Mark APIs that reference SequenceOutput.Buffer with @available(SubprocessSpan, *) so they compile with Swift 6.2

Author: Ryan Dingman

Sources/Subprocess/AsyncBufferSequence.swift

@@ -75,6 +75,9 @@ public struct AsyncBufferSequence: AsyncSequence, Sendable {
 }
 
 extension TrackedPlatformDiskIO {
+#if SubprocessSpan
+@available(SubprocessSpan, *)
+#endif
     internal enum StreamStatus {
         case data(SequenceOutput.Buffer)
         case endOfStream(SequenceOutput.Buffer)

Sources/Subprocess/Platforms/Subprocess+Unix.swift

@@ -461,6 +461,9 @@ extension CreatedPipe {
 
 // MARK: - TrackedDispatchIO extensions
 extension TrackedDispatchIO {
+#if SubprocessSpan
+@available(SubprocessSpan, *)
+#endif
     internal func readDataStream(upToLength maxLength: Int) -> AsyncThrowingStream<StreamStatus, Swift.Error> {
         return AsyncThrowingStream<StreamStatus, Swift.Error> { continuation in
             self.dispatchIO.read(

Sources/Subprocess/Platforms/Subprocess+Windows.swift

@@ -1043,6 +1043,9 @@ extension CreatedPipe {
 }
 
 extension TrackedFileDescriptor {
+#if SubprocessSpan
+@available(SubprocessSpan, *)
+#endif
     internal func readDataStream(upToLength maxLength: Int) -> AsyncThrowingStream<StreamStatus, Swift.Error> {
         return AsyncThrowingStream<StreamStatus, Swift.Error> { continuation in
             do {