From 00db7a0829e49a9b1b264beb4cd247ea4dc3f944 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ion=20Gazta=C3=B1aga?= <igaztanaga@gmail.com>
Date: Thu, 21 Oct 2021 16:11:15 +0200
Subject: [PATCH] Fixes #42 ("<boost/move/unique_ptr.hpp> fails when
 BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE is set")

---
 doc/move.qbk                        |  1 +
 include/boost/move/utility_core.hpp | 75 +++++++++++++++--------------
 test/unique_ptr_std_move.cpp        | 30 ++++++++++++
 3 files changed, 70 insertions(+), 36 deletions(-)
 create mode 100644 test/unique_ptr_std_move.cpp

diff --git a/doc/move.qbk b/doc/move.qbk
index bb551f0..ec67b0c 100644
--- a/doc/move.qbk
+++ b/doc/move.qbk
@@ -806,6 +806,7 @@ Special thanks to:
 
 *  Fixed bugs:
    *  [@https://github.com/boostorg/move/issues/40 Git Issue #40: ['"Warning 4675 is not defined in MSVC"]].
+   *  [@https://github.com/boostorg/move/issues/42 Git Issue #42: ['"<boost/move/unique_ptr.hpp> fails when BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE is set"]].
 
 [endsect]
 
diff --git a/include/boost/move/utility_core.hpp b/include/boost/move/utility_core.hpp
index 55042a9..edc1a73 100644
--- a/include/boost/move/utility_core.hpp
+++ b/include/boost/move/utility_core.hpp
@@ -258,44 +258,47 @@
 
       #endif   //BOOST_MOVE_DOXYGEN_INVOKED
 
-      //////////////////////////////////////////////////////////////////////////////
-      //
-      //                         move_if_not_lvalue_reference
-      //
-      //////////////////////////////////////////////////////////////////////////////
-
-
-      #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
-         //! <b>Effects</b>: Calls `boost::move` if `input_reference` is not a lvalue reference.
-         //!   Otherwise returns the reference
-         template <class T> output_reference move_if_not_lvalue_reference(input_reference) noexcept;
-      #elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
-
-         //Old move approach, lvalues could bind to rvalue references
-
-         template <class T>
-         BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
-         {  return t;   }
-
-      #else //Old move
-
-         template <class T>
-         BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
-         {  return static_cast<T&&>(t);   }
-
-         template <class T>
-         BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
-         {
-            //"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
-            BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
-            return static_cast<T&&>(t);
-         }
-
-      #endif   //BOOST_MOVE_DOXYGEN_INVOKED
-
       }  //namespace boost {
 
-   #endif   //#if defined(BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE)
+   #endif   //BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE
+
+   //////////////////////////////////////////////////////////////////////////////
+   //
+   //                         move_if_not_lvalue_reference
+   //
+   //////////////////////////////////////////////////////////////////////////////
+
+   namespace boost {
+
+   #if defined(BOOST_MOVE_DOXYGEN_INVOKED)
+      //! <b>Effects</b>: Calls `boost::move` if `input_reference` is not a lvalue reference.
+      //!   Otherwise returns the reference
+      template <class T> output_reference move_if_not_lvalue_reference(input_reference) noexcept;
+   #elif defined(BOOST_MOVE_OLD_RVALUE_REF_BINDING_RULES)
+
+      //Old move approach, lvalues could bind to rvalue references
+
+      template <class T>
+      BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::identity<T>::type&& t) BOOST_NOEXCEPT
+      {  return t;   }
+
+   #else //Old move
+
+      template <class T>
+      BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type& t) BOOST_NOEXCEPT
+      {  return static_cast<T&&>(t);   }
+
+      template <class T>
+      BOOST_MOVE_FORCEINLINE T&& move_if_not_lvalue_reference(typename ::boost::move_detail::remove_reference<T>::type&& t) BOOST_NOEXCEPT
+      {
+         //"boost::forward<T> error: 'T' is a lvalue reference, can't forward as rvalue.";
+         BOOST_STATIC_ASSERT(!boost::move_detail::is_lvalue_reference<T>::value);
+         return static_cast<T&&>(t);
+      }
+
+   #endif   //BOOST_MOVE_DOXYGEN_INVOKED
+
+   }  //namespace boost {
 
 #endif   //BOOST_NO_CXX11_RVALUE_REFERENCES
 
diff --git a/test/unique_ptr_std_move.cpp b/test/unique_ptr_std_move.cpp
new file mode 100644
index 0000000..1985eb2
--- /dev/null
+++ b/test/unique_ptr_std_move.cpp
@@ -0,0 +1,30 @@
+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Howard Hinnant 2009
+// (C) Copyright Ion Gaztanaga 2014-2014.
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/move for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+#define BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE
+#include <boost/move/unique_ptr.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+////////////////////////////////
+//             main
+////////////////////////////////
+int main()
+{
+   //Just test compilation errors
+   boost::movelib::unique_ptr<int> a, b(boost::move(a));
+   BOOST_TEST(!(b.get() || a.get()));
+   b = boost::move(a);
+   b.release();
+   BOOST_TEST(!(b.get() || a.get()));
+   //Test results
+   return boost::report_errors();
+}