desugared.rs

enum StrangeCountIterator { priv A(int), priv B(int) }

impl Iterator<int> for StrangeCountIterator {
    fn next(&mut self) -> Option<int> {
        match *self {
            A(mut i) => {
                i += 1;
                *self = B(i)
                return Some(i);
            }
            B(mut i) => {
                if i % 2 == 0 {
                     i += 2;
                     *self = A(i);
                     return Some(i);
                } 
                goto_keyword_here A(i);
            }
        }
    }
}

fn strange_count() -> StrangeCountIterator {
    A(0)
}

sm.rs

yield fn strange_count() -> int {
    let mut i = 0;
    loop {
        i += 1;
        yield i;
        if i % 2 == 0 {
            i += 2;
            yield i;
        }
    }
}