Fix a bug in model merging

If the same model was set in the configuration
and the container, the init would produce a new
model, even though that wasn't necessary.
This would then produce the "model type" claimed
by multiple entity descriptions issue.

Author: helje5

Sources/ManagedModels/Container/NSPersistentContainer+Data.swift

@@ -1,6 +1,6 @@
 //
 //  Created by Helge Heß.
-//  Copyright © 2023 ZeeZide GmbH.
+//  Copyright © 2023-2024 ZeeZide GmbH.
 //
 
 import CoreData
@@ -27,9 +27,21 @@ extension NSPersistentContainer {
     precondition(migrationPlan == nil, "Migration plans not yet supported")
 
     let combinedModel : NSManagedObjectModel = {
-      let allModels = [ model ] + configurations.compactMap { $0.schema }
+      guard let firstConfig = configurations.first else { return model }
+      if configurations.count == 1,
+         firstConfig.schema == nil || firstConfig.schema == model
+      {
+        return model
+      }
+      
+      var allModels = [ ObjectIdentifier : NSManagedObjectModel ]()
+      allModels[ObjectIdentifier(model)] = model
+      for config in configurations {
+        guard let model = config.schema else { continue }
+        allModels[ObjectIdentifier(model)] = model
+      }
       guard allModels.count > 1 else { return model }
-      let merged = NSManagedObjectModel(byMerging: allModels)
+      let merged = NSManagedObjectModel(byMerging: Array(allModels.values))
       assert(merged != nil, "Could not combine object models: \(allModels)")
       return merged ?? model
     }()
@@ -84,6 +96,7 @@ extension NSPersistentContainer {
 
 public extension NSPersistentContainer {
 
+  @inlinable
   convenience init(for     model  : NSManagedObjectModel,
                    migrationPlan  : SchemaMigrationPlan.Type? = nil,
                    configurations : ModelConfiguration...) throws
@@ -92,6 +105,7 @@ public extension NSPersistentContainer {
                   configurations: configurations)
   }
 
+  @inlinable
   convenience init(for      types : any PersistentModel.Type...,
                    migrationPlan  : SchemaMigrationPlan.Type? = nil,
                    configurations : ModelConfiguration...) throws

Sources/ManagedModels/SchemaCompatibility/NSManagedObjectModel+Data.swift

@@ -1,6 +1,6 @@
 //
 //  Created by Helge Heß.
-//  Copyright © 2023 ZeeZide GmbH.
+//  Copyright © 2023-2024 ZeeZide GmbH.
 //
 
 import CoreData
@@ -36,7 +36,7 @@ public extension NSManagedObjectModel {
 
 // MARK: - Cached ManagedObjectModels
 
-private let lock = NSLock()
+private let lock = NSLock() // TODO: Use new UnfairLock if available
 #if swift(>=5.10)
 nonisolated(unsafe) 
 private var map = [ Set<ObjectIdentifier> : NSManagedObjectModel ]()
@@ -48,14 +48,31 @@ nonisolated private let sharedBuilder = SchemaBuilder()
 
 public extension NSManagedObjectModel {
 
-  /// A cached version of the initializer.
-  static func model(for versionedSchema: VersionedSchema.Type) 
+  /**
+   * This caches a model for the types in the given `VersionedSchema`.
+   * I.e. it will return the same `NSManagedObjectModel` when given the same
+   * types.
+   *
+   * - Parameters:
+   *   - versionedSchema: The versioned schema to derive the model from.
+   * - Returns:           A `NSManagedObjectModel` representing the schema.
+   */
+  @inlinable
+  static func model(for versionedSchema: VersionedSchema.Type)
               -> NSManagedObjectModel
   {
     model(for: versionedSchema.models)
   }
 
-  /// A cached version of the initializer.
+  /**
+   * This caches a model for the types passed in.
+   * I.e. it will return the same `NSManagedObjectModel` when given the same
+   * types.
+   *
+   * - Parameters:
+   *   - types: A set of `PersistentModel` types, e.g. `[Person.self]`.
+   * - Returns: A `NSManagedObjectModel` representing the types.
+   */
   static func model(for types: [ any PersistentModel.Type ])
               -> NSManagedObjectModel
   {