Migrate defaultLanguage(for:) to BSP

Author: ahoppen

Sources/BuildServerProtocol/BuildTargetSourcesRequest.swift

@@ -97,5 +97,30 @@ public struct SourceItemDataKind: RawRepresentable, Codable, Hashable, Sendable
   }
 
   /// `data` field must contain a JvmSourceItemData object.
-  public static let jvm = "jvm"
+  public static let jvm = SourceItemDataKind(rawValue: "jvm")
+
+  /// `data` field must contain a `SourceKitSourceItemData` object.
+  public static let sourceKit = SourceItemDataKind(rawValue: "sourceKit")
+}
+
+public struct SourceKitSourceItemData: LSPAnyCodable, Codable {
+  public var language: Language?
+
+  public init(language: Language? = nil) {
+    self.language = language
+  }
+
+  public init?(fromLSPDictionary dictionary: [String: LanguageServerProtocol.LSPAny]) {
+    if case .string(let language) = dictionary[CodingKeys.language.stringValue] {
+      self.language = Language(rawValue: language)
+    }
+  }
+
+  public func encodeToLSPAny() -> LanguageServerProtocol.LSPAny {
+    var result: [String: LSPAny] = [:]
+    if let language {
+      result[CodingKeys.language.stringValue] = .string(language.rawValue)
+    }
+    return .dictionary(result)
+  }
 }

Sources/BuildSystemIntegration/BuildServerBuildSystem.swift

@@ -338,10 +338,6 @@ extension BuildServerBuildSystem: BuiltInBuildSystem {
     )
   }
 
-  package func defaultLanguage(for document: DocumentURI) async -> Language? {
-    return nil
-  }
-
   package func toolchain(for uri: DocumentURI, _ language: Language) async -> Toolchain? {
     return nil
   }

Sources/BuildSystemIntegration/BuildSystemManager.swift

@@ -191,11 +191,38 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
     self.mainFilesProvider = mainFilesProvider
   }
 
+  /// Ask the build system if it explicitly specifies a language for this document. Return `nil` if it does not.
+  private func languageInferredFromBuildSystem(
+    for document: DocumentURI,
+    in target: BuildTargetIdentifier
+  ) async throws -> Language? {
+    let sourcesItems = try await self.sourceFiles(in: [target])
+    let sourceFiles = sourcesItems.flatMap(\.sources)
+    var result: Language? = nil
+    for sourceFile in sourceFiles {
+      guard sourceFile.uri == document, sourceFile.dataKind == .sourceKit, case .dictionary(let data) = sourceFile.data,
+        let sourceKitData = SourceKitSourceItemData(fromLSPDictionary: data),
+        let language = sourceKitData.language
+      else {
+        continue
+      }
+      if result != nil && result != language {
+        logger.error("Conflicting languages for \(document.forLogging) in \(target)")
+        return nil
+      }
+      result = language
+    }
+    return result
+  }
+
   /// Returns the language that a document should be interpreted in for background tasks where the editor doesn't
   /// specify the document's language.
-  package func defaultLanguage(for document: DocumentURI) async -> Language? {
-    if let defaultLanguage = await buildSystem?.underlyingBuildSystem.defaultLanguage(for: document) {
-      return defaultLanguage
+  package func defaultLanguage(for document: DocumentURI, in target: BuildTargetIdentifier) async -> Language? {
+    let language = await orLog("Getting source files to determine default language") {
+      try await languageInferredFromBuildSystem(for: document, in: target)
+    }
+    if let language {
+      return language
     }
     switch document.fileURL?.pathExtension {
     case "c": return .c
@@ -237,7 +264,7 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
 
   /// Returns the target's module name as parsed from the `BuildTargetIdentifier`'s compiler arguments.
   package func moduleName(for document: DocumentURI, in target: BuildTargetIdentifier) async -> String? {
-    guard let language = await self.defaultLanguage(for: document),
+    guard let language = await self.defaultLanguage(for: document, in: target),
       let buildSettings = await buildSettings(for: document, in: target, language: language)
     else {
       return nil
@@ -406,6 +433,8 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
       return []
     }
 
+    // FIXME: (BSP migration) If we have a cached request for a superset of the targets, serve the result from that
+    // cache entry.
     let request = BuildTargetSourcesRequest.init(targets: targets)
     let response = try await cachedTargetSources.get(request) { request in
       try await buildSystem.send(request)
@@ -416,6 +445,7 @@ package actor BuildSystemManager: BuiltInBuildSystemAdapterDelegate {
   package func sourceFiles() async throws -> [SourceFileInfo] {
     // FIXME: (BSP Migration): Consider removing this method and letting callers get all targets first and then
     // retrieving the source files for those targets.
+    // FIXME: (BSP Migration) Handle source files that are in multiple targets
     let targets = try await self.buildTargets()
     let targetsById = Dictionary(elements: targets, keyedBy: \.id)
     let sourceFiles = try await self.sourceFiles(in: targets.map(\.id)).flatMap { sourcesItem in

