From c2a64e2fd76d77383c9a0253b4d4876c790898e4 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Fri, 23 Jan 2026 14:53:18 +0200
Subject: [PATCH] cgen: fix `+=` overloading for aliases, regression after
 29e60da #23967 (fix #26416) (#26423)

---
 vlib/v/gen/c/assign.v                         | 24 +++++++-------
 ...nt_operator_overloading_issue_26416_test.v | 31 +++++++++++++++++++
 2 files changed, 42 insertions(+), 13 deletions(-)
 create mode 100644 vlib/v/tests/aliases/alias_parent_operator_overloading_issue_26416_test.v

diff --git a/vlib/v/gen/c/assign.v b/vlib/v/gen/c/assign.v
index 0ab37c6e7..929a4b358 100644
--- a/vlib/v/gen/c/assign.v
+++ b/vlib/v/gen/c/assign.v
@@ -704,6 +704,7 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 				}
 				pos := g.out.len
 				g.expr(left)
+				struct_info := g.table.final_sym(var_type)
 				if left_sym.info is ast.Struct && left_sym.info.generic_types.len > 0 {
 					concrete_types := left_sym.info.concrete_types
 					mut method_name := left_sym.cname + '_' + util.replace_op(extracted_op)
@@ -725,19 +726,16 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 						g.write(';')
 					}
 					return
-				} else if left_sym.kind == .alias && g.table.final_sym(var_type).kind == .struct {
-					struct_info := g.table.final_sym(var_type)
-					if struct_info.info is ast.Struct && struct_info.info.generic_types.len > 0 {
-						mut method_name := struct_info.cname + '_' + util.replace_op(extracted_op)
-						method_name = g.generic_fn_name(struct_info.info.concrete_types,
-							method_name)
-						g.write(' = ${method_name}(')
-						g.expr(left)
-						g.write(', ')
-						g.expr(val)
-						g.writeln(');')
-						return
-					}
+				} else if left_sym.kind == .alias && struct_info.kind == .struct
+					&& struct_info.info is ast.Struct && struct_info.info.generic_types.len > 0 {
+					mut method_name := struct_info.cname + '_' + util.replace_op(extracted_op)
+					method_name = g.generic_fn_name(struct_info.info.concrete_types, method_name)
+					g.write(' = ${method_name}(')
+					g.expr(left)
+					g.write(', ')
+					g.expr(val)
+					g.writeln(');')
+					return
 				} else {
 					if g.table.final_sym(g.unwrap_generic(var_type)).kind == .array_fixed {
 						g.go_back_to(pos)
diff --git a/vlib/v/tests/aliases/alias_parent_operator_overloading_issue_26416_test.v b/vlib/v/tests/aliases/alias_parent_operator_overloading_issue_26416_test.v
new file mode 100644
index 000000000..f303281e2
--- /dev/null
+++ b/vlib/v/tests/aliases/alias_parent_operator_overloading_issue_26416_test.v
@@ -0,0 +1,31 @@
+pub struct Vec3 {
+pub:
+	x f64
+	y f64
+	z f64
+}
+
+pub fn (u Vec3) + (v Vec3) Vec3 {
+	return Vec3{u.x + v.x, u.y + v.y, u.z + v.z}
+}
+
+pub type Color3 = Vec3
+
+pub fn (u Color3) + (v Color3) Color3 {
+	return Color3{100 + u.x + v.x, 200 + u.y + v.y, 300 + u.z + v.z}
+}
+
+fn color(x int) Color3 {
+	return Color3{1, 2, 3}
+}
+
+fn test_main() {
+	mut c := Color3{1, 2, 3}
+	for _ in 0 .. 3 {
+		c += color(123)
+	}
+	println(c)
+	assert c.x == 304.0 // make sure that the overloaded + for Color3 was called, and NOT the overloaded + for Vec3.
+	assert c.y == 608.0
+	assert c.z == 912.0
+}
-- 
2.39.5