feat(lsp): pass client_info on initialization

Pass client name ('helix') and client version (version / git hash)
to LSP server on initialization.

helix-lsp/build.rs

@@ -0,0 +1,22 @@
+use std::borrow::Cow;
+use std::process::Command;
+
+const VERSION: &str = include_str!("../VERSION");
+
+fn main() {
+    let git_hash = Command::new("git")
+        .args(["rev-parse", "HEAD"])
+        .output()
+        .ok()
+        .filter(|output| output.status.success())
+        .and_then(|x| String::from_utf8(x.stdout).ok());
+
+    let version: Cow<_> = match git_hash {
+        Some(git_hash) => format!("{} ({})", VERSION, &git_hash[..8]).into(),
+        None => VERSION.into(),
+    };
+
+    println!("cargo:rerun-if-changed=../VERSION");
+
+    println!("cargo:rustc-env=VERSION_AND_GIT_HASH={}", version);
+}

helix-lsp/src/client.rs

@@ -376,7 +376,10 @@ impl Client {
                 ..Default::default()
             },
             trace: None,
-            client_info: None,
+            client_info: Some(lsp::ClientInfo {
+                name: String::from("helix"),
+                version: Some(String::from(env!("VERSION_AND_GIT_HASH"))),
+            }),
             locale: None, // TODO
         };