//! returns: 0

/// Count guard evaluations.
fn guard(calls: &mut u32, accepted: bool) -> bool {
    set *calls += 1;
    return accepted;
}

/// Check guarded conditional binding.
fn conditional(value: u32, accepted: bool, calls: &mut u32) -> u32 {
    if let case 1 = value; guard(calls, accepted) {
        return 10;
    } else {
        return 20;
    }
}

/// Check guarded binding with a diverging fallback.
fn binding(value: u32, accepted: bool, calls: &mut u32) -> u32 {
    let case 1 = value if guard(calls, accepted) else { return 20; };
    return 10;
}

/// Check guard failure and pattern failure at loop exit.
fn looping(value: u32, limit: u32, calls: &mut u32) -> u32 {
    let mut steps: u32 = 0;
    while let case 1 = value; guard(calls, steps < limit) {
        set steps += 1;
    }
    return steps;
}

/// Check preallocated success blocks without guards.
fn unguarded(value: u32) -> u32 {
    let case 1 = value else { return 0; };
    let mut current = value;
    let mut result: u32 = 0;
    while let case 1 = current {
        if let case 1 = current {
            set result += 1;
        }
        set current = 0;
    }
    return result;
}

/// Exercise both pattern outcomes and guard outcomes for every binding form.
@default fn main() -> u32 {
    for value in 0..3 {
        assert unguarded(value) == (1 if value == 1 else 0);
        for flag in 0..2 {
            let accepted = flag == 1;
            let expected: u32 = 10 if value == 1 and accepted else 20;
            let mut calls: u32 = 0;
            assert conditional(value, accepted, &mut calls) == expected;
            assert calls == (1 if value == 1 else 0);
            set calls = 0;
            assert binding(value, accepted, &mut calls) == expected;
            assert calls == (1 if value == 1 else 0);
        }
        for limit in 0..4 {
            let mut calls: u32 = 0;
            assert looping(value, limit, &mut calls) == (limit if value == 1 else 0);
            assert calls == (limit + 1 if value == 1 else 0);
        }
    }
    return 0;
}