Fix miri test failure

crossbeam-channel/tests/golang.rs

@@ -1580,9 +1580,7 @@ mod race_chan_test {
 }
 
 // https://github.com/golang/go/blob/master/test/ken/chan.go
-#[cfg(not(miri))] // Miri is too slow
 mod chan {
-
     use super::*;
 
     const MESSAGES_PER_CHANEL: u32 = 76;
@@ -2052,6 +2050,7 @@ mod chan {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)] // Miri is too slow
     fn main() {
         let mut ctx = Context {
             nproc: Arc::new(Mutex::new(0)),

crossbeam-channel/tests/list.rs

@@ -67,6 +67,7 @@ fn len_empty_full() {
 }
 
 #[test]
+#[cfg_attr(miri, ignore)] // this test makes timing assumptions, but Miri is so slow it violates them
 fn try_recv() {
     let (s, r) = unbounded();
 

crossbeam-channel/tests/select.rs

@@ -408,7 +408,6 @@ fn both_ready() {
     .unwrap();
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn loop_try() {
     const RUNS: usize = 20;

crossbeam-channel/tests/select_macro.rs

@@ -284,7 +284,6 @@ fn both_ready() {
     .unwrap();
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn loop_try() {
     const RUNS: usize = 20;

crossbeam-channel/tests/zero.rs

@@ -328,9 +328,11 @@ fn stress_oneshot() {
     }
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn stress_iter() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 1000;
 
     let (request_s, request_r) = bounded(0);
@@ -485,7 +487,7 @@ fn fairness() {
 #[test]
 fn fairness_duplicates() {
     #[cfg(miri)]
-    const COUNT: usize = 50;
+    const COUNT: usize = 100;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 

crossbeam-deque/src/deque.rs

@@ -3,7 +3,7 @@ use std::cmp;
 use std::fmt;
 use std::iter::FromIterator;
 use std::marker::PhantomData;
-use std::mem::{self, MaybeUninit};
+use std::mem::{self, ManuallyDrop, MaybeUninit};
 use std::ptr;
 use std::sync::atomic::{self, AtomicIsize, AtomicPtr, AtomicUsize, Ordering};
 use std::sync::Arc;
@@ -38,9 +38,8 @@ impl<T> Buffer<T> {
     fn alloc(cap: usize) -> Buffer<T> {
         debug_assert_eq!(cap, cap.next_power_of_two());
 
-        let mut v = Vec::with_capacity(cap);
+        let mut v = ManuallyDrop::new(Vec::with_capacity(cap));
         let ptr = v.as_mut_ptr();
-        mem::forget(v);
 
