swiftlang · rintaro · May 28, 2026 · May 23, 2026 · May 27, 2026
@@ -181,9 +181,10 @@ private enum BuildServerAdapter {
           if Task.isCancelled {
             return continuation.resume(throwing: CancellationError())
           }
-          requestID.value = messageHandler.send(request) { response in
+          let id = messageHandler.send(request) { response in
             continuation.resume(with: response)
           }
+          requestID.withLock { $0 = id }
           if Task.isCancelled {
             // The task might have been cancelled after we checked `Task.isCancelled` above but before `requestID.value`
             // is set, we won't send a `CancelRequestNotification` from the `onCancel` handler. Send it from here.

@@ -261,7 +261,7 @@ package struct DiagnoseCommand: AsyncParsableCommand {
     )
     try process.launch()
     try await process.waitUntilExit()
-    processExited.value = true
+    processExited.withLock { $0 = true }
     #endif
   }
 

@@ -18,6 +18,7 @@ import IndexStoreDB
 import SemanticIndex
 @_spi(Linkcompletion) @preconcurrency import SwiftDocC
 import SwiftExtensions
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 
 final class DocCReferenceResolutionService: DocumentationService, Sendable {
   /// The message type that this service accepts.
@@ -33,11 +34,11 @@ final class DocCReferenceResolutionService: DocumentationService, Sendable {
   init() {}
 
   func addContext(_ context: DocCReferenceResolutionContext, withKey key: String) {
-    contextMap.value[key] = context
+    contextMap.withLock { $0[key] = context }
   }
 
   @discardableResult func removeContext(forKey key: String) -> DocCReferenceResolutionContext? {
-    contextMap.value.removeValue(forKey: key)
+    contextMap.withLock { $0.removeValue(forKey: key) }
   }
 
   func context(forKey key: String) -> DocCReferenceResolutionContext? {

@@ -100,9 +100,10 @@ public final class InProcessSourceKitLSPClient: Sendable {
           // possible.
           return continuation.resume(throwing: CancellationError())
         }
-        requestId.value = self.send(request) {
+        let id = self.send(request) {
           continuation.resume(with: $0)
         }
+        requestId.withLock { $0 = id }
         if Task.isCancelled, let requestId = requestId.takeValue() {
           // The task might have been cancelled after the above cancellation check but before `requestId` was assigned
           // a value. To cover that case, check for cancellation here again. Note that we won't cancel twice from here

@@ -290,7 +290,7 @@ package final class CustomBuildServerTestProject<BuildServer: CustomBuildServer>
     XCTAssertNil(hooks.buildServerHooks.injectBuildServer)
     hooks.buildServerHooks.injectBuildServer = { [buildServerBox] projectRoot, connectionToSourceKitLSP in
       let buildServer = BuildServer(projectRoot: projectRoot, connectionToSourceKitLSP: connectionToSourceKitLSP)
-      buildServerBox.value = buildServer
+      buildServerBox.withLock { $0 = buildServer }
       return LocalConnection(receiverName: "TestBuildServer", handler: buildServer)
     }
     try await super.init(

@@ -70,12 +70,12 @@ final class PendingNotifications: Sendable {
   private let values = ThreadSafeBox<[any NotificationType]>(initialValue: [])
 
   nonisolated func add(_ value: any NotificationType) {
-    values.value.insert(value, at: 0)
+    values.withLock { $0.insert(value, at: 0) }
   }
 
   func next(timeout: Duration, pollingInterval: Duration = .milliseconds(10)) async throws -> any NotificationType {
     for _ in 0..<Int(timeout.seconds / pollingInterval.seconds) {
-      if let value = values.value.popLast() {
+      if let value = values.withLock({ $0.popLast() }) {
         return value
       }
       try await Task.sleep(for: pollingInterval)
@@ -387,12 +387,12 @@ package final class TestSourceKitLSPClient: MessageHandler, Sendable {
   /// The request handler will only handle a single request. If the request is called again, the request handler won't
   /// call again
   package func handleSingleRequest<R: RequestType>(_ requestHandler: @escaping RequestHandler<R>) {
-    requestHandlers.value.append((requestHandler: requestHandler, isOneShot: true))
+    requestHandlers.withLock { $0.append((requestHandler: requestHandler, isOneShot: true)) }
   }
 
   /// Handle all requests of the given type that are sent to the client.
   package func handleMultipleRequests<R: RequestType>(_ requestHandler: @escaping RequestHandler<R>) {
-    requestHandlers.value.append((requestHandler: requestHandler, isOneShot: false))
+    requestHandlers.withLock { $0.append((requestHandler: requestHandler, isOneShot: false)) }
   }
 
