From bba81ffed6d41823a67f7863131d2e7d100e86ac Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 06:06:51 +0300
Subject: [PATCH] checker: fix wrong alias management in generic methods (fixes
 #24012)

---
 ...ic_mut_method_reference_issue_24012_test.v | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 vlib/v/tests/aliases/alias_generic_mut_method_reference_issue_24012_test.v

diff --git a/vlib/v/tests/aliases/alias_generic_mut_method_reference_issue_24012_test.v b/vlib/v/tests/aliases/alias_generic_mut_method_reference_issue_24012_test.v
new file mode 100644
index 000000000..ded83f8ac
--- /dev/null
+++ b/vlib/v/tests/aliases/alias_generic_mut_method_reference_issue_24012_test.v
@@ -0,0 +1,35 @@
+struct User {
+	name   string
+	age    int
+	height f64
+}
+
+type Users = map[string]User
+
+struct Decoder {}
+
+fn (mut decoder Decoder) decode_map[K, V](mut val map[K]V) ! {
+	_ = decoder
+	assert typeof[K]().idx == typeof[string]().idx
+	assert typeof[V]().idx == typeof[User]().idx
+	assert typeof(val).idx == typeof[map[string]User]().idx
+}
+
+fn decode[T](source string) !T {
+	_ = source
+	mut decoder := Decoder{}
+	mut result := T{}
+	decoder.decode_value(mut result)!
+	return result
+}
+
+fn (mut decoder Decoder) decode_value[T](mut val T) ! {
+	$if T.unaliased_typ is $map {
+		decoder.decode_map(mut val)!
+	}
+}
+
+fn test_alias_generic_mut_method_reference_issue_24012() {
+	_ = decode[Users]('')!
+	_ = decode[map[string]User]('')!
+}
-- 
2.39.5