// SPDX-License-Identifier: Apache-2.0 OR MIT
// The rustc-cfg emitted by the build script are *not* public API.
#![allow(clippy::match_same_arms)] // https://github.com/rust-lang/rust-clippy/issues/12044
#[path = "version.rs"]
mod version;
use version::{rustc_version, Version};
use std::{env, str};
include!("no_atomic.rs");
fn main() {
println!("cargo:rerun-if-changed=build.rs");
println!("cargo:rerun-if-changed=no_atomic.rs");
println!("cargo:rerun-if-changed=version.rs");
#[cfg(feature = "unsafe-assume-single-core")]
println!("cargo:rustc-cfg=portable_atomic_unsafe_assume_single_core");
#[cfg(feature = "s-mode")]
println!("cargo:rustc-cfg=portable_atomic_s_mode");
#[cfg(feature = "force-amo")]
println!("cargo:rustc-cfg=portable_atomic_force_amo");
#[cfg(feature = "disable-fiq")]
println!("cargo:rustc-cfg=portable_atomic_disable_fiq");
let target = &*env::var("TARGET").expect("TARGET not set");
let target_arch = &*env::var("CARGO_CFG_TARGET_ARCH").expect("CARGO_CFG_TARGET_ARCH not set");
let target_os = &*env::var("CARGO_CFG_TARGET_OS").expect("CARGO_CFG_TARGET_OS not set");
let version = match rustc_version() {
Some(version) => version,
None => {
if env::var_os("PORTABLE_ATOMIC_DENY_WARNINGS").is_some() {
panic!("unable to determine rustc version")
}
println!(
"cargo:warning={}: unable to determine rustc version; assuming latest stable rustc (1.{})",
env!("CARGO_PKG_NAME"),
Version::LATEST.minor
);
Version::LATEST
}
};
if version.minor >= 80 {
println!(
r#"cargo:rustc-check-cfg=cfg(target_feature,values("zaamo","zabha","experimental-zacas","fast-serialization","load-store-on-cond","distinct-ops","miscellaneous-extensions-3"))"#
);
// Custom cfgs set by build script. Not public API.
// grep -F 'cargo:rustc-cfg=' build.rs | grep -Ev '^ *//' | sed -E 's/^.*cargo:rustc-cfg=//; s/(=\\)?".*$//' | LC_ALL=C sort -u | tr '\n' ',' | sed -E 's/,$/\n/'
println!(
"cargo:rustc-check-cfg=cfg(portable_atomic_disable_fiq,portable_atomic_force_amo,portable_atomic_ll_sc_rmw,portable_atomic_pre_llvm_15,portable_atomic_pre_llvm_16,portable_atomic_pre_llvm_18,portable_atomic_pre_llvm_19,portable_atomic_new_atomic_intrinsics,portable_atomic_no_asm,portable_atomic_no_asm_maybe_uninit,portable_atomic_no_atomic_64,portable_atomic_no_atomic_cas,portable_atomic_no_atomic_load_store,portable_atomic_no_atomic_min_max,portable_atomic_no_cfg_target_has_atomic,portable_atomic_no_cmpxchg16b_intrinsic,portable_atomic_no_cmpxchg16b_target_feature,portable_atomic_no_const_raw_ptr_deref,portable_atomic_no_const_transmute,portable_atomic_no_core_unwind_safe,portable_atomic_no_diagnostic_namespace,portable_atomic_no_stronger_failure_ordering,portable_atomic_no_track_caller,portable_atomic_no_unsafe_op_in_unsafe_fn,portable_atomic_s_mode,portable_atomic_sanitize_thread,portable_atomic_target_feature,portable_atomic_unsafe_assume_single_core,portable_atomic_unstable_asm,portable_atomic_unstable_asm_experimental_arch,portable_atomic_unstable_cfg_target_has_atomic,portable_atomic_unstable_isa_attribute)"
);
// TODO: handle multi-line target_feature_fallback
// grep -F 'target_feature_fallback("' build.rs | grep -Ev '^ *//' | sed -E 's/^.*target_feature_fallback\(//; s/",.*$/"/' | LC_ALL=C sort -u | tr '\n' ',' | sed -E 's/,$/\n/'
println!(
r#"cargo:rustc-check-cfg=cfg(portable_atomic_target_feature,values("cmpxchg16b","distinct-ops","experimental-zacas","fast-serialization","load-store-on-cond","lse","lse128","lse2","mclass","miscellaneous-extensions-3","quadword-atomics","rcpc3","v6","zaamo","zabha"))"#
);
}
// https://github.com/rust-lang/rust/pull/123745 (includes https://github.com/rust-lang/cargo/pull/13560) merged in Rust 1.79 (nightly-2024-04-11).
