From e9f5ed41be7139fdaf62e928e75156cdc1cf09d9 Mon Sep 17 00:00:00 2001
From: Andrzej Krzemienski <akrzemi1@gmail.com>
Date: Tue, 13 May 2014 14:11:17 +0200
Subject: [PATCH] binding to rvalues can be reenabled with a macro

---
 include/boost/optional/optional.hpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/boost/optional/optional.hpp b/include/boost/optional/optional.hpp
index 72f5ab9..57fa522 100644
--- a/include/boost/optional/optional.hpp
+++ b/include/boost/optional/optional.hpp
@@ -175,9 +175,11 @@ struct types_when_is_ref
 template <class To, class From>
 void prevent_binding_rvalue_ref_to_optional_lvalue_ref()
 {
+#ifndef BOOST_OPTIONAL_ALLOW_BINDING_TO_RVALUES
   BOOST_STATIC_ASSERT_MSG(
     !boost::is_lvalue_reference<To>::value || !boost::is_rvalue_reference<From>::value, 
-    "binding rvalue references to optional lvalue references is disallowed"); 
+    "binding rvalue references to optional lvalue references is disallowed");
+#endif    
 }
 
 struct optional_tag {} ;