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diff --git a/third_party/rust/crossbeam-utils/src/lib.rs b/third_party/rust/crossbeam-utils/src/lib.rs
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+//! Miscellaneous tools for concurrent programming.
+//!
+//! ## Atomics
+//!
+//! * [`AtomicCell`], a thread-safe mutable memory location.
+//! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
+//!
+//! ## Thread synchronization
+//!
+//! * [`Parker`], a thread parking primitive.
+//! * [`ShardedLock`], a sharded reader-writer lock with fast concurrent reads.
+//! * [`WaitGroup`], for synchronizing the beginning or end of some computation.
+//!
+//! ## Utilities
+//!
+//! * [`Backoff`], for exponential backoff in spin loops.
+//! * [`CachePadded`], for padding and aligning a value to the length of a cache line.
+//! * [`scope`], for spawning threads that borrow local variables from the stack.
+//!
+//! [`AtomicCell`]: atomic::AtomicCell
+//! [`AtomicConsume`]: atomic::AtomicConsume
+//! [`Parker`]: sync::Parker
+//! [`ShardedLock`]: sync::ShardedLock
+//! [`WaitGroup`]: sync::WaitGroup
+//! [`scope`]: thread::scope
+
+#![doc(test(
+    no_crate_inject,
+    attr(
+        deny(warnings, rust_2018_idioms),
+        allow(dead_code, unused_assignments, unused_variables)
+    )
+))]
+#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(feature = "nightly", feature(cfg_target_has_atomic))]
+// matches! requires Rust 1.42
+#![allow(clippy::match_like_matches_macro)]
+
+#[cfg_attr(feature = "nightly", cfg(target_has_atomic = "ptr"))]
+pub mod atomic;
+
+mod cache_padded;
+pub use crate::cache_padded::CachePadded;
+
+mod backoff;
+pub use crate::backoff::Backoff;
+
+use cfg_if::cfg_if;
+
+cfg_if! {
+    if #[cfg(feature = "std")] {
+        pub mod sync;
+        pub mod thread;
+    }
+}