From dffcc939f7f0d9bde3915a5d19fa580a9670a3bd Mon Sep 17 00:00:00 2001
From: Alex Hoppen <ahoppen@apple.com>
Date: Fri, 29 Sep 2023 21:59:59 -0700
Subject: [PATCH] Change the build system to only notify delegate about changed
 files, not about new build settings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This defines away an entire class of data races if delegate callbacks are delivered out-of-order. If we aren’t providing the new build settings in the delegate callback, then it doesn’t matter if two `fileBuildSettingsChanged` calls change order since they don’t carry any state.
---
 Sources/SKCore/BuildServerBuildSystem.swift   |  6 +--
 Sources/SKCore/BuildSystemDelegate.swift      |  6 +--
 Sources/SKCore/BuildSystemManager.swift       | 46 +++++++++----------
 .../CompilationDatabaseBuildSystem.swift      | 11 ++---
 Sources/SKCore/FallbackBuildSystem.swift      |  3 +-
 .../SKSwiftPMWorkspace/SwiftPMWorkspace.swift | 17 +------
 .../Clang/ClangLanguageServer.swift           |  4 +-
 Sources/SourceKitLSP/SourceKitServer.swift    | 12 ++---
 .../Swift/SwiftLanguageServer.swift           |  2 +-
 .../ToolchainLanguageServer.swift             |  2 +-
 .../BuildServerBuildSystemTests.swift         |  5 +-
 .../SKCoreTests/BuildSystemManagerTests.swift | 34 +++++---------
 .../SourceKitLSPTests/BuildSystemTests.swift  | 15 +++---
 13 files changed, 59 insertions(+), 104 deletions(-)

diff --git a/Sources/SKCore/BuildServerBuildSystem.swift b/Sources/SKCore/BuildServerBuildSystem.swift
index 4f7e3a66..68659401 100644
--- a/Sources/SKCore/BuildServerBuildSystem.swift
+++ b/Sources/SKCore/BuildServerBuildSystem.swift
@@ -202,11 +202,7 @@ public actor BuildServerBuildSystem: MessageHandler {
   /// about the changed build settings.
   private func buildSettingsChanged(for document: DocumentURI, settings: FileBuildSettings?) async {
     buildSettings[document] = settings
-    if let settings {
-      await self.delegate?.fileBuildSettingsChanged([document: .modified(settings)])
-    } else {
-      await self.delegate?.fileBuildSettingsChanged([document: .removedOrUnavailable])
-    }
+    await self.delegate?.fileBuildSettingsChanged([document])
   }
 }
 
diff --git a/Sources/SKCore/BuildSystemDelegate.swift b/Sources/SKCore/BuildSystemDelegate.swift
index 948a861a..2e13029a 100644
--- a/Sources/SKCore/BuildSystemDelegate.swift
+++ b/Sources/SKCore/BuildSystemDelegate.swift
@@ -21,11 +21,7 @@ public protocol BuildSystemDelegate: AnyObject {
   func buildTargetsChanged(_ changes: [BuildTargetEvent]) async
 
   /// Notify the delegate that the given files' build settings have changed.
-  ///
-  /// The delegate should cache the new build settings for any of the given
-  /// files that they are interested in.
-  func fileBuildSettingsChanged(
-    _ changedFiles: [DocumentURI: FileBuildSettingsChange]) async
+  func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) async
 
   /// Notify the delegate that the dependencies of the given files have changed
   /// and that ASTs may need to be refreshed. If the given set is empty, assume
diff --git a/Sources/SKCore/BuildSystemManager.swift b/Sources/SKCore/BuildSystemManager.swift
index 596cdb4e..1bfe4cef 100644
--- a/Sources/SKCore/BuildSystemManager.swift
+++ b/Sources/SKCore/BuildSystemManager.swift
@@ -210,10 +210,8 @@ extension BuildSystemManager {
 
     let newStatus = await self.cachedStatusOrRegisterForSettings(for: mainFile, language: language)
 
