4 files changed, 60 insertions, 51 deletions

diff --git a/crates/project_model/src/build_data.rs b/crates/project_model/src/build_data.rs
index f7050be4e..c2c87b207 100644
--- a/crates/project_model/src/build_data.rs
+++ b/crates/project_model/src/build_data.rs
@@ -52,7 +52,7 @@ pub struct BuildDataCollector {
     configs: FxHashMap<AbsPathBuf, BuildDataConfig>,
 }
 
-#[derive(Debug, Default, PartialEq, Eq)]
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct BuildDataResult {
     data: FxHashMap<AbsPathBuf, BuildDataMap>,
 }
diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index 8679c8599..b9be1e7b8 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -82,11 +82,16 @@ pub(crate) struct GlobalState {
     pub(crate) source_root_config: SourceRootConfig,
     pub(crate) proc_macro_client: Option<ProcMacroClient>,
 
+    /// For both `workspaces` and `workspace_build_data`, the field stores the
+    /// data we actually use, while the `OpQueue` stores the result of the last
+    /// fetch.
+    ///
+    /// If the fetch (partially) fails, we do not update the values.
     pub(crate) workspaces: Arc<Vec<ProjectWorkspace>>,
-    pub(crate) fetch_workspaces_queue: OpQueue<(), ()>,
-
+    pub(crate) fetch_workspaces_queue: OpQueue<(), Vec<anyhow::Result<ProjectWorkspace>>>,
     pub(crate) workspace_build_data: Option<BuildDataResult>,
-    pub(crate) fetch_build_data_queue: OpQueue<BuildDataCollector, ()>,
+    pub(crate) fetch_build_data_queue:
+        OpQueue<BuildDataCollector, Option<anyhow::Result<BuildDataResult>>>,
 
     latest_requests: Arc<RwLock<LatestRequests>>,
 }
@@ -140,10 +145,12 @@ impl GlobalState {
             status: Status::default(),
             source_root_config: SourceRootConfig::default(),
             proc_macro_client: None,
+
             workspaces: Arc::new(Vec::new()),
             fetch_workspaces_queue: OpQueue::default(),
             workspace_build_data: None,
             fetch_build_data_queue: OpQueue::default(),
+
             latest_requests: Default::default(),
         }
     }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index e88f16cc1..eec6676e0 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -12,6 +12,7 @@ use ide::{Canceled, FileId};
 use ide_db::base_db::VfsPath;
 use lsp_server::{Connection, Notification, Request, Response};
 use lsp_types::notification::Notification as _;
+use project_model::BuildDataCollector;
 use vfs::ChangeKind;
 
 use crate::{
@@ -227,8 +228,15 @@ impl GlobalState {
                                     (Progress::Report, Some(msg))
                                 }
                                 ProjectWorkspaceProgress::End(workspaces) => {
-                                    self.fetch_workspaces_completed();
-                                    self.switch_workspaces(workspaces, None);
+                                    self.fetch_workspaces_completed(workspaces);
+                                    self.switch_workspaces();
+                                    if self.config.run_build_scripts() {
+                                        let mut collector = BuildDataCollector::default();
+                                        for ws in self.workspaces.iter() {
+                                            ws.collect_build_data_configs(&mut collector);
+                                        }
+                                        self.fetch_build_data_request(collector)
+                                    }
                                     (Progress::End, None)
                                 }
                             };
@@ -240,11 +248,9 @@ impl GlobalState {
                                 BuildDataProgress::Report(msg) => {
                                     (Some(Progress::Report), Some(msg))
                                 }
-                                BuildDataProgress::End(collector) => {
-                                    self.fetch_build_data_completed();
-                                    let workspaces =
-                                        (*self.workspaces).clone().into_iter().map(Ok).collect();
-                                    self.switch_workspaces(workspaces, Some(collector));
+                                BuildDataProgress::End(build_data_result) => {
+                                    self.fetch_build_data_completed(build_data_result);
+                                    self.switch_workspaces();
                                     (Some(Progress::End), None)
                                 }
                             };
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index d12f891bb..cdd6eae69 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -139,8 +139,11 @@ impl GlobalState {
             sender.send(Task::FetchBuildData(BuildDataProgress::End(res))).unwrap();
         });
     }
-    pub(crate) fn fetch_build_data_completed(&mut self) {
-        self.fetch_build_data_queue.op_completed(())
+    pub(crate) fn fetch_build_data_completed(
+        &mut self,
+        build_data: anyhow::Result<BuildDataResult>,
+    ) {
+        self.fetch_build_data_queue.op_completed(Some(build_data))
     }
 
