readable-perms/build.rs

extern crate rustc_version;
use rustc_version::{version, version_meta, Channel};

fn main() {
    // Assert we haven't travelled back in time
    assert!(version().unwrap().major >= 1);

    // Set cfg flags depending on release channel
    match version_meta().unwrap().channel {
        Channel::Stable => {
            println!("cargo:rustc-cfg=stable");
        }
        Channel::Beta => {
            println!("cargo:rustc-cfg=beta");
        }
        Channel::Nightly => {
            println!("cargo:rustc-cfg=nightly");
        }
        Channel::Dev => {
            println!("cargo:rustc-cfg=dev");
        }
    }
}