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

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> Date: [04-28-2020 12:15:24] <28 Apr 2020 22:15:24 +0300>
> From: Eli Zaretskii <address@hidden>
> To: Keith David Bershatsky <address@hidden>
> Cc: address@hidden
> 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 <address@hidden>
> >
> > 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.