Add boilerplate for pull-model diagnostics

Sources/LanguageServerProtocol/SupportTypes/ClientCapabilities.swift

@@ -526,6 +526,16 @@ public struct TextDocumentClientCapabilities: Hashable, Codable {
     }
   }
 
+  /// Capabilities specific to 'textDocument/diagnostic'. Since LSP 3.17.0.
+  public struct Diagnostic: Equatable, Hashable, Codable {
+
+    /// Whether implementation supports dynamic registration.
+    public var dynamicRegistration: Bool?
+
+    /// Whether the clients supports related documents for document diagnostic pulls.
+    public var relatedDocumentSupport: Bool?
+  }
+
   // MARK: Properties
 
   public var synchronization: Synchronization? = nil
@@ -575,6 +585,8 @@ public struct TextDocumentClientCapabilities: Hashable, Codable {
   public var semanticTokens: SemanticTokens? = nil
 
   public var inlayHint: InlayHint? = nil
+
+  public var diagnostic: Diagnostic? = nil
 
   public init(synchronization: Synchronization? = nil,
               completion: Completion? = nil,
@@ -599,7 +611,8 @@ public struct TextDocumentClientCapabilities: Hashable, Codable {
               foldingRange: FoldingRange? = nil,
               callHierarchy: DynamicRegistrationCapability? = nil,
               semanticTokens: SemanticTokens? = nil,
-              inlayHint: InlayHint? = nil) {
+              inlayHint: InlayHint? = nil,
+              diagnostic: Diagnostic? = nil) {
     self.synchronization = synchronization
     self.completion = completion
     self.hover = hover
@@ -624,5 +637,6 @@ public struct TextDocumentClientCapabilities: Hashable, Codable {
     self.callHierarchy = callHierarchy
     self.semanticTokens = semanticTokens
     self.inlayHint = inlayHint
+    self.diagnostic = diagnostic
   }
 }

Sources/LanguageServerProtocol/SupportTypes/RegistrationOptions.swift

@@ -156,6 +156,30 @@ public struct InlayHintRegistrationOptions: RegistrationOptions, TextDocumentReg
   }
 }
 
+/// Describe options to be used when registering for pull diagnostics. Since LSP 3.17.0
+public struct DiagnosticRegistrationOptions: RegistrationOptions, TextDocumentRegistrationOptionsProtocol {
+  public var textDocumentRegistrationOptions: TextDocumentRegistrationOptions
+  public var diagnosticOptions: DiagnosticOptions
+
+  public init(
+    documentSelector: DocumentSelector? = nil,
+    diagnosticOptions: DiagnosticOptions
+  ) {
+    textDocumentRegistrationOptions = TextDocumentRegistrationOptions(documentSelector: documentSelector)
+    self.diagnosticOptions = diagnosticOptions
+  }
+
+  public func encodeIntoLSPAny(dict: inout [String: LSPAny]) {
+    textDocumentRegistrationOptions.encodeIntoLSPAny(dict: &dict)
+
+    dict["interFileDependencies"] = .bool(diagnosticOptions.interFileDependencies)
+    dict["workspaceDiagnostics"] = .bool(diagnosticOptions.workspaceDiagnostics)
+    if let workDoneProgress = diagnosticOptions.workDoneProgress {
+      dict["workDoneProgress"] = .bool(workDoneProgress)
+    }
+  }
+}
+
 /// Describe options to be used when registering for file system change events.
 public struct DidChangeWatchedFilesRegistrationOptions: RegistrationOptions {
   /// The watchers to register.

Sources/LanguageServerProtocol/SupportTypes/ServerCapabilities.swift

@@ -108,6 +108,9 @@ public struct ServerCapabilities: Codable, Hashable {
   /// Whether the server supports the `textDocument/inlayHint` family of requests.
   public var inlayHintProvider: ValueOrBool<InlayHintOptions>?
 
+  /// Whether the server supports the `textDocument/diagnostic` request.
+  public var diagnosticProvider: DiagnosticOptions?
+
   /// Whether the server provides selection range support.
   public var selectionRangeProvider: ValueOrBool<TextDocumentAndStaticRegistrationOptions>?
 
@@ -152,6 +155,7 @@ public struct ServerCapabilities: Codable, Hashable {
     typeHierarchyProvider: ValueOrBool<TextDocumentAndStaticRegistrationOptions>? = nil,
     semanticTokensProvider: SemanticTokensOptions? = nil,
     inlayHintProvider: ValueOrBool<InlayHintOptions>? = nil,
+    diagnosticProvider: DiagnosticOptions? = nil,
     selectionRangeProvider: ValueOrBool<TextDocumentAndStaticRegistrationOptions>? = nil,
     linkedEditingRangeProvider: ValueOrBool<TextDocumentAndStaticRegistrationOptions>? = nil,
     monikerProvider: ValueOrBool<MonikerOptions>? = nil,
@@ -188,6 +192,7 @@ public struct ServerCapabilities: Codable, Hashable {
     self.typeHierarchyProvider = typeHierarchyProvider
     self.semanticTokensProvider = semanticTokensProvider
     self.inlayHintProvider = inlayHintProvider
+    self.diagnosticProvider = diagnosticProvider
     self.selectionRangeProvider = selectionRangeProvider
     self.linkedEditingRangeProvider = linkedEditingRangeProvider
     self.experimental = experimental

