#include <setjmp.h>
#include <stdio.h>
#include <time.h>

jmp_buf j;

void do_jump(void) {
  // We can't let the compiler know this will always happen or it might make
  // optimizations that break our test.
  if (clock())
    longjmp(j, 1); // non-local goto
}

int main(void) {
  if (setjmp(j) == 0)
    do_jump();
  else
    return 0; // destination of longjmp

  return 1;
}