Unwrap RCWs that are passed to Marshal.GetIUnknownForObject when using the global marshalling ComWrappers instance

[jkoritzinsky]

Fixes issue reported in #115317

Depends on #113907

[Copilot]

Pull Request Overview

This pull request implements changes to support unwrapping RCWs when passed to Marshal.GetIUnknownForObject under the global marshalling ComWrappers instance. Key changes include refactoring of TrackerObjectManager methods, updates to COM‐aware weak reference handling in both native and CoreCLR code, and enhancements to GC collection APIs to support new parameters such as lowMemoryPressure.

Reviewed Changes

Copilot reviewed 60 out of 60 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
TrackerObjectManager.NativeAot.cs	Updated to use partial methods and new patterns for registering and tracking external COM objects.
ComAwareWeakReference.CoreCLR.cs	Adjusted signature and logic to differentiate between built-in COM and ComWrappers RCWs.
GC.NativeAot.cs	Extended GC.Collect overloads to include a lowMemoryPressure parameter.
interop/inc/interoplibimports.h	Modified the IteratorNext API signature from HRESULT to bool.
System.Private.CoreLib.csproj	Updated project file to include new CoreCLR sources for ComAwareWeakReference and TrackerObjectManager.
(Several other interop and debug files)	Various changes to align unmanaged COM interop logic with the new unwrapping behavior.

Comments suppressed due to low confidence (3)

src/coreclr/interop/inc/interoplibimports.h:25

• Ensure that changing the return type of IteratorNext from HRESULT to bool is thoroughly validated for backward compatibility across all interop consumers.

bool IteratorNext(_In_ RuntimeCallContext* runtimeContext, _Outptr_result_maybenull_ void** trackerTarget, _Outptr_result_maybenull_ InteropLib::OBJECTHANDLE* proxyObject) noexcept;

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/TrackerObjectManager.NativeAot.cs:94

• Ensure that the new AddReferencePath method is consistently used across the interop code for proper reference tracking and verify its thread-safety in concurrent scenarios.

public static bool AddReferencePath(object target, object foundReference)

src/coreclr/nativeaot/System.Private.CoreLib/src/System/GC.NativeAot.cs:145

• Ensure that the new lowMemoryPressure parameter is correctly propagated to RuntimeImports.RhCollect and that any downstream logic handles this flag as expected to avoid unexpected GC behavior.

Collect(generation, mode, blocking, compacting, lowMemoryPressure: false);

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[Copilot]

Pull Request Overview

This PR updates the marshalling behavior for RCWs by unwrapping COM objects passed to Marshal.GetIUnknownForObject when using the global marshalling ComWrappers instance. Key changes include updating test assertions to use Assert.Same for reference equality, modifying the global marshalling logic in ComWrappers.cs to favor an existing COM instance if available, and adjusting the behavior in ComWrappers.CoreCLR.cs for obtaining COM interfaces and objects.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/tests/Interop/COM/ComWrappers/GlobalInstance/GlobalInstance.cs	Updates test assertions to check for reference equality and adds a new IID_IUNKNOWN constant.
src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/ComWrappers.cs	Adds a conditional for trying to obtain an existing COM instance before creating one, and propagates CreateObjectFlags via the API.
src/coreclr/System.Private/CoreLib/src/System/Runtime/InteropServices/ComWrappers.CoreCLR.cs	Adjusts global instance handling to short-circuit when the global instance is null and delegates to the updated methods in ComWrappers.cs.

Comments suppressed due to low confidence (1)

src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/ComWrappers.CoreCLR.cs:80

• When s_globalInstanceForMarshalling is null, consider returning null instead of IntPtr.Zero to better match the expected object return type and maintain consistency with similar methods.

if (s_globalInstanceForMarshalling == null)