Make _NIOFileSystem strict concurrency compatible

Package.swift

@@ -247,7 +247,7 @@ let package = Package(
             path: "Sources/NIOFileSystem",
             exclude: includePrivacyManifest ? [] : ["PrivacyInfo.xcprivacy"],
             resources: includePrivacyManifest ? [.copy("PrivacyInfo.xcprivacy")] : [],
-            swiftSettings: [
+            swiftSettings: strictConcurrencySettings + [
                 .define("ENABLE_MOCKING", .when(configuration: .debug))
             ]
         ),

Sources/NIOCore/AsyncSequences/NIOAsyncSequenceProducer.swift

@@ -105,7 +105,7 @@ public struct NIOAsyncSequenceProducer<
     /// to yield new elements to the sequence.
     /// 2. The ``sequence`` which is the actual `AsyncSequence` and
     /// should be passed to the consumer.
-    public struct NewSequence {
+    public struct NewSequence: Sendable {
         /// The source of the ``NIOAsyncSequenceProducer`` used to yield and finish.
         public let source: Source
         /// The actual sequence which should be passed to the consumer.
@@ -268,7 +268,7 @@ extension NIOAsyncSequenceProducer {
         }
 
         /// The result of a call to ``NIOAsyncSequenceProducer/Source/yield(_:)``.
-        public enum YieldResult: Hashable {
+        public enum YieldResult: Hashable, Sendable {
             /// Indicates that the caller should produce more elements for now. The delegate's ``NIOAsyncSequenceProducerDelegate/produceMore()``
             /// will **NOT** get called, since the demand was already signalled through this ``NIOAsyncSequenceProducer/Source/YieldResult``.
             case produceMore

Sources/NIOFileSystem/DirectoryEntries.swift

@@ -21,7 +21,7 @@ import SystemPackage
 
 /// An `AsyncSequence` of entries in a directory.
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-public struct DirectoryEntries: AsyncSequence {
+public struct DirectoryEntries: AsyncSequence, Sendable {
     public typealias AsyncIterator = DirectoryIterator
     public typealias Element = DirectoryEntry
 
@@ -35,7 +35,8 @@ public struct DirectoryEntries: AsyncSequence {
 
     /// Creates a ``DirectoryEntries`` sequence by wrapping an `AsyncSequence` of _batches_ of
     /// directory entries.
-    public init<S: AsyncSequence>(wrapping sequence: S) where S.Element == Batched.Element {
+    @preconcurrency
+    public init<S: AsyncSequence & Sendable>(wrapping sequence: S) where S.Element == Batched.Element {
         self.batchedSequence = Batched(wrapping: sequence)
     }
 
@@ -85,15 +86,16 @@ extension DirectoryEntries {
     /// The ``Batched`` sequence uses `Array<DirectoryEntry>` as its element type rather
     /// than `DirectoryEntry`. This can enable better performance by reducing the number of
     /// executor hops at the cost of ease-of-use.
-    public struct Batched: AsyncSequence {
+    public struct Batched: AsyncSequence, Sendable {
         public typealias AsyncIterator = BatchedIterator
         public typealias Element = [DirectoryEntry]
 
         private let stream: BufferedOrAnyStream<[DirectoryEntry], DirectoryEntryProducer>
 
         /// Creates a ``DirectoryEntries/Batched`` sequence by wrapping an `AsyncSequence`
         /// of directory entry batches.
-        public init<S: AsyncSequence>(wrapping sequence: S) where S.Element == Element {
+        @preconcurrency
+        public init<S: AsyncSequence & Sendable>(wrapping sequence: S) where S.Element == Element {
             self.stream = BufferedOrAnyStream<[DirectoryEntry], DirectoryEntryProducer>(wrapping: sequence)
         }
 

