Avoid indexing the workspace for single-file support

crates/ruff_server/src/server.rs

@@ -551,6 +551,7 @@ impl Workspace {
     }
 
     /// Set the client settings for this workspace.
+    #[must_use]
     pub fn with_settings(mut self, settings: ClientSettings) -> Self {
         self.settings = Some(settings);
         self

crates/ruff_server/src/session/index.rs

@@ -286,6 +286,7 @@ impl Index {
             settings.ruff_settings = ruff_settings::RuffSettingsIndex::new(
                 root,
                 settings.client_settings.editor_settings(),
+                false,
             );
         }
     }
@@ -422,6 +423,7 @@ impl WorkspaceSettingsIndex {
         let workspace_settings_index = ruff_settings::RuffSettingsIndex::new(
             &workspace_path,
             client_settings.editor_settings(),
+            workspace.is_default(),
         );
 
         self.insert(

crates/ruff_server/src/session/index/ruff_settings.rs

@@ -100,13 +100,19 @@ impl RuffSettings {
 }
 
 impl RuffSettingsIndex {
-    pub(super) fn new(root: &Path, editor_settings: &ResolvedEditorSettings) -> Self {
+    pub(super) fn new(
+        root: &Path,
+        editor_settings: &ResolvedEditorSettings,
+        is_default_workspace: bool,
+    ) -> Self {
         let mut has_error = false;
         let mut index = BTreeMap::default();
         let mut respect_gitignore = None;
+        let should_skip_workspace = usize::from(!is_default_workspace);
 
-        // Add any settings from above the workspace root, excluding the workspace root itself.
-        for directory in root.ancestors().skip(1) {
+        // Add any settings from above the workspace root. The ones from the workspace root will be
+        // added only if it's not the default workspace.
+        for directory in root.ancestors().skip(should_skip_workspace) {
             match settings_toml(directory) {
                 Ok(Some(pyproject)) => {
                     match ruff_workspace::resolver::resolve_root_settings(
@@ -156,6 +162,18 @@ impl RuffSettingsIndex {
 
         let fallback = Arc::new(RuffSettings::fallback(editor_settings, root));
 
+        if is_default_workspace {
+            if has_error {
+                let root = root.display();
+                show_err_msg!(
+                    "Error while resolving settings from workspace {root}. \
+                    Please refer to the logs for more details.",
+                );
+            }
+
+            return RuffSettingsIndex { index, fallback };
+        }
+
         // Add any settings within the workspace itself
         let mut builder = WalkBuilder::new(root);
         builder.standard_filters(
@@ -266,7 +284,7 @@ impl RuffSettingsIndex {
             );
         }
 
-        Self {
+        RuffSettingsIndex {
             index: index.into_inner().unwrap(),
             fallback,
         }