diff --git a/SourceKitLSPDevUtils/Package.swift b/SourceKitLSPDevUtils/Package.swift
index 83868576f..59456953c 100644
--- a/SourceKitLSPDevUtils/Package.swift
+++ b/SourceKitLSPDevUtils/Package.swift
@@ -1,11 +1,11 @@
-// swift-tools-version: 6.0
+// swift-tools-version: 6.2
 
 import Foundation
 import PackageDescription
 
 let package = Package(
   name: "SourceKitLSPDevUtils",
-  platforms: [.macOS(.v10_15)],
+  platforms: [.macOS(.v14)],
   products: [
     .executable(name: "sourcekit-lsp-dev-utils", targets: ["SourceKitLSPDevUtils"])
   ],
@@ -24,7 +24,8 @@ let package = Package(
         .product(name: "SwiftParser", package: "swift-syntax"),
       ]
     ),
-  ]
+  ],
+  swiftLanguageModes: [.v6]
 )
 
 let dependencies: [(url: String, path: String, fromVersion: Version)] = [
diff --git a/SourceKitLSPDevUtils/Sources/ConfigSchemaGen/ConfigSchemaGen.swift b/SourceKitLSPDevUtils/Sources/ConfigSchemaGen/ConfigSchemaGen.swift
index b08ed2f6b..48c51ef6c 100644
--- a/SourceKitLSPDevUtils/Sources/ConfigSchemaGen/ConfigSchemaGen.swift
+++ b/SourceKitLSPDevUtils/Sources/ConfigSchemaGen/ConfigSchemaGen.swift
@@ -36,15 +36,13 @@ package struct ConfigSchemaGen {
     .deletingLastPathComponent()
   private static let sourceDir =
     projectRoot
-    .appendingPathComponent("Sources")
-    .appendingPathComponent("SKOptions")
+    .appending(components: "Sources", "SKOptions")
   private static let configSchemaJSONPath =
     projectRoot
-    .appendingPathComponent("config.schema.json")
+    .appending(component: "config.schema.json")
   private static let configSchemaDocPath =
     projectRoot
-    .appendingPathComponent("Documentation")
-    .appendingPathComponent("Configuration File.md")
+    .appending(components: "Documentation", "Configuration File.md")
 
   /// Generates and writes the JSON schema and documentation for the SourceKit-LSP configuration file format.
   package static func generate() throws {
diff --git a/Sources/BuildServerIntegration/CompilationDatabase.swift b/Sources/BuildServerIntegration/CompilationDatabase.swift
index 55903a9f9..99bd1314c 100644
--- a/Sources/BuildServerIntegration/CompilationDatabase.swift
+++ b/Sources/BuildServerIntegration/CompilationDatabase.swift
@@ -86,7 +86,7 @@ package struct CompilationDatabaseCompileCommand: Equatable, Codable {
     if filename.isAbsolutePath || !directory.isAbsolutePath {
       return DocumentURI(filePath: filename, isDirectory: false)
     } else {
-      return DocumentURI(URL(fileURLWithPath: directory).appendingPathComponent(filename, isDirectory: false))
+      return DocumentURI(URL(fileURLWithPath: directory).appending(component: filename, directoryHint: .notDirectory))
     }
   }
 }
@@ -127,7 +127,7 @@ package struct JSONCompilationDatabase: Equatable, Codable {
   ///
   /// - Returns: `nil` if `compile_commands.json` was not found
   package init(directory: URL) throws {
-    let path = directory.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+    let path = directory.appending(component: JSONCompilationDatabaseBuildServer.dbName)
     try self.init(file: path)
   }
 
diff --git a/Sources/BuildServerIntegration/DetermineBuildServer.swift b/Sources/BuildServerIntegration/DetermineBuildServer.swift
index 75c7c26a3..725433aea 100644
--- a/Sources/BuildServerIntegration/DetermineBuildServer.swift
+++ b/Sources/BuildServerIntegration/DetermineBuildServer.swift
@@ -40,12 +40,12 @@ private func searchForCompilationDatabaseConfig(
     .compactMap { searchPath in
       let path = workspaceFolder.appending(searchPath)
 
-      let jsonPath = path.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+      let jsonPath = path.appending(component: JSONCompilationDatabaseBuildServer.dbName)
       if FileManager.default.isFile(at: jsonPath) {
         return BuildServerSpec(kind: .jsonCompilationDatabase, projectRoot: workspaceFolder, configPath: jsonPath)
       }
 
-      let fixedPath = path.appendingPathComponent(FixedCompilationDatabaseBuildServer.dbName)
+      let fixedPath = path.appending(component: FixedCompilationDatabaseBuildServer.dbName)
       if FileManager.default.isFile(at: fixedPath) {
         return BuildServerSpec(kind: .fixedCompilationDatabase, projectRoot: workspaceFolder, configPath: fixedPath)
       }
diff --git a/Sources/BuildServerIntegration/ExternalBuildServerAdapter.swift b/Sources/BuildServerIntegration/ExternalBuildServerAdapter.swift
index 481bffa72..3f507f8d8 100644
--- a/Sources/BuildServerIntegration/ExternalBuildServerAdapter.swift
+++ b/Sources/BuildServerIntegration/ExternalBuildServerAdapter.swift
@@ -205,34 +205,34 @@ actor ExternalBuildServerAdapter {
   private static func getConfigPath(for workspaceFolder: URL? = nil, onlyConsiderRoot: Bool = false) -> URL? {
     var buildServerConfigLocations: [URL?] = []
     if let workspaceFolder = workspaceFolder {
-      buildServerConfigLocations.append(workspaceFolder.appendingPathComponent(".bsp"))
+      buildServerConfigLocations.append(workspaceFolder.appending(component: ".bsp"))
     }
 
     if !onlyConsiderRoot {
       #if os(Windows)
       if let localAppData = ProcessInfo.processInfo.environment["LOCALAPPDATA"] {
-        buildServerConfigLocations.append(URL(fileURLWithPath: localAppData).appendingPathComponent("bsp"))
+        buildServerConfigLocations.append(URL(fileURLWithPath: localAppData).appending(component: "bsp"))
       }
       if let programData = ProcessInfo.processInfo.environment["PROGRAMDATA"] {
-        buildServerConfigLocations.append(URL(fileURLWithPath: programData).appendingPathComponent("bsp"))
+        buildServerConfigLocations.append(URL(fileURLWithPath: programData).appending(component: "bsp"))
       }
       #else
       if let xdgDataHome = ProcessInfo.processInfo.environment["XDG_DATA_HOME"] {
-        buildServerConfigLocations.append(URL(fileURLWithPath: xdgDataHome).appendingPathComponent("bsp"))
+        buildServerConfigLocations.append(URL(fileURLWithPath: xdgDataHome).appending(component: "bsp"))
       }
 
       if let libraryUrl = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first {
-        buildServerConfigLocations.append(libraryUrl.appendingPathComponent("bsp"))
+        buildServerConfigLocations.append(libraryUrl.appending(component: "bsp"))
       }
 
       if let xdgDataDirs = ProcessInfo.processInfo.environment["XDG_DATA_DIRS"] {
         buildServerConfigLocations += xdgDataDirs.split(separator: ":").map { xdgDataDir in
-          URL(fileURLWithPath: String(xdgDataDir)).appendingPathComponent("bsp")
+          URL(fileURLWithPath: String(xdgDataDir)).appending(component: "bsp")
         }
       }
 
       if let libraryUrl = FileManager.default.urls(for: .applicationSupportDirectory, in: .systemDomainMask).first {
-        buildServerConfigLocations.append(libraryUrl.appendingPathComponent("bsp"))
+        buildServerConfigLocations.append(libraryUrl.appending(component: "bsp"))
       }
       #endif
     }
@@ -255,7 +255,7 @@ actor ExternalBuildServerAdapter {
 
     // Pre Swift 6.1 SourceKit-LSP looked for `buildServer.json` in the project root. Maintain this search location for
     // compatibility even though it's not a standard BSP search location.
-    if let buildServerPath = workspaceFolder?.appendingPathComponent("buildServer.json"),
+    if let buildServerPath = workspaceFolder?.appending(component: "buildServer.json"),
       FileManager.default.isFile(at: buildServerPath)
     {
       return buildServerPath
diff --git a/Sources/BuildServerIntegration/FixedCompilationDatabaseBuildServer.swift b/Sources/BuildServerIntegration/FixedCompilationDatabaseBuildServer.swift
index ef084482a..672111a1d 100644
--- a/Sources/BuildServerIntegration/FixedCompilationDatabaseBuildServer.swift
+++ b/Sources/BuildServerIntegration/FixedCompilationDatabaseBuildServer.swift
@@ -56,7 +56,7 @@ package actor FixedCompilationDatabaseBuildServer: BuiltInBuildServer {
   }
 
   package var indexDatabasePath: URL? {
-    indexStorePath?.deletingLastPathComponent().appendingPathComponent("IndexDatabase")
+    indexStorePath?.deletingLastPathComponent().appending(component: "IndexDatabase")
   }
 
   package nonisolated var supportsPreparationAndOutputPaths: Bool { false }
diff --git a/Sources/BuildServerIntegration/JSONCompilationDatabaseBuildServer.swift b/Sources/BuildServerIntegration/JSONCompilationDatabaseBuildServer.swift
index abd8e5196..f6e9a619b 100644
--- a/Sources/BuildServerIntegration/JSONCompilationDatabaseBuildServer.swift
+++ b/Sources/BuildServerIntegration/JSONCompilationDatabaseBuildServer.swift
@@ -93,7 +93,7 @@ package actor JSONCompilationDatabaseBuildServer: BuiltInBuildServer {
   }
 
   package var indexDatabasePath: URL? {
-    indexStorePath?.deletingLastPathComponent().appendingPathComponent("IndexDatabase")
+    indexStorePath?.deletingLastPathComponent().appending(component: "IndexDatabase")
   }
 
   package nonisolated var supportsPreparationAndOutputPaths: Bool { false }
diff --git a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
index e357d9b25..fcf5e4d81 100644
--- a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
+++ b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
@@ -144,7 +144,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
   }
 
   static package func searchForConfig(in path: URL, options: SourceKitLSPOptions) -> BuildServerSpec? {
-    let packagePath = path.appendingPathComponent("Package.swift")
+    let packagePath = path.appending(component: "Package.swift")
     if (try? String(contentsOf: packagePath, encoding: .utf8))?.contains("PackageDescription") ?? false {
       return BuildServerSpec(kind: .swiftPM, projectRoot: path, configPath: packagePath)
     }
@@ -494,7 +494,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
   }
 
   package var indexDatabasePath: URL? {
-    return buildPath.appendingPathComponent("index").appendingPathComponent("db")
+    return buildPath.appending(components: "index", "db")
   }
 
   private func indexUnitOutputPath(forSwiftFile uri: DocumentURI) -> String {
@@ -583,7 +583,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
           )
         }
         let packageManifest = SourceItem(
-          uri: DocumentURI(projectRoot.appendingPathComponent("Package.swift")),
+          uri: DocumentURI(projectRoot.appending(component: "Package.swift")),
           kind: .file,
           generated: false
         )
diff --git a/Sources/CompletionScoringTestSupport/RepeatableRandomNumberGenerator.swift b/Sources/CompletionScoringTestSupport/RepeatableRandomNumberGenerator.swift
index 4b37cf7c0..c4c0d8c93 100644
--- a/Sources/CompletionScoringTestSupport/RepeatableRandomNumberGenerator.swift
+++ b/Sources/CompletionScoringTestSupport/RepeatableRandomNumberGenerator.swift
@@ -129,9 +129,7 @@ private let skTestSupportInputsDirectory: URL = {
   #if os(macOS)
   var resources =
     productsDirectory
-    .appendingPathComponent("SourceKitLSP_CompletionScoringTestSupport.bundle")
-    .appendingPathComponent("Contents")
-    .appendingPathComponent("Resources")
+    .appending(components: "SourceKitLSP_CompletionScoringTestSupport.bundle", "Contents", "Resources")
   if !FileManager.default.fileExists(at: resources) {
     // Xcode and command-line swiftpm differ about the path.
     resources.deleteLastPathComponent()
@@ -140,18 +138,18 @@ private let skTestSupportInputsDirectory: URL = {
   #else
   let resources =
     productsDirectory
-    .appendingPathComponent("SourceKitLSP_CompletionScoringTestSupport.resources")
+    .appending(component: "SourceKitLSP_CompletionScoringTestSupport.resources")
   #endif
   guard FileManager.default.fileExists(at: resources) else {
     fatalError("missing resources \(resources)")
   }
-  return resources.appendingPathComponent("INPUTS", isDirectory: true).standardizedFileURL
+  return resources.appending(component: "INPUTS", directoryHint: .isDirectory).standardizedFileURL
 }()
 
 func loadTestResource(name: String, withExtension ext: String) throws -> Data {
   let file =
     skTestSupportInputsDirectory
-    .appendingPathComponent("\(name).\(ext)")
+    .appending(component: "\(name).\(ext)")
   return try Data(contentsOf: file)
 }
 
diff --git a/Sources/Diagnose/DiagnoseCommand.swift b/Sources/Diagnose/DiagnoseCommand.swift
index 76bcc4309..5a251f23d 100644
--- a/Sources/Diagnose/DiagnoseCommand.swift
+++ b/Sources/Diagnose/DiagnoseCommand.swift
@@ -124,7 +124,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
         try await reduce(
           requestInfo: requestInfo,
           toolchain: toolchain,
-          bundlePath: bundlePath.appendingPathComponent("sourcekitd-crash"),
+          bundlePath: bundlePath.appending(component: "sourcekitd-crash"),
           progressUpdate: { (progress, message) in
             reportProgress(
               .reproducingSourcekitdCrash(progress: progress),
@@ -192,7 +192,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
           }
         )
 
-        let bundleDirectory = bundlePath.appendingPathComponent("swift-frontend-crash")
+        let bundleDirectory = bundlePath.appending(component: "swift-frontend-crash")
         try makeReproducerBundle(for: reducedRequesInfo, toolchain: toolchain, bundlePath: bundleDirectory)
 
         // If reduce didn't throw, we have found a reproducer. Stop.
@@ -218,7 +218,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
   private func addOsLog(toBundle bundlePath: URL) async throws {
     #if os(macOS)
     reportProgress(.collectingLogMessages(progress: 0), message: "Collecting log messages")
-    let outputFileUrl = bundlePath.appendingPathComponent("log.txt")
+    let outputFileUrl = bundlePath.appending(component: "log.txt")
     try FileManager.default.createFile(at: outputFileUrl, contents: nil)
     let fileHandle = try FileHandle(forWritingTo: outputFileUrl)
     let bytesCollected = AtomicInt32(initialValue: 0)
@@ -265,12 +265,11 @@ package struct DiagnoseCommand: AsyncParsableCommand {
   private func addNonDarwinLogs(toBundle bundlePath: URL) async throws {
     reportProgress(.collectingLogMessages(progress: 0), message: "Collecting log files")
 
