bug#51993: 29.0.50; [PATCH for 29.1] Killing emacsclient terminal with `server-stop-automatically' doesn't prompt to save files

[Jim Porter <jporterbugs@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 2721 bytes --]

On 12/1/2022 9:29 AM, Eli Zaretskii wrote:
>> Date: Mon, 28 Nov 2022 21:31:02 -0800
>> From: Jim Porter <jporterbugs@gmail.com>
>> Cc: larsi@gnus.org, 51993@debbugs.gnu.org, gregory@heytings.org
>>
>>>>> The issue in the quote above is that if you enable automatic server
>>>>> shutdown in Emacs 29, it changes the behavior of exiting an emacsclient
>>>>> even when it wouldn't stop the server (i.e. when there are other active
>>>>> clients). That's surprising to me, I wouldn't expect that setting to
>>>>> affect cases when it decides *not* to kill the Emacs daemon.
>>>>
>>>> Sounds like a bug to me, because it contradicts what the doc string
>>>> says.
>>>
>>> That's how it seems to me too. ...
>> Ok, after quite a delay, here's a patch for this. Previously, the
>> function 'server-stop-automatically--handle-delete-frame' responded to
>> both 'C-x C-c' ('save-buffers-kill-terminal') and 'delete-frame', which
>> made it more complex. I've moved the 'C-x C-c' case into
>> 'server-save-buffers-kill-terminal', which simplifies
>> 'server-stop-automatically--handle-delete-frame'.
>>
>> The updated 'server-save-buffers-kill-terminal' should now make sure
>> that the new stop-automatically behavior only happens when there are no
>> other client processes (or nowait frames).
> 
> We want this on the release branch, right?  Then please make it the minimal
> change which fixes the immediate cause of the bug, and does nothing else: no
> refactoring, no reshuffling of the code or making it nicer or less
> complicated -- all that just makes the risk of new bugs higher and the job
> of reviewing the patch harder.

Thanks for taking a look. I believe we'd want this on the release 
branch. Here's the absolute minimum I could manage, although it doesn't 
quite fix everything that my previous patch does. In particular, when 
server-stop-automatically is set to 'kill-terminal' (or 'delete-frame'):

* If you type 'C-x C-c' ('save-buffers-kill-terminal') in a nowait 
client frame, and there are still other (non-daemon) frames, nothing 
happens. You'd have to use 'C-x 5 0' ('delete-frame') instead. Fixing 
this would basically mean doing 90% of my original patch, so it's 
probably too risky.

* If you type 'C-u C-x C-c', it doesn't silently save all the relevant 
buffers. That's because 'server-save-buffers-kill-terminal' doesn't 
forward the prefix arg to 
'server-stop-automatically--handle-delete-frame'. That's a separate (but 
closely related) bug, so I didn't fix that either.

In a followup message, I'll show the breakdown of my previous patch into 
smaller steps with some more detailed explanation of why I think it 
simplifies things enough to be worth making the change on the master branch.

[-- Attachment #2: 0001-Make-killing-a-non-last-client-work-the-same-no-matt.patch --]
[-- Type: text/plain, Size: 3279 bytes --]

From 198f98b43d5dde34775010ac987d31e90745381f Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Thu, 1 Dec 2022 16:46:57 -0800
Subject: [PATCH] Make killing a non-last client work the same no matter the
 auto-stop setting

Do not merge to master.  (This is a minimal change for the release
branch, and will be fixed in a cleaner way on master.)

Previously, if 'server-stop-automatically' was configured for
'kill-terminal' or 'delete-frame', killing a client via
'save-buffers-kill-terminal' wouldn't prompt about the saving files in
the client's buffer list (as it does when not using those settings).
This change ensures that those settings only apply when killing the
last client, as described in the manual (bug#51993).

* lisp/server.el (server-stop-automatically--handle-delete-frame):
When called by 'save-buffers-kill-terminal', first check to see
whether we'll want to kill Emacs, and if not, call 'save-some-buffers'
and 'server-delete-client', as in 'server-save-buffers-kill-terminal'.
---
 lisp/server.el | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/lisp/server.el b/lisp/server.el
index 1b027f88ce..0657af1f98 100644
--- a/lisp/server.el
+++ b/lisp/server.el
@@ -1809,19 +1809,32 @@ server-stop-automatically--handle-delete-frame
   (when server-stop-automatically
     (if (if (and (processp (frame-parameter frame 'client))
 		 (eq this-command 'save-buffers-kill-terminal))
-	    (progn
-	      (dolist (f (frame-list))
-		(when (and (eq (frame-parameter frame 'client)
-			       (frame-parameter f 'client))
-			   (not (eq frame f)))
-		  (set-frame-parameter f 'client nil)
-		  (let ((server-stop-automatically nil))
-		    (delete-frame f))))
-	      (if (cddr (frame-list))
-		  (let ((server-stop-automatically nil))
-		    (delete-frame frame)
-		    nil)
-		t))
+            (let* ((proc (frame-parameter frame 'client))
+                   ;; Keep the server alive if...
+                   (keep-server-alive-p
+                    (or
+                     ;; a) there are any other clients, or...
+                     (length> server-clients 1)
+                     ;; b) there are any frames not owned by this
+                     ;; client.
+                     (seq-some
+                      (lambda (frame)
+                        (when-let ((p (frame-parameter frame 'client)))
+                          (not (eq proc p))))
+                      (frame-list)))))
+              (when keep-server-alive-p
+                ;; If we want to keep the server alive, don't kill
+                ;; Emacs.  Instead, just call `save-some-buffers' and
+                ;; delete the client, as in
+                ;; `server-save-buffers-kill-terminal' above.
+                (let ((buffers (process-get proc 'buffers)))
+	          (save-some-buffers
+                   nil (if buffers
+                           (lambda () (memq (current-buffer) buffers))))
+	          (server-delete-client proc)))
+              ;; Tell the outer `if' block whether we want to kill
+              ;; Emacs.
+              (not keep-server-alive-p))
 	  (null (cddr (frame-list))))
 	(let ((server-stop-automatically nil))
 	  (save-buffers-kill-emacs)
-- 
2.25.1