From 449e5d7b2d57ca101e364a0596e84c792a78d674 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Mon, 23 Sep 2024 05:58:38 +0900
Subject: [PATCH] Add portable-atomic feature and disable
 portable-atomic/critical-section by default

---
 Cargo.lock.msrv |  3 ---
 Cargo.toml      | 14 ++++++++++----
 src/race.rs     |  4 ++--
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock.msrv b/Cargo.lock.msrv
index e2b0243..9da533e 100644
--- a/Cargo.lock.msrv
+++ b/Cargo.lock.msrv
@@ -69,9 +69,6 @@ name = "portable-atomic"
 version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "da544ee218f0d287a911e9c99a39a8c9bc8fcad3cb8db5959940044ecfc67265"
-dependencies = [
- "critical-section",
-]
 
 [[package]]
 name = "redox_syscall"
diff --git a/Cargo.toml b/Cargo.toml
index e59b414..54954f6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,7 +21,7 @@ members = ["xtask"]
 
 [dependencies]
 parking_lot_core = { version = "0.9.10", optional = true, default-features = false }
-portable-atomic = { version = "1.7", optional = true }
+portable-atomic = { version = "1.7", optional = true, default-features = false }
 critical-section = { version = "1.1.3", optional = true }
 
 [dev-dependencies]
@@ -38,17 +38,23 @@ std = ["alloc"]
 alloc = ["race"]
 
 # Enables `once_cell::race` module.
-race = []
+race = ["portable-atomic?/require-cas"]
 
 # Uses parking_lot to implement once_cell::sync::OnceCell.
 # This makes no speed difference, but makes each OnceCell<T>
 # up to 16 bytes smaller, depending on the size of the T.
 parking_lot = ["dep:parking_lot_core"]
 
-# Uses `critical-section` to implement `sync` and `race` modules. in
+# Uses `portable-atomic` to implement `race` module. in
+# `#![no_std]` mode. Please read `portable-atomic` docs carefully
+# before enabling this feature.
+portable-atomic = ["dep:portable-atomic"]
+
+# Uses `critical-section` to implement `sync` module. in
 # `#![no_std]` mode. Please read `critical-section` docs carefully
 # before enabling this feature.
-critical-section = ["dep:critical-section", "portable-atomic/critical-section"]
+# `portable-atomic` feature is enabled for backwards compatibility.
+critical-section = ["dep:critical-section", "portable-atomic"]
 
 # Enables semver-exempt APIs of this crate.
 # At the moment, this feature is unused.
diff --git a/src/race.rs b/src/race.rs
index 89e4367..9c09323 100644
--- a/src/race.rs
+++ b/src/race.rs
@@ -19,9 +19,9 @@
 //! `Acquire` and `Release` have very little performance overhead on most
 //! architectures versus `Relaxed`.
 
-#[cfg(not(feature = "critical-section"))]
+#[cfg(not(feature = "portable-atomic"))]
 use core::sync::atomic;
-#[cfg(feature = "critical-section")]
+#[cfg(feature = "portable-atomic")]
 use portable_atomic as atomic;
 
 use atomic::{AtomicPtr, AtomicUsize, Ordering};