Why is tslint flagging properties of strongly typed parameters as any when no-unsafe-any is enabled

Question

Having enabled no-unsafe-any tslint rule in my Angular project I started seeing quite a lot of results. Digging in to them it is flagging properties of parameters injected to constructor as of type any even though they are strongly typed classes. I don't understand why these are being flagged, I'm obviously missing something simple here.

Error message:

Unsafe use of expression of type 'any'.

Example component:

@Component({..)}
export class SampleComponent {
  private localString: string;
  constructor(private injectedService: SampleService) {
    this.localString= this.injectedService.stringProperty;
  }
}

And the sample service:

@Injectable({providedIn: 'root'})
export class SampleService {
  public stringProperty: string;
}

Note: If the background is of any use this follows on from this question: Typescript not enforcing or checking return type

Answer 1

The problem is probably that a lot of angular decorators don't have actual return types, they return any. The tslint rules correctly identifies that we are trying to assign any to a place where a decorator is expected.

One solution is to augment the types of the decorators. I activated the rule in one of my projects and these augmentations make the linter happy, you may need to add others as needed:

import { Type } from '@angular/core/src/type';
declare module '@angular/core/src/metadata/directives' {
    export interface InputDecorator {
        // tslint:disable-next-line:callable-types
        (bindingPropertyName?: string): PropertyDecorator;
    }
}
declare module '@angular/core/src/di/injectable' {

    export interface InjectableDecorator {
        (): ClassDecorator;
        // tslint:disable-next-line:unified-signatures
        (options?: {
            providedIn: Type<any> | 'root' | null;
        } & InjectableProvider): ClassDecorator;
    }
}