Fix a retain cycle

I don’t remember what the exact retain cycle was after fixing it.

Author: ahoppen

Sources/SKCore/BuildSystemManager.swift

@@ -238,7 +238,7 @@ extension BuildSystemManager: BuildSystemDelegate {
   }
 }
 
-extension BuildSystemManager: MainFilesDelegate {
+extension BuildSystemManager {
   // FIXME: Consider debouncing/limiting this, seems to trigger often during a build.
   /// Checks if there are any files in `mainFileAssociations` where the main file
   /// that we have stored has changed.

Sources/SKCore/MainFilesProvider.swift

@@ -25,10 +25,3 @@ public protocol MainFilesProvider: AnyObject {
   /// ```
   func mainFilesContainingFile(_: DocumentURI) async -> Set<DocumentURI>
 }
-
-/// Delegate that responds to possible main file changes.
-public protocol MainFilesDelegate: AnyObject {
-
-  /// The mapping from files to main files (may have) changed.
-  func mainFilesChanged() async
-}

Sources/SourceKitLSP/SourceKitIndexDelegate.swift

@@ -23,7 +23,7 @@ public actor SourceKitIndexDelegate: IndexDelegate {
   let queue = AsyncQueue<Serial>()
 
   /// Registered `MainFilesDelegate`s to notify when main files change.
-  var mainFilesDelegates: [MainFilesDelegate] = []
+  var mainFilesChangedCallbacks: [() async -> Void] = []
 
   /// The count of pending unit events. Whenever this transitions to 0, it represents a time where
   /// the index finished processing known events. Of course, that may have already changed by the
@@ -62,20 +62,16 @@ public actor SourceKitIndexDelegate: IndexDelegate {
   }
 
   func _indexChanged() {
-    for delegate in mainFilesDelegates {
+    for callback in mainFilesChangedCallbacks {
       queue.async {
-        await delegate.mainFilesChanged()
+        await callback()
       }
     }
   }
 
   /// Register a delegate to receive notifications when main files change.
-  public func registerMainFileChanged(_ delegate: MainFilesDelegate) {
-    mainFilesDelegates.append(delegate)
+  public func addMainFileChangedCallback(_ callback: @escaping () async -> Void) {
+    mainFilesChangedCallbacks.append(callback)
   }
 
-  /// Un-register a delegate to receive notifications when main files change.
-  public func unregisterMainFileChanged(_ delegate: MainFilesDelegate) {
-    mainFilesDelegates.removeAll(where: { $0 === delegate })
-  }
 }

Sources/SourceKitLSP/Workspace.swift

@@ -88,7 +88,9 @@ public final class Workspace {
       fallbackBuildSystem: FallbackBuildSystem(buildSetup: buildSetup),
       mainFilesProvider: index
     )
-    await indexDelegate?.registerMainFileChanged(buildSystemManager)
+    await indexDelegate?.addMainFileChangedCallback { [weak self] in
+      await self?.buildSystemManager.mainFilesChanged()
+    }
   }
 
   /// Creates a workspace for a given root `URL`, inferring the `ExternalWorkspace` if possible.