From 65259b5c6a8ad4edaf6eeb8dbb7b50342c64d403 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Tue, 23 Nov 2021 14:52:06 +0000
Subject: [PATCH] patch 8.2.3656: Vim9: no error for an evironment variable by
 itself

Problem:    Vim9: no error for an evironment variable by itself.
Solution:   Give a "without effect" error. (closes #9166)
---
 src/ex_eval.c                 | 5 ++++-
 src/testdir/test_vim9_cmd.vim | 7 +++++++
 src/version.c                 | 2 ++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/ex_eval.c b/src/ex_eval.c
index 4e38e9649..b3c38a1ea 100644
--- a/src/ex_eval.c
+++ b/src/ex_eval.c
@@ -888,7 +888,8 @@ report_discard_pending(int pending, void *value)
 }
 
 /*
- * Return TRUE if "arg" is only a variable, register or option name.
+ * Return TRUE if "arg" is only a variable, register, environment variable or
+ * option name.
  */
     int
 cmd_is_name_only(char_u *arg)
@@ -911,6 +912,8 @@ cmd_is_name_only(char_u *arg)
 	    if (STRNCMP("l:", p, 2) == 0 || STRNCMP("g:", p, 2) == 0)
 		p += 2;
 	}
+	else if (*p == '$')
+	    ++p;
 	get_name_len(&p, &alias, FALSE, FALSE);
     }
     name_only = ends_excmd2(arg, skipwhite(p));
diff --git a/src/testdir/test_vim9_cmd.vim b/src/testdir/test_vim9_cmd.vim
index 16f5d55d0..81899d6f0 100644
--- a/src/testdir/test_vim9_cmd.vim
+++ b/src/testdir/test_vim9_cmd.vim
@@ -584,6 +584,13 @@ def Test_use_register()
   END
   CheckDefAndScriptFailure(lines, 'E1207:', 2)
   &g:showbreak = ''
+
+  lines =<< trim END
+      $SomeEnv = 'value'
+      $SomeEnv
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+  $SomeEnv = ''
 enddef
 
 def Test_environment_use_linebreak()
diff --git a/src/version.c b/src/version.c
index ea776459e..e47963041 100644
--- a/src/version.c
+++ b/src/version.c
@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3656,
 /**/
     3655,
 /**/
-- 
2.50.1