I'm using a special version of CodeWarrior for an embedded system, but I suspect that other versions of the software will show the problem. The problem is, basically, the compiler hates polygon_traits<T>. Here's an example from polygon_90_set_traits.hpp: template <typename T> struct traits_by_concept<T, polygon_90_concept> { typedef polygon_traits<T> type; }; It chokes on the typedef, saying "Ambiguous use of partial specialization". This is the complete text of the error message; it provides no other information. Most of the surrounding definitions are very similar, but only the ones that use polygon_traits<T> -- instead of, say, rectangle_traits<T> -- raise errors. Here's another example from polygon_traits.hpp: template <typename T> struct view_of<rectangle_concept, T> { typedef typename polygon_traits<T>::coordinate_type coordinate_type; [snip] }; It chokes on the typedef and any code that tries to use the typedef. The same problem happens with all the other view_of functions and a couple of others, but all the problems seem to deal with the use of polygon_traits<T> in a template. Unfortunately, I know very little about partial specialization, traits classes, or any advanced features of generic programming in C++. My understanding of templates is limited to stuff like making basic containers, generalized sorting functions, etc. -- the easy stuff. So I find the definition of polygon_traits too complicated and am unable to fully comprehend the essence of the problem, let alone how to fix or work around it. Since I need to get this to work, if a proper solution is not obvious, I'm willing to accept any kind of clumsy hack, including disabling parts of the library that I might not need. (I use very little of the Polygon library, but I have a hard time finding an alternative to the part I do use -- namely, finding the union of polygons while allowing for holes. Alternative suggestions in that area are welcome, but I can't use GPLed code, or code that I would need to pay a license for to use commercially.) Any ideas? - Kef