Upgrade crossbeam-utils to 0.8.19 am: 6e8d2d5a50emu-34-2-dev

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/crossbeam-utils/+/2943531

Change-Id: I813bf8df4bbece4f9e239e30caa5977972318b9a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 19 insertions, 24 deletions

diff --git a/src/atomic/mod.rs b/src/atomic/mod.rs
index 3896785..7b39fe4 100644
--- a/src/atomic/mod.rs
+++ b/src/atomic/mod.rs
@@ -3,35 +3,30 @@
 //! * [`AtomicCell`], a thread-safe mutable memory location.
 //! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
 
-#[cfg(not(crossbeam_no_atomic_cas))]
+#[cfg(target_has_atomic = "ptr")]
 #[cfg(not(crossbeam_loom))]
-cfg_if::cfg_if! {
-    // Use "wide" sequence lock if the pointer width <= 32 for preventing its counter against wrap
-    // around.
-    //
-    // We are ignoring too wide architectures (pointer width >= 256), since such a system will not
-    // appear in a conceivable future.
-    //
-    // In narrow architectures (pointer width <= 16), the counter is still <= 32-bit and may be
-    // vulnerable to wrap around. But it's mostly okay, since in such a primitive hardware, the
-    // counter will not be increased that fast.
-    if #[cfg(any(target_pointer_width = "64", target_pointer_width = "128"))] {
-        mod seq_lock;
-    } else {
-        #[path = "seq_lock_wide.rs"]
-        mod seq_lock;
-    }
-}
+// Use "wide" sequence lock if the pointer width <= 32 for preventing its counter against wrap
+// around.
+//
+// In narrow architectures (pointer width <= 16), the counter is still <= 32-bit and may be
+// vulnerable to wrap around. But it's mostly okay, since in such a primitive hardware, the
+// counter will not be increased that fast.
+// Note that Rust (and C99) pointers must be at least 16-bits: https://github.com/rust-lang/rust/pull/49305
+#[cfg_attr(
+    any(target_pointer_width = "16", target_pointer_width = "32"),
+    path = "seq_lock_wide.rs"
+)]
+mod seq_lock;
 
-#[cfg(not(crossbeam_no_atomic_cas))]
+#[cfg(target_has_atomic = "ptr")]
 // We cannot provide AtomicCell under cfg(crossbeam_loom) because loom's atomic
 // types have a different in-memory representation than the underlying type.
 // TODO: The latest loom supports fences, so fallback using seqlock may be available.
 #[cfg(not(crossbeam_loom))]
 mod atomic_cell;
-mod consume;
-
-#[cfg(not(crossbeam_no_atomic_cas))]
+#[cfg(target_has_atomic = "ptr")]
 #[cfg(not(crossbeam_loom))]
-pub use self::atomic_cell::AtomicCell;
-pub use self::consume::AtomicConsume;
+pub use atomic_cell::AtomicCell;
+
+mod consume;
+pub use consume::AtomicConsume;