I'm experimenting with context receivers (with Kot...

# getting-started

[Norbi]

I'm experimenting with context receivers (with Kotlin 1.8.0) and I have run into strange things.

One problem is that this code runs normally and prints 4 to the console:

@Test
fun testBug() {
    runBlocking {
        println(f(2) { this() })
    }
}

suspend fun <T> f(value: Int, block: context(A) Int.() -> T): T = block(A(), value)

class A {
    operator fun Int.invoke() = this * 2
}

But making all functions suspend results in a runtime exception:

@Test
fun testBug() {
    runBlocking {
        println(f(2) { this() })
    }
}

suspend fun <T> f(value: Int, block: suspend context(A) Int.() -> T): T = block(A(), value)

class A {
    suspend operator fun Int.invoke() = this * 2
}

java.lang.ClassCastException: class A cannot be cast to class java.lang.Number

Is this a bug?

(Please ignore what the code actually does, it is just an excerpt to reproduce the issue.)

[ephemient]

looks like it's been reported, https://youtrack.jetbrains.com/issue/KT-53551/suspend-functional-type-with-context-receiver-causes-ClassCastException