// Bindingless `while <optional>` must test the optional's has_value flag,
// exactly like `if <optional>` — not fold the `{T,i1}` aggregate truthy.
//
// Regression (issue 0164): a bare optional loop condition emitted `br i1 true`,
// so the loop never observed `null` and either spun forever (present→drained)
// or ran when it should have been skipped (already-null).
#import "modules/std.sx";

main :: () {
    // Present `?i64` drained to null: the body runs each step until the
    // optional becomes null, then the loop stops.
    countdown : ?i64 = 3;
    runs := 0;
    while countdown {
        runs = runs + 1;
        v := countdown!;          // unwrap the present value
        if v <= 1 {
            countdown = null;     // drain → loop must STOP next header eval
        } else {
            countdown = v - 1;
        }
    }
    print("drain runs={}\n", runs);     // 3

    // Already-null `?i64`: the body must NOT run at all.
    empty : ?i64 = null;
    skipped := 0;
    while empty {
        skipped = skipped + 1;
        empty = null;
    }
    print("skip runs={}\n", skipped);   // 0
}