Disable cargo checking in workspaces with no cargo projects

Author: kiljacken

crates/ra_cargo_watch/src/lib.rs

@@ -58,6 +58,12 @@ impl CheckWatcher {
         CheckWatcher { task_recv, cmd_send: Some(cmd_send), handle: Some(handle), shared }
     }
 
+    /// Returns a CheckWatcher that doesn't actually do anything
+    pub fn dummy() -> CheckWatcher {
+        let shared = Arc::new(RwLock::new(CheckWatcherSharedState::new()));
+        CheckWatcher { task_recv: never(), cmd_send: None, handle: None, shared }
+    }
+
     /// Schedule a re-start of the cargo check worker.
     pub fn update(&self) {
         if let Some(cmd_send) = &self.cmd_send {

crates/ra_lsp_server/src/world.rs

@@ -132,20 +132,20 @@ impl WorldState {
         change.set_crate_graph(crate_graph);
 
         // FIXME: Figure out the multi-workspace situation
-        let check_watcher = {
-            let first_workspace = workspaces.first().unwrap();
-            let cargo_project_root = match first_workspace {
-                ProjectWorkspace::Cargo { cargo, .. } => cargo.workspace_root().to_path_buf(),
-                ProjectWorkspace::Json { .. } => {
-                    log::warn!(
-                        "Cargo check watching only supported for cargo workspaces, disabling"
-                    );
-                    options.cargo_watch.enable = false;
-                    PathBuf::new()
-                }
-            };
-            CheckWatcher::new(&options.cargo_watch, cargo_project_root)
-        };
+        let check_watcher = workspaces
+            .iter()
+            .find_map(|w| match w {
+                ProjectWorkspace::Cargo { cargo, .. } => Some(cargo),
+                ProjectWorkspace::Json { .. } => None,
+            })
+            .map(|cargo| {
+                let cargo_project_root = cargo.workspace_root().to_path_buf();
+                CheckWatcher::new(&options.cargo_watch, cargo_project_root)
+            })
+            .unwrap_or_else(|| {
+                log::warn!("Cargo check watching only supported for cargo workspaces, disabling");
+                CheckWatcher::dummy()
+            });
 
         let mut analysis_host = AnalysisHost::new(lru_capacity, feature_flags);
         analysis_host.apply_change(change);