From the error it looks like you're placing the child class within the parent class like so:

class Doclf_usersController extends \Joomla\CMS\MVC\Controller\BaseController
{
    class DivStyle extends Doclf_usersController
    {
    }
}

But it should be outside and, ideally, in a separate file.

From the error it looks like you're placing the child class within the parent class like so:

class Doclf_usersController extends \Joomla\CMS\MVC\Controller\BaseController
{
    class DivStyle extends Doclf_usersController
    {
    }
}

But it should be outside and, ideally, in a separate file.

If you want to keep both classes in the same file for some reason, it should be like this:

class Doclf_usersController extends \Joomla\CMS\MVC\Controller\BaseController
{
    // Parent class code.
}

class DivStyle extends Doclf_usersController
{
    // Child class code.
}