4 files changed, 35 insertions, 4 deletions

diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 6c311648a..21acfe644 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -130,6 +130,7 @@ pub struct ClientCapsConfig {
     pub code_action_group: bool,
     pub resolve_code_action: bool,
     pub hover_actions: bool,
+    pub status_notification: bool,
 }
 
 impl Config {
@@ -365,6 +366,7 @@ impl Config {
             self.client_caps.code_action_group = get_bool("codeActionGroup");
             self.client_caps.resolve_code_action = get_bool("resolveCodeAction");
             self.client_caps.hover_actions = get_bool("hoverActions");
+            self.client_caps.status_notification = get_bool("statusNotification");
         }
     }
 }
diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index b7b4edf66..5e9cae3f8 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -31,6 +31,7 @@ use crate::{
 pub(crate) enum Status {
     Loading,
     Ready,
+    Invalid,
 }
 
 impl Default for Status {
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index 82207bbb8..d225ad5ff 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -3,7 +3,7 @@
 use std::{collections::HashMap, path::PathBuf};
 
 use lsp_types::request::Request;
-use lsp_types::{Position, Range, TextDocumentIdentifier};
+use lsp_types::{notification::Notification, Position, Range, TextDocumentIdentifier};
 use serde::{Deserialize, Serialize};
 
 pub enum AnalyzerStatus {}
@@ -208,6 +208,22 @@ pub struct SsrParams {
     pub parse_only: bool,
 }
 
+pub enum StatusNotification {}
+
+#[serde(rename_all = "camelCase")]
+#[derive(Serialize, Deserialize)]
+pub enum Status {
+    Loading,
+    Ready,
+    NeedsReload,
+    Invalid,
+}
+
+impl Notification for StatusNotification {
+    type Params = Status;
+    const METHOD: &'static str = "rust-analyzer/status";
+}
+
 pub enum CodeActionRequest {}
 
 impl Request for CodeActionRequest {
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index e03038b25..a5a8c17a0 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -169,16 +169,16 @@ impl GlobalState {
                 }
                 vfs::loader::Message::Progress { n_total, n_done } => {
                     if n_total == 0 {
-                        self.status = Status::Ready;
+                        self.transition(Status::Invalid);
                     } else {
                         let state = if n_done == 0 {
-                            self.status = Status::Loading;
+                            self.transition(Status::Loading);
                             Progress::Begin
                         } else if n_done < n_total {
                             Progress::Report
                         } else {
                             assert_eq!(n_done, n_total);
-                            self.status = Status::Ready;
+                            self.transition(Status::Ready);
                             Progress::End
                         };
                         self.report_progress(
@@ -274,6 +274,18 @@ impl GlobalState {
         Ok(())
     }
 
+    fn transition(&mut self, new_status: Status) {
+        self.status = Status::Ready;
+        if self.config.client_caps.status_notification {
+            let lsp_status = match new_status {
+                Status::Loading => lsp_ext::Status::Loading,
+                Status::Ready => lsp_ext::Status::Ready,
+                Status::Invalid => lsp_ext::Status::Invalid,
+            };
+            self.send_notification::<lsp_ext::StatusNotification>(lsp_status);
+        }
+    }
+
     fn on_request(&mut self, request_received: Instant, req: Request) -> Result<()> {
         self.register_request(&req, request_received);