From f7d957c4900620864bb7b5615d22b1becdf47c45 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 25 Mar 2026 22:40:45 +0300
Subject: [PATCH] cgen, checker: fix multiple bugs related to alias + reference
 (fixes #24010)

---
 vlib/v/gen/c/fn.v                             |  6 +++
 ...s_generic_mut_reference_issue_24010_test.v | 44 +++++++++++++++++++
 vlib/v/type_resolver/comptime_resolver.v      |  3 ++
 3 files changed, 53 insertions(+)
 create mode 100644 vlib/v/tests/aliases/alias_generic_mut_reference_issue_24010_test.v

diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 6a132ceb2..ae22ff577 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -2990,6 +2990,12 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type_ ast.Type, lang a
 	exp_sym := g.table.sym(expected_type)
 	mut needs_closing := false
 	old_inside_smartcast := g.inside_smartcast
+	if arg.is_mut && arg.expr.is_auto_deref_var() && arg_typ.is_ptr() && expected_type.is_ptr() {
+		g.arg_no_auto_deref = true
+		g.expr_with_cast(arg.expr, arg_typ, expected_type)
+		g.arg_no_auto_deref = false
+		return
+	}
 	if arg.is_mut && !exp_is_ptr {
 		g.write('&/*mut*/')
 	} else if arg.is_mut && arg_typ.is_ptr() && expected_type.is_ptr()
diff --git a/vlib/v/tests/aliases/alias_generic_mut_reference_issue_24010_test.v b/vlib/v/tests/aliases/alias_generic_mut_reference_issue_24010_test.v
new file mode 100644
index 000000000..d777c25dc
--- /dev/null
+++ b/vlib/v/tests/aliases/alias_generic_mut_reference_issue_24010_test.v
@@ -0,0 +1,44 @@
+pub struct User {
+	name   string
+	age    int
+	height f64
+}
+
+type Users = map[string]User
+
+fn one() {
+	assert typeof[Users]().unaliased_typ == typeof[map[string]User]().idx
+}
+
+fn two[T](mut mutable_val T, val T) {
+	assert mutable_val == val
+	assert T.idx == typeof(val).idx
+	assert typeof(mutable_val).idx == typeof(val).idx
+}
+
+fn three[T, V](mut mutable_val T, val V) {
+	assert mutable_val == val
+	assert T.idx == typeof(val).idx
+	assert V.idx == typeof(val).idx
+	assert typeof(mutable_val).idx == typeof(val).idx
+}
+
+fn decode_map[K, V](mut val map[K]V) {
+	assert typeof(val).idx == typeof[map[string]User]().idx
+}
+
+fn four[T](mut mutable_val T) {
+	$if T.unaliased_typ is $map {
+		decode_map(mut mutable_val)
+	}
+}
+
+fn test_alias_generic_mut_reference_issue_24010() {
+	mut mutable_users := Users(map[string]User{})
+	users := Users(map[string]User{})
+
+	one()
+	two(mut mutable_users, users)
+	three(mut mutable_users, users)
+	four(mut mutable_users)
+}
diff --git a/vlib/v/type_resolver/comptime_resolver.v b/vlib/v/type_resolver/comptime_resolver.v
index f38a67eb2..9e275b455 100644
--- a/vlib/v/type_resolver/comptime_resolver.v
+++ b/vlib/v/type_resolver/comptime_resolver.v
@@ -72,6 +72,9 @@ pub fn (t &ResolverInfo) is_comptime_variant_var(node ast.Ident) bool {
 // typeof_type resolves type for typeof() expr where field.typ is resolved to real type instead of int type to make type(field.typ).name working
 pub fn (mut t TypeResolver) typeof_type(node ast.Expr, default_type ast.Type) ast.Type {
 	if node is ast.Ident {
+		if node.obj is ast.Var && node.obj.is_arg && node.obj.is_auto_deref && node.obj.typ.is_ptr() {
+			return node.obj.typ.deref().clear_flag(.option_mut_param_t)
+		}
 		if t.info.inside_comptime_for && t.info.comptime_for_field_var != '' {
 			if node.obj is ast.Var {
 				obj_typ := node.obj.typ
-- 
2.39.5