1 use std::env; 2 use std::process::Command; 3 use std::str; 4 5 fn main() { 6 /* 7 * If `core::ffi::c_void` exists, libc can just re-export it. Otherwise, it 8 * must define an incompatible type to retain backwards-compatibility. 9 */ 10 if rustc_minor_version().expect("Failed to get rustc version") >= 30 { 11 println!("cargo:rustc-cfg=core_cvoid"); 12 } 13 } 14 15 fn rustc_minor_version() -> Option<u32> { 16 macro_rules! otry { 17 ($e:expr) => { 18 match $e { 19 Some(e) => e, 20 None => return None, 21 } 22 }; 23 } 24 25 let rustc = otry!(env::var_os("RUSTC")); 26 let output = otry!(Command::new(rustc).arg("--version").output().ok()); 27 let version = otry!(str::from_utf8(&output.stdout).ok()); 28 let mut pieces = version.split('.'); 29 30 if pieces.next() != Some("rustc 1") { 31 return None; 32 } 33 34 otry!(pieces.next()).parse().ok() 35 } 36