defined but not used [-Wunused-function] 使用 __attribute__((unused)) 告诉编译器忽略此告警

在C程序中，如果定义了一个静态函数或变量，而没有去使用，编译时会有一个警告：

'at_wait_send_finish' defined but not used [-Wunused-function]

 

而使用 __attribute__((unused)) 可以告诉编译器忽略此告警：

__attribute__((unused)) static int at_wait_send_finish(struct at_socket *socket, size_t settings_size)
{
    /* get the timeout by the input data size */
    rt_tick_t timeout = rt_tick_from_millisecond(settings_size);
    rt_tick_t last_time = rt_tick_get();
    size_t size = 0, acked = 0, nacked = 0xFFFF;

    while (rt_tick_get() - last_time <= timeout)
    {
        at_get_send_size(socket, &size, &acked, &nacked);
        if (nacked == 0)
        {
            return RT_EOK;
        }
        rt_thread_mdelay(100);
    }

    return -RT_ETIMEOUT;
}