comments

crates/bevy_ecs/src/world/unsafe_world_cell.rs

@@ -80,10 +80,12 @@ unsafe impl Send for UnsafeWorldCell<'_> {}
 unsafe impl Sync for UnsafeWorldCell<'_> {}
 
 impl<'w> UnsafeWorldCell<'w> {
+    /// Creates a [`UnsafeWorldCell`] that can be used to access everything immutably
     pub(crate) fn new_readonly(world: &'w World) -> Self {
         UnsafeWorldCell(world as *const World as *mut World, PhantomData)
     }
 
+    /// Creates [`UnsafeWorldCell`] that can be used to access everything mutably
     pub(crate) fn new_mutable(world: &'w mut World) -> Self {
         Self(world as *mut World, PhantomData)
     }
@@ -818,24 +820,37 @@ unsafe fn get_ticks(
 }
 
 #[inline]
-#[allow(unsafe_op_in_unsafe_fn)]
+/// # Safety:
+/// - the returned `Column` is only used in ways that the `world` has permission for.
+/// - the returned `Column` is only used in ways that would not conflict with any existing
+///   borrows of world data.
 unsafe fn fetch_table(
     world: UnsafeWorldCell<'_>,
     location: EntityLocation,
     component_id: ComponentId,
 ) -> Option<(&Column, TableRow)> {
     let archetype = &world.archetypes()[location.archetype_id];
-    let table = &world.unsafe_world().storages.tables[archetype.table_id()];
+    // SAFETY: caller ensures returned data is not misused and we have not created any borrows
+    // of component/resource data
+    let table = &unsafe { world.unsafe_world() }.storages.tables[archetype.table_id()];
     let components = table.get_column(component_id)?;
     let table_row = archetype.entity_table_row(location.archetype_row);
     Some((components, table_row))
 }
 
 #[inline]
-#[allow(unsafe_op_in_unsafe_fn)]
+/// # Safety:
+/// - the returned `ComponentSparseSet` is only used in ways that the `world` has permission for.
+/// - the returned `ComponentSparseSet` is only used in ways that would not conflict with any existing
+///   borrows of world data.
 unsafe fn fetch_sparse_set(
     world: UnsafeWorldCell<'_>,
     component_id: ComponentId,
 ) -> Option<&ComponentSparseSet> {
-    world.unsafe_world().storages.sparse_sets.get(component_id)
+    // SAFETY: caller ensures returned data is not misused and we have not created any borrows
+    // of component/resource data
+    unsafe { world.unsafe_world() }
+        .storages
+        .sparse_sets
+        .get(component_id)
 }