Move allow unsafe_op_in_unsafe_fn to module level in bevy_ecs (#22134)

# Objective

- narrow the scope of the expect unsafe_op_in_unsafe_fn, so we can
progressively remove them.

## Testing

- cargo check showed no warnings

Author: hymm

crates/bevy_ecs/src/bundle/mod.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 //! Types for handling [`Bundle`]s.
 //!
 //! This module contains the [`Bundle`] trait and some other helper types.

crates/bevy_ecs/src/entity/clone_entities.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 use crate::{
     archetype::Archetype,
     bundle::{Bundle, BundleRemover, InsertMode},

crates/bevy_ecs/src/lib.rs

@@ -1,7 +1,3 @@
-#![expect(
-    unsafe_op_in_unsafe_fn,
-    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
-)]
 #![doc = include_str!("../README.md")]
 #![cfg_attr(
     any(docsrs, docsrs_dep),

crates/bevy_ecs/src/query/mod.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 //! Contains APIs for retrieving component data from the world.
 
 mod access;

crates/bevy_ecs/src/schedule/executor/multi_threaded.rs

@@ -448,12 +448,21 @@ impl ExecutorState {
         }
 
         #[cfg(feature = "hotpatching")]
-        let hotpatch_tick = context
-            .environment
-            .world_cell
-            .get_resource_ref::<HotPatchChanges>()
-            .map(|r| r.last_changed())
-            .unwrap_or_default();
+        #[expect(
+            clippy::undocumented_unsafe_blocks,
+            reason = "This actually could result in UB if a system tries to mutate
+            `HotPatchChanges`. We allow this as the resource only exists with the `hotpatching` feature.
+            and `hotpatching` should never be enabled in release."
+        )]
+        #[cfg(feature = "hotpatching")]
+        let hotpatch_tick = unsafe {
+            context
+                .environment
+                .world_cell
+                .get_resource_ref::<HotPatchChanges>()
+        }
+        .map(|r| r.last_changed())
+        .unwrap_or_default();
 
         // can't borrow since loop mutably borrows `self`
         let mut ready_systems = core::mem::take(&mut self.ready_systems_copy);

crates/bevy_ecs/src/storage/mod.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 //! Storage layouts for ECS data.
 //!
 //! This module implements the low-level collections that store data in a [`World`]. These all offer minimal and often

crates/bevy_ecs/src/system/combinator.rs

@@ -167,8 +167,6 @@ where
             input: SystemIn<S>,
             world: &mut PrivateUnsafeWorldCell,
         ) -> Result<S::Out, RunSystemError> {
-            #![deny(unsafe_op_in_unsafe_fn)]
-
             // SAFETY: see comment on `Func::combine` call
             match (|| unsafe {
                 system.validate_param_unsafe(world.0)?;

crates/bevy_ecs/src/system/system_param.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 pub use crate::change_detection::{NonSend, NonSendMut, Res, ResMut};
 use crate::{
     archetype::Archetypes,

crates/bevy_ecs/src/world/mod.rs

@@ -1,3 +1,8 @@
+#![expect(
+    unsafe_op_in_unsafe_fn,
+    reason = "See #11590. To be removed once all applicable unsafe code has an unsafe block with a safety comment."
+)]
+
 //! Defines the [`World`] and APIs for accessing it directly.
 
 pub(crate) mod command_queue;