Implement Clone for CombinatorSystem

Where `A, B: Clone`. Needed in order to use chained conditions with
`distributive_run_if`.

crates/bevy_ecs/src/system/combinator.rs

@@ -242,6 +242,18 @@ where
 {
 }
 
+
+impl<Func, A, B> Clone for CombinatorSystem<Func, A, B>
+where
+    A: Clone,
+    B: Clone,
+{
+    /// Clone the combined system. The cloned instance must be `.initialize()`d before it can run.
+    fn clone(&self) -> Self {
+        CombinatorSystem::new(self.a.clone(), self.b.clone(), self.name.clone())
+    }
+}
+
 /// A [`System`] created by piping the output of the first system into the input of the second.
 ///
 /// This can be repeated indefinitely, but system pipes cannot branch: the output is consumed by the receiving system.

crates/bevy_ecs/src/system/mod.rs

@@ -493,12 +493,13 @@ mod tests {
         prelude::AnyOf,
         query::{Added, Changed, Or, With, Without},
         removal_detection::RemovedComponents,
-        schedule::{apply_deferred, IntoSystemConfigs, Schedule},
+        schedule::{apply_deferred, IntoSystemConfigs, Schedule, Condition, common_conditions::resource_exists},
         system::{
             adapter::new, Commands, In, IntoSystem, Local, NonSend, NonSendMut, ParamSet, Query,
             QueryComponentError, Res, ResMut, Resource, System, SystemState,
         },
         world::{FromWorld, World},
+
     };
 
     #[derive(Resource, PartialEq, Debug)]
@@ -1835,4 +1836,26 @@ mod tests {
         assert!(info2.first_flag);
         assert!(!info2.second_flag);
     }
+
+    #[test]
+    fn test_combinator_clone() {
+        let mut world = World::new();
+        #[derive(Resource)]
+        struct A;
+        #[derive(Resource)]
+        struct B;
+        #[derive(Resource, PartialEq, Eq, Debug)]
+        struct C(i32);
+
+        world.insert_resource(A);
+        world.insert_resource(C(0));
+        let mut sched = Schedule::new();
+        sched.add_systems((
+            (|mut res: ResMut<C>| {res.0 += 1;}),
+            (|mut res: ResMut<C>| {res.0 += 2;}),
+        ).distributive_run_if(resource_exists::<A>().or_else(resource_exists::<B>())));
+        sched.initialize(&mut world).unwrap();
+        sched.run(&mut world);
+        assert_eq!(world.get_resource(), Some(&C(3)));
+    }
 }