Remove platforms from manifest (#203)

Motivation:

Adding or raising the deployment platforms in the package manifest is a
SemVer major breaking change as consumers must also add or raise their
deployment platforms. This is a known limitation of SwiftPM.

Unforunately this means that it's very difficult for non-leaf packages
to adopt packages which declare their platforms in the manifest. Doing
so puts the brakes on adoption and ecosystem growth. For 'core' packages
like this one availability constraints should be expressed on
declarations rather than in the manifest.

Modifications:

- Remove platforms from the package manifest
- Add availability annotations to types which require it

Result:

This package can be more widely adopted

Author: glbrntt

Package.swift

@@ -3,12 +3,6 @@ import PackageDescription
 
 let package = Package(
     name: "swift-service-lifecycle",
-    platforms: [
-        .macOS(.v10_15),
-        .iOS(.v13),
-        .watchOS(.v6),
-        .tvOS(.v13),
-    ],
     products: [
         .library(
             name: "ServiceLifecycle",
@@ -30,7 +24,7 @@ let package = Package(
         ),
         .package(
             url: "https://github.com/apple/swift-async-algorithms.git",
-            from: "1.0.0"
+            from: "1.0.4"
         ),
     ],
     targets: [

Sources/ServiceLifecycle/AsyncCancelOnGracefulShutdownSequence.swift

@@ -14,6 +14,7 @@
 
 import AsyncAlgorithms
 
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension AsyncSequence where Self: Sendable, Element: Sendable {
     /// Creates an asynchronous sequence that is cancelled once graceful shutdown has triggered.
     ///
@@ -24,6 +25,7 @@ extension AsyncSequence where Self: Sendable, Element: Sendable {
 }
 
 /// An asynchronous sequence that is cancelled once graceful shutdown has triggered.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public struct AsyncCancelOnGracefulShutdownSequence<Base: AsyncSequence & Sendable>: AsyncSequence, Sendable
 where Base.Element: Sendable {
     @usableFromInline
@@ -101,6 +103,7 @@ where Base.Element: Sendable {
 /// This is just a helper extension and sequence to allow us to get the `nil` value as an element of the sequence.
 /// We need this since merge is only finishing when both upstreams are finished but we need to finish when either is done.
 /// In the future, we should move to something in async algorithms if it exists.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension AsyncSequence where Self: Sendable, Element: Sendable {
     @inlinable
     func mapNil() -> AsyncMapNilSequence<Self> {
@@ -109,6 +112,7 @@ extension AsyncSequence where Self: Sendable, Element: Sendable {
 }
 
 @usableFromInline
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 struct AsyncMapNilSequence<Base: AsyncSequence & Sendable>: AsyncSequence, Sendable where Base.Element: Sendable {
     @usableFromInline
     enum ElementOrEnd: Sendable {

Sources/ServiceLifecycle/AsyncGracefulShutdownSequence.swift

@@ -18,6 +18,7 @@
 ///
 /// - Note: This sequence respects cancellation and thus is `throwing`.
 @usableFromInline
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 struct AsyncGracefulShutdownSequence: AsyncSequence, Sendable {
     @usableFromInline
     typealias Element = CancellationWaiter.Reason

Sources/ServiceLifecycle/CancellationWaiter.swift

@@ -14,6 +14,7 @@
 
 /// An actor that provides a function to wait on cancellation/graceful shutdown.
 @usableFromInline
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 actor CancellationWaiter {
     @usableFromInline
     enum Reason: Sendable {

Sources/ServiceLifecycle/GracefulShutdown.swift

@@ -37,6 +37,7 @@ import ConcurrencyHelpers
 ///   - handler: The handler which is invoked once graceful shutdown has been triggered.
 // Unsafely inheriting the executor is safe to do here since we are not calling any other async method
 // except the operation. This makes sure no other executor hops would occur here.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func withGracefulShutdownHandler<T>(
     isolation: isolated (any Actor)? = #isolation,
     operation: () async throws -> T,
@@ -58,6 +59,7 @@ public func withGracefulShutdownHandler<T>(
 }
 
