3 files changed, 26 insertions, 4 deletions

diff --git a/crates/ra_lsp_server/src/caps.rs b/crates/ra_lsp_server/src/caps.rs
index 8d508a3ba..a74f9f27b 100644
--- a/crates/ra_lsp_server/src/caps.rs
+++ b/crates/ra_lsp_server/src/caps.rs
@@ -28,7 +28,7 @@ pub fn server_capabilities() -> ServerCapabilities {
         type_definition_provider: None,
         implementation_provider: None,
         references_provider: Some(true),
-        document_highlight_provider: None,
+        document_highlight_provider: Some(true),
         document_symbol_provider: Some(true),
         workspace_symbol_provider: Some(true),
         code_action_provider: Some(CodeActionProviderCapability::Simple(true)),
diff --git a/crates/ra_lsp_server/src/main_loop.rs b/crates/ra_lsp_server/src/main_loop.rs
index 3ebae4ecd..46b48830d 100644
--- a/crates/ra_lsp_server/src/main_loop.rs
+++ b/crates/ra_lsp_server/src/main_loop.rs
@@ -300,6 +300,7 @@ fn on_request(
         .on::<req::Rename>(handlers::handle_rename)?
         .on::<req::References>(handlers::handle_references)?
         .on::<req::Formatting>(handlers::handle_formatting)?
+        .on::<req::DocumentHighlightRequest>(handlers::handle_document_highlight)?
         .finish();
     match req {
         Ok(id) => {
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index a2c12a4c1..60441e8ea 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -6,9 +6,8 @@ use languageserver_types::{
     DiagnosticSeverity, DocumentSymbol, Documentation, FoldingRange, FoldingRangeKind,
     FoldingRangeParams, Location, MarkupContent, MarkupKind, MarkedString, Position,
     PrepareRenameResponse, RenameParams, SymbolInformation, TextDocumentIdentifier, TextEdit,
-    Range,
-    WorkspaceEdit, ParameterInformation, ParameterLabel, SignatureInformation, Hover, HoverContents,
-    DocumentFormattingParams,
+    Range, WorkspaceEdit, ParameterInformation, ParameterLabel, SignatureInformation, Hover,
+    HoverContents, DocumentFormattingParams, DocumentHighlight,
 };
 use ra_analysis::{FileId, FoldKind, Query, RunnableKind, FileRange, FilePosition, Severity};
 use ra_syntax::{TextUnit, text_utils::intersect};
@@ -673,6 +672,28 @@ pub fn handle_code_action(
     Ok(Some(CodeActionResponse::Commands(res)))
 }
 
+pub fn handle_document_highlight(
+    world: ServerWorld,
+    params: req::TextDocumentPositionParams,
+) -> Result<Option<Vec<DocumentHighlight>>> {
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let line_index = world.analysis().file_line_index(file_id);
+    let offset = params.position.conv_with(&line_index);
+
+    let refs = world
+        .analysis()
+        .find_all_refs(FilePosition { file_id, offset })?;
+
+    Ok(Some(
+        refs.into_iter()
+            .map(|r| DocumentHighlight {
+                range: r.1.conv_with(&line_index),
+                kind: None,
+            })
+            .collect(),
+    ))
+}
+
 pub fn publish_diagnostics(
     world: &ServerWorld,
     file_id: FileId,