optional git

build.rs

@@ -3,13 +3,13 @@ use std::{env, process::Command};
 #[allow(clippy::disallowed_macros)] // for println!
 fn main() {
     lalrpop::process_root().unwrap();
-    let output = Command::new("git")
+    let git_hash = Command::new("git")
         .args(["rev-parse", "--short", "HEAD"])
         .output()
-        .unwrap();
-    let git_hash = String::from_utf8(output.stdout).unwrap();
+        .map(|output| String::from_utf8(output.stdout).unwrap_or_default())
+        .unwrap_or_default();
     let build_date = chrono::Utc::now().format("%Y-%m-%d");
     let version = env::var("CARGO_PKG_VERSION").unwrap();
-    let full_version = format!("{}_{}_{}", version, build_date, git_hash);
+    let full_version = format!("{}_{}{}", version, build_date, git_hash);
     println!("cargo:rustc-env=FULL_VERSION={}", full_version);
 }