fn create_closure() fn () int {
    x := 1234
    c := fn [x] () int {
        println(' >> x = ${x}')
        return x
    }
    return c
}

fn test_closure_data_is_kept_alive() {
    c := create_closure()
    assert c() == 1234
    $if gcboehm ? {
        C.GC_gcollect()
    }
    for _ in 0 .. 1000 {
        unsafe {
            p := malloc(8)
            vmemset(p, 0x33, 8)
        }
    }
    $if gcboehm ? {
        C.GC_gcollect()
    }
    assert c() == 1234
}