[Merged by Bors] - Allow iterating over with EntityRef over the entire World

crates/bevy_ecs/src/entity/mod.rs

@@ -575,6 +575,14 @@ impl Entities {
         }
     }
 
+    /// Gets the location of an entity without checking the validity of its index nor its generation.
+    ///
+    /// # Safety
+    /// `index` must correspond to an allocated entity.
+    pub(crate) unsafe fn get_unchecked(&self, index: u32) -> EntityLocation {
+        self.meta.get_unchecked(index as usize).location
+    }
+
     /// Updates the location of an [`Entity`]. This must be called when moving the components of
     /// the entity around in storage.
     ///

crates/bevy_ecs/src/world/mod.rs

@@ -323,11 +323,19 @@ impl World {
     ///
     /// This is useful in contexts where you only have read-only access to the [`World`].
     #[inline]
-    pub fn iter_entities(&self) -> impl Iterator<Item = Entity> + '_ {
+    pub fn iter_entities(&self) -> impl Iterator<Item = EntityRef<'_>> + '_ {
         self.archetypes
             .iter()
             .flat_map(|archetype| archetype.entities().iter())
-            .map(|archetype_entity| archetype_entity.entity())
+            .map(|archetype_entity| {
+                // SAFETY: The entity is already located in a Archetype, which means the entity
+                // must be properly allocated
+                let location = unsafe {
+                    self.entities
+                        .get_unchecked(archetype_entity.entity().index())
+                };
+                EntityRef::new(self, archetype_entity.entity(), location)
+            })
     }
 
     /// Retrieves an [`EntityMut`] that exposes read and write operations for the given `entity`.
@@ -1870,7 +1878,7 @@ mod tests {
         let iterate_and_count_entities = |world: &World, entity_counters: &mut HashMap<_, _>| {
             entity_counters.clear();
             for entity in world.iter_entities() {
-                let counter = entity_counters.entry(entity).or_insert(0);
+                let counter = entity_counters.entry(entity.id()).or_insert(0);
                 *counter += 1;
             }
         };

crates/bevy_scene/src/dynamic_scene.rs

@@ -46,7 +46,7 @@ impl DynamicScene {
         let mut builder =
             DynamicSceneBuilder::from_world_with_type_registry(world, type_registry.clone());
 
-        builder.extract_entities(world.iter_entities());
+        builder.extract_entities(world.iter_entities().map(|entity| entity.id()));
 
         builder.build()
     }