Rocket/codegen/build.rs

//! This tiny build script ensures that rocket_codegen is not compiled with an
//! incompatible version of rust.

extern crate yansi;
extern crate version_check;

use yansi::Color::{Red, Yellow, Blue, White};
use version_check::{supports_features, is_min_version, is_min_date};

// Specifies the minimum nightly version needed to compile Rocket's codegen.
const MIN_DATE: &'static str = "2017-06-01";
const MIN_VERSION: &'static str = "1.19.0-nightly";

// Convenience macro for writing to stderr.
macro_rules! printerr {
    ($($arg:tt)*) => ({
        use std::io::prelude::*;
        write!(&mut ::std::io::stderr(), "{}\n", format_args!($($arg)*))
            .expect("Failed to write to stderr.")
    })
}

fn main() {
    let ok_channel = supports_features();
    let ok_version = is_min_version(MIN_VERSION);
    let ok_date = is_min_date(MIN_DATE);

    let print_version_err = |version: &str, date: &str| {
        printerr!("{} {}. {} {}.",
                  White.paint("Installed version is:"),
                  Yellow.paint(format!("{} ({})", version, date)),
                  White.paint("Minimum required:"),
                  Yellow.paint(format!("{} ({})", MIN_VERSION, MIN_DATE)));
    };

    match (ok_channel, ok_version, ok_date) {
        (Some(ok_channel), Some((ok_version, version)), Some((ok_date, date))) => {
            if !ok_channel {
                printerr!("{} {}",
                          Red.paint("Error:").bold(),
                          White.paint("Rocket requires a nightly or dev version of Rust."));
                print_version_err(&*version, &*date);
                printerr!("{}{}{}",
                          Blue.paint("See the getting started guide ("),
                          White.paint("https://rocket.rs/guide/getting-started/"),
                          Blue.paint(") for more information."));
                panic!("Aborting compilation due to incompatible compiler.")
            }

            if !ok_version || !ok_date {
                printerr!("{} {}",
                          Red.paint("Error:").bold(),
                          White.paint("Rocket codegen requires a more recent version of rustc."));
                printerr!("{}{}{}",
                          Blue.paint("Use `"),
                          White.paint("rustup update"),
                          Blue.paint("` or your preferred method to update Rust."));
                print_version_err(&*version, &*date);
                panic!("Aborting compilation due to incompatible compiler.")
            }
        },
        _ => {
            println!("cargo:warning={}", "Rocket was unable to check rustc compatibility.");
            println!("cargo:warning={}", "Build may fail due to incompatible rustc version.");
        }
    }
}