patch 8.1.1968: crash when using nested map()
Problem: Crash when using nested map().
Solution: Clear the pointer in prepare_vimvar(). (Ozaki Kiichi,
closes #4890, closes #4891)
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 6984c23..20718bc 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1543,6 +1543,10 @@
let files = readdir('Xdir', {x -> len(add(l, x)) == 2 ? -1 : 1})
call assert_equal(1, len(files))
+ " Nested readdir() must not crash
+ let files = readdir('Xdir', 'readdir("Xdir", "1") != []')
+ call sort(files)->assert_equal(['bar.txt', 'dir', 'foo.txt'])
+
eval 'Xdir'->delete('rf')
endfunc