patch 8.1.1554: docs and tests for :const can be improved
Problem: Docs and tests for :const can be improved.
Solution: Improve documentation, add a few more tests. (Ryuichi Hayashida,
closes #4551)
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 83a8995..549d27b 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -11619,10 +11619,9 @@
If the system does not support deleting an environment
variable, it is made empty.
- *:cons* *:const* *E996*
+ *:cons* *:const*
:cons[t] {var-name} = {expr1}
:cons[t] [{name1}, {name2}, ...] = {expr1}
-:cons[t] [{name1}, {name2}, ...] .= {expr1}
:cons[t] [{name}, ..., ; {lastname}] = {expr1}
:cons[t] {var-name} =<< [trim] {marker}
text...
@@ -11641,7 +11640,11 @@
|:const| does not allow to for changing a variable. >
:let x = 1
:const x = 2 " Error!
-<
+< *E996*
+ Note that environment variables, option values and
+ register values cannot be used here, since they cannot
+ be locked.
+
:lockv[ar][!] [depth] {name} ... *:lockvar* *:lockv*
Lock the internal variable {name}. Locking means that
it can no longer be changed (until it is unlocked).