Add Sendable conformances (pointfreeco#120)

* Add `Sendable` conformances

SwiftUI only annotated some of the types that are used in this package
with Xcode 15 / Swift 5.9, so we need to guard conformances only when
compiling with Swift 5.9 or higher.

Thanks @rowjo for starting this work in
https://github.com/pointfreeco/swiftui-navigation/pull/116.

* Small fixes.

---------

Co-authored-by: Brandon Williams <[email protected]>

Author: jpsim

Sources/SwiftUINavigationCore/ButtonState.swift

@@ -147,7 +147,7 @@ public struct ButtonStateAction<Action> {
 /// A value that describes the purpose of a button.
 ///
 /// See `SwiftUI.ButtonRole` for more information.
-public enum ButtonStateRole {
+public enum ButtonStateRole: Sendable {
   /// A role that indicates a cancel button.
   ///
   /// See `SwiftUI.ButtonRole.cancel` for more information.
@@ -227,6 +227,12 @@ extension ButtonState: Hashable where Action: Hashable {
   }
 }
 
+#if swift(>=5.7)
+extension ButtonStateAction: Sendable where Action: Sendable {}
+extension ButtonStateAction._ActionType: Sendable where Action: Sendable {}
+extension ButtonState: Sendable where Action: Sendable {}
+#endif
+
 // MARK: - SwiftUI bridging
 
 extension Alert.Button {

Sources/SwiftUINavigationCore/ConfirmationDialogState.swift

@@ -199,7 +199,7 @@ public struct ConfirmationDialogState<Action>: Identifiable {
 /// platform, current context, and other factors.
 ///
 /// See `SwiftUI.Visibility` for more information.
-public enum ConfirmationDialogStateTitleVisibility {
+public enum ConfirmationDialogStateTitleVisibility: Sendable {
   /// The element may be visible or hidden depending on the policies of the component accepting the
   /// visibility configuration.
   ///
@@ -265,6 +265,14 @@ extension ConfirmationDialogState: Hashable where Action: Hashable {
   }
 }
 
+#if swift(>=5.7)
+@available(iOS 13, *)
+@available(macOS 12, *)
+@available(tvOS 13, *)
+@available(watchOS 6, *)
+extension ConfirmationDialogState: Sendable where Action: Sendable {}
+#endif
+
 // MARK: - SwiftUI bridging
 
 @available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)

Sources/SwiftUINavigationCore/TextState.swift

@@ -43,11 +43,11 @@ import SwiftUI
 /// - Note: ``TextState`` does not support _all_ `LocalizedStringKey` permutations at this time
 ///   (interpolated `SwiftUI.Image`s, for example). ``TextState`` also uses reflection to determine
 ///   `LocalizedStringKey` equatability, so be mindful of edge cases.
-public struct TextState: Equatable, Hashable {
+public struct TextState: Equatable, Hashable, Sendable {
   fileprivate var modifiers: [Modifier] = []
   fileprivate let storage: Storage
 
-  fileprivate enum Modifier: Equatable, Hashable {
+  fileprivate enum Modifier: Equatable, Hashable, Sendable {
     case accessibilityHeading(AccessibilityHeadingLevel)
     case accessibilityLabel(TextState)
     case accessibilityTextContentType(AccessibilityTextContentType)
@@ -70,7 +70,7 @@ public struct TextState: Equatable, Hashable {
     case underline(isActive: Bool, pattern: LineStylePattern?, color: Color?)
   }
 
-  public enum FontWidth: String, Equatable, Hashable {
+  public enum FontWidth: String, Equatable, Hashable, Sendable {
     case compressed
     case condensed
     case expanded
@@ -89,7 +89,7 @@ public struct TextState: Equatable, Hashable {
     #endif
   }
 
-  public enum LineStylePattern: String, Equatable, Hashable {
+  public enum LineStylePattern: String, Equatable, Hashable, Sendable {
     case dash
     case dashDot
     case dashDotDot
@@ -108,7 +108,9 @@ public struct TextState: Equatable, Hashable {
     }
   }
 
-  fileprivate enum Storage: Equatable, Hashable {
+  // NB: LocalizedStringKey is documented as being Sendable, but its conformance appears to be
+  //     unavailable.
+  fileprivate enum Storage: Equatable, Hashable, @unchecked Sendable {
     indirect case concatenated(TextState, TextState)
     case localized(LocalizedStringKey, tableName: String?, bundle: Bundle?, comment: StaticString?)
     case verbatim(String)
@@ -305,7 +307,7 @@ extension TextState {
 // MARK: Accessibility
 
 extension TextState {
-  public enum AccessibilityTextContentType: String, Equatable, Hashable {
+  public enum AccessibilityTextContentType: String, Equatable, Hashable, Sendable {
     case console, fileSystem, messaging, narrative, plain, sourceCode, spreadsheet, wordProcessing
 
     #if compiler(>=5.5.1)
@@ -325,7 +327,7 @@ extension TextState {
     #endif
   }
 
-  public enum AccessibilityHeadingLevel: String, Equatable, Hashable {
+  public enum AccessibilityHeadingLevel: String, Equatable, Hashable, Sendable {
     case h1, h2, h3, h4, h5, h6, unspecified
 
     #if compiler(>=5.5.1)