if !version.probe(79, 2024, 4, 10) {
// HACK: If --target is specified, rustflags is not applied to the build
// script itself, so the build script will not be recompiled when rustflags
// is changed. That in itself is not a problem, but the old Cargo does
// not rerun the build script as well, which can be problematic.
// https://github.com/rust-lang/cargo/issues/13003
// This problem has been fixed in 1.79 so only older versions need a workaround.
println!("cargo:rerun-if-env-changed=CARGO_ENCODED_RUSTFLAGS");
println!("cargo:rerun-if-env-changed=RUSTFLAGS");
println!("cargo:rerun-if-env-changed=CARGO_BUILD_RUSTFLAGS");
let mut target_upper = target.replace(|c: char| c == '-' || c == '.', "_");
target_upper.make_ascii_uppercase();
println!("cargo:rerun-if-env-changed=CARGO_TARGET_{}_RUSTFLAGS", target_upper);
}
// Note that cfgs are `no_`*, not `has_*`. This allows treating as the latest
// stable rustc is used when the build script doesn't run. This is useful
// for non-cargo build systems that don't run the build script.
// atomic_min_max stabilized in Rust 1.45 (nightly-2020-05-30): https://github.com/rust-lang/rust/pull/72324
if !version.probe(45, 2020, 5, 29) {
println!("cargo:rustc-cfg=portable_atomic_no_atomic_min_max");
}
// track_caller stabilized in Rust 1.46 (nightly-2020-07-02): https://github.com/rust-lang/rust/pull/72445
if !version.probe(46, 2020, 7, 1) {
println!("cargo:rustc-cfg=portable_atomic_no_track_caller");
}
// unsafe_op_in_unsafe_fn stabilized in Rust 1.52 (nightly-2021-03-11): https://github.com/rust-lang/rust/pull/79208
if !version.probe(52, 2021, 3, 10) {
println!("cargo:rustc-cfg=portable_atomic_no_unsafe_op_in_unsafe_fn");
}
// const_transmute stabilized in Rust 1.56 (nightly-2021-07-29): https://github.com/rust-lang/rust/pull/85769
if !version.probe(56, 2021, 7, 28) {
println!("cargo:rustc-cfg=portable_atomic_no_const_transmute");
}
// https://github.com/rust-lang/rust/pull/84662 merged in Rust 1.56 (nightly-2021-08-02).
if !version.probe(56, 2021, 8, 1) {
println!("cargo:rustc-cfg=portable_atomic_no_core_unwind_safe");
}
// const_raw_ptr_deref stabilized in Rust 1.58 (nightly-2021-11-15): https://github.com/rust-lang/rust/pull/89551
if !version.probe(58, 2021, 11, 14) {
println!("cargo:rustc-cfg=portable_atomic_no_const_raw_ptr_deref");
}
// https://github.com/rust-lang/rust/pull/98383 merged in Rust 1.64 (nightly-2022-07-19).
