Is it a bug? On this code

memScoped {
        if (...) {
            value?.let { callVoidFunction1() }
        } else if (..) {
            callVoidFunction1()
        }
    }

I have error on IDEA:

'if' must have both main and 'else' branches if used as an expression

I can fix it by add

} else {

at end but it looks like ugly.

I've seen that sort of thing before in other situations, and it always confuses me. I don't know if it's a bug in IDEA, or some weird quirk in how Kotlin parses that

if/then

statement. Either way, it's definitely non-intuitive. One suggestion: instead of an empty

else

statement, you could do this:

memScoped {
        if (...) {
            value?.let { callVoidFunction1() }
        } else {
          if (..) {
            callVoidFunction1()
          }
        }
    }

Still a little clumsy, but not quite as ugly as having an empty

else

hanging around.

or you could put anything after the

if

, so that it's not being used like a value

memScoped {
    if (...) { ... }
    Unit
}

It's not a bug, it happens because

memScoped

has a return value and lamdas that return values automatically treat the last expression as a return, so the

if

is being treated as an expression (like

val foo = if ...

). As @ephemient mentioned, you could add anything after to be treated as the return instead, or put the conditional in a

run

block, or anything else that makes it clear that the if is not an expression to be returned.

You can

memScoped<Unit> {