Fix access checks for DeferredWorld as SystemParam.

crates/bevy_ecs/src/query/access.rs

@@ -309,6 +309,16 @@ impl<T: SparseSetIndex> Access<T> {
         self.writes_all_resources || !self.resource_writes.is_clear()
     }
 
+    /// Returns `true` if this accesses any resources or components.
+    pub fn has_any_read(&self) -> bool {
+        self.has_any_component_read() || self.has_any_resource_read()
+    }
+
+    /// Returns `true` if this accesses any resources or components mutably.
+    pub fn has_any_write(&self) -> bool {
+        self.has_any_component_write() || self.has_any_resource_write()
+    }
+
     /// Returns true if this has an archetypal (indirect) access to the component given by `index`.
     ///
     /// This is a component whose value is not accessed (and thus will never cause conflicts),
@@ -1319,12 +1329,16 @@ impl<T: SparseSetIndex> FilteredAccessSet<T> {
 
     /// Marks the set as reading all possible indices of type T.
     pub fn read_all(&mut self) {
-        self.combined_access.read_all();
+        let mut filter = FilteredAccess::matches_everything();
+        filter.read_all();
+        self.add(filter);
     }
 
     /// Marks the set as writing all T.
     pub fn write_all(&mut self) {
-        self.combined_access.write_all();
+        let mut filter = FilteredAccess::matches_everything();
+        filter.write_all();
+        self.add(filter);
     }
 
     /// Removes all accesses stored in this set.

crates/bevy_ecs/src/system/mod.rs

@@ -349,7 +349,7 @@ mod tests {
             Commands, In, IntoSystem, Local, NonSend, NonSendMut, ParamSet, Query, Res, ResMut,
             Single, StaticSystemParam, System, SystemState,
         },
-        world::{EntityMut, FromWorld, World},
+        world::{DeferredWorld, EntityMut, FromWorld, World},
     };
 
     #[derive(Resource, PartialEq, Debug)]
@@ -1624,6 +1624,36 @@ mod tests {
         super::assert_system_does_not_conflict(system);
     }
 
+    #[test]
+    #[should_panic(
+        expected = "error[B0001]: Query<EntityRef, ()> in system bevy_ecs::system::tests::assert_deferred_world_and_entity_ref_system_does_conflict_first::system accesses component(s) in a way that conflicts with a previous system parameter. Consider using `Without<T>` to create disjoint Queries or merging conflicting Queries into a `ParamSet`. See: https://bevyengine.org/learn/errors/b0001"
+    )]
+    fn assert_deferred_world_and_entity_ref_system_does_conflict_first() {
+        fn system(_world: DeferredWorld, _query: Query<EntityRef>) {}
+        super::assert_system_does_not_conflict(system);
+    }
+
+    #[test]
+    #[should_panic(
+        expected = "DeferredWorld in system bevy_ecs::system::tests::assert_deferred_world_and_entity_ref_system_does_conflict_second::system conflicts with a previous access."
+    )]
+    fn assert_deferred_world_and_entity_ref_system_does_conflict_second() {
+        fn system(_query: Query<EntityRef>, _world: DeferredWorld) {}
+        super::assert_system_does_not_conflict(system);
+    }
+
+    #[test]
+    fn assert_deferred_world_and_empty_query_does_not_conflict_first() {
+        fn system(_world: DeferredWorld, _query: Query<Entity>) {}
+        super::assert_system_does_not_conflict(system);
+    }
+
+    #[test]
+    fn assert_deferred_world_and_empty_query_does_not_conflict_second() {
+        fn system(_query: Query<Entity>, _world: DeferredWorld) {}
+        super::assert_system_does_not_conflict(system);
+    }
+
     #[test]
     #[should_panic]
     fn panic_inside_system() {

crates/bevy_ecs/src/system/system_param.rs

@@ -1072,9 +1072,16 @@ unsafe impl<'w> SystemParam for DeferredWorld<'w> {
     type Item<'world, 'state> = DeferredWorld<'world>;
 
     fn init_state(_world: &mut World, system_meta: &mut SystemMeta) -> Self::State {
-        system_meta.component_access_set.read_all();
+        assert!(
+            !system_meta
+                .component_access_set
+                .combined_access()
+                .has_any_read(),
+            "DeferredWorld in system {} conflicts with a previous access.",
+            system_meta.name,
+        );
         system_meta.component_access_set.write_all();
-        system_meta.set_has_deferred();
+        system_meta.archetype_component_access.write_all();
     }
 
     unsafe fn get_param<'world, 'state>(