if !version.probe(64, 2022, 7, 18) {
println!("cargo:rustc-cfg=portable_atomic_no_stronger_failure_ordering");
}
// https://github.com/rust-lang/rust/pull/114790 merged in nightly-2023-08-24
if !version.probe(74, 2023, 8, 23) {
println!("cargo:rustc-cfg=portable_atomic_no_asm_maybe_uninit");
}
// #[diagnostic] stabilized in Rust 1.78 (nightly-2024-03-09): https://github.com/rust-lang/rust/pull/119888
if !version.probe(78, 2024, 3, 8) {
println!("cargo:rustc-cfg=portable_atomic_no_diagnostic_namespace");
}
// asm stabilized in Rust 1.59 (nightly-2021-12-16): https://github.com/rust-lang/rust/pull/91728
let no_asm = !version.probe(59, 2021, 12, 15);
if no_asm {
if version.nightly
&& version.probe(46, 2020, 6, 20)
&& ((target_arch != "x86" && target_arch != "x86_64") || version.llvm >= 10)
&& is_allowed_feature("asm")
{
// This feature was added in Rust 1.45 (nightly-2020-05-20), but
// concat! in asm! requires Rust 1.46 (nightly-2020-06-21).
// x86 intel syntax requires LLVM 10 (since Rust 1.53, the minimum
// external LLVM version is 10+: https://github.com/rust-lang/rust/pull/83387).
// The part of this feature we use has not been changed since nightly-2020-06-21
// until it was stabilized in nightly-2021-12-16, so it can be safely enabled in
// nightly, which is older than nightly-2021-12-16.
println!("cargo:rustc-cfg=portable_atomic_unstable_asm");
}
println!("cargo:rustc-cfg=portable_atomic_no_asm");
}
// feature(cfg_target_has_atomic) stabilized in Rust 1.60 (nightly-2022-02-11): https://github.com/rust-lang/rust/pull/93824
if !version.probe(60, 2022, 2, 10) {
if version.nightly
&& version.probe(40, 2019, 10, 13)
&& is_allowed_feature("cfg_target_has_atomic")
{
// This feature has not been changed since the change in Rust 1.40 (nightly-2019-10-14)
// until it was stabilized in nightly-2022-02-11, so it can be safely enabled in
// nightly, which is older than nightly-2022-02-11.
println!("cargo:rustc-cfg=portable_atomic_unstable_cfg_target_has_atomic");
} else {
println!("cargo:rustc-cfg=portable_atomic_no_cfg_target_has_atomic");
let target = &*convert_custom_linux_target(target);
if NO_ATOMIC_CAS.contains(&target) {
println!("cargo:rustc-cfg=portable_atomic_no_atomic_cas");
}
if NO_ATOMIC_64.contains(&target) {
println!("cargo:rustc-cfg=portable_atomic_no_atomic_64");
} else {
// Otherwise, assuming `"max-atomic-width" == 64` or `"max-atomic-width" == 128`.
}
}
}
// We don't need to use convert_custom_linux_target here because all linux targets have atomics.
if NO_ATOMIC.contains(&target) {
println!("cargo:rustc-cfg=portable_atomic_no_atomic_load_store");
}
if version.llvm < 19 {
println!("cargo:rustc-cfg=portable_atomic_pre_llvm_19");
if version.llvm < 18 {
println!("cargo:rustc-cfg=portable_atomic_pre_llvm_18");
if version.llvm < 16 {
println!("cargo:rustc-cfg=portable_atomic_pre_llvm_16");
if version.llvm < 15 {
println!("cargo:rustc-cfg=portable_atomic_pre_llvm_15");
}
}
}
}
if version.nightly {
// `cfg(sanitize = "..")` is not stabilized.
let sanitize = env::var("CARGO_CFG_SANITIZE").unwrap_or_default();
if sanitize.contains("thread") {
// Most kinds of sanitizers are not compatible with asm
// (https://github.com/google/sanitizers/issues/192),
// but it seems that ThreadSanitizer is the only one that can cause
// false positives in our code.
println!("cargo:rustc-cfg=portable_atomic_sanitize_thread");
}
// https://github.com/rust-lang/rust/pull/93868 merged in Rust 1.60 (nightly-2022-02-13).
// https://github.com/rust-lang/rust/pull/111331 merged in Rust 1.71 (nightly-2023-05-09).
if !no_asm
&& (target_arch == "powerpc64" && version.probe(60, 2022, 2, 12)
|| target_arch == "s390x" && version.probe(71, 2023, 5, 8)
|| target_arch == "arm64ec")
&& is_allowed_feature("asm_experimental_arch")
{
println!("cargo:rustc-cfg=portable_atomic_unstable_asm_experimental_arch");
}
}
match target_arch {
"x86_64" => {
// cmpxchg16b_target_feature stabilized in Rust 1.69 (nightly-2023-03-01): https://github.com/rust-lang/rust/pull/106774
if !version.probe(69, 2023, 2, 28) {
println!("cargo:rustc-cfg=portable_atomic_no_cmpxchg16b_target_feature");
}
// For Miri and ThreadSanitizer.
