20000113-1.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

struct x { 
  unsigned x1:1;
  unsigned x2:2;
  unsigned x3:3;
};
   
foobar (int x, int y, int z)
{
  struct x a = {x, y, z};
  struct x b = {x, y, z};
  struct x *c = &b;

  c->x3 += (a.x2 - a.x1) * c->x2;
  if (a.x1 != 1 || c->x3 != 5)
    abort ();
  exit (0);
}

main()
{
  foobar (1, 2, 3);
}