Upgrade rust/crates/crossbeam-utils to 0.8.5 am: 2ce91674eb

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/crossbeam-utils/+/1742398

Change-Id: I155201329f19e8637968f22131bd877fb9ff4353

16 files changed, 231 insertions, 126 deletions

diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 78aaf0a..1f53d5d 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "d4f6785c9be365832eecfc04222f95a1c2dd314a"
+    "sha1": "6d4cdd4daf9a897deef6cde9569f2fbf12c29bc5"
   }
 }
diff --git a/Android.bp b/Android.bp
index 8fdf39b..3957788 100644
--- a/Android.bp
+++ b/Android.bp
@@ -51,12 +51,6 @@ rust_defaults {
         "lazy_static",
         "std",
     ],
-    cfgs: [
-        "has_atomic_u16",
-        "has_atomic_u32",
-        "has_atomic_u64",
-        "has_atomic_u8",
-    ],
     rustlibs: [
         "libcfg_if",
         "liblazy_static",
@@ -88,12 +82,6 @@ rust_defaults {
         "lazy_static",
         "std",
     ],
-    cfgs: [
-        "has_atomic_u16",
-        "has_atomic_u32",
-        "has_atomic_u64",
-        "has_atomic_u8",
-    ],
     rustlibs: [
         "libcfg_if",
         "libcrossbeam_utils",
@@ -203,12 +191,6 @@ rust_library {
         "lazy_static",
         "std",
     ],
-    cfgs: [
-        "has_atomic_u16",
-        "has_atomic_u32",
-        "has_atomic_u64",
-        "has_atomic_u8",
-    ],
     rustlibs: [
         "libcfg_if",
         "liblazy_static",
@@ -216,12 +198,11 @@ rust_library {
 }
 
 // dependent_library ["feature_list"]
-//   autocfg-1.0.1
 //   cfg-if-1.0.0
 //   getrandom-0.2.3 "std"
 //   lazy_static-1.4.0
-//   libc-0.2.94
+//   libc-0.2.97
 //   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"
+//   rand-0.8.4 "alloc,default,getrandom,libc,rand_chacha,rand_hc,std,std_rng"
+//   rand_chacha-0.3.1 "std"
+//   rand_core-0.6.3 "alloc,getrandom,std"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1618732..8c485ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# Version 0.8.5
+
+- Add `AtomicCell::fetch_update` (#704)
+- Support targets that do not have atomic CAS on stable Rust (#698)
+
 # Version 0.8.4
 
 - Bump `loom` dependency to version 0.5. (#686)
diff --git a/Cargo.toml b/Cargo.toml
index 65f9815..0b32b46 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@
 [package]
 edition = "2018"
 name = "crossbeam-utils"
-version = "0.8.4"
+version = "0.8.5"
 authors = ["The Crossbeam Project Developers"]
 description = "Utilities for concurrent programming"
 homepage = "https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-utils"
@@ -30,8 +30,6 @@ version = "1.4.0"
 optional = true
 [dev-dependencies.rand]
 version = "0.8"
-[build-dependencies.autocfg]
-version = "1.0.0"
 
 [features]
 default = ["std"]
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 4962b71..16488cb 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -4,7 +4,7 @@ name = "crossbeam-utils"
 # - Update CHANGELOG.md
 # - Update README.md
 # - Create "crossbeam-utils-X.Y.Z" git tag
-version = "0.8.4"
+version = "0.8.5"
 authors = ["The Crossbeam Project Developers"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -22,10 +22,13 @@ default = ["std"]
 # This is enabled by default.
 std = ["lazy_static"]
 
+# These features are no longer used.
+# TODO: remove in the next major version.
 # Enable to use of unstable functionality.
 # This is disabled by default and requires recent nightly compiler.
-# Note that this is outside of the normal semver guarantees and minor versions
-# of crossbeam may make breaking changes to them at any time.
+#
+# 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.
 nightly = []
 
 [dependencies]
@@ -34,13 +37,10 @@ lazy_static = { version = "1.4.0", optional = true }
 
 # Enable the use of loom for concurrency testing.
 #
-# This configuration option is outside of the normal semver guarantees: minor
-# versions of crossbeam may make breaking changes to it at any time.
+# 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.
 [target.'cfg(crossbeam_loom)'.dependencies]
 loom = { version = "0.5", optional = true }
 