-    let destinationDir = bundlePath.appendingPathComponent("logs")
+    let destinationDir = bundlePath.appending(component: "logs")
     try FileManager.default.createDirectory(at: destinationDir, withIntermediateDirectories: true)
 
     let logFileDirectoryURL = FileManager.default.homeDirectoryForCurrentUser
-      .appendingPathComponent(".sourcekit-lsp")
-      .appendingPathComponent("logs")
+      .appending(components: ".sourcekit-lsp", "logs")
     let enumerator = FileManager.default.enumerator(at: logFileDirectoryURL, includingPropertiesForKeys: nil)
     while let fileUrl = enumerator?.nextObject() as? URL {
       guard fileUrl.lastPathComponent.hasPrefix("sourcekit-lsp") else {
@@ -278,7 +277,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
       }
       try? FileManager.default.copyItem(
         at: fileUrl,
-        to: destinationDir.appendingPathComponent(fileUrl.lastPathComponent)
+        to: destinationDir.appending(component: fileUrl.lastPathComponent)
       )
     }
   }
@@ -294,7 +293,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
     #if os(macOS)
     reportProgress(.collectingCrashReports, message: "Collecting crash reports")
 
-    let destinationDir = bundlePath.appendingPathComponent("crashes")
+    let destinationDir = bundlePath.appending(component: "crashes")
     try FileManager.default.createDirectory(at: destinationDir, withIntermediateDirectories: true)
 
     let processesToIncludeCrashReportsOf = ["SourceKitService", "sourcekit-lsp", "swift-frontend"]
@@ -308,7 +307,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
         }
         try? FileManager.default.copyItem(
           at: fileUrl,
-          to: destinationDir.appendingPathComponent(fileUrl.lastPathComponent)
+          to: destinationDir.appending(component: fileUrl.lastPathComponent)
         )
       }
     }
@@ -317,7 +316,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
 
   @MainActor
   private func addSwiftVersion(toBundle bundlePath: URL) async throws {
-    let outputFileUrl = bundlePath.appendingPathComponent("swift-versions.txt")
+    let outputFileUrl = bundlePath.appending(component: "swift-versions.txt")
     try FileManager.default.createFile(at: outputFileUrl, contents: nil)
     let fileHandle = try FileHandle(forWritingTo: outputFileUrl)
 
@@ -388,8 +387,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
         URL(fileURLWithPath: bundleOutputPath)
       } else {
         FileManager.default.temporaryDirectory
-          .appendingPathComponent("sourcekit-lsp-diagnose")
-          .appendingPathComponent("sourcekit-lsp-diagnose-\(date)")
+          .appending(components: "sourcekit-lsp-diagnose", "sourcekit-lsp-diagnose-\(date)")
       }
     try FileManager.default.createDirectory(at: bundlePath, withIntermediateDirectories: true)
 
diff --git a/Sources/Diagnose/ReduceCommand.swift b/Sources/Diagnose/ReduceCommand.swift
index 80ce597cc..0f1c14ab2 100644
--- a/Sources/Diagnose/ReduceCommand.swift
+++ b/Sources/Diagnose/ReduceCommand.swift
@@ -98,7 +98,7 @@ package struct ReduceCommand: AsyncParsableCommand {
 
     progressBar.complete(success: true)
 
-    let reducedSourceFile = FileManager.default.temporaryDirectory.appendingPathComponent("reduced.swift")
+    let reducedSourceFile = FileManager.default.temporaryDirectory.appending(component: "reduced.swift")
     try reduceRequestInfo.fileContents.write(to: reducedSourceFile, atomically: true, encoding: .utf8)
 
     print("Reduced Request:")
diff --git a/Sources/Diagnose/ReproducerBundle.swift b/Sources/Diagnose/ReproducerBundle.swift
index 8fdccb917..9b2e3d10f 100644
--- a/Sources/Diagnose/ReproducerBundle.swift
+++ b/Sources/Diagnose/ReproducerBundle.swift
@@ -24,13 +24,13 @@ import struct TSCBasic.AbsolutePath
 func makeReproducerBundle(for requestInfo: RequestInfo, toolchain: Toolchain, bundlePath: URL) throws {
   try FileManager.default.createDirectory(at: bundlePath, withIntermediateDirectories: true)
   try requestInfo.fileContents.write(
-    to: bundlePath.appendingPathComponent("input.swift"),
+    to: bundlePath.appending(component: "input.swift"),
     atomically: true,
     encoding: .utf8
   )
   try toolchain.path.realpath.filePath
     .write(
-      to: bundlePath.appendingPathComponent("toolchain.txt"),
+      to: bundlePath.appending(component: "toolchain.txt"),
       atomically: true,
       encoding: .utf8
     )
@@ -38,12 +38,12 @@ func makeReproducerBundle(for requestInfo: RequestInfo, toolchain: Toolchain, bu
     let command =
       "swift-frontend \\\n"
       + requestInfo.compilerArgs.replacing(["$FILE"], with: ["./input.swift"]).joined(separator: " \\\n")
-    try command.write(to: bundlePath.appendingPathComponent("command.sh"), atomically: true, encoding: .utf8)
+    try command.write(to: bundlePath.appending(component: "command.sh"), atomically: true, encoding: .utf8)
   } else {
-    let requests = try requestInfo.requests(for: bundlePath.appendingPathComponent("input.swift"))
+    let requests = try requestInfo.requests(for: bundlePath.appending(component: "input.swift"))
     for (index, request) in requests.enumerated() {
       try request.write(
-        to: bundlePath.appendingPathComponent("request-\(index).yml"),
+        to: bundlePath.appending(component: "request-\(index).yml"),
         atomically: true,
         encoding: .utf8
       )
diff --git a/Sources/Diagnose/SourceKitDRequestExecutor.swift b/Sources/Diagnose/SourceKitDRequestExecutor.swift
index da5cafddb..a63380a2c 100644
--- a/Sources/Diagnose/SourceKitDRequestExecutor.swift
+++ b/Sources/Diagnose/SourceKitDRequestExecutor.swift
@@ -74,7 +74,7 @@ package class OutOfProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
 
   /// The file to which we write the reduce source file.
   private var temporarySourceFile: URL {
-    temporaryDirectory.appendingPathComponent("reduce.swift")
+    temporaryDirectory.appending(component: "reduce.swift")
   }
 
   /// If this predicate evaluates to true on the sourcekitd response, the request is
@@ -86,7 +86,7 @@ package class OutOfProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
     self.pluginPaths = pluginPaths
     self.swiftFrontend = swiftFrontend
     self.reproducerPredicate = reproducerPredicate
-    temporaryDirectory = FileManager.default.temporaryDirectory.appendingPathComponent("sourcekitd-execute-\(UUID())")
+    temporaryDirectory = FileManager.default.temporaryDirectory.appending(component: "sourcekitd-execute-\(UUID())")
     try? FileManager.default.createDirectory(at: temporaryDirectory, withIntermediateDirectories: true)
   }
 
@@ -171,7 +171,7 @@ package class OutOfProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
     try request.fileContents.write(to: temporarySourceFile, atomically: true, encoding: .utf8)
     let requestStrings = try request.requests(for: temporarySourceFile)
     for (index, requestString) in requestStrings.enumerated() {
-      let temporaryRequestFile = temporaryDirectory.appendingPathComponent("request-\(index).yml")
+      let temporaryRequestFile = temporaryDirectory.appending(component: "request-\(index).yml")
       try requestString.write(
         to: temporaryRequestFile,
         atomically: true,
diff --git a/Sources/Diagnose/Toolchain+SwiftFrontend.swift b/Sources/Diagnose/Toolchain+SwiftFrontend.swift
index f8c091018..bb7e1bb0b 100644
--- a/Sources/Diagnose/Toolchain+SwiftFrontend.swift
+++ b/Sources/Diagnose/Toolchain+SwiftFrontend.swift
@@ -20,6 +20,6 @@ extension Toolchain {
   ///
   /// - Note: Not discovered as part of the toolchain because `swift-frontend` is only needed in the diagnose commands.
   package var swiftFrontend: URL? {
-    return swift?.deletingLastPathComponent().appendingPathComponent("swift-frontend")
+    return swift?.deletingLastPathComponent().appending(component: "swift-frontend")
   }
 }
diff --git a/Sources/SKLogging/SetGlobalLogFileHandler.swift b/Sources/SKLogging/SetGlobalLogFileHandler.swift
index dbb92d162..2b2ea8a87 100644
--- a/Sources/SKLogging/SetGlobalLogFileHandler.swift
+++ b/Sources/SKLogging/SetGlobalLogFileHandler.swift
@@ -44,8 +44,9 @@ func getOrCreateLogFileHandle(logDirectory: URL, logRotateCount: Int) -> FileHan
   }
 
   // Name must match the regex in `cleanOldLogFiles` and the prefix in `DiagnoseCommand.addNonDarwinLogs`.
-  let logFileUrl = logDirectory.appendingPathComponent(
-    "sourcekit-lsp-\(ProcessInfo.processInfo.processIdentifier).\(logRotateIndex % logRotateCount).log"
+  let logFileUrl = logDirectory.appending(
+    component:
+      "sourcekit-lsp-\(ProcessInfo.processInfo.processIdentifier).\(logRotateIndex % logRotateCount).log"
   )
 
   do {
diff --git a/Sources/SKOptions/SourceKitLSPOptions.swift b/Sources/SKOptions/SourceKitLSPOptions.swift
index ae4d60857..4a7897118 100644
--- a/Sources/SKOptions/SourceKitLSPOptions.swift
+++ b/Sources/SKOptions/SourceKitLSPOptions.swift
@@ -564,8 +564,7 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
       base: base,
       override: SourceKitLSPOptions(
         path: workspaceFolder.fileURL?
-          .appendingPathComponent(".sourcekit-lsp")
-          .appendingPathComponent("config.json")
+          .appending(components: ".sourcekit-lsp", "config.json")
       )
     )
   }
@@ -575,7 +574,7 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
       return URL(fileURLWithPath: generatedFilesPath)
     }
 
-    return URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("sourcekit-lsp")
+    return URL(fileURLWithPath: NSTemporaryDirectory()).appending(component: "sourcekit-lsp")
   }
 
   public func hasExperimentalFeature(_ feature: ExperimentalFeature) -> Bool {
diff --git a/Sources/SKTestSupport/CustomBuildServerTestProject.swift b/Sources/SKTestSupport/CustomBuildServerTestProject.swift
index 2a5bcc22e..0ecddcd04 100644
--- a/Sources/SKTestSupport/CustomBuildServerTestProject.swift
+++ b/Sources/SKTestSupport/CustomBuildServerTestProject.swift
@@ -179,8 +179,8 @@ package extension CustomBuildServer {
   ) throws -> InitializeBuildResponse {
     return initializationResponse(
       initializeData: SourceKitInitializeBuildResponseData(
-        indexDatabasePath: try projectRoot.appendingPathComponent("index-db").filePath,
-        indexStorePath: try projectRoot.appendingPathComponent("index-store").filePath,
+        indexDatabasePath: try projectRoot.appending(component: "index-db").filePath,
+        indexStorePath: try projectRoot.appending(component: "index-store").filePath,
         outputPathsProvider: outputPathsProvider,
         prepareProvider: true,
         sourceKitOptionsProvider: true
diff --git a/Sources/SKTestSupport/ExternalBuildServerTestProject.swift b/Sources/SKTestSupport/ExternalBuildServerTestProject.swift
index ae0dd35fb..0fa35c02e 100644
--- a/Sources/SKTestSupport/ExternalBuildServerTestProject.swift
+++ b/Sources/SKTestSupport/ExternalBuildServerTestProject.swift
@@ -29,9 +29,7 @@ private let skTestSupportInputsDirectory: URL = {
   #if os(macOS)
   var resources =
     productsDirectory
-    .appendingPathComponent("SourceKitLSP_SKTestSupport.bundle")
-    .appendingPathComponent("Contents")
-    .appendingPathComponent("Resources")
+    .appending(components: "SourceKitLSP_SKTestSupport.bundle", "Contents", "Resources")
   if !FileManager.default.fileExists(at: resources) {
     // Xcode and command-line swiftpm differ about the path.
     resources.deleteLastPathComponent()
@@ -40,12 +38,12 @@ private let skTestSupportInputsDirectory: URL = {
   #else
   let resources =
     productsDirectory
-    .appendingPathComponent("SourceKitLSP_SKTestSupport.resources")
+    .appending(component: "SourceKitLSP_SKTestSupport.resources")
   #endif
   guard FileManager.default.fileExists(at: resources) else {
     fatalError("missing resources \(resources)")
   }
-  return resources.appendingPathComponent("INPUTS", isDirectory: true).standardizedFileURL
+  return resources.appending(component: "INPUTS", directoryHint: .isDirectory).standardizedFileURL
 }()
 
 /// Creates a project that uses a BSP server to provide build settings.
diff --git a/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift b/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
index 9a0ca382d..df3286c98 100644
--- a/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
+++ b/Sources/SKTestSupport/IndexedSingleSwiftFileTestProject.swift
@@ -84,8 +84,8 @@ package struct IndexedSingleSwiftFileTestProject {
   ) async throws {
     let testWorkspaceDirectory = try workspaceDirectory ?? testScratchDir(testName: testName)
 
-    let testFileURL = testWorkspaceDirectory.appendingPathComponent("test.swift")
-    let indexURL = testWorkspaceDirectory.appendingPathComponent("index")
+    let testFileURL = testWorkspaceDirectory.appending(component: "test.swift")
+    let indexURL = testWorkspaceDirectory.appending(component: "index")
     guard let swiftc = await ToolchainRegistry.forTesting.default?.swiftc else {
       throw Error.swiftcNotFound
     }
@@ -115,30 +115,30 @@ package struct IndexedSingleSwiftFileTestProject {
       let sdkUrl = URL(fileURLWithPath: sdk)
       #if os(Windows)
       let platform = sdkUrl.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent()
-      let info = try WindowsPlatformInfo(reading: platform.appendingPathComponent("Info.plist"))
+      let info = try WindowsPlatformInfo(reading: platform.appending(component: "Info.plist"))
       let xctestModuleDir =
         platform
-        .appendingPathComponent("Developer")
-        .appendingPathComponent("Library")
-        .appendingPathComponent("XCTest-\(info.defaults.xctestVersion)")
-        .appendingPathComponent("usr")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("swift")
-        .appendingPathComponent("windows")
+        .appending(
+          components: "Developer",
+          "Library",
+          "XCTest-\(info.defaults.xctestVersion)",
+          "usr",
+          "lib",
+          "swift",
+          "windows"
+        )
       compilerArguments += ["-I", try xctestModuleDir.filePath]
       #else
       let usrLibDir =
         sdkUrl
         .deletingLastPathComponent()
         .deletingLastPathComponent()
-        .appendingPathComponent("usr")
-        .appendingPathComponent("lib")
+        .appending(components: "usr", "lib")
       let frameworksDir =
         sdkUrl
         .deletingLastPathComponent()
         .deletingLastPathComponent()
-        .appendingPathComponent("Library")
-        .appendingPathComponent("Frameworks")
+        .appending(components: "Library", "Frameworks")
       compilerArguments += [
         "-I", try usrLibDir.filePath,
         "-F", try frameworksDir.filePath,
@@ -158,7 +158,7 @@ package struct IndexedSingleSwiftFileTestProject {
     let encoder = JSONEncoder()
     encoder.outputFormatting = [.prettyPrinted, .sortedKeys, .withoutEscapingSlashes]
     try encoder.encode(compilationDatabase).write(
-      to: testWorkspaceDirectory.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+      to: testWorkspaceDirectory.appending(component: JSONCompilationDatabaseBuildServer.dbName)
     )
 
