Include git rev in the version number

cranelift/codegen/build.rs

@@ -17,6 +17,7 @@
 use cranelift_codegen_meta as meta;
 
 use std::env;
+use std::io::Read;
 use std::process;
 use std::time::Instant;
 
@@ -97,4 +98,40 @@ fn main() {
         )
         .unwrap()
     }
+
+    let pkg_version = env::var("CARGO_PKG_VERSION").unwrap();
+    let mut cmd = std::process::Command::new("git");
+    cmd.arg("rev-parse")
+        .arg("HEAD")
+        .stdout(std::process::Stdio::piped())
+        .current_dir(env::var("CARGO_MANIFEST_DIR").unwrap());
+    let version = if let Ok(mut child) = cmd.spawn() {
+        let mut git_rev = String::new();
+        child
+            .stdout
+            .as_mut()
+            .unwrap()
+            .read_to_string(&mut git_rev)
+            .unwrap();
+        let status = child.wait().unwrap();
+        if status.success() {
+            let git_rev = git_rev.trim().chars().take(9).collect::<String>();
+            format!("{}-{}", pkg_version, git_rev)
+        } else {
+            // not a git repo
+            pkg_version
+        }
+    } else {
+        // git not available
+        pkg_version
+    };
+    std::fs::write(
+        std::path::Path::new(&out_dir).join("version.rs"),
+        format!(
+            "/// Version number of this crate. \n\
+            pub const VERSION: &str = \"{}\";",
+            version
+        ),
+    )
+    .unwrap();
 }

cranelift/codegen/src/lib.rs

@@ -121,5 +121,4 @@ mod souper_harvest;
 
 pub use crate::result::{CodegenError, CodegenResult};
 
-/// Version number of this crate.
+include!(concat!(env!("OUT_DIR"), "/version.rs"));
-pub const VERSION: &str = env!("CARGO_PKG_VERSION");