feat: first pass at conforming to Sendable

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 = targeted;
 				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 = targeted;
 				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/Sequences/CatchErrorAsyncSequence.swift

@@ -16,7 +16,8 @@
 /// // Prints:
 /// // -1
 /// ```
-public struct CatchErrorAsyncSequence<Base, NewAsyncSequence>: AsyncSequence where
+public struct CatchErrorAsyncSequence<Base, NewAsyncSequence>: AsyncSequence
+where
 Base: AsyncSequence,
 NewAsyncSequence: AsyncSequence,
 Base.Element == NewAsyncSequence.Element {
@@ -25,7 +26,7 @@ Base.Element == NewAsyncSequence.Element {
 
     // Private
     private let base: Base
-    private let handler: (Error) -> NewAsyncSequence
+    private let handler: @Sendable (Error) -> NewAsyncSequence
     private var iterator: Base.AsyncIterator
     private var caughtIterator: NewAsyncSequence.AsyncIterator?
 
@@ -37,7 +38,7 @@ Base.Element == NewAsyncSequence.Element {
     ///   - output: The element with which to replace errors from the base async sequence.
     public init(
         base: Base,
-        handler: @escaping (Error) -> NewAsyncSequence
+        handler: @Sendable @escaping (Error) -> NewAsyncSequence
     ) {
         self.base = base
         self.handler = handler
@@ -53,6 +54,9 @@ Base.Element == NewAsyncSequence.Element {
     }
 }
 
+extension CatchErrorAsyncSequence: Sendable
+where Base: Sendable, NewAsyncSequence: Sendable, Base.AsyncIterator: Sendable, NewAsyncSequence.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension CatchErrorAsyncSequence: AsyncIteratorProtocol {
@@ -95,7 +99,7 @@ extension AsyncSequence {
     /// - Parameter handler: A closure that takes an Error and returns a new async sequence.
     /// - Returns: A `CatchErrorAsyncSequence` instance.
     public func `catch`<S>(
-        _ handler: @escaping (Error) -> S
+        _ handler: @Sendable @escaping (Error) -> S
     ) -> CatchErrorAsyncSequence<Self, S> where S: AsyncSequence, S.Element == Self.Element {
         .init(base: self, handler: handler)
     }

Asynchrone/Source/Sequences/ChainAsyncSequenceable.swift

@@ -77,6 +77,13 @@ public struct ChainAsyncSequence<P: AsyncSequence, Q: AsyncSequence>: AsyncSeque
     }
 }
 
+extension ChainAsyncSequence: Sendable
+where
+P: Sendable,
+P.AsyncIterator: Sendable,
+Q: Sendable,
+Q.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension ChainAsyncSequence: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/CombineLatest3AsyncSequence.swift

@@ -89,6 +89,18 @@ public struct CombineLatest3AsyncSequence<P: AsyncSequence, Q: AsyncSequence, R:
     }
 }
 
+extension CombineLatest3AsyncSequence: Sendable
+where
+P: Sendable,
+P.Element: Sendable,
+P.AsyncIterator: Sendable,
+Q: Sendable,
+Q.Element: Sendable,
+Q.AsyncIterator: Sendable,
+R: Sendable,
+R.Element: Sendable,
+R.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension CombineLatest3AsyncSequence: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/CombineLatestAsyncSequence.swift

@@ -75,6 +75,15 @@ public struct CombineLatestAsyncSequence<P: AsyncSequence, Q: AsyncSequence>: As
     }
 }
 
+extension CombineLatestAsyncSequence: Sendable
+where
+P: Sendable,
+P.Element: Sendable,
+P.AsyncIterator: Sendable,
+Q: Sendable,
+Q.Element: Sendable,
+Q.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension CombineLatestAsyncSequence: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/CurrentElementAsyncSequence.swift

@@ -74,8 +74,6 @@ public actor CurrentElementAsyncSequence<Element>: AsyncSequence {
 // MARK: Stream
 
 fileprivate struct _Stream<Element>: AsyncSequence {
-
-    // Private
     private var stream: AsyncStream<Element>!
     private var continuation: AsyncStream<Element>.Continuation!
 

Asynchrone/Source/Sequences/DebounceAsyncSequence.swift

@@ -32,7 +32,9 @@ import Foundation
 /// // 1
 /// // 5
 /// ```
-public struct DebounceAsyncSequence<T: AsyncSequence>: AsyncSequence {
+public struct DebounceAsyncSequence<T: AsyncSequence>: AsyncSequence
+where
+T.AsyncIterator: Sendable {
     /// The kind of elements streamed.
     public typealias Element = T.Element
 
@@ -63,6 +65,10 @@ public struct DebounceAsyncSequence<T: AsyncSequence>: AsyncSequence {
     }
 }
 
+extension DebounceAsyncSequence: Sendable
+where
+T: Sendable {}
+
 // MARK: Iterator
 
 extension DebounceAsyncSequence {
@@ -156,6 +162,10 @@ extension DebounceAsyncSequence {
     }
 }
 
+extension DebounceAsyncSequence.Iterator: Sendable
+where
+T.AsyncIterator: Sendable {}
+
 // MARK: Race result
 
 extension DebounceAsyncSequence.Iterator {
@@ -167,7 +177,7 @@ extension DebounceAsyncSequence.Iterator {
 
 // MARK: Task race coordinator
 
-fileprivate actor TaskRaceCoodinator<Success, Failure: Error>  {
+fileprivate actor TaskRaceCoodinator<Success, Failure: Error> where Success: Sendable  {
     private var winner: Task<Success, Failure>?
 
