GNU bug report logs - #52378
28.0.50; [PATCH] Reinstate a guard on compute_window_start()

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: dick.r.chiang <at> gmail.com
To: bug-gnu-emacs <bug-gnu-emacs <at> gnu.org>
Subject: 28.0.50; [PATCH] Reinstate a guard on compute_window_start()
Date: Wed, 08 Dec 2021 16:14:27 -0500

[0001-A-common-error.patch (text/x-diff, inline)]

From c0d3b2f75cd1ef0d4b45442ab073d8cd0a448a08 Mon Sep 17 00:00:00 2001
From: dickmao <dick.r.chiang <at> gmail.com>
Date: Wed, 8 Dec 2021 16:11:34 -0500
Subject: [PATCH] A common error

* src/xdisp.c (compute_window_start_on_continuation_line):
Align code with comment.
---
 src/xdisp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/xdisp.c b/src/xdisp.c
index 0ff6286af74..0fed93106df 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -18088,7 +18088,7 @@ compute_window_start_on_continuation_line (struct window *w)
          case point will not be visible with any window start we
          compute.  */
       if (IT_CHARPOS (it) <= PT
-	  || (CHARPOS (start_pos) - IT_CHARPOS (it)
+	  && (CHARPOS (start_pos) - IT_CHARPOS (it)
 	      /* PXW: Do we need upper bounds here?  */
 	      < WINDOW_TOTAL_LINES (w) * WINDOW_TOTAL_COLS (w)))
 	{
-- 
2.26.2

[Message part 2 (text/plain, inline)]

In Commercial Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30, cairo version 1.15.10)
 of 2021-12-04 built on dick
Repository revision: 9d9fe19c6ceb78c6f14d4bfb1fb85d6356b7e0f6
Repository branch: dev
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
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Message #10 received at 52378-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: dick.r.chiang <at> gmail.com
Cc: 52378-done <at> debbugs.gnu.org
Subject: Re: bug#52378: 28.0.50;
 [PATCH] Reinstate a guard on compute_window_start()
Date: Thu, 09 Dec 2021 09:22:33 +0200

> From: dick.r.chiang <at> gmail.com
> Date: Wed, 08 Dec 2021 16:14:27 -0500
> 
> >From c0d3b2f75cd1ef0d4b45442ab073d8cd0a448a08 Mon Sep 17 00:00:00 2001
> From: dickmao <dick.r.chiang <at> gmail.com>
> Date: Wed, 8 Dec 2021 16:11:34 -0500
> Subject: [PATCH] A common error
> 
> * src/xdisp.c (compute_window_start_on_continuation_line):
> Align code with comment.

The current code is correct.  It's the comment that might confuse: it
describes the conditions under which we do NOT want to execute the
code in the following block (that's what "give up" means in this
case).  So "||" is correct, and you need to reverse the conditions to
understand what the comment says.  For example, it says "too far", but
the condition says "less than", not "greater than".

I tried to clarify the comment on the release branch.

Message #13 received at 52378 <at> debbugs.gnu.org (full text, mbox):

From: dick <dick.r.chiang <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 52378 <at> debbugs.gnu.org, 52378-done <at> debbugs.gnu.org
Subject: Re: bug#52378: 28.0.50; [PATCH] Reinstate a guard on
 compute_window_start()
Date: Thu, 09 Dec 2021 04:49:01 -0500

> The current code is correct.

I don't mind the DeMorgan's errors of this kind; I am guilty of them
too.  What I do mind is willful incompetence.

Message #19 received at 52378 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: 52378 <at> debbugs.gnu.org
Cc: dick.r.chiang <at> gmail.com
Subject: Re: bug#52378: 28.0.50;
 [PATCH] Reinstate a guard on compute_window_start()
Date: Thu, 09 Dec 2021 21:31:22 +0200

> Date: Thu, 09 Dec 2021 09:22:33 +0200
> From: Eli Zaretskii <eliz <at> gnu.org>
> Cc: 52378-done <at> debbugs.gnu.org
> 
> > From: dick.r.chiang <at> gmail.com
> > Date: Wed, 08 Dec 2021 16:14:27 -0500
> > 
> > >From c0d3b2f75cd1ef0d4b45442ab073d8cd0a448a08 Mon Sep 17 00:00:00 2001
> > From: dickmao <dick.r.chiang <at> gmail.com>
> > Date: Wed, 8 Dec 2021 16:11:34 -0500
> > Subject: [PATCH] A common error
> > 
> > * src/xdisp.c (compute_window_start_on_continuation_line):
> > Align code with comment.
> 
> The current code is correct.  It's the comment that might confuse:

Actually, I take that back.  You were right.  I installed the change.

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