force true lightweight migration

Sources/DataStack+Migration.swift

@@ -575,6 +575,7 @@ public extension DataStack {
                                 sourceModel: sourceModel,
                                 destinationModel: destinationModel,
                                 mappingModel: mappingModel,
+                                migrationType: migrationType,
                                 progress: childProgress
                             )
                         }
@@ -679,9 +680,33 @@ public extension DataStack {
         return nil
     }
     
-    private func startMigrationForStorage<T: LocalStorage>(_ storage: T, sourceModel: NSManagedObjectModel, destinationModel: NSManagedObjectModel, mappingModel: NSMappingModel, progress: Progress) throws {
+    private func startMigrationForStorage<T: LocalStorage>(_ storage: T, sourceModel: NSManagedObjectModel, destinationModel: NSManagedObjectModel, mappingModel: NSMappingModel, migrationType: MigrationType, progress: Progress) throws {
         
         let fileURL = storage.fileURL
+        if case .lightweight = migrationType {
+
+            do {
+
+                _ = try withExtendedLifetime(NSPersistentStoreCoordinator(managedObjectModel: destinationModel)) { (coordinator: NSPersistentStoreCoordinator) in
+
+                    try coordinator.addPersistentStoreSynchronously(
+                        type(of: storage).storeType,
+                        configuration: storage.configuration,
+                        URL: fileURL,
+                        options: storage.dictionary(
+                            forOptions: storage.localStorageOptions.union(.allowSynchronousLightweightMigration)
+                        )
+                    )
+                }
+                _ = try? storage.cs_finalizeStorageAndWait(soureModelHint: destinationModel)
+                progress.completedUnitCount = progress.totalUnitCount
+                return
+            }
+            catch {
+
+                // try manual migration
+            }
+        }
 
         let temporaryDirectoryURL = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
             .appendingPathComponent(Bundle.main.bundleIdentifier ?? "com.CoreStore.DataStack")

Sources/NSPersistentStoreCoordinator+Setup.swift

@@ -72,15 +72,13 @@ internal extension NSPersistentStoreCoordinator {
     }
     
     @nonobjc
-    internal func addPersistentStoreSynchronously(_ storeType: String, configuration: ModelConfiguration, URL storeURL: URL?, options: [NSObject : AnyObject]?) throws -> NSPersistentStore {
+    internal func addPersistentStoreSynchronously(_ storeType: String, configuration: ModelConfiguration, URL storeURL: URL?, options: [AnyHashable: Any]?) throws -> NSPersistentStore {
         
-        var store: NSPersistentStore?
+        return try self.performSynchronously {
-        var storeError: NSError?
-        self.performSynchronously {
             
             do {
                 
-                store = try self.addPersistentStore(
+                return try self.addPersistentStore(
                     ofType: storeType,
                     configurationName: configuration,
                     at: storeURL,
@@ -89,13 +87,8 @@ internal extension NSPersistentStoreCoordinator {
             }
             catch {
                 
-                storeError = error as NSError
+                throw CoreStoreError(error)
             }
         }
-        if let store = store {
-            
-            return store
-        }
-        throw CoreStoreError(storeError)
     }
 }