I've got this function ```@OptIn(ExperimentalContracts::class) inline fun <T, reified S : T> require...

# getting-started

[y]

I've got this function

@OptIn(ExperimentalContracts::class)
inline fun <T, reified S : T> requireSameSubclass(a: T, b: T) {
    contract {
        returns() implies (a is S && b is S)
    }

    if (a !is S || b !is S) {
        throw IllegalArgumentException("uh oh")
    }
}

and when I attempt to use it like so:

val comparator: Comparator<Bar> = Comparator { a: Foo, b: Foo -> 
    requireSameSubclass<Foo, Bar>(a, b)
    a.functionOfBar().compareTo(b.functionOfBar())
}

a and b appear to smart-cast to Bar on IntelliJ, but then compilation fails, thinking that a and b are Foo. is this a bug?

[Youssef Shoaib [MOD]]

Compiles just fine for me on the playground

[y]

strange. and adding

a as Bar
b as Bar

after the require, makes it compile (and IntelliJ detects it as a useless cast). I guess I gotta go track down the anomaly in my company's build setup.

[Youssef Shoaib [MOD]]

Might be an outdated Kotlin version or something. IntelliJ's Kotlin plugin might not be the same exact version as your compiling Kotlin version

[y]

that was my initial thought, but it appears to be 1.9.20. and we have `data object`s in the code, so it has to be pretty new. (>= 1.8.20, apparently)

[Youssef Shoaib [MOD]]

What is the exact error message you're getting?

[Youssef Shoaib [MOD]]

Also, is the requireSameSubclass function in a different module? I think there's a known bug about contract casts not working well cross-module

[y]

wow, I think that's it. it compiles now.