Error while using typescript 3.8 export aliases

[TomTomB]

🐞 bug report

Description

Using typescript 3.8 export aliases produces an error while building.
Happens with ivy enabled as well as disabled.

🔬 Minimal Reproduction

1. Clone the error repo https://github.com/TomTomB/named-exports-issue
2. Run npm i
3. Run ng serve
4. Look inside the terminal output

🔥 Exception or Error

ERROR in ./src/app/stuff/index.ts 1:9
Module parse failed: Unexpected token (1:9)
File was processed with these loaders:
 * ./node_modules/@ngtools/webpack/src/index.js
You may need an additional loader to handle the result of these loaders.
> export * as fromFoo from './foo';

🌍 Your Environment

Angular CLI: 9.1.0-next.3
Node: 12.13.0
OS: win32 x64

Angular: 9.1.0-next.4
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package Version

@angular-devkit/architect 0.901.0-next.3
@angular-devkit/build-angular 0.901.0-next.3
@angular-devkit/build-optimizer 0.901.0-next.3
@angular-devkit/build-webpack 0.901.0-next.3
@angular-devkit/core 9.1.0-next.3
@angular-devkit/schematics 9.1.0-next.3
@angular/cli 9.1.0-next.3
@ngtools/webpack 9.1.0-next.3
@schematics/angular 9.1.0-next.3
@schematics/update 0.901.0-next.3
rxjs 6.5.4
typescript 3.8.3
webpack 4.42.0

[JoostK]

In your project, the "module" compiler flag in tsconfig.json is configured as "esnext". This means that the export is preserved as is, however some part of the toolchain is unable to process that syntax. If you change "module" to "es2015" instead it will work.

[JoostK]

Looks like it's Webpack itself that has to support this syntax so that it can work its magic: webpack/webpack#10460

[TomTomB]

Setting the "module" flag to "es2015" only works, if lazy loading is not used.

Dynamic imports are only supported when the '--module' flag is set to 'es2020', 'esnext', 'commonjs', 'amd', 'system', or 'umd'.

12     loadChildren: () => import('./features/foo/foo.module').then((m) => m.FooModule)