-    if let mainChange = newStatus.buildSettingsChange,
-       let delegate = self._delegate {
-      let change = self.convert(change: mainChange, ofMainFile: mainFile, to: uri)
-      await delegate.fileBuildSettingsChanged([uri: change])
+    if newStatus.buildSettingsChange != nil, let delegate = self._delegate {
+      await delegate.fileBuildSettingsChanged([uri])
     }
   }
 
@@ -294,7 +292,7 @@ extension BuildSystemManager {
   /// Update and notify our delegate for the given main file changes if they are
   /// convertible into `FileBuildSettingsChange`.
   func updateAndNotifyStatuses(changes: [DocumentURI: MainFileStatus]) async {
-    var changedWatchedFiles = [DocumentURI: FileBuildSettingsChange]()
+    var changedWatchedFiles = Set<DocumentURI>()
     for (mainFile, status) in changes {
       let watches = self.watchedFiles.filter { $1.mainFile == mainFile }
       guard !watches.isEmpty else {
@@ -310,12 +308,11 @@ extension BuildSystemManager {
       guard prevStatus == .waiting || status.buildSettings != prevStatus?.buildSettings else {
         continue
       }
-      if let change = status.buildSettingsChange {
-        for watch in watches {
-          let newChange =
-            self.convert(change: change, ofMainFile: mainFile, to: watch.key)
-          changedWatchedFiles[watch.key] = newChange
-        }
+      guard status.buildSettingsChange != nil else {
+        continue
+      }
+      for watch in watches {
+        changedWatchedFiles.insert(watch.key)
       }
     }
 
@@ -374,26 +371,26 @@ extension BuildSystemManager {
 
 extension BuildSystemManager: BuildSystemDelegate {
   // FIXME: (async) Make this method isolated once `BuildSystemDelegate` has ben asyncified
-  public nonisolated func fileBuildSettingsChanged(_ changes: [DocumentURI: FileBuildSettingsChange]) {
+  public nonisolated func fileBuildSettingsChanged(_ changes: Set<DocumentURI>) {
     Task {
       await fileBuildSettingsChangedImpl(changes)
     }
   }
 
-  public func fileBuildSettingsChangedImpl(_ changes: [DocumentURI: FileBuildSettingsChange]) async {
-    let statusChanges: [DocumentURI: MainFileStatus] =
-        changes.reduce(into: [:]) { (result, entry) in
-      let mainFile = entry.key
-      let settingsChange = entry.value
+  public func fileBuildSettingsChangedImpl(_ changes: Set<DocumentURI>) async {
+    var statusChanges: [DocumentURI: MainFileStatus] = [:]
+    for mainFile in changes {
       let watches = self.watchedFiles.filter { $1.mainFile == mainFile }
       guard let firstWatch = watches.first else {
         // Possible notification after the file was unregistered. Ignore.
-        return
+        continue
       }
       let newStatus: MainFileStatus
 
-      if let newSettings = settingsChange.newSettings {
-        newStatus = settingsChange.isFallback ? .fallback(newSettings) : .primary(newSettings)
+      let settings = await self.buildSettings(for: mainFile, language: firstWatch.value.language)
+
+      if let settings {
+        newStatus = settings.isFallback ? .fallback(settings.buildSettings) : .primary(settings.buildSettings)
       } else if let fallback = self.fallbackBuildSystem {
         // FIXME: we need to stop threading the language everywhere, or we need the build system
         // itself to pass it in here. Or alternatively cache the fallback settings/language earlier?
@@ -406,7 +403,7 @@ extension BuildSystemManager: BuildSystemDelegate {
       } else {
         newStatus = .unsupported
       }
-      result[mainFile] = newStatus
+      statusChanges[mainFile] = newStatus
     }
     await self.updateAndNotifyStatuses(changes: statusChanges)
   }
@@ -474,7 +471,7 @@ extension BuildSystemManager: MainFilesDelegate {
   public func mainFilesChangedImpl() async {
     let origWatched = self.watchedFiles
     self.watchedFiles = [:]
-    var buildSettingsChanges = [DocumentURI: FileBuildSettingsChange]()
+    var buildSettingsChanges = Set<DocumentURI>()
 
