rust/library/compiler-builtins/libm/build.rs

use std::env;

mod configure;

fn main() {
    let cfg = configure::Config::from_env();

    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rustc-check-cfg=cfg(assert_no_panic)");

    println!("cargo:rustc-check-cfg=cfg(feature, values(\"checked\"))");

    #[allow(unexpected_cfgs)]
    if !cfg!(feature = "checked") {
        let lvl = env::var("OPT_LEVEL").unwrap();
        if lvl != "0" {
            println!("cargo:rustc-cfg=assert_no_panic");
        }
    }

    configure::emit_libm_config(&cfg);
}