Add a version banner with git revision and build metadata (echo --version, startup log, CTCP VERSION)

src/version.rs

@@ -0,0 +1,54 @@
+//! Build/version metadata, captured at compile time by `build.rs` and formatted
+//! for `echo --version`, the startup log, and the CTCP VERSION reply.
+
+pub const VERSION: &str = env!("CARGO_PKG_VERSION");
+pub const GIT_HASH: &str = env!("ECHO_GIT_HASH");
+pub const GIT_DIRTY: &str = env!("ECHO_GIT_DIRTY"); // "-dirty" or ""
+pub const COMMIT_DATE: &str = env!("ECHO_COMMIT_DATE");
+pub const RUSTC: &str = env!("ECHO_RUSTC");
+pub const TARGET: &str = env!("ECHO_TARGET");
+const BUILD_EPOCH: &str = env!("ECHO_BUILD_EPOCH");
+
+fn profile() -> &'static str {
+    if cfg!(debug_assertions) {
+        "debug"
+    } else {
+        "release"
+    }
+}
+
+/// The build time as "YYYY-MM-DD HH:MM:SS UTC".
+pub fn built() -> String {
+    echo_api::human_time(BUILD_EPOCH.parse().unwrap_or(0))
+}
+
+/// `git a1b2c3d4e5f6` (or `…-dirty`), the revision alone.
+pub fn revision() -> String {
+    format!("{GIT_HASH}{GIT_DIRTY}")
+}
+
+/// One compact line — for the CTCP VERSION reply and the startup log.
+/// `echo 0.0.1 (a1b2c3d4e5f6)`.
+pub fn short() -> String {
+    format!("echo {VERSION} ({})", revision())
+}
+
+/// The full multi-line banner for `echo --version`.
+pub fn banner() -> String {
+    let commit = if COMMIT_DATE.is_empty() {
+        String::new()
+    } else {
+        format!(" ({COMMIT_DATE})")
+    };
+    format!(
+        "echo \u{2014} federated IRC services\n  \
+         version:  {VERSION}\n  \
+         revision: {rev}{commit}\n  \
+         built:    {built} ({profile})\n  \
+         rustc:    {RUSTC}\n  \
+         target:   {TARGET}",
+        rev = revision(),
+        built = built(),
+        profile = profile(),
+    )
+}