From c33857273550251284f20623b51b6ae0a119fe81 Mon Sep 17 00:00:00 2001
From: morinmorin <mimomorin@gmail.com>
Date: Sat, 16 Sep 2017 11:51:12 +0900
Subject: [PATCH] Fix usage of decltype-based result_of in transform_iterator.

Regardless of value categories of a transform_iterator object, its
dereference operator calls m_f as an lvalue. Thus, correct usage of
decltype-based result_of is result_of<const UnaryFunc&(...)>.
---
 include/boost/iterator/transform_iterator.hpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/boost/iterator/transform_iterator.hpp b/include/boost/iterator/transform_iterator.hpp
index 67356ff..2281df8 100644
--- a/include/boost/iterator/transform_iterator.hpp
+++ b/include/boost/iterator/transform_iterator.hpp
@@ -47,7 +47,11 @@ namespace iterators {
         // the function.
         typedef typename ia_dflt_help<
             Reference
+#ifdef BOOST_RESULT_OF_USE_TR1
           , result_of<const UnaryFunc(typename std::iterator_traits<Iterator>::reference)>
+#else
+          , result_of<const UnaryFunc&(typename std::iterator_traits<Iterator>::reference)>
+#endif
         >::type reference;
 
         // To get the default for Value: remove any reference on the