impl EntityBorrow for more types (#16917)

# Objective

Some types like `RenderEntity` and `MainEntity` are just wrappers around
`Entity`, so they should be able to implement
`EntityBorrow`/`TrustedEntityBorrow`. This allows using them with
`EntitySet` functionality.
The `EntityRef` family are more than direct wrappers around `Entity`,
but can still benefit from being unique in a collection.

## Solution

Implement `EntityBorrow` and `TrustedEntityBorrow` for simple `Entity`
newtypes and `EntityRef` types.
These impls are an explicit decision to have the `EntityRef` types
compare like just `Entity`.
`EntityWorldMut` is omitted from this impl, because it explicitly
contains a `&mut World` as well, and we do not ever use more than one at
a time.

Add `EntityBorrow` to the `bevy_ecs` prelude.

## Migration Guide

`NormalizedWindowRef::entity` has been replaced with an
`EntityBorrow::entity` impl.

crates/bevy_ecs/src/lib.rs

@@ -58,7 +58,7 @@ pub mod prelude {
         bundle::Bundle,
         change_detection::{DetectChanges, DetectChangesMut, Mut, Ref},
         component::{require, Component},
-        entity::{Entity, EntityMapper},
+        entity::{Entity, EntityBorrow, EntityMapper},
         event::{Event, EventMutator, EventReader, EventWriter, Events},
         name::{Name, NameOrEntity},
         observer::{CloneEntityWithObserversExt, Observer, Trigger},

crates/bevy_ecs/src/query/iter.rs

@@ -1,11 +1,15 @@
 use super::{QueryData, QueryFilter, ReadOnlyQueryData};
 use crate::{
     archetype::{Archetype, ArchetypeEntity, Archetypes},
+    bundle::Bundle,
     component::Tick,
     entity::{Entities, Entity, EntityBorrow, EntitySet, EntitySetIterator},
     query::{ArchetypeFilter, DebugCheckedUnwrap, QueryState, StorageId},
     storage::{Table, TableRow, Tables},
-    world::unsafe_world_cell::UnsafeWorldCell,
+    world::{
+        unsafe_world_cell::UnsafeWorldCell, EntityMut, EntityMutExcept, EntityRef, EntityRefExcept,
+        FilteredEntityMut, FilteredEntityRef,
+    },
 };
 use alloc::vec::Vec;
 use core::{
@@ -1105,6 +1109,36 @@ impl<'w, 's, D: QueryData, F: QueryFilter> FusedIterator for QueryIter<'w, 's, D
 // SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
 unsafe impl<'w, 's, F: QueryFilter> EntitySetIterator for QueryIter<'w, 's, Entity, F> {}
 
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter> EntitySetIterator for QueryIter<'w, 's, EntityRef<'_>, F> {}
+
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter> EntitySetIterator for QueryIter<'w, 's, EntityMut<'_>, F> {}
+
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter> EntitySetIterator
+    for QueryIter<'w, 's, FilteredEntityRef<'_>, F>
+{
+}
+
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter> EntitySetIterator
+    for QueryIter<'w, 's, FilteredEntityMut<'_>, F>
+{
+}
+
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter, B: Bundle> EntitySetIterator
+    for QueryIter<'w, 's, EntityRefExcept<'_, B>, F>
+{
+}
+
+// SAFETY: [`QueryIter`] is guaranteed to return every matching entity once and only once.
+unsafe impl<'w, 's, F: QueryFilter, B: Bundle> EntitySetIterator
+    for QueryIter<'w, 's, EntityMutExcept<'_, B>, F>
+{
+}
+
 impl<'w, 's, D: QueryData, F: QueryFilter> Debug for QueryIter<'w, 's, D, F> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         f.debug_struct("QueryIter").finish()

crates/bevy_ecs/src/world/entity_ref.rs

@@ -3,7 +3,9 @@ use crate::{
     bundle::{Bundle, BundleId, BundleInfo, BundleInserter, DynamicBundle, InsertMode},
     change_detection::MutUntyped,
     component::{Component, ComponentId, ComponentTicks, Components, Mutable, StorageType},
-    entity::{Entities, Entity, EntityCloneBuilder, EntityLocation},
+    entity::{
+        Entities, Entity, EntityBorrow, EntityCloneBuilder, EntityLocation, TrustedEntityBorrow,
+    },
     event::Event,
     observer::Observer,
     query::{Access, ReadOnlyQueryData},
@@ -17,7 +19,13 @@ use bevy_ptr::{OwningPtr, Ptr};
 use bevy_utils::{HashMap, HashSet};
 #[cfg(feature = "track_change_detection")]
 use core::panic::Location;
-use core::{any::TypeId, marker::PhantomData, mem::MaybeUninit};
+use core::{
+    any::TypeId,
+    cmp::Ordering,
+    hash::{Hash, Hasher},
+    marker::PhantomData,
+    mem::MaybeUninit,
+};
 use thiserror::Error;
 
 use super::{unsafe_world_cell::UnsafeEntityCell, Ref, ON_REMOVE, ON_REPLACE};
@@ -369,6 +377,44 @@ impl<'a> TryFrom<&'a FilteredEntityMut<'_>> for EntityRef<'a> {
     }
 }
 
