[no-unused-vars] false positive when class property has the same name as import

[kmaraz]

• 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

https://github.com/kmaraz/no-unused-vars-issue
I'll show you the issue in the pictures:

This works as the class property thisWorks has different name from the Test.

This does not work, as the class property Test has the same name as Test import.
Hope it helps! :)
Additional Info

Versions

package	version
@typescript-eslint/eslint-plugin	4.14.2
@typescript-eslint/parser	4.14.2
TypeScript	4.1.3
ESLint	7.18.0
node	14.15.0

[bradzacher]

I believe that the bug is here:

typescript-eslint/packages/scope-manager/src/referencer/ClassVisitor.ts

Line 298 in 7695ef3

this.#referencer.currentScope().referenceDualValueType(identifier);

This is adding a reference to the Test value in the current scope.
However the current scope is the function scope - and the function scope has a Test variable defined (the parameter).
This should be referencing the value from the parent scope instead.

[splincode]

I same this issue:
Angular-RU/angular-ru-sdk#361

[bradzacher]

This is a pretty complex problem to solve for all cases.
Name shadowing sucks to deal with.

On the one hand - one can naively fix this by placing the reference in the parent scope.
However this would then cause this case to break:

import { Test } from './Test';

declare function deco(..._param: any): any;

export class Clazz {
  @deco
  method<Test>(Test: Test) {}
}

I've opened an issue with TypeScript to clarify how it's supposed to work.

[vegerot]

I've opened an issue with TypeScript to clarify how it's supposed to work.

@bradzacher link to this issue?

[bradzacher]

microsoft/TypeScript#42679

[vegerot]

🙂 thanks

[Woebin]

There was a response to the TypeScript issue logged by @bradzacher two weeks ago, see microsoft/TypeScript#42679 (comment) - the response states that the described behavior is expected.

Commenting to point this out as I'm seeing the same linting error as described here, using @typescript-eslint/eslint-plugin@6.7.5 - since this issue is still open, I'm guessing it's not considered resolved in a later version of the plugin either?