From 833b2b43eef0af7e05106bf6618c036dee737a88 Mon Sep 17 00:00:00 2001
From: sb123sb123 <152394158+sb123sb123@users.noreply.github.com>
Date: Tue, 22 Sep 2026 08:30:14 +0800
Subject: [PATCH 1/3] Implement From<Arc<[u8]>> for Bytes

---
 src/bytes.rs        | 10 ++++++++++
 tests/test_bytes.rs | 11 +++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/bytes.rs b/src/bytes.rs
index aed4d7cdb..f693ff9aa 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -11,6 +11,9 @@ use alloc::{
     vec::Vec,
 };
 
+#[cfg(target_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(target_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`.
     ///
diff --git a/tests/test_bytes.rs b/tests/test_bytes.rs
index 5d01b5b82..c0440290b 100644
--- a/tests/test_bytes.rs
+++ b/tests/test_bytes.rs
@@ -67,6 +67,17 @@ fn from_slice() {
     assert_eq!(Vec::from(&b"abcdefgh"[..]), a);
 }
 
+#[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"[..]));

From ca93cf66e873f78c5c2dae1250e4c47db777f497 Mon Sep 17 00:00:00 2001
From: NekoPaw <152394158+sb123sb123@users.noreply.github.com>
Date: Tue, 29 Sep 2026 17:04:50 +0800
Subject: [PATCH 2/3] test: gate Arc conversion on pointer atomics

---
 tests/test_bytes.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_bytes.rs b/tests/test_bytes.rs
index c0440290b..2050d9273 100644
--- a/tests/test_bytes.rs
+++ b/tests/test_bytes.rs
@@ -67,6 +67,7 @@ fn from_slice() {
     assert_eq!(Vec::from(&b"abcdefgh"[..]), a);
 }
 
+#[cfg(target_has_atomic = "ptr")]
 #[test]
 fn from_arc() {
     let source: Arc<[u8]> = Arc::from(&b"abcdefgh"[..]);

From 321d3cb9f576eeb9ae7b87d07da6db14e39c5b3f Mon Sep 17 00:00:00 2001
From: NekoPaw <152394158+sb123sb123@users.noreply.github.com>
Date: Tue, 29 Sep 2026 10:09:09 +0000
Subject: [PATCH 3/3] fix: keep Arc cfg compatible with Rust 1.57

---
 build.rs            | 10 ++++++++++
 src/bytes.rs        |  4 ++--
 tests/test_bytes.rs |  2 +-
 3 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 build.rs

diff --git a/build.rs b/build.rs
new file mode 100644
index 000000000..356f97187
--- /dev/null
+++ b/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");
+    }
+}
diff --git a/src/bytes.rs b/src/bytes.rs
index f693ff9aa..86f06195d 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -11,7 +11,7 @@ use alloc::{
     vec::Vec,
 };
 
-#[cfg(target_has_atomic = "ptr")]
+#[cfg(bytes_has_atomic_ptr)]
 use alloc::sync::Arc;
 
 use crate::buf::IntoIter;
@@ -1017,7 +1017,7 @@ impl From<Box<[u8]>> for Bytes {
     }
 }
 
-#[cfg(target_has_atomic = "ptr")]
+#[cfg(bytes_has_atomic_ptr)]
 impl From<Arc<[u8]>> for Bytes {
     fn from(arc: Arc<[u8]>) -> Bytes {
         Bytes::from_owner(arc)
diff --git a/tests/test_bytes.rs b/tests/test_bytes.rs
index 2050d9273..5615d92d1 100644
--- a/tests/test_bytes.rs
+++ b/tests/test_bytes.rs
@@ -67,7 +67,7 @@ fn from_slice() {
     assert_eq!(Vec::from(&b"abcdefgh"[..]), a);
 }
 
-#[cfg(target_has_atomic = "ptr")]
+#[cfg(bytes_has_atomic_ptr)]
 #[test]
 fn from_arc() {
     let source: Arc<[u8]> = Arc::from(&b"abcdefgh"[..]);