I created a class template where the template parameter, which is the size of the array, is used to create a static array of offsets (for offset_separator) in a static function (offsets()) returning a const reference to that local static array. I then call create offset_separator like this: offset_separator sep(offsets(), offsets+T); However, if I have observed it correctly, offset_separator (1.47.0) seems to copy the sequence of offsets into an internal vector. What's wrong with just using the passed array?