Is this example, contained in the boost.Proto manual supposed to compile? #include<complex> #include <boost/proto/core.hpp> #include <boost/proto/context.hpp> #include <boost/proto/debug.hpp> #include<boost/proto/extends.hpp> template<class T, class Dummy = boost::proto::is_proto_expr> struct my_complex { BOOST_PROTO_EXTENDS( typename boost::proto::terminal<std::complex<T> >::type , my_complex<T> , boost::proto::default_domain ) }; int main() { my_complex<int> c0, c1; c0 + c1; // OK, operator+ found now! } I get this error (with gcc 4.3 and gcc 4.4): proto_complex.cpp:10: error: expected nested-name-specifier before ‘typename’ proto_complex.cpp:10: error: two or more data types in declaration of ‘proto_base_expr’ proto_complex.cpp:10: error: ‘proto_base_expr’ has not been declared proto_complex.cpp:10: error: ‘proto_base_expr’ has not been declared The strangest thing is that when I replace the macro by its explicit code the code seems to compile. Thank you, Alfredo