Class requires Angular annotation even when abstract.

Angular 10.0.0 build yields

NG2007: Class is using Angular features but is not decorated while class is marked as abstract.

export abstract class B {}

@Injectable({...})
export class A extends B {}

CLI should be able to compile, as did earlier versions.

[Christopherjl]

In my opinion Component, Directive and Injectable does not make any sense on an abstract class. Clearly this error is a false positive and adding Directive may be a workaround.

[nartc]

@JoostK Using abstract classes which are meant to be extended only. The following example worked in Angular 9

export abstract class Destroyable implements OnDestroy {
  protected $destroyed = new Subject();

  ngOnDestroy() {
    this.$destroyed.next();
    this.$destroyed.complete();
  }
}

// SomeComponent
@Component({...})
export class SomeComponent extends Destroyable implements OnInit {
   ngOnInit() {
      someObservable.pipe(takeUntil(this.$destroyed)).subscribe(...)
   }
}

I think abstract classes should be excluded from the list of required annotations since it’s never meant (or be able to) to be instantiated anyway.