Move CI to Xcode 15.3, first-pass concurrency-correctness (#23)

First pass at Swift concurrency checking.  Problem is that Core Data itself
is not updated.

Remaining problems currently easily unworkaroundable:
* Container metadata [String:Any] — need a Sendable version of this
* NSPC::loadPersistentStores() — the callback semantics need formalizing in the new world

In addition having to @preconcurrency import CoreData in a bunch of places.

.github/workflows/test.yml

@@ -11,10 +11,11 @@ on:
 jobs:
   macos:
     name: Tests
-    runs-on: macos-13
-    env:
-      DEVELOPER_DIR: /Applications/Xcode_15.0.app/Contents/Developer
+    runs-on: macos-14
     steps:
+      - uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: 15.3
       - uses: actions/checkout@v4
       - name: Tests
         run: xcodebuild build test -project TMLPersistentContainer.xcodeproj -scheme TMLPersistentContainer-macOS -enableCodeCoverage YES

Sources/MigrationError.swift

@@ -6,7 +6,7 @@
 //
 
 import Foundation
-import CoreData
+@preconcurrency import CoreData
 
 /// Errors that can occur preventing persistent store loading, passed into the callback given to
 /// `PersistentContainer.loadPersistentStores(...)` or

Sources/ModelVersionOrder.swift

@@ -14,7 +14,7 @@ import CoreData
 /// Note that the *model version* here is the part of its filename before '.xcdatamodel' --
 /// *not* the optional 'Model Version Identifier' that you can set in the model's properties panel.
 @available(macOS 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
-public enum ModelVersionOrder {
+public enum ModelVersionOrder: Sendable {
 
     /// Compare the model versions directly, but interpreting numbers like a human -- using
     /// the `NSString.CompareOptions.numeric` algorithm, meaning that for example `MyModel_v2`
@@ -41,7 +41,7 @@ public enum ModelVersionOrder {
     case pairList([(String,String)])
 
     /// Use a different order for different stores under the same container.
-    case perStore((NSPersistentStoreDescription) -> ModelVersionOrder)
+    case perStore(@Sendable (NSPersistentStoreDescription) -> ModelVersionOrder)
 }
 
 @available(macOS 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)

Sources/PersistentContainer.swift

@@ -6,7 +6,7 @@
 //
 
 import Foundation
-import CoreData
+@preconcurrency import CoreData
 
 @available(macOS 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
 protocol PersistentContainerProtocol: PersistentContainerMigratable {
@@ -46,18 +46,16 @@ extension PersistentContainerProtocol {
     func loadPersistentStoresHelper(invokeCoreDataClosure: @escaping ((_ block: @escaping (NSPersistentStoreDescription, Error?) -> ()) -> Void), completionHandler block: @escaping (NSPersistentStoreDescription, Error?) -> ()) {
         // Filter out the stores that need loading to replicate the superclass API
         // There are probably only a handful at most of these so no need to be terribly efficient
-        let storeURLs = persistentStoreCoordinator.persistentStores.compactMap { $0.url }
+        let storeURLs = persistentStoreCoordinator.persistentStores.compactMap(\.url)
 
         if storeURLs.count > 0 {
             log(.info, "Already have loaded stores associated with container: \(storeURLs)")
         }
 
-        var storesToLoad: [NSPersistentStoreDescription] = []
-
-        persistentStoreDescriptions.forEach { description in
+        let storesToLoad = persistentStoreDescriptions.filter { description in
             guard let storeURL = description.url else {
                 log(.info, "Not migrating store \(description) because no URL present")
-                return
+                return false
             }
             if !storeURL.isFileURL {
                 log(.info, "Not migrating store \(description) because not a file:// URL")
@@ -66,8 +64,9 @@ extension PersistentContainerProtocol {
             } else if storeURLs.contains(description.fileURL) {
                 log(.info, "Not migrating store \(storeURL) because already loaded.")
             } else {
-                storesToLoad.append(description)
+                return true
             }
+            return false
         }
 
         guard storesToLoad.count > 0 else {
@@ -82,7 +81,7 @@ extension PersistentContainerProtocol {
         }
 
         // Helper to deal with the sync/async version....
-        func doStoreMigration() {
+        @Sendable func doStoreMigration() {
             var failures = false
 
             migrateStores(descriptions: storesToLoad) { desc, error in

TMLPersistentContainer.xcodeproj/project.pbxproj

@@ -1057,6 +1057,7 @@
 				SDKROOT = iphoneos;
 				"SWIFT_ACTIVE_COMPILATION_CONDITIONS[arch=*]" = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_STRICT_CONCURRENCY = complete;
 				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
@@ -1116,6 +1117,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
+				SWIFT_STRICT_CONCURRENCY = complete;
 				SWIFT_SWIFT3_OBJC_INFERENCE = Default;
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";