On Boost 1.81 with clang 18 in C++ 23 mode: ``` [build] /usr/include/boost/fiber/future/detail/shared_state.hpp:160:19: warning: 'aligned_storage<4, 4>' is deprecated [-Wdeprecated-declarations] [build] 160 | typename std::aligned_storage< sizeof( R), alignof( R) >::type storage_{}; [build] | ^ [build] /usr/include/boost/fiber/future/promise.hpp:28:22: note: in instantiation of template class 'boost::fibers::detail::shared_state<int>' requested here [build] 28 | typedef typename shared_state< R >::ptr_type ptr_type; ``` It could have been fixed upstream since, I haven't checked. Niall