@angular-devkit/build-angular removes custom library decorators from another libraries on production build

[abadakhshan]

🐞 Bug report

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I define some decorators on one of my libraries and use them a lot on other libraries.
When I build my application with --prod Angular compiler removes using of them in generated code.

This problem occurs with @angular-devkit/build-angular@0.802.0 and I have no problem with @angular-devkit/build-angular@0.801.3

[abadakhshan]

I created a repository for demo

https://github.com/abadakhshan/test-build-angular

I have a decorator on "narik-core" (@NarikInject).
Every @NarikInject used in "test-build-angular" source, works fine but those that used in libraries (for example in "narik-core" and "narik-app-core") do not work at all.

If I change "@angular-devkit/build-angular" to "0.801.3" and "typescript" to "3.4.5" everything is OK.

This happens on ng build --prod and there is no problem on "ng serve"

[alan-agius4]

Similar things have also been reported here: ng-packagr/ng-packagr#1307