1  union u {
       2    unsigned char a;
       3    double b;
       4  };
       5  
       6  int a;
       7  
       8  union u foo (void)
       9  {
      10    union u b;
      11  
      12    if (a)
      13      b.a = 1;
      14    else
      15      b.a = 0;
      16    return b;
      17  }