master 0a68159: Fix `quit-restore-window' when all previous buffers got killed (Bug#48367)

[Martin Rudalics]

branch: master
commit 0a681590268a4039f95a5a919b6b6d4f4e880d4c
Author: pillule <pillule@riseup.net>
Commit: Martin Rudalics <rudalics@gmx.at>

    Fix `quit-restore-window' when all previous buffers got killed (Bug#48367)
    
    * lisp/window.el (quit-restore-window): Simplify calculation of
    WINDOW's previous buffer.  Avoid that killing WINDOW's previous
    buffers results in a state where `quit-window' has no more
    effect, by simply deleting WINDOW in that case (Bug#48367).
    
    Copyright-paperwork-exempt: yes
---
 lisp/window.el | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/lisp/window.el b/lisp/window.el
index 8928308..026cde5 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -5036,14 +5036,10 @@ nil means to not handle the buffer in a particular way. 
 This
   (setq window (window-normalize-window window t))
   (let* ((buffer (window-buffer window))
         (quit-restore (window-parameter window 'quit-restore))
-        (prev-buffer
-         (let* ((prev-buffers (window-prev-buffers window))
-                (prev-buffer (caar prev-buffers)))
-           (and (or (not (eq prev-buffer buffer))
-                    (and (cdr prev-buffers)
-                         (not (eq (setq prev-buffer (cadr prev-buffers))
-                                  buffer))))
-                prev-buffer)))
+         (prev-buffer (catch 'prev-buffer
+                        (dolist (buf (window-prev-buffers window))
+                          (unless (eq (car buf) buffer)
+                            (throw 'prev-buffer (car buf))))))
         quad entry)
     (cond
      ((and (not prev-buffer)
@@ -5114,7 +5110,10 @@ nil means to not handle the buffer in a particular way.  
This
       (set-window-parameter window 'quit-restore nil)
       ;; Make sure that WINDOW is no more dedicated.
       (set-window-dedicated-p window nil)
-      (switch-to-prev-buffer window bury-or-kill)))
+      (if prev-buffer
+          (switch-to-prev-buffer window bury-or-kill)
+        ;; Delete WINDOW if there is no previous buffer (Bug#48367).
+        (window--delete window nil (eq bury-or-kill 'kill)))))
 
     ;; Deal with the buffer.
     (cond