+impl PartialEq for EntityRef<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl Eq for EntityRef<'_> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl PartialOrd for EntityRef<'_> {
+    /// [`EntityRef`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl Ord for EntityRef<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl Hash for EntityRef<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl EntityBorrow for EntityRef<'_> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl TrustedEntityBorrow for EntityRef<'_> {}
+
 /// Provides mutable access to a single entity and all of its components.
 ///
 /// Contrast with [`EntityWorldMut`], which allows adding and removing components,
@@ -869,6 +915,44 @@ impl<'a> TryFrom<&'a mut FilteredEntityMut<'_>> for EntityMut<'a> {
     }
 }
 
+impl PartialEq for EntityMut<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl Eq for EntityMut<'_> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl PartialOrd for EntityMut<'_> {
+    /// [`EntityMut`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl Ord for EntityMut<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl Hash for EntityMut<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl EntityBorrow for EntityMut<'_> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl TrustedEntityBorrow for EntityMut<'_> {}
+
 /// A mutable reference to a particular [`Entity`], and the entire world.
 ///
 /// This is essentially a performance-optimized `(Entity, &mut World)` tuple,
@@ -2969,6 +3053,44 @@ impl<'a> From<&'a EntityWorldMut<'_>> for FilteredEntityRef<'a> {
     }
 }
 
+impl PartialEq for FilteredEntityRef<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl Eq for FilteredEntityRef<'_> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl PartialOrd for FilteredEntityRef<'_> {
+    /// [`FilteredEntityRef`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl Ord for FilteredEntityRef<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl Hash for FilteredEntityRef<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl EntityBorrow for FilteredEntityRef<'_> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl TrustedEntityBorrow for FilteredEntityRef<'_> {}
+
 /// Provides mutable access to a single entity and some of its components defined by the contained [`Access`].
 ///
 /// To define the access when used as a [`QueryData`](crate::query::QueryData),
@@ -3258,6 +3380,44 @@ impl<'a> From<&'a mut EntityWorldMut<'_>> for FilteredEntityMut<'a> {
     }
 }
 
+impl PartialEq for FilteredEntityMut<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl Eq for FilteredEntityMut<'_> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl PartialOrd for FilteredEntityMut<'_> {
+    /// [`FilteredEntityMut`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl Ord for FilteredEntityMut<'_> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl Hash for FilteredEntityMut<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl EntityBorrow for FilteredEntityMut<'_> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl TrustedEntityBorrow for FilteredEntityMut<'_> {}
+
 /// Error type returned by [`TryFrom`] conversions from filtered entity types
 /// ([`FilteredEntityRef`]/[`FilteredEntityMut`]) to full-access entity types
 /// ([`EntityRef`]/[`EntityMut`]).
@@ -3361,6 +3521,44 @@ where
     }
 }
 
+impl<B: Bundle> PartialEq for EntityRefExcept<'_, B> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl<B: Bundle> Eq for EntityRefExcept<'_, B> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl<B: Bundle> PartialOrd for EntityRefExcept<'_, B> {
+    /// [`EntityRefExcept`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl<B: Bundle> Ord for EntityRefExcept<'_, B> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl<B: Bundle> Hash for EntityRefExcept<'_, B> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl<B: Bundle> EntityBorrow for EntityRefExcept<'_, B> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl<B: Bundle> TrustedEntityBorrow for EntityRefExcept<'_, B> {}
+
 /// Provides mutable access to all components of an entity, with the exception
 /// of an explicit set.
 ///
@@ -3464,6 +3662,44 @@ where
     }
 }
 
+impl<B: Bundle> PartialEq for EntityMutExcept<'_, B> {
+    fn eq(&self, other: &Self) -> bool {
+        self.entity() == other.entity()
+    }
+}
+
+impl<B: Bundle> Eq for EntityMutExcept<'_, B> {}
+
+#[expect(clippy::non_canonical_partial_ord_impl)]
+impl<B: Bundle> PartialOrd for EntityMutExcept<'_, B> {
+    /// [`EntityMutExcept`]'s comparison trait implementations match the underlying [`Entity`],
+    /// and cannot discern between different worlds.
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.entity().partial_cmp(&other.entity())
+    }
+}
+
+impl<B: Bundle> Ord for EntityMutExcept<'_, B> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.entity().cmp(&other.entity())
+    }
+}
+
+impl<B: Bundle> Hash for EntityMutExcept<'_, B> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.entity().hash(state);
+    }
+}
+
+impl<B: Bundle> EntityBorrow for EntityMutExcept<'_, B> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: This type represents one Entity. We implement the comparison traits based on that Entity.
+unsafe impl<B: Bundle> TrustedEntityBorrow for EntityMutExcept<'_, B> {}
+
 fn bundle_contains_component<B>(components: &Components, query_id: ComponentId) -> bool
 where
     B: Bundle,

