impl ExclusiveSystemParam for PhantomData

crates/bevy_ecs/src/system/exclusive_system_param.rs

@@ -6,6 +6,7 @@ use crate::{
 };
 use bevy_utils::all_tuples;
 use bevy_utils::synccell::SyncCell;
+use std::marker::PhantomData;
 
 /// A parameter that can be used in an exclusive system (a system with an `&mut World` parameter).
 /// Any parameters implementing this trait must come after the `&mut World` parameter.
@@ -70,6 +71,17 @@ impl<'_s, T: FromWorld + Send + 'static> ExclusiveSystemParam for Local<'_s, T>
     }
 }
 
+impl<S: ?Sized> ExclusiveSystemParam for PhantomData<S> {
+    type State = ();
+    type Item<'s> = PhantomData<S>;
+
+    fn init(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State {}
+
+    fn get_param<'s>(_state: &'s mut Self::State, _system_meta: &SystemMeta) -> Self::Item<'s> {
+        PhantomData
+    }
+}
+
 macro_rules! impl_exclusive_system_param_tuple {
     ($($param: ident),*) => {
         #[allow(unused_variables)]