Compiler should throw an error if I use @HostListener in a service

[mgechev]

I'm submitting a ...

[ ] Regression (behavior that used to work and stopped working in a new release)
[ ] Bug report
[ X ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
Current behavior

I'm allowed to put @HostListener in a service, even if it doesn't work

Expected behavior

The compiler should fail (or at least emit a warning?) telling me that the use of @HostListener within a service (or any other place that doesn't have a host) won't work.

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Just a quality-of-life improvement

By @adamdport
Source angular/angular#17847

[rafaelss95]

@mgechev extending to this... the same happens if you implement/use ngOnInit in a service.

[wKoza]

At first, we can focus on decorators like @HostListener, @HostBinding, @Input, @Output, ... But it would be interesting to work on the life cycle in another rule.