     pub(crate) fn fetch_workspaces_request(&mut self) {
@@ -194,54 +197,55 @@ impl GlobalState {
             }
         });
     }
-    pub(crate) fn fetch_workspaces_completed(&mut self) {
-        self.fetch_workspaces_queue.op_completed(())
-    }
-
-    pub(crate) fn switch_workspaces(
+    pub(crate) fn fetch_workspaces_completed(
         &mut self,
         workspaces: Vec<anyhow::Result<ProjectWorkspace>>,
-        workspace_build_data: Option<anyhow::Result<BuildDataResult>>,
     ) {
+        self.fetch_workspaces_queue.op_completed(workspaces)
+    }
+
+    pub(crate) fn switch_workspaces(&mut self) {
         let _p = profile::span("GlobalState::switch_workspaces");
+        let workspaces = self.fetch_workspaces_queue.last_op_result();
         log::info!("will switch workspaces: {:?}", workspaces);
 
-        let mut has_errors = false;
+        let mut error_message = None;
         let workspaces = workspaces
-            .into_iter()
-            .filter_map(|res| {
-                res.map_err(|err| {
-                    has_errors = true;
+            .iter()
+            .filter_map(|res| match res {
+                Ok(it) => Some(it.clone()),
+                Err(err) => {
                     log::error!("failed to load workspace: {:#}", err);
-                    if self.workspaces.is_empty() {
-                        self.show_message(
-                            lsp_types::MessageType::Error,
-                            format!("rust-analyzer failed to load workspace: {:#}", err),
-                        );
-                    }
-                })
-                .ok()
+                    let message = error_message.get_or_insert_with(String::new);
+                    stdx::format_to!(
+                        message,
+                        "rust-analyzer failed to load workspace: {:#}\n",
+                        err
+                    );
+                    None
+                }
             })
             .collect::<Vec<_>>();
 
-        let workspace_build_data = match workspace_build_data {
-            Some(Ok(it)) => Some(it),
+        let workspace_build_data = match self.fetch_build_data_queue.last_op_result() {
+            Some(Ok(it)) => Some(it.clone()),
+            None => None,
             Some(Err(err)) => {
                 log::error!("failed to fetch build data: {:#}", err);
-                self.show_message(
-                    lsp_types::MessageType::Error,
-                    format!("rust-analyzer failed to fetch build data: {:#}", err),
-                );
-                return;
+                let message = error_message.get_or_insert_with(String::new);
+                stdx::format_to!(message, "rust-analyzer failed to fetch build data: {:#}\n", err);
+                None
             }
-            None => None,
         };
 
-        if *self.workspaces == workspaces && self.workspace_build_data == workspace_build_data {
-            return;
+        if let Some(error_message) = error_message {
+            self.show_message(lsp_types::MessageType::Error, error_message);
+            if !self.workspaces.is_empty() {
+                return;
+            }
         }
 
-        if !self.workspaces.is_empty() && has_errors {
+        if *self.workspaces == workspaces && self.workspace_build_data == workspace_build_data {
             return;
         }
 
@@ -337,14 +341,6 @@ impl GlobalState {
         };
         change.set_crate_graph(crate_graph);
 
-        if self.config.run_build_scripts() && workspace_build_data.is_none() {
-            let mut collector = BuildDataCollector::default();
-            for ws in &workspaces {
-                ws.collect_build_data_configs(&mut collector);
-            }
-            self.fetch_build_data_request(collector)
-        }
-
         self.source_root_config = project_folders.source_root_config;
         self.workspaces = Arc::new(workspaces);
         self.workspace_build_data = workspace_build_data;