Implement From<Arc<[u8]>> for Bytes

build.rs

@@ -0,0 +1,10 @@
+use std::env;
+
+fn main() {
+    println!("cargo:rustc-check-cfg=cfg(bytes_has_atomic_ptr)");
+
+    let target_atomics = env::var("CARGO_CFG_TARGET_HAS_ATOMIC").unwrap_or_default();
+    if target_atomics.split(',').any(|atomic| atomic == "ptr") {
+        println!("cargo:rustc-cfg=bytes_has_atomic_ptr");
+    }
+}

src/bytes.rs

@@ -11,6 +11,9 @@ use alloc::{
     vec::Vec,
 };
 
+#[cfg(bytes_has_atomic_ptr)]
+use alloc::sync::Arc;
+
 use crate::buf::IntoIter;
 #[allow(unused)]
 use crate::loom::sync::atomic::AtomicMut;
@@ -1014,6 +1017,13 @@ impl From<Box<[u8]>> for Bytes {
     }
 }
 
+#[cfg(bytes_has_atomic_ptr)]
+impl From<Arc<[u8]>> for Bytes {
+    fn from(arc: Arc<[u8]>) -> Bytes {
+        Bytes::from_owner(arc)
+    }
+}
+
 impl From<Bytes> for BytesMut {
     /// Convert self into `BytesMut`.
     ///

tests/test_bytes.rs

@@ -67,6 +67,18 @@ fn from_slice() {
     assert_eq!(Vec::from(&b"abcdefgh"[..]), a);
 }
 
+#[cfg(bytes_has_atomic_ptr)]
+#[test]
+fn from_arc() {
+    let source: Arc<[u8]> = Arc::from(&b"abcdefgh"[..]);
+    let source_ptr = source.as_ptr();
+    let bytes = Bytes::from(source.clone());
+    drop(source);
+
+    assert_eq!(bytes, b"abcdefgh"[..]);
+    assert_eq!(bytes.as_ptr(), source_ptr);
+}
+
 #[test]
 fn fmt() {
     let a = format!("{:?}", Bytes::from(&b"abcdefg"[..]));