New functions window-state-buffers and tab-bar-get-buffer-tab (bug#38354)

* lisp/window.el (window-state-buffers): New function.
* lisp/tab-bar.el (tab-bar-get-buffer-tab): New function.

* lisp/emacs-lisp/seq.el (seq-some): Add autoload cookie.

* lisp/desktop.el (desktop-buffers-not-to-save-function): New variable.
(desktop-save-buffer-p): Use it.

lisp/desktop.el

@@ -946,7 +946,9 @@ which means to truncate VAR's value to at most MAX-SIZE elements
 	      ")\n"))))
 
 ;; ----------------------------------------------------------------------------
-(defun desktop-save-buffer-p (filename bufname mode &rest _dummy)
+(defvar desktop-buffers-not-to-save-function nil)
+
+(defun desktop-save-buffer-p (filename bufname mode &rest rest)
   "Return t if buffer should have its state saved in the desktop file.
 FILENAME is the visited file name, BUFNAME is the buffer name, and
 MODE is the major mode.
@@ -970,6 +972,9 @@ MODE is the major mode.
 	     (and (null filename)
 		  (null dired-skip)  ; bug#5755
 		  (with-current-buffer bufname desktop-save-buffer)))
+	 (or (null desktop-buffers-not-to-save-function)
+	     (funcall desktop-buffers-not-to-save-function
+		      filename bufname mode rest))
 	 t)))
 
 ;; ----------------------------------------------------------------------------

lisp/emacs-lisp/seq.el

@@ -348,6 +348,7 @@ If SEQUENCE is empty, return INITIAL-VALUE and FUNCTION is not called."
           (throw 'seq--break nil)))
     t))
 
+;;;###autoload
 (cl-defgeneric seq-some (pred sequence)
   "Return non-nil if PRED is satisfied for at least one element of SEQUENCE.
 If so, return the first non-nil value returned by PRED."

lisp/tab-bar.el

@@ -1244,7 +1244,8 @@ in the selected frame."
     (kill-buffer (current-buffer))
     ;; Delete the current window configuration of tab list
     ;; without storing it in the undo list of closed tabs
-    (let (tab-bar-closed-tabs)
+    (let ((tab-bar-mode t) ; avoid message about deleted tab
+          tab-bar-closed-tabs)
       (tab-bar-close-tab nil (1+ (tab-bar--tab-index to-tab))))))
 
 (defun tab-bar-list-mouse-select (event)
@@ -1284,6 +1285,47 @@ indirectly called by the latter."
               (tab-bar-rename-tab name))))
       (tab-bar-new-tab))))
 
+(defun tab-bar-get-buffer-tab (buffer-or-name &optional all-frames)
+  "Return a tab whose window contains BUFFER-OR-NAME, or nil if none.
+BUFFER-OR-NAME may be a buffer or a buffer name and defaults to
+the current buffer.
+
+The optional argument ALL-FRAMES specifies the frames to consider:
+
+- t means consider all tabs on all existing frames.
+
+- `visible' means consider all tabs on all visible frames.
+
+- A frame means consider all tabs on that frame only.
+
+Any other value of ALL-FRAMES means consider all tabs on the
+selected frame and no others."
+  (let ((buffer (if buffer-or-name
+                    (get-buffer buffer-or-name)
+                  (current-buffer))))
+    (when (bufferp buffer)
+      (let ((frames (cond
+                     ((eq all-frames t) (frame-list))
+                     ((eq all-frames 'visible) (visible-frame-list))
+                     ((framep all-frames) (list all-frames))
+                     (t (list (selected-frame))))))
+        (seq-some (lambda (frame)
+                    (with-selected-frame frame
+                      (seq-some (lambda (tab)
+                                  (when (if (eq (car tab) 'current-tab)
+                                            (get-buffer-window buffer frame)
+                                          (let* ((state (cdr (assq 'ws tab)))
+                                                 (buffers (when state
+                                                            (window-state-buffers state))))
+                                            (or
+                                             ;; non-writable window-state
+                                             (memq buffer buffers)
+                                             ;; writable window-state
+                                             (member (buffer-name buffer) buffers))))
+                                    (append tab `((frame . ,frame)))))
+                                (funcall tab-bar-tabs-function))))
+                  frames)))))
+
 
 (defun switch-to-buffer-other-tab (buffer-or-name &optional norecord)
   "Switch to buffer BUFFER-OR-NAME in another tab.

lisp/window.el

@@ -6231,6 +6231,15 @@ windows can get as small as `window-safe-min-height' and
 	    (delete-window window))))
       (window--check frame))))
 
+(defun window-state-buffers (state)
+  "Return all buffers saved to the given window state STATE."
+  (let ((buffer (cadr (assq 'buffer state)))
+        (buffers (mapcan (lambda (item)
+                           (when (memq (car item) '(leaf vc hc))
+                             (window-state-buffers item)))
+                         (if (consp (car state)) (list (cdr state)) (cdr state)))))
+    (if buffer (cons buffer buffers) buffers)))
+
 (defun window-swap-states (&optional window-1 window-2 size)
   "Swap the states of live windows WINDOW-1 and WINDOW-2.
 WINDOW-1 must specify a live window and defaults to the selected