Why can't I get the class of a generic parameter?

Question

I have a function which takes one argument of a generic type and I want to access the class of it:

fun <T> test(t: T) {     t::class } 

This fails with "expression in class literal has nullable type". That's ok, I understand it (I could use Any? as my T and null as the value).
But if I change it to guaranty that t is not-null it still fails with the same error message:

fun <T> test(t: T) {     t!!::class } 

In which case can t!!::class still cause trouble?
Is there a way to get the class without using Any (or casting to Any)?

Answer 1

Change your type to indicate it is not-nullable and it should work. You can do this by indicating that T needs to extend Any (rather than Any?).

fun <T : Any> test(t: T) {     t::class }