Add Git information to cargo-gpu's --version CLI subcommand

crates/cargo-gpu/build.rs

@@ -1,12 +1,39 @@
 //! cargo-gpu build script.
 
+use std::ffi::OsStr;
+
 fn main() {
-    let git_hash = std::process::Command::new("git")
-        .args(["rev-parse", "HEAD"])
-        .output()
-        .map_or_else(
-            |_| "unknown".to_owned(),
-            |output| String::from_utf8(output.stdout).unwrap_or_else(|_| "unknown".to_owned()),
-        );
+    let git_directory = invoke_git(["rev-parse", "--git-dir"]);
+    println!("cargo:rerun-if-changed={git_directory}/HEAD");
+    println!("cargo:rerun-if-changed={git_directory}/packed-refs");
+    if let Ok(git_head) = std::fs::read_to_string(format!("{git_directory}/HEAD"))
+        && let Some(git_ref) = git_head.strip_prefix("ref: ")
+    {
+        println!("cargo:rerun-if-changed={git_directory}/{}", git_ref.trim());
+    }
+
+    let git_hash = invoke_git(["rev-parse", "HEAD"]);
     println!("cargo:rustc-env=GIT_HASH={git_hash}");
+
+    let git_date = invoke_git([
+        "show",
+        "-s",
+        "--format=%cd",
+        "--date=format:%Y-%m-%d",
+        "HEAD",
+    ]);
+    println!("cargo:rustc-env=GIT_DATE={git_date}");
+}
+
+fn invoke_git<I, S>(args: I) -> String
+where
+    I: IntoIterator<Item = S>,
+    S: AsRef<OsStr>,
+{
+    std::process::Command::new("git")
+        .args(args)
+        .output()
+        .ok()
+        .and_then(|output| String::from_utf8(output.stdout).ok())
+        .unwrap_or_else(|| "unknown".to_owned())
 }

crates/cargo-gpu/src/lib.rs

@@ -153,7 +153,7 @@ impl Command {
 
 /// the Cli struct representing the main cli
 #[derive(clap::Parser)]
-#[clap(author, version, about, subcommand_required = true)]
+#[clap(author, version, long_version = concat!(env!("CARGO_PKG_VERSION"), " (", env!("GIT_HASH"), "; ", env!("GIT_DATE"), ")"), about, subcommand_required = true)]
 #[non_exhaustive]
 pub struct Cli {
     /// The command to run.