C++11

// <atomic> 
​// 类模板(整体)(1)
template <class T>
T atomic_fetch_or_explicit (volatile atomic<T>* obj,
                             T val, memory_order sync) noexcept;
template <class T>
T atomic_fetch_or_explicit (atomic<T>* obj,
                             T val, memory_order sync) noexcept;
// 重载(2)    
T atomic_fetch_or_explicit (volatile A* obj, T val, memory_order sync) noexcept;
T atomic_fetch_or_explicit (A* obj, T val, memory_order sync) noexcept;

将一个原子对象的值与一个非原子参数做逻辑或(Logical OR)操作,其结果保存到原子对象中,且返回原子对象之前的值。