Apply various PR suggestions regarding inlay hints

Author: fwcd

Sources/LanguageServerProtocol/Requests/InlayHintsRequest.swift

@@ -26,7 +26,7 @@ public struct InlayHintsRequest: TextDocumentRequest, Hashable {
   /// The document for which to provide the inlay hints.
   public var textDocument: TextDocumentIdentifier
 
-  /// The range the inlay hints are requested for. If unset,
+  /// The range the inlay hints are requested for. If nil,
   /// hints for the entire document are requested.
   @CustomCodable<PositionRange?>
   public var range: Range<Position>?

Sources/SourceKitLSP/Clang/ClangLanguageServer.swift

@@ -491,9 +491,9 @@ extension ClangLanguageServerShim {
   }
 
   func inlayHints(_ req: Request<InlayHintsRequest>) {
-    // Currently a Swift-specific, non-standard request.
-    // Once inlay hints have been upstreamed to LSP, we
-    // can forward them to clangd.
+    // FIXME: Currently a Swift-specific, non-standard request.
+    // Once inlay hints have been upstreamed to LSP, forward
+    // them to clangd.
     req.reply(.success([]))
   }
 

Sources/SourceKitLSP/Swift/ExpressionTypeInfo.swift

@@ -50,7 +50,7 @@ enum ExpressionTypeInfoError: Error, Equatable {
 
 extension SwiftLanguageServer {
   /// Must be called on self.queue.
-  func _expressionTypeInfos(
+  private func _expressionTypeInfos(
     _ uri: DocumentURI,
     _ completion: @escaping (Swift.Result<[ExpressionTypeInfo], ExpressionTypeInfoError>) -> Void
   ) {
@@ -83,6 +83,7 @@ extension SwiftLanguageServer {
       }
 
       var expressionTypeInfos: [ExpressionTypeInfo] = []
+      expressionTypeInfos.reserveCapacity(skExpressionTypeInfos.count)
 
       skExpressionTypeInfos.forEach { (_, skExpressionTypeInfo) -> Bool in
         guard let info = ExpressionTypeInfo(skExpressionTypeInfo, in: snapshot) else {

Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift

@@ -1068,6 +1068,8 @@ extension SwiftLanguageServer {
     let uri = req.params.textDocument.uri
     documentSymbols(uri) { symbolsResult in
       do {
+        /// Filters all the document symbols for which inlay type hints
+        /// should be displayed, i.e. variable bindings, fields and properties.
         func bindings(_ symbols: [DocumentSymbol]) -> [DocumentSymbol] {
           symbols
             .flatMap { bindings($0.children ?? []) + ([.variable, .field, .property].contains($0.kind) ? [$0] : []) }
@@ -1088,10 +1090,11 @@ extension SwiftLanguageServer {
             //
             // Both `"abc" + "def"` and `"def"` are matching expressions. Since we are only
             // interested in the first expression, i.e. the one that corresponds to the
-            // bound expression, we have to do some pre-processing here.
+            // bound expression, we have to do some pre-processing here. Note that this
+            // mechanism currently relies on the outermost expression being reported first.
 
             var visitedPositions: Set<Position> = []
-            var processedInfos: [ExpressionTypeInfo] = [] // end -> start
+            var processedInfos: [ExpressionTypeInfo] = []
 
             // TODO: Compute inlay hints only for the requested range/categories
             // instead of filtering them afterwards.