Re: [Groff] Re: groff 1.19.1 compilation with xlC och AIX

[Bruno Hertz]

On Wed, 2004-05-26 at 15:39, Werner LEMBERG wrote:
> Code like this:
> 
>   void end_diversions();
> 
>   class diversion {
>     friend void do_divert(int append, int boxing);
>     friend void end_diversions();
> 
> produces a warning about declaring `end_diversions' twice.  Is
> somebody on the list who knows the C++ standard well enough to decide
> whether this is a feature of g++ or whether this really conforms to
> ANSI C++?
> 

Hmm. Don't know about your g++ versions, but with my Redhat 9 g++ 3.2.2
this does not produce a warning, which to the best of my knowledge is
the correct behavior.

More specifically, according to Stroustrup TC++PL 3rd Ed. the order is
important since a friend declaration does not introduce a name into the
enclosing scope. I.e. in code

  class diversion {
    friend void do_divert(int append, int boxing);
    friend void end_diversions();
  };
  void end_diversions();

end_diversions does not become a friend to diversion. Not sure however
wether it's actually an error.

This view seems to be confirmed by the standard ISO/IEC 14482:

 3.3.1p6
 [Note: friend declarations refer to functions or classes that are
  members of the nearest enclosing namespace, but they do not introduce
  new names into that namespace (7.3.1.2). ... ]

Your code on the other hand

  void end_diversions();
  class diversion {
    friend void do_divert(int append, int boxing);
    friend void end_diversions();
  };

should be perfectly correct.

Bruno


PS: Sorry Werner for mailing to you directly. Unfortunately 'reply'
doesn't do the right thing on this list, which I sometimes forget.