Is this a compiler bug or am I missing something? ...

# announcements

[Eric Obermuhlner]

Is this a compiler bug or am I missing something?

abstract class A<T> {
    abstract fun broken(vararg values: T): T
}

// Error: Class 'B' is not abstract and does not implement abstract base class member public abstract fun broken(vararg values: Int): Int defined in A
// Error: 'broken' overrides nothing
class B : A<Int>() {
    override fun broken(vararg values: Int): Int {
        return 5
    }
}

The same code works fine if the subclass is with a "normal" object and not a primitive type.
Actually the IntelliJ IDE also thinks it should work, at least it generates the code for it but the compiler then complains about it.
Tested with kotlin 1.3.31

[Pavlo Liapota]

Looks like a bug.
I guess class A expects method that accepts Array<Int> (or Integer[]) while class B has IntArray (or int[]).

[Eric Obermuhlner]

In the meantime I found a bug entry in: https://youtrack.jetbrains.com/issue/KT-9495

[Eric Obermuhlner]

Based on the bug description I have found a workaround:

abstract class A<T> {
    abstract fun broken(vararg values: T): String
}

class B : A<Int>() {
    override fun broken(values: Array<out Int>): String {
        return broken(*values.toIntArray())
    }

    fun broken(vararg values: Int): String {
        return values.joinToString { it.toString() }
    }
}

Unfortunately it pollutes class B with another visible method broken(values: Array<out Int>).
If the bug ever gets fixed the workaround will lead to a syntax error.

Any better ideas?