class ClassInt
class ClassLong

class Builder<T>

fun Builder<in ClassInt>.add(value: Int): Unit = TODO()
fun Builder<in ClassLong>.add(value: Long): Unit = TODO()

fun Builder<Any>.test() {
    add(5)
//  ^^^ Overload resolution ambiguity. All these functions match:
//      - public fun Builder<in ClassInt>.add(value: Int): Unit
//      - public fun Builder<in ClassLong>.add(value: Long): Unit
}