Sources/NIOFileSystem/Internal/BufferedOrAnyStream.swift

@@ -16,7 +16,7 @@ import NIOCore
 
 /// Wraps a ``NIOThrowingAsyncSequenceProducer<Element>`` or ``AnyAsyncSequence<Element>``.
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-internal enum BufferedOrAnyStream<Element, Delegate: NIOAsyncSequenceProducerDelegate> {
+internal enum BufferedOrAnyStream<Element: Sendable, Delegate: NIOAsyncSequenceProducerDelegate>: Sendable {
     typealias AsyncSequenceProducer = NIOThrowingAsyncSequenceProducer<
         Element, Error, NIOAsyncSequenceProducerBackPressureStrategies.HighLowWatermark, Delegate
     >
@@ -28,7 +28,7 @@ internal enum BufferedOrAnyStream<Element, Delegate: NIOAsyncSequenceProducerDel
         self = .nioThrowingAsyncSequenceProducer(stream)
     }
 
-    internal init<S: AsyncSequence>(wrapping stream: S) where S.Element == Element {
+    internal init<S: AsyncSequence & Sendable>(wrapping stream: S) where S.Element == Element {
         self = .anyAsyncSequence(AnyAsyncSequence(wrapping: stream))
     }
 
@@ -69,10 +69,10 @@ internal enum BufferedOrAnyStream<Element, Delegate: NIOAsyncSequenceProducerDel
 }
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-internal struct AnyAsyncSequence<Element>: AsyncSequence {
-    private let _makeAsyncIterator: () -> AsyncIterator
+internal struct AnyAsyncSequence<Element>: AsyncSequence, Sendable {
+    private let _makeAsyncIterator: @Sendable () -> AsyncIterator
 
-    internal init<S: AsyncSequence>(wrapping sequence: S) where S.Element == Element {
+    internal init<S: AsyncSequence & Sendable>(wrapping sequence: S) where S.Element == Element {
         self._makeAsyncIterator = {
             AsyncIterator(wrapping: sequence.makeAsyncIterator())
         }

Sources/NIOFileSystem/Internal/BufferedStream.swift

@@ -118,7 +118,7 @@ import NIOConcurrencyHelpers
 ///     }
 ///
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-internal struct BufferedStream<Element> {
+internal struct BufferedStream<Element: Sendable> {
     final class _Backing: Sendable {
         let storage: _BackPressuredStorage
 
@@ -199,7 +199,7 @@ extension BufferedStream: AsyncSequence {
 }
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-extension BufferedStream: Sendable where Element: Sendable {}
+extension BufferedStream: Sendable {}
 
 internal struct _ManagedCriticalState<State>: @unchecked Sendable {
     let lock: NIOLockedValueBox<State>
@@ -303,7 +303,7 @@ extension BufferedStream {
         /// - Parameter sequence: The elements to write to the asynchronous stream.
         /// - Returns: The result that indicates if more elements should be produced at this time.
         internal func write<S>(contentsOf sequence: S) throws -> WriteResult
-        where Element == S.Element, S: Sequence {
+        where Element == S.Element, S: Sequence, Element: Sendable {
             try self._backing.storage.write(contentsOf: sequence)
         }
 
@@ -363,7 +363,7 @@ extension BufferedStream {
         internal func write<S>(
             contentsOf sequence: S,
             onProduceMore: @escaping @Sendable (Result<Void, Error>) -> Void
-        ) where Element == S.Element, S: Sequence {
+        ) where Element == S.Element, S: Sequence, Element: Sendable {
             do {
                 let writeResult = try self.write(contentsOf: sequence)
 
@@ -407,7 +407,7 @@ extension BufferedStream {
         /// - Parameters:
         ///   - sequence: The elements to write to the asynchronous stream.
         internal func write<S>(contentsOf sequence: S) async throws
-        where Element == S.Element, S: Sequence {
+        where Element == S.Element, S: Sequence, Element: Sendable {
             let writeResult = try { try self.write(contentsOf: sequence) }()
 
             switch writeResult {
@@ -458,7 +458,7 @@ extension BufferedStream {
         /// - Parameters:
         ///   - sequence: The elements to write to the asynchronous stream.
         internal func write<S>(contentsOf sequence: S) async throws
-        where Element == S.Element, S: AsyncSequence {
+        where Element == S.Element, S: AsyncSequence, Element: Sendable {
             for try await element in sequence {
                 try await self.write(contentsOf: CollectionOfOne(element))
             }