Include commits since tag in langserver version number

src/langserver/build.rs

@@ -11,8 +11,9 @@ fn main() {
     let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
     let mut f = File::create(&out_dir.join("build-info.txt")).unwrap();
 
-    if let Ok(commit) = read_commit() {
-        writeln!(f, "commit: {}", commit).unwrap();
+    match read_commit() {
+        Ok(commit) => writeln!(f, "commit: {}", commit).unwrap(),
+        Err(err) => println!("cargo:warning=Failed to fetch commit info: {}", err)
     }
     writeln!(f, "build date: {}", chrono::Utc::today()).unwrap();
 
@@ -31,6 +32,31 @@ fn main() {
 
 fn read_commit() -> Result<String, git2::Error> {
     let repo = git2::Repository::discover(".")?;
-    let hash = repo.head()?.peel_to_commit()?.id().to_string();
-    Ok(hash)
+    let head = repo.head()?.peel_to_commit()?.id();
+
+    let mut all_tags = Vec::new();
+    repo.tag_foreach(|oid, _| { all_tags.push(oid); true })?;
+
+    let mut best = None;
+    for tag_id in all_tags {
+        let tag_commit = repo.find_tag(tag_id)?.as_object().peel_to_commit()?.id();
+        let (ahead, behind) = repo.graph_ahead_behind(head, tag_commit)?;
+        if behind == 0 {
+            match best {
+                None => best = Some(ahead),
+                Some(prev) if ahead < prev => best = Some(ahead),
+                _ => {}
+            }
+        }
+        if ahead == 0 {
+            break;
+        }
+    }
+
+    match best {
+        None | Some(0) => {}
+        Some(ahead) => println!("cargo:rustc-env=CARGO_PKG_VERSION={}+{}", std::env::var("CARGO_PKG_VERSION").unwrap(), ahead),
+    }
+
+    Ok(head.to_string())
 }