clap::crate_version!

macro_rules! crate_version {
    () => {
        format!("{}.{}.{}{}",
            env!("CARGO_PKG_VERSION_MAJOR"),
            env!("CARGO_PKG_VERSION_MINOR"),
            env!("CARGO_PKG_VERSION_PATCH"),
            option_env!("CARGO_PKG_VERSION_PRE").unwrap_or(""))
    }
}

Allows you pull the version for an from your Cargo.toml as MAJOR.MINOR.PATCH_PKGVERSION_PRE

Example

    let m = App::new("app")
                .version(&crate_version!()[..])
                .get_matches();