I believe this is a valid C++ statement:

class rlCommand
{
  public:

    union
    {
      unsigned char     rawData[256];

      struct
      {
        unsigned char   id[2];
        unsigned char   size;

        unsigned char   data[253];
      };
    };

    rlCommand() {}
   ~rlCommand() {}
};
 

but g++ complains about it. command.h:52: anonymous class type not used to declare any objects The same thing compiles just fine under MSVC++ 6. Reading the C++ ANSI standard didn''t tell me much about this. Anybody knows if it''s a legal construct?

I tried your code on four different compilers, and only g++ warns about it. Even g++ believe this is a valid declaration, since it accepts the code (it''s a warning, not an error).

Looks like that message is a somewhat misdirected attempt to warn the programmer about any anonymous struct/class/union types for which no objects are declared. Ignore the warning.