We've been using Kotlin for a good while, but it j...

# announcements

[bendb]

We've been using Kotlin for a good while, but it just now occurred to me to wonder about this bit of type-inference trivia:
An unconstrained generic parameter T is basically equivalent to <T : Any?>. Why then is a value value: T not smart-cast to T2 such that <T2 : Any>?

The motivating example that I wanted (and which failed) was something like:

fun <T> assertIsInstanceOf(value: T, type: KClass<*>) {
  if (value != null) {
    assert(type.java.isAssignableFrom(value.javaClass)) // this fails to compile as 'javaClass' does not exist on `Any?`
  }
}

The workaround was to declare the function fun <T : Any> assertIsInstanceOf(value: T?, type: KClass<*>), which seems to work, but feels unsatisfying. What could I be missing about generics and smart-casting?