Question: This is probably because I'm using an ol...

# getting-started

[Kelvin Chung]

Question: This is probably because I'm using an older version of Kotlin, but with the version of Kotlin that I am using, it seems like I have to explicitly override whenever I have a situation like this:

interface Base<T> {
  fun doSomething(): T
}
interface IntBase : Base<Int> {
  override fun doSomething() = 0
}

interface MyInterface : Base<Int>, IntBase {
  override fun doSomething() = super.doSomething()
}

It seems like I am required to have the line in MyInterface, despite only inheriting a default implementation from only one place. Is this normal, or is it because I'm using an older version of Kotlin?

[Joffrey]

Which version of Kotlin are you using? This compiles fine without the override even in Kotlin 1.2:
https://pl.kotl.in/60k6K3tYk

[Joffrey]

Did you try this exact code? Maybe your simplification made the example too different from your real code

[Gleb Minaev]

I had similar issue with a bit different code on Kotlin 2.0.0-Beta4: https://youtrack.jetbrains.com/issue/KT-65793/K2-False-positive-MANYIMPLMEMBERNOTIMPLEMENTED-with-interface-hierarchy

[Kelvin Chung]

Try

interface Base<T> {
  val value: T
}
interface IntBase : Base<Int> {
  override val value get() = 0
}

interface MyIntBase : Base<Int>, IntBase

The compiler is saying that I have to explicitly override value in MyIntBase , despite there being only one super-interface where a default implementation is provided.

[Joffrey]

That's exactly what I did in the playground link above and it works in Kotlin 1.2.71 and 2.2.20-Beta1

[Kelvin Chung]

Odd. My project is configured to build with language version 1.9 against a 1.8 API. It is a KMP project, but the code is in commonMain, so it probably shouldn't matter since the only platform-specific code is JVM at the moment.