1  void something_f(float);
       2  
       3  int foo(void)
       4  {
       5    union
       6    {
       7      float f;
       8      double d;
       9    } u, *pu = &u;
      10  
      11    u.f = 1.0;
      12    something_f(u.f);
      13  }