Use an enum for backgroundPreparationMode in the configuration file instead of a string

Author: kateinoigakukun

Documentation/Configuration File.md

@@ -47,7 +47,10 @@ The structure of the file is currently not guaranteed to be stable. Options may
 - `defaultWorkspaceType: "buildServer"|"compilationDatabase"|"swiftPM"`: Default workspace type. Overrides workspace type selection logic.
 - `generatedFilesPath: string`: Directory in which generated interfaces and macro expansions should be stored.
 - `backgroundIndexing: boolean`: Whether background indexing is enabled.
-- `backgroundPreparationMode: string`: Determines how background indexing should prepare a target. Possible values are: - `build`: Build a target to prepare it. - `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.
+- `backgroundPreparationMode: "build"|"noLazy"|"enabled"`: Determines how background indexing should prepare a target.
+  - `build`: Build a target to prepare it.
+  - `noLazy`: Prepare a target without generating object files but do not do lazy type checking and function body skipping. This uses SwiftPM's `--experimental-prepare-for-indexing-no-lazy` flag.
+  - `enabled`: Prepare a target without generating object files.
 - `cancelTextDocumentRequestsOnEditAndClose: boolean`: Whether sending a `textDocument/didChange` or `textDocument/didClose` notification for a document should cancel all pending requests for that document.
 - `experimentalFeatures: ("on-type-formatting")[]`: Experimental features that are enabled.
 - `swiftPublishDiagnosticsDebounceDuration: number`: The time that `SwiftLanguageService` should wait after an edit before starting to compute diagnostics and sending a `PublishDiagnosticsNotification`.

Sources/SKOptions/SourceKitLSPOptions.swift

@@ -242,11 +242,11 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
     }
   }
 
-  public enum BackgroundPreparationMode: String {
+  public enum BackgroundPreparationMode: String, Sendable, Codable, Equatable {
     /// Build a target to prepare it.
     case build
 
-    /// Prepare a target without generating object files but do not do lazy type checking.
+    /// Prepare a target without generating object files but do not do lazy type checking and function body skipping.
     ///
     /// This uses SwiftPM's `--experimental-prepare-for-indexing-no-lazy` flag.
     case noLazy
@@ -315,17 +315,11 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
     return backgroundIndexing ?? true
   }
 
-  /// Determines how background indexing should prepare a target. Possible values are:
-  ///   - `build`: Build a target to prepare it.
-  ///   - `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.
-  public var backgroundPreparationMode: String?
+  /// Determines how background indexing should prepare a target.
+  public var backgroundPreparationMode: BackgroundPreparationMode?
 
   public var backgroundPreparationModeOrDefault: BackgroundPreparationMode {
-    if let backgroundPreparationMode, let parsed = BackgroundPreparationMode(rawValue: backgroundPreparationMode) {
-      return parsed
-    }
-    return .enabled
+    return backgroundPreparationMode ?? .enabled
   }
 
   /// Whether sending a `textDocument/didChange` or `textDocument/didClose` notification for a document should cancel
@@ -389,7 +383,7 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
     defaultWorkspaceType: WorkspaceType? = nil,
     generatedFilesPath: String? = nil,
     backgroundIndexing: Bool? = nil,
-    backgroundPreparationMode: String? = nil,
+    backgroundPreparationMode: BackgroundPreparationMode? = nil,
     cancelTextDocumentRequestsOnEditAndClose: Bool? = nil,
     experimentalFeatures: Set<ExperimentalFeature>? = nil,
     swiftPublishDiagnosticsDebounceDuration: Double? = nil,