     func isFirstToCrossLine(_ task: Task<Success, Failure>) -> Bool {

Asynchrone/Source/Sequences/DelayAsyncSequence.swift

@@ -54,6 +54,11 @@ public struct DelayAsyncSequence<T: AsyncSequence>: AsyncSequence {
     }
 }
 
+extension DelayAsyncSequence: Sendable
+where
+T: Sendable,
+T.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension DelayAsyncSequence: AsyncIteratorProtocol {
@@ -73,7 +78,6 @@ extension DelayAsyncSequence: AsyncIteratorProtocol {
 // MARK: Delay
 
 extension AsyncSequence {
-
     /// Delays emission of all elements by the provided interval.
     ///
     /// ```swift

Asynchrone/Source/Sequences/Just.swift

@@ -32,6 +32,8 @@ public struct Just<Element>: AsyncSequence {
     }
 }
 
+extension Just: Sendable where Element: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension Just: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/Merge3AsyncSequence.swift

@@ -29,15 +29,14 @@
 /// // 3
 /// // 4
 /// ```
-public struct Merge3AsyncSequence<T: AsyncSequence>: AsyncSequence {
+public struct Merge3AsyncSequence<T: AsyncSequence>: AsyncSequence
+where T: Sendable, T.AsyncIterator: Sendable, T.Element: Sendable {
     /// The kind of elements streamed.
     public typealias Element = T.Element
 
     // Private
-    // swiftlint:disable implicitly_unwrapped_optional
     private var stream: AsyncThrowingStream<Element, Error>!
     private var iterator: AsyncThrowingStream<Element, Error>.Iterator!
-    // swiftlint:enable implicitly_unwrapped_optional
 
     // MARK: Initialization
 
@@ -60,7 +59,7 @@ public struct Merge3AsyncSequence<T: AsyncSequence>: AsyncSequence {
         _ r: T
     ) -> AsyncThrowingStream<Element, Error> {
         .init { continuation in
-            let handler: (
+            let handler: @Sendable (
                 _ sequence: T,
                 _ continuation: AsyncThrowingStream<Element, Error>.Continuation
             ) async throws -> Void = { sequence, continuation in

Asynchrone/Source/Sequences/MergeAsyncSequence.swift

@@ -35,15 +35,14 @@
 /// // 8
 /// // 9
 /// ```
-public struct MergeAsyncSequence<T: AsyncSequence>: AsyncSequence {
+public struct MergeAsyncSequence<T: AsyncSequence>: AsyncSequence
+where T: Sendable, T.Element: Sendable {
     /// The kind of elements streamed.
     public typealias Element = T.Element
 
     // Private
-    // swiftlint:disable implicitly_unwrapped_optional
     private var stream: AsyncStream<Element>!
     private var iterator: AsyncStream<Element>.Iterator!
-    // swiftlint:enable implicitly_unwrapped_optional
 
     // MARK: Initialization
 
@@ -64,7 +63,7 @@ public struct MergeAsyncSequence<T: AsyncSequence>: AsyncSequence {
         _ q: T
     ) -> AsyncStream<Element> {
         .init { continuation in
-            let handler: (
+            let handler: @Sendable (
                 _ sequence: T,
                 _ continuation: AsyncStream<Element>.Continuation
             ) async throws -> Void = { sequence, continuation in
@@ -107,12 +106,9 @@ extension MergeAsyncSequence: AsyncIteratorProtocol {
     }
 }
 
-
-
 // MARK: Merge
 
 extension AsyncSequence {
-
     /// An asynchronous sequence that merges two async sequence.
     ///
     /// The sequences are iterated through in parallel.

Asynchrone/Source/Sequences/RemoveDuplicatesAsyncSequence.swift

@@ -24,7 +24,7 @@ public struct RemoveDuplicatesAsyncSequence<Base: AsyncSequence>: AsyncSequence
     public typealias Element = Base.Element
 
     // A predicate closure for evaluating whether two elements are duplicates.
-    public typealias Predicate = (_ previous: Base.Element, _ current: Base.Element) -> Bool
+    public typealias Predicate = @Sendable (_ previous: Base.Element, _ current: Base.Element) -> Bool
 
     // Private
     private let base: Base
@@ -57,6 +57,12 @@ public struct RemoveDuplicatesAsyncSequence<Base: AsyncSequence>: AsyncSequence
     }
 }
 
+extension RemoveDuplicatesAsyncSequence: Sendable
+where
+Base: Sendable,
+Base.AsyncIterator: Sendable,
+Base.Element: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension RemoveDuplicatesAsyncSequence: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/ReplaceErrorAsyncSequence.swift

@@ -43,6 +43,12 @@ public struct ReplaceErrorAsyncSequence<Base: AsyncSequence>: AsyncSequence {
     }
 }
 
+extension ReplaceErrorAsyncSequence: Sendable
+where
+Base: Sendable,
+Base.Element: Sendable,
+Base.AsyncIterator: Sendable {}
+
 // MARK: AsyncIteratorProtocol
 
 extension ReplaceErrorAsyncSequence: AsyncIteratorProtocol {

Asynchrone/Source/Sequences/SequenceAsyncSequence.swift

@@ -1,6 +1,5 @@
 import Foundation
 
-
 /// An async version of `Sequence`. Generally used to turn any `Sequence` into
 /// it's async counterpart.
 ///
@@ -41,6 +40,8 @@ public struct SequenceAsyncSequence<P: Sequence>: AsyncSequence {
     }
 }
 
+extension SequenceAsyncSequence: Sendable where P: Sendable {}
+
 // MARK: SequenceAsyncSequenceIterator
 
 public struct SequenceAsyncSequenceIterator<P: Sequence>: AsyncIteratorProtocol {