// https://github.com/rust-lang/rust/pull/109359 (includes https://github.com/rust-lang/stdarch/pull/1358) merged in Rust 1.70 (nightly-2023-03-24).
if version.nightly && !version.probe(70, 2023, 3, 23) {
println!("cargo:rustc-cfg=portable_atomic_no_cmpxchg16b_intrinsic");
}
// cmpxchg16b_target_feature stabilized in Rust 1.69.
if needs_target_feature_fallback(&version, Some(69)) {
// x86_64 Apple targets always support CMPXCHG16B:
// https://github.com/rust-lang/rust/blob/1.68.0/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs#L8
// https://github.com/rust-lang/rust/blob/1.68.0/compiler/rustc_target/src/spec/apple_base.rs#L69-L70
// (Since Rust 1.78, Windows (except Windows 7) targets also enable CMPXCHG16B, but
// this branch is only used on pre-1.69 that cmpxchg16b_target_feature is unstable.)
// Script to get builtin targets that support CMPXCHG16B by default:
// $ (for target in $(rustc --print target-list | grep -E '^x86_64'); do rustc --print cfg --target "${target}" | grep -Fq '"cmpxchg16b"' && printf '%s\n' "${target}"; done)
let is_apple = env::var("CARGO_CFG_TARGET_VENDOR").unwrap_or_default() == "apple";
let has_cmpxchg16b = is_apple;
// LLVM recognizes this also as cx16 target feature: https://godbolt.org/z/KM3jz616j
// However, it is unlikely that rustc will support that name, so we ignore it.
target_feature_fallback("cmpxchg16b", has_cmpxchg16b);
}
}
"aarch64" | "arm64ec" => {
// For Miri and ThreadSanitizer.
// https://github.com/rust-lang/rust/pull/97423 merged in Rust 1.64 (nightly-2022-06-30).
if version.nightly && version.probe(64, 2022, 6, 29) {
println!("cargo:rustc-cfg=portable_atomic_new_atomic_intrinsics");
}
// target_feature "lse2"/"lse128"/"rcpc3" is unstable and available on rustc side since nightly-2024-08-30: https://github.com/rust-lang/rust/pull/128192
if !version.probe(82, 2024, 8, 29) || needs_target_feature_fallback(&version, None) {
// FEAT_LSE2 doesn't imply FEAT_LSE. FEAT_LSE128 implies FEAT_LSE but not FEAT_LSE2.
// AArch64 macOS always supports FEAT_LSE and FEAT_LSE2 because M1 is Armv8.4 with all features of Armv8.5 except FEAT_BTI:
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/AArch64/AArch64Processors.td#L1203
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/AArch64/AArch64Processors.td#L865
// Script to get builtin targets that support FEAT_LSE/FEAT_LSE2 by default:
// $ (for target in $(rustc --print target-list | grep -E '^aarch64|^arm64'); do rustc --print cfg --target "${target}" | grep -Fq '"lse"' && printf '%s\n' "${target}"; done)
// $ (for target in $(rustc --print target-list | grep -E '^aarch64|^arm64'); do rustc --print cfg --target "${target}" | grep -Fq '"lse2"' && printf '%s\n' "${target}"; done)
let is_macos = target_os == "macos";
let mut has_lse = is_macos;
target_feature_fallback("lse2", is_macos);
has_lse |= target_feature_fallback("lse128", false);
target_feature_fallback("rcpc3", false);
// aarch64_target_feature stabilized in Rust 1.61.
if needs_target_feature_fallback(&version, Some(61)) {
target_feature_fallback("lse", has_lse);
}
}
// As of Apple M1/M1 Pro, on Apple hardware, CAS-loop-based RMW is much slower than
// LL/SC-loop-based RMW: https://github.com/taiki-e/portable-atomic/pull/89
let is_apple = env::var("CARGO_CFG_TARGET_VENDOR").unwrap_or_default() == "apple";
if is_apple || target_cpu().map_or(false, |cpu| cpu.starts_with("apple-")) {
println!("cargo:rustc-cfg=portable_atomic_ll_sc_rmw");
}
}
"arm" => {
// For non-Linux/Android pre-v6 Arm (tier 3) with unsafe_assume_single_core enabled.
