From b006d1552eb3b930605cfa41b5a8c33fe75a4607 Mon Sep 17 00:00:00 2001
From: Vitaly Slobodin <vitaliy.slobodin@gmail.com>
Date: Sat, 9 Nov 2024 13:06:51 +0100
Subject: [PATCH] lsp: make diagnostics results optional

Requesting diagnostics for a document
can return an empty result meaning
there are no new diagnostics for the current document.
Returning an empty vector could indicate
that. It would be good to avoid that
and return `None` if diagnostics
haven't changed.
---
 crates/project/src/lsp_command.rs | 14 +++++++-------
 crates/project/src/lsp_store.rs   | 19 +++++++++++--------
 2 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/crates/project/src/lsp_command.rs b/crates/project/src/lsp_command.rs
index f1f2ca5bd636a..9760ce6530c6d 100644
--- a/crates/project/src/lsp_command.rs
+++ b/crates/project/src/lsp_command.rs
@@ -3044,7 +3044,7 @@ impl LspCommand for LinkedEditingRange {
 
 #[async_trait(?Send)]
 impl LspCommand for GetDocumentDiagnostics {
-    type Response = Vec<Diagnostic>;
+    type Response = Option<Vec<Diagnostic>>;
     type LspRequest = lsp::request::DocumentDiagnosticRequest;
     type ProtoRequest = proto::GetDocumentDiagnostics;
 
@@ -3088,15 +3088,15 @@ impl LspCommand for GetDocumentDiagnostics {
         _: Model<Buffer>,
         _: LanguageServerId,
         _: AsyncAppContext,
-    ) -> Result<Vec<Diagnostic>> {
+    ) -> Result<Self::Response> {
         match message {
             lsp::DocumentDiagnosticReportResult::Report(report) => match report {
                 lsp::DocumentDiagnosticReport::Full(report) => {
-                    Ok(report.full_document_diagnostic_report.items.clone())
+                    Ok(Some(report.full_document_diagnostic_report.items.clone()))
                 }
-                lsp::DocumentDiagnosticReport::Unchanged(_) => Ok(vec![]),
+                lsp::DocumentDiagnosticReport::Unchanged(_) => Ok(None),
             },
-            lsp::DocumentDiagnosticReportResult::Partial(_) => Ok(vec![]),
+            lsp::DocumentDiagnosticReportResult::Partial(_) => Ok(None),
         }
     }
 
@@ -3130,7 +3130,7 @@ impl LspCommand for GetDocumentDiagnostics {
     }
 
     fn response_to_proto(
-        _: Vec<Diagnostic>,
+        _: Self::Response,
         _: &mut LspStore,
         _: PeerId,
         _: &clock::Global,
@@ -3145,7 +3145,7 @@ impl LspCommand for GetDocumentDiagnostics {
         _: Model<LspStore>,
         _: Model<Buffer>,
         _: AsyncAppContext,
-    ) -> Result<Vec<Diagnostic>> {
+    ) -> Result<Self::Response> {
         todo!()
     }
 
diff --git a/crates/project/src/lsp_store.rs b/crates/project/src/lsp_store.rs
index d692b3458a940..e172c59681bd7 100644
--- a/crates/project/src/lsp_store.rs
+++ b/crates/project/src/lsp_store.rs
@@ -809,6 +809,7 @@ impl LspStore {
         client.add_model_request_handler(Self::handle_lsp_command::<PerformRename>);
         client.add_model_request_handler(Self::handle_lsp_command::<lsp_ext_command::ExpandMacro>);
         client.add_model_request_handler(Self::handle_lsp_command::<LinkedEditingRange>);
+        client.add_model_request_handler(Self::handle_lsp_command::<GetDocumentDiagnostics>);
     }
 
     pub fn as_remote(&self) -> Option<&RemoteLspStore> {
@@ -3195,23 +3196,25 @@ impl LspStore {
 
                 Ok(diagnostics
                     .into_iter()
-                    .collect::<Result<Vec<Vec<_>>>>()?
+                    .collect::<Result<Vec<_>>>()?
                     .into_iter()
-                    .flatten()
+                    .flat_map(|diagnostics| diagnostics.into_iter().flatten())
                     .collect())
             })
         } else {
             let all_actions_task = self.request_multiple_lsp_locally(
                 buffer_handle,
                 Some(position),
-                GetDocumentDiagnostics {
-                    position: position.clone(),
-                },
+                GetDocumentDiagnostics { position },
                 cx,
             );
-            cx.spawn(
-                |_, _| async move { Ok(all_actions_task.await.into_iter().flatten().collect()) },
-            )
+            cx.spawn(|_, _| async move {
+                Ok(all_actions_task
+                    .await
+                    .into_iter()
+                    .flat_map(|diagnostics| diagnostics.into_iter().flatten())
+                    .collect())
+            })
         }
     }