patch 9.0.0726: looping over list of lists works in script, not in functionv9.0.0726

Problem:    Looping over list of lists and changing the list contents works in
            Vim9 script, not in a compiled function.
Solution:   Mark the loop variable final instead of const. (closes #11347)

1 files changed, 14 insertions, 0 deletions

diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 05fd2fb57f..a0b8352f3f 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -2275,6 +2275,20 @@ def Test_for_loop()
   v9.CheckDefAndScriptSuccess(lines)
 enddef
 
+def Test_for_loop_list_of_lists()
+  # loop variable is final, not const
+  var lines =<< trim END
+      # Filter out all odd numbers in each sublist
+      var list: list<list<number>> = [[1], [1, 2], [1, 2, 3], [1, 2, 3, 4]]
+      for i in list
+          filter(i, (_, n: number): bool => n % 2 == 0)
+      endfor
+
+      assert_equal([[], [2], [2], [2, 4]], list)
+  END
+  v9.CheckDefAndScriptSuccess(lines)
+enddef
+
 def Test_for_loop_with_closure()
   # using the loop variable in a closure results in the last used value
   var lines =<< trim END