About the Vec (v)->data[(v)->length++] = (val)

[a631069724]

#define vec_push(v, val)
( vec_expand(vec_unpack(v)),
(v)->data[(v)->length++] = (val) )
void dyad_addListener(

dyad_Stream *stream, int event, dyad_Callback callback, void *udata
) {
Listener listener;
listener.event = event;
listener.callback = callback;
listener.udata = udata;
vec_push(&stream->listeners, listener);
}
the listener will be free
how can (v)->data[(v)->length++] = (val) for c