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Change flags for having an atomic u64 #5284

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Dec 16, 2022
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31 changes: 31 additions & 0 deletions tokio/build.rs
Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,17 @@ const CONST_MUTEX_NEW_PROBE: &str = r#"
}
"#;

const TARGET_HAS_ATOMIC_PROBE: &str = r#"
{
#[cfg(target_has_atomic = "ptr")]
let _ = ();
}
"#;

fn main() {
let mut enable_const_thread_local = false;
let mut enable_addr_of = false;
let mut enable_target_has_atomic = false;
let mut enable_const_mutex_new = false;

match AutoCfg::new() {
Expand Down Expand Up @@ -66,6 +74,21 @@ fn main() {
}
}

// The `target_has_atomic` cfg was stabilized in 1.60.
if ac.probe_rustc_version(1, 61) {
enable_target_has_atomic = true;
} else if ac.probe_rustc_version(1, 60) {
// This compiler claims to be 1.60, but there are some nightly
// compilers that claim to be 1.60 without supporting the
// feature. Explicitly probe to check if code using them
// compiles.
//
// The oldest nightly that supports the feature is 2022-02-11.
if ac.probe_expression(TARGET_HAS_ATOMIC_PROBE) {
enable_target_has_atomic = true;
}
}

// The `Mutex::new` method was made const in 1.63.
if ac.probe_rustc_version(1, 64) {
enable_const_mutex_new = true;
Expand Down Expand Up @@ -109,6 +132,14 @@ fn main() {
autocfg::emit("tokio_no_addr_of")
}

if !enable_target_has_atomic {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
//
// RUSTFLAGS="--cfg tokio_no_target_has_atomic"
autocfg::emit("tokio_no_target_has_atomic")
}

if !enable_const_mutex_new {
// To disable this feature on compilers that support it, you can
// explicitly pass this flag with the following environment variable:
Expand Down
44 changes: 29 additions & 15 deletions tokio/src/macros/cfg.rs
Original file line number Diff line number Diff line change
Expand Up @@ -461,14 +461,21 @@ macro_rules! cfg_not_coop {
macro_rules! cfg_has_atomic_u64 {
($($item:item)*) => {
$(
#[cfg(not(any(
target_arch = "arm",
target_arch = "mips",
target_arch = "powerpc",
target_arch = "riscv32",
tokio_wasm,
tokio_no_atomic_u64,
)))]
#[cfg_attr(
not(tokio_no_target_has_atomic),
cfg(all(target_has_atomic = "64", not(tokio_no_atomic_u64))
))]
#[cfg_attr(
tokio_no_target_has_atomic,
cfg(not(any(
target_arch = "arm",
target_arch = "mips",
target_arch = "powerpc",
target_arch = "riscv32",
tokio_wasm,
tokio_no_atomic_u64,
)))
)]
$item
)*
}
Expand All @@ -477,14 +484,21 @@ macro_rules! cfg_has_atomic_u64 {
macro_rules! cfg_not_has_atomic_u64 {
($($item:item)*) => {
$(
#[cfg(any(
target_arch = "arm",
target_arch = "mips",
target_arch = "powerpc",
target_arch = "riscv32",
tokio_wasm,
tokio_no_atomic_u64,
#[cfg_attr(
not(tokio_no_target_has_atomic),
cfg(any(not(target_has_atomic = "64"), tokio_no_atomic_u64)
))]
#[cfg_attr(
tokio_no_target_has_atomic,
cfg(any(
target_arch = "arm",
target_arch = "mips",
target_arch = "powerpc",
target_arch = "riscv32",
tokio_wasm,
tokio_no_atomic_u64,
))
)]
$item
)*
}
Expand Down