Fix a few sendability warnings in core. (#159)

Package@swift-5.9.swift

@@ -0,0 +1,63 @@
+// swift-tools-version:5.9
+
+import PackageDescription
+
+let package = Package(
+  name: "swiftui-navigation",
+  platforms: [
+    .iOS(.v13),
+    .macOS(.v10_15),
+    .tvOS(.v13),
+    .watchOS(.v6),
+  ],
+  products: [
+    .library(
+      name: "SwiftUINavigation",
+      targets: ["SwiftUINavigation"]
+    ),
+    .library(
+      name: "SwiftUINavigationCore",
+      targets: ["SwiftUINavigationCore"]
+    ),
+  ],
+  dependencies: [
+    .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.0.0"),
+    .package(url: "https://github.com/pointfreeco/swift-case-paths", from: "1.2.2"),
+    .package(url: "https://github.com/pointfreeco/swift-custom-dump", from: "1.0.0"),
+    .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "1.0.0"),
+  ],
+  targets: [
+    .target(
+      name: "SwiftUINavigation",
+      dependencies: [
+        "SwiftUINavigationCore",
+        .product(name: "CasePaths", package: "swift-case-paths"),
+      ]
+    ),
+    .testTarget(
+      name: "SwiftUINavigationTests",
+      dependencies: [
+        "SwiftUINavigation"
+      ]
+    ),
+    .target(
+      name: "SwiftUINavigationCore",
+      dependencies: [
+        .product(name: "CustomDump", package: "swift-custom-dump"),
+        .product(name: "XCTestDynamicOverlay", package: "xctest-dynamic-overlay"),
+      ]
+    ),
+  ]
+)
+
+for target in package.targets {
+  target.swiftSettings = target.swiftSettings ?? []
+  target.swiftSettings!.append(contentsOf: [
+    .enableExperimentalFeature("StrictConcurrency")
+  ])
+  // target.swiftSettings?.append(
+  //   .unsafeFlags([
+  //     "-enable-library-evolution",
+  //   ])
+  // )
+}

Sources/SwiftUINavigation/Alert.swift

@@ -46,9 +46,9 @@
     ///     dismisses the alert, and the action is fed to the `action` closure.
     ///   - handler: A closure that is called with an action from a particular alert button when
     ///     tapped.
-    public func alert<Value>(
+    public func alert<Value: Sendable>(
       _ state: Binding<AlertState<Value>?>,
-      action handler: @escaping (Value?) async -> Void = { (_: Never?) async in }
+      action handler: @escaping @Sendable (Value?) async -> Void = { (_: Never?) async in }
     ) -> some View {
       alert(item: state) {
         Text($0.title)

Sources/SwiftUINavigation/ConfirmationDialog.swift

@@ -49,9 +49,9 @@
     ///   - handler: A closure that is called with an action from a particular dialog button when
     ///     tapped.
     @available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
-    public func confirmationDialog<Value>(
+    public func confirmationDialog<Value: Sendable>(
       _ state: Binding<ConfirmationDialogState<Value>?>,
-      action handler: @escaping (Value?) async -> Void = { (_: Never?) async in }
+      action handler: @escaping @Sendable (Value?) async -> Void = { (_: Never?) async in }
     ) -> some View {
       confirmationDialog(
         item: state,

Sources/SwiftUINavigationCore/AlertState.swift

@@ -249,7 +249,10 @@
     ///   - state: Alert state used to populate the alert.
     ///   - action: An action handler, called when a button with an action is tapped, by passing the
     ///     action to the closure.
-    public init<Action>(_ state: AlertState<Action>, action: @escaping (Action?) async -> Void) {
+    public init<Action: Sendable>(
+      _ state: AlertState<Action>,
+      action: @escaping @Sendable (Action?) async -> Void
+    ) {
       if state.buttons.count == 2 {
         self.init(
           title: Text(state.title),

Sources/SwiftUINavigationCore/ButtonState.swift

@@ -260,7 +260,10 @@
     /// - Parameters:
     ///   - button: Button state.
     ///   - action: An action closure that is invoked when the button is tapped.
-    public init<Action>(_ button: ButtonState<Action>, action: @escaping (Action?) async -> Void) {
+    public init<Action: Sendable>(
+      _ button: ButtonState<Action>,
+      action: @escaping @Sendable (Action?) async -> Void
+    ) {
       let action = { _ = Task { await button.withAction(action) } }
       switch button.role {
       case .cancel:
@@ -310,7 +313,10 @@
     ///   - button: Button state.
     ///   - action: An action closure that is invoked when the button is tapped.
     @available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
-    public init<Action>(_ button: ButtonState<Action>, action: @escaping (Action?) async -> Void) {
+    public init<Action: Sendable>(
+      _ button: ButtonState<Action>,
+      action: @escaping @Sendable (Action?) async -> Void
+    ) {
       self.init(
         role: button.role.map(ButtonRole.init),
         action: { Task { await button.withAction(action) } }