vim-patch:8.2.2533: Vim9: cannot use a range with :unlet

Problem:    Vim9: cannot use a range with :unlet.
Solution:   Implement ISN_UNLETRANGE.

https://github.com/vim/vim/commit/5b5ae29bd3d7b832b6f15320430f7f191e0abd1f

Co-authored-by: Bram Moolenaar <Bram@vim.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index a392d441cf..9e697d6144 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -1507,6 +1507,21 @@ const char *tv_list_find_str(list_T *const l, const int n)
   return tv_get_string(TV_LIST_ITEM_TV(li));
 }
 
+/// Like tv_list_find() but when a negative index is used that is not found use
+/// zero and set "idx" to zero.  Used for first index of a range.
+listitem_T *tv_list_find_index(list_T *const l, long *const idx)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  listitem_T *li = tv_list_find(l, (int)(*idx));
+  if (li == NULL) {
+    if (*idx < 0) {
+      *idx = 0;
+      li = tv_list_find(l, (int)(*idx));
+    }
+  }
+  return li;
+}
+
 /// Locate item in a list and return its index
 ///
 /// @param[in]  l  List to search.