libstdc++/4168 is not a bug

[Philip Martin]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=4168&database=gcc

This is not a bug, both versions of operator() are required. This is
resolution of issue 109. See

http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-active.html#109

To get your sample code to work change

  struct CmpStrInt : public binary_function<const StrInt, const string, bool>
  {
    bool operator()(const StrInt& l, const string& r) const;
  }

to

  struct CmpStrInt : public binary_function<StrInt, string, bool>
  {
    bool operator()(const StrInt& l, const string& r) const;
  }

Philip