rxjs-add false positive when type is not specified explicitly

[balassy]

I have the following function in an Angular 4 service class:

public get(url: string): Promise<Response> {
  return this._http.get(url).toPromise();
}

Note, that the get function returns an Observable, but this type name is not appearing in the code explicitly.
The .toPromise() function of Observable is imported in rxjs.imports.ts like this:

import 'rxjs/add/operator/toPromise';

And I have the following rule in tslint.json:

"rxjs-add": {
  "options": [{
      "file": "./src/rxjs.imports.ts"
  }],
  "severity": "error"
}

This triggers the following error when running tslint, which seems to be a false alarm:

ERROR: (rxjs-add) C:/Git/MyProject/src/rxjs.imports.ts[4, 1]: 
Unused patched operator in ./src/rxjs.imports.ts: toPromise

Thank you for creating and maintaining this library, Nicholas!

György

[cartant]

First question: are you using TSLint's no-unused-variable rule? That rule has given me major problems in the past. See #4.

[balassy]

Yes, I am using tslint:all ruleset, which turns on no-unused-variable by default. I've checked now, and turning it off fixes this problem.
Thank you!

[cartant]

Yeah, the no-unused-variable rule misbehaves badly. It's had problems that have been 'fixed' before, but it's still broken in a way that affects other rules. It's a pity, as it's a useful rule. However, it's wasted so much of my time on previous occasions and is difficult to debug, so I just switch if off.

[balassy]

All right, thank you very much!