Snap for 8188146 from 746ceecf7cf7cd97801582f876a68ba474fe6e95 to tm-frc-media-release

Change-Id: Ia8c0d4374b67da3a4670a00b32195b368f9ea95e

14 files changed, 118 insertions, 204 deletions

diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 1f53d5d..1d9c34d 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "6d4cdd4daf9a897deef6cde9569f2fbf12c29bc5"
+    "sha1": "d841a2028dc72b4e09739116f07e865db60f3690"
   }
 }
diff --git a/Android.bp b/Android.bp
index 1ded857..bba5b1e 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,4 @@
-// This file is generated by cargo2android.py --config cargo2android.json.
+// This file is generated by cargo2android.py --run --device --dependencies --tests.
 // Do not modify this file as changes will be overridden on upgrade.
 
 package {
@@ -39,18 +39,48 @@ license {
     ],
 }
 
-rust_test {
-    name: "crossbeam-epoch_test_src_lib",
-    host_supported: true,
+rust_defaults {
+    name: "crossbeam-epoch_defaults",
     crate_name: "crossbeam_epoch",
-    cargo_env_compat: true,
-    cargo_pkg_version: "0.9.5",
     srcs: ["src/lib.rs"],
     test_suites: ["general-tests"],
     auto_gen_config: true,
+    edition: "2018",
+    features: [
+        "alloc",
+        "default",
+        "lazy_static",
+        "std",
+    ],
+    rustlibs: [
+        "libcfg_if",
+        "libcrossbeam_utils",
+        "liblazy_static",
+        "libmemoffset",
+        "librand",
+        "libscopeguard",
+    ],
+}
+
+rust_test_host {
+    name: "crossbeam-epoch_host_test_src_lib",
+    defaults: ["crossbeam-epoch_defaults"],
     test_options: {
         unit_test: true,
     },
+}
+
+rust_test {
+    name: "crossbeam-epoch_device_test_src_lib",
+    defaults: ["crossbeam-epoch_defaults"],
+}
+
+rust_defaults {
+    name: "crossbeam-epoch_defaults_loom",
+    crate_name: "loom",
+    srcs: ["tests/loom.rs"],
+    test_suites: ["general-tests"],
+    auto_gen_config: true,
     edition: "2018",
     features: [
         "alloc",
@@ -60,6 +90,7 @@ rust_test {
     ],
     rustlibs: [
         "libcfg_if",
+        "libcrossbeam_epoch",
         "libcrossbeam_utils",
         "liblazy_static",
         "libmemoffset",
@@ -68,12 +99,23 @@ rust_test {
     ],
 }
 
+rust_test_host {
+    name: "crossbeam-epoch_host_test_tests_loom",
+    defaults: ["crossbeam-epoch_defaults_loom"],
+    test_options: {
+        unit_test: true,
+    },
+}
+
+rust_test {
+    name: "crossbeam-epoch_device_test_tests_loom",
+    defaults: ["crossbeam-epoch_defaults_loom"],
+}
+
 rust_library {
     name: "libcrossbeam_epoch",
     host_supported: true,
     crate_name: "crossbeam_epoch",
-    cargo_env_compat: true,
-    cargo_pkg_version: "0.9.5",
     srcs: ["src/lib.rs"],
     edition: "2018",
     features: [
@@ -90,3 +132,17 @@ rust_library {
         "libscopeguard",
     ],
 }
+
+// dependent_library ["feature_list"]
+//   autocfg-1.0.1
+//   cfg-if-1.0.0
+//   crossbeam-utils-0.8.3 "lazy_static,std"
+//   getrandom-0.2.2 "std"
+//   lazy_static-1.4.0
+//   libc-0.2.92
+//   memoffset-0.6.3 "default"
+//   ppv-lite86-0.2.10 "simd,std"
+//   rand-0.8.3 "alloc,default,getrandom,libc,rand_chacha,rand_hc,std,std_rng"
+//   rand_chacha-0.3.0 "std"
+//   rand_core-0.6.2 "alloc,getrandom,std"
+//   scopeguard-1.1.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c78fbf8..0f30b70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,14 +1,3 @@
-# Version 0.9.5
-
-- Fix UB in `Pointable` impl of `[MaybeUninit<T>]` (#694)
-- Support targets that do not have atomic CAS on stable Rust (#698)
-- Fix breakage with nightly feature due to rust-lang/rust#84510 (#692)
-
-# Version 0.9.4
-
-- Fix UB in `<[MaybeUninit<T>] as Pointable>::init` when global allocator failed allocation (#690)
-- Bump `loom` dependency to version 0.5. (#686)
-
 # Version 0.9.3
 
