promise_handler( use_future_t<Alloc> uf ) : promise_( std::allocate_shared<std::promise<void>>( typename Alloc::template rebind<char>::other( uf.get_allocator( ) ), std::allocator_arg, typename Alloc::template rebind<char>::other( uf.get_allocator( ) ) ) ) { }
promise_handler(use_future_t<Allocator> uf) : promise_(std::allocate_shared<std::promise<void> >( uf.get_allocator(), std::allocator_arg, uf.get_allocator())) { }