patch 8.0.0343: b:changedtick can be unlocked
Problem: b:changedtick can be unlocked, even though it has no effect.
(Nikolai Pavlov)
Solution: Add a check and error E940. (closes #1496)
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index bdc4b63..30e7134 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -9082,9 +9082,12 @@
:lockvar v
:let v = 'asdf' " fails!
:unlet v
-< *E741*
+< *E741* *E940*
If you try to change a locked variable you get an
- error message: "E741: Value is locked: {name}"
+ error message: "E741: Value is locked: {name}".
+ If you try to lock or unlock a built-in variable you
+ get an error message: "E940: Cannot lock or unlock
+ variable {name}".
[depth] is relevant when locking a |List| or
|Dictionary|. It specifies how deep the locking goes: