Traits: is this bug in my head or in Kotlin? Please help

1

Yesterday I was asked this question on stackoverflow but no one answered. The question is:

Why this code: 

open class Base {
    open fun sayHello(){
        println("Hello, I'm base")
    }
}

trait Trait: Base {

  override fun sayHello() {

  println(“Hello, I’m trait”)

  }

}


class Derived(): Base(), Trait


fun main(args: Array<String>) {

  Derived().sayHello()

}

prints

Hello, I'm base

Moreover, if I override "fun sayHello" in "Derived" by hand: 

class Derived(): Base(), Trait {
    override fun sayHello() {
        super<Trait>.sayHello()
    }
}

it again prints 

Hello, I'm base

What is wrong?

Of course I’m excepting that ouput is:

Hello, I’m trait

In both cases

Kotlin Compiler version 0.5.295

2

Even worse

``

open class Base {

  open fun sayHello(){

  println(“Hello, I’m base”)

  }

}


trait Trait: Base {

  override fun sayHello() {

  println(“Hello, I’m trait”)

  }

  

  fun sayHello2(){

  sayHello()

  }

}


class Derived(): Base(), Trait


fun main(args: Array<String>) {

  Derived().sayHello2()

}

generates Hello, I’m base

3

So, it is bug or not (in Kotlin)?

4

It looks like a bug to me unless I misunderstood how Trait works.

5

I'm created bug report http://youtrack.jetbrains.com/issue/KT-3429

6

Yes, it is a bug, please report to the tracker. Thanks

7

Thank you