 - Make `loom` dependency optional. (#666)
diff --git a/Cargo.lock b/Cargo.lock
index 596c26d..fd37e90 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -10,9 +10,9 @@ checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
 
 [[package]]
 name = "cc"
-version = "1.0.68"
+version = "1.0.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4a72c244c1ff497a746a7e1fb3d14bd08420ecda70c8f25c7112f2781652d787"
+checksum = "e3c69b077ad434294d3ce9f1f6143a2a4b89a8a2d54ef813d85003a4fd1137fd"
 
 [[package]]
 name = "cfg-if"
@@ -22,13 +22,13 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "const_fn"
-version = "0.4.8"
+version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f92cfa0fd5690b3cf8c1ef2cabbd9b7ef22fa53cf5e1f92b05103f6d5d1cf6e7"
+checksum = "28b9d6de7f49e22cf97ad17fc4036ece69300032f45f78f30b4a4482cdc3f4a6"
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.5"
+version = "0.9.3"
 dependencies = [
  "cfg-if",
  "const_fn",
@@ -42,10 +42,11 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.5"
+version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d82cfc11ce7f2c3faef78d8a684447b40d503d9681acebed6cb728d45940c4db"
+checksum = "e7e9d99fa91428effe99c5c6d4634cdeba32b8cf784fc428a2a687f61a952c49"
 dependencies = [
+ "autocfg",
  "cfg-if",
  "lazy_static",
  "loom",
@@ -53,9 +54,9 @@ dependencies = [
 
 [[package]]
 name = "generator"
-version = "0.7.0"
+version = "0.6.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1d9279ca822891c1a4dae06d185612cf8fc6acfe5dff37781b41297811b12ee"
+checksum = "a9fed24fd1e18827652b4d55652899a1e9da8e54d91624dc3437a5bc3a9f9a9c"
 dependencies = [
  "cc",
  "libc",
@@ -66,9 +67,9 @@ dependencies = [
 
 [[package]]
 name = "getrandom"
-version = "0.2.3"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
+checksum = "c9495705279e7140bf035dde1f6e750c162df8b625267cd52cc44e0b156732c8"
 dependencies = [
  "cfg-if",
  "libc",
@@ -83,9 +84,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.95"
+version = "0.2.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "789da6d93f1b866ffe175afc5322a4d76c038605a1c3319bb57b06967ca98a36"
+checksum = "b7282d924be3275cec7f6756ff4121987bc6481325397dde6ba3e7802b1a8b1c"
 
 [[package]]
 name = "log"
@@ -98,9 +99,9 @@ dependencies = [
 
 [[package]]
 name = "loom"
-version = "0.5.0"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7aa5348dc45fa5f2419b6dd4ea20345e6b01b1fcc9d176a322eada1ac3f382ba"
+checksum = "d44c73b4636e497b4917eb21c33539efa3816741a2d3ff26c6316f1b529481a4"
 dependencies = [
  "cfg-if",
  "generator",
@@ -109,9 +110,9 @@ dependencies = [
 
