{ %FAIL } program tw31973; {$mode objfpc}{$H+} uses Classes, SysUtils { you can add units after this }, gutil, gset; type TIntegerSetCompare = specialize TLess; TIntegerSet = specialize TSet; var ISet: TIntegerSet; I: Integer; Iterator: TSet.TIterator; //should be TIntegerSet.TIterator; begin ISet := TIntegerSet.Create(); Iterator := ISet.Find(42); //error2014052306.lpr(20,12) Error: Internal error 2014052306 end.