feat: first pass at conforming to Sendable

.circleci/config.yml

@@ -0,0 +1,42 @@
+version: 2.1
+
+## Orbs
+orbs:
+  macos: circleci/macos@2
+
+## Jobs
+jobs:
+  unit_test:
+    macos:
+      xcode: 14.0.1
+    environment:
+      HOMEBREW_NO_AUTO_UPDATE: 1
+    steps:
+      - macos/preboot-simulator:
+          version: "16.0"
+          platform: "iOS"
+          device: "iPhone 14 Pro"
+      - macos/preboot-simulator:
+          version: "15.5"
+          platform: "iOS"
+          device: "iPhone 13 Pro"
+      - checkout
+      - run: 
+          name: Install xcpretty
+          command: gem install xcpretty
+      - run: 
+          name: Run iOS16 unit tests
+          command: Scripts/test -d "OS=16.0,name=iPhone 14 Pro" | xcpretty --color --report junit --output ~/test-results/ios16-results.xml
+      - run: 
+          name: Run iOS15.5 unit tests
+          command: Scripts/test -d "OS=15.5,name=iPhone 13 Pro" | xcpretty --color --report junit --output ~/test-results/ios15-results.xml
+      - store_test_results:
+          path: ~/test-results
+      - store_artifacts:
+          path: ~/Library/Logs/DiagnosticReports
+
+## Workflows
+workflows:
+  on_push:
+    jobs:
+      - unit_test

Asynchrone.xcodeproj/project.pbxproj

@@ -413,7 +413,7 @@
 			attributes = {
 				BuildIndependentTargetsInParallel = 1;
 				LastSwiftUpdateCheck = 1310;
-				LastUpgradeCheck = 1310;
+				LastUpgradeCheck = 1400;
 				TargetAttributes = {
 					A4C361A9276A5EF200511525 = {
 						CreatedOnToolsVersion = 13.1;
@@ -599,6 +599,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_STRICT_CONCURRENCY = minimal;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -656,6 +657,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
+				SWIFT_STRICT_CONCURRENCY = minimal;
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
 			};
@@ -664,11 +666,11 @@
 		A4C361BF276A5EF200511525 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				CODE_SIGN_IDENTITY = "Apple Development";
-				"CODE_SIGN_IDENTITY[sdk=macosx*]" = "Apple Development";
+				CODE_SIGN_IDENTITY = "";
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
+				DEAD_CODE_STRIPPING = YES;
 				DEFINES_MODULE = YES;
 				DEVELOPMENT_TEAM = "";
 				DYLIB_COMPATIBILITY_VERSION = 1;
@@ -692,18 +694,19 @@
 				SKIP_INSTALL = YES;
 				SUPPORTED_PLATFORMS = "macosx iphoneos appletvos watchos iphonesimulator appletvsimulator watchsimulator appletvos";
 				SWIFT_EMIT_LOC_STRINGS = YES;
+				SWIFT_STRICT_CONCURRENCY = complete;
 				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
 		A4C361C0276A5EF200511525 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
-				CODE_SIGN_IDENTITY = "Apple Development";
-				"CODE_SIGN_IDENTITY[sdk=macosx*]" = "Apple Development";
+				CODE_SIGN_IDENTITY = "";
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
+				DEAD_CODE_STRIPPING = YES;
 				DEFINES_MODULE = YES;
 				DEVELOPMENT_TEAM = "";
 				DYLIB_COMPATIBILITY_VERSION = 1;
@@ -727,6 +730,7 @@
 				SKIP_INSTALL = YES;
 				SUPPORTED_PLATFORMS = "macosx iphoneos appletvos watchos iphonesimulator appletvsimulator watchsimulator appletvos";
 				SWIFT_EMIT_LOC_STRINGS = YES;
+				SWIFT_STRICT_CONCURRENCY = complete;
 				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
@@ -740,6 +744,7 @@
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
+				DEAD_CODE_STRIPPING = YES;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 14.5;
@@ -770,6 +775,7 @@
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
 				CURRENT_PROJECT_VERSION = 1;
+				DEAD_CODE_STRIPPING = YES;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 14.5;

Asynchrone.xcodeproj/xcshareddata/xcschemes/Asynchrone.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1310"
+   LastUpgradeVersion = "1400"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

