In file included from MyDerived.cpp:2:0:
/usr/include/boost/type_traits/is_virtual_base_of.hpp: In instantiation of ‘boost::detail::is_virtual_base_of_impl<MyBase, MyDerived, mpl_::bool_<true> >::Y’:
/usr/include/boost/type_traits/is_virtual_base_of.hpp:70:5:   instantiated from ‘const bool boost::detail::is_virtual_base_of_impl<MyBase, MyDerived, mpl_::bool_<true> >::value’
/usr/include/boost/type_traits/is_virtual_base_of.hpp:78:4:   instantiated from ‘const bool boost::detail::is_virtual_base_of_impl2<MyBase, MyDerived>::value’
/usr/include/boost/type_traits/is_virtual_base_of.hpp:87:1:   instantiated from ‘boost::is_virtual_base_of<MyBase, MyDerived>’
MyDerived.cpp:9:56:   instantiated from here
/usr/include/boost/type_traits/is_virtual_base_of.hpp:64:8: error: conflicting return type specified for ‘boost::detail::is_virtual_base_of_impl<Base, Derived, mpl_::bool_<true> >::Y::Y() [with Base = MyBase, Derived = MyDerived]’
MyDerived.cpp:5:5: error:   overriding ‘virtual int MyDerived::Y()’