 [[package]]
 name = "memoffset"
-version = "0.6.4"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59accc507f1338036a0477ef61afdae33cde60840f4dfe481319ce3ad116ddf9"
+checksum = "157b4208e3059a8f9e78d559edc658e13df41410cb3ae03979c83130067fdd87"
 dependencies = [
  "autocfg",
 ]
@@ -164,9 +165,9 @@ dependencies = [
 
 [[package]]
 name = "rustversion"
-version = "1.0.5"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61b3909d758bb75c79f23d4736fac9433868679d3ad2ea7a61e3c25cfda9a088"
+checksum = "cb5d2a036dc6d2d8fd16fde3498b04306e29bd193bf306a57427019b823d5acd"
 
 [[package]]
 name = "scoped-tls"
diff --git a/Cargo.toml b/Cargo.toml
index 97f3df3..2d7eb00 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@
 [package]
 edition = "2018"
 name = "crossbeam-epoch"
-version = "0.9.5"
+version = "0.9.3"
 authors = ["The Crossbeam Project Developers"]
 description = "Epoch-based garbage collection"
 homepage = "https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-epoch"
@@ -30,7 +30,7 @@ version = "0.4.4"
 optional = true
 
 [dependencies.crossbeam-utils]
-version = "0.8.5"
+version = "0.8.3"
 default-features = false
 
 [dependencies.lazy_static]
@@ -53,6 +53,6 @@ loom = ["loom-crate", "crossbeam-utils/loom"]
 nightly = ["crossbeam-utils/nightly", "const_fn"]
 std = ["alloc", "crossbeam-utils/std", "lazy_static"]
 [target."cfg(crossbeam_loom)".dependencies.loom-crate]
-version = "0.5"
+version = "0.4"
 optional = true
 package = "loom"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 939e346..8961f25 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -4,7 +4,7 @@ name = "crossbeam-epoch"
 # - Update CHANGELOG.md
 # - Update README.md
 # - Create "crossbeam-epoch-X.Y.Z" git tag
-version = "0.9.5"
+version = "0.9.3"
 authors = ["The Crossbeam Project Developers"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -24,21 +24,18 @@ std = ["alloc", "crossbeam-utils/std", "lazy_static"]
 
 # Enable to use APIs that require `alloc`.
 # This is enabled by default and also enabled if the `std` feature is enabled.
-#
-# NOTE: Disabling both `std` *and* `alloc` features is not supported yet.
 alloc = []
 
 # Enable to use of unstable functionality.
 # This is disabled by default and requires recent nightly compiler.
-#
-# NOTE: This feature is outside of the normal semver guarantees and minor or
-# patch versions of crossbeam may make breaking changes to them at any time.
+# Note that this is outside of the normal semver guarantees and minor versions
+# of crossbeam may make breaking changes to them at any time.
 nightly = ["crossbeam-utils/nightly", "const_fn"]
 
 # Enable the use of loom for concurrency testing.
 #
-# NOTE: This feature is outside of the normal semver guarantees and minor or
-# patch versions of crossbeam may make breaking changes to them at any time.
+# This configuration option is outside of the normal semver guarantees: minor
+# versions of crossbeam may make breaking changes to it at any time.
 loom = ["loom-crate", "crossbeam-utils/loom"]
 
 [dependencies]
@@ -48,13 +45,13 @@ memoffset = "0.6"
 
 # Enable the use of loom for concurrency testing.
 #
-# NOTE: This feature is outside of the normal semver guarantees and minor or
-# patch versions of crossbeam may make breaking changes to them at any time.
+# This configuration option is outside of the normal semver guarantees: minor
+# versions of crossbeam may make breaking changes to it at any time.
 [target.'cfg(crossbeam_loom)'.dependencies]
-loom-crate = { package = "loom", version = "0.5", optional = true }
+loom-crate = { package = "loom", version = "0.4", optional = true }
 