         Buffer { ptr, cap }
     }

crossbeam-epoch/src/atomic.rs

@@ -305,6 +305,7 @@ impl<T> Atomic<T> {
     /// use crossbeam_epoch::Atomic;
     ///
     /// let a = Atomic::new(1234);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn new(init: T) -> Atomic<T> {
         Self::init(init)
@@ -320,6 +321,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// use crossbeam_epoch::Atomic;
     ///
     /// let a = Atomic::<i32>::init(1234);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn init(init: T::Init) -> Atomic<T> {
         Self::from(Owned::init(init))
@@ -373,6 +375,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// let a = Atomic::new(1234);
     /// let guard = &epoch::pin();
     /// let p = a.load(SeqCst, guard);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn load<'g>(&self, ord: Ordering, _: &'g Guard) -> Shared<'g, T> {
         unsafe { Shared::from_usize(self.data.load(ord)) }
@@ -398,6 +401,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// let a = Atomic::new(1234);
     /// let guard = &epoch::pin();
     /// let p = a.load_consume(guard);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn load_consume<'g>(&self, _: &'g Guard) -> Shared<'g, T> {
         unsafe { Shared::from_usize(self.data.load_consume()) }
@@ -415,8 +419,10 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// use std::sync::atomic::Ordering::SeqCst;
     ///
     /// let a = Atomic::new(1234);
+    /// # unsafe { drop(a.load(SeqCst, &crossbeam_epoch::pin()).into_owned()); } // avoid leak
     /// a.store(Shared::null(), SeqCst);
     /// a.store(Owned::new(1234), SeqCst);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn store<P: Pointer<T>>(&self, new: P, ord: Ordering) {
         self.data.store(new.into_usize(), ord);
@@ -437,6 +443,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// let a = Atomic::new(1234);
     /// let guard = &epoch::pin();
     /// let p = a.swap(Shared::null(), SeqCst, guard);
+    /// # unsafe { drop(p.into_owned()); } // avoid leak
     /// ```
     pub fn swap<'g, P: Pointer<T>>(&self, new: P, ord: Ordering, _: &'g Guard) -> Shared<'g, T> {
         unsafe { Shared::from_usize(self.data.swap(new.into_usize(), ord)) }
@@ -471,6 +478,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// let curr = a.load(SeqCst, guard);
     /// let res1 = a.compare_exchange(curr, Shared::null(), SeqCst, SeqCst, guard);
     /// let res2 = a.compare_exchange(curr, Owned::new(5678), SeqCst, SeqCst, guard);
+    /// # unsafe { drop(curr.into_owned()); } // avoid leak
     /// ```
     pub fn compare_exchange<'g, P>(
         &self,
@@ -526,6 +534,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     ///
     /// let mut new = Owned::new(5678);
     /// let mut ptr = a.load(SeqCst, guard);
+    /// # unsafe { drop(a.load(SeqCst, guard).into_owned()); } // avoid leak
     /// loop {
     ///     match a.compare_exchange_weak(ptr, new, SeqCst, SeqCst, guard) {
     ///         Ok(p) => {
@@ -546,6 +555,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     ///         Err(err) => curr = err.current,
     ///     }
     /// }
+    /// # unsafe { drop(curr.into_owned()); } // avoid leak
     /// ```
     pub fn compare_exchange_weak<'g, P>(
         &self,
@@ -608,6 +618,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     ///
     /// let res2 = a.fetch_update(SeqCst, SeqCst, guard, |x| None);
     /// assert!(res2.is_err());
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn fetch_update<'g, F>(
         &self,
@@ -666,6 +677,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     /// let curr = a.load(SeqCst, guard);
     /// let res1 = a.compare_and_set(curr, Shared::null(), SeqCst, guard);
     /// let res2 = a.compare_and_set(curr, Owned::new(5678), SeqCst, guard);
+    /// # unsafe { drop(curr.into_owned()); } // avoid leak
     /// ```
     // TODO: remove in the next major version.
     #[allow(deprecated)]
@@ -723,6 +735,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     ///
     /// let mut new = Owned::new(5678);
     /// let mut ptr = a.load(SeqCst, guard);
+    /// # unsafe { drop(a.load(SeqCst, guard).into_owned()); } // avoid leak
     /// loop {
     ///     match a.compare_and_set_weak(ptr, new, SeqCst, guard) {
     ///         Ok(p) => {
@@ -743,6 +756,7 @@ impl<T: ?Sized + Pointable> Atomic<T> {
     ///         Err(err) => curr = err.current,
     ///     }
     /// }
+    /// # unsafe { drop(curr.into_owned()); } // avoid leak
     /// ```
     // TODO: remove in the next major version.
     #[allow(deprecated)]
@@ -925,6 +939,7 @@ impl<T: ?Sized + Pointable> From<Owned<T>> for Atomic<T> {
     /// use crossbeam_epoch::{Atomic, Owned};
     ///
     /// let a = Atomic::<i32>::from(Owned::new(1234));
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     fn from(owned: Owned<T>) -> Self {
         let data = owned.data;
@@ -1108,6 +1123,7 @@ impl<T: ?Sized + Pointable> Owned<T> {
     /// let o = Owned::new(1234);
     /// let guard = &epoch::pin();
     /// let p = o.into_shared(guard);
+    /// # unsafe { drop(p.into_owned()); } // avoid leak
     /// ```
     #[allow(clippy::needless_lifetimes)]
     pub fn into_shared<'g>(self, _: &'g Guard) -> Shared<'g, T> {
@@ -1291,6 +1307,7 @@ impl<'g, T> Shared<'g, T> {
     /// let guard = &epoch::pin();
     /// let p = a.load(SeqCst, guard);
     /// assert_eq!(p.as_raw(), raw);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn as_raw(&self) -> *const T {
         let (raw, _) = decompose_tag::<T>(self.data);
@@ -1329,6 +1346,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// assert!(a.load(SeqCst, guard).is_null());
     /// a.store(Owned::new(1234), SeqCst);
     /// assert!(!a.load(SeqCst, guard).is_null());
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn is_null(&self) -> bool {
         let (raw, _) = decompose_tag::<T>(self.data);
@@ -1365,6 +1383,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// unsafe {
     ///     assert_eq!(p.deref(), &1234);
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub unsafe fn deref(&self) -> &'g T {
         let (raw, _) = decompose_tag::<T>(self.data);
@@ -1406,6 +1425,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// unsafe {
     ///     assert_eq!(p.deref(), &vec![1, 2, 3, 4, 5]);
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub unsafe fn deref_mut(&mut self) -> &'g mut T {
         let (raw, _) = decompose_tag::<T>(self.data);
@@ -1442,6 +1462,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// unsafe {
     ///     assert_eq!(p.as_ref(), Some(&1234));
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub unsafe fn as_ref(&self) -> Option<&'g T> {
         let (raw, _) = decompose_tag::<T>(self.data);
@@ -1493,6 +1514,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// let guard = &epoch::pin();
     /// let p = a.load(SeqCst, guard);
     /// assert_eq!(p.tag(), 2);
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn tag(&self) -> usize {
         let (_, tag) = decompose_tag::<T>(self.data);
@@ -1516,6 +1538,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> {
     /// assert_eq!(p1.tag(), 0);
     /// assert_eq!(p2.tag(), 2);
     /// assert_eq!(p1.as_raw(), p2.as_raw());
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn with_tag(&self, tag: usize) -> Shared<'g, T> {
         unsafe { Self::from_usize(compose_tag::<T>(self.data, tag)) }
@@ -1536,6 +1559,7 @@ impl<T> From<*const T> for Shared<'_, T> {
     ///
     /// let p = Shared::from(Box::into_raw(Box::new(1234)) as *const _);
     /// assert!(!p.is_null());
+    /// # unsafe { drop(p.into_owned()); } // avoid leak
     /// ```
     fn from(raw: *const T) -> Self {
         let raw = raw as usize;

