compiler/testData/diagnostics/tests/sealed/TreeWhen.fir.kt

sealed class Tree {
    object Empty: Tree()
    class Leaf(val x: Int): Tree()
    class Node(val left: Tree, val right: Tree): Tree()

    fun max(): Int {
        when(this) {
            is Empty -> return -1
            is Leaf -> return this.x
            is Node -> return this.left.max()
        }
    }
}