 [dependencies.crossbeam-utils]
-version = "0.8.5"
+version = "0.8.3"
 path = "../crossbeam-utils"
 default-features = false
 
diff --git a/METADATA b/METADATA
index 626ee8f..fc37c40 100644
--- a/METADATA
+++ b/METADATA
@@ -7,13 +7,13 @@ third_party {
   }
   url {
     type: ARCHIVE
-    value: "https://static.crates.io/crates/crossbeam-epoch/crossbeam-epoch-0.9.5.crate"
+    value: "https://static.crates.io/crates/crossbeam-epoch/crossbeam-epoch-0.9.3.crate"
   }
-  version: "0.9.5"
+  version: "0.9.3"
   license_type: NOTICE
   last_upgrade_date {
     year: 2021
-    month: 6
-    day: 21
+    month: 4
+    day: 1
   }
 }
diff --git a/README.md b/README.md
index eb33bad..c8ebd87 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ https://crates.io/crates/crossbeam-epoch)
 https://docs.rs/crossbeam-epoch)
 [![Rust 1.36+](https://img.shields.io/badge/rust-1.36+-lightgray.svg)](
 https://www.rust-lang.org)
-[![chat](https://img.shields.io/discord/569610676205781012.svg?logo=discord)](https://discord.com/invite/JXYwgWZ)
+[![chat](https://img.shields.io/discord/569610676205781012.svg?logo=discord)](https://discord.gg/BBYwKq)
 
 This crate provides epoch-based garbage collection for building concurrent data structures.
 