crates/bevy_ecs/src/world/unsafe_world_cell.rs

@@ -8,7 +8,7 @@ use crate::{
     bundle::Bundles,
     change_detection::{MaybeUnsafeCellLocation, MutUntyped, Ticks, TicksMut},
     component::{ComponentId, ComponentTicks, Components, Mutable, StorageType, Tick, TickCells},
-    entity::{Entities, Entity, EntityLocation},
+    entity::{Entities, Entity, EntityBorrow, EntityLocation},
     observer::Observers,
     prelude::Component,
     query::{DebugCheckedUnwrap, ReadOnlyQueryData},
@@ -1183,3 +1183,9 @@ unsafe fn get_ticks(
         StorageType::SparseSet => world.fetch_sparse_set(component_id)?.get_ticks(entity),
     }
 }
+
+impl EntityBorrow for UnsafeEntityCell<'_> {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}

crates/bevy_render/src/camera/camera.rs

@@ -19,7 +19,7 @@ use bevy_derive::{Deref, DerefMut};
 use bevy_ecs::{
     change_detection::DetectChanges,
     component::{Component, ComponentId, Mutable},
-    entity::Entity,
+    entity::{Entity, EntityBorrow},
     event::EventReader,
     prelude::{require, With},
     query::Has,

crates/bevy_render/src/camera/camera_driver_node.rs

@@ -4,7 +4,7 @@ use crate::{
     renderer::RenderContext,
     view::ExtractedWindows,
 };
-use bevy_ecs::{prelude::QueryState, world::World};
+use bevy_ecs::{entity::EntityBorrow, prelude::QueryState, world::World};
 use bevy_utils::HashSet;
 use wgpu::{LoadOp, Operations, RenderPassColorAttachment, RenderPassDescriptor, StoreOp};
 

crates/bevy_render/src/sync_world.rs

@@ -3,7 +3,7 @@ use bevy_derive::{Deref, DerefMut};
 use bevy_ecs::entity::EntityHash;
 use bevy_ecs::{
     component::Component,
-    entity::Entity,
+    entity::{Entity, EntityBorrow, TrustedEntityBorrow},
     observer::Trigger,
     query::With,
     reflect::ReflectComponent,
@@ -140,6 +140,15 @@ impl From<Entity> for RenderEntity {
     }
 }
 
+impl EntityBorrow for RenderEntity {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: RenderEntity is a newtype around Entity that derives its comparison traits.
+unsafe impl TrustedEntityBorrow for RenderEntity {}
+
 /// Component added on the render world entities to keep track of the corresponding main world entity.
 ///
 /// Can also be used as a newtype wrapper for main world entities.
@@ -158,6 +167,15 @@ impl From<Entity> for MainEntity {
     }
 }
 
+impl EntityBorrow for MainEntity {
+    fn entity(&self) -> Entity {
+        self.id()
+    }
+}
+
+// SAFETY: RenderEntity is a newtype around Entity that derives its comparison traits.
+unsafe impl TrustedEntityBorrow for MainEntity {}
+
 /// A [`HashMap`](hashbrown::HashMap) pre-configured to use [`EntityHash`] hashing with a [`MainEntity`].
 pub type MainEntityHashMap<V> = hashbrown::HashMap<MainEntity, V, EntityHash>;
 

crates/bevy_ui/src/focus.rs

@@ -3,7 +3,7 @@ use crate::{
 };
 use bevy_ecs::{
     change_detection::DetectChangesMut,
-    entity::Entity,
+    entity::{Entity, EntityBorrow},
     prelude::{Component, With},
     query::QueryData,
     reflect::ReflectComponent,

crates/bevy_ui/src/layout/mod.rs

@@ -5,7 +5,7 @@ use crate::{
 };
 use bevy_ecs::{
     change_detection::{DetectChanges, DetectChangesMut},
-    entity::{Entity, EntityHashMap, EntityHashSet},
+    entity::{Entity, EntityBorrow, EntityHashMap, EntityHashSet},
     event::EventReader,
     query::With,
     removal_detection::RemovedComponents,

crates/bevy_window/src/window.rs

@@ -1,7 +1,7 @@
 use core::num::NonZero;
 
 use bevy_ecs::{
-    entity::{Entity, VisitEntities, VisitEntitiesMut},
+    entity::{Entity, EntityBorrow, VisitEntities, VisitEntitiesMut},
     prelude::{Component, ReflectComponent},
 };
 use bevy_math::{CompassOctant, DVec2, IVec2, UVec2, Vec2};
@@ -88,9 +88,8 @@ impl VisitEntitiesMut for WindowRef {
 )]
 pub struct NormalizedWindowRef(Entity);
 
-impl NormalizedWindowRef {
-    /// Fetch the entity of this window reference
-    pub fn entity(&self) -> Entity {
+impl EntityBorrow for NormalizedWindowRef {
+    fn entity(&self) -> Entity {
         self.0
     }
 }