The following fails to compile on both g++ 4.8.2 and VS2005 using Boost 1.56: #include #include struct MOC { MOC() : value(121) {} MOC(BOOST_RV_REF(MOC) rhs) : value(rhs.value) {} int value; private: //Declared and purposefully not defined. MOC & operator=(MOC); private: BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) }; MOC moveonlyMutableRValue() { return MOC(); } MOC const moveonlyConstRValue() { return MOC(); } int main() { MOC m(moveonlyConstRValue()); return 0; } with g++, I get the following error messages: boost_move_const_rvalue.cc: In function ‘int main()’: boost_move_const_rvalue.cc:28:30: error: invalid user-defined conversion from ‘const MOC’ to ‘boost::rv<MOC>&’ [-fpermissive] MOC m(moveonlyConstRValue()); ^ In file included from boost_move_const_rvalue.cc:1:0: /home/HPC/boost_installed/v1_56_0/include/boost/move/core.hpp:219:7: note: candidate is: MOC::operator boost::rv<MOC>&() <near match> operator ::boost::rv<TYPE>&() \ ^ boost_move_const_rvalue.cc:13:3: note: in expansion of macro ‘BOOST_MOVABLE_BUT_NOT_COPYABLE’ BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) ^ /home/HPC/boost_installed/v1_56_0/include/boost/move/core.hpp:219:7: note: no known conversion for implicit ‘this’ parameter from ‘const MOC*’ to ‘MOC*’ operator ::boost::rv<TYPE>&() \ ^ boost_move_const_rvalue.cc:13:3: note: in expansion of macro ‘BOOST_MOVABLE_BUT_NOT_COPYABLE’ BOOST_MOVABLE_BUT_NOT_COPYABLE(MOC) ^ boost_move_const_rvalue.cc:28:30: error: passing ‘const MOC’ as ‘this’ argument of ‘MOC::operator boost::rv<MOC>&()’ discards qualifiers [-fpermissive] MOC m(moveonlyConstRValue());