-[build-dependencies]
-autocfg = "1.0.0"
-
 [dev-dependencies]
 rand = "0.8"
diff --git a/METADATA b/METADATA
index af54cb2..e332569 100644
--- a/METADATA
+++ b/METADATA
@@ -7,13 +7,13 @@ third_party {
   }
   url {
     type: ARCHIVE
-    value: "https://static.crates.io/crates/crossbeam-utils/crossbeam-utils-0.8.4.crate"
+    value: "https://static.crates.io/crates/crossbeam-utils/crossbeam-utils-0.8.5.crate"
   }
-  version: "0.8.4"
+  version: "0.8.5"
   license_type: NOTICE
   last_upgrade_date {
     year: 2021
-    month: 5
-    day: 20
+    month: 6
+    day: 21
   }
 }
diff --git a/TEST_MAPPING b/TEST_MAPPING
index a68b776..eea3de0 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -27,6 +27,12 @@
     },
     {
       "name": "crossbeam-utils_device_test_tests_wait_group"
+    },
+    {
+      "name": "unicode-xid_device_test_src_lib"
+    },
+    {
+      "name": "unicode-xid_device_test_tests_exhaustive_tests"
     }
   ]
 }
diff --git a/build.rs b/build.rs
index 3e51021..9c924ad 100644
--- a/build.rs
+++ b/build.rs
@@ -1,23 +1,40 @@
-use autocfg::AutoCfg;
+#![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 cfg = match AutoCfg::new() {
-        Ok(cfg) => cfg,
+    let target = match env::var("TARGET") {
+        Ok(target) => target,
         Err(e) => {
             println!(
-                "cargo:warning=crossbeam-utils: unable to determine rustc version: {}",
+                "cargo:warning={}: unable to get TARGET environment variable: {}",
+                env!("CARGO_PKG_NAME"),
                 e
             );
             return;
         }
     };
 
-    cfg.emit_type_cfg("core::sync::atomic::AtomicU8", "has_atomic_u8");
-    cfg.emit_type_cfg("core::sync::atomic::AtomicU16", "has_atomic_u16");
-    cfg.emit_type_cfg("core::sync::atomic::AtomicU32", "has_atomic_u32");
-    cfg.emit_type_cfg("core::sync::atomic::AtomicU64", "has_atomic_u64");
-    cfg.emit_type_cfg("core::sync::atomic::AtomicU128", "has_atomic_u128");
+    // 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");
+    }
+    if NO_ATOMIC.contains(&&*target) {
+        println!("cargo:rustc-cfg=crossbeam_no_atomic");
+        println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
+    } else if NO_ATOMIC_64.contains(&&*target) {
+        println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
+    } else {
+        // Otherwise, assuming `"max-atomic-width" == 64`.
+    }
+
+    println!("cargo:rerun-if-changed=no_atomic.rs");
 }
diff --git a/no_atomic.rs b/no_atomic.rs
new file mode 100644
index 0000000..522b3b8
--- /dev/null
+++ b/no_atomic.rs
@@ -0,0 +1,59 @@
+// 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/atomic_cell.rs b/src/atomic/atomic_cell.rs
index ad094b2..1a1c464 100644
--- a/src/atomic/atomic_cell.rs
+++ b/src/atomic/atomic_cell.rs
@@ -258,6 +258,40 @@ impl<T: Copy + Eq> AtomicCell<T> {
     pub fn compare_exchange(&self, current: T, new: T) -> Result<T, T> {
         unsafe { atomic_compare_exchange_weak(self.value.get(), current, new) }
     }
+
+    /// Fetches the value, and applies a function to it that returns an optional
+    /// new value. Returns a `Result` of `Ok(previous_value)` if the function returned `Some(_)`, else
+    /// `Err(previous_value)`.
+    ///
+    /// Note: This may call the function multiple times if the value has been changed from other threads in
+    /// the meantime, as long as the function returns `Some(_)`, but the function will have been applied
+    /// only once to the stored value.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use crossbeam_utils::atomic::AtomicCell;
+    ///
+    /// let a = AtomicCell::new(7);
+    /// assert_eq!(a.fetch_update(|_| None), Err(7));
+    /// assert_eq!(a.fetch_update(|a| Some(a + 1)), Ok(7));
+    /// assert_eq!(a.fetch_update(|a| Some(a + 1)), Ok(8));
+    /// assert_eq!(a.load(), 9);
+    /// ```
+    #[inline]
+    pub fn fetch_update<F>(&self, mut f: F) -> Result<T, T>
+    where
+        F: FnMut(T) -> Option<T>,
+    {
+        let mut prev = self.load();
+        while let Some(next) = f(prev) {
+            match self.compare_exchange(prev, next) {
+                x @ Ok(_) => return x,
+                Err(next_prev) => prev = next_prev,
+            }
+        }
+        Err(prev)
+    }
 }
 