     for (uri, state) in origWatched {
       let mainFiles = self._mainFilesProvider?.mainFilesContainingFile(uri) ?? []
@@ -489,9 +486,8 @@ extension BuildSystemManager: MainFilesDelegate {
 
         let newStatus = await self.cachedStatusOrRegisterForSettings(
             for: newMainFile, language: language)
-        if let change = newStatus.buildSettingsChange {
-          let newChange = self.convert(change: change, ofMainFile: newMainFile, to: uri)
-          buildSettingsChanges[uri] = newChange
+        if newStatus.buildSettingsChange != nil {
+          buildSettingsChanges.insert(uri)
         }
       }
     }
diff --git a/Sources/SKCore/CompilationDatabaseBuildSystem.swift b/Sources/SKCore/CompilationDatabaseBuildSystem.swift
index 3425d474..d64f6750 100644
--- a/Sources/SKCore/CompilationDatabaseBuildSystem.swift
+++ b/Sources/SKCore/CompilationDatabaseBuildSystem.swift
@@ -96,8 +96,7 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
 
     guard let delegate = self.delegate else { return }
 
-    let settings = self.settings(for: uri)
-    await delegate.fileBuildSettingsChanged([uri: FileBuildSettingsChange(settings)])
+    await delegate.fileBuildSettingsChanged([uri])
   }
 
   /// We don't support change watching.
@@ -148,13 +147,9 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
     self.compdb = tryLoadCompilationDatabase(directory: projectRoot, self.fileSystem)
 
     if let delegate = self.delegate {
-      var changedFiles: [DocumentURI: FileBuildSettingsChange] = [:]
+      var changedFiles = Set<DocumentURI>()
       for (uri, _) in self.watchedFiles {
-        if let settings = self.settings(for: uri) {
-          changedFiles[uri] = FileBuildSettingsChange(settings)
-        } else {
-          changedFiles[uri] = .removedOrUnavailable
-        }
+        changedFiles.insert(uri)
       }
       await delegate.fileBuildSettingsChanged(changedFiles)
     }
diff --git a/Sources/SKCore/FallbackBuildSystem.swift b/Sources/SKCore/FallbackBuildSystem.swift
index c03bfb44..25b20f57 100644
--- a/Sources/SKCore/FallbackBuildSystem.swift
+++ b/Sources/SKCore/FallbackBuildSystem.swift
@@ -62,9 +62,8 @@ public final class FallbackBuildSystem: BuildSystem {
   public func registerForChangeNotifications(for uri: DocumentURI, language: Language) {
     guard let delegate = self.delegate else { return }
 
-    let settings = self.buildSettings(for: uri, language: language)
     Task {
-      await delegate.fileBuildSettingsChanged([uri: FileBuildSettingsChange(settings)])
+      await delegate.fileBuildSettingsChanged([uri])
     }
   }
 
diff --git a/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift b/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
index df39d785..44e12940 100644
--- a/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
+++ b/Sources/SKSwiftPMWorkspace/SwiftPMWorkspace.swift
@@ -242,16 +242,7 @@ extension SwiftPMWorkspace {
     })
 
     guard let delegate = self.delegate else { return }
-    var changedFiles: [DocumentURI: FileBuildSettingsChange] = [:]
-    for (uri, language) in self.watchedFiles {
-      orLog {
-        if let settings = try self.buildSettings(for: uri, language: language) {
-          changedFiles[uri] = FileBuildSettingsChange(settings)
-        } else {
-          changedFiles[uri] = .removedOrUnavailable
-        }
-      }
-    }
+    let changedFiles = Set<DocumentURI>(self.watchedFiles.keys)
     await delegate.fileBuildSettingsChanged(changedFiles)
     await delegate.fileHandlingCapabilityChanged()
   }
@@ -316,11 +307,7 @@ extension SwiftPMWorkspace: SKCore.BuildSystem {
     } catch {
       log("error computing settings: \(error)")
     }
-    if let settings = settings {
-      await delegate.fileBuildSettingsChanged([uri: FileBuildSettingsChange(settings)])
-    } else {
-      await delegate.fileBuildSettingsChanged([uri: .removedOrUnavailable])
-    }
+    await delegate.fileBuildSettingsChanged([uri])
   }
 
