From 856b923cc9ec4c0628f094eae6fd735ab5c5a669 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Tue, 14 Apr 2026 12:45:35 +0300
Subject: [PATCH] checker: comparing interface with struct instance gives c
 error: invalid operand types for binary operation, invalid aggregate type for
 register load (fixes #24018)

---
 .../tests/interface_struct_comparison_err.out | 14 ++++++++
 .../tests/interface_struct_comparison_err.vv  | 36 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 vlib/v/checker/tests/interface_struct_comparison_err.out
 create mode 100644 vlib/v/checker/tests/interface_struct_comparison_err.vv

diff --git a/vlib/v/checker/tests/interface_struct_comparison_err.out b/vlib/v/checker/tests/interface_struct_comparison_err.out
new file mode 100644
index 000000000..7042f48ba
--- /dev/null
+++ b/vlib/v/checker/tests/interface_struct_comparison_err.out
@@ -0,0 +1,14 @@
+vlib/v/checker/tests/interface_struct_comparison_err.vv:22:30: error: `?IGameObject` cannot be used as `GameObject`, unwrap the option first
+   20 | fn (mut gameobject GameObject) collision(mut o IGameObject) {
+   21 |     _ = o
+   22 |     if gameobject != gameobject.owner {
+      |                                 ~~~~~
+   23 |         eprintln('Collision')
+   24 |     }
+vlib/v/checker/tests/interface_struct_comparison_err.vv:22:5: error: infix expr: cannot use `IGameObject` (right expression) as `GameObject`
+   20 | fn (mut gameobject GameObject) collision(mut o IGameObject) {
+   21 |     _ = o
+   22 |     if gameobject != gameobject.owner {
+      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   23 |         eprintln('Collision')
+   24 |     }
diff --git a/vlib/v/checker/tests/interface_struct_comparison_err.vv b/vlib/v/checker/tests/interface_struct_comparison_err.vv
new file mode 100644
index 000000000..0af88af13
--- /dev/null
+++ b/vlib/v/checker/tests/interface_struct_comparison_err.vv
@@ -0,0 +1,36 @@
+module main
+
+@[heap]
+interface IGameObject {
+mut:
+	name  string
+	speed f32
+	owner ?&IGameObject
+	collision(mut o IGameObject)
+}
+
+@[heap]
+struct GameObject implements IGameObject {
+mut:
+	name  string
+	speed f32
+	owner ?&IGameObject
+}
+
+fn (mut gameobject GameObject) collision(mut o IGameObject) {
+	_ = o
+	if gameobject != gameobject.owner {
+		eprintln('Collision')
+	}
+}
+
+fn main() {
+	mut ship := &GameObject{
+		name: 'ship'
+	}
+	mut rocket := &GameObject{
+		name:  'rocket'
+		owner: ship
+	}
+	rocket.collision(mut ship)
+}
-- 
2.39.5