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diff --git a/boost/spirit/home/x3/support/traits/has_attribute.hpp b/boost/spirit/home/x3/support/traits/has_attribute.hpp
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+++ b/boost/spirit/home/x3/support/traits/has_attribute.hpp
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+/*=============================================================================
+    Copyright (c) 2001-2014 Joel de Guzman
+    Copyright (c) 2013 Agustin Berge
+    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_HAS_ATTRIBUTE_JUN_6_2012_1714PM)
+#define BOOST_SPIRIT_X3_HAS_ATTRIBUTE_JUN_6_2012_1714PM
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
+#include <boost/spirit/home/x3/support/utility/sfinae.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/not.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/utility/enable_if.hpp>
+
+namespace boost { namespace spirit { namespace x3
+{
+   struct unused_type;
+}}}
+
+namespace boost { namespace spirit { namespace x3 { namespace traits
+{
+    ///////////////////////////////////////////////////////////////////////////
+    // Whether a component has an attribute. By default, this compares the 
+    // component attribute against unused_type. If the component provides a
+    // nested constant expression has_attribute as a hint, that value is used
+    // instead. Components may specialize this.
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Component, typename Context, typename Enable = void>
+    struct has_attribute;
+    
+    namespace detail
+    {
+        template <typename Component, typename Context, typename Enable = void>
+        struct default_has_attribute
+          : mpl::not_<is_same<unused_type,
+                typename attribute_of<Component, Context>::type>> {};
+
+        template <typename Component, typename Context>
+        struct default_has_attribute<Component, Context,
+            typename disable_if_substitution_failure<
+                mpl::bool_<Component::has_attribute>>::type>
+          : mpl::bool_<Component::has_attribute> {};
+    
+        template <typename Component, typename Context>
+        struct default_has_attribute<Component, Context,
+            typename enable_if_c<Component::is_pass_through_unary>::type>
+          : has_attribute<typename Component::subject_type, Context> {};
+    }
+    
+    template <typename Component, typename Context, typename Enable>
+    struct has_attribute : detail::default_has_attribute<Component, Context> {};
+
+}}}}
+
+#endif