   /// Unregister the given file for build-system level change notifications, such as command
diff --git a/Sources/SourceKitLSP/Clang/ClangLanguageServer.swift b/Sources/SourceKitLSP/Clang/ClangLanguageServer.swift
index e71cfa61..a4df45b1 100644
--- a/Sources/SourceKitLSP/Clang/ClangLanguageServer.swift
+++ b/Sources/SourceKitLSP/Clang/ClangLanguageServer.swift
@@ -404,7 +404,7 @@ extension ClangLanguageServerShim {
     // Send clangd the build settings for the new file. We need to do this before
     // sending the open notification, so that the initial diagnostics already
     // have build settings.
-    await documentUpdatedBuildSettings(note.textDocument.uri, change: .removedOrUnavailable)
+    await documentUpdatedBuildSettings(note.textDocument.uri)
     clangd.send(note)
   }
 
@@ -427,7 +427,7 @@ extension ClangLanguageServerShim {
 
   // MARK: - Build System Integration
 
-  public func documentUpdatedBuildSettings(_ uri: DocumentURI, change: FileBuildSettingsChange) async {
+  public func documentUpdatedBuildSettings(_ uri: DocumentURI) async {
     guard let url = uri.fileURL else {
       // FIXME: The clang workspace can probably be reworked to support non-file URIs.
       log("Received updated build settings for non-file URI '\(uri)'. Ignoring the update.")
diff --git a/Sources/SourceKitLSP/SourceKitServer.swift b/Sources/SourceKitLSP/SourceKitServer.swift
index 6f09a06d..bc620ecb 100644
--- a/Sources/SourceKitLSP/SourceKitServer.swift
+++ b/Sources/SourceKitLSP/SourceKitServer.swift
@@ -649,7 +649,7 @@ extension SourceKitServer: BuildSystemDelegate {
 
   // FIXME: (async) Make this method isolated once `BuildSystemDelegate` has been asyncified
   /// Non-async variant that executes `fileBuildSettingsChangedImpl` in a new task.
-  public nonisolated func fileBuildSettingsChanged(_ changedFiles: [DocumentURI: FileBuildSettingsChange]) {
+  public nonisolated func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) {
     Task {
       await self.fileBuildSettingsChangedImpl(changedFiles)
     }
@@ -659,10 +659,8 @@ extension SourceKitServer: BuildSystemDelegate {
   /// This has two primary cases:
   /// - Initial settings reported for a given file, now we can fully open it
   /// - Changed settings for an already open file
-  public func fileBuildSettingsChangedImpl(
-    _ changedFiles: [DocumentURI: FileBuildSettingsChange]
-  ) async {
-    for (uri, change) in changedFiles {
+  public func fileBuildSettingsChangedImpl(_ changedFiles: Set<DocumentURI>) async {
+    for uri in changedFiles {
       // Non-ready documents should be considered open even though we haven't
       // opened it with the language service yet.
       guard self.documentManager.openDocuments.contains(uri) else { continue }
@@ -687,7 +685,7 @@ extension SourceKitServer: BuildSystemDelegate {
         }
 
         // Notify the language server so it can apply the proper arguments.
-        await service.documentUpdatedBuildSettings(uri, change: change)
+        await service.documentUpdatedBuildSettings(uri)
 
