Why is it necessary for boost::atomic_shared_ptr

With the GCC 8.1 memory access feature -Werror=class-memaccess I got following error:

atomic_shared_ptr.hpp:84:20: error: ‘void* memcpy(void*, const void*, size_t)’ writing to an object of type ‘class boost::detail::spinlock’ with no trivial copy-assignment [-Werror=class-memaccess]
     std::memcpy( &l_, &init, sizeof( init ) );
     ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~