     // Run swiftc to build the index store
diff --git a/Sources/SKTestSupport/MultiFileTestProject.swift b/Sources/SKTestSupport/MultiFileTestProject.swift
index 9e9e61641..0b863a8f5 100644
--- a/Sources/SKTestSupport/MultiFileTestProject.swift
+++ b/Sources/SKTestSupport/MultiFileTestProject.swift
@@ -39,9 +39,9 @@ package struct RelativeFileLocation: Hashable, ExpressibleByStringLiteral {
   package func url(relativeTo: URL) -> URL {
     var url = relativeTo
     for directory in directories {
-      url = url.appendingPathComponent(directory)
+      url = url.appending(component: directory)
     }
-    url = url.appendingPathComponent(fileName)
+    url = url.appending(component: fileName)
     return url
   }
 }
diff --git a/Sources/SKTestSupport/PluginPaths.swift b/Sources/SKTestSupport/PluginPaths.swift
index 7f6d2c695..e7cd8bcca 100644
--- a/Sources/SKTestSupport/PluginPaths.swift
+++ b/Sources/SKTestSupport/PluginPaths.swift
@@ -58,17 +58,13 @@ private func fileExists(at url: URL) -> Bool {
 private func pluginPaths(relativeTo base: URL) -> PluginPaths? {
   // When building in Xcode
   if let buildConfiguration = inferredXcodeBuildConfiguration {
-    let frameworksDir = base.appendingPathComponent("Products")
-      .appendingPathComponent(buildConfiguration)
-      .appendingPathComponent("PackageFrameworks")
+    let frameworksDir = base.appending(components: "Products", buildConfiguration, "PackageFrameworks")
     let clientPlugin =
       frameworksDir
-      .appendingPathComponent("SwiftSourceKitClientPlugin.framework")
-      .appendingPathComponent("SwiftSourceKitClientPlugin")
+      .appending(components: "SwiftSourceKitClientPlugin.framework", "SwiftSourceKitClientPlugin")
     let servicePlugin =
       frameworksDir
-      .appendingPathComponent("SwiftSourceKitPlugin.framework")
-      .appendingPathComponent("SwiftSourceKitPlugin")
+      .appending(components: "SwiftSourceKitPlugin.framework", "SwiftSourceKitPlugin")
     if fileExists(at: clientPlugin) && fileExists(at: servicePlugin) {
       return PluginPaths(clientPlugin: clientPlugin, servicePlugin: servicePlugin)
     }
@@ -76,15 +72,13 @@ private func pluginPaths(relativeTo base: URL) -> PluginPaths? {
 
   // When creating an `xctestproducts` bundle
   do {
-    let frameworksDir = base.appendingPathComponent("PackageFrameworks")
+    let frameworksDir = base.appending(component: "PackageFrameworks")
     let clientPlugin =
       frameworksDir
-      .appendingPathComponent("SwiftSourceKitClientPlugin.framework")
-      .appendingPathComponent("SwiftSourceKitClientPlugin")
+      .appending(components: "SwiftSourceKitClientPlugin.framework", "SwiftSourceKitClientPlugin")
     let servicePlugin =
       frameworksDir
-      .appendingPathComponent("SwiftSourceKitPlugin.framework")
-      .appendingPathComponent("SwiftSourceKitPlugin")
+      .appending(components: "SwiftSourceKitPlugin.framework", "SwiftSourceKitPlugin")
     if fileExists(at: clientPlugin) && fileExists(at: servicePlugin) {
       return PluginPaths(clientPlugin: clientPlugin, servicePlugin: servicePlugin)
     }
@@ -109,8 +103,8 @@ private func pluginPaths(relativeTo base: URL) -> PluginPaths? {
       clientPluginName = "libSwiftSourceKitClientPlugin.so"
       servicePluginName = "libSwiftSourceKitPlugin.so"
     }
-    let clientPlugin = base.appendingPathComponent(clientPluginName)
-    let servicePlugin = base.appendingPathComponent(servicePluginName)
+    let clientPlugin = base.appending(component: clientPluginName)
+    let servicePlugin = base.appending(component: servicePluginName)
     if fileExists(at: clientPlugin) && fileExists(at: servicePlugin) {
       return PluginPaths(clientPlugin: clientPlugin, servicePlugin: servicePlugin)
     }
diff --git a/Sources/SKTestSupport/SkipUnless.swift b/Sources/SKTestSupport/SkipUnless.swift
index 9d8ffdc38..b47dce1c7 100644
--- a/Sources/SKTestSupport/SkipUnless.swift
+++ b/Sources/SKTestSupport/SkipUnless.swift
@@ -217,9 +217,9 @@ package actor SkipUnless {
   ) async throws {
     return try await shared.skipUnlessSupported(allowSkippingInCI: true, file: file, line: line) {
       let swiftFrontend = try await unwrap(ToolchainRegistry.forTesting.default?.swift).deletingLastPathComponent()
-        .appendingPathComponent("swift-frontend")
+        .appending(component: "swift-frontend")
       return try await withTestScratchDir { scratchDirectory in
-        let input = scratchDirectory.appendingPathComponent("Input.swift")
+        let input = scratchDirectory.appending(component: "Input.swift")
         try FileManager.default.createFile(at: input, contents: nil)
         // If we can't compile for wasm, this fails complaining that it can't find the stdlib for wasm.
         let result = try await withTimeout(defaultTimeoutDuration) {
diff --git a/Sources/SKTestSupport/SwiftPMDependencyProject.swift b/Sources/SKTestSupport/SwiftPMDependencyProject.swift
index 79addaee9..cc5d0061b 100644
--- a/Sources/SKTestSupport/SwiftPMDependencyProject.swift
+++ b/Sources/SKTestSupport/SwiftPMDependencyProject.swift
@@ -29,7 +29,7 @@ package class SwiftPMDependencyProject {
 
   /// The directory in which the repository lives.
   package var packageDirectory: URL {
-    return scratchDirectory.appendingPathComponent("MyDependency")
+    return scratchDirectory.appending(component: "MyDependency")
   }
 
   private func runGitCommand(_ arguments: [String], workingDirectory: URL) async throws {
diff --git a/Sources/SKTestSupport/SwiftPMTestProject.swift b/Sources/SKTestSupport/SwiftPMTestProject.swift
index 23d7843ae..54e975ad5 100644
--- a/Sources/SKTestSupport/SwiftPMTestProject.swift
+++ b/Sources/SKTestSupport/SwiftPMTestProject.swift
@@ -53,7 +53,7 @@ package class SwiftPMTestProject: MultiFileTestProject {
         productsDirectory
           .deletingLastPathComponent()  // arm64-apple-macosx
           .deletingLastPathComponent()  // debug
-          .appendingPathComponent("checkouts"),
+          .appending(component: "checkouts"),
         URL(fileURLWithPath: #filePath)
           .deletingLastPathComponent()  // SwiftPMTestProject.swift
           .deletingLastPathComponent()  // SKTestSupport
@@ -64,11 +64,7 @@ package class SwiftPMTestProject: MultiFileTestProject {
       let swiftSyntaxCShimsModulemap =
         swiftSyntaxSearchPaths.map { swiftSyntaxSearchPath in
           swiftSyntaxSearchPath
-            .appendingPathComponent("swift-syntax")
-            .appendingPathComponent("Sources")
-            .appendingPathComponent("_SwiftSyntaxCShims")
-            .appendingPathComponent("include")
-            .appendingPathComponent("module.modulemap")
+            .appending(components: "swift-syntax", "Sources", "_SwiftSyntaxCShims", "include", "module.modulemap")
         }
         .first { FileManager.default.fileExists(at: $0) }
 
@@ -82,8 +78,7 @@ package class SwiftPMTestProject: MultiFileTestProject {
       // build folder wasn't cleaned and thus we would link against the stale `.o` file.
       let linkFileListURL =
         productsDirectory
-        .appendingPathComponent("SourceKitLSPPackageTests.product")
-        .appendingPathComponent("Objects.LinkFileList")
+        .appending(components: "SourceKitLSPPackageTests.product", "Objects.LinkFileList")
       let linkFileListContents = try? String(contentsOf: linkFileListURL, encoding: .utf8)
       guard let linkFileListContents else {
         struct LinkFileListNotFoundError: Swift.Error {
@@ -122,7 +117,7 @@ package class SwiftPMTestProject: MultiFileTestProject {
 
       var objectFiles: [String] = []
       for moduleName in swiftSyntaxModulesToLink {
-        let dir = productsDirectory.appendingPathComponent("\(moduleName).build")
+        let dir = productsDirectory.appending(component: "\(moduleName).build")
         let enumerator = FileManager.default.enumerator(at: dir, includingPropertiesForKeys: nil)
         while let file = enumerator?.nextObject() as? URL {
           if linkFileList.contains(try file.filePath) {
diff --git a/Sources/SKTestSupport/Utils.swift b/Sources/SKTestSupport/Utils.swift
index c0c34d507..fa6b7c538 100644
--- a/Sources/SKTestSupport/Utils.swift
+++ b/Sources/SKTestSupport/Utils.swift
@@ -84,8 +84,8 @@ package func testScratchDir(testName: String = #function) throws -> URL {
   #endif
 
   let url = try FileManager.default.temporaryDirectory.realpath
-    .appendingPathComponent(testScratchDirsName)
-    .appendingPathComponent(testScratchName(testName: testName), isDirectory: true)
+    .appending(component: testScratchDirsName)
+    .appending(component: testScratchName(testName: testName), directoryHint: .isDirectory)
 
   try? FileManager.default.removeItem(at: url)
   try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true)
@@ -120,7 +120,6 @@ var globalModuleCache: URL? {
       return URL(fileURLWithPath: customModuleCache)
     }
     return try FileManager.default.temporaryDirectory.realpath
-      .appendingPathComponent("sourcekit-lsp-test-scratch")
-      .appendingPathComponent("shared-module-cache")
+      .appending(components: "sourcekit-lsp-test-scratch", "shared-module-cache")
   }
 }
diff --git a/Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift b/Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift
index 9ccd2422f..0d6b91e00 100644
--- a/Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift
+++ b/Sources/SemanticIndex/UpdateIndexStoreTaskDescription.swift
@@ -756,8 +756,8 @@ fileprivate extension Process {
       }
 
       logger.debug("Argument list is too long. Using response file.")
-      let responseFile = FileManager.default.temporaryDirectory.appendingPathComponent(
-        "index-response-file-\(UUID()).txt"
+      let responseFile = FileManager.default.temporaryDirectory.appending(
+        component: "index-response-file-\(UUID()).txt"
       )
       defer {
         orLog("Failed to remove temporary response file") {
diff --git a/Sources/SourceKitLSP/SourceKitLSPServer.swift b/Sources/SourceKitLSP/SourceKitLSPServer.swift
index 4bec22b20..dd3c7b830 100644
--- a/Sources/SourceKitLSP/SourceKitLSPServer.swift
+++ b/Sources/SourceKitLSP/SourceKitLSPServer.swift
@@ -916,8 +916,7 @@ extension SourceKitLSPServer {
       base: self.options,
       override: SourceKitLSPOptions(
         path: workspaceFolder.fileURL?
-          .appendingPathComponent(".sourcekit-lsp")
-          .appendingPathComponent("config.json")
+          .appending(components: ".sourcekit-lsp", "config.json")
       )
     )
     logger.log("Creating workspace at \(workspaceFolder.forLogging)")
diff --git a/Sources/SwiftLanguageService/MacroExpansion.swift b/Sources/SwiftLanguageService/MacroExpansion.swift
index 64d05436b..38494d379 100644
--- a/Sources/SwiftLanguageService/MacroExpansion.swift
+++ b/Sources/SwiftLanguageService/MacroExpansion.swift
@@ -231,12 +231,11 @@ extension SwiftLanguageService {
       }
 
       var completeExpansionFilePath =
-        self.generatedMacroExpansionsPath.appendingPathComponent(
-          Insecure.MD5.hash(
-            data: Data(completeExpansionDirectoryName.utf8)
-          )
-          .map { String(format: "%02hhx", $0) }  // maps each byte of the hash to its hex equivalent `String`
-          .joined()
+        self.generatedMacroExpansionsPath.appending(
+          component:
+            Insecure.MD5.hash(data: Data(completeExpansionDirectoryName.utf8))
+            .map { String(format: "%02hhx", $0) }  // maps each byte of the hash to its hex equivalent `String`
+            .joined()
         )
 
       do {
@@ -251,7 +250,7 @@ extension SwiftLanguageService {
       }
 
       completeExpansionFilePath =
-        completeExpansionFilePath.appendingPathComponent(parentFileDisplayName)
+        completeExpansionFilePath.appending(component: parentFileDisplayName)
       do {
         try completeExpansionFileContent.write(to: completeExpansionFilePath, atomically: true, encoding: .utf8)
       } catch {
diff --git a/Sources/SwiftLanguageService/OpenInterface.swift b/Sources/SwiftLanguageService/OpenInterface.swift
index bfa6b1555..d6f9d402a 100644
--- a/Sources/SwiftLanguageService/OpenInterface.swift
+++ b/Sources/SwiftLanguageService/OpenInterface.swift
@@ -46,8 +46,7 @@ extension SwiftLanguageService {
       return GeneratedInterfaceDetails(uri: try urlData.uri, position: position)
     }
     let interfaceFilePath = self.generatedInterfacesPath
-      .appendingPathComponent(buildSettingsFileHash)
-      .appendingPathComponent(urlData.displayName)
+      .appending(components: buildSettingsFileHash, urlData.displayName)
     try FileManager.default.createDirectory(
       at: interfaceFilePath.deletingLastPathComponent(),
       withIntermediateDirectories: true
diff --git a/Sources/SwiftLanguageService/SwiftLanguageService.swift b/Sources/SwiftLanguageService/SwiftLanguageService.swift
index 87c84b8d8..728f6cbe6 100644
--- a/Sources/SwiftLanguageService/SwiftLanguageService.swift
+++ b/Sources/SwiftLanguageService/SwiftLanguageService.swift
@@ -119,12 +119,12 @@ package actor SwiftLanguageService: LanguageService, Sendable {
 
   /// Directory where generated Swift interfaces will be stored.
   var generatedInterfacesPath: URL {
-    options.generatedFilesAbsolutePath.appendingPathComponent("GeneratedInterfaces")
+    options.generatedFilesAbsolutePath.appending(component: "GeneratedInterfaces")
   }
 
