[nongnu] elpa/undo-fu 1d60424680 50/82: Raise error when using undo-fu commands when undo has been disabled

[ELPA Syncer]

branch: elpa/undo-fu
commit 1d60424680a2eff6a20f0d462057b2fc1bc7f5f6
Author: Campbell Barton <ideasman42@gmail.com>
Commit: Campbell Barton <ideasman42@gmail.com>

    Raise error when using undo-fu commands when undo has been disabled
    
    While in this case nothing useful can be done,
    raise an error since this was failing to set the checkpoint
    with an unhelpful error.
---
 changelog.rst | 5 +++++
 undo-fu.el    | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/changelog.rst b/changelog.rst
index 08913245fe..0bd9d09ece 100644
--- a/changelog.rst
+++ b/changelog.rst
@@ -3,6 +3,11 @@
 Change Log
 ##########
 
+- In development
+
+  - Raise an error when using undo commands when undo has been disabled for 
the buffer.
+    *(was failing to set the checkpoint in this case).*
+
 - Version 0.3 (2020-03-03)
 
   - Support non-destructive commands between undo/redo actions without 
breaking the chain.
diff --git a/undo-fu.el b/undo-fu.el
index 283f529bfb..eba23d64ed 100644
--- a/undo-fu.el
+++ b/undo-fu.el
@@ -111,6 +111,11 @@ Optional argument BODY runs with the message suffix."
             (apply ,message-orig (append (list (concat arg "%s")) args (list 
,suffix))))))
       ,@body)))
 
+(defun undo-fu--undo-enabled-or-error ()
+  "Raise a user error when undo is disabled."
+  (when (eq t buffer-undo-list)
+    (user-error "Undo has been disabled!")))
+
 (defun undo-fu--next-step (list)
   "Get the next undo step in the list.
 
@@ -196,6 +201,8 @@ wraps the `undo' function.
 
 Optional argument ARG The number of steps to redo."
   (interactive "*p")
+  ;; Raise error since we can't do anything useful in this case.
+  (undo-fu--undo-enabled-or-error)
 
   (let*
     ( ;; Assign for convenience.
@@ -329,6 +336,8 @@ wraps the `undo-only' function.
 
 Optional argument ARG the number of steps to undo."
   (interactive "*p")
+  ;; Raise error since we can't do anything useful in this case.
+  (undo-fu--undo-enabled-or-error)
 
   (let*
     ( ;; Assign for convenience.