From 630ab2aae4ab4377f858d80302a3c0bbd26b8f79 Mon Sep 17 00:00:00 2001
From: Glen Fernandes <glen.fernandes@gmail.com>
Date: Sun, 8 Jul 2018 10:52:35 -0400
Subject: [PATCH] Workaround MSVC10 and MSVC11 for exchange

---
 include/boost/core/exchange.hpp | 52 +++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 18 deletions(-)

diff --git a/include/boost/core/exchange.hpp b/include/boost/core/exchange.hpp
index c31f2af..89d95fe 100644
--- a/include/boost/core/exchange.hpp
+++ b/include/boost/core/exchange.hpp
@@ -10,12 +10,45 @@ Distributed under the Boost Software License, Version 1.0.
 
 #include <boost/config.hpp>
 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#include <boost/config/workaround.hpp>
 #include <utility>
 #endif
 
 namespace boost {
+namespace detail {
 
-#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+template<class T>
+struct exchange_type {
+    typedef T type;
+};
+
+} /* detail */
+
+#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+template<class T>
+inline T exchange(T& t, const typename detail::exchange_type<T>::type& u)
+{
+    T v = t;
+    t = u;
+    return v;
+}
+#elif BOOST_WORKAROUND(BOOST_MSVC, < 1800)
+template<class T>
+inline T exchange(T& t, const typename detail::exchange_type<T>::type& u)
+{
+    T v = std::move(t);
+    t = u;
+    return v;
+}
+
+template<class T>
+inline T exchange(T& t, typename detail::exchange_type<T>::type&& u)
+{
+    T v = std::move(t);
+    t = std::move(u);
+    return v;
+}
+#else
 template<class T, class U = T>
 BOOST_CXX14_CONSTEXPR inline T exchange(T& t, U&& u)
 {
@@ -23,23 +56,6 @@ BOOST_CXX14_CONSTEXPR inline T exchange(T& t, U&& u)
     t = std::forward<U>(u);
     return v;
 }
-#else
-namespace detail {
-
-template<class T>
-struct exchanger {
-    typedef T type;
-};
-
-} /* detail */
-
-template<class T>
-inline T exchange(T& t, const typename detail::exchanger<T>::type& u)
-{
-    T v = t;
-    t = u;
-    return v;
-}
 #endif
 
 } /* boost */