add git commit hash to debug window

voxygen/build.rs

@@ -0,0 +1,14 @@
+use std::process::Command;
+
+fn main() {
+    match Command::new("git")
+        .args(&["rev-parse", "--short", "HEAD"])
+        .output()
+    {
+        Ok(output) => match String::from_utf8(output.stdout) {
+            Ok(hash) => println!("cargo:rustc-env=GIT_HASH={}", hash),
+            Err(e) => println!("failed to convert git output to UTF-8: {}", e),
+        },
+        Err(e) => println!("failed to retrieve current git commit hash: {}", e),
+    }
+}

voxygen/src/hud/mod.rs

@@ -305,7 +305,11 @@ impl Hud {
     ) -> Vec<Event> {
         let mut events = Vec::new();
         let ref mut ui_widgets = self.ui.set_widgets();
-        let version = env!("CARGO_PKG_VERSION");
+
+        let version = match std::env::var("GIT_HASH") {
+            Ok(hash) => format!("{}-{}", env!("CARGO_PKG_VERSION"), hash),
+            Err(_) => env!("CARGO_PKG_VERSION").to_owned(),
+        };
 
         // Don't show anything if the UI is toggled off.
         if !self.show.ui {
@@ -421,7 +425,7 @@ impl Hud {
         // Display debug window.
         if self.show.debug {
             // Alpha Version
-            Text::new(version)
+            Text::new(&version)
                 .top_left_with_margins_on(ui_widgets.window, 5.0, 5.0)
                 .font_size(14)
                 .font_id(self.fonts.opensans)