From f7e99809e0fb2cef2124c27ee45a028d87d2af09 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 26 Feb 2026 11:31:32 +0300
Subject: [PATCH] checker: fix local variable with module before should give a
 compiler error (fixes #10658)

---
 vlib/v/checker/tests/module_selector_decl_assign_err.out | 7 +++++++
 vlib/v/checker/tests/module_selector_decl_assign_err.vv  | 6 ++++++
 vlib/v/parser/assign.v                                   | 4 ++++
 3 files changed, 17 insertions(+)
 create mode 100644 vlib/v/checker/tests/module_selector_decl_assign_err.out
 create mode 100644 vlib/v/checker/tests/module_selector_decl_assign_err.vv

diff --git a/vlib/v/checker/tests/module_selector_decl_assign_err.out b/vlib/v/checker/tests/module_selector_decl_assign_err.out
new file mode 100644
index 000000000..e306285b3
--- /dev/null
+++ b/vlib/v/checker/tests/module_selector_decl_assign_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/module_selector_decl_assign_err.vv:4:5: error: non-name `os.args` on left side of `:=`
+    2 | 
+    3 | fn main() {
+    4 |     os.args := []string{}
+      |        ~~~~
+    5 |     println(os.args)
+    6 | }
diff --git a/vlib/v/checker/tests/module_selector_decl_assign_err.vv b/vlib/v/checker/tests/module_selector_decl_assign_err.vv
new file mode 100644
index 000000000..01a158a5e
--- /dev/null
+++ b/vlib/v/checker/tests/module_selector_decl_assign_err.vv
@@ -0,0 +1,6 @@
+import os
+
+fn main() {
+	os.args := []string{}
+	println(os.args)
+}
diff --git a/vlib/v/parser/assign.v b/vlib/v/parser/assign.v
index ae927e0bb..3e4e94b24 100644
--- a/vlib/v/parser/assign.v
+++ b/vlib/v/parser/assign.v
@@ -204,6 +204,10 @@ fn (mut p Parser) partial_assign_stmt(left []ast.Expr) ast.Stmt {
 		match mut lx {
 			ast.Ident {
 				if op == .decl_assign {
+					if lx.name.contains('.') {
+						return p.error_with_pos('non-name `${lx.name}` on left side of `:=`',
+							lx.pos)
+					}
 					if p.scope.known_var(lx.name) {
 						if !(p.pref.translated_go && lx.name in ['err', 'ok']) {
 							return p.error_with_pos('redefinition of `${lx.name}`', lx.pos)
-- 
2.39.5