         // Catch up on any queued notifications and requests.
         while !(documentToPendingQueue[uri]?.queue.isEmpty ?? true) {
@@ -708,7 +706,7 @@ extension SourceKitServer: BuildSystemDelegate {
       // Case 2: changed settings for an already open file.
       log("Build settings changed for opened file \(uri)")
       if let service = workspace.documentService[uri] {
-        await service.documentUpdatedBuildSettings(uri, change: change)
+        await service.documentUpdatedBuildSettings(uri)
       }
     }
   }
diff --git a/Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift b/Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift
index 4a0b44e6..6eaf99a9 100644
--- a/Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift
+++ b/Sources/SourceKitLSP/Swift/SwiftLanguageServer.swift
@@ -485,7 +485,7 @@ extension SwiftLanguageServer {
         response: dict, for: snapshot, compileCommand: compileCmd)
   }
 
-  public func documentUpdatedBuildSettings(_ uri: DocumentURI, change: FileBuildSettingsChange) async {
+  public func documentUpdatedBuildSettings(_ uri: DocumentURI) async {
     // We may not have a snapshot if this is called just before `openDocument`.
     guard let snapshot = self.documentManager.latestSnapshot(uri) else {
       return
diff --git a/Sources/SourceKitLSP/ToolchainLanguageServer.swift b/Sources/SourceKitLSP/ToolchainLanguageServer.swift
index 2cdce149..5964a857 100644
--- a/Sources/SourceKitLSP/ToolchainLanguageServer.swift
+++ b/Sources/SourceKitLSP/ToolchainLanguageServer.swift
@@ -70,7 +70,7 @@ public protocol ToolchainLanguageServer: AnyObject {
   /// Sent when the `BuildSystem` has resolved build settings, such as for the intial build settings
   /// or when the settings have changed (e.g. modified build system files). This may be sent before
   /// the respective `DocumentURI` has been opened.
-  func documentUpdatedBuildSettings(_ uri: DocumentURI, change: FileBuildSettingsChange) async
+  func documentUpdatedBuildSettings(_ uri: DocumentURI) async
 
   /// Sent when the `BuildSystem` has detected that dependencies of the given file have changed
   /// (e.g. header files, swiftmodule files, other compiler input files).
diff --git a/Tests/SKCoreTests/BuildServerBuildSystemTests.swift b/Tests/SKCoreTests/BuildServerBuildSystemTests.swift
index 7e2bcacd..d86d381b 100644
--- a/Tests/SKCoreTests/BuildServerBuildSystemTests.swift
+++ b/Tests/SKCoreTests/BuildServerBuildSystemTests.swift
@@ -98,9 +98,8 @@ final class TestDelegate: BuildSystemDelegate {
     }
   }
 
-  func fileBuildSettingsChanged(
-    _ changedFiles: [DocumentURI: FileBuildSettingsChange]) {
-    for (uri, _) in changedFiles {
+  func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) {
+    for uri in changedFiles {
       settingsExpectations[uri]?.fulfill()
     }
   }
diff --git a/Tests/SKCoreTests/BuildSystemManagerTests.swift b/Tests/SKCoreTests/BuildSystemManagerTests.swift
index 04be5a5e..033b2632 100644
--- a/Tests/SKCoreTests/BuildSystemManagerTests.swift
+++ b/Tests/SKCoreTests/BuildSystemManagerTests.swift
@@ -110,7 +110,7 @@ final class BuildSystemManagerTests: XCTestCase {
     bs.map[a] = nil
     let changed = expectation(description: "changed settings")
     await del.setExpected([(a, .swift, nil, changed, #file, #line)])
-    bsm.fileBuildSettingsChanged([a: .removedOrUnavailable])
+    bsm.fileBuildSettingsChanged([a])
     try await fulfillmentOfOrThrow([changed])
   }
 
