| abstract class AbstractAdd { |
| abstract fun add(s: String): Any |
| } |
| |
| abstract class AbstractStringCollection : AbstractAdd(), Collection<String> |
| |
| class StringCollection : AbstractStringCollection() { |
| override fun add(s: String) = s |
| |
| override val size: Int get() = TODO() |
| override fun contains(element: String): Boolean = TODO() |
| override fun containsAll(elements: Collection<String>): Boolean = TODO() |
| override fun isEmpty(): Boolean = TODO() |
| override fun iterator(): Iterator<String> = TODO() |
| } |
| |
| fun test1(a: AbstractAdd) = |
| a.add("O") as String |
| |
| fun test2(a: AbstractStringCollection) = |
| a.add("K") as String |
| |
| fun box() = |
| test1(StringCollection()) + test2(StringCollection()) |