Sources/SourceKitLSP/CapabilityRegistry.swift

@@ -31,6 +31,9 @@ public final class CapabilityRegistry {
 
   /// Dynamically registered inlay hint options.
   private var inlayHint: [CapabilityRegistration: InlayHintRegistrationOptions] = [:]
+
+  /// Dynamically registered pull diagnostics options.
+  private var pullDiagnostics: [CapabilityRegistration: DiagnosticRegistrationOptions] = [:]
 
   /// Dynamically registered file watchers.
   private var didChangeWatchedFiles: DidChangeWatchedFilesRegistrationOptions?
@@ -60,6 +63,10 @@ public final class CapabilityRegistry {
     clientCapabilities.textDocument?.inlayHint?.dynamicRegistration == true
   }
 
+  public var clientHasDocumentDiagnosticsRegistration: Bool {
+    clientCapabilities.textDocument?.diagnostic?.dynamicRegistration == true
+  }
+
   public var clientHasDynamicExecuteCommandRegistration: Bool {
     clientCapabilities.workspace?.executeCommand?.dynamicRegistration == true
   }
@@ -202,6 +209,33 @@ public final class CapabilityRegistry {
     registerOnClient(registration)
   }
 
+  /// Dynamically register (pull model) diagnostic capabilities,
+  /// if the client supports it.
+  public func registerDiagnosticIfNeeded(
+    options: DiagnosticOptions,
+    for languages: [Language],
+    registerOnClient: ClientRegistrationHandler
+  ) {
+    guard clientHasDocumentDiagnosticsRegistration else { return }
+    if let registration = registration(for: languages, in: pullDiagnostics) {
+      if options != registration.diagnosticOptions {
+        log("Unable to register new pull diagnostics options \(options) for " +
+            "\(languages) due to pre-existing options \(registration.diagnosticOptions)", level: .warning)
+      }
+      return
+    }
+    let registrationOptions = DiagnosticRegistrationOptions(
+      documentSelector: self.documentSelector(for: languages),
+      diagnosticOptions: options)
+    let registration = CapabilityRegistration(
+      method: DocumentDiagnosticsRequest.method,
+      registerOptions: self.encode(registrationOptions))
+
+    self.pullDiagnostics[registration] = registrationOptions
+
+    registerOnClient(registration)
+  }
+
   /// Dynamically register executeCommand with the given IDs if the client supports
   /// it and we haven't yet registered the given command IDs yet.
   public func registerExecuteCommandIfNeeded(

Sources/SourceKitLSP/Clang/ClangLanguageServer.swift

@@ -515,6 +515,10 @@ extension ClangLanguageServerShim {
     forwardRequestToClangdOnQueue(req)
   }
 
+  func documentDiagnostic(_ req: Request<DocumentDiagnosticsRequest>) {
+    forwardRequestToClangdOnQueue(req)
+  }
+
   func foldingRange(_ req: Request<FoldingRangeRequest>) {
     queue.async {
       if self.capabilities?.foldingRangeProvider?.isSupported == true {

Sources/SourceKitLSP/SourceKitServer.swift

@@ -202,6 +202,8 @@ public final class SourceKitServer: LanguageServer {
     registerToolchainTextDocumentRequest(SourceKitServer.colorPresentation, [])
     registerToolchainTextDocumentRequest(SourceKitServer.codeAction, nil)
     registerToolchainTextDocumentRequest(SourceKitServer.inlayHint, [])
+    registerToolchainTextDocumentRequest(SourceKitServer.documentDiagnostic,
+                                         .full(.init(items: [])))
   }
 
   /// Register a `TextDocumentRequest` that requires a valid `Workspace`, `ToolchainLanguageServer`,
@@ -709,6 +711,11 @@ extension SourceKitServer {
         self.dynamicallyRegisterCapability($0, registry)
       }
     }
+    if let diagnosticOptions = server.diagnosticProvider {
+      registry.registerDiagnosticIfNeeded(options: diagnosticOptions, for: languages) {
+        self.dynamicallyRegisterCapability($0, registry)
+      }
+    }
     if let commandOptions = server.executeCommandProvider {
       registry.registerExecuteCommandIfNeeded(commands: commandOptions.commands) {
         self.dynamicallyRegisterCapability($0, registry)
@@ -1209,6 +1216,14 @@ extension SourceKitServer {
     languageService.inlayHint(req)
   }
 
+  func documentDiagnostic(
+    _ req: Request<DocumentDiagnosticsRequest>,
+    workspace: Workspace,
+    languageService: ToolchainLanguageServer
+  ) {
+    languageService.documentDiagnostic(req)
+  }
+
   /// Converts a location from the symbol index to an LSP location.
   /// 
   /// - Parameter location: The symbol index location

Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift

@@ -1326,6 +1326,11 @@ extension SwiftLanguageServer {
       }
     }
   }
+
+  public func documentDiagnostic(_ req: Request<DocumentDiagnosticsRequest>) {
+    // TODO: Return provider object in initializeSync and implement pull-model document diagnostics here.
+    req.reply(.failure(.unknown("Pull-model diagnostics not implemented yet.")))
+  }
 
   public func executeCommand(_ req: Request<ExecuteCommandRequest>) {
     let params = req.params

Sources/SourceKitLSP/ToolchainLanguageServer.swift

@@ -97,6 +97,7 @@ public protocol ToolchainLanguageServer: AnyObject {
   func colorPresentation(_ req: Request<ColorPresentationRequest>)
   func codeAction(_ req: Request<CodeActionRequest>)
   func inlayHint(_ req: Request<InlayHintRequest>)
+  func documentDiagnostic(_ req: Request<DocumentDiagnosticsRequest>)
 
   // MARK: - Other