Fix undo boundary in recursive edit (Bug#23632)

[gnu-emacs] / lisp / simple.el

diff --git a/lisp/simple.el b/lisp/simple.el
index 24d2d7fbc0f902d4e76c66a83061044c3e04e38f..e38bf70f520cd3262d559ff2ded0adff0bec148c 100644 (file)
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1418,10 +1418,11 @@ If nil, don't change the value of `debug-on-error'."
   :version "21.1")
 
 (defun eval-expression-print-format (value)
-  "Format VALUE as a result of evaluated expression.
-Return a formatted string which is displayed in the echo area
-in addition to the value printed by prin1 in functions which
-display the result of expression evaluation."
+  "If VALUE in an integer, return a specially formatted string.
+This string will typically look like \" (#o1, #x1, ?\\C-a)\".
+If VALUE is not an integer, nil is returned.
+This function is used by functions like `prin1' that display the
+result of expression evaluation."
   (if (and (integerp value)
           (or (eq standard-output t)
               (zerop (prefix-numeric-value current-prefix-arg))))
@@ -2838,6 +2839,18 @@ buffers that were changed during the last command.")
 
 If set to non-nil, this will effectively disable the timer.")
 
+(defvar-local undo-auto-disable-boundaries nil
+  "Disable the automatic addition of boundaries.
+
+If set to non-nil, `undo-boundary' will not be called
+automatically in a buffer either at the end of a command, or as a
+result of `undo-auto-current-boundary-timer'.
+
+When this is set to non-nil, it is important to ensure that
+`undo-boundary' is called frequently enough. Failure to do so
+will result in user-visible warnings that the situation is
+probably a bug.")
+
 (defvar undo-auto--this-command-amalgamating nil
   "Non-nil if `this-command' should be amalgamated.
 This variable is set to nil by `undo-auto--boundaries' and is set
@@ -2877,7 +2890,8 @@ REASON describes the reason that the boundary is being added; see
   (dolist (b undo-auto--undoably-changed-buffers)
           (when (buffer-live-p b)
             (with-current-buffer b
-              (undo-auto--ensure-boundary cause))))
+              (unless undo-auto-disable-boundaries
+                (undo-auto--ensure-boundary cause)))))
   (setq undo-auto--undoably-changed-buffers nil))
 
 (defun undo-auto--boundary-timer ()
@@ -2896,18 +2910,16 @@ REASON describes the reason that the boundary is being added; see
 
 This list is maintained by `undo-auto--undoable-change' and
 `undo-auto--boundaries' and can be affected by changes to their
-default values.
-
-See also `undo-auto--buffer-undoably-changed'.")
+default values.")
 
 (defun undo-auto--add-boundary ()
   "Add an `undo-boundary' in appropriate buffers."
   (undo-auto--boundaries
    (let ((amal undo-auto--this-command-amalgamating))
-       (setq undo-auto--this-command-amalgamating nil)
-       (if amal
-           'amalgamate
-         'command))))
+     (setq undo-auto--this-command-amalgamating nil)
+     (if amal
+         'amalgamate
+       'command))))
 
 (defun undo-auto-amalgamate ()
   "Amalgamate undo if necessary.