1 use std::env; 2 main()3fn main() { 4 println!("cargo:rerun-if-changed=build.rs"); 5 println!("cargo:rustc-check-cfg=cfg(assert_no_panic)"); 6 println!("cargo:rustc-check-cfg=cfg(feature, values(\"unstable\"))"); 7 8 println!("cargo:rustc-check-cfg=cfg(feature, values(\"checked\"))"); 9 10 #[allow(unexpected_cfgs)] 11 if !cfg!(feature = "checked") { 12 let lvl = env::var("OPT_LEVEL").unwrap(); 13 if lvl != "0" { 14 println!("cargo:rustc-cfg=assert_no_panic"); 15 } 16 } 17 } 18