Asynchrone/Source/Extensions/AsyncSequence+Extension.swift

@@ -1,5 +1,4 @@
 extension AsyncSequence {
-
     /// Assigns each element from an async sequence to a property on an object.
     ///
     /// ```swift
@@ -35,7 +34,7 @@ extension AsyncSequence {
     public func assign<Root>(
         to keyPath: ReferenceWritableKeyPath<Root, Element>,
         on object: Root
-    ) rethrows -> Task<Void, Error> {
+    ) rethrows -> Task<Void, Error> where Self: Sendable, Root: Sendable {
         Task {
             for try await element in self {
                 object[keyPath: keyPath] = element
@@ -121,8 +120,8 @@ extension AsyncSequence {
     @discardableResult
     public func sink(
         priority: TaskPriority? = nil,
-        receiveValue: @escaping (Element) async -> Void
-    ) -> Task<Void, Error> {
+        receiveValue: @Sendable @escaping (Element) async -> Void
+    ) -> Task<Void, Error> where Self: Sendable {
         Task(priority: priority) {
             for try await element in self {
                 await receiveValue(element)
@@ -160,9 +159,9 @@ extension AsyncSequence {
     @discardableResult
     public func sink(
         priority: TaskPriority? = nil,
-        receiveValue: @escaping (Element) async -> Void,
-        receiveCompletion: @escaping (AsyncSequenceCompletion<Error>) async -> Void
-    ) -> Task<Void, Never> {
+        receiveValue: @Sendable @escaping (Element) async -> Void,
+        receiveCompletion: @Sendable @escaping (AsyncSequenceCompletion<Error>) async -> Void
+    ) -> Task<Void, Never> where Self: Sendable {
         Task(priority: priority) {
             do {
                 for try await element in self {

Asynchrone/Source/Extensions/AsyncThrowingStream+Extension.swift

@@ -20,7 +20,7 @@ extension AsyncThrowingStream {
     public init(
         _ elementType: Element.Type = Element.self,
         bufferingPolicy limit: AsyncThrowingStream<Element, Failure>.Continuation.BufferingPolicy = .unbounded,
-        _ build: @escaping (AsyncThrowingStream<Element, Failure>.Continuation) async -> Void
+        _ build: @Sendable @escaping (AsyncThrowingStream<Element, Failure>.Continuation) async -> Void
     ) where Failure == Error {
         self = AsyncThrowingStream(elementType, bufferingPolicy: limit) { continuation in
             Task {

Asynchrone/Source/Sequences/AnyAsyncSequenceable.swift

@@ -1,45 +1,53 @@
 /// An async sequence that performs type erasure by wrapping another async sequence.
 ///
 /// If the async sequence that you wish to type erase can throw, then use `AnyThrowingAsyncSequenceable`.
-public struct AnyAsyncSequenceable<Element>: AsyncSequence {
-    private var _next: () async -> Element?
-    private var _makeAsyncIterator: () -> Self
+public struct AnyAsyncSequenceable<Element>: AsyncSequence, Sendable {
+    private var _makeAsyncIterator: @Sendable () -> Iterator
 
     // MARK: Initialization
 
     /// Creates a type erasing async sequence.
     /// - Parameters:
     ///   - sequence: The async sequence to type erase.
-    public init<T>(_ sequence: T) where T: AsyncSequence, T.Element == Element {
-        var iterator = sequence.makeAsyncIterator()
-        self._next = { try? await iterator.next() }
-        self._makeAsyncIterator = { .init(sequence) }
+    public init<T>(_ sequence: T) where T: AsyncSequence, T.Element == Element, T: Sendable {
+        self._makeAsyncIterator = { Iterator(sequence.makeAsyncIterator()) }
     }
 
     /// Creates an optional type erasing async sequence.
     /// - Parameters:
     ///   - sequence: An optional async sequence to type erase.
-    public init?<T>(_ asyncSequence: T?) where T: AsyncSequence, T.Element == Element {
+    public init?<T>(_ asyncSequence: T?) where T: AsyncSequence, T.Element == Element, T: Sendable {
         guard let asyncSequence = asyncSequence else { return nil }
         self = .init(asyncSequence)
     }
 
     // MARK: AsyncSequence
-
-    /// Creates an async iterator that emits elements of this async sequence.
-    /// - Returns: An instance that conforms to `AsyncIteratorProtocol`.
-    public func makeAsyncIterator() -> Self {
+
+    public func makeAsyncIterator() -> Iterator {
         self._makeAsyncIterator()
     }
 }
 
-// MARK: AsyncIteratorProtocol
+// MARK: Iterator
 
-extension AnyAsyncSequenceable: AsyncIteratorProtocol {
-    /// Produces the next element in the sequence.
-    /// - Returns: The next element or `nil` if the end of the sequence is reached.
-    public mutating func next() async -> Element? {
-        await self._next()
+extension AnyAsyncSequenceable {
+    public struct Iterator: AsyncIteratorProtocol {
+        private var iterator: any AsyncIteratorProtocol
+
+        // MARK: Initialization
+
+        init<T>(_ iterator: T) where T: AsyncIteratorProtocol, T.Element == Element {
+            self.iterator = iterator
+        }
+
+        // MARK: AsyncIteratorProtocol
+
+        public mutating func next() async -> Element? {
+            // NOTE: When `AsyncSequence`, `AsyncIteratorProtocol` get their Element as
+            // their primary associated type we won't need the casting.
+            // https://github.com/apple/swift-evolution/blob/main/proposals/0358-primary-associated-types-in-stdlib.md#alternatives-considered
+            try? await self.iterator.next() as? Element
+        }
     }
 }
 
