use std::str;

use std::str::{self, FromStr};

    if compiler.nightly {

    if compiler.minor >= 40 && compiler.nightly {

    minor: u32,

    let rustc = match env::var_os("RUSTC") {
        Some(rustc) => rustc,
        None => return None,
    };
    let output = match Command::new(rustc).arg("--version").output() {
        Ok(output) => output,
        Err(_) => return None,
    };

    let rustc = env::var_os("RUSTC")?;
    let output = Command::new(rustc).arg("--version").output().ok()?;
    let version = str::from_utf8(&output.stdout).ok()?;

    let version = match str::from_utf8(&output.stdout) {
        Ok(version) => version,
        Err(_) => return None,
    };

    let mut pieces = version.split('.');
    if pieces.next() != Some("rustc 1") {
        return None;
    }

    Some(Compiler {
        nightly: version.contains("nightly") || version.contains("dev"),
    })

    let next = pieces.next()?;
    let minor = u32::from_str(next).ok()?;
    let nightly = version.contains("nightly") || version.contains("dev");
    Some(Compiler { minor, nightly })