bug#52237: 29.0.50; [PATCH] Doubled separators in context-menu-mode

[Jim Porter <jporterbugs@gmail.com>]

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Sometimes, menu separators are doubled up in context-menu-mode. To see 
this in action:

   emacs -Q --eval '(context-menu-mode)'
   ;; Right-click somewhere in the scratch buffer, like the empty area.

You should see a double separator just before "Lisp-Interaction". 
`context-menu-map' tries to eliminate doubled separators, but it doesn't 
account for *tripled* separators. If we have a menu like so ("->" is the 
current list item when iterating):

-> (separator-foo "--")
    (separator-bar "--")
    (separator-baz "--")
    (regular-item "Item")

The duplicate remover sees that both the current item and the next are 
separators, so removes it:

-> (separator-foo "--")
    (separator-baz "--")
    (regular-item "Item")

But then the very next operation is to move to the next list item:

    (separator-foo "--")
-> (separator-baz "--")
    (regular-item "Item")

Now, on the next iteration of the while loop, it won't detect the 
duplicate because it's too far ahead. Attached is a patch to fix this; 
it only advances to the next list item when it *didn't* just delete a 
duplicate separator. That way, it can keep deleting subsequent dupes 
until it sees a non-separator item.

I've only tested this on Emacs 29 so far, but it may occur on Emacs 28 
as well. Also, I noticed that separators can appear at the beginning 
and/or end of the context menu. Should they be removed too?

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From b5983b920eba32fa944758f510cb5fee6c281d4b Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Wed, 1 Dec 2021 21:55:31 -0800
Subject: [PATCH] Ensure there are no duplicate separators when creating a
 context menu

Previously, if there were three or more consecutive menu separators,
not all of them would be removed.

* lisp/mouse.el (context-menu-map): Ensure no duplicate separators.
---
 lisp/mouse.el | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lisp/mouse.el b/lisp/mouse.el
index 3ab9fbcdfe..ec43aecdd0 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -330,10 +330,10 @@ context-menu-map
     ;; Remove duplicate separators
     (let ((l menu))
       (while (consp l)
-        (when (and (equal (cdr-safe (car l)) menu-bar-separator)
-                   (equal (cdr-safe (cadr l)) menu-bar-separator))
-          (setcdr l (cddr l)))
-        (setq l (cdr l))))
+        (if (and (equal (cdr-safe (car l)) menu-bar-separator)
+                 (equal (cdr-safe (cadr l)) menu-bar-separator))
+            (setcdr l (cddr l))
+          (setq l (cdr l)))))
 
     (when (functionp context-menu-filter-function)
       (setq menu (funcall context-menu-filter-function menu click)))
-- 
2.25.1