From c01e7f7d00a5b0307edf8a6414d2780575393922 Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Wed, 12 Jul 2006 11:10:22 +0000
Subject: [PATCH] Undef macros before defining them (again).

[SVN r34511]
---
 .../type_traits/detail/bool_trait_def.hpp     | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/boost/type_traits/detail/bool_trait_def.hpp b/include/boost/type_traits/detail/bool_trait_def.hpp
index d6b024c..a54c910 100644
--- a/include/boost/type_traits/detail/bool_trait_def.hpp
+++ b/include/boost/type_traits/detail/bool_trait_def.hpp
@@ -17,6 +17,28 @@
 #include <boost/mpl/aux_/lambda_support.hpp>
 #include <boost/config.hpp>
 
+//
+// Unfortunately some libraries have started using this header without
+// cleaning up afterwards: so we'd better undef the macros just in case 
+// they've been defined already....
+//
+#ifdef BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL
+#undef BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL
+#undef BOOST_TT_AUX_BOOL_C_BASE
+#undef BOOST_TT_AUX_BOOL_TRAIT_DEF1
+#undef BOOST_TT_AUX_BOOL_TRAIT_DEF2
+#undef BOOST_TT_AUX_BOOL_TRAIT_SPEC1
+#undef BOOST_TT_AUX_BOOL_TRAIT_SPEC2
+#undef BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1
+#undef BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2
+#undef BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1
+#undef BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_2
+#undef BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1
+#undef BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_2
+#undef BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1
+#undef BOOST_TT_AUX_BOOL_TRAIT_CV_SPEC1
+#endif
+
 #if defined(__SUNPRO_CC) && (__SUNPRO_CC < 0x570)
 #   define BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(C) \
     typedef ::boost::integral_constant<bool,C> type; \