1 extern crate autocfg; 2 main()3 fn main() { 4 // Normally, cargo will set `OUT_DIR` for build scripts. 5 let ac = autocfg::AutoCfg::with_dir("target").unwrap(); 6 for i in 3..8 { 7 ac.emit_has_type(&format!("i{}", 1 << i)); 8 } 9 } 10