The following code gives me a warning: void trigger (::std ::vector < int > const &v) { ::boost ::size (v) == v. size (); } and the warning is "signed and unsigned in comparison". I understand that (size == end - begin) and that the latter expression is a difference; however, isn't the difference guaranteed to be positive? Also note that no range function ever uses range_size ::type. I suggest that ::boost ::size should return range_size ::type. Chris