Eli Zaretskii <eliz@gnu.org> writes:

>> From: John Shahid <jvshahid@gmail.com>
>> Date: Thu, 28 Jun 2018 13:27:34 +0000
>> Cc: 31325@debbugs.gnu.org
>> 
>> >> 1. introduce a new lisp function for recentering and discourage the use
>> >> of `recenter' from lisp (i.e. declaring it `interactive-only'), or
>> >> 2. add a new `recenter-and-redisplay' and bound it to C-l
>> >> Also, Stefan's suggestion/possible solution:
>> >> 3. adding an argument to `recenter' to control the redisplay behavior
>> >
>> > Either of those is OK.  The benefit of the 3rd is that it would likely
>> > "magically fix" 99% of the existing uses (I'm thinking of adding an
>> > optional argument which we could call `and-redisplay` which when non-nil
>> > tells recenter to do a redisplay, so all existing Elisp calls would be
>> > implicitly modified not to cause a redisplay).
>> 
>> I ended up going with option 3. I also used `redisplay` instead of
>> `and-redisplay`. I felt the `and` is redundant, not sure how strongly
>> you feel about the name.
>
> Thanks, but please also include a NEWS entry announcing the change,
> and a suitable change for the ELisp manual.
>
> And I have a few comments:
>
>> -  (register Lisp_Object arg)
>> +  (register Lisp_Object arg, register Lisp_Object redisplay)
>
> I believe nowadays we remove the 'register' qualifiers whenever we
> change code that uses them.
>
>>  {
>>    struct window *w = XWINDOW (selected_window);
>>    struct buffer *buf = XBUFFER (w->contents);
>> @@ -5933,8 +5934,9 @@ and redisplay normally--don't erase and redraw the frame.  */)
>>  
>>    if (NILP (arg))
>>      {
>> -      if (!NILP (Vrecenter_redisplay)
>> -	  && (!EQ (Vrecenter_redisplay, Qtty)
>> +      if (!NILP (redisplay)
>> +	  && !NILP (Vrecenter_redisplay)
>> +	  && (!EQ (redisplay, Qtty)
>                    ^^^^^^^^^
> This should have been Vrecenter_redisplay, right?

fixed all the issues mentioned above in the attached patch and
documented the change in the NEWS file and the manual.

cheers,