patch 8.1.1964: crash when using nested map() and filter()v8.1.1964

Problem:    Crash when using nested map() and filter().
Solution:   Do not set the v:key type to string without clearing the pointer.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/testdir/test_filter_map.vim b/src/testdir/test_filter_map.vim
index 1dd3a5b29f..72a8d841e9 100644
--- a/src/testdir/test_filter_map.vim
+++ b/src/testdir/test_filter_map.vim
@@ -53,6 +53,12 @@ func Test_filter_map_list_expr_funcref()
   call assert_equal([0, 2, 4, 6], map([1, 2, 3, 4], function('s:filter4')))
 endfunc
 
+func Test_filter_map_nested()
+  let x = {"x":10}
+  let r = map(range(2), 'filter(copy(x), "1")')
+  call assert_equal([x, x], r)
+endfunc
+
 " dict with funcref
 func Test_filter_map_dict_expr_funcref()
   let dict = {"foo": 1, "bar": 2, "baz": 3}