Added BOOST_MOVE_RET

include/boost/move/core.hpp

@@ -168,6 +168,46 @@
       const ::boost::rv< TYPE >& \
    //
 
+   namespace boost {
+   namespace move_detail {
+
+   template <class Ret, class T>
+   inline typename ::boost::move_detail::enable_if_c
+      <  ::boost::move_detail::is_lvalue_reference<Ret>::value ||
+        !::boost::has_move_emulation_enabled<T>::value
+      , T&>::type
+         move_return(T& x) BOOST_NOEXCEPT
+   {
+      return x;
+   }
+
+   template <class Ret, class T>
+   inline typename ::boost::move_detail::enable_if_c
+      < !::boost::move_detail::is_lvalue_reference<Ret>::value &&
+         ::boost::has_move_emulation_enabled<T>::value
+      , ::boost::rv<T>&>::type
+         move_return(T& x) BOOST_NOEXCEPT
+   {
+      return *static_cast< ::boost::rv<T>* >(::boost::move_detail::addressof(x));
+   }
+
+   template <class Ret, class T>
+   inline typename ::boost::move_detail::enable_if_c
+      < !::boost::move_detail::is_lvalue_reference<Ret>::value &&
+         ::boost::has_move_emulation_enabled<T>::value
+      , ::boost::rv<T>&>::type
+         move_return(::boost::rv<T>& x) BOOST_NOEXCEPT
+   {
+      return x;
+   }
+
+   }  //namespace move_detail {
+   }  //namespace boost {
+
+   #define BOOST_MOVE_RET(RET_TYPE, REF)\
+      boost::move_detail::move_return< RET_TYPE >(REF)
+   //
+
    //////////////////////////////////////////////////////////////////////////////
    //
    //                         BOOST_MOVABLE_BUT_NOT_COPYABLE
@@ -220,9 +260,12 @@
       #elif defined(_MSC_VER) && (_MSC_VER == 1600)
          //Standard rvalue binding rules but with some bugs
          #define BOOST_MOVE_MSVC_10_MEMBER_RVALUE_REF_BUG
+         #define BOOST_MOVE_MSVC_AUTO_MOVE_RETURN_BUG
          //Use standard library for MSVC to avoid namespace issues as
          //some move calls in the STL are not fully qualified.
          //#define BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE
+      #elif defined(_MSC_VER) && (_MSC_VER == 1700)
+         #define BOOST_MOVE_MSVC_AUTO_MOVE_RETURN_BUG
       #endif
    #endif
 
@@ -298,7 +341,6 @@
    //
 
    #if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
-   /// @cond
 
    #define BOOST_RV_REF_2_TEMPL_ARGS(TYPE, ARG1, ARG2)\
       TYPE<ARG1, ARG2> && \
@@ -328,10 +370,69 @@
       const TYPE & \
    //
 
-   /// @endcond
 
    #endif   //#if !defined(BOOST_MOVE_DOXYGEN_INVOKED)
 
+   #if !defined(BOOST_MOVE_MSVC_AUTO_MOVE_RETURN_BUG) || defined(BOOST_MOVE_DOXYGEN_INVOKED)
+
+      //!This macro is used to achieve portable move return semantics.
+      //!The Standard allows implicit move returns when the object to be returned 
+      //!is designated by an lvalue and:
+      //!   - The criteria for elision of a copy operation are met OR
+      //!   - The criteria would be met save for the fact that the source object is a function parameter
+      //!
+      //!For C++11 conforming compilers this macros only yields to REF:
+      //! <code>return BOOST_MOVE_RET(RET_TYPE, REF);</code> -> <code>return REF;</code>
+      //!
+      //!For compilers without rvalue references
+      //!this macro does an explicit move if the move emulation is activated
+      //!and the return type (RET_TYPE) is not a reference.
+      //!
+      //!For non-conforming compilers with rvalue references like Visual 2010 & 2012,
+      //!an explicit move is performed if RET_TYPE is not a reference.
+      //!
+      //! <b>Caution</b>: When using this macro in a non-conforming or C++03
+      //!compilers, a move will be performed even if the C++11 standard does not allow it
+      //!(e.g. returning a static variable). The user is responsible for using this macro
+      //!only used to return local objects that met C++11 criteria.
+      #define BOOST_MOVE_RET(RET_TYPE, REF)\
+         (REF)
+      //
+
+   #else //!defined(BOOST_MOVE_MSVC_AUTO_MOVE_RETURN_BUG) || defined(BOOST_MOVE_DOXYGEN_INVOKED)
+
+      #include <boost/move/detail/meta_utils.hpp>
+
+      namespace boost {
+      namespace move_detail {
+
+      template <class Ret, class T>
+      inline typename ::boost::move_detail::enable_if_c
+         <  ::boost::move_detail::is_lvalue_reference<Ret>::value
+         , T&>::type
+            move_return(T& x) BOOST_NOEXCEPT
+      {
+         return x;
+      }
+
+      template <class Ret, class T>
+      inline typename ::boost::move_detail::enable_if_c
+         < !::boost::move_detail::is_lvalue_reference<Ret>::value
+         , Ret && >::type
+            move_return(T&& t) BOOST_NOEXCEPT
+      {
+         return static_cast< Ret&& >(t);
+      }
+
+      }  //namespace move_detail {
+      }  //namespace boost {
+
+      #define BOOST_MOVE_RET(RET_TYPE, REF)\
+         boost::move_detail::move_return< RET_TYPE >(REF)
+      //
+
+   #endif   //!defined(BOOST_MOVE_MSVC_AUTO_MOVE_RETURN_BUG) || defined(BOOST_MOVE_DOXYGEN_INVOKED)
+
 #endif   //BOOST_NO_CXX11_RVALUE_REFERENCES
 
 #include <boost/move/detail/config_end.hpp>