// feature(isa_attribute) stabilized in Rust 1.67 (nightly-2022-11-06): https://github.com/rust-lang/rust/pull/102458
if version.nightly && !version.probe(67, 2022, 11, 5) {
println!("cargo:rustc-cfg=portable_atomic_unstable_isa_attribute");
}
if needs_target_feature_fallback(&version, None) {
// #[cfg(target_feature = "v7")] and others don't work on stable.
// armv7-unknown-linux-gnueabihf
// ^^
let mut subarch =
strip_prefix(target, "arm").or_else(|| strip_prefix(target, "thumb")).unwrap();
subarch = strip_prefix(subarch, "eb").unwrap_or(subarch); // ignore endianness
subarch = subarch.split('-').next().unwrap(); // ignore vender/os/env
subarch = subarch.split('.').next().unwrap(); // ignore .base/.main suffix
let mut known = true;
// See https://github.com/taiki-e/atomic-maybe-uninit/blob/HEAD/build.rs for details
let mut mclass = false;
match subarch {
"v7" | "v7a" | "v7neon" | "v7s" | "v7k" | "v8" | "v8a" | "v9" | "v9a" => {} // aclass
"v7r" | "v8r" | "v9r" => {} // rclass
"v6m" | "v7em" | "v7m" | "v8m" => mclass = true,
// arm-linux-androideabi is v5te
// https://github.com/rust-lang/rust/blob/1.80.0/compiler/rustc_target/src/spec/targets/arm_linux_androideabi.rs#L18
_ if target == "arm-linux-androideabi" => subarch = "v5te",
// armeb-unknown-linux-gnueabi is v8 & aclass
// https://github.com/rust-lang/rust/blob/1.80.0/compiler/rustc_target/src/spec/targets/armeb_unknown_linux_gnueabi.rs#L18
_ if target == "armeb-unknown-linux-gnueabi" => subarch = "v8",
// Legacy Arm architectures (pre-v7 except v6m) don't have *class target feature.
"" => subarch = "v6",
"v4t" | "v5te" | "v6" | "v6k" => {}
_ => {
known = false;
if env::var_os("PORTABLE_ATOMIC_DENY_WARNINGS").is_some() {
panic!("unrecognized Arm subarch: {}", target)
}
println!(
"cargo:warning={}: unrecognized Arm subarch: {}",
env!("CARGO_PKG_NAME"),
target
);
}
}
let v6 = known
&& (subarch.starts_with("v6")
|| subarch.starts_with("v7")
|| subarch.starts_with("v8")
|| subarch.starts_with("v9"));
target_feature_fallback("v6", v6);
target_feature_fallback("mclass", mclass);
}
}
"riscv32" | "riscv64" => {
// As of rustc 1.80, target_feature "zaamo"/"zabha"/"zacas" is not available on rustc side:
// https://github.com/rust-lang/rust/blob/1.80.0/compiler/rustc_target/src/target_features.rs#L273
// zabha and zacas imply zaamo in GCC, but do not in LLVM (but enabling them without zaamo is not allowed).
