How does Generic work if generic is Int in Kotlin?

Question

I tried to make abstract class for testing because I found weird problem for using generics

abstract class Test<T> {
    open fun hello(vararg data: T) {
        print("Default function")
    }
}

This very simple abstract class has one opened method with vararg keyword. Problem can be reproduced by making another class which extends Test class.

class Hello : Test<Int>() {
    //Problem 1
    override fun hello(vararg data: Int) {
        super.hello(*data) //Problem 2
        println("Override function")
    }
}

About first problem, Kotlin says method doesn't override anything even though this method surely overrides something. Weirdly, this error happens randomly, so I can't tell exact way to reproduce this bug

This error got removed when I add some codes (like really simple code such as println(), etc), but when you compile, it causes same error again.

About second problem, super.hello(*data) causes problem because this requires Array<out Int>, but found parameter is IntArray. I think Kotlin is considering IntArray and Array<*> as different class, but it shouldn't act like this...

I'm using Kotlin 1.4.10 which seems the latest version according to this site.

I'm posting this to check if these 2 problems are bug or if I did something incorrectly because when I change generic to String, all problems get removed. Are there any mistakes I made in these sample codes above?

Answer 1

Known issue: https://youtrack.jetbrains.com/issue/KT-9495

As a workaround, you can use the boxed java.lang.Integer.

class Hello : Test<Integer>() {
    override fun hello(vararg data: Integer) {
        super.hello(*data)
        println("Override function")
    }
}