Use maybe-uninit crate to bridge backwards compatibility issues with …

…MaybeUninit

crossbeam-channel/Cargo.toml

@@ -15,6 +15,9 @@ description = "Multi-producer multi-consumer channels for message passing"
 keywords = ["channel", "mpmc", "select", "golang", "message"]
 categories = ["algorithms", "concurrency", "data-structures"]
 
+[dependencies]
+maybe-uninit = "2.0.0"
+
 [dependencies.crossbeam-utils]
 version = "0.7"
 path = "../crossbeam-utils"

crossbeam-channel/src/flavors/array.rs

@@ -15,13 +15,15 @@
 
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
-use std::mem::{self, MaybeUninit};
+use std::mem;
 use std::ptr;
 use std::sync::atomic::{self, AtomicUsize, Ordering};
 use std::time::Instant;
 
 use crossbeam_utils::{Backoff, CachePadded};
 
+use maybe_uninit::MaybeUninit;
+
 use context::Context;
 use err::{RecvTimeoutError, SendTimeoutError, TryRecvError, TrySendError};
 use select::{Operation, SelectHandle, Selected, Token};

crossbeam-channel/src/flavors/list.rs

@@ -2,13 +2,14 @@
 
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
-use std::mem::MaybeUninit;
 use std::ptr;
 use std::sync::atomic::{self, AtomicPtr, AtomicUsize, Ordering};
 use std::time::Instant;
 
 use crossbeam_utils::{Backoff, CachePadded};
 
+use maybe_uninit::MaybeUninit;
+
 use context::Context;
 use err::{RecvTimeoutError, SendTimeoutError, TryRecvError, TrySendError};
 use select::{Operation, SelectHandle, Selected, Token};

crossbeam-channel/src/lib.rs

@@ -348,6 +348,7 @@
 #![warn(missing_debug_implementations)]
 
 extern crate crossbeam_utils;
+extern crate maybe_uninit;
 
 mod channel;
 mod context;

crossbeam-deque/Cargo.toml

@@ -15,6 +15,9 @@ description = "Concurrent work-stealing deque"
 keywords = ["chase-lev", "lock-free", "scheduler", "scheduling"]
 categories = ["algorithms", "concurrency", "data-structures"]
 
+[dependencies]
+maybe-uninit = "2.0.0"
+
 [dependencies.crossbeam-epoch]
 version = "0.8"
 path = "../crossbeam-epoch"

crossbeam-deque/src/lib.rs

@@ -92,19 +92,23 @@
 extern crate crossbeam_epoch as epoch;
 extern crate crossbeam_utils as utils;
 
+extern crate maybe_uninit;
+
 use std::cell::{Cell, UnsafeCell};
 use std::cmp;
 use std::fmt;
 use std::iter::FromIterator;
 use std::marker::PhantomData;
-use std::mem::{self, MaybeUninit};
+use std::mem;
 use std::ptr;
 use std::sync::atomic::{self, AtomicIsize, AtomicPtr, AtomicUsize, Ordering};
 use std::sync::Arc;
 
 use epoch::{Atomic, Owned};
 use utils::{Backoff, CachePadded};
 
+use maybe_uninit::MaybeUninit;
+
 // Minimum buffer capacity.
 const MIN_CAP: usize = 64;
 // Maximum number of tasks that can be stolen in `steal_batch()` and `steal_batch_and_pop()`.

crossbeam-epoch/Cargo.toml

@@ -24,6 +24,7 @@ sanitize = [] # Makes it more likely to trigger any potential data races.
 
 [dependencies]
 cfg-if = "0.1.2"
+maybe-uninit = "2.0.0"
 memoffset = "0.5"
 
 [dependencies.crossbeam-utils]

crossbeam-epoch/src/deferred.rs

@@ -1,9 +1,11 @@
 use alloc::boxed::Box;
 use core::fmt;
 use core::marker::PhantomData;
-use core::mem::{self, MaybeUninit};
+use core::mem;
 use core::ptr;
 
+use maybe_uninit::MaybeUninit;
+
 /// Number of words a piece of `Data` can hold.
 ///
 /// Three words should be enough for the majority of cases. For example, you can fit inside it the

crossbeam-epoch/src/lib.rs

@@ -64,6 +64,8 @@ extern crate cfg_if;
 #[cfg(feature = "std")]
 extern crate core;
 
+extern crate maybe_uninit;
+
 cfg_if! {
     if #[cfg(feature = "alloc")] {
         extern crate alloc;

crossbeam-epoch/src/sync/queue.rs

@@ -8,11 +8,12 @@
 //! Simon Doherty, Lindsay Groves, Victor Luchangco, and Mark Moir. 2004b. Formal Verification of a
 //! Practical Lock-Free Queue Algorithm. https://doi.org/10.1007/978-3-540-30232-2_7
 
-use core::mem::MaybeUninit;
 use core::sync::atomic::Ordering::{Acquire, Relaxed, Release};
 
 use crossbeam_utils::CachePadded;
 
+use maybe_uninit::MaybeUninit;
+
 use {unprotected, Atomic, Guard, Owned, Shared};
 
 // The representation here is a singly-linked list, with a sentinel node at the front. In general

crossbeam-queue/Cargo.toml

@@ -22,6 +22,7 @@ alloc = ["crossbeam-utils/alloc"]
 
 [dependencies]
 cfg-if = "0.1.2"
+maybe-uninit = "2.0.0"
 
 [dependencies.crossbeam-utils]
 version = "0.7"

crossbeam-queue/src/array_queue.rs

@@ -12,12 +12,14 @@ use alloc::vec::Vec;
 use core::cell::UnsafeCell;
 use core::fmt;
 use core::marker::PhantomData;
-use core::mem::{self, MaybeUninit};
+use core::mem;
 use core::ptr;
 use core::sync::atomic::{self, AtomicUsize, Ordering};
 
 use crossbeam_utils::{Backoff, CachePadded};
 
+use maybe_uninit::MaybeUninit;
+
 use err::{PopError, PushError};
 
 /// A slot in a queue.

crossbeam-queue/src/lib.rs

@@ -17,6 +17,8 @@ extern crate cfg_if;
 #[cfg(feature = "std")]
 extern crate core;
 
+extern crate maybe_uninit;
+
 cfg_if! {
     if #[cfg(feature = "alloc")] {
         extern crate alloc;

crossbeam-queue/src/seg_queue.rs

@@ -2,12 +2,13 @@ use alloc::boxed::Box;
 use core::cell::UnsafeCell;
 use core::fmt;
 use core::marker::PhantomData;
-use core::mem::MaybeUninit;
 use core::ptr;
 use core::sync::atomic::{self, AtomicPtr, AtomicUsize, Ordering};
 
 use crossbeam_utils::{Backoff, CachePadded};
 
+use maybe_uninit::MaybeUninit;
+
 use err::PopError;
 
 // Bits indicating the state of a slot: