Merge more of the image attachments codebase duplicated between Darwin and Windows.

This PR eliminates a bunch of duplicated code between Darwin and Windows that's
used to support image attachments. We're able to do this because
`_AttachableImageWrapper` is now a class and can be included in conforms-to
generic constraints, so we can write
`where AttachableValue: _AttachableImageWrapper<T> & AttachableWrapper`. It was
previously a structure and structures can't be used in generic constraints this
way.

There's a new public, underscored protocol introduced here, `_AttachableAsImage`,
that serves as a "base" protocol for `AttachableAsCGImage` and
`AttachableAsIWICBitmapSource`. I intend to promote this protocol to API, but it
will need a Swift Evolution proposal first. I'm going to include it in a future
"image attachments refinement" proposal that will cover a few other things.

Author: grynspan

Sources/Overlays/_Testing_CoreGraphics/Attachments/AttachableAsCGImage.swift

@@ -39,7 +39,7 @@ private import ImageIO
 ///   @Available(Swift, introduced: 6.3)
 /// }
 @available(_uttypesAPI, *)
-public protocol AttachableAsCGImage: SendableMetatype {
+public protocol AttachableAsCGImage: _AttachableAsImage, SendableMetatype {
   /// An instance of `CGImage` representing this image.
   ///
   /// - Throws: Any error that prevents the creation of an image.
@@ -68,22 +68,6 @@ public protocol AttachableAsCGImage: SendableMetatype {
   /// This property is not part of the public interface of the testing
   /// library. It may be removed in a future update.
   var _attachmentScaleFactor: CGFloat { get }
-
-  /// Make a copy of this instance to pass to an attachment.
-  ///
-  /// - Returns: A copy of `self`, or `self` if no copy is needed.
-  ///
-  /// The testing library uses this function to take ownership of image
-  /// resources that test authors pass to it. If possible, make a copy of or add
-  /// a reference to `self`. If this type does not support making copies, return
-  /// `self` verbatim.
-  ///
-  /// The default implementation of this function when `Self` conforms to
-  /// `Sendable` simply returns `self`.
-  ///
-  /// This function is not part of the public interface of the testing library.
-  /// It may be removed in a future update.
-  func _copyAttachableValue() -> Self
 }
 
 @available(_uttypesAPI, *)
@@ -95,6 +79,8 @@ extension AttachableAsCGImage {
   public var _attachmentScaleFactor: CGFloat {
     1.0
   }
+
+  public func _deinitializeAttachableValue() {}
 }
 
 @available(_uttypesAPI, *)

Sources/Overlays/_Testing_CoreGraphics/CMakeLists.txt

@@ -11,7 +11,6 @@ if(APPLE)
     Attachments/_AttachableImageWrapper+AttachableWrapper.swift
     Attachments/AttachableAsCGImage.swift
     Attachments/AttachableImageFormat+UTType.swift
-    Attachments/Attachment+AttachableAsCGImage.swift
     Attachments/CGImage+AttachableAsCGImage.swift
     ReexportTesting.swift)
 

Sources/Overlays/_Testing_WinSDK/Attachments/AttachableAsIWICBitmapSource.swift

@@ -113,7 +113,7 @@ public protocol _AttachableByAddressAsIWICBitmapSource {
 /// you have an image in another format that needs to be attached to a test,
 /// first convert it to an instance of one of the types above.
 @_spi(Experimental)
-public protocol AttachableAsIWICBitmapSource: SendableMetatype {
+public protocol AttachableAsIWICBitmapSource: _AttachableAsImage, SendableMetatype {
   /// Create a WIC bitmap source representing an instance of this type.
   ///
   /// - Returns: A pointer to a new WIC bitmap source representing this image.
@@ -145,39 +145,6 @@ public protocol AttachableAsIWICBitmapSource: SendableMetatype {
   func _copyAttachableIWICBitmapSource(
     using factory: UnsafeMutablePointer<IWICImagingFactory>
   ) throws -> UnsafeMutablePointer<IWICBitmapSource>
-
-  /// Make a copy of this instance.
-  ///
-  /// - Returns: A copy of `self`, or `self` if this type does not support a
-  ///   copying operation.
-  ///
-  /// The testing library uses this function to take ownership of image
-  /// resources that test authors pass to it. If possible, make a copy of or add
-  /// a reference to `self`. If this type does not support making copies, return
-  /// `self` verbatim.
-  ///
-  /// The default implementation of this function when `Self` conforms to
-  /// `Sendable` simply returns `self`.
-  ///
-  /// This function is not part of the public interface of the testing library.
-  /// It may be removed in a future update.
-  func _copyAttachableValue() -> Self
-
-  /// Manually deinitialize any resources associated with this image.
-  ///
-  /// The implementation of this function cleans up any resources (such as
-  /// handles or COM objects) associated with this image. The testing library
-  /// automatically invokes this function as needed.
-  ///
-  /// This function is not responsible for releasing the image returned from
-  /// `_copyAttachableIWICBitmapSource(using:)`.
-  ///
-  /// The default implementation of this function when `Self` conforms to
-  /// `Sendable` does nothing.
-  ///
-  /// This function is not part of the public interface of the testing library.
-  /// It may be removed in a future update.
-  func _deinitializeAttachableValue()
 }
 
