xdisp.c: Suggestion to delete a few unused lines of code ...

xdisp.c: Suggestion to delete a few unused lines of code ...

[Keith David Bershatsky]

In the function display_line within xdisp.c, there is the following code set forth below.  Inasmuch as the first main condition is whether (line_number_needed), the second test within the ELSE IF statement for whether (line_number_needed) will always be negative; i.e., it would have to be negative or else we would never have gotten to the ELSE IF statement ... since the test will always be negative, Emacs will never call maybe_produce_line_number within the ELSE IF section of this code.

      /* Produce line number, if needed.  */
      if (line_number_needed)
	maybe_produce_line_number (it);
    }
  else if (it->area == TEXT_AREA)
    {

/* ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; */
/* SUGGESTED DELETION */

      /* Line numbers should precede the line-prefix or wrap-prefix.  */
      if (line_number_needed)
	maybe_produce_line_number (it);

/* ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; */

      /* We only do this when not calling move_it_in_display_line_to
	 above, because that function calls itself handle_line_prefix.  */
      handle_line_prefix (it);
    }
  else
    {
      /* Line-prefix and wrap-prefix are always displayed in the text
	 area.  But if this is the first call to display_line after
	 init_iterator, the iterator might have been set up to write
	 into a marginal area, e.g. if the line begins with some
	 display property that writes to the margins.  So we need to
	 wait with the call to handle_line_prefix until whatever
	 writes to the margin has done its job.  */
      pending_handle_line_prefix = true;
    }

Re: xdisp.c: Suggestion to delete a few unused lines of code ...

[Keith David Bershatsky]

Ooops ... never mind ... my eyes overlooked the closing brace:

          /* Produce line number, if needed.  */
          if (line_number_needed)
    maybe_produce_line_number (it);
===>    }
      else if (it->area == TEXT_AREA)
        {
    

Sorry for any inconvenience as to the erroneous suggestion .....

Keith

Re: xdisp.c: Suggestion to delete a few unused lines of code ...

[Eli Zaretskii]

> Date: Tue, 28 Apr 2020 11:46:26 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> In the function display_line within xdisp.c, there is the following code set forth below.  Inasmuch as the first main condition is whether (line_number_needed), the second test within the ELSE IF statement for whether (line_number_needed) will always be negative; i.e., it would have to be negative or else we would never have gotten to the ELSE IF statement ... since the test will always be negative, Emacs will never call maybe_produce_line_number within the ELSE IF section of this code.

I don't understand why you think the test will always be negative in
the second case.  The code is really

  bool line_number_needed = should_produce_line_number (it);

  if (it->current_x < it->first_visible_x + x_incr)
    {
      [...]
      if (line_number_needed)
	maybe_produce_line_number (it);
    }
  else if (it->area == TEXT_AREA)
    {
      if (line_number_needed)
	maybe_produce_line_number (it);
      [...]
    }

What this says that we may need to produce the line numbers both when
we start outside of the visible portion of the window (the 'if'
clause) and when we start inside the visible portion.

Re: xdisp.c: Suggestion to delete a few unused lines of code ...

[Keith David Bershatsky]

Thank you Eli for taking the time to review and respond to this particular thread.

You are absolutely correct!

I should have studied the code more ....

As always, your help is greatly appreciated!

Keith

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

> Date: [04-28-2020 12:15:24] <28 Apr 2020 22:15:24 +0300>
> From: Eli Zaretskii <eliz@gnu.org>
> To: Keith David Bershatsky <esq@lawlist.com>
> Cc: emacs-devel@gnu.org
> Subject: Re: xdisp.c:  Suggestion to delete a few unused lines of code ...
> 
> > Date: Tue, 28 Apr 2020 11:46:26 -0700
> > From: Keith David Bershatsky <esq@lawlist.com>
> >
> > In the function display_line within xdisp.c, there is the following code set forth below.  Inasmuch as the first main condition is whether (line_number_needed), the second test within the ELSE IF statement for whether (line_number_needed) will always be negative; i.e., it would have to be negative or else we would never have gotten to the ELSE IF statement ... since the test will always be negative, Emacs will never call maybe_produce_line_number within the ELSE IF section of this code.
> 
> I don't understand why you think the test will always be negative in
> the second case.  The code is really
> 
>   bool line_number_needed = should_produce_line_number (it);
> 
>   if (it->current_x < it->first_visible_x + x_incr)
>     {
>       [...]
>       if (line_number_needed)
> maybe_produce_line_number (it);
>     }
>   else if (it->area == TEXT_AREA)
>     {
>       if (line_number_needed)
> maybe_produce_line_number (it);
>       [...]
>     }
> 
> What this says that we may need to produce the line numbers both when
> we start outside of the visible portion of the window (the 'if'
> clause) and when we start inside the visible portion.