From 948271c0aea1b193bbba0c94bbe47898080f03d9 Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Thu, 5 Jan 2012 17:29:22 +0000
Subject: [PATCH] Fix Clang workaround. Fixes #6156.

[SVN r76323]
---
 include/boost/detail/fenv.hpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/boost/detail/fenv.hpp b/include/boost/detail/fenv.hpp
index 1ba8833..f048706 100644
--- a/include/boost/detail/fenv.hpp
+++ b/include/boost/detail/fenv.hpp
@@ -16,9 +16,10 @@
 
 /* If we're using clang + glibc, we have to get hacky. 
  * See http://llvm.org/bugs/show_bug.cgi?id=6907 */
-#if defined(__clang__)       &&                       \
+#if defined(__clang__)       &&  (__clang_major__ < 3) &&    \
     defined(__GNU_LIBRARY__) && /* up to version 5 */ \
-    defined(__GLIBC__)          /* version 6 + */
+    defined(__GLIBC__) &&         /* version 6 + */ \
+    !defined(_FENV_H)
   #define _FENV_H
 
   #include <features.h>