 macro_rules! impl_arithmetic {
@@ -497,33 +531,25 @@ macro_rules! impl_arithmetic {
     };
 }
 
-#[cfg(has_atomic_u8)]
 impl_arithmetic!(u8, atomic::AtomicU8, "let a = AtomicCell::new(7u8);");
-#[cfg(all(has_atomic_u8, not(crossbeam_loom)))]
 impl_arithmetic!(i8, atomic::AtomicI8, "let a = AtomicCell::new(7i8);");
-#[cfg(has_atomic_u16)]
 impl_arithmetic!(u16, atomic::AtomicU16, "let a = AtomicCell::new(7u16);");
-#[cfg(all(has_atomic_u16, not(crossbeam_loom)))]
 impl_arithmetic!(i16, atomic::AtomicI16, "let a = AtomicCell::new(7i16);");
-#[cfg(has_atomic_u32)]
 impl_arithmetic!(u32, atomic::AtomicU32, "let a = AtomicCell::new(7u32);");
-#[cfg(all(has_atomic_u32, not(crossbeam_loom)))]
 impl_arithmetic!(i32, atomic::AtomicI32, "let a = AtomicCell::new(7i32);");
-#[cfg(has_atomic_u64)]
+#[cfg(not(crossbeam_no_atomic_64))]
 impl_arithmetic!(u64, atomic::AtomicU64, "let a = AtomicCell::new(7u64);");
-#[cfg(all(has_atomic_u64, not(crossbeam_loom)))]
+#[cfg(not(crossbeam_no_atomic_64))]
 impl_arithmetic!(i64, atomic::AtomicI64, "let a = AtomicCell::new(7i64);");
-#[cfg(all(has_atomic_u128, not(crossbeam_loom)))]
-impl_arithmetic!(u128, atomic::AtomicU128, "let a = AtomicCell::new(7u128);");
-#[cfg(all(has_atomic_u128, not(crossbeam_loom)))]
-impl_arithmetic!(i128, atomic::AtomicI128, "let  a = AtomicCell::new(7i128);");
+// TODO: AtomicU128 is unstable
+// impl_arithmetic!(u128, atomic::AtomicU128, "let a = AtomicCell::new(7u128);");
+// impl_arithmetic!(i128, atomic::AtomicI128, "let a = AtomicCell::new(7i128);");
 
 impl_arithmetic!(
     usize,
     atomic::AtomicUsize,
     "let a = AtomicCell::new(7usize);"
 );
-#[cfg(not(crossbeam_loom))]
 impl_arithmetic!(
     isize,
     atomic::AtomicIsize,
@@ -809,16 +835,13 @@ macro_rules! atomic {
             atomic!(@check, $t, AtomicUnit, $a, $atomic_op);
             atomic!(@check, $t, atomic::AtomicUsize, $a, $atomic_op);
 
-            #[cfg(has_atomic_u8)]
             atomic!(@check, $t, atomic::AtomicU8, $a, $atomic_op);
-            #[cfg(has_atomic_u16)]
             atomic!(@check, $t, atomic::AtomicU16, $a, $atomic_op);
-            #[cfg(has_atomic_u32)]
             atomic!(@check, $t, atomic::AtomicU32, $a, $atomic_op);
-            #[cfg(has_atomic_u64)]
+            #[cfg(not(crossbeam_no_atomic_64))]
             atomic!(@check, $t, atomic::AtomicU64, $a, $atomic_op);
-            #[cfg(has_atomic_u128)]
-            atomic!(@check, $t, atomic::AtomicU128, $a, $atomic_op);
+            // TODO: AtomicU128 is unstable
+            // atomic!(@check, $t, atomic::AtomicU128, $a, $atomic_op);
 
