//! returns: 0

/// Sum a slice and check its iteration index.
fn sum(values: &[u32]) -> u32 {
    let mut result: u32 = 0;
    for value, index in values {
        assert value == values[index];
        set result += value;
    }
    return result;
}

/// Compare array and slice lengths through every valid subrange.
@default fn main() -> u32 {
    let data: [u32; 6] = [1, 2, 3, 4, 5, 6];
    let empty: [u32; 0] = [];
    let mut total: u32 = 0;
    for value, index in data {
        assert value == index + 1;
        set total += value;
    }
    assert total == 21;
    for value in empty {
        assert false;
    }
    assert sum(&empty[..]) == 0;
    for start in 0..7 {
        for end in start..7 {
            let mut expected: u32 = 0;
            for index in start..end {
                set expected += index + 1;
            }
            assert sum(&data[start..end]) == expected;
            let all: 'whole = &data[..] in {
                assert sum(&all[start..end]) == expected;
                assert sum(&all[start..]) == 21 - start * (start + 1) / 2;
                assert sum(&all[..end]) == end * (end + 1) / 2;
            }
        }
    }
    return 0;
}