// Phase 29ab P3: Pattern2 LoopBodyLocal seg Freeze (read-only violation)
//
// Goal:
// - break condition uses LoopBodyLocal seg
// - seg is reassigned in the loop body (read-only contract violation)
// - Pattern2 promotion must Freeze (fail-fast)
//
// Expected: JoinIR freeze error (non-zero exit)

static box Main {
    main() {
        local s = "ab "
        local i = 0

        loop(i < s.length()) {
            local seg = s.substring(i, i + 1)

            if seg == " " || seg == "\t" {
                break
            }

            seg = "x"
            i = i + 1
        }

        print(i)
        return i
    }
}