             #[cfg(crossbeam_loom)]
             unimplemented!("loom does not support non-atomic atomic ops");
@@ -831,17 +854,15 @@ macro_rules! atomic {
 /// Returns `true` if operations on `AtomicCell<T>` are lock-free.
 const fn atomic_is_lock_free<T>() -> bool {
     // HACK(taiki-e): This is equivalent to `atomic! { T, _a, true, false }`, but can be used in const fn even in Rust 1.36.
-    let is_lock_free = can_transmute::<T, AtomicUnit>() | can_transmute::<T, atomic::AtomicUsize>();
-    #[cfg(has_atomic_u8)]
-    let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU8>();
-    #[cfg(has_atomic_u16)]
-    let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU16>();
-    #[cfg(has_atomic_u32)]
-    let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU32>();
-    #[cfg(has_atomic_u64)]
+    let is_lock_free = can_transmute::<T, AtomicUnit>()
+        | can_transmute::<T, atomic::AtomicUsize>()
+        | can_transmute::<T, atomic::AtomicU8>()
+        | can_transmute::<T, atomic::AtomicU16>()
+        | can_transmute::<T, atomic::AtomicU32>();
+    #[cfg(not(crossbeam_no_atomic_64))]
     let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU64>();
-    #[cfg(has_atomic_u128)]
-    let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU128>();
+    // TODO: AtomicU128 is unstable
+    // let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU128>();
     is_lock_free
 }
 
diff --git a/src/atomic/consume.rs b/src/atomic/consume.rs
index 0fbd93e..277b370 100644
--- a/src/atomic/consume.rs
+++ b/src/atomic/consume.rs
@@ -1,5 +1,6 @@
 #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
 use crate::primitive::sync::atomic::compiler_fence;
+#[cfg(not(crossbeam_no_atomic))]
 use core::sync::atomic::Ordering;
 
 /// Trait which allows reading from primitive atomic types with "consume" ordering.
@@ -25,6 +26,7 @@ pub trait AtomicConsume {
     fn load_consume(&self) -> Self::Val;
 }
 
+#[cfg(not(crossbeam_no_atomic))]
 #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
 macro_rules! impl_consume {
     () => {
@@ -37,6 +39,7 @@ macro_rules! impl_consume {
     };
 }
 
+#[cfg(not(crossbeam_no_atomic))]
 #[cfg(not(any(target_arch = "arm", target_arch = "aarch64")))]
 macro_rules! impl_consume {
     () => {
@@ -49,12 +52,13 @@ macro_rules! impl_consume {
 
 macro_rules! impl_atomic {
     ($atomic:ident, $val:ty) => {
-        impl AtomicConsume for ::core::sync::atomic::$atomic {
+        #[cfg(not(crossbeam_no_atomic))]
+        impl AtomicConsume for core::sync::atomic::$atomic {
             type Val = $val;
             impl_consume!();
         }
         #[cfg(crossbeam_loom)]
-        impl AtomicConsume for ::loom::sync::atomic::$atomic {
+        impl AtomicConsume for loom::sync::atomic::$atomic {
             type Val = $val;
             impl_consume!();
         }
@@ -63,32 +67,26 @@ macro_rules! impl_atomic {
 
 impl_atomic!(AtomicBool, bool);
 impl_atomic!(AtomicUsize, usize);
-#[cfg(not(crossbeam_loom))]
 impl_atomic!(AtomicIsize, isize);
-#[cfg(has_atomic_u8)]
 impl_atomic!(AtomicU8, u8);
-#[cfg(has_atomic_u8)]
 impl_atomic!(AtomicI8, i8);
-#[cfg(has_atomic_u16)]
 impl_atomic!(AtomicU16, u16);
-#[cfg(has_atomic_u16)]
 impl_atomic!(AtomicI16, i16);
-#[cfg(has_atomic_u32)]
 impl_atomic!(AtomicU32, u32);
-#[cfg(has_atomic_u32)]
 impl_atomic!(AtomicI32, i32);
-#[cfg(has_atomic_u64)]
+#[cfg(not(crossbeam_no_atomic_64))]
 impl_atomic!(AtomicU64, u64);
-#[cfg(has_atomic_u64)]
+#[cfg(not(crossbeam_no_atomic_64))]
 impl_atomic!(AtomicI64, i64);
 
