// Option 3 — `xx <lvalue>` borrows the operand's storage instead of
// heap-copying. The protocol value's `ctx` points directly at the local;
// mutations through the protocol are visible to the original.
//
// The witness is TrackingAllocator: incrementing the parent allocator's
// counter happens through the Allocator protocol value. If `xx tracker`
// heap-copied the Tracker, the parent counter would land in the copy
// and the local would stay at zero. With Option 3 the local sees the
// increments because they ARE the local.
#import "modules/std.sx";
#import "modules/std/mem.sx";

main :: () -> i32 {
    gpa := GPA.init();
    tracker := TrackingAllocator.init(xx gpa);   // value, stack-local

    // xx tracker — operand is an identifier (lvalue), so the protocol
    // borrows tracker's storage. No heap copy. Mutations propagate.
    push Context.{ allocator = xx tracker, data = null } {
        p := context.allocator.alloc_bytes(128);
        context.allocator.dealloc_bytes(p);
    }

    print("alloc_count   = {}\n", tracker.alloc_count);
    print("dealloc_count = {}\n", tracker.dealloc_count);
    return 0;
}