Consider things like -Wextra -Weffc++ -Werror for gcc (from https://sourceforge.net/tracker/?func=detail&aid=3290903&group_id=158151&atid=806686), -Wall, etc. Make sure that, at a minimum, header files build cleanly at reasonably elevated warning levels.

However, users can of course enable and disable their own warnings before including UT++ by using a redirect header, so this may not happen in 1.5.