[no-unused-vars] implement destructuredArrayIgnorePattern from eslint 8.11

[neryams]

eslint added a super useful option to the no-unused-vars rule in version 8.11.0, destructuredArrayIgnorePattern.

https://eslint.org/docs/rules/no-unused-vars#destructuredarrayignorepattern

Trying to use this option with typescript-eslint causes eslint to fail because the option is not found.

Here is the PR on the eslint repository related to this feature: eslint/eslint#15649 (there's already discussion on that page about the option not working with this package)

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

use the rule

{
  "rules": {
    "@typescript-eslint/no-unused-vars": ["error", { "destructuredArrayIgnorePattern": "^_" }]
  }
}

with @typescript-eslint/eslint-plugin active. eslint will fail.

Expected Result

eslint should be able to use the destructuredArrayIgnorePattern with @typescript-eslint/eslint-plugin active

Actual Result

eslint fails with the error:

Oops! Something went wrong! :(

ESLint: 8.11.0

Error: Client\.eslintrc.json:
        Configuration for rule "@typescript-eslint/no-unused-vars" is invalid:
        Value {"destructuredArrayIgnorePattern":"^_"} should be equal to one of the allowed values.
        Value {"destructuredArrayIgnorePattern":"^_"} should NOT have additional properties.
        Value {"destructuredArrayIgnorePattern":"^_"} should match exactly one schema in oneOf.

    at ConfigValidator.validateRuleOptions (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2027:23)
    at C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2082:18
    at Array.forEach (<anonymous>)
    at ConfigValidator.validateRules (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2079:34)
    at ConfigValidator.validateConfigArray (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:2205:18)
    at CascadingConfigArrayFactory._finalizeConfigArray (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3947:23)
    at CascadingConfigArrayFactory.getConfigArrayForFile (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\@eslint\eslintrc\dist\eslintrc.cjs:3753:21)
    at FileEnumerator._iterateFilesRecursive (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\eslint\lib\cli-engine\file-enumerator.js:446:49)
    at _iterateFilesRecursive.next (<anonymous>)
    at FileEnumerator.iterateFiles (C:\Repos\kbmax3\KBMax3\KBMax.Fabric.Web\node_modules\eslint\lib\cli-engine\file-enumerator.js:297:49)

Versions

package	version
@typescript-eslint/eslint-plugin	5.15.0
@typescript-eslint/parser	5.15.0
TypeScript	4.0.3
ESLint	8.11.0
node	16.13.0

[boris-petrov]

I never understood what is the benefit of using this rule with TypeScript - doesn't the compiler already do that? Are there cases where the rule does a better job than it?

[bradzacher]

Two quick reasons

• Options. You can configure the rule. You can't configure the TS check.
• Build. The TS error will block the build with noEmitOnError. An eslint rule will not.

[boris-petrov]

I see. Thanks for the answer!