Hi guys, is this some compiler bug? With the code https://hasteb.in/tosejohu.kotlin, the node.left and node.right are not automatically casted as thecorrect types, even though the if statement checks, and we can see from the docs that it technicaly should. https://kotlinlang.org/docs/reference/typecasts.html

var local variables - if the variable is not modified between the check and the usage, is not captured in a lambda that modifies it, and is not a local delegated property;

The segment from the doc you quote is about smartcasting the

var

itself, not its properties. Right below that it says:

var properties - never (because the variable can be modified at any time by other code).

it’s a local var though, and smartcasting works at least at the top level (of those nodes)

Yeah I agree that it's weird, but at least it matches the docs 😒imple_smile:

fun test() {
    var node = createBin()

    if (node is BinaryOp) {
        var left = node.left
        var right = node.right
        if (left is IntLit && right is IntLit) {
            right.token.value // unresolved reference: value
            val right = node.right as IntLit
            right.token.value // no problem
        }
    }
}

this works, and I feel like it shouldn’t if that were the case

i also saw that, but if that is talking about vars in local contexts too, it is contradictory

Hmmm… this works:

if(node is BinaryOp) {
        val l = node.left
        val r = node.right
        if(l is IntLit && r is IntLit) {
            r.token.value 
            l.token.value 
        }        
    }

@Shawn That just compiles for me fine, what is that comment about?

i think he left the comment in the snippet from my example

@streetsofboston Of course if you explicitly create temporary vars you're in the local var case again which indeed works.

@Timothy Wong yeah, my b

Yep, exactly… whether you put

node.left

(and same for

node.right

) in a temporary variable

l

or not should not matter….