std::experimental::overaligned_tag, std::experimental::overaligned
From cppreference.com
                    
                                        
                    < cpp | experimental | simd
                    
                                                            
                    | Defined in header  <experimental/simd> | ||
| template < std::size_t N > struct overaligned_tag {}; | ||
This tag type indicates that the buffer of copy_from and copy_to is aligned to N.