4 files changed, 26 insertions, 4 deletions

diff --git a/crates/ra_cargo_watch/src/lib.rs b/crates/ra_cargo_watch/src/lib.rs
index 9bc0fd405..cb0856aa4 100644
--- a/crates/ra_cargo_watch/src/lib.rs
+++ b/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 {
diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index 121ddfd1f..c0175c726 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -132,8 +132,20 @@ impl WorldState {
         change.set_crate_graph(crate_graph);
 
         // FIXME: Figure out the multi-workspace situation
-        let check_watcher =
-            CheckWatcher::new(&options.cargo_watch, folder_roots.first().cloned().unwrap());
+        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);
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 1b3c246c7..1832c101f 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -21,7 +21,7 @@ use crate::Result;
 pub struct CargoWorkspace {
     packages: Arena<Package, PackageData>,
     targets: Arena<Target, TargetData>,
-    pub(crate) workspace_root: PathBuf,
+    workspace_root: PathBuf,
 }
 
 #[derive(Deserialize, Clone, Debug, PartialEq, Eq)]
@@ -225,4 +225,8 @@ impl CargoWorkspace {
     pub fn target_by_root(&self, root: &Path) -> Option<Target> {
         self.packages().filter_map(|pkg| pkg.targets(self).find(|it| it.root(self) == root)).next()
     }
+
+    pub fn workspace_root(&self) -> &Path {
+        &self.workspace_root
+    }
 }
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index b7f6a9b57..6a104e6f2 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -333,7 +333,7 @@ impl ProjectWorkspace {
     pub fn workspace_root_for(&self, path: &Path) -> Option<&Path> {
         match self {
             ProjectWorkspace::Cargo { cargo, .. } => {
-                Some(cargo.workspace_root.as_ref()).filter(|root| path.starts_with(root))
+                Some(cargo.workspace_root()).filter(|root| path.starts_with(root))
             }
             ProjectWorkspace::Json { project: JsonProject { roots, .. } } => roots
                 .iter()