Is it expected that `kotlin.Result.Failure` throws...

# coroutines

[MiSikora]

Is it expected that kotlin.Result.Failure throws instead of delivering value when continuation is resumed on a different thread?

suspend fun main() {
    val failure = fail()
    println(failure)
}

suspend fun fail() = suspendCoroutine<Result<String>> {
    Executors.newSingleThreadExecutor().execute {
        it.resume(Result.failure(RuntimeException()))
    }
}

Exception in thread "main" java.lang.RuntimeException
	at MainKt$fail$2$1.run(main.kt:12)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

[MiSikora]

Making fail() function inline seems to resolve the issue. Anyone knows why that might be?

[gildor]

It looks as the same issue which we have with Result, it's a bug of Kotlin 1.4.0-1.4.10
I tried 1.4.20 dev builda and it fixed there

Could you also check? It's very nice that you have simple reproducible sample, I noticed this only because some of our tests are failed

So it reproducible when there is double wrapping to Result: Result.success(Result.failure(...)), probably threading is what I missed when tried to reproduce

[MiSikora]

I can’t confirm. 1.3.72 works properly, but 1.4.20-dev-3296-10 still fails

[MiSikora]

I’ll report an issue later if someone doesn’t beat me to it

[gildor]

The latest dev build is https://bintray.com/kotlin/kotlin-dev/kotlin/1.4.20-dev-3898-14

Could you try it?

[MiSikora]

Yeah, it’s fixed there

[MiSikora]

FYI there is an issue https://github.com/Kotlin/kotlinx.coroutines/issues/2218 🙂