1  typedef __builtin_va_list va_list;
       2  
       3  extern void foo (va_list);
       4  
       5  static void
       6  build_message_string (const char *msg, ...)
       7  {
       8    va_list ap;
       9  
      10    __builtin_va_start (ap, msg);
      11    foo (ap);
      12    __builtin_va_end (ap);
      13  }
      14  
      15  void
      16  file_name_as_prefix (f)
      17       const char *f;
      18  {
      19    build_message_string ("%s: ", f);
      20  }
      21