commit d25ec2cfa0c25c3b00b7f8963b8aea799df1f20a
author Bram Moolenaar <Bram@vim.org> Mon Mar 30 21:05:45 2020 +0200
committer Bram Moolenaar <Bram@vim.org> Mon Mar 30 21:05:45 2020 +0200
tree e3cfefe979dd73574dec6f8edc5388b6afba0a5e
parent ca68ae13114619df3e4c195b41ad0575516f5ff6

patch 8.2.0483: Vim9: "let x = x + 1" does not give an error

Problem:    Vim9: "let x = x + 1" does not give an error.
Solution:   Hide the variable when compiling the expression.

src/testdir/test_vim9_expr.vim

diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index f61ff53..770890e 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -738,6 +738,8 @@
   call CheckDefFailure("let x = {'a': xxx}", 'E1001:')
   call CheckDefFailure("let x = {xxx: 8}", 'E1001:')
   call CheckDefFailure("let x = #{a: 1, a: 2}", 'E721:')
+  call CheckDefFailure("let x += 1", 'E1020:')
+  call CheckDefFailure("let x = x + 1", 'E1001:')
   call CheckDefExecFailure("let x = g:anint.member", 'E715:')
   call CheckDefExecFailure("let x = g:dict_empty.member", 'E716:')
 enddef