@derive(Eq)
struct Container {
    val: int;
}

// Ensure derived eq uses pointers by trying to use 'c2' after comparison
test "eq_moves" {
    let c1 = Container { val: 10 };
    let c2 = Container { val: 10 };
    
    // This should call Container__eq(&c1, &c2)
    // If it passed by value, c2 would be moved here
    if c1 == c2 {
        // c2 must still be valid
        assert(c2.val == 10, "c2 moved during equality check!");
    } else {
        assert(false, "c1 != c2");
    }
    
    // Explicitly verify c2 is still valid
    c2.val = 20;
    assert(c2.val == 20, "c2 invalid");
    
    println "Smart Derive Eq Works!";
}