Subject: Re: bug#49277: 28.0.50; [PATCH] Fix ediff3 with window-combinaison-resize

From: marmote-te <[email-masked]>
Date: Thu, 08 Jul 2021 15:33:50 +0200

martin rudalics <[email-masked]> writes:

>> I have a bug when calling ediff3, the layout is not a balanced.
>>
>> Ultimately I found that combining this settings were the culprit :
>>
>> (setq window-combination-resize t
>>        even-window-sizes nil)
>>
>> ;; you can test it with eg :
>> (setq default-directory "/home/user")
>> (ediff3 ".bashrc"
>>          ".bash_history"
>>          ".bash_logout")
>>
>> Removing the manual resizing when splitting windows and relying rather
>> on 'window-combinaison-resize' to balance the layout, solve the issue.
>
> I think we can easily do that but it does not handle the
>
> (setq window-combination-resize t
>       even-window-sizes nil
>       ediff-window-setup-function 'ediff-setup-windows-plain)
>
> case here.  Shouldn't we fix that too?
>
> Thanks, martin

Yes, I missed that one ; it worked only in plain window with
(setq ediff-split-window-function #'split-window-horizontally)

I guess that is the control buffer that is interfering somehow
with the resizing ?

I tried to apply on it a 'window-preserve parameter on its window,
without much success.

So in this one, for the plain window setup, I only create the control
window at the end of the layout.
It does not seemed necessary to setup the control buffer twice.

>From 96b03d92ea2c46d5cb9716383ad2248a3d701c72 Mon Sep 17 00:00:00 2001
From: Trust me I am a doctor <[email-masked]>
Date: Tue, 29 Jun 2021 19:22:04 +0200
Subject: [PATCH] Fix ediff3 with window-combinaison-resize

* lisp/vc/ediff-wind.el (ediff-setup-windows-plain-compare): When
'window-combination-resize' is set to t and 'even-window-sizes'
is set to nil, the 3 window layout as in ediff3 does not produce
a balanced layout. Getting rid of the manual resizing and relying
rather on window.el to automatically resize the windows with
'window-combination-resize', solve that issue.
(ediff-setup-windows-multiframe-compare): Tiddo.
---
 lisp/vc/ediff-wind.el | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/lisp/vc/ediff-wind.el b/lisp/vc/ediff-wind.el
index fc6ea944ae..7c90348b5d 100644
--- a/lisp/vc/ediff-wind.el
+++ b/lisp/vc/ediff-wind.el
@@ -400,7 +400,8 @@ ediff-setup-windows-plain-compare
   ;; skip dedicated and unsplittable frames
   (ediff-destroy-control-frame control-buffer)
   (let ((window-min-height 1)
-	split-window-function wind-width-or-height
+        (window-combination-resize t)
+	split-window-function
 	three-way-comparison
 	wind-A-start wind-B-start wind-A wind-B wind-C)
     (with-current-buffer control-buffer
@@ -419,22 +420,12 @@ ediff-setup-windows-plain-compare
 	(select-window (next-window nil 'ignore-minibuf)))
     (delete-other-windows)
     (set-window-dedicated-p (selected-window) nil)
-    (split-window-vertically)
-    (ediff-select-lowest-window)
-    (ediff-setup-control-buffer control-buffer)
 
     ;; go to the upper window and split it betw A, B, and possibly C
     (other-window 1)
     (switch-to-buffer buf-A)
     (setq wind-A (selected-window))
-    (if three-way-comparison
-	(setq wind-width-or-height
-	      (/ (if (eq split-window-function #'split-window-vertically)
-		     (window-height wind-A)
-		   (window-width wind-A))
-		 3)))
-
-    (funcall split-window-function wind-width-or-height)
+    (funcall split-window-function)
 
     (if (eq (selected-window) wind-A)
 	(other-window 1))
@@ -443,7 +434,7 @@ ediff-setup-windows-plain-compare
 
     (if three-way-comparison
 	(progn
-	  (funcall split-window-function) ; equally
+	  (funcall split-window-function)
 	  (if (eq (selected-window) wind-B)
 	      (other-window 1))
 	  (switch-to-buffer buf-C)
@@ -461,7 +452,9 @@ ediff-setup-windows-plain-compare
 	  (set-window-start wind-A wind-A-start)
 	  (set-window-start wind-B wind-B-start)))
 
-    (ediff-select-lowest-window)
+    (select-window (display-buffer-in-direction
+                    control-buffer
+                    '((direction . bottom))))
     (ediff-setup-control-buffer control-buffer)
     ))
 
@@ -746,6 +739,7 @@ ediff-setup-windows-multiframe-compare
 			     (and (not (frame-live-p frame-A))
 				  (or ctl-frame-exists-p
 				      (eq frame-B (selected-frame))))))
+         (window-combination-resize t)
 	 wind-A-start wind-B-start
 	 designated-minibuffer-frame)
 
@@ -758,7 +752,7 @@ ediff-setup-windows-multiframe-compare
 			   'B ediff-narrow-bounds))))
 
     (if use-same-frame
-	(let (wind-width-or-height) ; this affects 3way setups only
+        (progn
 	  (if (and (eq frame-A frame-B) (frame-live-p frame-A))
 	      (select-frame frame-A)
 	    ;; avoid dedicated and non-splittable windows
@@ -767,15 +761,7 @@ ediff-setup-windows-multiframe-compare
 	  (switch-to-buffer buf-A)
 	  (setq wind-A (selected-window))
 
-	  (if three-way-comparison
-	      (setq wind-width-or-height
-		    (/
-		     (if (eq split-window-function #'split-window-vertically)
-			 (window-height wind-A)
-		       (window-width wind-A))
-		     3)))
-
-	  (funcall split-window-function wind-width-or-height)
+          (funcall split-window-function)
 	  (if (eq (selected-window) wind-A)
 	      (other-window 1))
 	  (switch-to-buffer buf-B)
-- 
2.20.1

There is also the merge job layouts, that are a little bit different,
but as far I understand them, they are not affected by this issue. If it
feels cleaner, I could however apply the same modification to the setup
of the control buffer.

--