message: forward declarations to make new compilers happy
diff: @@ -33,6 +33,12 @@ SOFTWARE.
  #include <string>
  #include <utility>
  +
  +/* forward declarations */
  +class alt_string;
  +bool operator<(const char* op1, const alt_string& op2);
  +
  +
  /*
  * This is virtually a string class.
  * It covers std::string under the hood.
  