allow including extra info in --version output

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/clap.rs

@@ -4,9 +4,23 @@ use std::path::PathBuf;
 
 use clap::Parser;
 
+/// Returns the current version of the crate with extra info if supplied
+///
+/// Set the environment variable `CONDUIT_VERSION_EXTRA` to any UTF-8 string to
+/// include it in parenthesis after the SemVer version. A common value are git
+/// commit hashes.
+fn version() -> String {
+	let cargo_pkg_version = env!("CARGO_PKG_VERSION");
+
+	match option_env!("CONDUIT_VERSION_EXTRA") {
+		Some(x) => format!("{} ({})", cargo_pkg_version, x),
+		None => cargo_pkg_version.to_owned(),
+	}
+}
+
 /// Commandline arguments
 #[derive(Parser, Debug)]
-#[clap(version, about, long_about = None)]
+#[clap(version = version(), about, long_about = None)]
 pub struct Args {
 	#[arg(short, long)]
 	/// Optional argument to the path of a conduwuit config TOML file