Guard against VisibilityClass being duplicated while cloning

crates/bevy_camera/src/visibility/mod.rs

@@ -150,11 +150,16 @@ impl InheritedVisibility {
 /// When adding a new renderable component, you'll typically want to write an
 /// add-component hook that adds the type ID of that component to the
 /// [`VisibilityClass`] array. See `custom_phase_item` for an example.
+///
+/// `VisibilityClass` is automatically added by a hook on the `Mesh3d` and
+/// `Mesh2d` components. To avoid duplicating the `VisibilityClass` and
+/// causing issues when cloning, we use `#[component(clone_behavior=Ignore)]`
 //
 // Note: This can't be a `ComponentId` because the visibility classes are copied
 // into the render world, and component IDs are per-world.
 #[derive(Clone, Component, Default, Reflect, Deref, DerefMut)]
 #[reflect(Component, Default, Clone)]
+#[component(clone_behavior=Ignore)]
 pub struct VisibilityClass(pub SmallVec<[TypeId; 1]>);
 
 /// Algorithmically-computed indication of whether an entity is visible and should be extracted for rendering.
@@ -988,4 +993,27 @@ mod test {
         assert_eq!(1, size_of::<Visibility>());
         assert_eq!(1, size_of::<Option<Visibility>>());
     }
+
+    #[derive(Component, Default, Clone, Reflect)]
+    #[require(VisibilityClass)]
+    #[reflect(Component, Default, Clone)]
+    #[component(on_add = add_visibility_class::<Self>)]
+    struct TestVisibilityClassHook;
+
+    #[test]
+    fn test_add_visibility_class_hook() {
+        let mut world = World::new();
+        let entity = world.spawn(TestVisibilityClassHook).id();
+        let entity_clone = world.spawn_empty().id();
+        world
+            .entity_mut(entity)
+            .clone_with_opt_out(entity_clone, |_| {});
+
+        let entity_visibility_class = world.entity(entity).get::<VisibilityClass>().unwrap();
+        assert_eq!(entity_visibility_class.len(), 1);
+
+        let entity_clone_visibility_class =
+            world.entity(entity_clone).get::<VisibilityClass>().unwrap();
+        assert_eq!(entity_clone_visibility_class.len(), 1);
+    }
 }