Tests/SourceKitLSPTests/BackgroundIndexingTests.swift

@@ -1074,7 +1074,7 @@ final class BackgroundIndexingTests: XCTestCase {
   func testCrossModuleFunctionalityEvenIfLowLevelModuleHasErrors() async throws {
     try await SkipUnless.swiftPMSupportsExperimentalPrepareForIndexing()
     var options = SourceKitLSPOptions.testDefault()
-    options.backgroundPreparationMode = SourceKitLSPOptions.BackgroundPreparationMode.enabled.rawValue
+    options.backgroundPreparationMode = .enabled
     let project = try await SwiftPMTestProject(
       files: [
         "LibA/LibA.swift": """
@@ -1121,7 +1121,7 @@ final class BackgroundIndexingTests: XCTestCase {
   func testCrossModuleFunctionalityWithPreparationNoSkipping() async throws {
     try await SkipUnless.swiftPMSupportsExperimentalPrepareForIndexing()
     var options = SourceKitLSPOptions.testDefault()
-    options.backgroundPreparationMode = SourceKitLSPOptions.BackgroundPreparationMode.noLazy.rawValue
+    options.backgroundPreparationMode = .noLazy
     let project = try await SwiftPMTestProject(
       files: [
         "LibA/LibA.swift": """
@@ -1406,7 +1406,7 @@ final class BackgroundIndexingTests: XCTestCase {
     try SkipUnless.longTestsEnabled()
 
     var options = SourceKitLSPOptions.testDefault()
-    options.backgroundPreparationMode = SourceKitLSPOptions.BackgroundPreparationMode.enabled.rawValue
+    options.backgroundPreparationMode = .enabled
     options.indexOrDefault.updateIndexStoreTimeout = 1 /* second */
 
     let dateStarted = Date()
@@ -1538,7 +1538,7 @@ final class BackgroundIndexingTests: XCTestCase {
         )
         """,
       options: SourceKitLSPOptions(
-        backgroundPreparationMode: SourceKitLSPOptions.BackgroundPreparationMode.enabled.rawValue
+        backgroundPreparationMode: .enabled
       ),
       enableBackgroundIndexing: true
     )
@@ -1602,7 +1602,7 @@ final class BackgroundIndexingTests: XCTestCase {
         )
         """,
       options: SourceKitLSPOptions(
-        backgroundPreparationMode: SourceKitLSPOptions.BackgroundPreparationMode.enabled.rawValue
+        backgroundPreparationMode: .enabled
       ),
       enableBackgroundIndexing: true
     )

Utilities/ConfigSchemaGen/Sources/ConfigSchemaGen/OptionDocument.swift

@@ -48,10 +48,22 @@ struct OptionDocumentBuilder {
         doc += " " + description.split(separator: "\n").joined(separator: "\n\(indent)  ")
       }
       doc += "\n"
-      if case .object(let schema) = type.kind {
+      switch type.kind {
+      case .object(let schema):
         for property in schema.properties {
           try appendProperty(property, indentLevel: indentLevel + 1)
         }
+      case .enum(let schema):
+        for caseInfo in schema.cases {
+          // Add detailed description for each case if available
+          guard let description = caseInfo.description else {
+            continue
+          }
+          doc += "\(indent)  - `\(caseInfo.name)`"
+          doc += ": " + description.split(separator: "\n").joined(separator: "\n\(indent)    ")
+          doc += "\n"
+        }
+      default: break
       }
     }
     guard case .object(let schema) = schema.kind else {

config.schema.json

@@ -8,8 +8,18 @@
       "type" : "boolean"
     },
     "backgroundPreparationMode" : {
-      "description" : "Determines how background indexing should prepare a target. Possible values are: - `build`: Build a target to prepare it. - `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.",
-      "markdownDescription" : "Determines how background indexing should prepare a target. Possible values are: - `build`: Build a target to prepare it. - `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.",
+      "description" : "Determines how background indexing should prepare a target.",
+      "enum" : [
+        "build",
+        "noLazy",
+        "enabled"
+      ],
+      "markdownDescription" : "Determines how background indexing should prepare a target.",
+      "markdownEnumDescriptions" : {
+        "build" : "Build a target to prepare it.",
+        "enabled" : "Prepare a target without generating object files.",
+        "noLazy" : "Prepare a target without generating object files but do not do lazy type checking and function body skipping. This uses SwiftPM's `--experimental-prepare-for-indexing-no-lazy` flag."
+      },
       "type" : "string"
     },
     "buildSettingsTimeout" : {