有如下一段代码，为何在外部可以访问ev_ncalls而不需要经过_ev和ev_signal两层封装呢？
我自己用gcc也编译不过，我是看到libevent源码里这么写的，在其他地方也看到过，我写了下也编不过去所以来问下
struct event *ev;
int ncall = ev->ev_ncalls;
struct event {
union {
/* used for io events */
struct {
TAILQ_ENTRY(event) ev_io_next;
struct timeval ev_timeout;
} ev_io;
/* used by signal events */
struct {
TAILQ_ENTRY(event) ev_signal_next;
short ev_ncalls;
/* Allows deletes in callback */
short *ev_pncalls;
} ev_signal;
} _ev;
};
struct event
{
union {
/* used for io events */
struct {
TAILQ_ENTRY(event) ev_io_next;
struct timeval ev_timeout;
};
/* used by signal events */
struct {
TAILQ_ENTRY(event) ev_signal_next;
short ev_ncalls;
/* Allows deletes in callback */
short *ev_pncalls;
};
};
};