 extension AttachableAsIWICBitmapSource {

Sources/Overlays/_Testing_WinSDK/Attachments/Attachment+AttachableAsIWICBitmapSource.swift

@@ -30,7 +30,7 @@ extension UnsafeMutablePointer: AttachableAsIWICBitmapSource where Pointee: _Att
     Pointee._copyAttachableValue(at: self)
   }
 
-  public consuming func _deinitializeAttachableValue() {
+  public func _deinitializeAttachableValue() {
     Pointee._deinitializeAttachableValue(at: self)
   }
 }

Sources/Overlays/_Testing_WinSDK/Attachments/UnsafeMutablePointer+AttachableAsIWICBitmapSource.swift

@@ -11,7 +11,6 @@ if (CMAKE_SYSTEM_NAME STREQUAL "Windows")
     Attachments/_AttachableImageWrapper+AttachableWrapper.swift
     Attachments/AttachableAsIWICBitmapSource.swift
     Attachments/AttachableImageFormat+CLSID.swift
-    Attachments/Attachment+AttachableAsIWICBitmapSource.swift
     Attachments/HBITMAP+AttachableAsIWICBitmapSource.swift
     Attachments/HICON+AttachableAsIWICBitmapSource.swift
     Attachments/IWICBitmapSource+AttachableAsIWICBitmapSource.swift

Sources/Overlays/_Testing_WinSDK/CMakeLists.txt

@@ -8,9 +8,6 @@
 // See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 //
 
-#if SWT_TARGET_OS_APPLE && canImport(CoreGraphics)
-public import Testing
-
 @available(_uttypesAPI, *)
 extension Attachment {
   /// Initialize an instance of this type that encloses the given image.
@@ -52,12 +49,8 @@ extension Attachment {
     named preferredName: String? = nil,
     as imageFormat: AttachableImageFormat? = nil,
     sourceLocation: SourceLocation = #_sourceLocation
-  ) where T: AttachableAsCGImage, AttachableValue == _AttachableImageWrapper<T> {
-    let imageWrapper = _AttachableImageWrapper(
-      image: image._copyAttachableValue(),
-      imageFormat: imageFormat,
-      deinitializingWith: { _ in }
-    )
+  ) where AttachableValue: _AttachableImageWrapper<T> & AttachableWrapper {
+    let imageWrapper = AttachableValue(image: image, imageFormat: imageFormat)
     self.init(imageWrapper, named: preferredName, sourceLocation: sourceLocation)
   }
 
@@ -99,7 +92,7 @@ extension Attachment {
     named preferredName: String? = nil,
     as imageFormat: AttachableImageFormat? = nil,
     sourceLocation: SourceLocation = #_sourceLocation
-  ) where T: AttachableAsCGImage, AttachableValue == _AttachableImageWrapper<T> {
+  ) where AttachableValue: _AttachableImageWrapper<T> & AttachableWrapper {
     let attachment = Self(image, named: preferredName, as: imageFormat, sourceLocation: sourceLocation)
     Self.record(attachment, sourceLocation: sourceLocation)
   }
@@ -109,11 +102,10 @@ extension Attachment {
 
 @_spi(Experimental) // STOP: not part of ST-0014
 @available(_uttypesAPI, *)
-extension Attachment where AttachableValue: AttachableWrapper, AttachableValue.Wrapped: AttachableAsCGImage {
+extension Attachment where AttachableValue: AttachableWrapper, AttachableValue.Wrapped: _AttachableAsImage {
   /// The image format to use when encoding the represented image.
   @_disfavoredOverload public var imageFormat: AttachableImageFormat? {
     // FIXME: no way to express `where AttachableValue == _AttachableImageWrapper<???>` on a property (see rdar://47559973)
     (attachableValue as? _AttachableImageWrapper<AttachableValue.Wrapped>)?.imageFormat
   }
 }
-#endif

