Method ~A

code/3/3.4.cpp:16–16

    A(A& a):pointer(new int(*a.pointer)) { std::cout << "拷贝" << pointer << std::endl; }    // 无意义的对象拷贝
    A(A&& a):pointer(a.pointer) { a.pointer = nullptr;std::cout << "移动" << pointer << std::endl; }
    ~A(){ std::cout << "析构" << pointer << std::endl; delete pointer; }
};
// 防止编译器优化
A return_rvalue(bool test) {