use std::env; use std::process::Command; use std::str; fn main() { /* * If `core::ffi::c_void` exists, libc can just re-export it. Otherwise, it * must define an incompatible type to retain backwards-compatibility. */ if rustc_minor_version().expect("Failed to get rustc version") >= 31 { println!("cargo:rustc-cfg=core_cvoid"); } } fn rustc_minor_version() -> Option { macro_rules! otry { ($e:expr) => { match $e { Some(e) => e, None => return None, } }; } let rustc = otry!(env::var_os("RUSTC")); let output = otry!(Command::new(rustc).arg("--version").output().ok()); let version = otry!(str::from_utf8(&output.stdout).ok()); let mut pieces = version.split('.'); if pieces.next() != Some("rustc 1") { return None; } otry!(pieces.next()).parse().ok() }