Availability macro support for back-deployed Span

Author: glessard

Package.swift

@@ -12,63 +12,57 @@
 
 import PackageDescription
 
-struct Available {
+struct Availability {
   var name: String
   var version: String
   var osAvailability: String
-  var sourceAvailability: String
 
-  init(
-    _ version: String,
-    _ osAvailability: String
-  ) {
-    self.name = "System"
-    self.version = version
-    self.osAvailability = osAvailability
-    self.sourceAvailability = "macOS 10.10, iOS 8.0, watchOS 2.0, tvOS 9.0, visionOS 1.0"
+  var minOSVersions: String {
+    "macOS 10.10, iOS 8.0, watchOS 2.0, tvOS 9.0, visionOS 1.0"
   }
-
-  var swiftSetting: SwiftSetting {
-    #if SYSTEM_ABI_STABLE
-    // Use availability matching Darwin API.
-    let availability = self.osAvailability
-    #else
-    // Use availability matching SwiftPM default.
-    let availability = self.sourceAvailability
-    #endif
-    return .enableExperimentalFeature(
-      "AvailabilityMacro=\(self.name) \(version):\(availability)")
+  var spanOSVersions: String {
+    "macOS 10.14.4, iOS 12.2, watchOS 5.2, tvOS 12.2, visionOS 1.0"
   }
-}
-
-let availability: [Available] = [
-  Available("0.0.1", "macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0"),
-
-  Available("0.0.2", "macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0"),
 
-  Available("0.0.3", "macOS 12.3, iOS 15.4, watchOS 8.5, tvOS 15.4"),
-  Available("1.1.0", "macOS 12.3, iOS 15.4, watchOS 8.5, tvOS 15.4"),
-
-  Available("1.1.1", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4"),
-  Available("1.2.0", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4"),
-
-  Available("1.2.1", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4"),
-  Available("1.3.0", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4"),
-
-  Available("1.3.1", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4, visionOS 1.0"),
-  Available("1.3.2", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4, visionOS 1.0"),
-  Available("1.4.0", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4, visionOS 1.0"),
+  var isStandardAvailability: Bool { name == "System" }
+}
 
-  Available("1.4.1", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
-  Available("1.4.2", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
-  Available("1.5.0", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
-  Available("1.6.0", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
-  Available("1.6.1", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
+let availabilityMap: [(String, String)] = [
+  ("0.0.1", "macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0"),
+  ("0.0.2", "macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0"),
+  ("1.1.0", "macOS 12.3, iOS 15.4, watchOS 8.5, tvOS 15.4"),
+  ("1.2.0", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4"),
+  ("1.4.0", "macOS 14.4, iOS 17.4, watchOS 10.4, tvOS 17.4, visionOS 1.0"),
 
-  Available("99", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
+  ("99", "macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, visionOS 9999"),
 ]
 
-let swiftSettingsAvailability = availability.map(\.swiftSetting)
+let availabilities: [Availability] =
+  availabilityMap.map {
+    Availability(name: "System", version: $0.0, osAvailability: $0.1)
+  } + availabilityMap.prefix(5).map {
+    Availability(name: "SystemWithSpan", version: $0.0, osAvailability: $0.1)
+  }
+
+let swiftSettingsAvailability = availabilities.map {
+  availability -> SwiftSetting in
+  let osVersionList: String
+#if SYSTEM_ABI_STABLE
+  // Use availability matching Darwin API.
+  availability = availability.osAvailability
+#else
+  if availability.isStandardAvailability {
+    // Use availability matching SwiftPM minimum.
+    osVersionList = availability.minOSVersions
+  } else {
+    // Use availability matching Span deployment minimum.
+    osVersionList = availability.spanOSVersions
+  }
+#endif
+  return .enableExperimentalFeature(
+    "AvailabilityMacro=\(availability.name) \(availability.version):\(osVersionList)"
+  )
+}
 
 #if SYSTEM_CI
 let swiftSettingsCI: [SwiftSetting] = [

Sources/System/FileHelpers.swift

@@ -20,6 +20,7 @@ extension FileDescriptor {
   /// If `body` throws an error
   /// or an error occurs while closing the file descriptor,
   /// this method rethrows that error.
+  @available(System 0.0.1, *)
   public func closeAfter<R>(_ body: () throws -> R) throws -> R {
     // No underscore helper, since the closure's throw isn't necessarily typed.
     let result: R
@@ -49,6 +50,7 @@ extension FileDescriptor {
   /// If `sequence` doesn't implement
   /// the <doc://com.apple.documentation/documentation/swift/sequence/3128824-withcontiguousstorageifavailable> method,
   /// temporary space will be allocated as needed.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   @discardableResult
   public func writeAll<S: Sequence>(
@@ -98,6 +100,7 @@ extension FileDescriptor {
   /// If `sequence` doesn't implement
   /// the <doc://com.apple.documentation/documentation/swift/sequence/3128824-withcontiguousstorageifavailable> method,
   /// temporary space will be allocated as needed.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   @discardableResult
   public func writeAll<S: Sequence>(
@@ -106,6 +109,7 @@ extension FileDescriptor {
     try _writeAll(toAbsoluteOffset: offset, sequence).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _writeAll<S: Sequence>(
     toAbsoluteOffset offset: Int64, _ sequence: S
@@ -115,6 +119,7 @@ extension FileDescriptor {
     }
   }
 
