Build in Swift 6 language mode when supported

CHANGELOG.md

@@ -1,7 +1,25 @@
 x.y.z Release notes (yyyy-MM-dd)
 =============================================================
+
+The minimum supported version of Xcode is now 15.3.
+
 ### Enhancements
-* None.
+* Build in Swift 6 language mode when using Xcode 16. Libraries build in Swift
+  6 mode can be consumed by apps built in Swift 5 mode, so this should not have
+  any immediate effects beyond eliminating some warnings and ensuring that all
+  Realm APIs can be used in Swift 6 mode. Some notes about using Realm Swift in
+  Swift 6:
+  - `try await Realm(actor: actor)` has been replaced with `try await Realm.open()` to work around (swift bug link). The actor is now automatically inferred.
+  - `@ThreadSafe` is not usable as a property wrapper on local variables and
+  function arguments in Swift 6 mode. Sendability checking for property
+  wrappers never got implemented due to them being quietly deprecated in favor
+  of macros. It can still be used as a property wrapper for class properties
+  and as a manual wrapper locally, but note that it does not combine well with
+  actor-isolated Realms.
+  - In Swift 6 mode a few mongo client functions have changed from returning
+  `[AnyHashable: Any]` to `Document`. These should have been `Document` all
+  along, and the old return type no longer compiles due to not being Sendable.
+
 
 ### Fixed
 * <How to hit and notice issue? what was the impact?> ([#????](https://github.com/realm/realm-swift/issues/????), since v?.?.?)
@@ -14,7 +32,7 @@ x.y.z Release notes (yyyy-MM-dd)
 * APIs are backwards compatible with all previous releases in the 10.x.y series.
 * Carthage release for Swift is built with Xcode 15.4.0.
 * CocoaPods: 1.10 or later.
-* Xcode: 15.1.0-16 beta 5.
+* Xcode: 15.3.0-16 beta 5.
 
 ### Internal
 * Upgraded realm-core from ? to ?

Package.swift

@@ -1,11 +1,17 @@
-// swift-tools-version:5.7
+// swift-tools-version:5.10
 
 import PackageDescription
 import Foundation
 
 let coreVersion = Version("14.12.0")
 let cocoaVersion = Version("10.53.0")
 
+#if compiler(>=6)
+let swiftVersion = [SwiftVersion.version("6")]
+#else
+let swiftVersion = [SwiftVersion.v5]
+#endif
+
 let cxxSettings: [CXXSetting] = [
     .headerSearchPath("."),
     .headerSearchPath("include"),
@@ -392,5 +398,6 @@ let package = Package(
             ]
         )
     ],
+    swiftLanguageVersions: swiftVersion,
     cxxLanguageStandard: .cxx20
 )

Realm.xcodeproj/project.pbxproj

@@ -2895,6 +2895,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 3FEC91542A4B59A40044BFF5 /* Static.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Static;
 		};
@@ -2909,6 +2910,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 5D660FBD1BE98BEF0021E04F /* RealmSwift.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Static;
 		};
@@ -3087,13 +3089,15 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 5D660FBD1BE98BEF0021E04F /* RealmSwift.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Debug;
 		};
 		5D660FD31BE98C560021E04F /* Release */ = {
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 5D660FBD1BE98BEF0021E04F /* RealmSwift.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Release;
 		};
@@ -3233,13 +3237,15 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 5D659E6E1BE0398E006515A0 /* Debug.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Debug;
 		};
 		E8D89BAD1955FC6D00CF2B9A /* Release */ = {
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 5D659E6F1BE0398E006515A0 /* Release.xcconfig */;
 			buildSettings = {
+				SWIFT_VERSION = 6.0;
 			};
 			name = Release;
 		};

Realm/ObjectServerTests/AsyncSyncTests.swift

@@ -279,9 +279,14 @@ class AsyncAwaitSyncTests: SwiftSyncTestCase {
 
         let configuration = try configuration()
         func isolatedOpen(_ actor: isolated CustomExecutorActor) async throws {
+#if compiler(<6)
             _ = try await Realm(configuration: configuration, actor: actor, downloadBeforeOpen: .always)
+#else
+            _ = try await Realm.open(configuration: configuration, downloadBeforeOpen: .always)
+#endif
         }
 
+
         // Try opening the Realm with the Task being cancelled at every possible
         // point between executor invocations. This doesn't really test that
         // cancellation is *correct*; just that cancellation never results in
@@ -442,6 +447,7 @@ class AsyncAwaitSyncTests: SwiftSyncTestCase {
         XCTAssertEqual(app.allUsers.count, 0)
     }
 
+    @MainActor
     func testSwiftAddObjectsAsync() async throws {
         let realm = try await openRealm()
         checkCount(expected: 0, realm, SwiftPerson.self)
@@ -535,10 +541,11 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
         try await populateSwiftPerson(5)
 
         let user = try await createUser()
+        let name = self.name
         try await Task {
             var config = user.flexibleSyncConfiguration(initialSubscriptions: { subs in
                 subs.append(QuerySubscription<SwiftPerson> {
-                    $0.age > 0 && $0.firstName == self.name
+                    $0.age > 0 && $0.firstName == name
                 })
             })
             config.objectTypes = [SwiftPerson.self]
@@ -557,7 +564,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
         var config = user.flexibleSyncConfiguration(initialSubscriptions: { subs in
             subs.append(QuerySubscription<SwiftPerson> {
-                $0.age > 5 && $0.firstName == self.name
+                $0.age > 5 && $0.firstName == name
             })
         })
         config.objectTypes = [SwiftPerson.self]
@@ -567,7 +574,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
         var config2 = user.flexibleSyncConfiguration(initialSubscriptions: { subs in
             subs.append(QuerySubscription<SwiftPerson> {
-                $0.age > 0 && $0.firstName == self.name
+                $0.age > 0 && $0.firstName == name
             })
         })
         config2.objectTypes = [SwiftPerson.self]
@@ -621,9 +628,10 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
         }
 
