1// The rustc-cfg listed below are considered public API, but it is *unstable*
2// and outside of the normal semver guarantees:
3//
4// - `futures_no_atomic_cas`
5// Assume the target does *not* support atomic CAS operations.
6// This is usually detected automatically by the build script, but you may
7// need to enable it manually when building for custom targets or using
8// non-cargo build systems that don't run the build script.
9//
10// With the exceptions mentioned above, the rustc-cfg emitted by the build
11// script are *not* public API.
12
13#![warn(rust_2018_idioms, single_use_lifetimes)]
14
15use std::env;
16
17include!("no_atomic_cas.rs");
18
19fn main() {
20 let target = match env::var("TARGET") {
21 Ok(target) => target,
22 Err(e) => {
23 println!(
24 "cargo:warning={}: unable to get TARGET environment variable: {}",
25 env!("CARGO_PKG_NAME"),
26 e
27 );
28 return;
29 }
30 };
31
32 // Note that this is `no_*`, not `has_*`. This allows treating
33 // `cfg(target_has_atomic = "ptr")` as true when the build script doesn't
34 // run. This is needed for compatibility with non-cargo build systems that
35 // don't run the build script.
36 if NO_ATOMIC_CAS.contains(&&*target) {
37 println!("cargo:rustc-cfg=futures_no_atomic_cas");
38 }
39
40 println!("cargo:rerun-if-changed=no_atomic_cas.rs");
41}
42