Enable clippy::undocumented_unsafe_blocks warning across the workspace (#10646)

# Objective

Enables warning on `clippy::undocumented_unsafe_blocks` across the
workspace rather than only in `bevy_ecs`, `bevy_transform` and
`bevy_utils`. This adds a little awkwardness in a few areas of code that
have trivial safety or explain safety for multiple unsafe blocks with
one comment however automatically prevents these comments from being
missed.

## Solution

This adds `undocumented_unsafe_blocks = "warn"` to the workspace
`Cargo.toml` and fixes / adds a few missed safety comments. I also added
`#[allow(clippy::undocumented_unsafe_blocks)]` where the safety is
explained somewhere above.

There are a couple of safety comments I added I'm not 100% sure about in
`bevy_animation` and `bevy_render/src/view` and I'm not sure about the
use of `#[allow(clippy::undocumented_unsafe_blocks)]` compared to adding
comments like `// SAFETY: See above`.

Cargo.toml

@@ -32,6 +32,7 @@ members = [
 [workspace.lints.clippy]
 type_complexity = "allow"
 doc_markdown = "warn"
+undocumented_unsafe_blocks = "warn"
 
 [lints]
 workspace = true

crates/bevy_animation/src/lib.rs

@@ -646,6 +646,7 @@ fn apply_animation(
             let Ok(mut transform) = (unsafe { transforms.get_unchecked(target) }) else {
                 continue;
             };
+            // SAFETY: As above, there can't be other AnimationPlayers with this target so this fetch can't alias
             let mut morphs = unsafe { morphs.get_unchecked(target) };
             for curve in curves {
                 // Some curves have only one keyframe used to set a transform

crates/bevy_ecs/src/lib.rs

@@ -1,4 +1,3 @@
-#![warn(clippy::undocumented_unsafe_blocks)]
 #![warn(missing_docs)]
 #![doc = include_str!("../README.md")]
 

crates/bevy_mikktspace/src/lib.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::all)]
+#![allow(clippy::all, clippy::undocumented_unsafe_blocks)]
 
 use glam::{Vec2, Vec3};
 

crates/bevy_ptr/src/lib.rs

@@ -244,14 +244,14 @@ impl<'a, A: IsAligned> PtrMut<'a, A> {
     /// Gets a [`PtrMut`] from this with a smaller lifetime.
     #[inline]
     pub fn reborrow(&mut self) -> PtrMut<'_, A> {
-        // SAFE: the ptrmut we're borrowing from is assumed to be valid
+        // SAFETY: the ptrmut we're borrowing from is assumed to be valid
         unsafe { PtrMut::new(self.0) }
     }
 
     /// Gets an immutable reference from this mutable reference
     #[inline]
     pub fn as_ref(&self) -> Ptr<'_, A> {
-        // SAFE: The `PtrMut` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
+        // SAFETY: The `PtrMut` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
         unsafe { Ptr::new(self.0) }
     }
 }
@@ -327,14 +327,14 @@ impl<'a, A: IsAligned> OwningPtr<'a, A> {
     /// Gets an immutable pointer from this owned pointer.
     #[inline]
     pub fn as_ref(&self) -> Ptr<'_, A> {
-        // SAFE: The `Owning` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
+        // SAFETY: The `Owning` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
         unsafe { Ptr::new(self.0) }
     }
 
     /// Gets a mutable pointer from this owned pointer.
     #[inline]
     pub fn as_mut(&mut self) -> PtrMut<'_, A> {
-        // SAFE: The `Owning` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
+        // SAFETY: The `Owning` type's guarantees about the validity of this pointer are a superset of `Ptr` s guarantees
         unsafe { PtrMut::new(self.0) }
     }
 }

crates/bevy_render/src/lib.rs

@@ -251,6 +251,7 @@ impl Plugin for RenderPlugin {
                 app.insert_resource(FutureRendererResources(
                     future_renderer_resources_wrapper.clone(),
                 ));
+                // SAFETY: Plugins should be set up on the main thread.
                 unsafe { initialize_render_app(app) };
             }
             RenderCreation::Automatic(render_creation) => {
@@ -271,8 +272,8 @@ impl Plugin for RenderPlugin {
                             backends,
                             dx12_shader_compiler: settings.dx12_shader_compiler.clone(),
                         });
-                        let surface = primary_window.map(|wrapper| unsafe {
                         // SAFETY: Plugins should be set up on the main thread.
+                        let surface = primary_window.map(|wrapper| unsafe {
                             let handle = wrapper.get_handle();
                             instance
                                 .create_surface(&handle)
@@ -313,6 +314,7 @@ impl Plugin for RenderPlugin {
                     #[cfg(not(target_arch = "wasm32"))]
                     futures_lite::future::block_on(async_renderer);
 