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/TargetParser/RISCVISAInfo.cpp#L772-L778
// https://github.com/gcc-mirror/gcc/blob/08693e29ec186fd7941d0b73d4d466388971fe2f/gcc/config/riscv/arch-canonicalize#L45-L46
if version.llvm >= 19 {
// amo*.{b,h}
// available since LLVM 19 https://github.com/llvm/llvm-project/commit/89f87c387627150d342722b79c78cea2311cddf7 / https://github.com/llvm/llvm-project/commit/6b7444964a8d028989beee554a1f5c61d16a1cac
target_feature_fallback("zabha", false);
}
if version.llvm == 19 {
// amocas.{w,d,q} (and amocas.{b,h} if zabha is also available)
// available as experimental since LLVM 17 https://github.com/llvm/llvm-project/commit/29f630a1ddcbb03caa31b5002f0cbc105ff3a869
// attempted to make non-experimental in LLVM 19 https://github.com/llvm/llvm-project/commit/95aab69c109adf29e183090c25dc95c773215746
// but reverted in https://github.com/llvm/llvm-project/commit/70e7d26e560173c8b9db4c75ab4a3004cd5f021a
// check == 19 instead of range 17..=19 because it is more experimental in LLVM 17/18.
// check == 19 instead of >= 19 because "experimental-zacas" feature
// may no longer exist when it is marked as non-experimental in LLVM 20.
target_feature_fallback("experimental-zacas", false);
}
// amo*.{w,d}
target_feature_fallback("zaamo", false);
}
"powerpc64" => {
// target_feature "quadword-atomics" is unstable and available on rustc side since nightly-2024-09-28: https://github.com/rust-lang/rust/pull/130873
if !version.probe(83, 2024, 9, 27) || needs_target_feature_fallback(&version, None) {
let target_endian =
env::var("CARGO_CFG_TARGET_ENDIAN").expect("CARGO_CFG_TARGET_ENDIAN not set");
// powerpc64le is pwr8+ by default https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/PowerPC/PPC.td#L702
// See also https://github.com/rust-lang/rust/issues/59932
let mut has_pwr8_features = target_endian == "little";
// https://github.com/llvm/llvm-project/commit/549e118e93c666914a1045fde38a2cac33e1e445
if let Some(cpu) = &target_cpu() {
if let Some(mut cpu_version) = strip_prefix(cpu, "pwr") {
cpu_version = strip_suffix(cpu_version, "x").unwrap_or(cpu_version); // for pwr5x and pwr6x
if let Ok(cpu_version) = cpu_version.parse::<u32>() {
has_pwr8_features = cpu_version >= 8;
}
} else {
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/PowerPC/PPC.td#L702
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/PowerPC/PPC.td#L483
// On the minimum external LLVM version of the oldest rustc version which we can use asm_experimental_arch
// on this target (see CI config for more), "future" is based on pwr10 features.
// https://github.com/llvm/llvm-project/blob/llvmorg-12.0.0/llvm/lib/Target/PowerPC/PPC.td#L370
has_pwr8_features = cpu == "ppc64le" || cpu == "future";
}
}
// lqarx and stqcx.
target_feature_fallback("quadword-atomics", has_pwr8_features);
}
}
"s390x" => {
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/SystemZ/SystemZFeatures.td
let mut arch9_features = false; // z196+
let mut arch13_features = false; // z15+
if let Some(cpu) = target_cpu() {
// LLVM and GCC recognize the same names:
// https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/SystemZ/SystemZProcessors.td
// https://github.com/gcc-mirror/gcc/blob/releases/gcc-14.2.0/gcc/config/s390/s390.opt#L58-L125
match &*cpu {
"arch9" | "z196" | "arch10" | "zEC12" | "arch11" | "z13" | "arch12" | "z14" => {
arch9_features = true;
}
"arch13" | "z15" | "arch14" | "z16" => {
arch9_features = true;
arch13_features = true;
}
_ => {}
}
}
// As of rustc 1.80, target_feature "fast-serialization"/"load-store-on-cond"/"distinct-ops"/"miscellaneous-extensions-3" is not available on rustc side:
// https://github.com/rust-lang/rust/blob/1.80.0/compiler/rustc_target/src/target_features.rs
// bcr 14,0
target_feature_fallback("fast-serialization", arch9_features);
// {l,st}oc{,g}{,r}
target_feature_fallback("load-store-on-cond", arch9_features);
// {al,sl,n,o,x}{,g}rk
target_feature_fallback("distinct-ops", arch9_features);
// nand (nnr{,g}k), select (sel{,g}r), etc.
target_feature_fallback("miscellaneous-extensions-3", arch13_features);
}
_ => {}
}
}
// HACK: Currently, it seems that the only way to handle unstable target
// features on the stable is to parse the `-C target-feature` in RUSTFLAGS.
