Include git commit hash as string into Rust program

Question

I host a Rust project in git repository and I want to make it print the version on some command. How can I include the version into the program? I thought that the build script

Answer 1

There is already an existing crate vergen that can calculate the git commit in the build script. As @DK's answer described, the build script cannot modify environment variable before Rust 1.19, so vergen still works by writing the result into OUT_DIR (i.e. vergen still won't solve OP's question, but it should be easier to use).

---

Usage:

# Cargo.toml
...
[build-dependencies]
vergen = "0.1"

// build.rs
extern crate vergen;
use vergen::*;
fn main() {
    vergen(SHORT_SHA | COMMIT_DATE).unwrap();
}

mod version {
    include!(concat!(env!("OUT_DIR"), "/version.rs"));
}
fn main() {
    println!("commit: {} {}", version::commit_date(), version::short_sha());
    // output something like:
    //        commit: 2017-05-03 a29c7e5
}