+                    // SAFETY: Plugins should be set up on the main thread.
                     unsafe { initialize_render_app(app) };
                 }
             }
@@ -453,7 +455,7 @@ unsafe fn initialize_render_app(app: &mut App) {
                 "An entity was spawned after the entity list was cleared last frame and before the extract schedule began. This is not supported",
             );
 
-            // This is safe given the clear_entities call in the past frame and the assert above
+            // SAFETY: This is safe given the clear_entities call in the past frame and the assert above
             unsafe {
                 render_app
                     .world

crates/bevy_render/src/render_resource/resource_macros.rs

@@ -58,6 +58,7 @@ macro_rules! render_resource_wrapper {
         // If in future there is a case where a wrapper is required for a non-send/sync type
         // we can implement a macro variant that omits these manual Send + Sync impls
         unsafe impl Send for $wrapper_type {}
+        // SAFETY: As explained above, we ensure correctness by checking that $wgpu_type implements Send and Sync.
         unsafe impl Sync for $wrapper_type {}
         const _: () = {
             trait AssertSendSyncBound: Send + Sync {}

crates/bevy_render/src/view/window/mod.rs

@@ -252,12 +252,15 @@ pub fn prepare_windows(
         let surface_data = window_surfaces
             .surfaces
             .entry(window.entity)
-            .or_insert_with(|| unsafe {
+            .or_insert_with(|| {
+                // SAFETY: The window handles in ExtractedWindows will always be valid objects to create surfaces on
+                let surface = unsafe {
                     // NOTE: On some OSes this MUST be called from the main thread.
                     // As of wgpu 0.15, only fallible if the given window is a HTML canvas and obtaining a WebGPU or WebGL2 context fails.
-                let surface = render_instance
+                    render_instance
                         .create_surface(&window.handle.get_handle())
-                    .expect("Failed to create wgpu surface");
+                        .expect("Failed to create wgpu surface")
+                };
                 let caps = surface.get_capabilities(&render_adapter);
                 let formats = caps.formats;
                 // For future HDR output support, we'll need to request a format that supports HDR,

crates/bevy_tasks/src/task_pool.rs

@@ -353,12 +353,16 @@ impl TaskPool {
         // Any usages of the references passed into `Scope` must be accessed through
         // the transmuted reference for the rest of this function.
         let executor: &async_executor::Executor = &self.executor;
+        // SAFETY: As above, all futures must complete in this function so we can change the lifetime
         let executor: &'env async_executor::Executor = unsafe { mem::transmute(executor) };
+        // SAFETY: As above, all futures must complete in this function so we can change the lifetime
         let external_executor: &'env ThreadExecutor<'env> =
             unsafe { mem::transmute(external_executor) };
+        // SAFETY: As above, all futures must complete in this function so we can change the lifetime
         let scope_executor: &'env ThreadExecutor<'env> = unsafe { mem::transmute(scope_executor) };
         let spawned: ConcurrentQueue<FallibleTask<T>> = ConcurrentQueue::unbounded();
         // shadow the variable so that the owned value cannot be used for the rest of the function
+        // SAFETY: As above, all futures must complete in this function so we can change the lifetime
         let spawned: &'env ConcurrentQueue<
             FallibleTask<Result<T, Box<(dyn std::any::Any + Send)>>>,
         > = unsafe { mem::transmute(&spawned) };
@@ -373,6 +377,7 @@ impl TaskPool {
         };
 
         // shadow the variable so that the owned value cannot be used for the rest of the function
+        // SAFETY: As above, all futures must complete in this function so we can change the lifetime
         let scope: &'env Scope<'_, 'env, T> = unsafe { mem::transmute(&scope) };
 
         f(scope);

crates/bevy_transform/src/lib.rs

@@ -1,5 +1,4 @@
 #![warn(missing_docs)]
-#![warn(clippy::undocumented_unsafe_blocks)]
 #![doc = include_str!("../README.md")]
 
 pub mod commands;

crates/bevy_ui/src/ui_node.rs

@@ -1309,6 +1309,7 @@ pub struct GridPlacement {
 impl GridPlacement {
     pub const DEFAULT: Self = Self {
         start: None,
+        // SAFETY: This is trivially safe as 1 is non-zero.
         span: Some(unsafe { NonZeroU16::new_unchecked(1) }),
         end: None,
     };

crates/bevy_utils/src/lib.rs

@@ -4,7 +4,6 @@
 //!
 
 #![warn(missing_docs)]
-#![warn(clippy::undocumented_unsafe_blocks)]
 
 #[allow(missing_docs)]
 pub mod prelude {

crates/bevy_window/src/raw_handle.rs

@@ -34,6 +34,7 @@ impl RawHandleWrapper {
 // A recommendation for this pattern (and more context) is available here:
 // https://github.com/rust-windowing/raw-window-handle/issues/59
 unsafe impl Send for RawHandleWrapper {}
+// SAFETY: This is safe for the same reasons as the Send impl above.
 unsafe impl Sync for RawHandleWrapper {}
 
 /// A [`RawHandleWrapper`] that cannot be sent across threads.