patch 8.2.1698: cannot lock a variable in legacy Vim script like in Vim9
Problem: Cannot lock a variable in legacy Vim script like in Vim9.
Solution: Make ":lockvar 0" work.
diff --git a/src/testdir/test_const.vim b/src/testdir/test_const.vim
index 5eb2f69..c88efa6 100644
--- a/src/testdir/test_const.vim
+++ b/src/testdir/test_const.vim
@@ -215,6 +215,14 @@
if 0 | lockvar x | endif
let x = 'again'
+
+ let val = [1, 2, 3]
+ lockvar 0 val
+ let val[0] = 9
+ call assert_equal([9, 2, 3], val)
+ call add(val, 4)
+ call assert_equal([9, 2, 3, 4], val)
+ call assert_fails('let val = [4, 5, 6]', 'E1122:')
endfunc