From 69409ed63a9e103e3e487a8ec0a2fd0e24ab9523 Mon Sep 17 00:00:00 2001
From: morinmorin <mimomorin@gmail.com>
Date: Fri, 30 Jun 2017 20:02:53 +0900
Subject: [PATCH] Make boost::distance traversal-category-aware (and constexpr
 in C++14)

---
 include/boost/range/distance.hpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/boost/range/distance.hpp b/include/boost/range/distance.hpp
index 075f2d1fb..8dcf05bc6 100644
--- a/include/boost/range/distance.hpp
+++ b/include/boost/range/distance.hpp
@@ -15,18 +15,19 @@
 # pragma once
 #endif
 
+#include <boost/iterator/distance.hpp>
 #include <boost/range/begin.hpp>
 #include <boost/range/end.hpp>
 #include <boost/range/difference_type.hpp>
 
-namespace boost 
+namespace boost
 {
 
     template< class T >
-    inline BOOST_DEDUCED_TYPENAME range_difference<T>::type 
+    inline BOOST_CXX14_CONSTEXPR BOOST_DEDUCED_TYPENAME range_difference<T>::type
     distance( const T& r )
     {
-        return std::distance( boost::begin( r ), boost::end( r ) );
+        return boost::distance( boost::begin( r ), boost::end( r ) );
     }
 
 } // namespace 'boost'