MPL pop_back problem

I get some weird error messages which I don't really understand when I tried using mpl::pop_back today. The following example (more or less an exact copy of the one in the documentation): ------------------ start code ----------------- #include #include using namespace boost::mpl; void f() { typedef list::type ListType; typedef pop_back<ListType>::type PoppedList; } ------------------ end code ---------------------- fails on gcc 3.2 (Boost 1.30) with: pop_back.cpp: In instantiation of `boost::mpl::pop_back': pop_back.cpp:9: instantiated from here pop_back.cpp:9: base class ` boost::mpl::pop_back_traitsboost::mpl::aux::list_tag::algorithm ' has incomplete type pop_back.cpp: In function `void f()': pop_back.cpp:9: ISO C++ forbids declaration of `type' with no type pop_back.cpp:9: typedef name may not be class-qualified pop_back.cpp:9: parse error before `;' token I'd appreciate if someone could clear this up for me. Regards, -- Tarjei