[ObjCRuntime] Improve super calls - Fixes #25362

[rolfbjarne]

Summary

Introduces a stack-allocated ObjCSuper struct to replace the use of NSObject.SuperHandle for objc_msgSendSuper calls. This eliminates the need to allocate and manage unmanaged memory for the objc_super struct on every super call.

Changes

• New ObjCSuper readonly ref struct (src/ObjCRuntime/ObjCSuper.cs): A [StructLayout(LayoutKind.Sequential)] struct with Receiver and ClassHandle fields matching the native objc_super layout.

• Updated bgen code generation: P/Invoke declarations for objc_msgSendSuper variants now take ObjCSuper* instead of IntPtr as the first parameter. Generated call sites create a stack-allocated ObjCSuper and pass &__objc_super__ instead of this.SuperHandle.

• Updated handwritten super calls in 11 source files (CIFilter, CIVector, CALayer, UIPasteboard, NSInputStream, NSUuid, NSThread, NSHttpCookie, GCMouse, NSOpenGLPixelFormat, NSBitmapImageRep) plus NSObject2.cs.

• NSObject.SuperHandle is preserved for backward compatibility (can be simplified/removed in XAMCORE_5_0).

Fixes #25362

🤖 Pull request created by Copilot

[rolfbjarne]

/review

[github-actions]

✅ .NET for Apple Platforms PR Reviewer completed successfully!

[github-actions]

Review Summary

This PR successfully modernizes super call handling by replacing heap-allocated objc_super structures (via NSObject.SuperHandle) with stack-allocated ObjCSuper structs. The changes are well-executed and consistent across both generated and handwritten code.

✅ Strengths

1. Correct memory management: All super call sites properly create ObjCSuper on the stack and include GC.KeepAlive (this) to prevent premature collection
2. Consistent pattern: The bgen generator correctly emits the new pattern with unsafe blocks, stack allocation, and GC safety
3. Binary layout correctness: The ObjCSuper struct uses [StructLayout(LayoutKind.Sequential)] with the correct field order (receiver, classHandle) matching the native objc_super layout
4. Backward compatibility: NSObject.SuperHandle is preserved (mentioned in PR description as simplifiable in XAMCORE_5_0)
5. Proper P/Invoke signatures: All objc_msgSendSuper variants correctly updated to take ObjCSuper* instead of IntPtr

🎯 Findings

• 3 suggestions for minor improvements to API design, code organization, and documentation

Key Changes Validated

• ✅ ObjCSuper struct correctly implements objc_super layout
• ✅ All handwritten super calls (11 files) updated consistently
• ✅ Generator correctly emits unsafe blocks with stack allocation
• ✅ GC.KeepAlive (this) present after all super calls
• ✅ Return values properly captured before GC.KeepAlive where needed
• ✅ Test expectations updated for size changes
• ✅ CI checks passing (many completed, remainder in progress)

The implementation is sound and ready for merge after considering the minor suggestions above.

Generated by .NET for Apple Platforms PR Reviewer for issue #25376 · ● 7.1M

[vs-mobiletools-engineering-service2]

✅ [PR Build #7966a34] Build passed (Detect API changes) ✅

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✅ [PR Build #7966a34] Build passed (Build packages) ✅

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Hash: 7966a3435d7b0527fddd04a77b2d64b8db6ac9b4 [PR build]

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✅ API diff for current PR / commit

NET (empty diffs)

• iOS: vsdrops gist ( No breaking changes )
• tvOS: vsdrops gist ( No breaking changes )
• MacCatalyst: vsdrops gist ( No breaking changes )
• macOS: vsdrops gist ( No breaking changes )

✅ API diff vs stable

NET (empty diffs)

• iOS: vsdrops gist ( No breaking changes )
• tvOS: vsdrops gist ( No breaking changes )
• MacCatalyst: vsdrops gist ( No breaking changes )
• macOS: vsdrops gist ( No breaking changes )

ℹ️ Generator diff

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Hash: 7966a3435d7b0527fddd04a77b2d64b8db6ac9b4 [PR build]

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✅ [PR Build #7966a34] Build passed (Build macOS tests) ✅

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Hash: 7966a3435d7b0527fddd04a77b2d64b8db6ac9b4 [PR build]

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🚀 [CI Build #7966a34] Test results 🚀

Test results

✅ All tests passed on VSTS: test results.

🎉 All 175 tests passed 🎉

Tests counts

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (MacCatalyst): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (tvOS): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 4 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ generator: All 5 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 6 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ linker: All 44 tests passed. Html Report (VSDrops) Download
✅ monotouch (iOS): All 16 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 18 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 18 tests passed. Html Report (VSDrops) Download
✅ monotouch (tvOS): All 16 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ sharpie: All 1 tests passed. (⚠️ Html Report Publish failed ⚠️) Download
✅ windows: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. (⚠️ Html Report Publish failed ⚠️) Download

macOS tests

✅ Tests on macOS Monterey (12): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Ventura (13): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sonoma (14): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Sequoia (15): All 5 tests passed. Html Report (VSDrops) Download
✅ Tests on macOS Tahoe (26): All 5 tests passed. Html Report (VSDrops) Download

Linux Build Verification

✅ Linux build succeeded

Pipeline on Agent
Hash: 7966a3435d7b0527fddd04a77b2d64b8db6ac9b4 [PR build]