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diff --git a/boost/spirit/home/x3/support/traits/make_attribute.hpp b/boost/spirit/home/x3/support/traits/make_attribute.hpp
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+++ b/boost/spirit/home/x3/support/traits/make_attribute.hpp
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+/*=============================================================================
+    Copyright (c) 2001-2014 Joel de Guzman
+    Copyright (c) 2001-2012 Hartmut Kaiser
+    http://spirit.sourceforge.net/
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#if !defined(BOOST_SPIRIT_X3_MAKE_ATTRIBUTE_JAN_8_2012_0721PM)
+#define BOOST_SPIRIT_X3_MAKE_ATTRIBUTE_JAN_8_2012_0721PM
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/spirit/home/x3/support/unused.hpp>
+
+namespace boost { namespace spirit { namespace x3 { namespace traits
+{
+    template <typename Attribute>
+    struct make_attribute_base
+    {
+        static Attribute call(unused_type)
+        {
+             // synthesize the attribute/parameter
+            return Attribute();
+        }
+
+        template <typename T>
+        static T& call(T& value)
+        {
+            return value; // just pass the one provided
+        }
+    };
+
+    template <typename Attribute, typename ActualAttribute>
+    struct make_attribute : make_attribute_base<Attribute>
+    {
+        typedef ActualAttribute& type;
+        typedef ActualAttribute value_type;
+    };
+
+    template <typename Attribute>
+    struct make_attribute<Attribute, unused_type>
+        : make_attribute_base<Attribute>
+    {
+        typedef typename remove_const<Attribute>::type attribute_type;
+        typedef attribute_type type;
+        typedef attribute_type value_type;
+    };
+
+    template <typename Attribute, typename ActualAttribute>
+    struct make_attribute<Attribute&, ActualAttribute>
+      : make_attribute<Attribute, ActualAttribute> {};
+
+    template <typename Attribute, typename ActualAttribute>
+    struct make_attribute<Attribute const&, ActualAttribute>
+      : make_attribute<Attribute const, ActualAttribute> {};
+
+    template <typename ActualAttribute>
+    struct make_attribute<unused_type, ActualAttribute>
+    {
+        typedef unused_type type;
+        typedef unused_type value_type;
+        static unused_type call(unused_type)
+        {
+            return unused;
+        }
+    };
+    
+    template <>
+    struct make_attribute<unused_type, unused_type>
+    {
+        typedef unused_type type;
+        typedef unused_type value_type;
+        static unused_type call(unused_type)
+        {
+            return unused;
+        }
+    };
+}}}}
+
+#endif