 @available(*, deprecated, message: "Use the method with the isolation parameter instead.")
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 @_disfavoredOverload
 public func withGracefulShutdownHandler<T>(
     operation: () async throws -> T,
@@ -83,6 +85,7 @@ public func withGracefulShutdownHandler<T>(
 // Swift versions since the semantics changed.
 @_disfavoredOverload
 @_unsafeInheritExecutor
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func withGracefulShutdownHandler<T>(
     operation: () async throws -> T,
     onGracefulShutdown handler: @Sendable @escaping () -> Void
@@ -127,6 +130,7 @@ public func withGracefulShutdownHandler<T>(
 ///   - handler: The handler which is invoked once graceful shutdown or task cancellation has been triggered.
 // Unsafely inheriting the executor is safe to do here since we are not calling any other async method
 // except the operation. This makes sure no other executor hops would occur here.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func withTaskCancellationOrGracefulShutdownHandler<T>(
     isolation: isolated (any Actor)? = #isolation,
     operation: () async throws -> T,
@@ -139,6 +143,7 @@ public func withTaskCancellationOrGracefulShutdownHandler<T>(
     }
 }
 @available(*, deprecated, message: "Use the method with the isolation parameter instead.")
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 @_disfavoredOverload
 public func withTaskCancellationOrGracefulShutdownHandler<T>(
     operation: () async throws -> T,
@@ -152,6 +157,7 @@ public func withTaskCancellationOrGracefulShutdownHandler<T>(
 }
 #else
 @available(*, deprecated, message: "Use the method with the isolation parameter instead.")
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 @_disfavoredOverload
 @_unsafeInheritExecutor
 public func withTaskCancellationOrGracefulShutdownHandler<T>(
@@ -172,6 +178,7 @@ public func withTaskCancellationOrGracefulShutdownHandler<T>(
 /// graceful shutdown is triggered then this method will throw a `CancellationError`.
 ///
 /// - Throws: `CancellationError` if the task is cancelled.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func gracefulShutdown() async throws {
     switch await AsyncGracefulShutdownSequence().first(where: { _ in true }) {
     case .cancelled:
@@ -193,6 +200,7 @@ enum ValueOrGracefulShutdown<T: Sendable>: Sendable {
 /// Cancels the closure when a graceful shutdown was triggered.
 ///
 /// - Parameter operation: The actual operation.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func cancelWhenGracefulShutdown<T: Sendable>(
     _ operation: @Sendable @escaping () async throws -> T
 ) async rethrows -> T {
@@ -243,12 +251,14 @@ public func cancelWhenGracefulShutdown<T: Sendable>(
 // renamed pattern has been shown to cause compiler crashes in 5.x compilers.
 @available(*, deprecated, message: "renamed to cancelWhenGracefulShutdown")
 #endif
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func cancelOnGracefulShutdown<T: Sendable>(
     _ operation: @Sendable @escaping () async throws -> T
 ) async rethrows -> T? {
     return try await cancelWhenGracefulShutdown(operation)
 }
 
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Task where Success == Never, Failure == Never {
     /// A Boolean value that indicates whether the task is gracefully shutting down
     ///
@@ -263,13 +273,15 @@ extension Task where Success == Never, Failure == Never {
 }
 
 @_spi(TestKit)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public enum TaskLocals {
     @TaskLocal
     @_spi(TestKit)
     public static var gracefulShutdownManager: GracefulShutdownManager?
 }
 
 @_spi(TestKit)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public final class GracefulShutdownManager: @unchecked Sendable {
     struct Handler {
         /// The id of the handler.

Sources/ServiceLifecycle/Service.swift

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 /// This is the basic protocol that a service has to implement.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public protocol Service: Sendable {
     /// This method is called when the ``ServiceGroup`` is starting all the services.
     ///

Sources/ServiceLifecycle/ServiceGroup.swift

@@ -17,6 +17,7 @@ import UnixSignals
 import AsyncAlgorithms
 
 /// A ``ServiceGroup`` is responsible for running a number of services, setting up signal handling and signalling graceful shutdown to the services.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public actor ServiceGroup: Sendable, Service {
     /// The internal state of the ``ServiceGroup``.
     private enum State {
@@ -893,6 +894,7 @@ public actor ServiceGroup: Sendable, Service {
 }
 
