1 extern crate autocfg; 2 main()3 fn main() { 4 let ac = autocfg::new(); 5 // Allows `#[cfg(rustc_1_63)]` to be used in code 6 ac.emit_rustc_version(1, 63); 7 8 // Re-run if this file changes 9 autocfg::rerun_path("build.rs"); 10 } 11