Subject: bug#57081: 29.0.50; [PATCH] Point associated with Window for good reasons

From: [email-masked]
Date: Tue, 09 Aug 2022 08:01:57 -0400

>From fc29004fe9287ce02eb3aa52abe5a4fc54834663 Mon Sep 17 00:00:00 2001
From: dickmao <[email-masked]>
Date: Tue, 9 Aug 2022 07:37:57 -0400
Subject: [PATCH] window-point is a thing

We regularly split the same buffer across two windows (C-x 2) and
position one window as a reference while manipulating the other.

When temporarily switching out one window, say to check a definition,
our flow gets wrecked by C-x b's refusal to flip back to the original
buffer since it's already displayed in another window, albeit, and
very importantly, at a different point (which to belabor things, is
the whole reason we want the same buffer in two windows).

I'm sure this has been proposed many times in the past, the
preservationist society being what it is.

* lisp/ido.el (ido-make-buffer-list-1): De-obfuscate.
(ido-make-buffer-list): Include visible buffer when switching.
(ido-get-buffers-in-frames): De-obfuscate.
* lisp/window.el (read-buffer-to-switch): Include visible buffer.
* test/lisp/ido-tests.el (ert-deftest): Test it.
---
 lisp/ido.el              | 43 +++++++++++++++++++---------------------
 lisp/window.el           |  2 +-
 test/lisp/ido-tests.el   | 21 ++++++++++++++++++++
 test/src/buffer-tests.el | 21 ++++++++++++++++++++
 4 files changed, 63 insertions(+), 24 deletions(-)

diff --git a/lisp/ido.el b/lisp/ido.el
index 134081d6759..5aeb8fcec51 100644
--- a/lisp/ido.el
+++ b/lisp/ido.el
@@ -3432,32 +3432,32 @@ ido-make-buffer-list-1
 	  (mapcar
 	   (lambda (x)
 	     (let ((name (buffer-name x)))
-	       (if (not (or (ido-ignore-item-p name ido-ignore-buffers) (member name visible)))
-		   name)))
+	       (and (not (ido-ignore-item-p name ido-ignore-buffers))
+                    (not (member name visible))
+	            name)))
 	   (buffer-list frame)))))
 
 (defun ido-make-buffer-list (default)
   "Return the current list of buffers.
-Currently visible buffers are put at the end of the list.
 The hook `ido-make-buffer-list-hook' is run after the list has been
 created to allow the user to further modify the order of the buffer names
 in this list.  If DEFAULT is non-nil, and corresponds to an existing buffer,
 it is put to the start of the list."
-  (let* ((ido-current-buffers (ido-get-buffers-in-frames 'current))
-	 (ido-temp-list (ido-make-buffer-list-1 (selected-frame) ido-current-buffers)))
-    (if ido-temp-list
-	(nconc ido-temp-list ido-current-buffers)
-      (setq ido-temp-list ido-current-buffers))
-    (if ido-predicate
-        (setq ido-temp-list (seq-filter
-                             (lambda (name)
-                               (funcall ido-predicate (cons name (get-buffer name))))
-                             ido-temp-list)))
-    (if default
-	(setq ido-temp-list
-	      (cons default (delete default ido-temp-list))))
-    (if (bound-and-true-p ido-enable-virtual-buffers)
-	(ido-add-virtual-buffers-to-list))
+  (let* ((current (buffer-name (window-buffer (selected-window))))
+         (ido-temp-list (ido-make-buffer-list-1 (selected-frame) (list current))))
+    (when (consp ido-temp-list)
+      (setcdr (last ido-temp-list) (list current)))
+    (when ido-predicate
+      (setq ido-temp-list
+            (seq-filter
+             (lambda (name)
+               (funcall ido-predicate (cons name (get-buffer name))))
+             ido-temp-list)))
+    (when default
+      (setq ido-temp-list
+	    (cons default (delete default ido-temp-list))))
+    (when (bound-and-true-p ido-enable-virtual-buffers)
+      (ido-add-virtual-buffers-to-list))
     (run-hooks 'ido-make-buffer-list-hook)
     ido-temp-list))
 