-impl<T> AtomicConsume for ::core::sync::atomic::AtomicPtr<T> {
+#[cfg(not(crossbeam_no_atomic))]
+impl<T> AtomicConsume for core::sync::atomic::AtomicPtr<T> {
     type Val = *mut T;
     impl_consume!();
 }
 
 #[cfg(crossbeam_loom)]
-impl<T> AtomicConsume for ::loom::sync::atomic::AtomicPtr<T> {
+impl<T> AtomicConsume for loom::sync::atomic::AtomicPtr<T> {
     type Val = *mut T;
     impl_consume!();
 }
diff --git a/src/atomic/mod.rs b/src/atomic/mod.rs
index 874eaf2..fc713fc 100644
--- a/src/atomic/mod.rs
+++ b/src/atomic/mod.rs
@@ -3,11 +3,9 @@
 //! * [`AtomicCell`], a thread-safe mutable memory location.
 //! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
 
+#[cfg(not(crossbeam_no_atomic_cas))]
 #[cfg(not(crossbeam_loom))]
-use cfg_if::cfg_if;
-
-#[cfg(not(crossbeam_loom))]
-cfg_if! {
+cfg_if::cfg_if! {
     // Use "wide" sequence lock if the pointer width <= 32 for preventing its counter against wrap
     // around.
     //
@@ -25,8 +23,10 @@ cfg_if! {
     }
 }
 
+#[cfg(not(crossbeam_no_atomic_cas))]
 mod atomic_cell;
 mod consume;
 
+#[cfg(not(crossbeam_no_atomic_cas))]
 pub use self::atomic_cell::AtomicCell;
 pub use self::consume::AtomicConsume;
diff --git a/src/lib.rs b/src/lib.rs
index 880d37e..191c5a1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -38,7 +38,6 @@
     unreachable_pub
 )]
 #![cfg_attr(not(feature = "std"), no_std)]
-#![cfg_attr(feature = "nightly", feature(cfg_target_has_atomic))]
 
 #[cfg(crossbeam_loom)]
 #[allow(unused_imports)]
@@ -47,7 +46,8 @@ mod primitive {
         pub(crate) mod atomic {
             pub(crate) use loom::sync::atomic::spin_loop_hint;
             pub(crate) use loom::sync::atomic::{
-                AtomicBool, AtomicU16, AtomicU32, AtomicU64, AtomicU8, AtomicUsize,
+                AtomicBool, AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16,
+                AtomicU32, AtomicU64, AtomicU8, AtomicUsize,
             };
 
             // FIXME: loom does not support compiler_fence at the moment.
@@ -70,15 +70,13 @@ mod primitive {
             // use [`core::hint::spin_loop`] instead.
             #[allow(deprecated)]
             pub(crate) use core::sync::atomic::spin_loop_hint;
-            pub(crate) use core::sync::atomic::{AtomicBool, AtomicIsize, AtomicUsize};
-            #[cfg(has_atomic_u16)]
-            pub(crate) use core::sync::atomic::{AtomicI16, AtomicU16};
-            #[cfg(has_atomic_u32)]
-            pub(crate) use core::sync::atomic::{AtomicI32, AtomicU32};
-            #[cfg(has_atomic_u64)]
+            #[cfg(not(crossbeam_no_atomic))]
+            pub(crate) use core::sync::atomic::{
+                AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32,
+                AtomicU8, AtomicUsize,
+            };
+            #[cfg(not(crossbeam_no_atomic_64))]
             pub(crate) use core::sync::atomic::{AtomicI64, AtomicU64};
-            #[cfg(has_atomic_u8)]
-            pub(crate) use core::sync::atomic::{AtomicI8, AtomicU8};
         }
 
         #[cfg(feature = "std")]
@@ -86,15 +84,6 @@ mod primitive {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "alloc")] {
-        extern crate alloc;
-    } else if #[cfg(feature = "std")] {
-        extern crate std as alloc;
-    }
-}
-
-#[cfg_attr(feature = "nightly", cfg(target_has_atomic = "ptr"))]
 pub mod atomic;
 
 mod cache_padded;
diff --git a/tests/atomic_cell.rs b/tests/atomic_cell.rs
index 3d91d81..28208ee 100644
--- a/tests/atomic_cell.rs
+++ b/tests/atomic_cell.rs
@@ -1,3 +1,4 @@
+use std::mem;
 use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering::SeqCst;
 
