typedef event_handler_t (*event_handler_t)(event_t*); // compilation error

event_handler_t state2(event_t* e);
event_handler_t state1(event_t* e) {
	switch(e->type) {
	//...
	case SOME_EVENT:
		return state2;
	//...
	}

}
event_handler_t state2(event_t* e) {
	switch(e->type) {
	//...
	case OTHER_EVENT:
		return state1;
	//...
	}
}

//...
event_handler_t event_handler;
//...
event_handler(&e);
//...

typedef struct event_handler {
	struct event_handler (*func)(event_t *);
} event_handler_t;

event_handler_t state2(event_t* e) {
{
	event_handler_t next_handler = {NULL};
	switch(e->type) {
	//...
	case OTHER_EVENT:
		next_handler.func = state1;
		break;
	//...
	}
	return next_handler;
}