@@ -3723,11 +3723,8 @@ ido-get-buffers-in-frames
   "Return the list of buffers that are visible in the current frame.
 If optional argument CURRENT is given, restrict searching to the current
 frame, rather than all frames, regardless of value of `ido-all-frames'."
-  (let ((ido-bufs-in-frame nil))
-    (walk-windows 'ido-get-bufname nil
-		  (if current
-		      nil
-		    ido-all-frames))
+  (let (ido-bufs-in-frame)
+    (walk-windows 'ido-get-bufname nil (unless current ido-all-frames))
     ido-bufs-in-frame))
 
 (defun ido-get-bufname (win)
diff --git a/lisp/window.el b/lisp/window.el
index 4d88ffa9039..86996fe9730 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -8673,7 +8673,7 @@ read-buffer-to-switch
               (setq-local icomplete-with-completion-tables
                           (cons rbts-completion-table
                                 icomplete-with-completion-tables))))
-      (read-buffer prompt (other-buffer (current-buffer))
+      (read-buffer prompt (other-buffer (current-buffer) t)
                    (confirm-nonexistent-file-or-buffer)))))
 
 (defun window-normalize-buffer-to-switch-to (buffer-or-name)
diff --git a/test/lisp/ido-tests.el b/test/lisp/ido-tests.el
index 56ef6cde358..034071b52b3 100644
--- a/test/lisp/ido-tests.el
+++ b/test/lisp/ido-tests.el
@@ -51,4 +51,25 @@ ido-directory-too-big-p
   (let ((ido-big-directories (cons (rx "me/di") ido-big-directories)))
     (should (ido-directory-too-big-p "/some/dir/"))))
 
+(ert-deftest ido-buffer-switch-visible ()
+  "switch-to-buffer should include already visible buffers."
+  (let* ((name "test-buffer-switch-visible")
+         (buffer (get-buffer-create name)))
+    (unwind-protect
+        (progn
+          (switch-to-buffer buffer)
+          (delete-other-windows)
+          (split-window-below)
+          (goto-char (point-min))
+          (other-window 1)
+          (insert "foo")
+          (goto-char (point-max))
+          (cl-letf (((symbol-function 'read-from-minibuffer)
+                     (lambda (&rest args) (nth 5 args))))
+            (call-interactively #'ido-switch-buffer)
+            (call-interactively #'ido-switch-buffer))
+          (should (and (equal name (buffer-name)) (eq (point) (point-max)))))
+      (let (kill-buffer-query-functions)
+        (kill-buffer buffer)))))
+
 ;;; ido-tests.el ends here
diff --git a/test/src/buffer-tests.el b/test/src/buffer-tests.el
index 3c6a9208ffa..b34766c2383 100644
--- a/test/src/buffer-tests.el
+++ b/test/src/buffer-tests.el
@@ -1555,4 +1555,25 @@ test-buffer-chars-modified-ticks
       (if f2 (delete-file f2))
       )))
 
+(ert-deftest test-buffer-switch-visible ()
+  "switch-to-buffer should include already visible buffers."
+  (let* ((name "test-buffer-switch-visible")
+         (buffer (get-buffer-create name)))
+    (unwind-protect
+        (progn
+          (switch-to-buffer buffer)
+          (delete-other-windows)
+          (split-window-below)
+          (goto-char (point-min))
+          (other-window 1)
+          (insert "foo")
+          (goto-char (point-max))
+          (cl-letf (((symbol-function 'read-from-minibuffer)
+                     (lambda (&rest args) (nth 5 args))))
+            (call-interactively #'switch-to-buffer)
+            (call-interactively #'switch-to-buffer))
+          (should (and (equal name (buffer-name)) (eq (point) (point-max)))))
+      (let (kill-buffer-query-functions)
+        (kill-buffer buffer)))))
+
 ;;; buffer-tests.el ends here
-- 
2.36.1

In Commercial Emacs 0.3.1snapshot f0a5a41 in dev (upstream 29.0.50, x86_64-pc-linux-gnu) built on dick
Repository revision: f0a5a41845236f05116b0a8459b5702e4d878b20
Repository branch: dev
Windowing system distributor 'The X.Org Foundation', version 11.0.12013000
System Description: Ubuntu 20.04.4 LTS

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hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
emacs)

Memory information:
((conses 16 1107080 43082)
 (symbols 48 47047 3)
 (strings 32 214940 28162)
 (string-bytes 1 6605441)
 (vectors 16 111778)
 (vector-slots 8 2954688 68976)
 (floats 8 1144 1007)
 (intervals 56 67190 890)
 (buffers 1000 47))