Sources/BuildSystemIntegration/BuiltInBuildSystem.swift

@@ -139,13 +139,6 @@ package protocol BuiltInBuildSystem: AnyObject, Sendable {
   /// Returning `nil` indicates that all targets should be considered depending on the given target.
   func targets(dependingOn targets: [BuildTargetIdentifier]) async -> [BuildTargetIdentifier]?
 
-  /// If the build system has knowledge about the language that this document should be compiled in, return it.
-  ///
-  /// This is used to determine the language in which a source file should be background indexed.
-  ///
-  /// If `nil` is returned, the language based on the file's extension.
-  func defaultLanguage(for document: DocumentURI) async -> Language?
-
   /// The toolchain that should be used to open the given document.
   ///
   /// If `nil` is returned, then the default toolchain for the given language is used.

Sources/BuildSystemIntegration/CompilationDatabaseBuildSystem.swift

@@ -160,10 +160,6 @@ extension CompilationDatabaseBuildSystem: BuiltInBuildSystem {
     )
   }
 
-  package func defaultLanguage(for document: DocumentURI) async -> Language? {
-    return nil
-  }
-
   package func toolchain(for uri: DocumentURI, _ language: Language) async -> Toolchain? {
     return nil
   }

Sources/BuildSystemIntegration/SwiftPMBuildSystem.swift

@@ -563,6 +563,8 @@ extension SwiftPMBuildSystem: BuildSystemIntegration.BuiltInBuildSystem {
 
   package func buildTargetSources(request: BuildTargetSourcesRequest) async throws -> BuildTargetSourcesResponse {
     var result: [SourcesItem] = []
+    // TODO: Query The SwiftPM build system for the document's language and add it to SourceItem.data
+    // (https://github.com/swiftlang/sourcekit-lsp/issues/1267)
     for target in request.targets {
       guard let swiftPMTarget = self.targets[target] else {
         continue
@@ -617,11 +619,6 @@ extension SwiftPMBuildSystem: BuildSystemIntegration.BuiltInBuildSystem {
     )
   }
 
-  package func defaultLanguage(for document: DocumentURI) -> Language? {
-    // TODO: Query The SwiftPM build system for the document's language. (https://github.com/swiftlang/sourcekit-lsp/issues/1267)
-    return nil
-  }
-
   package func toolchain(for uri: DocumentURI, _ language: Language) async -> Toolchain? {
     return toolchain
   }

Sources/BuildSystemIntegration/TestBuildSystem.swift

@@ -76,10 +76,6 @@ package actor TestBuildSystem: BuiltInBuildSystem {
     return buildSettingsByFile[request.textDocument.uri]
   }
 
-  package func defaultLanguage(for document: DocumentURI) async -> Language? {
-    return nil
-  }
-
   package func toolchain(for uri: DocumentURI, _ language: Language) async -> Toolchain? {
     return nil
   }

Sources/SemanticIndex/SemanticIndexManager.swift

@@ -590,11 +590,6 @@ package final actor SemanticIndexManager {
       if await indexStoreUpToDateTracker.isUpToDate($0.sourceFile) {
         return false
       }
-      guard let language = await buildSystemManager.defaultLanguage(for: $0.mainFile),
-        UpdateIndexStoreTaskDescription.canIndex(language: language)
-      else {
-        return false
-      }
       return true
     }
     // sort files to get deterministic indexing order
@@ -611,6 +606,12 @@ package final actor SemanticIndexManager {
         )
         continue
       }
+      guard let language = await buildSystemManager.defaultLanguage(for: fileToIndex.mainFile, in: target),
+        UpdateIndexStoreTaskDescription.canIndex(language: language)
+      else {
+        continue
+      }
+
       filesByTarget[target, default: []].append(fileToIndex)
     }
 

Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift

@@ -235,7 +235,7 @@ package struct UpdateIndexStoreTaskDescription: IndexTaskDescription {
     if file.mainFile != file.sourceFile {
       logger.log("Updating index store of \(file.forLogging) using main file \(file.mainFile.forLogging)")
     }
-    guard let language = await buildSystemManager.defaultLanguage(for: file.mainFile) else {
+    guard let language = await buildSystemManager.defaultLanguage(for: file.mainFile, in: target) else {
       logger.error("Not indexing \(file.forLogging) because its language could not be determined")
       return
     }