expose is_s390x_feature_detected! from std::arch

[folkertdev]

tracking issue: #135413
implementation: rust-lang/stdarch#1699 (more features added in rust-lang/stdarch#1720)

This macro was part of the recent stdarch synchronization, but not yet exposed via std::arch.

r? libs

[Mark-Simulacrum]

@bors r+

Technically new API area, but seems basically obviously fine to add as unstable.

[bors]

📌 Commit a312635 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[uweigand]

Not sure if this is directly related, but as of a few days ago, I now see this failure in ./x.py check:

...
9   |           $(cfg!(target_feature = $target_feature_lit) ||)*
    |                  ^^^^^^^^^^^^^^
...
50  | /         macro_rules! $macro_name {
51  | |             $(
52  | |                 ($feature_lit) => {
53  | |                     $crate::detect_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?)
    | |                     -------------------------------------------------------------------------------------------------------------------------- in this macro invocation (#2)
...   |
87  | |             };
88  | |         }
    | |_________- in this expansion of `is_s390x_feature_detected!` (#1)
    |
   ::: library/std/tests/run-time-detect.rs:154:9
    |
154 |           is_s390x_feature_detected!("vector-packed-decimal-enhancement-2")
    |           ----------------------------------------------------------------- in this macro invocation (#1)
    |
    = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 266 more
    = note: using a cfg inside a macro will use the cfgs from the destination crate and not the ones from the defining crate
    = help: try referring to `$crate::detect_feature` crate for guidance on how handle this unexpected cfg
    = help: the macro `$crate::detect_feature` may come from an old version of the `std_detect` crate, try updating your dependency with `cargo update -p std_detect`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: unexpected `cfg` condition value: `vector-packed-decimal-enhancement`
   --> /home/stefansf/devel/dailyrust-workdir/rust/library/stdarch/crates/std_detect/src/detect/macros.rs:9:16
    |
4   |   macro_rules! detect_feature {
    |   ---------------------------
    |   |
    |   in this expansion of `$crate::detect_feature!` (#2)
    |   in this expansion of `$crate::detect_feature!` (#3)
5   |       ($feature:tt, $feature_lit:tt) => {
6   |           $crate::detect_feature!($feature, $feature_lit : $feature_lit)
    |           -------------------------------------------------------------- in this macro invocation (#3)
...
9   |           $(cfg!(target_feature = $target_feature_lit) ||)*
    |                  ^^^^^^^^^^^^^^
...
50  | /         macro_rules! $macro_name {
51  | |             $(
52  | |                 ($feature_lit) => {
53  | |                     $crate::detect_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?)
    | |                     -------------------------------------------------------------------------------------------------------------------------- in this macro invocation (#2)
...   |
87  | |             };
88  | |         }
    | |_________- in this expansion of `is_s390x_feature_detected!` (#1)
    |
   ::: library/std/tests/run-time-detect.rs:158:9
    |
158 |           is_s390x_feature_detected!("vector-packed-decimal-enhancement")
    |           --------------------------------------------------------------- in this macro invocation (#1)
    |
    = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 266 more
    = note: using a cfg inside a macro will use the cfgs from the destination crate and not the ones from the defining crate
    = help: try referring to `$crate::detect_feature` crate for guidance on how handle this unexpected cfg
    = help: the macro `$crate::detect_feature` may come from an old version of the `std_detect` crate, try updating your dependency with `cargo update -p std_detect`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: unexpected `cfg` condition value: `vector-packed-decimal`
   --> /home/stefansf/devel/dailyrust-workdir/rust/library/stdarch/crates/std_detect/src/detect/macros.rs:9:16
    |
4   |   macro_rules! detect_feature {
    |   ---------------------------
    |   |
    |   in this expansion of `$crate::detect_feature!` (#2)
    |   in this expansion of `$crate::detect_feature!` (#3)
5   |       ($feature:tt, $feature_lit:tt) => {
6   |           $crate::detect_feature!($feature, $feature_lit : $feature_lit)
    |           -------------------------------------------------------------- in this macro invocation (#3)
...
9   |           $(cfg!(target_feature = $target_feature_lit) ||)*
    |                  ^^^^^^^^^^^^^^
...
50  | /         macro_rules! $macro_name {
51  | |             $(
52  | |                 ($feature_lit) => {
53  | |                     $crate::detect_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?)
    | |                     -------------------------------------------------------------------------------------------------------------------------- in this macro invocation (#2)
...   |
87  | |             };
88  | |         }
    | |_________- in this expansion of `is_s390x_feature_detected!` (#1)
    |
   ::: library/std/tests/run-time-detect.rs:160:43
    |
160 |       println!("vector-packed-decimal: {}", is_s390x_feature_detected!("vector-packed-decimal"));
    |                                             --------------------------------------------------- in this macro invocation (#1)
    |
    = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 266 more
    = note: using a cfg inside a macro will use the cfgs from the destination crate and not the ones from the defining crate
    = help: try referring to `$crate::detect_feature` crate for guidance on how handle this unexpected cfg
    = help: the macro `$crate::detect_feature` may come from an old version of the `std_detect` crate, try updating your dependency with `cargo update -p std_detect`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: could not compile `std` (test "run-time-detect") due to 11 previous errors
warning: build failed, waiting for other jobs to finish...
Build completed unsuccessfully in 0:00:30

[folkertdev]

I suspect this is a caching issue of some kind? I ran run the following just fine (with qemu)

#![cfg_attr(
    all(target_arch = "s390x", target_os = "linux"),
    feature(stdarch_s390x_feature_detection)
)]

use std::arch::is_s390x_feature_detected;
fn main() {
    println!(
        "vector-packed-decimal-enhancement-2: {}",
        is_s390x_feature_detected!("vector-packed-decimal-enhancement-2")
    );
}

on current nightly. You could try a ./x clean maybe? (I'm assuming you are on a commit that should have this macro exposed?)

[uweigand]

I still see the failure today after cleaning everything. The failure occurs during stage0 library build, where the std library sources included in the Rust repo (rust/library/std) are being built with the bootstrap compiler (https://static.rust-lang.org/dist/2025-02-18/rustc-beta-s390x-unknown-linux-gnu.tar.xz). Is this supposed to work now?

[folkertdev]

I believe bootstrap updates in tandem with the standard releases, so maybe wait for that?