@@ -8,18 +9,47 @@ fn is_lock_free() {
     struct UsizeWrap(usize);
     struct U8Wrap(bool);
     struct I16Wrap(i16);
-
-    assert_eq!(AtomicCell::<usize>::is_lock_free(), true);
-    assert_eq!(AtomicCell::<isize>::is_lock_free(), true);
-    assert_eq!(AtomicCell::<UsizeWrap>::is_lock_free(), true);
-
-    assert_eq!(AtomicCell::<u8>::is_lock_free(), cfg!(has_atomic_u8));
-    assert_eq!(AtomicCell::<bool>::is_lock_free(), cfg!(has_atomic_u8));
-    assert_eq!(AtomicCell::<U8Wrap>::is_lock_free(), cfg!(has_atomic_u8));
-
-    assert_eq!(AtomicCell::<I16Wrap>::is_lock_free(), cfg!(has_atomic_u16));
-
-    assert_eq!(AtomicCell::<u128>::is_lock_free(), cfg!(has_atomic_u128));
+    #[repr(align(8))]
+    struct U64Align8(u64);
+
+    assert!(AtomicCell::<usize>::is_lock_free());
+    assert!(AtomicCell::<isize>::is_lock_free());
+    assert!(AtomicCell::<UsizeWrap>::is_lock_free());
+
+    assert!(AtomicCell::<()>::is_lock_free());
+
+    assert!(AtomicCell::<u8>::is_lock_free());
+    assert!(AtomicCell::<i8>::is_lock_free());
+    assert!(AtomicCell::<bool>::is_lock_free());
+    assert!(AtomicCell::<U8Wrap>::is_lock_free());
+
+    assert!(AtomicCell::<u16>::is_lock_free());
+    assert!(AtomicCell::<i16>::is_lock_free());
+    assert!(AtomicCell::<I16Wrap>::is_lock_free());
+
+    assert!(AtomicCell::<u32>::is_lock_free());
+    assert!(AtomicCell::<i32>::is_lock_free());
+
+    // Sizes of both types must be equal, and the alignment of `u64` must be greater or equal than
+    // that of `AtomicU64`. In i686-unknown-linux-gnu, the alignment of `u64` is `4` and alignment
+    // of `AtomicU64` is `8`, so `AtomicCell<u64>` is not lock-free.
+    assert_eq!(
+        AtomicCell::<u64>::is_lock_free(),
+        cfg!(not(crossbeam_no_atomic_64))
+            && cfg!(any(
+                target_pointer_width = "64",
+                target_pointer_width = "128"
+            ))
+    );
+    assert_eq!(mem::size_of::<U64Align8>(), 8);
+    assert_eq!(mem::align_of::<U64Align8>(), 8);
+    assert_eq!(
+        AtomicCell::<U64Align8>::is_lock_free(),
+        cfg!(not(crossbeam_no_atomic_64))
+    );
+
+    // AtomicU128 is unstable
+    assert!(!AtomicCell::<u128>::is_lock_free());
 }
 
 #[test]
diff --git a/tests/cache_padded.rs b/tests/cache_padded.rs
index c9e7687..86e9a77 100644
--- a/tests/cache_padded.rs
+++ b/tests/cache_padded.rs
@@ -85,6 +85,7 @@ fn drops() {
     assert_eq!(count.get(), 2);
 }
 
+#[allow(clippy::clone_on_copy)] // This is intentional.
 #[test]
 fn clone() {
     let a = CachePadded::new(17);
diff --git a/tests/sharded_lock.rs b/tests/sharded_lock.rs
index b4b8565..d999008 100644
--- a/tests/sharded_lock.rs
+++ b/tests/sharded_lock.rs
@@ -148,7 +148,7 @@ fn arc() {
 fn arc_access_in_unwind() {
     let arc = Arc::new(ShardedLock::new(1));
     let arc2 = arc.clone();
-    let _ = thread::spawn(move || -> () {
+    let _ = thread::spawn(move || {
         struct Unwinder {
             i: Arc<ShardedLock<isize>>,
         }