wip

.github/workflows/ci.yml

@@ -244,9 +244,9 @@ jobs:
       - name: Install Rust
         run: rustup toolchain install nightly --component miri && rustup default nightly
       # futures-executor uses boxed futures so many tests trigger https://github.com/rust-lang/miri/issues/1038
-      - run: cargo miri test --workspace --exclude futures-executor --all-features
+      - run: cargo miri test --workspace --exclude futures-executor --all-features --no-fail-fast
         env:
-          MIRIFLAGS: -Zmiri-disable-isolation # TODO: use -Zmiri-tag-raw-pointers
+          MIRIFLAGS: -Zmiri-disable-isolation -Zmiri-tag-raw-pointers
 
   san:
     name: cargo test -Z sanitizer=${{ matrix.sanitizer }}

futures-task/src/future_obj.rs

@@ -224,7 +224,7 @@ mod if_alloc {
         }
 
         unsafe fn drop(ptr: *mut (dyn Future<Output = T> + 'a)) {
-            drop(Box::from_raw(ptr as *mut F))
+            drop(Box::from_raw(ptr.cast::<F>()))
         }
     }
 
@@ -252,10 +252,9 @@ mod if_alloc {
     where
         F: Future<Output = T> + 'a,
     {
-        fn into_raw(mut self) -> *mut (dyn Future<Output = T> + 'a) {
-            let ptr = unsafe { self.as_mut().get_unchecked_mut() as *mut _ };
-            mem::forget(self);
-            ptr
+        fn into_raw(self) -> *mut (dyn Future<Output = T> + 'a) {
+            let mut this = mem::ManuallyDrop::new(self);
+            unsafe { this.as_mut().get_unchecked_mut() as *mut _ }
         }
 
         unsafe fn drop(ptr: *mut (dyn Future<Output = T> + 'a)) {
@@ -264,10 +263,9 @@ mod if_alloc {
     }
 
     unsafe impl<'a, T: 'a> UnsafeFutureObj<'a, T> for Pin<Box<dyn Future<Output = T> + 'a>> {
-        fn into_raw(mut self) -> *mut (dyn Future<Output = T> + 'a) {
-            let ptr = unsafe { self.as_mut().get_unchecked_mut() as *mut _ };
-            mem::forget(self);
-            ptr
+        fn into_raw(self) -> *mut (dyn Future<Output = T> + 'a) {
+            let mut this = mem::ManuallyDrop::new(self);
+            unsafe { this.as_mut().get_unchecked_mut() as *mut _ }
         }
 
         unsafe fn drop(ptr: *mut (dyn Future<Output = T> + 'a)) {
@@ -276,10 +274,9 @@ mod if_alloc {
     }
 
     unsafe impl<'a, T: 'a> UnsafeFutureObj<'a, T> for Pin<Box<dyn Future<Output = T> + Send + 'a>> {
-        fn into_raw(mut self) -> *mut (dyn Future<Output = T> + 'a) {
-            let ptr = unsafe { self.as_mut().get_unchecked_mut() as *mut _ };
-            mem::forget(self);
-            ptr
+        fn into_raw(self) -> *mut (dyn Future<Output = T> + 'a) {
+            let mut this = mem::ManuallyDrop::new(self);
+            unsafe { this.as_mut().get_unchecked_mut() as *mut _ }
         }
 
         unsafe fn drop(ptr: *mut (dyn Future<Output = T> + 'a)) {

futures-task/src/waker.rs

@@ -20,7 +20,7 @@ pub fn waker<W>(wake: Arc<W>) -> Waker
 where
     W: ArcWake + 'static,
 {
-    let ptr = Arc::into_raw(wake) as *const ();
+    let ptr = Arc::into_raw(wake).cast::<()>();
 
     unsafe { Waker::from_raw(RawWaker::new(ptr, waker_vtable::<W>())) }
 }
@@ -31,7 +31,7 @@ where
 #[allow(clippy::redundant_clone)] // The clone here isn't actually redundant.
 unsafe fn increase_refcount<T: ArcWake>(data: *const ()) {
     // Retain Arc, but don't touch refcount by wrapping in ManuallyDrop
-    let arc = mem::ManuallyDrop::new(Arc::<T>::from_raw(data as *const T));
+    let arc = mem::ManuallyDrop::new(Arc::<T>::from_raw(data.cast::<T>()));
     // Now increase refcount, but don't drop new refcount either
     let _arc_clone: mem::ManuallyDrop<_> = arc.clone();
 }
@@ -43,17 +43,17 @@ unsafe fn clone_arc_raw<T: ArcWake>(data: *const ()) -> RawWaker {
 }
 
 unsafe fn wake_arc_raw<T: ArcWake>(data: *const ()) {
-    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    let arc: Arc<T> = Arc::from_raw(data.cast::<T>());
     ArcWake::wake(arc);
 }
 
 // used by `waker_ref`
 unsafe fn wake_by_ref_arc_raw<T: ArcWake>(data: *const ()) {
     // Retain Arc, but don't touch refcount by wrapping in ManuallyDrop
-    let arc = mem::ManuallyDrop::new(Arc::<T>::from_raw(data as *const T));
+    let arc = mem::ManuallyDrop::new(Arc::<T>::from_raw(data.cast::<T>()));
     ArcWake::wake_by_ref(&arc);
 }
 
 unsafe fn drop_arc_raw<T: ArcWake>(data: *const ()) {
-    drop(Arc::<T>::from_raw(data as *const T))
+    drop(Arc::<T>::from_raw(data.cast::<T>()))
 }

futures-task/src/waker_ref.rs

@@ -55,7 +55,7 @@ where
 {
     // simply copy the pointer instead of using Arc::into_raw,
     // as we don't actually keep a refcount by using ManuallyDrop.<
-    let ptr = (&**wake as *const W) as *const ();
+    let ptr = Arc::as_ptr(wake).cast::<()>();
 
     let waker =
         ManuallyDrop::new(unsafe { Waker::from_raw(RawWaker::new(ptr, waker_vtable::<W>())) });

futures-util/src/stream/futures_unordered/mod.rs

@@ -150,7 +150,7 @@ impl<Fut> FuturesUnordered<Fut> {
             queued: AtomicBool::new(true),
             ready_to_run_queue: Weak::new(),
         });
-        let stub_ptr = &*stub as *const Task<Fut>;
+        let stub_ptr = Arc::as_ptr(&stub);
         let ready_to_run_queue = Arc::new(ReadyToRunQueue {
             waker: AtomicWaker::new(),
             head: AtomicPtr::new(stub_ptr as *mut _),
@@ -403,7 +403,7 @@ impl<Fut> FuturesUnordered<Fut> {
         // The `ReadyToRunQueue` stub is never inserted into the `head_all`
         // list, and its pointer value will remain valid for the lifetime of
         // this `FuturesUnordered`, so we can make use of its value here.
-        &*self.ready_to_run_queue.stub as *const _ as *mut _
+        Arc::as_ptr(&self.ready_to_run_queue.stub) as *mut _
     }
 }