A simple testcase to point out the problem

stailq.c (text/plain), 653 bytes, created by Martin Storsjö on 2010-03-04 10:16:13 UTC

#include <stdio.h>
#include <stddef.h>
#include <sys/types.h>
#include <sys/queue.h>

#ifndef	STAILQ_LAST
#define STAILQ_LAST(head, type, field)                                  \
        (STAILQ_EMPTY((head)) ?                                         \
                NULL :                                                  \
                ((struct type *)(void *)                                \
                ((char *)((head)->stqh_last) - offsetof(struct type, field))))
#endif

struct foo {
	int a, b;
	STAILQ_ENTRY(foo) next;
};

int main(int argc, char* argv[]) {
	STAILQ_HEAD(, foo) stailq;
	STAILQ_LAST(&stailq, foo, next);
	return 0;
}