I think following test case is correct. But g++-4.0 produces a diagnostics. We should be able to declare 
a private member function of a class as a friend of another class in order for the member function be 
able to access private members of the befriended class. 

class FriendTestTo;

class FriendTestFrom
{
private:
        void reallySetIt (FriendTestTo* PF);
};

class FriendTestTo
{
private:
  int i;
  friend void FriendTestFrom::reallySetIt (FriendTestTo*);
};

void FriendTestFrom::reallySetIt (FriendTestTo* PF){ PF->i = 1; };
% g++ -c test.cc
test.cc:6: error: 'void FriendTestFrom::reallySetIt(FriendTestTo*)' is private
test.cc:13: error: within this context

Workaround is to declare class FriendTestFrom as friend of class FriendTestTo.