Sources/Overlays/_Testing_CoreGraphics/Attachments/Attachment+AttachableAsCGImage.swift renamed to Sources/Testing/Attachments/Images/Attachment+_AttachableAsImage.swift

@@ -0,0 +1,54 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024–2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+/// A protocol describing images that can be converted to instances of
+/// [`Attachment`](https://developer.apple.com/documentation/testing/attachment).
+///
+/// This protocol acts as an abstract, platform-independent base protocol for
+/// ``AttachableAsCGImage`` and ``AttachableAsIWICBitmapSource``.
+///
+/// @Comment {
+///   A future Swift Evolution proposal will promote this protocol to API so
+///   that we don't need to underscore its name.
+/// }
+@available(_uttypesAPI, *)
+public protocol _AttachableAsImage: SendableMetatype {
+  /// Make a copy of this instance to pass to an attachment.
+  ///
+  /// - Returns: A copy of `self`, or `self` if no copy is needed.
+  ///
+  /// The testing library uses this function to take ownership of image
+  /// resources that test authors pass to it. If possible, make a copy of or add
+  /// a reference to `self`. If this type does not support making copies, return
+  /// `self` verbatim.
+  ///
+  /// The default implementation of this function when `Self` conforms to
+  /// `Sendable` simply returns `self`.
+  ///
+  /// This function is not part of the public interface of the testing library.
+  /// It may be removed in a future update.
+  func _copyAttachableValue() -> Self
+
+  /// Manually deinitialize any resources associated with this image.
+  ///
+  /// The implementation of this function cleans up any resources (such as
+  /// handles or COM objects) associated with this image. The testing library
+  /// automatically invokes this function as needed.
+  ///
+  /// This function is not responsible for releasing the image returned from
+  /// `_copyAttachableIWICBitmapSource(using:)`.
+  ///
+  /// The default implementation of this function when `Self` conforms to
+  /// `Sendable` does nothing.
+  ///
+  /// This function is not part of the public interface of the testing library.
+  /// It may be removed in a future update.
+  func _deinitializeAttachableValue()
+}

Sources/Testing/Attachments/Images/_AttachableAsImage.swift

@@ -21,24 +21,20 @@
 /// | Windows | [`HBITMAP`](https://learn.microsoft.com/en-us/windows/win32/gdi/bitmaps), [`HICON`](https://learn.microsoft.com/en-us/windows/win32/menurc/icons), [`IWICBitmapSource`](https://learn.microsoft.com/en-us/windows/win32/api/wincodec/nn-wincodec-iwicbitmapsource) (including its subclasses declared by Windows Imaging Component) |
 /// }
 @available(_uttypesAPI, *)
-public final class _AttachableImageWrapper<Image>: Sendable {
+public final class _AttachableImageWrapper<Image>: Sendable where Image: _AttachableAsImage {
   /// The underlying image.
   private nonisolated(unsafe) let _image: Image
 
   /// The image format to use when encoding the represented image.
   package let imageFormat: AttachableImageFormat?
 
-  /// A deinitializer function to call to clean up `image`.
-  private let _deinit: @Sendable (consuming Image) -> Void
-
-  package init(image: Image, imageFormat: AttachableImageFormat?, deinitializingWith `deinit`: @escaping @Sendable (consuming Image) -> Void) {
-    self._image = image
+  init(image: Image, imageFormat: AttachableImageFormat?) {
+    self._image = image._copyAttachableValue()
     self.imageFormat = imageFormat
-    self._deinit = `deinit`
   }
 
   deinit {
-    _deinit(_image)
+    _image._deinitializeAttachableValue()
   }
 }
 

Sources/Testing/Attachments/Images/_AttachableImageWrapper.swift

@@ -21,8 +21,10 @@ add_library(Testing
   ABI/Encoded/ABI.EncodedIssue.swift
   ABI/Encoded/ABI.EncodedMessage.swift
   ABI/Encoded/ABI.EncodedTest.swift
+  Attachments/Images/_AttachableAsImage.swift
   Attachments/Images/_AttachableImageWrapper.swift
   Attachments/Images/AttachableImageFormat.swift
+  Attachments/Images/Attachment+_AttachableAsImage.swift
   Attachments/Images/ImageAttachmentError.swift
   Attachments/Attachable.swift
   Attachments/AttachableWrapper.swift