@@ -133,7 +133,7 @@ final class BuildSystemManagerTests: XCTestCase {
     bs.map[a] = FileBuildSettings(compilerArguments: ["x"])
     let changed = expectation(description: "changed settings")
     await del.setExpected([(a, .swift, bs.map[a]!, changed, #file, #line)])
-    bsm.fileBuildSettingsChanged([a: .modified(bs.map[a]!)])
+    bsm.fileBuildSettingsChanged([a])
     try await fulfillmentOfOrThrow([changed])
   }
 
@@ -158,13 +158,13 @@ final class BuildSystemManagerTests: XCTestCase {
     bs.map[a] = FileBuildSettings(compilerArguments: ["non-fallback", "args"])
     let changed = expectation(description: "changed settings")
     await del.setExpected([(a, .swift, bs.map[a]!, changed, #file, #line)])
-    bsm.fileBuildSettingsChanged([a: .modified(bs.map[a]!)])
+    bsm.fileBuildSettingsChanged([a])
     try await fulfillmentOfOrThrow([changed])
 
     bs.map[a] = nil
     let revert = expectation(description: "revert to fallback settings")
     await del.setExpected([(a, .swift, fallbackSettings, revert, #file, #line)])
-    bsm.fileBuildSettingsChanged([a: .removedOrUnavailable])
+    bsm.fileBuildSettingsChanged([a])
     try await fulfillmentOfOrThrow([revert])
   }
 
@@ -196,7 +196,7 @@ final class BuildSystemManagerTests: XCTestCase {
     bs.map[b] = FileBuildSettings(compilerArguments: ["yy"])
     let changed = expectation(description: "changed settings")
     await del.setExpected([(a, .swift, bs.map[a]!, changed, #file, #line)])
-    bsm.fileBuildSettingsChanged([a: .modified(bs.map[a]!)])
+    bsm.fileBuildSettingsChanged([a])
     try await fulfillmentOfOrThrow([changed])
 
     // Test multiple changes.
@@ -208,10 +208,7 @@ final class BuildSystemManagerTests: XCTestCase {
       (a, .swift, bs.map[a]!, changedBothA, #file, #line),
       (b, .swift, bs.map[b]!, changedBothB, #file, #line),
     ])
-    bsm.fileBuildSettingsChanged([
-      a:. modified(bs.map[a]!),
-      b: .modified(bs.map[b]!)
-    ])
+    bsm.fileBuildSettingsChanged([a, b])
     try await fulfillmentOfOrThrow([changedBothA, changedBothB])
   }
 
@@ -245,9 +242,7 @@ final class BuildSystemManagerTests: XCTestCase {
     bs.map[b] = nil
     let changed = expectation(description: "changed settings")
     await del.setExpected([(b, .swift, nil, changed, #file, #line)])
-    bsm.fileBuildSettingsChanged([
-      b: .removedOrUnavailable
-    ])
+    bsm.fileBuildSettingsChanged([b])
     try await fulfillmentOfOrThrow([changed])
   }
 
@@ -354,7 +349,7 @@ final class BuildSystemManagerTests: XCTestCase {
       (h1, .c, newArgsH1, changed1, #file, #line),
       (h2, .c, newArgsH2, changed2, #file, #line),
     ])
-    bsm.fileBuildSettingsChanged([cpp: .modified(bs.map[cpp]!)])
+    bsm.fileBuildSettingsChanged([cpp])
 
     try await fulfillmentOfOrThrow([changed1, changed2])
   }
@@ -403,11 +398,7 @@ final class BuildSystemManagerTests: XCTestCase {
     await bsm.unregisterForChangeNotifications(for: c)
     // At this point only b is registered, but that can race with notifications,
     // so ensure nothing bad happens and we still get the notification for b.
-    bsm.fileBuildSettingsChanged([
-      a: .modified(bs.map[a]!),
-      b: .modified(bs.map[b]!),
-      c: .modified(bs.map[c]!)
-    ])
+    bsm.fileBuildSettingsChanged([a, b, c])
 
     try await fulfillmentOfOrThrow([changedB])
   }
@@ -484,8 +475,7 @@ class ManualBuildSystem: BuildSystem {
   }
 
   func registerForChangeNotifications(for uri: DocumentURI, language: Language) async {
-    let settings = self.buildSettings(for: uri, language: language)
-    await self.delegate?.fileBuildSettingsChanged([uri: FileBuildSettingsChange(settings)])
+    await self.delegate?.fileBuildSettingsChanged([uri])
   }
 
   func unregisterForChangeNotifications(for: DocumentURI) {
@@ -536,8 +526,8 @@ private actor BSMDelegate: BuildSystemDelegate {
     }()
   }
 
