4 files changed, 51 insertions, 7 deletions

diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index 5e9cae3f8..640b3959d 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -32,6 +32,7 @@ pub(crate) enum Status {
     Loading,
     Ready,
     Invalid,
+    NeedsReload,
 }
 
 impl Default for Status {
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index a5a8c17a0..d4d18a808 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -111,6 +111,35 @@ impl GlobalState {
     }
 
     fn run(mut self, inbox: Receiver<lsp_server::Message>) -> Result<()> {
+        let registration_options = lsp_types::TextDocumentRegistrationOptions {
+            document_selector: Some(vec![
+                lsp_types::DocumentFilter {
+                    language: None,
+                    scheme: None,
+                    pattern: Some("**/*.rs".into()),
+                },
+                lsp_types::DocumentFilter {
+                    language: None,
+                    scheme: None,
+                    pattern: Some("**/Cargo.toml".into()),
+                },
+                lsp_types::DocumentFilter {
+                    language: None,
+                    scheme: None,
+                    pattern: Some("**/Cargo.lock".into()),
+                },
+            ]),
+        };
+        let registration = lsp_types::Registration {
+            id: "textDocument/didSave".to_string(),
+            method: "textDocument/didSave".to_string(),
+            register_options: Some(serde_json::to_value(registration_options).unwrap()),
+        };
+        self.send_request::<lsp_types::request::RegisterCapability>(
+            lsp_types::RegistrationParams { registrations: vec![registration] },
+            |_, _| (),
+        );
+
         self.reload();
 
         while let Some(event) = self.next_event(&inbox) {
@@ -281,6 +310,7 @@ impl GlobalState {
                 Status::Loading => lsp_ext::Status::Loading,
                 Status::Ready => lsp_ext::Status::Ready,
                 Status::Invalid => lsp_ext::Status::Invalid,
+                Status::NeedsReload => lsp_ext::Status::NeedsReload,
             };
             self.send_notification::<lsp_ext::StatusNotification>(lsp_status);
         }
@@ -395,10 +425,16 @@ impl GlobalState {
                 );
                 Ok(())
             })?
-            .on::<lsp_types::notification::DidSaveTextDocument>(|this, _params| {
+            .on::<lsp_types::notification::DidSaveTextDocument>(|this, params| {
                 if let Some(flycheck) = &this.flycheck {
                     flycheck.handle.update();
                 }
+                let uri = params.text_document.uri.as_str();
+                if uri.ends_with("Cargo.toml") || uri.ends_with("Cargo.lock") {
+                    if matches!(this.status, Status::Ready | Status::Invalid) {
+                        this.transition(Status::NeedsReload);
+                    }
+                }
                 Ok(())
             })?
             .on::<lsp_types::notification::DidChangeConfiguration>(|this, _params| {
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index 0c1fd1b8b..523b04b97 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -78,7 +78,7 @@ impl GlobalState {
                     .collect(),
             };
             let registration = lsp_types::Registration {
-                id: "file-watcher".to_string(),
+                id: "workspace/didChangeWatchedFiles".to_string(),
                 method: "workspace/didChangeWatchedFiles".to_string(),
                 register_options: Some(serde_json::to_value(registration_options).unwrap()),
             };
diff --git a/crates/rust-analyzer/tests/heavy_tests/support.rs b/crates/rust-analyzer/tests/heavy_tests/support.rs
index 49f194f7e..7bf687794 100644
--- a/crates/rust-analyzer/tests/heavy_tests/support.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/support.rs
@@ -176,12 +176,19 @@ impl Server {
         while let Some(msg) = self.recv() {
             match msg {
                 Message::Request(req) => {
-                    if req.method != "window/workDoneProgress/create"
-                        && !(req.method == "client/registerCapability"
-                            && req.params.to_string().contains("workspace/didChangeWatchedFiles"))
-                    {
-                        panic!("unexpected request: {:?}", req)
+                    if req.method == "window/workDoneProgress/create" {
+                        continue;
                     }
+                    if req.method == "client/registerCapability" {
+                        let params = req.params.to_string();
+                        if ["workspace/didChangeWatchedFiles", "textDocument/didSave"]
+                            .iter()
+                            .any(|&it| params.contains(it))
+                        {
+                            continue;
+                        }
+                    }
+                    panic!("unexpected request: {:?}", req)
                 }
                 Message::Notification(_) => (),
                 Message::Response(res) => {