1 files changed, 29 insertions, 1 deletions

diff --git a/crates/rust-analyzer/build.rs b/crates/rust-analyzer/build.rs
index 05f9772c0..d4b010c04 100644
--- a/crates/rust-analyzer/build.rs
+++ b/crates/rust-analyzer/build.rs
@@ -1,12 +1,40 @@
 //! Just embed git-hash to `--version`
 
-use std::process::Command;
+use std::{env, path::PathBuf, process::Command};
 
 fn main() {
+    set_rerun();
+
     let rev = rev().unwrap_or_else(|| "???????".to_string());
     println!("cargo:rustc-env=REV={}", rev)
 }
 
+fn set_rerun() {
+    let mut manifest_dir = PathBuf::from(
+        env::var("CARGO_MANIFEST_DIR").expect("`CARGO_MANIFEST_DIR` is always set by cargo."),
+    );
+
+    while manifest_dir.parent().is_some() {
+        if manifest_dir.join(".git/HEAD").exists() {
+            let git_dir = manifest_dir.join(".git");
+
+            println!("cargo:rerun-if-changed={}", git_dir.join("HEAD").display());
+            // current branch ref
+            if let Ok(output) =
+                Command::new("git").args(&["rev-parse", "--symbolic-full-name", "HEAD"]).output()
+            {
+                if let Ok(ref_link) = String::from_utf8(output.stdout) {
+                    println!("cargo:rerun-if-changed={}", git_dir.join(ref_link).display());
+                }
+            }
+            return;
+        }
+
+        manifest_dir.pop();
+    }
+    println!("cargo:warning=Could not find `.git/HEAD` from manifest dir!");
+}
+
 fn rev() -> Option<String> {
     let output = Command::new("git").args(&["rev-parse", "HEAD"]).output().ok()?;
     let stdout = String::from_utf8(output.stdout).ok()?;