-  func fileBuildSettingsChanged(_ changes: [DocumentURI: FileBuildSettingsChange]) async {
-    for (uri, _) in changes {
+  func fileBuildSettingsChanged(_ changedFiles: Set<DocumentURI>) async {
+    for uri in changedFiles {
       guard let expected = expected.first(where: { $0.uri == uri }) else {
         XCTFail("unexpected settings change for \(uri)")
         continue
diff --git a/Tests/SourceKitLSPTests/BuildSystemTests.swift b/Tests/SourceKitLSPTests/BuildSystemTests.swift
index 3d77efa6..8dc921cf 100644
--- a/Tests/SourceKitLSPTests/BuildSystemTests.swift
+++ b/Tests/SourceKitLSPTests/BuildSystemTests.swift
@@ -55,13 +55,12 @@ final class TestBuildSystem: BuildSystem {
     watchedFiles.insert(uri)
 
     // Inform our delegate of settings for the file if they're available.
-    guard let delegate = self.delegate,
-          let settings = self.buildSettingsByFile[uri] else {
+    guard let delegate = self.delegate else {
       return
     }
 
     Task {
-      await delegate.fileBuildSettingsChanged([uri: .modified(settings)])
+      await delegate.fileBuildSettingsChanged([uri])
     }
   }
 
@@ -196,7 +195,7 @@ final class BuildSystemTests: XCTestCase {
       expectation.fulfill()
     }
 
-    await buildSystem.delegate?.fileBuildSettingsChanged([doc: .modified(newSettings)])
+    await buildSystem.delegate?.fileBuildSettingsChanged([doc])
 
     try await fulfillmentOfOrThrow([expectation])
   }
@@ -251,7 +250,7 @@ final class BuildSystemTests: XCTestCase {
       XCTAssertEqual(note.params.diagnostics.count, 0)
       expectation.fulfill()
     }
-    await buildSystem.delegate?.fileBuildSettingsChanged([doc: .modified(newSettings)])
+    await buildSystem.delegate?.fileBuildSettingsChanged([doc])
 
     try await fulfillmentOfOrThrow([expectation])
   }
@@ -304,7 +303,7 @@ final class BuildSystemTests: XCTestCase {
       expectation.fulfill()
     }
 
-    await buildSystem.delegate?.fileBuildSettingsChanged([doc: .modified(newSettings)])
+    await buildSystem.delegate?.fileBuildSettingsChanged([doc])
 
     try await fulfillmentOfOrThrow([expectation])
   }
@@ -358,7 +357,7 @@ final class BuildSystemTests: XCTestCase {
       XCTAssertEqual(note.params.diagnostics.count, 2)
       expectation.fulfill()
     }
-    await buildSystem.delegate?.fileBuildSettingsChanged([doc: .modified(primarySettings)])
+    await buildSystem.delegate?.fileBuildSettingsChanged([doc])
 
     try await fulfillmentOfOrThrow([expectation])
   }
@@ -388,7 +387,7 @@ final class BuildSystemTests: XCTestCase {
 
     // Modify the build settings and inform the SourceKitServer.
     // This shouldn't trigger new diagnostics since nothing actually changed (false alarm).
-    await buildSystem.delegate?.fileBuildSettingsChanged([doc: .removedOrUnavailable])
+    await buildSystem.delegate?.fileBuildSettingsChanged([doc])
 
     let expectation = XCTestExpectation(description: "refresh doesn't occur")
     expectation.isInverted = true