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   internal func _writeAllBuffer(
     toAbsoluteOffset offset: Int64, _ buffer: UnsafeRawBufferPointer
@@ -134,6 +139,7 @@ extension FileDescriptor {
     return .success(buffer.count)
   }
 
+#if compiler(>=6.2)
   /// Writes the entire contents of a buffer, retrying on partial writes.
   ///
   /// - Parameters:
@@ -150,7 +156,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `write`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func writeAll(
     _ data: RawSpan,
@@ -177,7 +183,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pwrite`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func writeAll(
     toAbsoluteOffset offset: Int64,
@@ -205,7 +211,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `read`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   @discardableResult
   public func read(
@@ -238,7 +244,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pread`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   @discardableResult
   public func read(
@@ -257,4 +263,5 @@ extension FileDescriptor {
     }
     return originalCapacity - buffer.freeCapacity
   }
+#endif // swift(>=6.2)
 }

Sources/System/FileOperations.swift

@@ -23,6 +23,7 @@ extension FileDescriptor {
   /// - Returns: A file descriptor for the open file
   ///
   /// The corresponding C function is `open`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public static func open(
     _ path: FilePath,
@@ -62,6 +63,7 @@ extension FileDescriptor {
   /// - Returns: A file descriptor for the open file
   ///
   /// The corresponding C function is `open`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public static func open(
     _ path: UnsafePointer<CChar>,
@@ -75,6 +77,7 @@ extension FileDescriptor {
     ).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal static func _open(
     _ path: UnsafePointer<CChar>,
@@ -148,6 +151,7 @@ extension FileDescriptor {
   /// the object will be deactivated.
   ///
   /// The corresponding C function is `close`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public func close() throws { try _close().get() }
 
@@ -165,6 +169,7 @@ extension FileDescriptor {
   ///   in bytes from the beginning of the file.
   ///
   /// The corresponding C function is `lseek`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   @discardableResult
   public func seek(
@@ -173,6 +178,7 @@ extension FileDescriptor {
     try _seek(offset: offset, from: whence).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _seek(
     offset: Int64, from whence: FileDescriptor.SeekOrigin
@@ -210,6 +216,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `read`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public func read(
     into buffer: UnsafeMutableRawBufferPointer,
@@ -218,6 +225,7 @@ extension FileDescriptor {
     try _read(into: buffer, retryOnInterrupt: retryOnInterrupt).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _read(
     into buffer: UnsafeMutableRawBufferPointer,
@@ -246,6 +254,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pread`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public func read(
     fromAbsoluteOffset offset: Int64,
@@ -259,6 +268,7 @@ extension FileDescriptor {
     ).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _read(
     fromAbsoluteOffset offset: Int64,
@@ -299,6 +309,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `write`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public func write(
     _ buffer: UnsafeRawBufferPointer,
@@ -307,6 +318,7 @@ extension FileDescriptor {
     try _write(buffer, retryOnInterrupt: retryOnInterrupt).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _write(
     _ buffer: UnsafeRawBufferPointer,
@@ -332,6 +344,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pwrite`.
+  @available(System 0.0.1, *)
   @_alwaysEmitIntoClient
   public func write(
     toAbsoluteOffset offset: Int64,
@@ -341,6 +354,7 @@ extension FileDescriptor {
     try _write(toAbsoluteOffset: offset, buffer, retryOnInterrupt: retryOnInterrupt).get()
   }
 
+  @available(System 0.0.1, *)
   @usableFromInline
   internal func _write(
     toAbsoluteOffset offset: Int64,
@@ -366,6 +380,7 @@ extension FileDescriptor {
       retryOnInterrupt: retryOnInterrupt)
   }
 
+#if compiler(>=6.2)
   /// Writes the contents of a buffer at the current file offset.
   ///
   /// - Parameters:
@@ -382,7 +397,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `write`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func write(
     _ data: RawSpan,
@@ -408,7 +423,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pwrite`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func write(
     toAbsoluteOffset offset: Int64,
@@ -420,7 +435,7 @@ extension FileDescriptor {
     }
   }
 
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   internal func _readIntoOutputBuffer(
     _ buffer: UnsafeMutableRawBufferPointer,
@@ -459,7 +474,7 @@ extension FileDescriptor {
   /// call the ``seek(offset:from:)`` method.
   ///
   /// The corresponding C function is `read`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func read(
     into buffer: inout OutputRawSpan,
@@ -485,7 +500,7 @@ extension FileDescriptor {
   /// this method leaves the file's existing offset unchanged.
   ///
   /// The corresponding C function is `pread`.
-  @available(macOS 15, iOS 18, watchOS 11, tvOS 18, visionOS 2, *)
+  @available(SystemWithSpan 0.0.1, *)
   @_alwaysEmitIntoClient
   public func read(
     fromAbsoluteOffset offset: Int64,
@@ -509,6 +524,7 @@ extension FileDescriptor {
       fatalError("Unexpected error type")
     }
   }
+#endif // compiler(>=6.2)
 }
 
 #if !os(WASI)