1 use std::env; 2 use std::ffi::OsString; 3 use std::process; 4 main()5fn main() { 6 println!("cargo:rerun-if-changed=build.rs"); 7 8 println!("cargo:rustc-check-cfg=cfg(exhaustive)"); 9 println!("cargo:rustc-check-cfg=cfg(prettyplease_debug)"); 10 println!("cargo:rustc-check-cfg=cfg(prettyplease_debug_indent)"); 11 12 let pkg_version = cargo_env_var("CARGO_PKG_VERSION"); 13 println!("cargo:VERSION={}", pkg_version.to_str().unwrap()); 14 } 15 cargo_env_var(key: &str) -> OsString16fn cargo_env_var(key: &str) -> OsString { 17 env::var_os(key).unwrap_or_else(|| { 18 eprintln!("Environment variable ${key} is not set during execution of build script"); 19 process::exit(1); 20 }) 21 } 22