#include <cstdio>
void Bad() { puts("BOOO"); }
struct Expr {
  long a[2];
  long (*Op)(long *);
};
int main(int argc, char **argv) {
  struct Expr e;
  // On écrit indirectement sur la variable Op.
  e.a[2 * argc] = (long)&Bad;
  e.Op(e.a);
}