Hello, I'm having difficulty compiling the following code fragment using the Intel 9.1 C++ compiler. This little program mimics part of our application and the way we make use of the boost::variant class template. The build log follows at the end. The program itself is totally meaningless, but it just demonstrates a problem in either the compiler or in boost. The strange thing is that this program compiles nicely without any problem using the gcc 3.3.1 compiler on Linux. I appreciate any help. TIA Paul #include <map> #include <string> #include <boost/variant.hpp> using namespace std; template <typename IntT=int> class A { public: A() : m_i(0) { } A(const IntT& i) : m_i(i) { } private: IntT m_i; }; template <typename StringT, typename IntT=int> class B { public: B() : m_pi(0) { } B(const string& s, const IntT& i) : m_pi(new IntT(i)) { } ~B() { delete m_pi; } private: StringT m_s; IntT* m_pi; }; typedef A<> a_t; typedef B<string> b_t; typedef boost::variant<a_t, boost::recursive_wrapper<b_t> > Integer; typedef Integer* IntegerPtr; template <typename CharT, typename IntT, typename DoubleT> class numeric_type : public boost::variant<CharT, IntT*, DoubleT> { public: typedef boost::variant<CharT, IntT*, DoubleT> numeric_type_variant; /// Default constructor. numeric_type() : numeric_type_variant() { } numeric_type(const CharT& ch) : numeric_type_variant(ch) { } numeric_type(IntT* pInt) : numeric_type_variant(pInt) { } numeric_type(const DoubleT& d) : numeric_type_variant(d) { } /* template <typename T> /// Converting constructor. numeric_type(T const& t) : numeric_type_variant(t) { } */ // some more code }; int main(int argc, char* argv[]) { char ba; double bc; // set up map with variant integers map<string, Integer> mapInteger; mapInteger.insert(make_pair("a", a_t(0))); mapInteger.insert(make_pair("b", b_t("b", 1))); numeric_type<char, Integer, double> b(ba); numeric_type<char, Integer, double> c(&mapInteger["b"]); numeric_type<char, Integer, double> d(bc); return 0; } ------ Build started: Project: VariantProblemDemo, Configuration: Debug Win32 ------ Compiling... VariantProblemDemo.cpp C:\Mijn Documenten\Backup\Projects\Work\3rdParty\boost\boost\variant\variant.hpp(1273) : error C2668: 'boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::initialize' : ambiguous call to overloaded function with [ BaseIndexPair=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::state1, Iterator=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::iter1 ] C:\Mijn Documenten\Backup\Projects\Work\3rdParty\boost\boost\variant\detail\initializer.hpp(89): could be 'int boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::initialize(void *,boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::param_T)' with [ BaseIndexPair=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::state1, Iterator=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::iter1 ] C:\Mijn Documenten\Backup\Projects\Work\3rdParty\boost\boost\variant\detail\initializer.hpp(89): or 'int boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::initialize(void *,boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::param_T)' with [ BaseIndexPair=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::state0, Iterator=boost::mpl::aux::iter_fold_impl<2,boost::mpl::begin<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::end<boost::variant<a_t,boost::recursive_wrapper<b_t>>::recursive_enabled_types>::type,boost::mpl::pair<boost::detail::variant::initializer_root,boost::mpl::int_<0>>,boost::mpl::lambda<boost::mpl::protect<boost::detail::variant::make_initializer_node>>::type>::iter0 ] while trying to match the argument list '(void *, const int)' C:\Mijn Documenten\Backup\Projects\Work\3rdParty\boost\boost\variant\variant.hpp(1342) : see reference to function template instantiation 'void boost::variant<T0_,T1>::convert_construct<const T>(const T &,int,boost::mpl::false_)' being compiled with [ T0_=a_t, T1=boost::recursive_wrapper<b_t>, T=int ] VariantProblemDemo.cpp(62) : see reference to function template instantiation 'boost::variant<T0_,T1>::variant<int>(const T &)' being compiled with [ T0_=a_t, T1=boost::recursive_wrapper<b_t>, T=int ] VariantProblemDemo - 1 error(s), 0 warning(s) ---------------------- Done ---------------------- Build: 0 succeeded, 1 failed, 0 skipped