# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1643975103 -3600
# Node ID e2bb282376956eac2daac513007c6d01a0770b06
# Parent  77f6bef22e2594d04204648a0c8b4232c089879c
patch 8.2.4295: Vim9: concatenating two lists may result in wrong type

Commit: https://github.com/vim/vim/commit/46950b225fab2e10245a04952b2c238e0362e1b7
Author: Bram Moolenaar <Bram@vim.org>
Date:   Fri Feb 4 11:36:51 2022 +0000

    patch 8.2.4295: Vim9: concatenating two lists may result in wrong type

    Problem:    Vim9: concatenating two lists may result in wrong type.
    Solution:   Remove the type instead of using list<any>. (closes https://github.com/vim/vim/issues/9692)

diff --git a/src/list.c b/src/list.c
--- a/src/list.c
+++ b/src/list.c
@@ -1216,11 +1216,10 @@ list_copy(list_T *orig, int deep, int to
     copy = list_alloc();
     if (copy != NULL)
     {
-	if (orig->lv_type == NULL)
+	if (orig->lv_type == NULL || top || deep)
 	    copy->lv_type = NULL;
 	else
-	    copy->lv_type = alloc_type(top || deep
-						 ? &t_list_any: orig->lv_type);
+	    copy->lv_type = alloc_type(orig->lv_type);
 	if (copyID != 0)
 	{
 	    // Do this before adding the items, because one of the items may
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1500,6 +1500,12 @@ def Test_expr5_list_add()
       assert_equal([[1, 2]], lln)
   END
   v9.CheckDefAndScriptSuccess(lines)
+
+  lines =<< trim END
+      var ln: list<number> = [0]
+      var lln: list<list<number>> = [ln + []]
+  END
+  v9.CheckDefAndScriptSuccess(lines)
 enddef
 
 " test multiply, divide, modulo
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4295,
+/**/
     4294,
 /**/
     4293,