   /// Executes `operation` and waits until a request of the specified type is received from the server.
@@ -407,7 +407,7 @@ package final class TestSourceKitLSPClient: MessageHandler, Sendable {
     // Register a one-shot handler that records when the request arrives.
     let received = ThreadSafeBox<Bool>(initialValue: false)
     self.handleSingleRequest { (_: R) in
-      received.value = true
+      received.withLock { $0 = true }
       return VoidResponse()
     }
 

@@ -16,6 +16,7 @@ package import Foundation
 @_spi(SourceKitLSP) package import LanguageServerProtocol
 @_spi(SourceKitLSP) import SKLogging
 import SwiftExtensions
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 
 /// Essentially a `DocumentManager` from the `SourceKitLSP` module.
 ///
@@ -355,7 +356,7 @@ package final actor UncheckedIndex: Sendable {
   package func close() {
     // IndexStoreDB writes the index to disk when the retain count of the `IndexStoreDB` object hits zero. We hope that
     // nobody else still has a reference to `IndexStoreDB` here.
-    _underlyingIndexStoreDB.value = nil
+    _underlyingIndexStoreDB.withLock { $0 = nil }
   }
 
   /// Update the set of output paths that should be considered visible in the project. For example, if a source file is

@@ -23,7 +23,7 @@ extension sourcekitd_api_values: @unchecked Sendable {}
 fileprivate extension ThreadSafeBox {
   /// If the wrapped value is `nil`, run `compute` and store the computed value. If it is not `nil`, return the stored
   /// value.
-  func computeIfNil<WrappedValue: Sendable>(compute: () -> WrappedValue) -> WrappedValue where T == WrappedValue? {
+  func computeIfNil<WrappedValue: Sendable>(compute: () -> WrappedValue) -> WrappedValue where Value == WrappedValue? {
     return withLock { (value: inout WrappedValue?) -> WrappedValue in
       if let value {
         return value

@@ -12,6 +12,7 @@
 
 @_spi(SourceKitLSP) import SKLogging
 import SwiftExtensions
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 
 #if os(Windows)
 import CRT
@@ -79,7 +80,7 @@ package final class DLHandle: Sendable {
 
   /// The handle must not be used anymore after calling `leak`.
   package func leak() {
-    rawValue.value = nil
+    rawValue.withLock { $0 = nil }
   }
 }
 

@@ -17,6 +17,7 @@ package import SKUtilities
 import SemanticIndex
 import SwiftExtensions
 package import SwiftSyntax
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 
 /// An immutable snapshot of a document at a given time.
 ///

@@ -99,7 +99,7 @@ package func withTimeoutResult<T: Sendable>(
   let stream = AsyncThrowingStream<WithTimeoutResult<T>, any Error> { continuation in
     Task {
       try await Task.sleep(for: timeout)
-      didHitTimeout.value = true
+      didHitTimeout.withLock { $0 = true }
       continuation.yield(.timedOut)
     }
 

@@ -11,15 +11,13 @@ set(sources
   Duration+Seconds.swift
   FileManagerExtensions.swift
   LazyValue.swift
-  NSLock+WithLock.swift
   PipeAsStringHandler.swift
   Platform.swift
   Process+terminate.swift
   ResultExtensions.swift
   RunWithCleanup.swift
   Sequence+AsyncMap.swift
   Sequence+ContainsAnyIn.swift
-  ThreadSafeBox.swift
   TransitiveClosure.swift
   URLExtensions.swift
 )

@@ -35,7 +35,7 @@ extension Process {
     let hasExited = ThreadSafeBox<Bool>(initialValue: false)
     return try await withTaskCancellationHandler {
       defer {
-        hasExited.value = true
+        hasExited.withLock { $0 = true }
       }
       return try await waitUntilExit()
     } onCancel: {

@@ -15,6 +15,7 @@ import RegexBuilder
 @_spi(SourceKitLSP) import SKLogging
 import SwiftExtensions
 import TSCExtensions
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 
 import class TSCBasic.Process
 

@@ -21,6 +21,7 @@ import SKTestSupport
 import SwiftExtensions
 import TSCBasic
 import ToolchainRegistry
+@_spi(SourceKitLSP) import ToolsProtocolsSwiftExtensions
 import XCTest
 
 fileprivate actor TestBuildServer: CustomBuildServer {
@@ -63,7 +64,7 @@ private func createBuildServerManager(
     kind: .injected({ projectRoot, connectionToSourceKitLSP in
       assert(testBuildServer.value == nil, "Build server injector hook can only create a single TestBuildServer")
       let buildServer = TestBuildServer(projectRoot: projectRoot, connectionToSourceKitLSP: connectionToSourceKitLSP)
-      testBuildServer.value = buildServer
+      testBuildServer.withLock { $0 = buildServer }
       return LocalConnection(receiverName: "TestBuildServer", handler: buildServer)
     }),
     projectRoot: dummyPath,

