6 files changed, 61 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()?;
diff --git a/docs/user/features.md b/docs/user/features.md
index 309d2775d..a00fa35da 100644
--- a/docs/user/features.md
+++ b/docs/user/features.md
@@ -89,6 +89,10 @@ Shows the full macro expansion of the macro at current cursor.
 
 Shows internal statistic about memory usage of rust-analyzer
 
+#### Show RA Version
+
+Show current rust-analyzer version
+
 #### Run garbage collection
 
 Manually triggers GC
diff --git a/editors/code/package.json b/editors/code/package.json
index c498c14b4..72befe2b6 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -131,6 +131,11 @@
                 "command": "rust-analyzer.ssr",
                 "title": "Structural Search Replace",
                 "category": "Rust Analyzer"
+            },
+            {
+                "command": "rust-analyzer.serverVersion",
+                "title": "Show RA Version",
+                "category": "Rust Analyzer"
             }
         ],
         "keybindings": [
diff --git a/editors/code/src/commands/index.ts b/editors/code/src/commands/index.ts
index bebd99ca9..839245f48 100644
--- a/editors/code/src/commands/index.ts
+++ b/editors/code/src/commands/index.ts
@@ -13,6 +13,7 @@ export * from './syntax_tree';
 export * from './expand_macro';
 export * from './runnables';
 export * from './ssr';
+export * from './server_version';
 
 export function collectGarbage(ctx: Ctx): Cmd {
     return async () => {
diff --git a/editors/code/src/commands/server_version.ts b/editors/code/src/commands/server_version.ts
new file mode 100644
index 000000000..421301b42
--- /dev/null
+++ b/editors/code/src/commands/server_version.ts
@@ -0,0 +1,21 @@
+import * as vscode from 'vscode';
+import { ensureServerBinary } from '../installation/server';
+import { Ctx, Cmd } from '../ctx';
+import { spawnSync } from 'child_process';
+
+export function serverVersion(ctx: Ctx): Cmd {
+    return async () => {
+        const binaryPath = await ensureServerBinary(ctx.config.serverSource);
+
+        if (binaryPath == null) {
+            throw new Error(
+                "Rust Analyzer Language Server is not available. " +
+                "Please, ensure its [proper installation](https://rust-analyzer.github.io/manual.html#installation)."
+            );
+        }
+
+        const version = spawnSync(binaryPath, ["--version"], { encoding: "utf8" }).stdout;
+        vscode.window.showInformationMessage('rust-analyzer version : ' + version);
+    };
+}
+
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index a22e0bc66..de19a44e5 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -55,6 +55,7 @@ export async function activate(context: vscode.ExtensionContext) {
     ctx.registerCommand('run', commands.run);
     ctx.registerCommand('onEnter', commands.onEnter);
     ctx.registerCommand('ssr', commands.ssr);
+    ctx.registerCommand('serverVersion', commands.serverVersion);
 
     // Internal commands which are invoked by the server.
     ctx.registerCommand('runSingle', commands.runSingle);