version: show echoircd-<major> (5) in 002/004/351 and enrich RPL_VERSION with build/toolchain provenance

build.rs

@@ -0,0 +1,42 @@
+use std::process::Command;
+
+// Capture build provenance (git rev/date, toolchain, target) into env vars the
+// crate reads via env! for the VERSION reply. Always emits every var, with an
+// "unknown" fallback, so a non-git build (e.g. a source tarball) still compiles.
+fn main() {
+    println!("cargo:rerun-if-changed=.git/HEAD");
+    println!("cargo:rerun-if-changed=.git/index");
+
+    let git = |args: &[&str]| {
+        Command::new("git")
+            .args(args)
+            .output()
+            .ok()
+            .filter(|o| o.status.success())
+            .map(|o| String::from_utf8_lossy(&o.stdout).trim().to_string())
+            .filter(|s| !s.is_empty())
+    };
+
+    let hash = git(&["rev-parse", "--short=7", "HEAD"]).unwrap_or_else(|| "unknown".into());
+    let dirty = match git(&["status", "--porcelain", "--untracked-files=no"]) {
+        Some(s) if !s.is_empty() => "-dirty",
+        _ => "",
+    };
+    let date = git(&["log", "-1", "--format=%cd", "--date=short"]).unwrap_or_else(|| "unknown".into());
+
+    let rustc = Command::new(std::env::var("RUSTC").unwrap_or_else(|_| "rustc".into()))
+        .arg("--version")
+        .output()
+        .ok()
+        .map(|o| String::from_utf8_lossy(&o.stdout).trim().to_string())
+        .and_then(|s| s.split_whitespace().nth(1).map(str::to_string))
+        .unwrap_or_else(|| "unknown".into());
+
+    let target = std::env::var("TARGET").unwrap_or_else(|_| "unknown".into());
+
+    println!("cargo:rustc-env=ECHOIRCD_GIT_HASH={hash}");
+    println!("cargo:rustc-env=ECHOIRCD_GIT_DIRTY={dirty}");
+    println!("cargo:rustc-env=ECHOIRCD_COMMIT_DATE={date}");
+    println!("cargo:rustc-env=ECHOIRCD_RUSTC={rustc}");
+    println!("cargo:rustc-env=ECHOIRCD_TARGET={target}");
+}