Hello Everyone- The following code compiles fine with g++ 4.1.2 but does not compile with 4.4.1, I get an error message saying the prototype does not match any declared in the class. This happens both with Boost 1.40.0 and 1.33.1, on Debian (x86 64-bit). Does anyone know what's up with this, is there some workaround? Thanks very much. #include #include #include template<typename T> struct A { struct B {}; template<typename U> typename boost::enable_if_c< boost::is_base_of::value && !boost::is_same::value> ::type f(U&); }; template<typename T> template<typename U> typename boost::enable_if_c< boost::is_base_of::value && !boost::is_same::value> ::type A<T>::f(U&) {} int main() { } t.cpp:20: error: prototype for 'typename boost::enable_if_c<(boost::is_base_of::value && (! boost::is_same::value)), void>::type A<T>::f(U&)' does not match any in class 'A<T>' t.cpp:12: error: candidate is: template<class T> template<class U> typename boost::enable_if_c<(boost::is_base_of::value && (! boost::is_same::value)), void>::type A::f(U&) -Lewis