Refactor FXIOS-12796 [Swift 6 Migration] Address several global shared singleton warnings (#30314)

* Annotate global singleton types as @unchecked Sendable with FIXMEs.

* Make some global singleton types actually Sendable.

* Fix a few more Sendable types.

* Fix some random warnings on the repo when strict checking is off to resolve warning count issues in Bitrise.

* Fix for unit test that didn't make much sense (?) and had a concurrency error.

Author: ih-codes

firefox-ios/Client/Application/WebServer.swift

@@ -13,8 +13,9 @@ protocol WebServerProtocol {
     func start() throws -> Bool
 }
 
-class WebServer: WebServerProtocol {
-    private var logger: Logger
+// FIXME: FXIOS-13989 Make truly thread safe
+final class WebServer: WebServerProtocol, @unchecked Sendable {
+    private let logger: Logger
     static let WebServerSharedInstance = WebServer()
 
     class var sharedInstance: WebServer {

firefox-ios/Client/ContentBlocker/TrackingProtectionPageStats.swift

@@ -41,7 +41,8 @@ struct TPPageStats {
     }
 }
 
-class TPStatsBlocklistChecker {
+// FIXME: FXIOS-13985 Make truly thread safe
+class TPStatsBlocklistChecker: @unchecked Sendable {
     static let shared = TPStatsBlocklistChecker()
 
     // Initialized async, is non-nil when ready to be used.

firefox-ios/Client/FeatureFlags/LegacyFeatureFlagsManager.swift

@@ -26,7 +26,8 @@ enum FlaggableFeatureCheckOptions {
     case userOnly
 }
 
-class LegacyFeatureFlagsManager: HasNimbusFeatureFlags {
+// FIXME: FXIOS-13986 Make truly thread safe
+class LegacyFeatureFlagsManager: HasNimbusFeatureFlags, @unchecked Sendable {
     /// This Singleton should only be accessed directly in places where the
     /// `FeatureFlaggable` is not available. Otherwise, access to the feature
     /// flags system should be done through the protocol, giving access to the

firefox-ios/Client/Frontend/Browser/SearchEngines/DefaultSearchEngineProvider.swift

@@ -7,7 +7,7 @@ import Common
 
 typealias SearchEngineCompletion = @MainActor @Sendable (SearchEnginePrefs, [OpenSearchEngine]) -> Void
 
-protocol SearchEngineProvider {
+protocol SearchEngineProvider: Sendable {
     /// Takes a list of custom search engines (added by the user) along with an ordered
     /// engine name list (to provide sorting) which is stored in Prefs, and returns a
     /// a final list of search engines.
@@ -38,7 +38,7 @@ struct SearchEnginePrefs {
     let version: SearchEngineOrderingPrefsVersion
 }
 
-class DefaultSearchEngineProvider: SearchEngineProvider {
+final class DefaultSearchEngineProvider: SearchEngineProvider {
     private let logger: Logger
 
     init(logger: Logger = DefaultLogger.shared) {
@@ -101,7 +101,7 @@ class DefaultSearchEngineProvider: SearchEngineProvider {
 
     private func getUnorderedBundledEnginesFor(locale: Locale,
                                                possibleLanguageIdentifier: [String],
-                                               completion: @escaping ([OpenSearchEngine]) -> Void ) {
+                                               completion: @escaping @Sendable ([OpenSearchEngine]) -> Void ) {
         let region = locale.regionCode ?? "US"
         let parser = OpenSearchParser(pluginMode: true)
 

firefox-ios/Client/Frontend/Browser/SearchEngines/OpenSearchParser.swift

@@ -10,7 +10,7 @@ import Fuzi
 /// the Firefox-specific search plugin format.
 ///
 /// OpenSearch spec: http://www.opensearch.org/Specifications/OpenSearch/1.1
-class OpenSearchParser {
+final class OpenSearchParser: Sendable {
     private let pluginMode: Bool
     private let userInterfaceIdiom: UIUserInterfaceIdiom
     private let typeSearch = "text/html"

firefox-ios/Client/Frontend/Browser/SearchEngines/SearchEnginesManager.swift

@@ -291,7 +291,7 @@ class SearchEnginesManager: SearchEnginesManagerProvider {
         }
     }
 
-    func deleteCustomEngine(_ engine: OpenSearchEngine, completion: @escaping () -> Void) {
+    func deleteCustomEngine(_ engine: OpenSearchEngine, completion: @escaping @Sendable () -> Void) {
         // We can't delete a preinstalled engine or an engine that is currently the default.
         guard engine.isCustomEngine && !isEngineDefault(engine) else { return }
 

firefox-ios/Client/Frontend/Settings/SearchSettingsTableViewController.swift

@@ -635,11 +635,14 @@ final class SearchSettingsTableViewController: ThemedTableViewController, Featur
             let index = indexPath.item + 1
             let engine = model.orderedEngines[index]
 
-            model.deleteCustomEngine(engine) { [weak self] in
-                tableView.deleteRows(at: [indexPath], with: .right)
-                // Change navigationItem's right button item title to Edit and disable the edit button
-                // once the deletion is done
-                self?.setEditing(false, animated: true)
+            model.deleteCustomEngine(engine) {
+                ensureMainThread { [weak self] in
+                    self?.tableView.deleteRows(at: [indexPath], with: .right)
+
+                    // Change navigationItem's right button item title to Edit and disable the edit button
+                    // once the deletion is done
+                    self?.setEditing(false, animated: true)
+                }
             }
 
             // End editing if we are no longer edit since we've deleted all editable cells.

firefox-ios/Client/Frontend/TrackingProtection/TrackingProtectionViewController.swift

@@ -197,9 +197,9 @@ class TrackingProtectionViewController: UIViewController,
         updateBlockedTrackersCount()
         updateConnectionStatus()
         applyTheme()
-        getCertificates(for: model.url) { [weak self] certificates in
+        getCertificates(for: model.url) { certificates in
             if let certificates {
-                ensureMainThread {
+                ensureMainThread { [weak self] in
                     self?.model.certificates = certificates
                 }
             }

firefox-ios/Client/Nimbus/NimbusFeatureFlagLayer.swift

@@ -4,7 +4,7 @@
 
 import Foundation
 
-final class NimbusFeatureFlagLayer {
+final class NimbusFeatureFlagLayer: Sendable {
     // MARK: - Public methods
     public func checkNimbusConfigFor(_ featureID: NimbusFeatureFlagID,
                                      from nimbus: FxNimbus = FxNimbus.shared

firefox-ios/Client/Nimbus/NimbusManager.swift

@@ -20,16 +20,16 @@ extension HasNimbusSearchBar {
     }
 }
 
-class NimbusManager {
+final class NimbusManager: Sendable {
     // MARK: - Singleton
 
     /// To help with access control, we should use protocols to access the required
     /// layers. `.shared` should, ideally, never be directly accessed.
     static let shared = NimbusManager()
 
     // MARK: - Properties
-    var featureFlagLayer: NimbusFeatureFlagLayer
-    var bottomSearchBarLayer: NimbusSearchBarLayer
+    let featureFlagLayer: NimbusFeatureFlagLayer
+    let bottomSearchBarLayer: NimbusSearchBarLayer
 
     init(with featureFlagLayer: NimbusFeatureFlagLayer = NimbusFeatureFlagLayer(),
          bottomSearchBarLayer: NimbusSearchBarLayer = NimbusSearchBarLayer()