// FIR_IDENTICAL
// !DIAGNOSTICS: -UNUSED_PARAMETER

open class Cls

abstract class In<in I>
class SubIn : In<Cls?>()

inline fun <reified T : Cls> materialize(): T? = TODO()

fun <D> transform(transformer: In<D>, data: D): Unit = TODO()

fun test(subIn: SubIn) {
    transform(subIn, materialize()) // D should be inferred to Cls?, not Nothing?
}