编译告警处理：dereferencing type-punned pointer will break strict-aliasing rules

代码片段如下：

long triptime;

long now;

triptime = (now - *((uint32_t *)(icp->icmp_data)));

上述代码在编译时由于打开了-Wall -Os选项，编译器会上报如下告警

dereferencing type-punned pointer will break strict-aliasing rules

baidu无果后，决定自己实践来，于是做如下改动：

char *ptmp = icp->icmp_data;

triptime = (now - *((uint32_t *)(ptmp)));

至此，告警消失。