From e7b18513300006679f2b0d4ffe7fdc40ebff4656 Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Wed, 19 Jun 2013 17:37:17 +0000
Subject: [PATCH] Fix for #5809.

[SVN r84836]
---
 include/boost/type_traits/common_type.hpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/boost/type_traits/common_type.hpp b/include/boost/type_traits/common_type.hpp
index 00129d1..2d53c25 100644
--- a/include/boost/type_traits/common_type.hpp
+++ b/include/boost/type_traits/common_type.hpp
@@ -24,8 +24,10 @@
 #endif
 
 //----------------------------------------------------------------------------//
-#if defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) && !defined(BOOST_TYPEOF_SILENT)
-#define BOOST_TYPEOF_SILENT
+#if defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF)
+#  ifndef BOOST_TYPEOF_SILENT
+#     define BOOST_TYPEOF_SILENT
+#  endif
 #include <boost/typeof/typeof.hpp>   // boost wonders never cease!
 #endif