main()1 fn main() { 2 // If "std" is explicitly requested, don't bother probing the target for it. 3 match std::env::var_os("CARGO_FEATURE_STD") { 4 Some(_) => autocfg::emit("has_std"), 5 None => autocfg::new().emit_sysroot_crate("std"), 6 } 7 autocfg::rerun_path("build.rs"); 8 } 9