InjectionToken for config不能与AoT一起使用

Question

I'm writing an Angular library where I need to pass in a configuration object in the .forRoot() of the module import.

I'm trying to do this (the apparently correct way) with InjectionToken , but getting an AoT compilation error.

Error when compiling with AoT:

error TS4050: Return type of public static method from exported class has or is using name 'InjectionToken' from external module "/path/to/node_modules/@angular/core/src/di/injection_token" but cannot be named.

Any help is appreciated.

module.ts:

import { NgModule } from '@angular/core';
import { CONFIG, Config } from './config';

@NgModule({ ... })
export class SomeModule {
    static forRoot(config?: Config) {
        return {
            ngModule: SomeModule,
            providers: [
                { provide: CONFIG, useValue: config }
            ]
        };
    }
}

config.ts:

import { InjectionToken } from '@angular/core';

export const CONFIG = new InjectionToken<Config>('config');

export interface Config {
    some?: string;
    values?: string;
    here?: string;
}

Desired usage by another application:

import { NgModule } from '@angular/core';
import { SomeModule } from 'some-library';

@NgModule({
    imports: [
        SomeModule.forRoot({
            // <-- config values here
        })
    ]
})

(Angular 5, TypeScript 2.6.2)

Answer 1

Answer by JB Nizet in comments above...

Needed to specify the type returned by the forRoot method, ModuleWithProviders .

import { NgModule } from '@angular/core';
import { CONFIG, Config } from './config';

@NgModule({ ... })
export class SomeModule {
    static forRoot(config?: Config): ModuleWithProviders {
        return {
            ngModule: SomeModule,
            providers: [
                { provide: CONFIG, useValue: config }
            ]
        };
    }
}