updated boost on windows

winx64/include/boost/hana/fwd/difference.hpp

@@ -15,50 +15,18 @@ Distributed under the Boost Software License, Version 1.0.
 
 
 BOOST_HANA_NAMESPACE_BEGIN
-    //! Returns the set-theoretic difference of two sets.
-    //! @relates hana::set
-    //!
-    //! Given two sets `xs` and `ys`, `difference(xs, ys)` is a new set
-    //! containing all the elements of `xs` that are _not_ contained in `ys`.
-    //! For any object `x`, the following holds:
-    //! @code
-    //!     x ^in^ difference(xs, ys) if and only if x ^in^ xs && !(x ^in^ ys)
-    //! @endcode
-    //!
-    //!
-    //! @note
-    //! This operation is not commutative, i.e. `difference(xs, ys)` is not
-    //! necessarily the same as `difference(ys, xs)`. Indeed, consider the
-    //! case where `xs` is empty and `ys` isn't. Then, `difference(xs, ys)`
-    //! is empty but `difference(ys, xs)` is equal to `ys`. For the symmetric
-    //! version of this operation, see `symmetric_difference`.
-    //!
-    //!
-    //! @param xs
-    //! A set to remove values from.
-    //!
-    //! @param ys
-    //! The set whose values are removed from `xs`.
-    //!
-    //!
-    //! Example
-    //! -------
-    //! @include example/difference.cpp
-#ifdef BOOST_HANA_DOXYGEN_INVOKED
-    constexpr auto difference = [](auto&& xs, auto&& ys) {
-        return tag-dispatched;
-    };
-#else
+    // Note: This function is documented per datatype/concept only.
+    //! @cond
     template <typename S, typename = void>
     struct difference_impl : difference_impl<S, when<true>> { };
+    //! @endcond
 
     struct difference_t {
         template <typename Xs, typename Ys>
-        constexpr auto operator()(Xs&& xs, Ys&& ys) const;
+        constexpr auto operator()(Xs&&, Ys&&) const;
     };
 
     constexpr difference_t difference{};
-#endif
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_DIFFERENCE_HPP