   /// Directory where generated Macro expansions  will be stored.
   var generatedMacroExpansionsPath: URL {
-    options.generatedFilesAbsolutePath.appendingPathComponent("GeneratedMacroExpansions")
+    options.generatedFilesAbsolutePath.appending(component: "GeneratedMacroExpansions")
   }
 
   /// For each edited document, the last task that was triggered to send a `PublishDiagnosticsNotification`.
diff --git a/Sources/SwiftSourceKitPlugin/Plugin.swift b/Sources/SwiftSourceKitPlugin/Plugin.swift
index 10a873d38..29b2fcd19 100644
--- a/Sources/SwiftSourceKitPlugin/Plugin.swift
+++ b/Sources/SwiftSourceKitPlugin/Plugin.swift
@@ -191,16 +191,14 @@ private extension SourceKitD {
 
     let inProcUrl =
       frameworkUrl
-      .appendingPathComponent("sourcekitdInProc.framework")
-      .appendingPathComponent("sourcekitdInProc")
+      .appending(components: "sourcekitdInProc.framework", "sourcekitdInProc")
     if FileManager.default.fileExists(at: inProcUrl) {
       return try SourceKitD(dylib: inProcUrl, pluginPaths: nil, initialize: false)
     }
 
     let sourcekitdUrl =
       frameworkUrl
-      .appendingPathComponent("sourcekitd.framework")
-      .appendingPathComponent("sourcekitd")
+      .appending(components: "sourcekitd.framework", "sourcekitd")
     return try SourceKitD(dylib: sourcekitdUrl, pluginPaths: nil, initialize: false)
   }
 }
diff --git a/Sources/ToolchainRegistry/Toolchain.swift b/Sources/ToolchainRegistry/Toolchain.swift
index 61fabd1bc..fec13ca8e 100644
--- a/Sources/ToolchainRegistry/Toolchain.swift
+++ b/Sources/ToolchainRegistry/Toolchain.swift
@@ -297,10 +297,10 @@ public final class Toolchain: Sendable {
 
     var foundAny = false
     let searchPaths = [
-      path, path.appendingPathComponent("bin"), path.appendingPathComponent("usr").appendingPathComponent("bin"),
+      path, path.appending(component: "bin"), path.appending(components: "usr", "bin"),
     ]
     for binPath in searchPaths {
-      let libPath = binPath.deletingLastPathComponent().appendingPathComponent("lib")
+      let libPath = binPath.deletingLastPathComponent().appending(component: "lib")
 
       guard FileManager.default.isDirectory(at: binPath) || FileManager.default.isDirectory(at: libPath) else {
         continue
@@ -308,30 +308,30 @@ public final class Toolchain: Sendable {
 
       let execExt = Platform.current?.executableExtension ?? ""
 
-      let clangPath = binPath.appendingPathComponent("clang\(execExt)")
+      let clangPath = binPath.appending(component: "clang\(execExt)")
       if FileManager.default.isExecutableFile(atPath: clangPath.path) {
         clang = clangPath
         foundAny = true
       }
-      let clangdPath = binPath.appendingPathComponent("clangd\(execExt)")
+      let clangdPath = binPath.appending(component: "clangd\(execExt)")
       if FileManager.default.isExecutableFile(atPath: clangdPath.path) {
         clangd = clangdPath
         foundAny = true
       }
 
-      let swiftPath = binPath.appendingPathComponent("swift\(execExt)")
+      let swiftPath = binPath.appending(component: "swift\(execExt)")
       if FileManager.default.isExecutableFile(atPath: swiftPath.path) {
         swift = swiftPath
         foundAny = true
       }
 
-      let swiftcPath = binPath.appendingPathComponent("swiftc\(execExt)")
+      let swiftcPath = binPath.appending(component: "swiftc\(execExt)")
       if FileManager.default.isExecutableFile(atPath: swiftcPath.path) {
         swiftc = swiftcPath
         foundAny = true
       }
 
-      let swiftFormatPath = binPath.appendingPathComponent("swift-format\(execExt)")
+      let swiftFormatPath = binPath.appending(component: "swift-format\(execExt)")
       if FileManager.default.isExecutableFile(atPath: swiftFormatPath.path) {
         swiftFormat = swiftFormatPath
         foundAny = true
@@ -347,16 +347,16 @@ public final class Toolchain: Sendable {
       }
 
       func findDylib(named name: String, searchFramework: Bool = false) -> URL? {
-        let frameworkPath = libPath.appendingPathComponent("\(name).framework").appendingPathComponent(name)
+        let frameworkPath = libPath.appending(components: "\(name).framework", name)
         if FileManager.default.isFile(at: frameworkPath) {
           return frameworkPath
         }
-        let libSearchPath = libPath.appendingPathComponent("lib\(name)\(dylibExtension)")
+        let libSearchPath = libPath.appending(component: "lib\(name)\(dylibExtension)")
         if FileManager.default.isFile(at: libSearchPath) {
           return libSearchPath
         }
         #if os(Windows)
-        let binSearchPath = binPath.appendingPathComponent("\(name)\(dylibExtension)")
+        let binSearchPath = binPath.appending(component: "\(name)\(dylibExtension)")
         if FileManager.default.isFile(at: binSearchPath) {
           return binSearchPath
         }
@@ -382,9 +382,9 @@ public final class Toolchain: Sendable {
       }
 
       #if os(Windows)
-      let libIndexStorePath = binPath.appendingPathComponent("libIndexStore\(dylibExtension)")
+      let libIndexStorePath = binPath.appending(component: "libIndexStore\(dylibExtension)")
       #else
-      let libIndexStorePath = libPath.appendingPathComponent("libIndexStore\(dylibExtension)")
+      let libIndexStorePath = libPath.appending(component: "libIndexStore\(dylibExtension)")
       #endif
       if FileManager.default.isFile(at: libIndexStorePath) {
         libIndexStore = libIndexStorePath
diff --git a/Sources/ToolchainRegistry/ToolchainRegistry.swift b/Sources/ToolchainRegistry/ToolchainRegistry.swift
index f4d1665f8..cfa09b155 100644
--- a/Sources/ToolchainRegistry/ToolchainRegistry.swift
+++ b/Sources/ToolchainRegistry/ToolchainRegistry.swift
@@ -191,15 +191,13 @@ package final actor ToolchainRegistry {
     var toolchainSearchPaths =
       xcodes.map {
         if $0.pathExtension == "app" {
-          return $0.appendingPathComponent("Contents").appendingPathComponent("Developer").appendingPathComponent(
-            "Toolchains"
-          )
+          return $0.appending(components: "Contents", "Developer", "Toolchains")
         } else {
-          return $0.appendingPathComponent("Toolchains")
+          return $0.appending(component: "Toolchains")
         }
       }
     toolchainSearchPaths += libraryDirectories.compactMap {
-      $0.appendingPathComponent("Developer").appendingPathComponent("Toolchains")
+      $0.appending(components: "Developer", "Toolchains")
     }
 
     for xctoolchainSearchPath in toolchainSearchPaths {
diff --git a/Sources/sourcekit-lsp/SourceKitLSP.swift b/Sources/sourcekit-lsp/SourceKitLSP.swift
index a7869865c..ca8aa9648 100644
--- a/Sources/sourcekit-lsp/SourceKitLSP.swift
+++ b/Sources/sourcekit-lsp/SourceKitLSP.swift
@@ -180,8 +180,7 @@ struct SourceKitLSP: AsyncParsableCommand {
       base: commandLineOptions(),
       override: SourceKitLSPOptions(
         path: FileManager.default.homeDirectoryForCurrentUser
-          .appendingPathComponent(".sourcekit-lsp")
-          .appendingPathComponent("config.json")
+          .appending(components: ".sourcekit-lsp", "config.json")
       )
     )
     if Platform.current == .darwin {
@@ -191,8 +190,7 @@ struct SourceKitLSP: AsyncParsableCommand {
           override: SourceKitLSPOptions(
             path:
               applicationSupportDir
-              .appendingPathComponent("org.swift.sourcekit-lsp")
-              .appendingPathComponent("config.json")
+              .appending(components: "org.swift.sourcekit-lsp", "config.json")
           )
         )
       }
@@ -203,8 +201,7 @@ struct SourceKitLSP: AsyncParsableCommand {
         override: SourceKitLSPOptions(
           path:
             URL(fileURLWithPath: xdgConfigHome)
-            .appendingPathComponent("sourcekit-lsp")
-            .appendingPathComponent("config.json")
+            .appending(components: "sourcekit-lsp", "config.json")
         )
       )
     }
@@ -218,7 +215,7 @@ struct SourceKitLSP: AsyncParsableCommand {
     dateFormatter.timeZone = NSTimeZone.local
     let date = dateFormatter.string(from: Date()).replacingOccurrences(of: ":", with: "-")
 
-    let inputMirrorURL = directory.appendingPathComponent("\(date).log")
+    let inputMirrorURL = directory.appending(component: "\(date).log")
 
     logger.log("Mirroring input to \(inputMirrorURL)")
     try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
@@ -256,8 +253,7 @@ struct SourceKitLSP: AsyncParsableCommand {
 
     // Directory should match the directory we are searching for logs in `DiagnoseCommand.addNonDarwinLogs`.
     let logFileDirectoryURL = FileManager.default.homeDirectoryForCurrentUser
-      .appendingPathComponent(".sourcekit-lsp")
-      .appendingPathComponent("logs")
+      .appending(components: ".sourcekit-lsp", "logs")
     await setUpGlobalLogFileHandler(
       logFileDirectory: logFileDirectoryURL,
       logFileMaxBytes: 5_000_000,
diff --git a/Tests/BuildServerIntegrationTests/CompilationDatabaseTests.swift b/Tests/BuildServerIntegrationTests/CompilationDatabaseTests.swift
index 4b915c551..4aa86a77b 100644
--- a/Tests/BuildServerIntegrationTests/CompilationDatabaseTests.swift
+++ b/Tests/BuildServerIntegrationTests/CompilationDatabaseTests.swift
@@ -186,7 +186,7 @@ final class CompilationDatabaseTests: XCTestCase {
 
   func testJSONCompilationDatabaseFromDirectory() async throws {
     try await withTestScratchDir { tempDir in
-      let dbFile = tempDir.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+      let dbFile = tempDir.appending(component: JSONCompilationDatabaseBuildServer.dbName)
 
       XCTAssertThrowsError(try JSONCompilationDatabase(file: dbFile))
 
@@ -206,7 +206,7 @@ final class CompilationDatabaseTests: XCTestCase {
 
   func testFixedCompilationDatabase() async throws {
     try await withTestScratchDir { tempDir in
-      let dbFile = tempDir.appendingPathComponent(FixedCompilationDatabaseBuildServer.dbName)
+      let dbFile = tempDir.appending(component: FixedCompilationDatabaseBuildServer.dbName)
 
       XCTAssertThrowsError(
         try FixedCompilationDatabaseBuildServer(
@@ -228,7 +228,7 @@ final class CompilationDatabaseTests: XCTestCase {
         )
       )
 
-      let dummyFile = tempDir.appendingPathComponent("a.c")
+      let dummyFile = tempDir.appending(component: "a.c")
       let buildSettings = try await buildServer.sourceKitOptions(
         request: TextDocumentSourceKitOptionsRequest(
           textDocument: TextDocumentIdentifier(URI(dummyFile)),
@@ -248,7 +248,7 @@ final class CompilationDatabaseTests: XCTestCase {
 
   func testInvalidCompilationDatabase() async throws {
     try await withTestScratchDir { tempDir in
-      let dbFile = tempDir.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+      let dbFile = tempDir.appending(component: JSONCompilationDatabaseBuildServer.dbName)
 
       try "".write(to: dbFile, atomically: true, encoding: .utf8)
       XCTAssertThrowsError(try JSONCompilationDatabase(file: dbFile))
@@ -436,7 +436,7 @@ private func checkCompilationDatabaseBuildServer(
   block: @Sendable (JSONCompilationDatabaseBuildServer) async throws -> Void
 ) async throws {
   try await withTestScratchDir { tempDir in
-    let configPath = tempDir.appendingPathComponent(JSONCompilationDatabaseBuildServer.dbName)
+    let configPath = tempDir.appending(component: JSONCompilationDatabaseBuildServer.dbName)
     try compdb.write(to: configPath, atomically: true, encoding: .utf8)
     let buildServer = try JSONCompilationDatabaseBuildServer(
       configPath: configPath,
diff --git a/Tests/BuildServerIntegrationTests/ExternalBuildServerTests.swift b/Tests/BuildServerIntegrationTests/ExternalBuildServerTests.swift
index f7db89d4e..dc1de6bf3 100644
--- a/Tests/BuildServerIntegrationTests/ExternalBuildServerTests.swift
+++ b/Tests/BuildServerIntegrationTests/ExternalBuildServerTests.swift
@@ -311,7 +311,7 @@ final class ExternalBuildServerTests: XCTestCase {
       DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri))
     )
     XCTAssertEqual(diagnosticsBeforeCrash.fullReport?.items, [])
-    try FileManager.default.removeItem(at: project.scratchDirectory.appendingPathComponent("should_crash"))
+    try FileManager.default.removeItem(at: project.scratchDirectory.appending(component: "should_crash"))
 
     try await repeatUntilExpectedResult(timeout: .seconds(20)) {
       let diagnostics = try await project.testClient.send(
@@ -611,7 +611,7 @@ final class ExternalBuildServerTests: XCTestCase {
       }
 
       func buildTargetSourcesRequest(_ request: BuildTargetSourcesRequest) -> BuildTargetSourcesResponse {
-        return dummyTargetSourcesResponse(files: [DocumentURI(projectRoot.appendingPathComponent("Test.swift"))])
+        return dummyTargetSourcesResponse(files: [DocumentURI(projectRoot.appending(component: "Test.swift"))])
       }
 
       func textDocumentSourceKitOptionsRequest(
@@ -720,7 +720,7 @@ final class ExternalBuildServerTests: XCTestCase {
         didReceiveTargetSourcesRequest = true
 
         await unlockBuildServerResponses.waitOrXCTFail()
-        return dummyTargetSourcesResponse(files: [DocumentURI(projectRoot.appendingPathComponent("Test.swift"))])
+        return dummyTargetSourcesResponse(files: [DocumentURI(projectRoot.appending(component: "Test.swift"))])
       }
 
       func textDocumentSourceKitOptionsRequest(
diff --git a/Tests/BuildServerIntegrationTests/SwiftPMBuildServerTests.swift b/Tests/BuildServerIntegrationTests/SwiftPMBuildServerTests.swift
index 3d52ea35f..20e2e50b5 100644
--- a/Tests/BuildServerIntegrationTests/SwiftPMBuildServerTests.swift
+++ b/Tests/BuildServerIntegrationTests/SwiftPMBuildServerTests.swift
@@ -56,7 +56,7 @@ struct SwiftPMBuildServerTests {
           "pkg/Sources/lib/a.swift": ""
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       let buildServerSpec = SwiftPMBuildServer.searchForConfig(in: packageRoot, options: try await .testDefault())
       #expect(buildServerSpec == nil)
     }
@@ -79,7 +79,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       await expectThrowsError(
         try await SwiftPMBuildServer(
           projectRoot: packageRoot,
@@ -125,7 +125,7 @@ struct SwiftPMBuildServerTests {
       )
 
       let dataPath = await swiftpmBuildServer.destinationBuildParameters.dataPath
-      let expectedScratchPath = packageRoot.appendingPathComponent(try #require(options.swiftPMOrDefault.scratchPath))
+      let expectedScratchPath = packageRoot.appending(component: try #require(options.swiftPMOrDefault.scratchPath))
       #expect(dataPath.asURL.isDescendant(of: expectedScratchPath))
     }
   }
@@ -147,7 +147,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -159,9 +159,7 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
       let build = try await buildPath(root: packageRoot, platform: hostTriple.platformBuildPathComponent)
 
