Bug: incorrect load children for lazy module when use typings

[splincode]

🐞 Bug report

Command (mark with an x)

- [ ] new
- [x] build
- [ ] serve
- [ ] test
- [ ] e2e
- [ ] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc

Description

When I use typing and add module as argument

app-routing.module.ts

 loadChildren: (): Promise<any> =>
       import('./view/auth/auth.module').then((module: any) => module.AuthModule)

Build failed

WARNING in 
Found 'loadChildren' with a non-string syntax in src/app/app-routing.module.ts but could not transform it.
Make sure it matches the format below:

loadChildren: () => import('IMPORT_STRING').then(M => M.EXPORT_NAME)

Please note that only IMPORT_STRING, M, and EXPORT_NAME can be replaced in this format.

Visit https://v8.angular.io/guide/ivy for more information on using Ivy.

but if we change

 loadChildren: () => import('./view/auth/auth.module').then((m) => m.AuthModule)

it's work, but why? This behavior is not obvious enough, I want to specify types forcibly everywhere, but as a result, the parsing does not work correctly! Problem reproduced with only AOT.

🌍 Your Environment

Angular 8.0.1

[filipesilva]

This breaks because we have to rewrite that import to work with AOT. There isn't code in the rewrite logic to account for all the forced typings yet.

[clydin]

Also of note is that using “any” disables type checking. From an error reporting and code quality perspective it’s actually better to let TypeScript infer the types.

[PranoySarkar]

Looks like similar issue I am facing, for
For
loadChildren:()=>import('./camera/camera.module').then(mod=> mod.CameraModule)
Works perfectly fine, but if I change any lamda to regular function it dosn't generates any chunk file.

So the bellow code doesn't work.

 loadChildren: function () {
            return import('./camera/camera.module').then(function (module) {
                return module.CameraModule;
            });
        }

The error is

ERROR Error: Uncaught (in promise): Error: Runtime compiler is not loaded
Error: Runtime compiler is not loaded
Environment 8.2.2

My concerns ?

1. Is it a bug ?
2. is loadChildren really expecting a function or it is just a spatial token that angular compiler know and parses accordingly ?
3. Is there any change if the behavior will change ?

Thanks for your time.

[smile2014]

ERROR Error: Uncaught (in promise): Error: Runtime compiler is not loaded
Error: Runtime compiler is not loaded
at $v.Mv (main-es2015.f8cb835aabed0f0f97ac.js:1)
at c.string.he.pipe.e [as project] (main-es2015.f8cb835aabed0f0f97ac.js:1)
at c._tryNext (main-es2015.f8cb835aabed0f0f97ac.js:1)
at c._next (main-es2015.f8cb835aabed0f0f97ac.js:1)
at c.next (main-es2015.f8cb835aabed0f0f97ac.js:1)
at e.then.e (main-es2015.f8cb835aabed0f0f97ac.js:1)
at l.invoke (polyfills-es2015.79cfc60b46d0d7fc4d59.js:1)

{ path: 'monitor', loadChildren: () => {
if (environment.fn) {
return import('./pages/export-pdf/export-pdf.module').then(m => m.ExportPdfModule);
} else {
return import('./pages/monitor/monitor.module').then(m => m.MonitorModule);
}
}
},