impl ReadOnlyFetch for Or, FetchOr, and FetchMutated (#763)

crates/bevy_ecs/hecs/src/query.rs

@@ -263,6 +263,9 @@ macro_rules! impl_or_query {
                 true $( && $T.should_skip(n) )+
             }
         }
+
+        unsafe impl<$( $T: ReadOnlyFetch ),+> ReadOnlyFetch for Or<($( $T ),+)> {}
+        unsafe impl<$( $T: ReadOnlyFetch ),+> ReadOnlyFetch for FetchOr<($( $T ),+)> {}
     };
 }
 
@@ -320,6 +323,7 @@ impl<'a, T: Component> Query for Mutated<'a, T> {
 
 #[doc(hidden)]
 pub struct FetchMutated<T>(NonNull<T>, NonNull<bool>);
+unsafe impl<T> ReadOnlyFetch for FetchMutated<T> {}
 
 impl<'a, T: Component> Fetch<'a> for FetchMutated<T> {
     type Item = Mutated<'a, T>;

crates/bevy_ecs/src/system/into_system.rs

@@ -489,6 +489,43 @@ mod tests {
         assert!(*resources.get::<bool>().unwrap(), "system ran");
     }
 
+    #[test]
+    fn or_query_set_system() {
+        // Regression test for issue #762
+        use crate::{Added, Changed, Mutated, Or};
+        fn query_system(
+            mut ran: ResMut<bool>,
+            set: QuerySet<(
+                Query<Or<(Changed<A>, Changed<B>)>>,
+                Query<Or<(Added<A>, Added<B>)>>,
+                Query<Or<(Mutated<A>, Mutated<B>)>>,
+            )>,
+        ) {
+            let changed = set.q0().iter().count();
+            let added = set.q1().iter().count();
+            let mutated = set.q2().iter().count();
+
+            assert_eq!(changed, 1);
+            assert_eq!(added, 1);
+            assert_eq!(mutated, 0);
+
+            *ran = true;
+        }
+
+        let mut world = World::default();
+        let mut resources = Resources::default();
+        resources.insert(false);
+        world.spawn((A, B));
+
+        let mut schedule = Schedule::default();
+        schedule.add_stage("update");
+        schedule.add_system_to_stage("update", query_system.system());
+
+        schedule.run(&mut world, &mut resources);
+
+        assert!(*resources.get::<bool>().unwrap(), "system ran");
+    }
+
     #[test]
     fn changed_resource_system() {
         fn incr_e_on_flip(_run_on_flip: ChangedRes<bool>, mut i: Mut<i32>) {