       _ = try #require(await buildServerManager.initializationData?.indexDatabasePath)
@@ -191,7 +189,7 @@ struct SwiftPMBuildServerTests {
       expectArgumentsContain("-target", try await hostTriple.tripleString, arguments: arguments)
       #endif
 
-      expectArgumentsContain("-I", try build.appendingPathComponent("Modules").filePath, arguments: arguments)
+      expectArgumentsContain("-I", try build.appending(component: "Modules").filePath, arguments: arguments)
 
       expectArgumentsContain(try aswift.filePath, arguments: arguments)
     }
@@ -215,7 +213,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -227,9 +225,7 @@ struct SwiftPMBuildServerTests {
 
       let aPlusSomething =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a+something.swift")
+        .appending(components: "Sources", "lib", "a+something.swift")
 
       _ = try #require(await buildServerManager.initializationData?.indexStorePath)
       let pathWithPlusEscaped = "\(try aPlusSomething.filePath.replacing("+", with: "%2B"))"
@@ -255,7 +251,7 @@ struct SwiftPMBuildServerTests {
       )
       #expect(
         try arguments.contains(
-          packageRoot.appendingPathComponent("Sources").appendingPathComponent("lib").appendingPathComponent("a.swift")
+          packageRoot.appending(components: "Sources", "lib", "a.swift")
             .filePath
         ),
         "Compiler arguments do not contain a.swift: \(arguments)"
@@ -280,11 +276,11 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
 
       let options = SourceKitLSPOptions.SwiftPMOptions(
         configuration: .release,
-        scratchPath: try packageRoot.appendingPathComponent("non_default_build_path").filePath,
+        scratchPath: try packageRoot.appending(component: "non_default_build_path").filePath,
         cCompilerFlags: ["-m32"],
         swiftCompilerFlags: ["-typecheck"]
       )
@@ -300,9 +296,7 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
 
       let arguments = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
@@ -335,7 +329,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -345,7 +339,7 @@ struct SwiftPMBuildServerTests {
       )
       await buildServerManager.waitForUpToDateBuildGraph()
 
-      let source = try packageRoot.appendingPathComponent("Package.swift").realpath
+      let source = try packageRoot.appending(component: "Package.swift").realpath
       let arguments = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
           for: DocumentURI(source),
@@ -376,7 +370,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -388,14 +382,10 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
       let bswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("b.swift")
+        .appending(components: "Sources", "lib", "b.swift")
 
       let argumentsA = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
@@ -442,7 +432,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -454,14 +444,10 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("libA")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "libA", "a.swift")
       let bswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("libB")
-        .appendingPathComponent("b.swift")
+        .appending(components: "Sources", "libB", "b.swift")
       let arguments = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
           for: DocumentURI(aswift),
@@ -476,9 +462,7 @@ struct SwiftPMBuildServerTests {
         "-I",
         "-Xcc",
         try packageRoot
-          .appendingPathComponent("Sources")
-          .appendingPathComponent("libC")
-          .appendingPathComponent("include")
+          .appending(components: "Sources", "libC", "include")
           .filePath,
         arguments: arguments
       )
@@ -495,9 +479,7 @@ struct SwiftPMBuildServerTests {
       expectArgumentsDoNotContain(
         "-I",
         try packageRoot
-          .appendingPathComponent("Sources")
-          .appendingPathComponent("libC")
-          .appendingPathComponent("include")
+          .appending(components: "Sources", "libC", "include")
           .filePath,
         arguments: argumentsB
       )
@@ -522,7 +504,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -534,14 +516,10 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("libA")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "libA", "a.swift")
       let bswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("libB")
-        .appendingPathComponent("b.swift")
+        .appending(components: "Sources", "libB", "b.swift")
       _ = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
           for: DocumentURI(aswift),
@@ -586,7 +564,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -598,20 +576,13 @@ struct SwiftPMBuildServerTests {
 
       let acxx =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.cpp")
+        .appending(components: "Sources", "lib", "a.cpp")
       let bcxx =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("b.cpp")
+        .appending(components: "Sources", "lib", "b.cpp")
       let header =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("include")
-        .appendingPathComponent("a.h")
+        .appending(components: "Sources", "lib", "include", "a.h")
       let build = buildPath(root: packageRoot, platform: try await hostTriple.platformBuildPathComponent)
 
       _ = try #require(await buildServerManager.initializationData?.indexStorePath)
@@ -645,16 +616,14 @@ struct SwiftPMBuildServerTests {
         expectArgumentsContain(
           "-I",
           try packageRoot
-            .appendingPathComponent("Sources")
-            .appendingPathComponent("lib")
-            .appendingPathComponent("include")
+            .appending(components: "Sources", "lib", "include")
             .filePath,
           arguments: args
         )
         expectArgumentsDoNotContain("-I", try build.filePath, arguments: args)
         expectArgumentsDoNotContain(try bcxx.filePath, arguments: args)
 
-        URL(fileURLWithPath: try build.appendingPathComponent("lib.build").appendingPathComponent("a.cpp.o").filePath)
+        URL(fileURLWithPath: try build.appending(components: "lib.build", "a.cpp.o").filePath)
           .withUnsafeFileSystemRepresentation {
             expectArgumentsContain("-o", String(cString: $0!), arguments: args)
           }
@@ -679,7 +648,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -691,9 +660,7 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
       let arguments = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
           for: DocumentURI(aswift),
@@ -732,11 +699,11 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
 
       try FileManager.default.createSymbolicLink(
         at: URL(fileURLWithPath: packageRoot.filePath),
-        withDestinationURL: URL(fileURLWithPath: tempDir.appendingPathComponent("pkg_real").filePath)
+        withDestinationURL: URL(fileURLWithPath: tempDir.appending(component: "pkg_real").filePath)
       )
 
       let buildServerSpec = try #require(
@@ -753,11 +720,9 @@ struct SwiftPMBuildServerTests {
 
       let aswiftSymlink =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
       let aswiftReal = try aswiftSymlink.realpath
-      let manifest = packageRoot.appendingPathComponent("Package.swift")
+      let manifest = packageRoot.appending(component: "Package.swift")
 
       let argumentsFromSymlink = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
@@ -818,12 +783,12 @@ struct SwiftPMBuildServerTests {
       let acpp = ["Sources", "lib", "a.cpp"]
       let ah = ["Sources", "lib", "include", "a.h"]
 
-      let realRoot = tempDir.appendingPathComponent("pkg_real")
-      let symlinkRoot = tempDir.appendingPathComponent("pkg")
+      let realRoot = tempDir.appending(component: "pkg_real")
+      let symlinkRoot = tempDir.appending(component: "pkg")
 
       try FileManager.default.createSymbolicLink(
         at: URL(fileURLWithPath: symlinkRoot.filePath),
-        withDestinationURL: URL(fileURLWithPath: tempDir.appendingPathComponent("pkg_real").filePath)
+        withDestinationURL: URL(fileURLWithPath: tempDir.appending(component: "pkg_real").filePath)
       )
 
       let buildServerSpec = try #require(
@@ -871,7 +836,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -883,9 +848,7 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Sources", "lib", "a.swift")
       let arguments = try #require(
         await buildServerManager.buildSettingsInferredFromMainFile(
           for: DocumentURI(aswift),
@@ -923,9 +886,7 @@ struct SwiftPMBuildServerTests {
       )
       let workspaceRoot =
         tempDir
-        .appendingPathComponent("pkg")
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("lib")
+        .appending(components: "pkg", "Sources", "lib")
 
       let buildServerSpec = SwiftPMBuildServer.searchForConfig(in: workspaceRoot, options: try await .testDefault())
       #expect(buildServerSpec == nil)
@@ -953,7 +914,7 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = tempDir.appendingPathComponent("pkg")
+      let packageRoot = tempDir.appending(component: "pkg")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -965,9 +926,7 @@ struct SwiftPMBuildServerTests {
 
       let aswift =
         packageRoot
-        .appendingPathComponent("Plugins")
-        .appendingPathComponent("MyPlugin")
-        .appendingPathComponent("a.swift")
+        .appending(components: "Plugins", "MyPlugin", "a.swift")
 
       _ = try #require(await buildServerManager.initializationData?.indexStorePath)
       let arguments = try #require(
@@ -1081,8 +1040,8 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
-      let versionSpecificManifestURL = packageRoot.appendingPathComponent("Package@swift-5.8.swift")
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
+      let versionSpecificManifestURL = packageRoot.appending(component: "Package@swift-5.8.swift")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -1115,8 +1074,8 @@ struct SwiftPMBuildServerTests {
           """,
         ]
       )
-      let packageRoot = try tempDir.appendingPathComponent("pkg").realpath
-      let manifestURL = packageRoot.appendingPathComponent("Package.swift")
+      let packageRoot = try tempDir.appending(component: "pkg").realpath
+      let manifestURL = packageRoot.appending(component: "Package.swift")
       let buildServerManager = await BuildServerManager(
         buildServerSpec: .swiftpmSpec(for: packageRoot),
         toolchainRegistry: .forTesting,
@@ -1179,9 +1138,9 @@ private func buildPath(
     if let scratchPath = options.scratchPath {
       URL(fileURLWithPath: scratchPath)
     } else {
-      root.appendingPathComponent(".build").appendingPathComponent("index-build")
+      root.appending(components: ".build", "index-build")
     }
-  return buildPath.appendingPathComponent(platform).appendingPathComponent("\(options.configuration ?? .debug)")
+  return buildPath.appending(components: platform, "\(options.configuration ?? .debug)")
 }
 
 fileprivate extension URL {
@@ -1199,7 +1158,7 @@ fileprivate extension BuildServerSpec {
     return BuildServerSpec(
       kind: .swiftPM,
       projectRoot: packageRoot,
-      configPath: packageRoot.appendingPathComponent("Package.swift")
+      configPath: packageRoot.appending(component: "Package.swift")
     )
   }
 }
diff --git a/Tests/DiagnoseTests/DiagnoseTests.swift b/Tests/DiagnoseTests/DiagnoseTests.swift
index 2650faa17..6fc1aa7df 100644
--- a/Tests/DiagnoseTests/DiagnoseTests.swift
+++ b/Tests/DiagnoseTests/DiagnoseTests.swift
@@ -161,8 +161,8 @@ final class DiagnoseTests: XCTestCase {
         func unrelatedB() {}
         """
 
-      let fileAPath = try scratchDir.appendingPathComponent("a.swift").filePath
-      let fileBPath = try scratchDir.appendingPathComponent("b.swift").filePath
+      let fileAPath = try scratchDir.appending(component: "a.swift").filePath
+      let fileBPath = try scratchDir.appending(component: "b.swift").filePath
 
       try fileAContents.write(toFile: fileAPath, atomically: true, encoding: .utf8)
       try fileBContents.write(toFile: fileBPath, atomically: true, encoding: .utf8)
@@ -250,7 +250,7 @@ private func assertReduceSourceKitD(
         reproducerPredicate(requestResponse as! String)
       })
     )
-    let testFilePath = try scratchDir.appendingPathComponent("test.swift").filePath
+    let testFilePath = try scratchDir.appending(component: "test.swift").filePath
     try fileContents.write(toFile: testFilePath, atomically: false, encoding: .utf8)
 
     let request =
@@ -295,8 +295,8 @@ private class InProcessSourceKitRequestExecutor: SourceKitRequestExecutor {
     self.sourcekitd = try XCTUnwrap(toolchain.sourcekitd)
     self.swiftFrontend = try XCTUnwrap(toolchain.swiftFrontend)
     self.reproducerPredicate = reproducerPredicate
-    temporaryRequestFile = FileManager.default.temporaryDirectory.appendingPathComponent("request-\(UUID()).yml")
-    temporarySourceFile = FileManager.default.temporaryDirectory.appendingPathComponent("reduce-\(UUID()).swift")
+    temporaryRequestFile = FileManager.default.temporaryDirectory.appending(component: "request-\(UUID()).yml")
+    temporarySourceFile = FileManager.default.temporaryDirectory.appending(component: "reduce-\(UUID()).swift")
   }
 
   deinit {
diff --git a/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift b/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
index 7360ae9c6..465f66dac 100644
--- a/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
+++ b/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
@@ -248,8 +248,7 @@ final class BackgroundIndexingTests: XCTestCase {
     let dependencyUrl = try XCTUnwrap(
       FileManager.default.findFiles(
         named: "MyDependency.swift",
-        in: project.scratchDirectory.appendingPathComponent(".build").appendingPathComponent("index-build")
-          .appendingPathComponent("checkouts")
+        in: project.scratchDirectory.appending(components: ".build", "index-build", "checkouts")
       ).only
     )
     let dependencyUri = DocumentURI(dependencyUrl)
@@ -894,8 +893,7 @@ final class BackgroundIndexingTests: XCTestCase {
     let nestedIndexBuildURL = try XCTUnwrap(
       project.uri(for: "OtherLib.swift").fileURL?
         .deletingLastPathComponent()
-        .appendingPathComponent(".build")
-        .appendingPathComponent("index-build")
+        .appending(components: ".build", "index-build")
     )
     XCTAssertFalse(
       FileManager.default.fileExists(at: nestedIndexBuildURL),
@@ -1263,9 +1261,7 @@ final class BackgroundIndexingTests: XCTestCase {
       """
     ])
     let dependencySwiftURL = dependencyProject.packageDirectory
-      .appendingPathComponent("Sources")
-      .appendingPathComponent("MyDependency")
-      .appendingPathComponent("Dependency.swift")
+      .appending(components: "Sources", "MyDependency", "Dependency.swift")
     defer { dependencyProject.keepAlive() }
 
     let project = try await SwiftPMTestProject(
@@ -1292,7 +1288,7 @@ final class BackgroundIndexingTests: XCTestCase {
         """,
       enableBackgroundIndexing: true
     )
-    let packageResolvedURL = project.scratchDirectory.appendingPathComponent("Package.resolved")
+    let packageResolvedURL = project.scratchDirectory.appending(component: "Package.resolved")
 
     let originalPackageResolvedContents = try String(contentsOf: packageResolvedURL, encoding: .utf8)
 
