45     std::queue<Emplaceable> q;  in main()  local
48     T& r1 = q.emplace(1, 2.5);  in main()
49     assert(&r1 == &q.back());  in main()
50     T& r2 = q.emplace(2, 3.5);  in main()
51     assert(&r2 == &q.back());  in main()
52     T& r3 = q.emplace(3, 4.5);  in main()
53     assert(&r3 == &q.back());  in main()
54     assert(&r1 == &q.front());  in main()
56     q.emplace(1, 2.5);  in main()
57     q.emplace(2, 3.5);  in main()
58     q.emplace(3, 4.5);  in main()
61     assert(q.size() == 3);  in main()
62     assert(q.front() == Emplaceable(1, 2.5));  in main()
63     assert(q.back() == Emplaceable(3, 4.5));  in main()