I'm trying out K2 to a large JVM codebase currentl...

# k2-adopters

[mitch]

I'm trying out K2 to a large JVM codebase currently.. and tests are failing at runtime due to Exception in thread "main" java.util.NoSuchElementException: Array is empty.

This used to work in 1.9, is this a bug? or am I doing something wrong?

tailrec suspend fun <T> doStuff(vararg items: String, fn: suspend () -> T): T = when (items.size) {
  0 -> fn()
  else -> doStuff(*items.drop(1).toTypedArray()) {
    println(items.first()) // this explodes with java.util.NoSuchElementException: Array is empty with K2
    fn()
  }
}

suspend fun main() {
  doStuff("1", "2", "3") { println("yay") } 
}

[mitch]

with K2

Exception in thread "main" java.util.NoSuchElementException: Array is empty.
	at kotlin.collections.ArraysKt___ArraysKt.first(_Arrays.kt:1012)
	at MainKt$doStuff$2.invokeSuspend(Main.kt:172)
	at MainKt$doStuff$2.invoke(Main.kt)
	at MainKt$doStuff$2.invoke(Main.kt)
	at MainKt.doStuff(Main.kt:170)
	at MainKt.main(Main.kt:178)
	at MainKt$main$3.invoke(Main.kt)
	at MainKt$main$3.invoke(Main.kt)
	at kotlin.coroutines.intrinsics.IntrinsicsKt__IntrinsicsJvmKt$createCoroutineUnintercepted$$inlined$createCoroutineFromSuspendFunction$IntrinsicsKt__IntrinsicsJvmKt$1.invokeSuspend(IntrinsicsJvm.kt:270)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlin.coroutines.ContinuationKt.startCoroutine(Continuation.kt:115)
	at kotlin.coroutines.jvm.internal.RunSuspendKt.runSuspend(RunSuspend.kt:19)
	at MainKt.main(Main.kt)

with 1.9

3
2
1
yay

[kirillrakhman]

Please report an issue.

[mitch]

Thanks @kirillrakhman. Reported https://youtrack.jetbrains.com/issue/KT-63973/Possible-regression-in-K2-when-vararg-is-used-within-a-tail-recursive-function