Angular 8.2 custom decorator bug (related github issue)

When running in prod mode, with a ES2015 target, any custom decorator that is used on an input in a library used by the app will simply be ignored.

This repository contains:

• a library (src folder) that provides a my-test component that used a CustomDecorator decorator on its value input, and displays the value
• a test app (test-app folder) that uses my-test by passing it a value

CustomDecorator simply overrides the input by making sure it always has the value success. It also console.log Calling CustomDecorator when called.

This code should then always display success

<my-test [value]="16"></my-test>

In dev mode, with a ES2015 target, success is displayed, and Calling CustomDecorator is displayed in the console.

In prod mode, with a ES5 target, success is displayed, and Calling CustomDecorator is displayed in the console.

But, in prod mode, with a ES2015 target, 16 is currently displayed, and Calling CustomDecorator is not displayed in the console.

Using ng serve or ng build doesn't seem to matter.

The bug is not present in Angular 8.0.x or 8.1.x.

rebuild the library

npm run build-lib # or npm run watch

reproduce the bug in prod mode (ES2015)

npm start -- --prod

Then open http://localhost:3000

no bug in dev mode (ES2015)

npm start

Then open http://localhost:3000

no bug in prod mode (ES5)

npm run start-es5 -- --prod

Then open http://localhost:3000