Note 104: At the time, the Delphi 6 compiler was smart enough to acknowledge the error [variant support not found because the Variants unit is not in the uses statement] and add the extra uses statement automatically, issuing a warning. When moving a Delphi 5 project to a much later version, you'll have to do the operation manually.
This blog post is part of my "113 Delphi 2007 Handbook Notes" blogging project, to promote my new Delphi book.