build.rs

fn main() {
    write_git_version();
}
fn write_git_version() {
    let tag = git(&["describe", "--exact-match", "--tags", "HEAD"]);
    let version = tag.unwrap_or_else(|| {
        let commit = git(&["rev-parse", "--short=7", "HEAD"])
            .expect("`git` was not successful, are you in the right directory?");
        let most_recent_tag = git(&["describe", "--tags", "--abbrev=0", "HEAD"]).unwrap();
        format!("{}-dev ({})", most_recent_tag, commit)
    });
    println!("cargo:rustc-env=RCC_GIT_REV={}", version);
    println!("cargo:rerun-if-changed=.git/HEAD");
}

fn git(args: &[&str]) -> Option<String> {
    use std::process::Command;
    let output = Command::new("git")
        .args(args)
        .output()
        .expect("failed to run `git`, is it installed?");
    if output.status.success() {
        Some(String::from_utf8(output.stdout).unwrap().trim().to_string())
    } else {
        None
    }
}