More support for Swift 6. (pointfreeco#31)

Author: mbrandonw

[email protected]

@@ -26,7 +26,8 @@ let package = Package(
         "ConcurrencyExtras"
       ]
     ),
-  ]
+  ],
+  swiftLanguageVersions: [.v6]
 )
 
 #if !os(Windows)

Sources/ConcurrencyExtras/AsyncStream.swift

@@ -52,16 +52,16 @@ extension AsyncStream {
   /// ```
   ///
   /// - Parameter sequence: An async sequence.
-  public init<S: AsyncSequence>(_ sequence: S) where S.Element == Element {
+  public init<S: AsyncSequence>(_ sequence: S) where S.Element == Element, S: Sendable {
     let lock = NSLock()
-    var iterator: S.AsyncIterator?
+    let iterator = UncheckedBox<S.AsyncIterator?>(wrappedValue: nil)
     self.init {
       lock.withLock {
-        if iterator == nil {
-          iterator = sequence.makeAsyncIterator()
+        if iterator.wrappedValue == nil {
+          iterator.wrappedValue = sequence.makeAsyncIterator()
         }
       }
-      return try? await iterator?.next()
+      return try? await iterator.wrappedValue?.next()
     }
   }
 
@@ -79,7 +79,7 @@ extension AsyncStream {
 extension AsyncSequence {
   /// Erases this async sequence to an async stream that produces elements till this sequence
   /// terminates (or fails).
-  public func eraseToStream() -> AsyncStream<Element> {
+  public func eraseToStream() -> AsyncStream<Element> where Self: Sendable {
     AsyncStream(self)
   }
 }

Sources/ConcurrencyExtras/AsyncThrowingStream.swift

@@ -5,16 +5,16 @@ extension AsyncThrowingStream where Failure == Error {
   /// terminates, rethrowing any failure.
   ///
   /// - Parameter sequence: An async sequence.
-  public init<S: AsyncSequence>(_ sequence: S) where S.Element == Element {
+  public init<S: AsyncSequence>(_ sequence: S) where S.Element == Element, S: Sendable {
     let lock = NSLock()
-    var iterator: S.AsyncIterator?
+    let iterator = UncheckedBox<S.AsyncIterator?>(wrappedValue: nil)
     self.init {
       lock.withLock {
-        if iterator == nil {
-          iterator = sequence.makeAsyncIterator()
+        if iterator.wrappedValue == nil {
+          iterator.wrappedValue = sequence.makeAsyncIterator()
         }
       }
-      return try await iterator?.next()
+      return try await iterator.wrappedValue?.next()
     }
   }
 
@@ -34,7 +34,7 @@ extension AsyncThrowingStream where Failure == Error {
 extension AsyncSequence {
   /// Erases this async sequence to an async throwing stream that produces elements till this
   /// sequence terminates, rethrowing any error on failure.
-  public func eraseToThrowingStream() -> AsyncThrowingStream<Element, Error> {
+  public func eraseToThrowingStream() -> AsyncThrowingStream<Element, Error> where Self: Sendable {
     AsyncThrowingStream(self)
   }
 }

Sources/ConcurrencyExtras/Internal/UncheckedBox.swift

@@ -0,0 +1,6 @@
+final class UncheckedBox<Value>: @unchecked Sendable {
+  var wrappedValue: Value
+  init(wrappedValue: Value) {
+    self.wrappedValue = wrappedValue
+  }
+}

Sources/ConcurrencyExtras/LockIsolated.swift

@@ -93,6 +93,7 @@ extension LockIsolated where Value: Sendable {
   }
 }
 
+#if swift(<6)
 @available(*, deprecated, message: "Lock isolated values should not be equatable")
 extension LockIsolated: Equatable where Value: Equatable {
   public static func == (lhs: LockIsolated, rhs: LockIsolated) -> Bool {
@@ -106,6 +107,7 @@ extension LockIsolated: Hashable where Value: Hashable {
     hasher.combine(self.value)
   }
 }
+#endif
 
 extension NSRecursiveLock {
   @inlinable @discardableResult

Sources/ConcurrencyExtras/MainSerialExecutor.swift

@@ -81,9 +81,10 @@
   private typealias Hook = @convention(thin) (UnownedJob, Original) -> Void
 
   private var swift_task_enqueueGlobal_hook: Hook? {
-    get { _swift_task_enqueueGlobal_hook.pointee }
-    set { _swift_task_enqueueGlobal_hook.pointee = newValue }
+    get { _swift_task_enqueueGlobal_hook.wrappedValue.pointee }
+    set { _swift_task_enqueueGlobal_hook.wrappedValue.pointee = newValue }
   }
-  private let _swift_task_enqueueGlobal_hook: UnsafeMutablePointer<Hook?> =
+  private let _swift_task_enqueueGlobal_hook = UncheckedSendable(
     dlsym(dlopen(nil, 0), "swift_task_enqueueGlobal_hook").assumingMemoryBound(to: Hook?.self)
+  )
 #endif