Hide on-type-formatting behind an experimental feature flag

Author: MahdiBM

Documentation/Configuration File.md

@@ -51,5 +51,5 @@ The structure of the file is currently not guaranteed to be stable. Options may
   - `noLazy`: Prepare a target without generating object files but do not do lazy type checking and function body skipping
   - `enabled`: Prepare a target without generating object files and the like
 - `cancelTextDocumentRequestsOnEditAndClose: bool`: Whether sending a `textDocument/didChange` or `textDocument/didClose` notification for a document should cancel all pending requests for that document.
-- `experimentalFeatures: string[]`: Experimental features to enable
+- `experimentalFeatures: string[]`: Experimental features to enable. Available options: on-type-formatting
 - `swiftPublishDiagnosticsDebounceDuration: double`: The time that `SwiftLanguageService` should wait after an edit before starting to compute diagnostics and sending a `PublishDiagnosticsNotification`.

Sources/SKOptions/ExperimentalFeatures.swift

@@ -10,9 +10,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-/// An experimental feature that can be enabled by passing `--experimental-feature` to `sourcekit-lsp` on the command
-/// line. The raw value of this feature is how it is named on the command line.
+/// An experimental feature that can be enabled by passing `--experimental-feature`
+/// to `sourcekit-lsp` on the command line or through the configuration file.
+/// The raw value of this feature is how it is named on the command line.
 public enum ExperimentalFeature: String, Codable, Sendable, CaseIterable {
-  /* This is here to silence the errors when the enum doesn't have any cases */
-  case exampleCase = "example-case"
+  case onTypeFormatting = "on-type-formatting"
 }

Sources/SourceKitLSP/SourceKitLSPServer.swift

@@ -975,7 +975,8 @@ extension SourceKitLSPServer {
     let result = InitializeResult(
       capabilities: await self.serverCapabilities(
         for: req.capabilities,
-        registry: self.capabilityRegistry!
+        registry: self.capabilityRegistry!,
+        options: options
       )
     )
     logger.logFullObjectInMultipleLogMessages(header: "Initialize response", AnyRequestType(request: req))
@@ -984,7 +985,8 @@ extension SourceKitLSPServer {
 
   func serverCapabilities(
     for client: ClientCapabilities,
-    registry: CapabilityRegistry
+    registry: CapabilityRegistry,
+    options: SourceKitLSPOptions
   ) async -> ServerCapabilities {
     let completionOptions =
       await registry.clientHasDynamicCompletionRegistration
@@ -994,6 +996,11 @@ extension SourceKitLSPServer {
         triggerCharacters: [".", "("]
       )
 
+    let onTypeFormattingOptions =
+      options.hasExperimentalFeature(.onTypeFormatting)
+      ? DocumentOnTypeFormattingOptions(triggerCharacters: ["\n", "\r\n", "\r", "{", "}", ";", ".", ":", "#"])
+      : nil
+
     let foldingRangeOptions =
       await registry.clientHasDynamicFoldingRangeRegistration
       ? nil
@@ -1043,9 +1050,7 @@ extension SourceKitLSPServer {
       codeLensProvider: CodeLensOptions(),
       documentFormattingProvider: .value(DocumentFormattingOptions(workDoneProgress: false)),
       documentRangeFormattingProvider: .value(DocumentRangeFormattingOptions(workDoneProgress: false)),
-      documentOnTypeFormattingProvider: DocumentOnTypeFormattingOptions(triggerCharacters: [
-        "\n", "\r\n", "\r", "{", "}", ";", ".", ":", "#",
-      ]),
+      documentOnTypeFormattingProvider: onTypeFormattingOptions,
       renameProvider: .value(RenameOptions(prepareProvider: true)),
       colorProvider: .bool(true),
       foldingRangeProvider: foldingRangeOptions,