patch 8.2.3682: Vim9: assigning to a script variable drops the type Commit: https://github.com/vim/vim/commit/7824fc80f675b8098e6483ce082e287aad14b6da Author: Bram Moolenaar <Bram@vim.org> Date: Fri Nov 26 17:36:51 2021 +0000 patch 8.2.3682: Vim9: assigning to a script variable drops the type Problem: Vim9: assigning to a script variable drops the required type. Solution: Lookup the type of the variable and use it. (closes https://github.com/vim/vim/issues/9219)

--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -322,6 +322,16 @@ def Test_skipped_assignment()
   CheckDefAndScriptSuccess(lines)
 enddef
 
+def Test_assign_keep_type()
+  var lines =<< trim END
+      vim9script
+      var l: list<number> = [123]
+      l = [123]
+      l->add('string')
+  END
+  CheckScriptFailure(lines, 'E1012:', 4)
+enddef
+
 def Test_assign_unpack()
   var lines =<< trim END
     var v1: number