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 161921c..25a9cdc 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -1,30 +1,8 @@
 // Generated by update_crate_tests.py for tests that depend on this crate.
 {
-  "imports": [
-    {
-      "path": "external/rust/crates/base64"
-    },
-    {
-      "path": "external/rust/crates/crossbeam-deque"
-    },
-    {
-      "path": "external/rust/crates/tinytemplate"
-    },
-    {
-      "path": "external/rust/crates/tinyvec"
-    },
-    {
-      "path": "external/rust/crates/unicode-xid"
-    }
-  ],
   "presubmit": [
     {
-      "name": "crossbeam-epoch_test_src_lib"
-    }
-  ],
-  "presubmit-rust": [
-    {
-      "name": "crossbeam-epoch_test_src_lib"
+      "name": "crossbeam-epoch_device_test_src_lib"
     }
   ]
 }
diff --git a/build.rs b/build.rs
deleted file mode 100644
index 4ef1279..0000000
--- a/build.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-#![warn(rust_2018_idioms)]
-
-use std::env;
-
-include!("no_atomic.rs");
-
-// The rustc-cfg strings below are *not* public API. Please let us know by
-// opening a GitHub issue if your build environment requires some way to enable
-// these cfgs other than by executing our build script.
-fn main() {
-    let target = match env::var("TARGET") {
-        Ok(target) => target,
-        Err(e) => {
-            println!(
-                "cargo:warning={}: unable to get TARGET environment variable: {}",
-                env!("CARGO_PKG_NAME"),
-                e
-            );
-            return;
-        }
-    };
-
-    // Note that this is `no_*`, not `has_*`. This allows treating
-    // `cfg(target_has_atomic = "ptr")` as true when the build script doesn't
-    // run. This is needed for compatibility with non-cargo build systems that
-    // don't run the build script.
-    if NO_ATOMIC_CAS.contains(&&*target) {
-        println!("cargo:rustc-cfg=crossbeam_no_atomic_cas");
-    }
-
-    println!("cargo:rerun-if-changed=no_atomic.rs");
-}
diff --git a/cargo2android.json b/cargo2android.json
deleted file mode 100644
index d36fb44..0000000
--- a/cargo2android.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "device": true,
-  "run": true,
-  "tests": true
-}
\ No newline at end of file
diff --git a/no_atomic.rs b/no_atomic.rs
deleted file mode 100644
index 522b3b8..0000000
--- a/no_atomic.rs
+++ /dev/null
@@ -1,59 +0,0 @@
-// This file is @generated by no_atomic.sh.
-// It is not intended for manual editing.
-
-const NO_ATOMIC_CAS: &[&str] = &[
-    "avr-unknown-gnu-atmega328",
-    "msp430-none-elf",
-    "riscv32i-unknown-none-elf",
-    "riscv32imc-unknown-none-elf",
-    "thumbv4t-none-eabi",
-    "thumbv6m-none-eabi",
-];
-#[allow(dead_code)]
-const NO_ATOMIC_64: &[&str] = &[
-    "arm-linux-androideabi",
-    "armebv7r-none-eabi",
-    "armebv7r-none-eabihf",
-    "armv4t-unknown-linux-gnueabi",
-    "armv5te-unknown-linux-gnueabi",
-    "armv5te-unknown-linux-musleabi",
-    "armv5te-unknown-linux-uclibceabi",
-    "armv7r-none-eabi",
-    "armv7r-none-eabihf",
-    "hexagon-unknown-linux-musl",
-    "mips-unknown-linux-gnu",
-    "mips-unknown-linux-musl",
-    "mips-unknown-linux-uclibc",
-    "mipsel-unknown-linux-gnu",
-    "mipsel-unknown-linux-musl",
-    "mipsel-unknown-linux-uclibc",
-    "mipsel-unknown-none",
-    "mipsisa32r6-unknown-linux-gnu",
-    "mipsisa32r6el-unknown-linux-gnu",
-    "powerpc-unknown-linux-gnu",
-    "powerpc-unknown-linux-gnuspe",
-    "powerpc-unknown-linux-musl",
-    "powerpc-unknown-netbsd",
-    "powerpc-unknown-openbsd",
-    "powerpc-wrs-vxworks",
-    "powerpc-wrs-vxworks-spe",
-    "riscv32gc-unknown-linux-gnu",
-    "riscv32gc-unknown-linux-musl",
-    "riscv32imac-unknown-none-elf",
-    "thumbv7em-none-eabi",
-    "thumbv7em-none-eabihf",
-    "thumbv7m-none-eabi",
-    "thumbv8m.base-none-eabi",
-    "thumbv8m.main-none-eabi",
-    "thumbv8m.main-none-eabihf",
-    "mipsel-sony-psp",
-    "thumbv4t-none-eabi",
-    "thumbv6m-none-eabi",
-];
-#[allow(dead_code)]
-const NO_ATOMIC: &[&str] = &[
-    "avr-unknown-gnu-atmega328",
-    "msp430-none-elf",
-    "riscv32i-unknown-none-elf",
-    "riscv32imc-unknown-none-elf",
-];
diff --git a/src/atomic.rs b/src/atomic.rs
index adb0afa..e4ca23f 100644
--- a/src/atomic.rs
+++ b/src/atomic.rs
@@ -238,8 +238,7 @@ impl<T> Pointable for T {
 // [`alloc::alloc::Layout::extend`] instead.
 #[repr(C)]
 struct Array<T> {
-    /// The number of elements (not the number of bytes).
-    len: usize,
+    size: usize,
     elements: [MaybeUninit<T>; 0],
 }
 
@@ -248,31 +247,28 @@ impl<T> Pointable for [MaybeUninit<T>] {
 
     type Init = usize;
 
-    unsafe fn init(len: Self::Init) -> usize {
-        let size = mem::size_of::<Array<T>>() + mem::size_of::<MaybeUninit<T>>() * len;
+    unsafe fn init(size: Self::Init) -> usize {
+        let size = mem::size_of::<Array<T>>() + mem::size_of::<MaybeUninit<T>>() * size;
         let align = mem::align_of::<Array<T>>();
         let layout = alloc::Layout::from_size_align(size, align).unwrap();
         let ptr = alloc::alloc(layout) as *mut Array<T>;
-        if ptr.is_null() {
-            alloc::handle_alloc_error(layout);
-        }
-        (*ptr).len = len;
+        (*ptr).size = size;
         ptr as usize
     }
 
