanks for @SukkaW's inputs, then I think it could be ported personally.

[SukkaW]

I think it could be ported personally.

Yeah, it is possible. But it could also be difficult.

The reason behind eslint-plugin-unused-imports trying to load and build upon ESLint's existing no-unused-vars rules (and also trying to load and build upon typescript-eslint ones) is that they want to re-use existing rules as much as possible.

This approach might not fit eslint-plugin-import-x: Should we also mark typescript-eslint as our optional peer dependencies so we can also build upon their rules? Probably not. But if we don't build upon existing rules, should we port the entire no-unused-vars rule then? Probably also not.

And of course all of these are doable, yet TBH, I don't see other reasons to do so (other than we could, and steal very little portion of their userbase?).

Besides, let's hear from eslint-plugin-unused-imports's maintainers as well.

[ShayanTheNerd]

Besides, let's hear from eslint-plugin-unused-imports's maintainers as well.

@sweepline, considering this discussion, would you like to help port your rule to eslint-plugin-import-x?

[SukkaW]

Besides, let's hear from eslint-plugin-unused-imports's maintainers as well.

@sweepline, considering this discussion, would you like to help port your rule to eslint-plugin-import-x?

Currently, the maintainer of eslint-plugin-unused-imports is @antfu, whom I have already cc'd in this issue.