lvalue-macro.c

/* see <http://stackoverflow.com/questions/1694164/is-errno-thread-safe> */
#include <stdio.h>
#include <stdlib.h>

#define mem (*set_it())

int memory;

int* set_it() {
	return &memory;
}

int main() {
	mem = 2;
	printf("mem: %d\n", mem);
	mem = 4;
	printf("mem: %d\n", mem);
	return EXIT_SUCCESS;
}