@@ -1325,7 +1321,7 @@ final class BackgroundIndexingTests: XCTestCase {
     // Updating Package.swift causes a package reload but should not cause dependencies to be updated.
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [
-        FileEvent(uri: DocumentURI(project.scratchDirectory.appendingPathComponent("Package.swift")), type: .changed)
+        FileEvent(uri: DocumentURI(project.scratchDirectory.appending(component: "Package.swift")), type: .changed)
       ])
     )
     try await project.testClient.send(SynchronizeRequest(index: true))
@@ -1356,7 +1352,7 @@ final class BackgroundIndexingTests: XCTestCase {
     XCTAssertNotEqual(try String(contentsOf: packageResolvedURL, encoding: .utf8), originalPackageResolvedContents)
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [
-        FileEvent(uri: DocumentURI(project.scratchDirectory.appendingPathComponent("Package.resolved")), type: .changed)
+        FileEvent(uri: DocumentURI(project.scratchDirectory.appending(component: "Package.resolved")), type: .changed)
       ])
     )
     try await project.testClient.send(SynchronizeRequest(index: true))
@@ -1364,9 +1360,7 @@ final class BackgroundIndexingTests: XCTestCase {
       FileManager.default.findFiles(
         named: "Dependency.swift",
         in: project.scratchDirectory
-          .appendingPathComponent(".build")
-          .appendingPathComponent("index-build")
-          .appendingPathComponent("checkouts")
+          .appending(components: ".build", "index-build", "checkouts")
       ).only
     )
     // Check that modifying Package.resolved actually modified the dependency checkout inside the package
@@ -1400,7 +1394,7 @@ final class BackgroundIndexingTests: XCTestCase {
     packageInitialized.value = true
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [
-        FileEvent(uri: DocumentURI(project.scratchDirectory.appendingPathComponent("random.swift")), type: .created)
+        FileEvent(uri: DocumentURI(project.scratchDirectory.appending(component: "random.swift")), type: .created)
       ])
     )
     _ = try await project.testClient.send(SynchronizeRequest(index: true))
@@ -1570,12 +1564,10 @@ final class BackgroundIndexingTests: XCTestCase {
       workspaces: { scratchDirectory in
         let symlink =
           scratchDirectory
-          .appendingPathComponent("Sources")
-          .appendingPathComponent("MyLibrary")
-          .appendingPathComponent("symlink.swift")
+          .appending(components: "Sources", "MyLibrary", "symlink.swift")
         try FileManager.default.createSymbolicLink(
           at: symlink,
-          withDestinationURL: scratchDirectory.appendingPathComponent("original.swift")
+          withDestinationURL: scratchDirectory.appending(component: "original.swift")
         )
         return [WorkspaceFolder(uri: DocumentURI(scratchDirectory))]
       },
@@ -1593,13 +1585,11 @@ final class BackgroundIndexingTests: XCTestCase {
 
     let symlink =
       project.scratchDirectory
-      .appendingPathComponent("Sources")
-      .appendingPathComponent("MyLibrary")
-      .appendingPathComponent("symlink.swift")
+      .appending(components: "Sources", "MyLibrary", "symlink.swift")
     try FileManager.default.removeItem(at: symlink)
     try FileManager.default.createSymbolicLink(
       at: symlink,
-      withDestinationURL: project.scratchDirectory.appendingPathComponent("updated.swift")
+      withDestinationURL: project.scratchDirectory.appending(component: "updated.swift")
     )
 
     project.testClient.send(
@@ -1747,10 +1737,10 @@ final class BackgroundIndexingTests: XCTestCase {
         )
         """,
       workspaces: { scratchDirectory in
-        let sources = scratchDirectory.appendingPathComponent("Sources")
+        let sources = scratchDirectory.appending(component: "Sources")
         try FileManager.default.createSymbolicLink(
-          at: sources.appendingPathComponent("LibASymlink"),
-          withDestinationURL: sources.appendingPathComponent("LibA")
+          at: sources.appending(component: "LibASymlink"),
+          withDestinationURL: sources.appending(component: "LibA")
         )
         return [WorkspaceFolder(uri: DocumentURI(scratchDirectory))]
       },
@@ -2091,7 +2081,7 @@ final class BackgroundIndexingTests: XCTestCase {
     final class BuildServer: CustomBuildServer {
       let inProgressRequestsTracker = CustomBuildServerInProgressRequestTracker()
       private let projectRoot: URL
-      private var testFileURL: URL { projectRoot.appendingPathComponent("Test File.swift") }
+      private var testFileURL: URL { projectRoot.appending(component: "Test File.swift") }
 
       init(projectRoot: URL, connectionToSourceKitLSP: any LanguageServerProtocol.Connection) {
         self.projectRoot = projectRoot
@@ -2100,8 +2090,8 @@ final class BackgroundIndexingTests: XCTestCase {
       func initializeBuildRequest(_ request: InitializeBuildRequest) async throws -> InitializeBuildResponse {
         return initializationResponse(
           initializeData: SourceKitInitializeBuildResponseData(
-            indexDatabasePath: try projectRoot.appendingPathComponent("index-db").filePath,
-            indexStorePath: try projectRoot.appendingPathComponent("index-store").filePath,
+            indexDatabasePath: try projectRoot.appending(component: "index-db").filePath,
+            indexStorePath: try projectRoot.appending(component: "index-store").filePath,
             prepareProvider: true,
             sourceKitOptionsProvider: true
           )
@@ -2215,7 +2205,7 @@ final class BackgroundIndexingTests: XCTestCase {
     final class BuildServer: CustomBuildServer {
       let inProgressRequestsTracker = CustomBuildServerInProgressRequestTracker()
       private let projectRoot: URL
-      private var testFileURL: URL { projectRoot.appendingPathComponent("test.c").standardized }
+      private var testFileURL: URL { projectRoot.appending(component: "test.c").standardized }
 
       required init(projectRoot: URL, connectionToSourceKitLSP: any LanguageServerProtocol.Connection) {
         self.projectRoot = projectRoot
@@ -2242,8 +2232,7 @@ final class BackgroundIndexingTests: XCTestCase {
     }
 
     let scratchDirectory = URL(fileURLWithPath: "/tmp")
-      .appendingPathComponent("sourcekitlsp-test")
-      .appendingPathComponent(testScratchName())
+      .appending(components: "sourcekitlsp-test", testScratchName())
     let indexedFiles = ThreadSafeBox<[DocumentURI]>(initialValue: [])
     let project = try await CustomBuildServerTestProject(
       files: [
@@ -2290,11 +2279,11 @@ final class BackgroundIndexingTests: XCTestCase {
             target: libATarget,
             sources: [
               sourceItem(
-                for: projectRoot.appendingPathComponent("Shared.swift"),
+                for: projectRoot.appending(component: "Shared.swift"),
                 outputPath: fakeOutputPath(for: "Shared.swift", in: "LibA")
               ),
               sourceItem(
-                for: projectRoot.appendingPathComponent("LibA.swift"),
+                for: projectRoot.appending(component: "LibA.swift"),
                 outputPath: fakeOutputPath(for: "LibA.swift", in: "LibA")
               ),
             ]
@@ -2303,11 +2292,11 @@ final class BackgroundIndexingTests: XCTestCase {
             target: libBTarget,
             sources: [
               sourceItem(
-                for: projectRoot.appendingPathComponent("Shared.swift"),
+                for: projectRoot.appending(component: "Shared.swift"),
                 outputPath: fakeOutputPath(for: "Shared.swift", in: "LibB")
               ),
               sourceItem(
-                for: projectRoot.appendingPathComponent("LibB.swift"),
+                for: projectRoot.appending(component: "LibB.swift"),
                 outputPath: fakeOutputPath(for: "LibB.swift", in: "LibB")
               ),
             ]
@@ -2407,7 +2396,7 @@ final class BackgroundIndexingTests: XCTestCase {
             target: libATarget,
             sources: [
               sourceItem(
-                for: projectRoot.appendingPathComponent("LibA.c"),
+                for: projectRoot.appending(component: "LibA.c"),
                 outputPath: fakeOutputPath(for: "LibA.c", in: "LibA")
               )
             ]
@@ -2416,7 +2405,7 @@ final class BackgroundIndexingTests: XCTestCase {
             target: libBTarget,
             sources: [
               sourceItem(
-                for: projectRoot.appendingPathComponent("LibB.c"),
+                for: projectRoot.appending(component: "LibB.c"),
                 outputPath: fakeOutputPath(for: "LibB.c", in: "LibB")
               )
             ]
@@ -2557,7 +2546,7 @@ final class BackgroundIndexingTests: XCTestCase {
             target: .dummy,
             sources: [
               sourceItem(
-                for: projectRoot.appendingPathComponent("test.swift"),
+                for: projectRoot.appending(component: "test.swift"),
                 outputPath: fakeOutputPath(for: "test.swift", in: "dummy")
               )
             ]
diff --git a/Tests/SourceKitLSPTests/CompilationDatabaseTests.swift b/Tests/SourceKitLSPTests/CompilationDatabaseTests.swift
index f4c5dead8..c3c16290c 100644
--- a/Tests/SourceKitLSPTests/CompilationDatabaseTests.swift
+++ b/Tests/SourceKitLSPTests/CompilationDatabaseTests.swift
@@ -272,8 +272,8 @@ final class CompilationDatabaseTests: XCTestCase {
 
       // Create a dummy swiftly executable that picks the default toolchain for all file unless `fakeToolchain` is in
       // the source file's path.
-      let dummySwiftlyExecutableUrl = scratchDirectory.appendingPathComponent("swiftly")
-      let dummySwiftExecutableUrl = scratchDirectory.appendingPathComponent("swift")
+      let dummySwiftlyExecutableUrl = scratchDirectory.appending(component: "swiftly")
+      let dummySwiftExecutableUrl = scratchDirectory.appending(component: "swift")
       try FileManager.default.createSymbolicLink(
         at: dummySwiftExecutableUrl,
         withDestinationURL: dummySwiftlyExecutableUrl
diff --git a/Tests/SourceKitLSPTests/DefinitionTests.swift b/Tests/SourceKitLSPTests/DefinitionTests.swift
index f87213230..fd3ecfefe 100644
--- a/Tests/SourceKitLSPTests/DefinitionTests.swift
+++ b/Tests/SourceKitLSPTests/DefinitionTests.swift
@@ -486,7 +486,7 @@ class DefinitionTests: XCTestCase {
       DocumentURI(
         definitionUri.fileURL!
           .deletingLastPathComponent()
-          .appendingPathComponent("movedDefinition.swift")
+          .appending(component: "movedDefinition.swift")
       )
 
     try FileManager.default.moveItem(at: XCTUnwrap(definitionUri.fileURL), to: XCTUnwrap(movedDefinitionUri.fileURL))
@@ -616,7 +616,7 @@ class DefinitionTests: XCTestCase {
             target: .dummy,
             sources: [
               SourceItem(
-                uri: DocumentURI(projectRoot.appendingPathComponent("Test.c")),
+                uri: DocumentURI(projectRoot.appending(component: "Test.c")),
                 kind: .file,
                 generated: false,
                 dataKind: .sourceKit,
@@ -628,7 +628,7 @@ class DefinitionTests: XCTestCase {
                 ).encodeToLSPAny()
               ),
               SourceItem(
-                uri: DocumentURI(projectRoot.appendingPathComponent("Test.h")),
+                uri: DocumentURI(projectRoot.appending(component: "Test.h")),
                 kind: .file,
                 generated: false,
                 dataKind: .sourceKit,
diff --git a/Tests/SourceKitLSPTests/DependencyTrackingTests.swift b/Tests/SourceKitLSPTests/DependencyTrackingTests.swift
index 767560ddb..f448d3c11 100644
--- a/Tests/SourceKitLSPTests/DependencyTrackingTests.swift
+++ b/Tests/SourceKitLSPTests/DependencyTrackingTests.swift
@@ -94,7 +94,7 @@ final class DependencyTrackingTests: XCTestCase {
     )
 
     let generatedHeaderURL = try project.uri(for: "main.c").fileURL!.deletingLastPathComponent()
-      .appendingPathComponent("lib-generated.h", isDirectory: false)
+      .appending(component: "lib-generated.h")
 
     // Write an empty header file first since clangd doesn't handle missing header
     // files without a recently upstreamed extension.
diff --git a/Tests/SourceKitLSPTests/FormattingTests.swift b/Tests/SourceKitLSPTests/FormattingTests.swift
index 806153199..4b252bc44 100644
--- a/Tests/SourceKitLSPTests/FormattingTests.swift
+++ b/Tests/SourceKitLSPTests/FormattingTests.swift
@@ -313,7 +313,7 @@ final class FormattingTests: XCTestCase {
     try await withTestScratchDir { scratchDir in
       let toolchain = try await unwrap(ToolchainRegistry.forTesting.default)
 
-      let crashingExecutablePath = scratchDir.appendingPathComponent("crashing-executable")
+      let crashingExecutablePath = scratchDir.appending(component: "crashing-executable")
       try await createBinary(
         """
         fatalError()
diff --git a/Tests/SourceKitLSPTests/IndexTests.swift b/Tests/SourceKitLSPTests/IndexTests.swift
index e0cb79477..42d73fa24 100644
--- a/Tests/SourceKitLSPTests/IndexTests.swift
+++ b/Tests/SourceKitLSPTests/IndexTests.swift
@@ -128,7 +128,7 @@ final class IndexTests: XCTestCase {
       XCTAssertEqual(jump.first?.uri, project.fileURI)
       XCTAssertEqual(jump.first?.range.lowerBound, project.positions["1️⃣"])
 
