fix build of build.rs

[matthiaskrgr]

No description provided.

[mati865]

It shouldn't be required at all, Clippy is 2018 crate already

[matthiaskrgr]

I know.
Maybe there's a bug of how build.rs is handled with editions?

I was able to have

#![feature(rust_2018_preview)]
#![warn(rust_2018_idioms)]

extern crate ansi_term;
extern crate rustc_version;

use ansi_term::Colour::Red;
use rustc_version::{version_meta, version_meta_for, Channel, Version, VersionMeta};
use std::env;

without triggering any warnings.

[mati865]

@matthiaskrgr does it work if you add #![feature(rust_2018_preview)] and remove all extern crate...?

[matthiaskrgr]

Nope, the build errors return when I do that.

[mati865]

I think you should reported it to rust/cargo (if it's not reported already) and add comment with link to the issue. It's a workaround and somebody could remove it prematurely.

[phansch]

Going ahead and closing this because the cargo PR has been merged. We just need to wait for cargo to be updated in rustc and the following nightly.