bug#69993: Wrap window buffers while cycling

[Juri Linkov <juri@linkov.net>]

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>>> I think the following is problematic:
>>>
>>>    (defun tab-line-switch-to-prev-tab (&optional event)
>>>      "Switch to the previous tab's buffer.
>>>    Its effect is the same as using the `previous-buffer' command
>>>    (\\[previous-buffer])."
>>>
>>> If the "previous tab" does not show the buffer 'switch-to-prev-buffer'
>>> would switch to, then the doc is wrong.  I'm not sure whether
>>> 'tab-line-tabs-window-buffers' can guarantee that this chooses the same
>>> buffer 'switch-to-prev-buffer' would switch to, though.  If it doesn't,
>>> then the effect should be that of C-x b switching to a buffer earlier
>>> shown in that window.  BTW, burying a buffer removes it from the tab
>>> line but does not prevent 'switch-to-prev-buffer' from switching to it -
>>> it just makes it very unlikely IIRC.
>>
>> tab-line-switch-to-prev-tab doesn't choose buffers itself:
>> for tab-line-tabs-window-buffers it just delegates the task
>> to switch-to-prev-buffer.
>
> But what is the "previous tab"?  IIUC it is the one on the left of the
> current tab in the tab line.  But that tab is not necessarily the one
> 'switch-to-prev-buffer' will switch to.

It's the same tab buffer that 'switch-to-prev-buffer' will switch to,
while using tab-line-tabs-window-buffers that is the default behavior.

So here are changes in the documentation that explain this:


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diff --git a/lisp/tab-line.el b/lisp/tab-line.el
index cc60f94c9c5..12414f0e06f 100644
--- a/lisp/tab-line.el
+++ b/lisp/tab-line.el
@@ -835,31 +849,48 @@
         (switch-to-buffer buffer))))))
 
 (defcustom tab-line-switch-cycling nil
-  "Enable cycling tab switch.
+  "Wrap tabs on tab switch while cycling.
 If non-nil, `tab-line-switch-to-prev-tab' in the first tab
 switches to the last tab and `tab-line-switch-to-next-tab' in the
-last tab switches to the first tab.  This variable is not consulted
-when `tab-line-tabs-function' is `tab-line-tabs-window-buffers'."
+last tab switches to the first tab.
+
+When `tab-line-tabs-function' is `tab-line-tabs-window-buffers',
+then you can customize `switch-to-prev-buffer-wrap' to t
+to achieve the same wrapping effect."
   :type 'boolean
   :group 'tab-line
   :version "28.1")
 
 (defun tab-line-switch-to-prev-tab (&optional event)
   "Switch to the previous tab's buffer.
-Its effect is the same as using the `previous-buffer' command
-(\\[previous-buffer])."
+When `tab-line-tabs-function' is `tab-line-tabs-window-buffers',
+its effect is the same as using the `previous-buffer' command
+\(\\[previous-buffer]).  To wrap buffer cycling in this case,
+you can customize `switch-to-prev-buffer-wrap'.
+
+For other values of `tab-line-tabs-function' this command
+switches to the previous buffer in the sequence defined by
+`tab-line-tabs-function'.  To wrap buffer cycling in this case,
+you can customize `tab-line-switch-cycling'."
   (interactive (list last-nonmenu-event))
   (let ((window (and (listp event) (posn-window (event-start event)))))
     (if (eq tab-line-tabs-function #'tab-line-tabs-window-buffers)
@@ -835,31 +849,48 @@
 
 (defun tab-line-switch-to-next-tab (&optional event)
   "Switch to the next tab's buffer.
-Its effect is the same as using the `next-buffer' command
-(\\[next-buffer])."
+When `tab-line-tabs-function' is `tab-line-tabs-window-buffers',
+its effect is the same as using the `next-buffer' command
+\(\\[next-buffer]).  To wrap buffer cycling in this case,
+you can customize `switch-to-prev-buffer-wrap'.
+
+For other values of `tab-line-tabs-function' this command
+switches to the next buffer in the sequence defined by
+`tab-line-tabs-function'.  To wrap buffer cycling in this case,
+you can customize `tab-line-switch-cycling'."
   (interactive (list last-nonmenu-event))
   (let ((window (and (listp event) (posn-window (event-start event)))))
     (if (eq tab-line-tabs-function #'tab-line-tabs-window-buffers)
         (switch-to-next-buffer window)
       (with-selected-window (or window (selected-window))