Hello, Barend and I have been facing a problem while integrating concept checks into the Geometry Library. In order to simplify the problem, I reduced it to a very simple test case: template <typename T> struct foo {}; template <class X> struct DummyConcept { typedef typename X::something something; }; template<typename T> BOOST_CONCEPT_REQUIRES(((DummyConcept<T>)), (void)) func(T&) { std::cout << "first overload" << std::endl; } template<typename T> void func(foo<T>) { std::cout << "second overload" << std::endl; } int main() { func(foo<int>()); return 0; } This code doesn't compile because the compiler tries to check foo<int> against the DummyConcept, even though it's supposed to select the second overload, which doesn't carry any concept requirement. Removing the check makes it compile and a run displays "second overload". If I put back the check and add a "typedef void something" into foo, it compiles and displays the same thing. So I deduce that, more generally, a compiler compiles the return type of every candidate overload before selecting the right one, and that's why we have this issue with concept checking. So I have 2 questions: - would there be any way to differ the check until after the right overload has been selected, thus doing the check only for that overload? - if no, is there a better workaround than replacing BOOST_CONCEPT_REQUIRES by a simple BOOST_ASSERT inside the function? Thanks in advance. Bruno