| use std::env; |
| use std::process::Command; |
| use std::str::FromStr; |
| |
| fn main() { |
| let minor = match rustc_minor_version() { |
| Some(minor) => minor, |
| None => return, |
| }; |
| if minor >= 22 { |
| println!("cargo:rustc-cfg=derive_copy"); |
| } |
| if minor >= 28 { |
| println!("cargo:rustc-cfg=repr_transparent"); |
| } |
| if minor >= 36 { |
| println!("cargo:rustc-cfg=native_uninit"); |
| } |
| |
| } |
| |
| fn rustc_minor_version() -> Option<u32> { |
| let rustc = env::var_os("RUSTC"); |
| |
| let output = rustc.and_then(|rustc| { |
| Command::new(rustc).arg("--version").output().ok() |
| }); |
| |
| let version = output.and_then(|output| { |
| String::from_utf8(output.stdout).ok() |
| }); |
| |
| let version = if let Some(version) = version { |
| version |
| } else { |
| return None; |
| }; |
| |
| let mut pieces = version.split('.'); |
| if pieces.next() != Some("rustc 1") { |
| return None; |
| } |
| |
| let next = match pieces.next() { |
| Some(next) => next, |
| None => return None, |
| }; |
| |
| u32::from_str(next).ok() |
| } |