Hi Luke and polygonists, trying to set up some law based tests for boost::polygon I faced difficulties with the overload resolution of operators under msvc-9. This is the code sniplet where the problems occur: ----------------------------------------------------------- #include <boost/validate/laws/law.hpp> #include <boost/polygon/polygon.hpp> // Here I map a PolygonSet class to geometry_concepts according to // the docs: #include <boost/itl_xt/custom_polygon.hpp> namespace boost{namespace itl { template <typename Type> class PolygonCommutativity : public Law<PolygonCommutativity<Type>, LOKI_TYPELIST_2(Type,Type), LOKI_TYPELIST_2(Type,Type)> { // a o b == b o a . . . bool holds() { using namespace boost::polygon; using namespace boost::polygon::operators; Type value_a = this->template getInputValue<operand_a>(); Type value_b = this->template getInputValue<operand_b>(); Type left = value_a; left += value_b; // Compiler fails to find the appropriate overload // but // this works self_assignment_boolean_op<Type,Type,0>(left, value_b); // and also this works boost::polygon::operators::operator+=<Type,Type>(left, value_b); // and this boost::polygon::operators::operator+=(left, value_b); . . . return equivalence(left, right); } }; ----------------------------------------------------------- moreover, if my custom PolygonSet conainer implements an operator += this operator is *silently* chosen by the compiler, so the wrong addition function is called! Contrary to the traditional understanding of a concept, that defines *requirements* for a parameter class it can use, we have to take care here, that the client class *does not* implement certain operations. I am afraid this is not a good thing. I hope this is fixable, may be the error is on my side but I can't see it yet. Regards Joachim