#include <boost/utility/result_of.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/mpl/assert.hpp>

struct foo {
  template<typename T>
  struct result;
};

template<>
struct foo::result<foo(int)> {
  typedef void type;
};

namespace bst = boost;

BOOST_MPL_ASSERT((bst::is_same<void, bst::result_of<foo(int)>::type>));

int main() {}