@@ -1334,11 +1334,11 @@ struct SwiftPMBuildServerTests {
         in: tempDir,
         reloadPackageDidStart: {
           if packageInitialized.value {
-            unexpectedReloadStarted.value = true
+            unexpectedReloadStarted.withLock { $0 = true }
           }
         }
       )
-      packageInitialized.value = true
+      packageInitialized.withLock { $0 = true }
 
       // SwiftPM extracts the artifact bundle to:
       //   <scratch>/artifacts/<package-identity>/<target-name>/<artifact-name>/
@@ -1388,11 +1388,11 @@ struct SwiftPMBuildServerTests {
         options: SourceKitLSPOptions(swiftPM: .init(scratchPath: try customScratch.filePath)),
         reloadPackageDidStart: {
           if packageInitialized.value {
-            unexpectedReloadStarted.value = true
+            unexpectedReloadStarted.withLock { $0 = true }
           }
         }
       )
-      packageInitialized.value = true
+      packageInitialized.withLock { $0 = true }
 
       // With a custom scratch path, SwiftPM extracts to <custom-scratch>/artifacts/.
       // Simulate the delete-and-re-expand cycle for those paths.

@@ -261,7 +261,7 @@ final class TaskSchedulerTests: SourceKitLSPTestCase {
         return
       }
 
-      taskExecutedBefore.value = true
+      taskExecutedBefore.withLock { $0 = true }
 
       taskStartedExecuting.fulfill()
 

@@ -1392,7 +1392,7 @@ final class BackgroundIndexingTests: SourceKitLSPTestCase {
       hooks: testHooks,
       enableBackgroundIndexing: true
     )
-    packageInitialized.value = true
+    packageInitialized.withLock { $0 = true }
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [
         FileEvent(uri: DocumentURI(project.scratchDirectory.appending(component: "random.swift")), type: .created)
@@ -2186,7 +2186,7 @@ final class BackgroundIndexingTests: SourceKitLSPTestCase {
         return data.title == "Indexing"
       }
     )
-    receivedReportProgressNotification.value = true
+    receivedReportProgressNotification.withLock { $0 = true }
 
     // Check that we receive an `end` notification
     _ = try await project.testClient.nextNotification(
@@ -2255,7 +2255,7 @@ final class BackgroundIndexingTests: SourceKitLSPTestCase {
 
     // Ensure that changing `/private/tmp/.../test.c` only causes `/tmp/.../test.c` to be indexed, not
     // `/private/tmp/.../test.c`.
-    indexedFiles.value = []
+    indexedFiles.withLock { $0 = [] }
     let testFileURL = try XCTUnwrap(project.uri(for: "test.c").fileURL?.realpath)
     try await "void y() {}".writeWithRetry(to: testFileURL)
     project.testClient.send(
@@ -2603,7 +2603,7 @@ final class BackgroundIndexingTests: SourceKitLSPTestCase {
     let symbolsBeforeUpdate = try await project.testClient.send(WorkspaceSymbolsRequest(query: "myTestFu"))
     XCTAssertEqual(symbolsBeforeUpdate, [])
 
-    testSetupComplete.value = true
+    testSetupComplete.withLock { $0 = true }
     try await project.changeFileOnDisk(
       "Test.swift",
       newMarkedContents: """
@@ -2627,8 +2627,11 @@ final class BackgroundIndexingTests: SourceKitLSPTestCase {
     let testHooks = Hooks(
       buildServerHooks: BuildServerHooks(preHandleRequest: { request in
         if let request = request as? BuildTargetPrepareRequest {
-          preparationRequests.value.append(request)
-          if preparationRequests.value.count >= 2 {
+          let count = preparationRequests.withLock { (value: inout [BuildTargetPrepareRequest]) in
+            value.append(request)
+            return value.count
+          }
+          if count >= 2 {
             twoPreparationRequestsReceived.fulfill()
           }
         }

@@ -162,7 +162,7 @@ final class ClangdTests: SourceKitLSPTestCase {
     let clangdServer = try await unwrap(testClient.primaryLanguageService(for: uri))
     await clangdServer.addStateChangeHandler { oldState, newState in
       if oldState == .connectionInterrupted, newState == .connected {
-        clangdRestarted.value = true
+        clangdRestarted.withLock { $0 = true }
         clangdRestartedExpectation.fulfill()
       }
     }
-Original file line number
+Diff line change
@@ Expand Up / @@ -261,7 +261,7 @@ final class TaskSchedulerTests: SourceKitLSPTestCase { @@
             return
           }
-          taskExecutedBefore.value = true
+          taskExecutedBefore.withLock { $0 = true }
           taskStartedExecuting.fulfill()
@@ Expand Down @@