code: public static function fillToSize(&$array, $size, $fill)
      {
          $cnt = \count($array);
          if ($cnt >= $size) {
              return;
          }
          $array = array_merge($array, array_fill($cnt + 1, $size - $cnt, $fill));
      }
docs: Extend array to desired size by filling it with fill data
  
  @param array $array Array to fill
  @param int $size Desired size
  @param mixed $fill Fill data