crossbeam-epoch/src/collector.rs

@@ -111,7 +111,7 @@ impl fmt::Debug for LocalHandle {
 
 #[cfg(all(test, not(crossbeam_loom)))]
 mod tests {
-    use std::mem;
+    use std::mem::ManuallyDrop;
     use std::sync::atomic::{AtomicUsize, Ordering};
 
     use crossbeam_utils::thread;
@@ -402,15 +402,13 @@ mod tests {
                 v.push(i as i32);
             }
 
-            let ptr = v.as_mut_ptr() as usize;
             let len = v.len();
+            let ptr = ManuallyDrop::new(v).as_mut_ptr() as usize;
             guard.defer_unchecked(move || {
                 drop(Vec::from_raw_parts(ptr as *const i32 as *mut i32, len, len));
                 DESTROYS.fetch_add(len, Ordering::Relaxed);
             });
             guard.flush();
-
-            mem::forget(v);
         }
 
         while DESTROYS.load(Ordering::Relaxed) < COUNT {

crossbeam-epoch/src/guard.rs

@@ -46,6 +46,7 @@ use crate::internal::Local;
 /// if let Some(num) = unsafe { p.as_ref() } {
 ///     println!("The number is {}.", num);
 /// }
+/// # unsafe { drop(a.into_owned()); } // avoid leak
 /// ```
 ///
 /// # Multiple guards
@@ -184,6 +185,7 @@ impl Guard {
     ///         });
     ///     }
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub unsafe fn defer_unchecked<F, R>(&self, f: F)
     where
@@ -263,6 +265,7 @@ impl Guard {
     ///         guard.defer_destroy(p);
     ///     }
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub unsafe fn defer_destroy<T>(&self, ptr: Shared<'_, T>) {
         self.defer_unchecked(move || ptr.into_owned());
@@ -320,6 +323,7 @@ impl Guard {
     ///     let p = a.load(SeqCst, &guard);
     ///     assert_eq!(unsafe { p.as_ref() }, Some(&777));
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn repin(&mut self) {
         if let Some(local) = unsafe { self.local.as_ref() } {
@@ -356,6 +360,7 @@ impl Guard {
     ///     let p = a.load(SeqCst, &guard);
     ///     assert_eq!(unsafe { p.as_ref() }, Some(&777));
     /// }
+    /// # unsafe { drop(a.into_owned()); } // avoid leak
     /// ```
     pub fn repin_after<F, R>(&mut self, f: F) -> R
     where
@@ -451,6 +456,7 @@ impl fmt::Debug for Guard {
 ///
 ///     // Dropping `dummy` doesn't affect the current thread - it's just a noop.
 /// }
+/// # unsafe { drop(a.into_owned()); } // avoid leak
 /// ```
 ///
 /// The most common use of this function is when constructing or destructing a data structure.

crossbeam-queue/tests/array_queue.rs

@@ -193,9 +193,11 @@ fn spsc_ring_buffer() {
     }
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn mpmc() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
 
@@ -230,9 +232,11 @@ fn mpmc() {
     }
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn mpmc_ring_buffer() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
 

crossbeam-queue/tests/seg_queue.rs

@@ -82,9 +82,11 @@ fn spsc() {
     .unwrap();
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn mpmc() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
 

crossbeam-utils/src/atomic/atomic_cell.rs

@@ -1009,10 +1009,11 @@ where
                 // discard the data when a data race is detected. The proper solution would be to
                 // do atomic reads and atomic writes, but we can't atomically read and write all
                 // kinds of data since `AtomicU8` is not available on stable Rust yet.
-                let val = ptr::read_volatile(src);
+                // Load as `MaybeUninit` because we may load a value that is not valid as `T`.
+                let val = ptr::read_volatile(src as *mut MaybeUninit<T>);
 
                 if lock.validate_read(stamp) {
-                    return val;
+                    return val.assume_init();
                 }
             }