 // This should be removed once we support Swift 5.9+
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension AsyncStream {
     fileprivate static func makeStream(
         of elementType: Element.Type = Element.self,

Sources/ServiceLifecycle/ServiceGroupConfiguration.swift

@@ -18,6 +18,7 @@ import UnixSignals
 let deprecatedLoggerLabel = "service-lifecycle-deprecated-method-logger"
 
 /// The configuration for the ``ServiceGroup``.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public struct ServiceGroupConfiguration: Sendable {
     /// The group's logging configuration.
     public struct LoggingConfiguration: Sendable {

Sources/ServiceLifecycleTestKit/GracefulShutdown.swift

@@ -18,6 +18,7 @@
 ///
 /// It is passed to the `operation` closure of the ``testGracefulShutdown(operation:)`` method and allows
 /// to trigger the graceful shutdown for testing purposes.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public struct GracefulShutdownTestTrigger: Sendable {
     private let gracefulShutdownManager: GracefulShutdownManager
 
@@ -35,6 +36,7 @@ public struct GracefulShutdownTestTrigger: Sendable {
 ///
 /// Call the code that you want to test inside the `operation` closure and trigger the graceful shutdown by calling ``GracefulShutdownTestTrigger/triggerGracefulShutdown()``
 /// on the ``GracefulShutdownTestTrigger`` that is passed to the `operation` closure.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public func testGracefulShutdown<T>(operation: (GracefulShutdownTestTrigger) async throws -> T) async rethrows -> T {
     let gracefulShutdownManager = GracefulShutdownManager()
     return try await TaskLocals.$gracefulShutdownManager.withValue(gracefulShutdownManager) {

Sources/UnixSignals/UnixSignalsSequence.swift

@@ -33,6 +33,7 @@ import ConcurrencyHelpers
 ///
 /// - Important: There can only be a single signal handler for a signal installed. So you should avoid creating multiple handlers
 /// for the same signal.
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 public struct UnixSignalsSequence: AsyncSequence, Sendable {
     private static let queue = DispatchQueue(label: "com.service-lifecycle.unix-signals")
 
@@ -74,6 +75,7 @@ public struct UnixSignalsSequence: AsyncSequence, Sendable {
     }
 }
 
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension UnixSignalsSequence {
     fileprivate final class Storage: @unchecked Sendable {
         private let stateMachine: LockedValueBox<StateMachine>
@@ -169,6 +171,7 @@ extension UnixSignalsSequence {
     }
 }
 
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension UnixSignalsSequence {
     fileprivate struct StateMachine {
         private enum State {

Tests/ServiceLifecycleTests/GracefulShutdownTests.swift

@@ -16,6 +16,7 @@ import ServiceLifecycle
 import ServiceLifecycleTestKit
 import XCTest
 
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 final class GracefulShutdownTests: XCTestCase {
     func testWithGracefulShutdownHandler() async {
         var cont: AsyncStream<Void>.Continuation!
@@ -255,6 +256,7 @@ final class GracefulShutdownTests: XCTestCase {
         }
     }
 
+    @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
     func testWaitForGracefulShutdown() async throws {
         try await testGracefulShutdown { gracefulShutdownTestTrigger in
             try await withThrowingTaskGroup(of: Void.self) { group in
@@ -274,6 +276,7 @@ final class GracefulShutdownTests: XCTestCase {
         }
     }
 
+    @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
     func testWaitForGracefulShutdown_WhenAlreadyShutdown() async throws {
         try await testGracefulShutdown { gracefulShutdownTestTrigger in
             gracefulShutdownTestTrigger.triggerGracefulShutdown()
@@ -355,6 +358,7 @@ final class GracefulShutdownTests: XCTestCase {
         }
     }
 
+    @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
     func testCancelWhenGracefulShutdownSurvivesCancellation() async throws {
         await withTaskGroup(of: Void.self) { group in
             group.addTask {
@@ -375,6 +379,7 @@ final class GracefulShutdownTests: XCTestCase {
         }
     }
 
+    @available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
     func testCancelWhenGracefulShutdownSurvivesErrorThrown() async throws {
         struct MyError: Error, Equatable {}