kotlin/compiler/testData/codegen/box/defaultArguments/function/complexInheritance.kt

// See KT-21968

interface A {
    fun f(cause: Int? = null): Boolean
}

open class B : A {
    override fun f(cause: Int?): Boolean = true
}

class D : B(), A

fun box(): String {
    return if (D().f()) "OK" else "fail"
}