-      let indexDBURL = project.fileURI.fileURL!.deletingLastPathComponent().appendingPathComponent("IndexDatabase")
+      let indexDBURL = project.fileURI.fileURL!.deletingLastPathComponent().appending(component: "IndexDatabase")
       let tmpContents = try listdir(indexDBURL)
       guard let versionedPath = tmpContents.filter({ $0.lastPathComponent.starts(with: "v") }).only else {
         XCTFail("expected one version path 'v[0-9]*', found \(tmpContents)")
diff --git a/Tests/SourceKitLSPTests/PullDiagnosticsTests.swift b/Tests/SourceKitLSPTests/PullDiagnosticsTests.swift
index b24d60b18..ecabac28a 100644
--- a/Tests/SourceKitLSPTests/PullDiagnosticsTests.swift
+++ b/Tests/SourceKitLSPTests/PullDiagnosticsTests.swift
@@ -425,7 +425,7 @@ final class PullDiagnosticsTests: XCTestCase {
     let project = try await SwiftPMTestProject(
       files: ["FileA.swift": contents],
       workspaces: { scratchDirectory in
-        let symlinkUrl = scratchDirectory.appendingPathComponent("symlink")
+        let symlinkUrl = scratchDirectory.appending(component: "symlink")
         try FileManager.default.createSymbolicLink(
           at: symlinkUrl,
           withDestinationURL: scratchDirectory
@@ -436,10 +436,7 @@ final class PullDiagnosticsTests: XCTestCase {
 
     let uri = DocumentURI(
       project.scratchDirectory
-        .appendingPathComponent("symlink")
-        .appendingPathComponent("Sources")
-        .appendingPathComponent("MyLibrary")
-        .appendingPathComponent("FileA.swift")
+        .appending(components: "symlink", "Sources", "MyLibrary", "FileA.swift")
     )
     project.testClient.send(
       DidOpenTextDocumentNotification(
diff --git a/Tests/SourceKitLSPTests/RenameTests.swift b/Tests/SourceKitLSPTests/RenameTests.swift
index 82e0bde8d..9935389ac 100644
--- a/Tests/SourceKitLSPTests/RenameTests.swift
+++ b/Tests/SourceKitLSPTests/RenameTests.swift
@@ -1129,7 +1129,7 @@ final class RenameTests: XCTestCase {
       DocumentURI(
         definitionUri.fileURL!
           .deletingLastPathComponent()
-          .appendingPathComponent("movedDefinition.swift")
+          .appending(component: "movedDefinition.swift")
       )
 
     try FileManager.default.moveItem(at: XCTUnwrap(definitionUri.fileURL), to: XCTUnwrap(movedDefinitionUri.fileURL))
diff --git a/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift b/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
index 2404829ef..e17a5adc3 100644
--- a/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
+++ b/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
@@ -112,9 +112,7 @@ final class SwiftPMIntegrationTests: XCTestCase {
     )
 
     let newFileUrl = project.scratchDirectory
-      .appendingPathComponent("Sources")
-      .appendingPathComponent("MyLibrary")
-      .appendingPathComponent("Other.swift")
+      .appending(components: "Sources", "MyLibrary", "Other.swift")
     let newFileUri = DocumentURI(newFileUrl)
 
     let newFileContents = """
diff --git a/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift b/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
index 6b9fd2c61..2b1929cdc 100644
--- a/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
+++ b/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
@@ -59,7 +59,7 @@ class WorkspaceSymbolsTests: XCTestCase {
         """,
       ],
       workspaces: {
-        return [WorkspaceFolder(uri: DocumentURI($0.appendingPathComponent("packageB")))]
+        return [WorkspaceFolder(uri: DocumentURI($0.appending(component: "packageB")))]
       },
       enableBackgroundIndexing: true
     )
diff --git a/Tests/SourceKitLSPTests/WorkspaceTests.swift b/Tests/SourceKitLSPTests/WorkspaceTests.swift
index f054a48ad..1a813a5d5 100644
--- a/Tests/SourceKitLSPTests/WorkspaceTests.swift
+++ b/Tests/SourceKitLSPTests/WorkspaceTests.swift
@@ -77,8 +77,8 @@ final class WorkspaceTests: XCTestCase {
       ],
       workspaces: { scratchDir in
         return [
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageA"))),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageB"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageA"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageB"))),
         ]
       },
       enableBackgroundIndexing: true
@@ -174,14 +174,14 @@ final class WorkspaceTests: XCTestCase {
       workspaces: { scratchDir in
         return [
           WorkspaceFolder(uri: DocumentURI(scratchDir)),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageA"))),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageB"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageA"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageB"))),
         ]
       }
     )
 
     let bPackageManifestUri = DocumentURI(
-      project.scratchDirectory.appendingPathComponent("PackageB").appendingPathComponent("Package.swift")
+      project.scratchDirectory.appending(components: "PackageB", "Package.swift")
     )
 
     project.testClient.openDocument(SwiftPMTestProject.defaultPackageManifest, uri: bPackageManifestUri)
@@ -207,32 +207,30 @@ final class WorkspaceTests: XCTestCase {
       workspaces: { scratchDir in
         return [
           WorkspaceFolder(uri: DocumentURI(scratchDir)),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageA"))),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageB"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageA"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageB"))),
         ]
       }
     )
 
     let pkgA = DocumentURI(
       project.scratchDirectory
-        .appendingPathComponent("PackageA")
-        .appendingPathComponent("Package.swift")
+        .appending(components: "PackageA", "Package.swift")
     )
 
     let pkgB = DocumentURI(
       project.scratchDirectory
-        .appendingPathComponent("PackageB")
-        .appendingPathComponent("Package.swift")
+        .appending(components: "PackageB", "Package.swift")
     )
 
     assertEqual(
       await project.testClient.server.workspaceForDocument(uri: pkgA)?.rootUri,
-      DocumentURI(project.scratchDirectory.appendingPathComponent("PackageA"))
+      DocumentURI(project.scratchDirectory.appending(component: "PackageA"))
     )
 
     assertEqual(
       await project.testClient.server.workspaceForDocument(uri: pkgB)?.rootUri,
-      DocumentURI(project.scratchDirectory.appendingPathComponent("PackageB"))
+      DocumentURI(project.scratchDirectory.appending(component: "PackageB"))
     )
   }
 
@@ -467,8 +465,8 @@ final class WorkspaceTests: XCTestCase {
       ],
       workspaces: { scratchDir in
         return [
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("WorkspaceA"))),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("WorkspaceB"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "WorkspaceA"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "WorkspaceB"))),
         ]
       },
       usePullDiagnostics: false
@@ -516,8 +514,8 @@ final class WorkspaceTests: XCTestCase {
       ],
       workspaces: { scratchDir in
         return [
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageA"))),
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("PackageB"))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageA", directoryHint: .isDirectory))),
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "PackageB", directoryHint: .isDirectory))),
         ]
       }
     )
@@ -528,7 +526,7 @@ final class WorkspaceTests: XCTestCase {
     // yet) will belong to PackageA by default (because it provides fallback build settings for it).
     assertEqual(
       await project.testClient.server.workspaceForDocument(uri: mainUri)?.rootUri,
-      DocumentURI(project.scratchDirectory.appendingPathComponent("PackageA"))
+      DocumentURI(project.scratchDirectory.appending(component: "PackageA", directoryHint: .isDirectory))
     )
 
     // Add the MyExec target to PackageB/Package.swift
@@ -547,8 +545,7 @@ final class WorkspaceTests: XCTestCase {
       """
 
     let packageBManifestPath = project.scratchDirectory
-      .appendingPathComponent("PackageB")
-      .appendingPathComponent("Package.swift")
+      .appending(components: "PackageB", "Package.swift")
 
     try await newPackageManifest.writeWithRetry(to: packageBManifestPath)
     project.testClient.send(
@@ -563,7 +560,9 @@ final class WorkspaceTests: XCTestCase {
     // thus workspace membership should switch to PackageB.
 
     // Updating the build settings takes a few seconds. Send code completion requests every second until we receive correct results.
-    let packageBRootUri = DocumentURI(project.scratchDirectory.appendingPathComponent("PackageB"))
+    let packageBRootUri = DocumentURI(
+      project.scratchDirectory.appending(component: "PackageB", directoryHint: .isDirectory)
+    )
     try await repeatUntilExpectedResult {
       await project.testClient.server.workspaceForDocument(uri: mainUri)?.rootUri == packageBRootUri
     }
@@ -668,7 +667,7 @@ final class WorkspaceTests: XCTestCase {
       ],
       workspaces: { scratchDir in
         return [
-          WorkspaceFolder(uri: DocumentURI(scratchDir.appendingPathComponent("fake")))
+          WorkspaceFolder(uri: DocumentURI(scratchDir.appending(component: "fake")))
         ]
       }
     )
@@ -1304,7 +1303,7 @@ final class WorkspaceTests: XCTestCase {
 
     // Explicitly create a directory at /tmp (which is a standardized path but whose realpath is /private/tmp)
     let scratchDirectory = URL(fileURLWithPath: "/tmp")
-      .appendingPathComponent(testScratchName())
+      .appending(component: testScratchName())
     try FileManager.default.createDirectory(at: scratchDirectory, withIntermediateDirectories: true)
 
     defer {
@@ -1343,8 +1342,8 @@ final class WorkspaceTests: XCTestCase {
     let clangOutput = try await withTimeout(defaultTimeoutDuration) {
       try await Process.checkNonZeroExit(
         arguments: [
-          clang.filePath, "-index-store-path", scratchDirectory.appendingPathComponent("index").filePath,
-          scratchDirectory.appendingPathComponent("test.c").filePath,
+          clang.filePath, "-index-store-path", scratchDirectory.appending(component: "index").filePath,
+          scratchDirectory.appending(component: "test.c").filePath,
           "-fsyntax-only",
         ]
       )
@@ -1361,7 +1360,7 @@ final class WorkspaceTests: XCTestCase {
     // path as `/private/tmp` while the build server only knows about it as `/tmp`.
     let options = try await testClient.send(
       SourceKitOptionsRequest(
-        textDocument: TextDocumentIdentifier(scratchDirectory.appendingPathComponent("test.h")),
+        textDocument: TextDocumentIdentifier(scratchDirectory.appending(component: "test.h")),
         prepareTarget: false,
         allowFallbackSettings: false
       )
diff --git a/Tests/SwiftSourceKitPluginTests/PluginSwiftPMTestProject.swift b/Tests/SwiftSourceKitPluginTests/PluginSwiftPMTestProject.swift
index 2315fce0b..00a2d1712 100644
--- a/Tests/SwiftSourceKitPluginTests/PluginSwiftPMTestProject.swift
+++ b/Tests/SwiftSourceKitPluginTests/PluginSwiftPMTestProject.swift
@@ -36,7 +36,7 @@ final class PluginSwiftPMTestProject {
         buildServerSpec: BuildServerSpec(
           kind: .swiftPM,
           projectRoot: scratchDirectory,
-          configPath: scratchDirectory.appendingPathComponent("Package.swift")
+          configPath: scratchDirectory.appending(component: "Package.swift")
         ),
         toolchainRegistry: .forTesting,
         options: try .testDefault(backgroundIndexing: false),
diff --git a/Tests/TSCExtensionsTests/ProcessRunTests.swift b/Tests/TSCExtensionsTests/ProcessRunTests.swift
index 92bc4b004..48ffe622a 100644
--- a/Tests/TSCExtensionsTests/ProcessRunTests.swift
+++ b/Tests/TSCExtensionsTests/ProcessRunTests.swift
@@ -21,7 +21,7 @@ import class TSCBasic.Process
 final class ProcessRunTests: XCTestCase {
   func testWorkingDirectory() async throws {
     try await withTestScratchDir { tempDir in
-      let workingDir = tempDir.appendingPathComponent("working-dir")
+      let workingDir = tempDir.appending(component: "working-dir")
       try FileManager.default.createDirectory(at: workingDir, withIntermediateDirectories: true)
 
       #if os(Windows)
@@ -32,7 +32,7 @@ final class ProcessRunTests: XCTestCase {
       #endif
       let python = try await unwrap(findTool(name: pythonName))
 
-      let pythonFile = tempDir.appendingPathComponent("show-cwd.py")
+      let pythonFile = tempDir.appending(component: "show-cwd.py")
       try """
       import os
       print(os.getcwd(), end='')
diff --git a/Tests/ToolchainRegistryTests/ToolchainRegistryTests.swift b/Tests/ToolchainRegistryTests/ToolchainRegistryTests.swift
index 60c4bf10c..32d9b452a 100644
--- a/Tests/ToolchainRegistryTests/ToolchainRegistryTests.swift
+++ b/Tests/ToolchainRegistryTests/ToolchainRegistryTests.swift
@@ -46,13 +46,12 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+        .appending(components: "Xcode.app", "Developer")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
       try makeXCToolchain(
         identifier: ToolchainRegistry.darwinDefaultToolchainIdentifier,
         opensource: false,
-        path: toolchains.appendingPathComponent("XcodeDefault.xctoolchain"),
+        path: toolchains.appending(component: "XcodeDefault.xctoolchain"),
         sourcekitd: true
       )
 
@@ -69,7 +68,7 @@ final class ToolchainRegistryTests: XCTestCase {
       assertEqual(await tr.default?.identifier, ToolchainRegistry.darwinDefaultToolchainIdentifier)
       assertEqual(
         await tr.default?.path,
-        toolchains.appendingPathComponent("XcodeDefault.xctoolchain", isDirectory: true)
+        toolchains.appending(component: "XcodeDefault.xctoolchain", directoryHint: .isDirectory)
       )
       assertNotNil(await tr.default?.sourcekitd)
 
@@ -83,20 +82,19 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+        .appending(components: "Xcode.app", "Developer")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
 
       try makeXCToolchain(
         identifier: "com.apple.fake.A",
         opensource: false,
-        path: toolchains.appendingPathComponent("A.xctoolchain"),
+        path: toolchains.appending(component: "A.xctoolchain"),
         sourcekitd: true
       )
       try makeXCToolchain(
         identifier: "com.apple.fake.B",
         opensource: false,
-        path: toolchains.appendingPathComponent("B.xctoolchain"),
+        path: toolchains.appending(component: "B.xctoolchain"),
         sourcekitd: true
       )
 
@@ -119,20 +117,19 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+        .appending(components: "Xcode.app", "Developer")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
 
       try makeXCToolchain(
         identifier: "com.apple.fake.C",
         opensource: false,
-        path: toolchains.appendingPathComponent("C.wrong_extension"),
+        path: toolchains.appending(component: "C.wrong_extension"),
         sourcekitd: true
       )
       try makeXCToolchain(
         identifier: "com.apple.fake.D",
         opensource: false,
-        path: toolchains.appendingPathComponent("D_no_extension"),
+        path: toolchains.appending(component: "D_no_extension"),
         sourcekitd: true
       )
 
@@ -155,21 +152,20 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
+        .appending(components: "Xcode.app", "Developer")
 
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
       try makeXCToolchain(
         identifier: "com.apple.fake.A",
         opensource: false,
-        path: toolchains.appendingPathComponent("A.xctoolchain"),
+        path: toolchains.appending(component: "A.xctoolchain"),
         sourcekitd: true
       )
 
       try makeXCToolchain(
         identifier: "com.apple.fake.A",
         opensource: false,
-        path: toolchains.appendingPathComponent("E.xctoolchain"),
+        path: toolchains.appending(component: "E.xctoolchain"),
         sourcekitd: true
       )
 
@@ -189,15 +185,13 @@ final class ToolchainRegistryTests: XCTestCase {
   func testGloballyInstalledToolchains() async throws {
     try SkipUnless.platformIsDarwin("Finding toolchains in Xcode is only supported on macOS")
     try await withTestScratchDir { tempDir in
-      let libraryDir = tempDir.appendingPathComponent("Library")
+      let libraryDir = tempDir.appending(component: "Library")
       try makeXCToolchain(
         identifier: "org.fake.global.A",
         opensource: true,
         path:
           libraryDir
-          .appendingPathComponent("Developer")
-          .appendingPathComponent("Toolchains")
-          .appendingPathComponent("A.xctoolchain"),
+          .appending(components: "Developer", "Toolchains", "A.xctoolchain"),
         sourcekitd: true
       )
 
@@ -219,12 +213,11 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
+        .appending(components: "Xcode.app", "Developer")
 
