Add support for querying the program version

A user may be interested in understanding what version of the program is
running. With this change we enable clap's version printing feature to
emit program version and git SHA-1/tag, if present. We use the grev
crate for retrieving git version information.

CHANGELOG.md

@@ -1,5 +1,6 @@
 Unreleased
 ----------
+- Added support for `--version`/`-V` option to print program version
 - Bumped `zbus` dependency to `4.0`
 
 

Cargo.toml

@@ -34,9 +34,13 @@ codegen-units = 1
 incremental = false
 panic = "abort"
 
+[build-dependencies]
+anyhow = { version = "1.0.71", default-features = false, features = ["std"] }
+grev = { version = "0.1.3", default-features = false }
+
 [dependencies]
 anyhow = { version = "1.0.71", default-features = false, features = ["std"] }
-clap = {version = "4.1.4", features = ["derive"]}
+clap = { version = "4.1.4", features = ["derive"] }
 tokio = { version = "1.34", default-features = false, features = ["macros", "rt", "time"] }
 tracing = { version = "0.1", default-features = false, features = ["std"] }
 tracing-subscriber = { version = "0.3", default-features = false, features = ["ansi", "chrono", "env-filter", "fmt"] }

build.rs

@@ -0,0 +1,21 @@
+// Copyright (C) 2024 Daniel Mueller (deso@posteo.net)
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use anyhow::Result;
+
+use grev::git_revision_auto;
+
+
+fn main() -> Result<()> {
+  let dir = env!("CARGO_MANIFEST_DIR");
+  if let Some(git_rev) = git_revision_auto(dir)? {
+    println!(
+      "cargo:rustc-env=VERSION={} ({})",
+      env!("CARGO_PKG_VERSION"),
+      git_rev
+    );
+  } else {
+    println!("cargo:rustc-env=VERSION={}", env!("CARGO_PKG_VERSION"));
+  }
+  Ok(())
+}

src/main.rs

@@ -87,6 +87,7 @@ fn parse_duration(s: &str) -> Result<Duration> {
 /// A program/daemon sending notifications when the user should take a
 /// break from staring at the screen.
 #[derive(Debug, Parser)]
+#[clap(version = env!("VERSION"))]
 pub struct Args {
   /// The duration that, if the user has been "goggling" for this long,
   /// we post a notification.