From: Doug Kearns <dougkearns@gmail.com>
Date: Sun, 30 Nov 2025 15:26:22 +0000 (+0000)
Subject: patch 9.1.1942: Vim9: Assignment to read-only registers @: and @% is allowed
X-Git-Tag: v9.1.1942^0
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e5c5378cd27a7a370af7868ec1e4d005b335b2f9;p=thirdparty%2Fvim.git

patch 9.1.1942: Vim9: Assignment to read-only registers @: and @% is allowed

Problem:  Assignment to read-only registers @: and @% is allowed during
          compilation.
Solution: Abort compilation and emit an E354 error when assigning to
          these registers (Doug Kearns).

Fix the E354 error emitted when attempting to declare @: with :var so
that it references the correct register, @:,  rather than the garbage
string "^@".

closes: #18806

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
---

diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index b7b09c9724..a8c6c01cb3 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -1592,12 +1592,17 @@ def Test_assignment_failure()
   v9.CheckDefFailure(['var $VAR = 5'], 'E1016: Cannot declare an environment variable:')
   v9.CheckScriptFailure(['vim9script', 'var $ENV = "xxx"'], 'E1016:')
 
+  # read-only registers
+  v9.CheckDefAndScriptFailure(['var @. = 5'], ['E354:', 'E1066:'], 1)
+  v9.CheckDefAndScriptFailure(['var @. = 5'], ['E354:', 'E1066:'], 1)
+  v9.CheckDefAndScriptFailure(['var @% = 5'], ['E354:', 'E1066:'], 1)
+  v9.CheckDefAndScriptFailure(['var @: = 5'], ['E354:', 'E1066:'], 1)
   if has('dnd')
-    v9.CheckDefFailure(['var @~ = 5'], 'E1066:')
+    v9.CheckDefAndScriptFailure(['var @~ = 5'], ['E354:', 'E1066:'], 1)
   else
-    v9.CheckDefFailure(['var @~ = 5'], 'E354:')
-    v9.CheckDefFailure(['@~ = 5'], 'E354:')
+    v9.CheckDefAndScriptFailure(['var @~ = 5'], ['E354:', 'E1066:'], 1)
   endif
+
   v9.CheckDefFailure(['var @a = 5'], 'E1066:')
   v9.CheckDefFailure(['var @/ = "x"'], 'E1066:')
   v9.CheckScriptFailure(['vim9script', 'var @a = "abc"'], 'E1066:')
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index bbc9e10653..8e5a53d51c 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -3352,7 +3352,11 @@ def Test_expr9_register()
   END
   v9.CheckDefAndScriptSuccess(lines)
 
+  # read-only registers
   v9.CheckDefAndScriptFailure(["@. = 'yes'"], 'E354:', 1)
+  v9.CheckDefAndScriptFailure(["@% = 'yes'"], 'E354:', 1)
+  v9.CheckDefAndScriptFailure(["@: = 'yes'"], 'E354:', 1)
+  v9.CheckDefAndScriptFailure(["@~ = 'yes'"], 'E354:', 1)
 enddef
 
 " This is slow when run under valgrind.
diff --git a/src/version.c b/src/version.c
index a8bff776af..81e8cf3b7a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1942,
 /**/
     1941,
 /**/
diff --git a/src/vim9compile.c b/src/vim9compile.c
index cab48bb8ae..43f8dcb7fa 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1464,7 +1464,9 @@ vim9_declare_error(char_u *name)
     static int
 valid_dest_reg(int name)
 {
-    if ((name == '@' || valid_yank_reg(name, FALSE)) && name != '.')
+    if (name == '@')
+       name = '"';
+    if (name == '/' || name == '=' || valid_yank_reg(name, TRUE))
 	return TRUE;
     emsg_invreg(name);
     return FAIL;