I noticed that this compiles: ```fun foo(): Int { ...

# compiler

[Rohen Giralt]

I noticed that this compiles:

fun foo(): Int {
    while (true) {
        return 0
    }
}

But this doesn't (it gives "Return type mismatch: expected 'Int', actual 'Unit"):

fun foo(): Int = run {
    while (true) {
        return@run 0
    }
}

This compiles, but warns that the second 0 is unreachable code.

fun foo(): Int = run {
    while (true) {
        return@run 0
    }
    0
}

Does anyone know why? And is there any way to write code like the second example without any warnings? (In my case, this is occurring with coroutineScope, so I can't just remove it like one could with run).

[Youssef Shoaib [MOD]]

Likely a compiler bug. Regardless, you can fix it as such:

fun foo(): Int = run {
    forever {
        return@run 0
    }
}

inline fun forever(block: () -> Unit): Nothing {
    while (true) block()
}

[Rohen Giralt]

Thanks! That's a good solution.

[hfhbd]

https://youtrack.jetbrains.com/issue/KT-63090/False-positive-UNREACHABLECODE-with-qualified-return-inside-infinite-loop

[hfhbd]

Also https://youtrack.jetbrains.com/issue/KT-25023/Infinite-loops-in-lambdas-containing-returnlabel-dont-coerce-to-any-type

[Youssef Shoaib [MOD]]

I knew it sounded familiar! Turns out, I commented on the latter issue with an identical workaround!