     unsafe fn deref<'a>(ptr: usize) -> &'a Self {
         let array = &*(ptr as *const Array<T>);
-        slice::from_raw_parts(array.elements.as_ptr() as *const _, array.len)
+        slice::from_raw_parts(array.elements.as_ptr() as *const _, array.size)
     }
 
     unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut Self {
         let array = &*(ptr as *mut Array<T>);
-        slice::from_raw_parts_mut(array.elements.as_ptr() as *mut _, array.len)
+        slice::from_raw_parts_mut(array.elements.as_ptr() as *mut _, array.size)
     }
 
     unsafe fn drop(ptr: usize) {
         let array = &*(ptr as *mut Array<T>);
-        let size = mem::size_of::<Array<T>>() + mem::size_of::<MaybeUninit<T>>() * array.len;
+        let size = mem::size_of::<Array<T>>() + mem::size_of::<MaybeUninit<T>>() * array.size;
         let align = mem::align_of::<Array<T>>();
         let layout = alloc::Layout::from_size_align(size, align).unwrap();
         alloc::dealloc(ptr as *mut u8, layout);
@@ -1530,8 +1526,7 @@ impl<T: ?Sized + Pointable> Default for Shared<'_, T> {
 
 #[cfg(all(test, not(crossbeam_loom)))]
 mod tests {
-    use super::{Owned, Shared};
-    use std::mem::MaybeUninit;
+    use super::Shared;
 
     #[test]
     fn valid_tag_i8() {
@@ -1547,13 +1542,6 @@ mod tests {
     #[test]
     fn const_atomic_null() {
         use super::Atomic;
-        static _U: Atomic<u8> = Atomic::<u8>::null();
-    }
-
-    #[test]
-    fn array_init() {
-        let owned = Owned::<[MaybeUninit<usize>]>::init(10);
-        let arr: &[MaybeUninit<usize>] = &*owned;
-        assert_eq!(arr.len(), 10);
+        const _: Atomic<u8> = Atomic::<u8>::null();
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index ba1d331..99da911 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -62,7 +62,8 @@
     unreachable_pub
 )]
 #![cfg_attr(not(feature = "std"), no_std)]
-#![cfg_attr(feature = "nightly", feature(const_fn_trait_bound))]
+#![cfg_attr(feature = "nightly", feature(cfg_target_has_atomic))]
+#![cfg_attr(feature = "nightly", feature(const_fn))]
 
 #[cfg(crossbeam_loom)]
 extern crate loom_crate as loom;
@@ -104,11 +105,10 @@ mod primitive {
     pub(crate) use loom::lazy_static;
     pub(crate) use loom::thread_local;
 }
-#[cfg(not(crossbeam_no_atomic_cas))]
 #[cfg(not(crossbeam_loom))]
 #[allow(unused_imports, dead_code)]
 mod primitive {
-    #[cfg(feature = "alloc")]
+    #[cfg(any(feature = "alloc", feature = "std"))]
     pub(crate) mod cell {
         #[derive(Debug)]
         #[repr(transparent)]
@@ -136,13 +136,14 @@ mod primitive {
             }
         }
     }
-    #[cfg(feature = "alloc")]
+    #[cfg(any(feature = "alloc", feature = "std"))]
     pub(crate) mod sync {
         pub(crate) mod atomic {
             pub(crate) use core::sync::atomic::compiler_fence;
             pub(crate) use core::sync::atomic::fence;
             pub(crate) use core::sync::atomic::AtomicUsize;
         }
+        #[cfg_attr(feature = "nightly", cfg(target_has_atomic = "ptr"))]
         pub(crate) use alloc::sync::Arc;
     }
 
@@ -153,7 +154,7 @@ mod primitive {
     pub(crate) use lazy_static::lazy_static;
 }
 
-#[cfg(not(crossbeam_no_atomic_cas))]
+#[cfg_attr(feature = "nightly", cfg(target_has_atomic = "ptr"))]
 cfg_if! {
     if #[cfg(feature = "alloc")] {
         extern crate alloc;