Hello. I encountered a case where "usedAsExpression" property for "when" expression returns false, w...

# k2-adopters

[Roman]

Hello. I encountered a case where "usedAsExpression" property for "when" expression returns false, while I'm expecting it should return true.

fun test(c: Boolean, d: Boolean) {
    val a = if (c) {
        val b = "One"
        if (d) {
            b
        } else {
            "Two"
        }
    } else {
        "Three"
    }
}

Here, "usedAsExpression" for the outer "if" is true, while for the inner "if" is false. Is that correct? Obviously, the inner "if" is used as expression as well as the outer one.

How can I check that condition beside "usedAsExpression" property?

[dmitriy.novozhilov]

FirWhenExpression.usedAsExpression is initialized only based on source structure without any resolution and it might be not precise

[dmitriy.novozhilov]

So you can expect false-negatives from it (but not false-positives)

[Roman]

So, the only option here is to do analysis of this expression on my side? K1 API worked in this case...

[dmitriy.novozhilov]

Yes, it is the only option

[dmitriy.novozhilov]

Note that usedAsExpression is an internal implementation detail without any contracts for outer consumers