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kotlinlang

Hey there; Just a little question: Why is this an unchecked cast?
```
val items = mutableListOf&lt;T&gt;()

override fun &lt;U : T&gt; typedItems(): List&lt;U&gt; {
    return items.mapNotNull { it as? U }
}
```
but this is not?
```
val oldStuff = mutableListOf&lt;List&lt;*&gt;&gt;()
val newStuff = oldStuff.mapNotNull { it as? ArrayList&lt;*&gt; }
```

Because of jvm type erasure at runtime, the cast is unchecked, because it cannot check that the type is U

So the cast will succeed and might lead to a runtime error elsewhere. 

If your function were not virtual, you could use an inline function with a `reified` type parameter.