From b7fb20e69a29b1290231d8477019a1ce922a2dd1 Mon Sep 17 00:00:00 2001
From: Christopher Schmidt <mr.chr.schmidt@online.de>
Date: Sun, 25 Sep 2011 17:36:13 +0000
Subject: [PATCH] Fusion: updates

[SVN r74566]
---
 include/boost/fusion/support/tag_of.hpp     | 12 +++++++++---
 include/boost/fusion/support/tag_of_fwd.hpp |  3 +++
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/include/boost/fusion/support/tag_of.hpp b/include/boost/fusion/support/tag_of.hpp
index 187467c5..5df9e84a 100644
--- a/include/boost/fusion/support/tag_of.hpp
+++ b/include/boost/fusion/support/tag_of.hpp
@@ -50,11 +50,17 @@ namespace boost { namespace fusion
 
     namespace traits
     {
+        template <typename Sequence, typename Active>
+        struct tag_of_fallback
+        {
+            typedef non_fusion_tag type;
+        };
+
         template <typename Sequence, typename Active>
         struct tag_of
-          : mpl::if_< fusion::detail::is_mpl_sequence<Sequence>,
-              mpl::identity<mpl_sequence_tag>,
-              mpl::identity<non_fusion_tag> >::type
+          : mpl::eval_if< fusion::detail::is_mpl_sequence<Sequence>,
+              mpl::identity<mpl::identity<mpl_sequence_tag> >,
+              tag_of_fallback<Sequence> >::type
         {};
 
         template <typename Sequence>
diff --git a/include/boost/fusion/support/tag_of_fwd.hpp b/include/boost/fusion/support/tag_of_fwd.hpp
index ba434d93..dfc0e01c 100644
--- a/include/boost/fusion/support/tag_of_fwd.hpp
+++ b/include/boost/fusion/support/tag_of_fwd.hpp
@@ -12,6 +12,9 @@ namespace boost { namespace fusion
 {
     namespace traits
     {
+        template <typename Sequence, typename Active = void>
+        struct tag_of_fallback;
+
         template<typename T, typename Active = void>
         struct tag_of;
     }