@@ -51,7 +59,7 @@ extension AsyncSequence {
     /// If the async sequence that you wish to type erase can throw,
     /// then use `eraseToAnyThrowingAsyncSequenceable()`.
     /// - Returns: A typed erased async sequence.
-    public func eraseToAnyAsyncSequenceable() -> AnyAsyncSequenceable<Element> {
+    public func eraseToAnyAsyncSequenceable() -> AnyAsyncSequenceable<Element> where Self: Sendable {
         .init(self)
     }
 }

Asynchrone/Source/Sequences/AnyThrowingAsyncSequenceable.swift

@@ -1,45 +1,53 @@
 /// A throwing async sequence that performs type erasure by wrapping another throwing async sequence.
 ///
 /// If the async sequence that you wish to type erase doesn't throw, then use `AnyAsyncSequenceable`.
-public struct AnyThrowingAsyncSequenceable<Element>: AsyncSequence {
-    private var _next: () async throws -> Element?
-    private var _makeAsyncIterator: () -> Self
+public struct AnyThrowingAsyncSequenceable<Element>: AsyncSequence, Sendable {
+    private var _makeAsyncIterator: @Sendable () -> Iterator
 
     // MARK: Initialization
-
+    
     /// Creates a type erasing async sequence.
     /// - Parameters:
     ///   - sequence: The async sequence to type erase.
-    public init<T>(_ asyncSequence: T) where T: AsyncSequence, T.Element == Element {
-        var iterator = asyncSequence.makeAsyncIterator()
-        self._next = { try await iterator.next() }
-        self._makeAsyncIterator = { .init(asyncSequence) }
+    public init<T>(_ sequence: T) where T: AsyncSequence, T: Sendable, T.Element == Element {
+        self._makeAsyncIterator = { Iterator(sequence.makeAsyncIterator()) }
     }
 
     /// Creates an optional type erasing async sequence.
     /// - Parameters:
     ///   - sequence: An optional async sequence to type erase.
-    public init?<T>(_ asyncSequence: T?) where T: AsyncSequence, T.Element == Element {
+    public init?<T>(_ asyncSequence: T?) where T: AsyncSequence, T: Sendable, T.Element == Element {
         guard let asyncSequence = asyncSequence else { return nil }
         self = .init(asyncSequence)
     }
 
     // MARK: AsyncSequence
-
-    /// Creates an async iterator that emits elements of this async sequence.
-    /// - Returns: An instance that conforms to `AsyncIteratorProtocol`.
-    public func makeAsyncIterator() -> Self {
+
+    public func makeAsyncIterator() -> Iterator {
         self._makeAsyncIterator()
     }
 }
 
-// MARK: AsyncIteratorProtocol
+// MARK: Iterator
 
-extension AnyThrowingAsyncSequenceable: AsyncIteratorProtocol {
-    /// Produces the next element in the sequence.
-    /// - Returns: The next element or `nil` if the end of the sequence is reached.
-    public mutating func next() async throws -> Element? {
-        try await self._next()
+extension AnyThrowingAsyncSequenceable {
+    public struct Iterator: AsyncIteratorProtocol {
+        private var iterator: any AsyncIteratorProtocol
+
+        // MARK: Initialization
+
+        init<T>(_ iterator: T) where T: AsyncIteratorProtocol, T.Element == Element {
+            self.iterator = iterator
+        }
+
+        // MARK: AsyncIteratorProtocol
+
+        public mutating func next() async throws -> Element? {
+            // NOTE: When `AsyncSequence`, `AsyncIteratorProtocol` get their Element as
+            // their primary associated type we won't need the casting.
+            // https://github.com/apple/swift-evolution/blob/main/proposals/0358-primary-associated-types-in-stdlib.md#alternatives-considered
+            try await self.iterator.next() as? Element
+        }
     }
 }
 
@@ -52,7 +60,7 @@ extension AsyncSequence {
     /// If the async sequence that you wish to type erase deson't throw,
     /// then use `eraseToAnyAsyncSequenceable()`.
     /// - Returns: A typed erased async sequence.
-    public func eraseToAnyThrowingAsyncSequenceable() -> AnyThrowingAsyncSequenceable<Element> {
+    public func eraseToAnyThrowingAsyncSequenceable() -> AnyThrowingAsyncSequenceable<Element> where Self: Sendable {
         .init(self)
     }
 }