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
 
-      let path = toolchains.appendingPathComponent("Explicit.xctoolchain", isDirectory: true)
+      let path = toolchains.appending(component: "Explicit.xctoolchain", directoryHint: .isDirectory)
       try makeXCToolchain(
         identifier: "org.fake.explicit",
         opensource: false,
@@ -233,7 +226,7 @@ final class ToolchainRegistryTests: XCTestCase {
       )
 
       let trInstall = ToolchainRegistry(
-        installPath: path.appendingPathComponent("usr").appendingPathComponent("bin"),
+        installPath: path.appending(components: "usr", "bin"),
         environmentVariables: [],
         xcodes: [],
         libraryDirectories: [],
@@ -251,21 +244,20 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
+        .appending(components: "Xcode.app", "Developer")
 
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
       try makeXCToolchain(
         identifier: ToolchainRegistry.darwinDefaultToolchainIdentifier,
         opensource: false,
-        path: toolchains.appendingPathComponent("XcodeDefault.xctoolchain"),
+        path: toolchains.appending(component: "XcodeDefault.xctoolchain"),
         sourcekitd: true
       )
 
       try makeXCToolchain(
         identifier: "org.fake.global.A",
         opensource: false,
-        path: toolchains.appendingPathComponent("A.xctoolchain"),
+        path: toolchains.appending(component: "A.xctoolchain"),
         sourcekitd: true
       )
 
@@ -299,11 +291,10 @@ final class ToolchainRegistryTests: XCTestCase {
     try await withTestScratchDir { tempDir in
       let xcodeDeveloper =
         tempDir
-        .appendingPathComponent("Xcode.app")
-        .appendingPathComponent("Developer")
-      let toolchains = xcodeDeveloper.appendingPathComponent("Toolchains")
+        .appending(components: "Xcode.app", "Developer")
+      let toolchains = xcodeDeveloper.appending(component: "Toolchains")
 
-      let path = toolchains.appendingPathComponent("Explicit.xctoolchain", isDirectory: true)
+      let path = toolchains.appending(component: "Explicit.xctoolchain", directoryHint: .isDirectory)
       try makeXCToolchain(
         identifier: "org.fake.explicit",
         opensource: false,
@@ -315,7 +306,7 @@ final class ToolchainRegistryTests: XCTestCase {
       XCTAssertNotNil(tc)
       XCTAssertEqual(tc?.identifier, "org.fake.explicit")
 
-      let tcBin = Toolchain(path.appendingPathComponent("usr").appendingPathComponent("bin"))
+      let tcBin = Toolchain(path.appending(components: "usr", "bin"))
       XCTAssertNotNil(tcBin)
       XCTAssertEqual(tc?.identifier, tcBin?.identifier)
       XCTAssertEqual(tc?.path, tcBin?.path)
@@ -378,7 +369,7 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testSearchExplicitEnvBuiltin() async throws {
     try await withTestScratchDir { tempDir in
-      let binPath = tempDir.appendingPathComponent("bin", isDirectory: true)
+      let binPath = tempDir.appending(component: "bin", directoryHint: .isDirectory)
       try makeToolchain(binPath: binPath, sourcekitd: true)
 
       try ProcessEnv.setVar("TEST_SOURCEKIT_TOOLCHAIN_PATH_1", value: binPath.deletingLastPathComponent().filePath)
@@ -409,7 +400,7 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testSearchExplicitEnv() async throws {
     try await withTestScratchDir { tempDir in
-      let binPath = tempDir.appendingPathComponent("bin", isDirectory: true)
+      let binPath = tempDir.appending(component: "bin", directoryHint: .isDirectory)
       try makeToolchain(binPath: binPath, sourcekitd: true)
 
       try ProcessEnv.setVar("TEST_ENV_SOURCEKIT_TOOLCHAIN_PATH_2", value: binPath.deletingLastPathComponent().filePath)
@@ -439,9 +430,9 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testFromDirectory() async throws {
     try await withTestScratchDir { tempDir in
-      let path = tempDir.appendingPathComponent("A.xctoolchain").appendingPathComponent("usr")
+      let path = tempDir.appending(components: "A.xctoolchain", "usr")
       try makeToolchain(
-        binPath: path.appendingPathComponent("bin"),
+        binPath: path.appending(component: "bin"),
         clang: true,
         clangd: true,
         swiftc: true,
@@ -449,7 +440,7 @@ final class ToolchainRegistryTests: XCTestCase {
         sourcekitd: true
       )
 
-      try Data().write(to: path.appendingPathComponent("bin").appendingPathComponent("other"))
+      try Data().write(to: path.appending(components: "bin", "other"))
 
       let t1 = try XCTUnwrap(Toolchain(path.deletingLastPathComponent()))
       XCTAssertNotNil(t1.sourcekitd)
@@ -470,10 +461,10 @@ final class ToolchainRegistryTests: XCTestCase {
         XCTAssertEqual(chmod(try path.filePath, S_IRUSR | S_IXUSR), 0)
       }
 
-      try chmodRX(path.appendingPathComponent("bin").appendingPathComponent("clang"))
-      try chmodRX(path.appendingPathComponent("bin").appendingPathComponent("clangd"))
-      try chmodRX(path.appendingPathComponent("bin").appendingPathComponent("swiftc"))
-      try chmodRX(path.appendingPathComponent("bin").appendingPathComponent("other"))
+      try chmodRX(path.appending(components: "bin", "clang"))
+      try chmodRX(path.appending(components: "bin", "clangd"))
+      try chmodRX(path.appending(components: "bin", "swiftc"))
+      try chmodRX(path.appending(components: "bin", "other"))
       #endif
 
       let t2 = try XCTUnwrap(Toolchain(path.deletingLastPathComponent()))
@@ -493,7 +484,7 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testDylibNames() async throws {
     try await withTestScratchDir { tempDir in
-      let binPath = tempDir.appendingPathComponent("bin", isDirectory: true)
+      let binPath = tempDir.appending(component: "bin", directoryHint: .isDirectory)
       try makeToolchain(binPath: binPath, sourcekitdInProc: true, libIndexStore: true)
       guard let t = Toolchain(binPath) else {
         XCTFail("could not find any tools")
@@ -506,30 +497,28 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testSubDirs() async throws {
     try await withTestScratchDir { tempDir in
-      try makeToolchain(binPath: tempDir.appendingPathComponent("t1").appendingPathComponent("bin"), sourcekitd: true)
+      try makeToolchain(binPath: tempDir.appending(components: "t1", "bin"), sourcekitd: true)
       try makeToolchain(
-        binPath: tempDir.appendingPathComponent("t2").appendingPathComponent("usr").appendingPathComponent("bin"),
+        binPath: tempDir.appending(components: "t2", "usr", "bin"),
         sourcekitd: true
       )
 
-      XCTAssertNotNil(Toolchain(tempDir.appendingPathComponent("t1")))
-      XCTAssertNotNil(Toolchain(tempDir.appendingPathComponent("t1").appendingPathComponent("bin")))
-      XCTAssertNotNil(Toolchain(tempDir.appendingPathComponent("t2")))
+      XCTAssertNotNil(Toolchain(tempDir.appending(component: "t1")))
+      XCTAssertNotNil(Toolchain(tempDir.appending(components: "t1", "bin")))
+      XCTAssertNotNil(Toolchain(tempDir.appending(component: "t2")))
 
-      XCTAssertNil(Toolchain(tempDir.appendingPathComponent("t3")))
+      XCTAssertNil(Toolchain(tempDir.appending(component: "t3")))
       try FileManager.default.createDirectory(
-        at: tempDir.appendingPathComponent("t3").appendingPathComponent("bin"),
+        at: tempDir.appending(components: "t3", "bin"),
         withIntermediateDirectories: true
       )
       try FileManager.default.createDirectory(
-        at: tempDir.appendingPathComponent("t3").appendingPathComponent("lib").appendingPathComponent(
-          "sourcekitd.framework"
-        ),
+        at: tempDir.appending(components: "t3", "lib", "sourcekitd.framework"),
         withIntermediateDirectories: true
       )
-      XCTAssertNil(Toolchain(tempDir.appendingPathComponent("t3")))
-      try makeToolchain(binPath: tempDir.appendingPathComponent("t3").appendingPathComponent("bin"), sourcekitd: true)
-      XCTAssertNotNil(Toolchain(tempDir.appendingPathComponent("t3")))
+      XCTAssertNil(Toolchain(tempDir.appending(component: "t3")))
+      try makeToolchain(binPath: tempDir.appending(components: "t3", "bin"), sourcekitd: true)
+      XCTAssertNotNil(Toolchain(tempDir.appending(component: "t3")))
     }
   }
 
@@ -576,7 +565,7 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testInstallPath() async throws {
     try await withTestScratchDir { tempDir in
-      let binPath = tempDir.appendingPathComponent("t1").appendingPathComponent("bin", isDirectory: true)
+      let binPath = tempDir.appending(components: "t1", "bin", directoryHint: .isDirectory)
       try makeToolchain(binPath: binPath, sourcekitd: true)
 
       let trEmpty = ToolchainRegistry(
@@ -601,7 +590,7 @@ final class ToolchainRegistryTests: XCTestCase {
       await assertNotNil(tr1.default?.sourcekitd)
 
       let tr2 = ToolchainRegistry(
-        installPath: tempDir.appendingPathComponent("t2").appendingPathComponent("bin", isDirectory: true),
+        installPath: tempDir.appending(components: "t2", "bin", directoryHint: .isDirectory),
         environmentVariables: [],
         xcodes: [],
         libraryDirectories: [],
@@ -614,8 +603,8 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testInstallPathVsEnv() async throws {
     try await withTestScratchDir { tempDir in
-      let t1Bin = tempDir.appendingPathComponent("t1").appendingPathComponent("bin", isDirectory: true)
-      let t2Bin = tempDir.appendingPathComponent("t2").appendingPathComponent("bin", isDirectory: true)
+      let t1Bin = tempDir.appending(components: "t1", "bin", directoryHint: .isDirectory)
+      let t2Bin = tempDir.appending(components: "t2", "bin", directoryHint: .isDirectory)
       try makeToolchain(binPath: t1Bin, sourcekitd: true)
       try makeToolchain(binPath: t2Bin, sourcekitd: true)
 
@@ -638,22 +627,21 @@ final class ToolchainRegistryTests: XCTestCase {
 
   func testSupersetToolchains() async throws {
     try await withTestScratchDir { tempDir in
-      let usrLocal = tempDir.appendingPathComponent("usr").appendingPathComponent("local")
-      let usr = tempDir.appendingPathComponent("usr")
+      let usrLocal = tempDir.appending(components: "usr", "local")
+      let usr = tempDir.appending(component: "usr")
 
       let onlySwiftcToolchain = Toolchain(
         identifier: "onlySwiftc",
         displayName: "onlySwiftc",
         path: usrLocal,
-        swiftc: usrLocal.appendingPathComponent("bin").appendingPathComponent("swiftc")
+        swiftc: usrLocal.appending(components: "bin", "swiftc")
       )
       let swiftcAndSourcekitdToolchain = Toolchain(
         identifier: "swiftcAndSourcekitd",
         displayName: "swiftcAndSourcekitd",
         path: usr,
-        swiftc: usr.appendingPathComponent("bin").appendingPathComponent("swiftc"),
-        sourcekitd: usrLocal.appendingPathComponent("lib").appendingPathComponent("sourcekitd.framework")
-          .appendingPathComponent("sourcekitd")
+        swiftc: usr.appending(components: "bin", "swiftc"),
+        sourcekitd: usrLocal.appending(components: "lib", "sourcekitd.framework", "sourcekitd")
       )
 
       let tr = ToolchainRegistry(toolchains: [onlySwiftcToolchain, swiftcAndSourcekitdToolchain])
@@ -675,14 +663,14 @@ private func makeXCToolchain(
   libIndexStore: Bool = false
 ) throws {
   try FileManager.default.createDirectory(at: path, withIntermediateDirectories: true)
-  let infoPlistPath = path.appendingPathComponent(opensource ? "Info.plist" : "ToolchainInfo.plist")
+  let infoPlistPath = path.appending(component: opensource ? "Info.plist" : "ToolchainInfo.plist")
   let infoPlist = try PropertyListEncoder().encode(
     XCToolchainPlist(identifier: identifier, displayName: "name-\(identifier)")
   )
   try infoPlist.write(to: infoPlistPath)
 
   try makeToolchain(
-    binPath: path.appendingPathComponent("usr").appendingPathComponent("bin"),
+    binPath: path.appending(components: "usr", "bin"),
     clang: clang,
     clangd: clangd,
     swiftc: swiftc,
@@ -716,7 +704,7 @@ private func makeToolchain(
     0x02,
   ]
 
-  let libPath = binPath.deletingLastPathComponent().appendingPathComponent("lib")
+  let libPath = binPath.deletingLastPathComponent().appending(component: "lib")
   try FileManager.default.createDirectory(at: binPath, withIntermediateDirectories: true)
   try FileManager.default.createDirectory(at: libPath, withIntermediateDirectories: true)
 
@@ -732,37 +720,37 @@ private func makeToolchain(
   let execExt = Platform.current?.executableExtension ?? ""
 
   if clang {
-    try makeExec(binPath.appendingPathComponent("clang\(execExt)"))
+    try makeExec(binPath.appending(component: "clang\(execExt)"))
   }
   if clangd {
-    try makeExec(binPath.appendingPathComponent("clangd\(execExt)"))
+    try makeExec(binPath.appending(component: "clangd\(execExt)"))
   }
   if swiftc {
-    try makeExec(binPath.appendingPathComponent("swiftc\(execExt)"))
+    try makeExec(binPath.appending(component: "swiftc\(execExt)"))
   }
 
   let dylibSuffix = Platform.current?.dynamicLibraryExtension ?? ".so"
 
   if sourcekitd {
     try FileManager.default.createDirectory(
-      at: libPath.appendingPathComponent("sourcekitd.framework"),
+      at: libPath.appending(component: "sourcekitd.framework"),
       withIntermediateDirectories: true
     )
-    try Data().write(to: libPath.appendingPathComponent("sourcekitd.framework").appendingPathComponent("sourcekitd"))
+    try Data().write(to: libPath.appending(components: "sourcekitd.framework", "sourcekitd"))
   }
   if sourcekitdInProc {
     #if os(Windows)
-    try Data().write(to: binPath.appendingPathComponent("sourcekitdInProc\(dylibSuffix)"))
+    try Data().write(to: binPath.appending(component: "sourcekitdInProc\(dylibSuffix)"))
     #else
-    try Data().write(to: libPath.appendingPathComponent("libsourcekitdInProc\(dylibSuffix)"))
+    try Data().write(to: libPath.appending(component: "libsourcekitdInProc\(dylibSuffix)"))
     #endif
   }
   if libIndexStore {
     #if os(Windows)
     // Windows has a prefix of `lib` on this particular library ...
-    try Data().write(to: binPath.appendingPathComponent("libIndexStore\(dylibSuffix)"))
+    try Data().write(to: binPath.appending(component: "libIndexStore\(dylibSuffix)"))
     #else
-    try Data().write(to: libPath.appendingPathComponent("libIndexStore\(dylibSuffix)"))
+    try Data().write(to: libPath.appending(component: "libIndexStore\(dylibSuffix)"))
     #endif
   }
 }