feat: Print the commit hash when passing --version to the gluon execu…

…table

repl/build.rs

@@ -0,0 +1,9 @@
+use std::process::Command;
+
+fn main() {
+    let output = Command::new("git").args(&["rev-parse", "HEAD"]).output().unwrap();
+    let git_hash = String::from_utf8(output.stdout).unwrap();
+    println!("cargo:rustc-env=GIT_HASH={}", git_hash);
+    // This is the closest thing to making sure we rebuild this every time a new commit is made
+    println!("cargo:rerun-if-changed=../.git/COMMIT_EDITMSG");
+}

repl/src/main.rs

@@ -88,10 +88,15 @@ fn fmt_stdio() -> Result<()> {
 }
 
 fn run() -> std::result::Result<(), Box<std::error::Error + Send + Sync>> {
-    const GLUON_VERSION: &'static str = env!("CARGO_PKG_VERSION");
 
     let matches = clap_app!(gluon =>
-        (version: GLUON_VERSION)
+        (version: crate_version!())
+        (long_version:
+            concat!(
+                crate_version!(), "\n",
+                "commit: ", env!("GIT_HASH")
+            )
+        )
         (about: "executes gluon programs")
         (@arg REPL: -i --interactive "Starts the repl")
         (@subcommand fmt =>