I have an Angular CLI workspace containing two library projects, foo and bar. When I build the second of the two libraries, foo, the build fails with the following error:

error TS6059: File '/code/projects/bar/src/lib/types.ts' is not under 'rootDir' '/code/projects/foo/src'. 'rootDir' is expected tocontain all source files.

Error: error TS6059: File '/code/projects/bar/src/lib/types.ts' is not under 'rootDir' '/code/projects/foo/src'. 'rootDir' is expected to contain all source files.

    at Object.<anonymous> (/code/node_modules/ng-packagr/lib/ngc/compile-source-files.js:53:68)
    at Generator.next (<anonymous>)
    at /code/node_modules/ng-packagr/lib/ngc/compile-source-files.js:7:71
    at new Promise (<anonymous>)
    at __awaiter (/code/node_modules/ng-packagr/lib/ngc/compile-source-files.js:3:12)
    at Object.compileSourceFiles (/code/node_modules/ng-packagr/lib/ngc/compile-source-files.js:19:12)
    at Object.<anonymous> (/code/node_modules/ng-packagr/lib/ng-v5/entry-point/ts/compile-ngc.transform.js:26:32)
    at Generator.next (<anonymous>)
    at /code/node_modules/ng-packagr/lib/ng-v5/entry-point/ts/compile-ngc.transform.js:7:71
    at new Promise (<anonymous>)

I have reproduced the error in a sandbox repo on GitHub here. I have simplified the code to as much as I can while still experiencing the error. You can reproduce the error by executing npm run build on the rootDir-expect-all-source-files-error branch. What is the cause of the error? May this be a bug with ng-packagr or ngc or tsc? Or is it simply a configuration issue?

Observations

Below are code changes with which I can make the build pass, but I would like to know what is causing the error with the code as is.

bar.component.ts

Build fails

export class BarComponent {

  list = this.barService.list();

  constructor(private barService: BarService) {}
}

Build passes

Initialize list property in constructor instead of inline

export class BarComponent {

  list;

  constructor(private barService: BarService) {
    this.list = this.barService.list();
  }
}

bar.service.ts

Build fails

import { Injectable } from '@angular/core';
import { List, Item } from './types';

@Injectable({
  providedIn: 'root'
})
export class BarService {

  private _list: List = [];

  constructor() { }

  add(item: Item): void {
    this._list.push(item);
  }

  list(): List {
    return this._list;
  }
}

Build passes

Remove the data types

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

@Injectable({
  providedIn: 'root'
})
export class BarService {

  private _list: any[] = [];

  constructor() { }

  add(item: any): void {
    this._list.push(item);
  }

  list(): any {
    return this._list;
  }
}

This looks like the problem that is occurring due to the import types which was introduced in TypeScript 2.9. When emitted these are not being rewired properly see line 3.

dist/bar/lib/bar.component.d.ts(5,11):

export declare class BarComponent implements OnInit {
    private barService;
    list: import("projects/bar/src/lib/types").Item[]; 
    constructor(barService: BarService);
    ngOnInit(): void;
}

In the above emitted dts, list: import("projects/bar/src/lib/types").Item[]; should be something like import("./types").Item[]; instead.

A workaround for this can be that from your code instead infering the type, you explicitly set it.

in bar.component.ts change the below;

list = this.barService.list();

to:

list: Item[] = this.barService.list();

This will remove the type import and the consuming library will build.

I also checked a bit with future versions of TypeScript, it is still an issue in TypeScript 3.0.1, but it looks like it has been addressed in dev version of TypeScript 3.1.0, ie 3.1.0-dev.20180813