🚀 feature request

Relevant Package

@angular/core

Description

@Injectable decorators support passing an NgModule reference as a value of the providedIn field, for ex:

@Injectable({ providedIn: MyModule })
class MyProvider {}

This makes the provider tree-shakable (as this provider is not referenced directly inside an NgModule def).

Currently, there is no forwardRef support in the providedIn field of the @Injectable decorator, which forces the limitation of defining an NgModule before an Injectable class. In some cases this is very inconvenient, see PR #41126.

Describe the solution you'd like

We should consider adding forwardRef support to the providedIn property values, so the example above may look like this:

@Injectable({ providedIn: forwardRef(() => MyModule) })
class MyProvider {}