From eea46c4e1aa9017cb2a225c97422be69d249f92d Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Thu, 7 Apr 2022 17:20:14 +0300
Subject: [PATCH] cgen: fix error, when a struct with over 8 fields, is used as
 a method receiver directly.

---
 vlib/v/gen/c/struct.v                         |  4 +++
 ...ding_on_struct_with_too_many_fields_test.v | 27 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/vlib/v/gen/c/struct.v b/vlib/v/gen/c/struct.v
index a2e85d416c..fa3600c33d 100644
--- a/vlib/v/gen/c/struct.v
+++ b/vlib/v/gen/c/struct.v
@@ -22,6 +22,10 @@ fn (mut g Gen) struct_init(node ast.StructInit) {
 	if is_amp {
 		g.out.go_back(1) // delete the `&` already generated in `prefix_expr()
 	}
+	g.write('(')
+	defer {
+		g.write(')')
+	}
 	if g.is_shared && !g.inside_opt_data && !g.is_arraymap_set {
 		mut shared_typ := node.typ.set_flag(.shared_f)
 		shared_styp = g.typ(shared_typ)
diff --git a/vlib/v/tests/operator_overloading_on_struct_with_too_many_fields_test.v b/vlib/v/tests/operator_overloading_on_struct_with_too_many_fields_test.v
index ed495d287a..ccce689f5a 100644
--- a/vlib/v/tests/operator_overloading_on_struct_with_too_many_fields_test.v
+++ b/vlib/v/tests/operator_overloading_on_struct_with_too_many_fields_test.v
@@ -28,3 +28,30 @@ fn test_op() {
 	dump(a)
 	dump(b)
 }
+
+struct ManyFields {
+mut:
+	f01 int
+	f02 int
+	f03 int
+	f04 int
+	f05 int
+	f06 int
+	f07 int
+	f08 int
+	f09 int
+	f10 int
+	f11 int
+	f12 int
+}
+
+fn (mf ManyFields) inc() ManyFields {
+	mut res := mf
+	res.f01 += 1
+	return res
+}
+
+fn test_a_struct_with_many_fields_can_be_used_as_receiver_directly_without_assigning_to_an_intermediate_variable() {
+	x := ManyFields{}.inc()
+	assert x.f01 == 1
+}