From dbdd16b62560413abcc3c8e893cc3010ccf31666 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sun, 14 Aug 2022 21:46:07 +0100
Subject: [PATCH] patch 9.0.0212: invalid memory access when compiling :unlet

Problem:    Invalid memory access when compiling :unlet.
Solution:   Don't read past the end of the line.
---
 src/testdir/test_vim9_cmd.vim | 11 +++++++++--
 src/version.c                 |  2 ++
 src/vim9cmds.c                |  6 ++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index 79f19f0389a0d..5484ecb7757e5 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -1740,12 +1740,19 @@ def Test_lockvar()
 
   lines =<< trim END
       def _()
-        s:0([], s:0)
         lockv
       enddef
       defcomp
   END
-  v9.CheckScriptFailure(lines, 'E179', 2)
+  v9.CheckScriptFailure(lines, 'E179', 1)
+
+  lines =<< trim END
+      def T()
+        unlet
+      enddef
+      defcomp
+  END
+  v9.CheckScriptFailure(lines, 'E179', 1)
 enddef
 
 def Test_substitute_expr()
diff --git a/src/version.c b/src/version.c
index 3f0bf5151ad21..7de71581568e7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    212,
 /**/
     211,
 /**/
diff --git a/src/vim9cmds.c b/src/vim9cmds.c
index 35a382138bf3b..93032d6bf154e 100644
--- a/src/vim9cmds.c
+++ b/src/vim9cmds.c
@@ -92,6 +92,12 @@ free_locals(cctx_T *cctx)
     int
 check_vim9_unlet(char_u *name)
 {
+    if (*name == NUL)
+    {
+	semsg(_(e_argument_required_for_str), "unlet");
+	return FAIL;
+    }
+
     if (name[1] != ':' || vim_strchr((char_u *)"gwtb", *name) == NULL)
     {
 	// "unlet s:var" is allowed in legacy script.