         let user = try await createUser()
+        let name = self.name
         var config = user.flexibleSyncConfiguration(initialSubscriptions: { subscriptions in
             subscriptions.append(QuerySubscription<SwiftPerson>(name: "person_age_10") {
-                $0.age > 10 && $0.firstName == "\(self.name)"
+                $0.age > 10 && $0.firstName == "\(name)"
             })
         })
         config.objectTypes = [SwiftPerson.self]
@@ -639,10 +647,11 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
     @MainActor
     func testFlexibleSyncInitialSubscriptionsNotRerunOnOpen() async throws {
+        let name = self.name
         let user = try await createUser()
         var config = user.flexibleSyncConfiguration(initialSubscriptions: { subscriptions in
             subscriptions.append(QuerySubscription<SwiftPerson>(name: "person_age_10") {
-                $0.age > 10 && $0.firstName == "\(self.name)"
+                $0.age > 10 && $0.firstName == "\(name)"
             })
         })
         config.objectTypes = [SwiftPerson.self]
@@ -657,10 +666,11 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
     @MainActor
     func testFlexibleSyncInitialSubscriptionsRerunOnOpenNamedQuery() async throws {
         let user = try await createUser()
+        let name = self.name
         var config = user.flexibleSyncConfiguration(initialSubscriptions: { subscriptions in
             if subscriptions.first(named: "person_age_10") == nil {
                 subscriptions.append(QuerySubscription<SwiftPerson>(name: "person_age_10") {
-                    $0.age > 20 && $0.firstName == "\(self.name)"
+                    $0.age > 20 && $0.firstName == "\(name)"
                 })
             }
         }, rerunOnOpen: true)
@@ -698,6 +708,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
         let user = try await createUser()
         let isFirstOpen = Locked(true)
+        let name = self.name
         var config = user.flexibleSyncConfiguration(initialSubscriptions: { subscriptions in
             subscriptions.append(QuerySubscription<SwiftTypesSyncObject>(query: {
                 let date = isFirstOpen.wrappedValue ? Calendar.current.date(
@@ -708,7 +719,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
                         value: -20,
                         to: Date())
                 isFirstOpen.wrappedValue = false
-                return $0.stringCol == self.name && $0.dateCol < Date() && $0.dateCol > date!
+                return $0.stringCol == name && $0.dateCol < Date() && $0.dateCol > date!
             }))
         }, rerunOnOpen: true)
         config.objectTypes = [SwiftTypesSyncObject.self, SwiftPerson.self]
@@ -825,7 +836,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
             .subscribe(name: "8 or older")
         realm.syncSession!.suspend()
         let ex = XCTestExpectation(description: "no attempt to re-create subscription, returns immediately")
-        Task {
+        Task { @MainActor in
             _ = try await realm.objects(SwiftPerson.self)
                 .where { $0.firstName == name && $0.age >= 8 }
                 .subscribe(name: "8 or older")
@@ -875,7 +886,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
         let user = try await createUser()
         var config = user.flexibleSyncConfiguration()
         config.objectTypes = [SwiftPerson.self]
-        let realm = try await Realm(configuration: config, actor: MainActor.shared)
+        let realm = try await Realm(configuration: config)
         let results1 = try await realm.objects(SwiftPerson.self)
             .where { $0.firstName == name && $0.age > 8 }.subscribe(waitForSync: .onCreation)
         XCTAssertEqual(results1.count, 2)
@@ -890,12 +901,18 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
     @CustomGlobalActor
     func testSubscribeOnRealmConfinedCustomActor() async throws {
-        try await populateSwiftPerson()
+        nonisolated(unsafe) let unsafeSelf = self
+        try await unsafeSelf.populateSwiftPerson()
 
         let user = try await createUser()
         var config = user.flexibleSyncConfiguration()
         config.objectTypes = [SwiftPerson.self]
+#if compiler(<6)
         let realm = try await Realm(configuration: config, actor: CustomGlobalActor.shared)
+#else
+        let realm = try await Realm.open(configuration: config)
+#endif
+        let name = self.name
         let results1 = try await realm.objects(SwiftPerson.self)
             .where { $0.firstName == name && $0.age > 8 }.subscribe(waitForSync: .onCreation)
         XCTAssertEqual(results1.count, 2)
@@ -957,6 +974,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
         XCTAssertEqual(realm.subscriptions.first!.name, "sub1")
     }
 
+    @MainActor
     func testUnsubscribeNoExistingMatch() async throws {
         try await populateSwiftPerson()
         let realm = try await openRealm()
@@ -1153,6 +1171,7 @@ class AsyncFlexibleSyncTests: SwiftSyncTestCase {
 
     // MARK: - Custom Column
 
+    @MainActor
     func testCustomColumnFlexibleSyncSchema() throws {
         let realm = try openRealm()
         for property in realm.schema.objectSchema.first(where: { $0.className == "SwiftCustomColumnObject" })!.properties {