Hello, I'm running into a problem when using boost::result_of with gcc 3.4.2 and 4.2.1 (with MingW). The following program compiles fine with Visual C++ 8.0, but not with gcc: ------------------------------- #include struct test_function1 { template <typename SignatureT> struct result; template <typename T> struct result { typedef T type; }; template <typename T> T operator () (T t) const { return t; } }; template <typename ArgT> struct test_function2 { template <typename SignatureT> struct result; template <typename T> struct result { typedef T type; }; template <typename T> T operator () (T t) const { return t; } }; int main(int argc, char *argv[]) { typedef boost::result_of< test_function1(int)>::type result_type; typedef boost::result_of< test_function2<float>(int)>::type result_type; return 0; } ------------------------------- The error message I get is for the second typedef using test_function2: E:/Projects/Third Party/boost/boost/utility/result_of.hpp: In instantiation of `boost::detail::result_of_nested_result': E:/Projects/Third Party/boost/boost/utility/result_of.hpp:75: instantiated from `boost::detail::result_of_impl' E:/Projects/Third Party/boost/boost/utility/detail/result_of_iterate.hpp:24: instantiated from `boost::result_of' main.cpp:43: instantiated from here E:/Projects/Third Party/boost/boost/utility/result_of.hpp:68: error: invalid use of undefined type `struct test_function2<float>::result' I get the same error if I simply wrap test_function1 in another template class as nested struct and then use it instead of test_function2. Am I attempting to do something fundamentally wrong here, or is it a bug in gcc? Thanks, Martin