//
// - #[cfg(target_feature = "unstable_target_feature")] doesn't work on stable.
// - CARGO_CFG_TARGET_FEATURE excludes unstable target features on stable.
//
// As mentioned in the [RFC2045], unstable target features are also passed to LLVM
// (e.g., https://godbolt.org/z/4rr7rMcfG), so this hack works properly on stable.
//
// [RFC2045]: https://rust-lang.github.io/rfcs/2045-target-feature.html#backend-compilation-options
fn needs_target_feature_fallback(version: &Version, stable: Option<u32>) -> bool {
match stable {
// In these cases, cfg(target_feature = "...") would work, so skip emitting our own fallback target_feature cfg.
_ if version.nightly => false,
Some(stabilized) if version.minor >= stabilized => false,
_ => true,
}
}
fn target_feature_fallback(name: &str, mut has_target_feature: bool) -> bool {
if let Some(rustflags) = env::var_os("CARGO_ENCODED_RUSTFLAGS") {
for mut flag in rustflags.to_string_lossy().split('\x1f') {
flag = strip_prefix(flag, "-C").unwrap_or(flag);
if let Some(flag) = strip_prefix(flag, "target-feature=") {
for s in flag.split(',') {
// TODO: Handles cases where a specific target feature
// implicitly enables another target feature.
match (s.as_bytes().first(), s.as_bytes().get(1..)) {
(Some(b'+'), Some(f)) if f == name.as_bytes() => has_target_feature = true,
(Some(b'-'), Some(f)) if f == name.as_bytes() => has_target_feature = false,
_ => {}
}
}
}
}
}
if has_target_feature {
println!("cargo:rustc-cfg=portable_atomic_target_feature=\"{}\"", name);
}
has_target_feature
}
fn target_cpu() -> Option<String> {
let rustflags = env::var_os("CARGO_ENCODED_RUSTFLAGS")?;
let rustflags = rustflags.to_string_lossy();
let mut cpu = None;
for mut flag in rustflags.split('\x1f') {
flag = strip_prefix(flag, "-C").unwrap_or(flag);
if let Some(flag) = strip_prefix(flag, "target-cpu=") {
cpu = Some(flag);
}
}
cpu.map(str::to_owned)
}
fn is_allowed_feature(name: &str) -> bool {
// https://github.com/dtolnay/thiserror/pull/248
if env::var_os("RUSTC_STAGE").is_some() {
return false;
}
// allowed by default
let mut allowed = true;
if let Some(rustflags) = env::var_os("CARGO_ENCODED_RUSTFLAGS") {
for mut flag in rustflags.to_string_lossy().split('\x1f') {
flag = strip_prefix(flag, "-Z").unwrap_or(flag);
if let Some(flag) = strip_prefix(flag, "allow-features=") {
// If it is specified multiple times, the last value will be preferred.
allowed = flag.split(',').any(|allowed| allowed == name);
}
}
}
allowed
}
// Adapted from https://github.com/crossbeam-rs/crossbeam/blob/crossbeam-utils-0.8.14/build-common.rs.
//
// The target triplets have the form of 'arch-vendor-system'.
//
// When building for Linux (e.g. the 'system' part is
// 'linux-something'), replace the vendor with 'unknown'
// so that mapping to rust standard targets happens correctly.
fn convert_custom_linux_target(target: &str) -> String {
let mut parts: Vec<&str> = target.split('-').collect();
let system = parts.get(2);
if system == Some(&"linux") {
parts[1] = "unknown";
}
parts.join("-")
}
// str::strip_prefix requires Rust 1.45
#[must_use]
fn strip_prefix<'a>(s: &'a str, pat: &str) -> Option<&'a str> {
if s.starts_with(pat) {
Some(&s[pat.len()..])
} else {
None
}
}
// str::strip_suffix requires Rust 1.45
#[must_use]
fn strip_suffix<'a>(s: &'a str, pat: &str) -> Option<&'a str> {
if s.ends_with(pat) {
Some(&s[..s.len() - pat.len()])
} else {
None
}
}