I have an existing code for an application that uses BOOST_DETAIL_SPINLOCK_INIT from boost/smart_ptr/detail/spinlock.hpp. It is all fine when using with boost ver 1.53. I am trying to migrate to boost ver 1.66 and now this compilation fails. To isolate the issue, I have a sample program: #include <iostream> #include class BoostTest { public: BoostTest(int v): val(v), bLock(BOOST_DETAIL_SPINLOCK_INIT) { std::cout << "constructor called" << std::endl; } int getValue() { std::cout << "getValue() called" << std::endl; return val; } private: int val; boost::detail::spinlock bLock; }; int main() { std::cout << "starting test" << std::endl; BoostTest bt(10); std::cout << "value now " << bt.getValue() << std::endl; } With ver 1.66, it now gives me the error. Why this error after upgrade to 1.66? How do I correct it? $ g++ -std=c++11 -I/data/hdd/code/mgmt/common/external/boost/ifc/dist/include -c boosttest.cc boosttest.cc: In constructor 'BoostTest::BoostTest(int)': boosttest.cc:6:63: error: use of deleted function 'boost::detail::spinlock::spinlock(boost::detail::spinlock&&)' BoostTest(int v): val(v), bLock(BOOST_DETAIL_SPINLOCK_INIT) { ^ In file included from /data/hdd/code/mgmt/common/external/boost/ifc/dist/include/boost/smart_ptr/detail/spinlock.hpp:47:0, from boosttest.cc:2: /data/hdd/code/mgmt/common/external/boost/ifc/dist/include/boost/smart_ptr/detail/spinlock_std_atomic.hpp:27:7: note: 'boost::detail::spinlock::spinlock(boost::detail::spinlock&&)' is implicitly deleted because the default definition would be ill-formed: class spinlock ^ /data/hdd/code/mgmt/common/external/boost/ifc/dist/include/boost/smart_ptr/detail/spinlock_std_atomic.hpp:27:7: error: use of deleted function 'std::atomic_flag::atomic_flag(const std::atomic_flag&)' In file included from /usr/include/c++/4.8/atomic:41:0, from /data/hdd/code/mgmt/common/external/boost/ifc/dist/include/boost/smart_ptr/detail/spinlock_std_atomic.hpp:19, from /data/hdd/code/mgmt/common/external/boost/ifc/dist/include/boost/smart_ptr/detail/spinlock.hpp:47, from boosttest.cc:2: /usr/include/c++/4.8/bits/atomic_base.h:275:5: error: declared here atomic_flag(const atomic_flag&) = delete; ^