From 9e351516fea0f3865e4408f7acf93158fd22a38a Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sat, 13 Jun 2026 08:17:00 +0300
Subject: [PATCH] cgen: fix option sumtype if expr struct init (#27443)

---
 vlib/v/gen/c/cgen.v                           |  6 ++-
 ...option_sumtype_if_expr_struct_field_test.v | 47 +++++++++++++++++++
 2 files changed, 51 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/options/option_sumtype_if_expr_struct_field_test.v

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index a3dcebf29..83d7b17ff 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -6576,11 +6576,13 @@ fn (mut g Gen) expr(node_ ast.Expr) {
 				g.expr(g.table.resolve_init(node, g.unwrap_generic(node.typ)))
 			} else {
 				// `user := User{name: 'Bob'}`
+				old_inside_struct_init := g.inside_struct_init
+				old_cur_struct_init_typ := g.cur_struct_init_typ
 				g.inside_struct_init = true
 				g.cur_struct_init_typ = node.typ
 				g.struct_init(node)
-				g.cur_struct_init_typ = 0
-				g.inside_struct_init = false
+				g.cur_struct_init_typ = old_cur_struct_init_typ
+				g.inside_struct_init = old_inside_struct_init
 			}
 		}
 		ast.TypeNode {
diff --git a/vlib/v/tests/options/option_sumtype_if_expr_struct_field_test.v b/vlib/v/tests/options/option_sumtype_if_expr_struct_field_test.v
new file mode 100644
index 000000000..78b1fd34f
--- /dev/null
+++ b/vlib/v/tests/options/option_sumtype_if_expr_struct_field_test.v
@@ -0,0 +1,47 @@
+struct Circle27440 {
+	radius int
+}
+
+struct Square27440 {
+	size int
+}
+
+type Shape27440 = Circle27440 | Square27440
+
+struct Box27440 {
+	shape ?Shape27440
+}
+
+fn new_box27440(use_circle bool, n int) Box27440 {
+	return Box27440{
+		shape: if use_circle {
+			Shape27440(Circle27440{
+				radius: n
+			})
+		} else {
+			Shape27440(Square27440{
+				size: n
+			})
+		}
+	}
+}
+
+fn test_option_sumtype_if_expr_struct_field() {
+	circle_box := new_box27440(true, 4)
+	circle_shape := circle_box.shape or {
+		assert false
+		return
+	}
+
+	assert circle_shape is Circle27440
+	assert circle_shape.radius == 4
+
+	square_box := new_box27440(false, 5)
+	square_shape := square_box.shape or {
+		assert false
+		return
+	}
+
+	assert square_shape is Square27440
+	assert square_shape.size == 5
+}
-- 
2.39.5