Hey there! I think I found a bug in K2 and/or JVM backend. The following code runs fine on K1 (e.g. ...

# k2-adopters

[Marc Reichelt]

Hey there! I think I found a bug in K2 and/or JVM backend. The following code runs fine on K1 (e.g. using Kotlin 1.9.21), but fails with a ClassCastException when run with 2.0.0-Beta2:

val Number.lightyears get() = Lightyears(this.toDouble())
val UInt.lightyears get() = Lightyears(this.toDouble())

data class Lightyears(val years: Double)

fun main() {
    println(2.lightyears)
    println(2U.lightyears)
}

Kotlin Playground: https://pl.kotl.in/0zkCeRL8P

This fails with:

Exception in thread "main" java.lang.ClassCastException: class kotlin.UInt cannot be cast to class java.lang.Number (kotlin.UInt is in unnamed module of loader 'app'; java.lang.Number is in module java.base of loader 'bootstrap')

Is this issue already known?

[mglukhikh]

I don't remember such an issue, so please report it.

[Marc Reichelt]

Thanks - I created https://youtrack.jetbrains.com/issue/KT-64607/K2-extension-functions-on-UInt-and-Number-lead-to-JVM-ClassCastException 👍