Annotations not extending scala.annotation.Annotation

[OlivierBlanvillain]

scalac accepts this, dotty requires A to extend scala.annotation.Annotation:

class A

object O {
  @A def f = 1
}

[nicolasstucki]

Why does scalac accept this?

[DarkDimius]

May be related:
#389

[odersky]

Why does scalac accept this?

I would have answered: So that we can use Java annotations, but I see that these are already treated as subclasses of annotations. So indeed, I don't see why we should follow scalac here.

[Varunram]

Guys, what's the final conclusion here? Do we follow scalac? Thanks!

[odersky]

I think it's better to require that annotations extends Annotation. Unless we see convincing use cases that do not do this. What are Java's rules?

[Varunram]

In Java, As far as I know, we can not extend Annotation types (since Annotation extends annotation.Annotation)

[odersky]

Yes, but I think Java requires annotations to come from an annotation class (i.e. an @interface), no?

[Varunram]

Yes, sir

[jozanek]

Probably resolved.

[smarter]

Yup.