use portable-atomic instead

Cargo.toml

@@ -20,8 +20,8 @@ categories = ["asynchronous", "concurrency"]
 exclude = ["/.*"]
 
 [dependencies]
-# Uses user-provided critical sections on targets without atomics.
-atomic-polyfill = { version = "1", optional = true }
+# Uses portable-atomic polyfill atomics on targets without them 
+portable-atomic = { version = "0.3", optional = true }
 
 [dev-dependencies]
 futures = "0.3.5"

src/lib.rs

@@ -17,9 +17,9 @@ use core::fmt;
 use core::sync::atomic::Ordering::{AcqRel, Acquire, Release};
 use core::task::Waker;
 
-#[cfg(feature = "atomic-polyfill")]
-use atomic_polyfill::AtomicUsize;
-#[cfg(not(feature = "atomic-polyfill"))]
+#[cfg(feature = "portable-atomic")]
+use portable_atomic::AtomicUsize;
+#[cfg(not(feature = "portable-atomic"))]
 use core::sync::atomic::AtomicUsize;
 
 /// A synchronization primitive for task wakeup.