struct point {
      int x;
      int y;
    } i = {34, 89}, j;
    struct rect {
      struct point upper_right;
      struct point lower_left;
    };

    struct rect a, b;

    j.x = 83;
    j.y = 68;

    a = {i, j};
    b = a;

    b.upper_right.x == a.upper_right.x; /* true */
    b.lower_left.y == a.lower_left.y; /* true */
    b.lower_left.x == a.lower_left.y; /* false, but allowed */
    a == b; /* not allowed */