Why does this not work?

fun CoroutineScope.launchIO(block: suspend CoroutineScope.() -> Unit): Job {
    return launch(
        context = IO,
        start = CoroutineStart.DEFAULT,
        block = block
    )
}

If I try to use this in place of the regular launch I get the following error:

java.lang.NoSuchMethodError: 'kotlinx.coroutines.Job com.some.misc.ExtensionsKt.launchIO(kotlinx.coroutines.CoroutineScope, kotlin.jvm.functions.Function2)'

I am more curious as to what I'm missing here rather than this being a serious use case

NoSuchMethodError

usually sounds like the runtime classpath is missing something that was there at compile time. How are you compiling and running this code and the code that calls it?

This is part of a ktor project which I'm running using the gradle run task

Is this a multi-module project? Maybe the module containing

launchIO

is declared as

compileOnly

dependency of the module using it?

@cah I'm able to compile and run your code without errors.