1 // The rustc-cfg listed below are considered public API, but it is *unstable*
2 // and outside of the normal semver guarantees:
3 //
4 // - `crossbeam_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 // - `crossbeam_no_atomic`
11 // Assume the target does *not* support any atomic operations.
12 // This is usually detected automatically by the build script, but you may
13 // need to enable it manually when building for custom targets or using
14 // non-cargo build systems that don't run the build script.
15 //
16 // - `crossbeam_no_atomic_64`
17 // Assume the target does *not* support AtomicU64/AtomicI64.
18 // This is usually detected automatically by the build script, but you may
19 // need to enable it manually when building for custom targets or using
20 // non-cargo build systems that don't run the build script.
21 //
22 // With the exceptions mentioned above, the rustc-cfg emitted by the build
23 // script are *not* public API.
24
25 #![warn(rust_2018_idioms)]
26
27 use std::env;
28
29 include!("no_atomic.rs");
30
main()31 fn main() {
32 let target = match env::var("TARGET") {
33 Ok(target) => target,
34 Err(e) => {
35 println!(
36 "cargo:warning={}: unable to get TARGET environment variable: {}",
37 env!("CARGO_PKG_NAME"),
38 e
39 );
40 return;
41 }
42 };
43
44 // Note that this is `no_*`, not `has_*`. This allows treating
45 // `cfg(target_has_atomic = "ptr")` as true when the build script doesn't
46 // run. This is needed for compatibility with non-cargo build systems that
47 // don't run the build script.
48 if NO_ATOMIC_CAS.contains(&&*target) {
49 println!("cargo:rustc-cfg=crossbeam_no_atomic_cas");
50 }
51 if NO_ATOMIC.contains(&&*target) {
52 println!("cargo:rustc-cfg=crossbeam_no_atomic");
53 println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
54 } else if NO_ATOMIC_64.contains(&&*target) {
55 println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
56 } else {
57 // Otherwise, assuming `"max-atomic-width" == 64` or `"max-atomic-width" == 128`.
58 }
59
60 println!("cargo:rerun-if-changed=no_atomic.rs");
61 }
62