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bug#34405: 26.1; patch for cancel-change-group to work after undo
From: |
Braun Gábor |
Subject: |
bug#34405: 26.1; patch for cancel-change-group to work after undo |
Date: |
Tue, 12 Nov 2019 18:05:48 +0100 |
Hi,
Please consider the following fix to the problem, patching function
cancel-change-group.
In the original implementation, the only form depending on whether the
last command was an undo is the line
(unless (eq last-command 'undo) (undo-start))
which sets pending-undo-list to buffer-undo-list, when the last command
was not an undo. When it was, then pending-undo-list probably contains
the pending undo entries from a buffer state before the start of the
change group, which are obviously irrelevant for cancelling the change
group.
The fix below is to use buffer-undo-list instead of pending-undo-list,
essentially inlining the call to undo-more for this change.
As a side effect, the value of pending-undo-list will no longer be
changed by cancel-change-group (unless something in the undo log changes
it), but as far as I see, it doesn't matter, as its value is useful only
directly after an undo command.
--- lisp/subr.el
+++ lisp/subr.el
@@ -2669,14 +2669,17 @@
(progn
;; Temporarily truncate the undo log at ELT.
(when (consp elt)
- (setcar elt nil) (setcdr elt nil))
- (unless (eq last-command 'undo) (undo-start))
- ;; Make sure there's no confusion.
- (when (and (consp elt) (not (eq elt (last pending-undo-
list))))
- (error "Undoing to some unrelated state"))
+ (setcar elt nil) (setcdr elt nil)
+ ;; Make sure there's no confusion.
+ (unless (eq elt (last buffer-undo-list))
+ (error "Undoing to some unrelated state")))
;; Undo it all.
(save-excursion
- (while (listp pending-undo-list) (undo-more 1)))
+ (let ((undo-in-progress t))
+ (while buffer-undo-list
+ ;; Undo one step, removing it from undo log.
+ (setq buffer-undo-list
+ (primitive-undo 1 buffer-undo-list)))))
;; Revert the undo info to what it was when we grabbed
;; the state.
(setq buffer-undo-list elt))
Best wishes,
Gábor
- bug#34405: 26.1; patch for cancel-change-group to work after undo,
Braun Gábor <=