Convert more COM interop MethodDescCallSite to UnmanagedCallersOnly (UCO) by Copilot · Pull Request #125849 · dotnet/runtime

Copilot · 2026-03-20T18:08:33Z

Continues the COM interop UCO migration (group 5), converting three MethodDescCallSite call sites to the UCO pattern and removing associated dead code. Addresses all pending feedback from #125508.

Description

New UCO helpers in `StubHelpers.cs`

GetDispatchExPropertyFlags – replaces two MethodDescCallSite calls for PropertyInfo.CanRead/CanWrite in DispatchEx_GetMemberProperties; returns int directly via InvokeThrowing_Ret at the callsite (no out-param)
CallICustomQueryInterface – replaces the InvokeICustomQueryInterfaceGetInterface_CallBack struct/callback pattern; returns int directly (uses InvokeThrowing_Ret)
InvokeConnectionPointProviderMethod – replaces two MethodDescCallSite calls in ConnectionPoint::InvokeProviderMethod; uses nint/UIntPtr ctor fallback for correctness; uses GetMultiCallableAddrOfCode() for the event target since it is stored for future invokes
Added [RequiresUnsafe] to the existing GetIEnumeratorToEnumVariantMarshaler UCO overload for consistency

Feedback addressed

INVOKE_CONNECTION_POINT_PROVIDER_METHOD registered as NoSig in corelib.h (has unmanaged fn-ptr params — encoding in metasig not worth the pain)
CallICustomQueryInterface uses InvokeThrowing_Ret<INT32> and passes ppUnkOut directly — no local copy needed
GetDispatchExPropertyFlags signature changed to return int directly; metasig (SM_PtrPropertyInfo_PtrException_RetInt) and corelib.h registration updated accordingly; callsite in stdinterfaces.cpp updated to use InvokeThrowing_Ret<INT32>
UIntPtr ctor fallback restored in ConnectionPoint::InvokeProviderMethod for correctness
Comment updated in comconnectionpoints.cpp to clarify why GetMultiCallableAddrOfCode() is used for the event target

Dead code removed

InvokeICustomQueryInterfaceGetInterface_CallBack + arg struct in comcallablewrapper.cpp
GetICustomQueryInterfaceGetInterfaceMD / m_pICustomQueryInterfaceGetInterfaceMD from ComCallWrapperTemplate
m_ohDelegate union field and GetOHDelegate/SetOHDelegate/GetObjCreateDelegate/SetObjCreateDelegate from EEClass/MethodTable — SetObjCreateDelegate had no callers; the delegate-based CreateAggregatedInstance path was effectively dead

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Converts COM interop code from MethodDescCallSite to UnmanagedCallersOnly (UCO) pattern for three sites: 1. DispatchEx_GetMemberProperties (Property case): replaces two MethodDescCallSite invocations (for CanRead/CanWrite) with a single UCO helper GetDispatchExPropertyFlags in StubHelpers. 2. ICustomQueryInterface.GetInterface: replaces the callback struct pattern with a UCO helper CallICustomQueryInterface. Also removes the cached MethodDesc field m_pICustomQueryInterfaceGetInterfaceMD from ComCallWrapperTemplate. 3. ConnectionPoint.InvokeProviderMethod: replaces MethodDescCallSite calls for delegate construction and provider invocation with a single UCO helper InvokeConnectionPointProviderMethod. Removes the UIntPtr ctor fallback path (addressing pending feedback). Also removes the m_ohDelegate field and related methods (GetOHDelegate/SetOHDelegate/GetObjCreateDelegate/SetObjCreateDelegate) from EEClass/MethodTable since the delegate-based COM object creation callback feature in CreateAggregatedInstance is removed. Adds [RequiresUnsafe] to GetIEnumeratorToEnumVariantMarshaler UCO overload to be consistent with the new UCO methods. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/coreclr/vm/comcallablewrapper.cpp

src/coreclr/vm/comconnectionpoints.cpp

dotnet-policy-service · 2026-03-20T18:25:53Z

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Copilot

Pull request overview

This PR continues the CoreCLR COM interop migration away from MethodDescCallSite toward the UnmanagedCallersOnly (UCO) reverse-P/Invoke calling pattern, and removes now-dead COM interop callback/delegate infrastructure in the VM.

Changes:

Added new UCO helpers in StubHelpers.cs and updated native call sites to use UnmanagedCallersOnlyCaller.
Converted COM interop call paths in stdinterfaces.cpp, comconnectionpoints.cpp, and comcallablewrapper.cpp from MethodDescCallSite to UCO-based helpers.
Removed dead COM interop delegate/callback code paths and related cached fields/helpers in VM types.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/coreclr/vm/stdinterfaces.cpp	Uses UCO helper to query `PropertyInfo.CanRead/CanWrite` flags instead of two `MethodDescCallSite` calls.
src/coreclr/vm/runtimecallablewrapper.cpp	Removes unused delegate-based aggregated COM instance creation path and related logic.
src/coreclr/vm/methodtable.h	Removes delegate-handle-related APIs from `MethodTable`.
src/coreclr/vm/methodtable.cpp	Removes implementations for COM object-creation delegate storage/retrieval.
src/coreclr/vm/metasig.h	Adds COM-interp UCO metasig definitions for new StubHelpers methods.
src/coreclr/vm/corelib.h	Registers new `StubHelpers` methods (including a `NoSig` entry).
src/coreclr/vm/comconnectionpoints.cpp	Uses a single UCO helper to construct delegate + invoke provider method.
src/coreclr/vm/comcallablewrapper.h	Removes cached `ICustomQueryInterface.GetInterface` MethodDesc field/API.
src/coreclr/vm/comcallablewrapper.cpp	Replaces callback/cached-MD pattern with UCO helper that calls `ICustomQueryInterface.GetInterface`.
src/coreclr/vm/class.h	Removes now-dead delegate handle storage from `EEClass` COM interop union.
src/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs	Adds UCO helpers for DispatchEx property flags, `ICustomQueryInterface`, and connection point invocation.

src/coreclr/vm/stdinterfaces.cpp

AaronRobinsonMSFT

Some minor nits. Otherwise, looks good when green.

src/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs

src/coreclr/vm/stdinterfaces.cpp

src/coreclr/vm/comconnectionpoints.cpp

…InvokeThrowing_Ret Co-authored-by: AaronRobinsonMSFT <30635565+AaronRobinsonMSFT@users.noreply.github.com> Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/dde670ee-197d-4271-8596-d75d3cca3116

jkotas · 2026-03-24T04:11:11Z

/ba-g timeouts

am11 · 2026-03-24T09:16:47Z

@jkotas, it would be good to ask copilot to keep the author of original commit and add stuff on top.

am11@ae7563a has dispatchinfo conversions. I tested it last week but haven't retested after the cherry-pick (should be fine). Copilot can pick it and continue the next batch.

jkotas · 2026-03-25T04:46:58Z

am11@ae7563a

Triggered copilot on it with explicit instruction to preserve the author name and some initial feedback, let's see how it does.

Copilot AI assigned Copilot and jkotas Mar 20, 2026

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jkotas mentioned this pull request Mar 20, 2026

Convert more COM interop MethodDescCallSite to UCO #125508

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jkotas marked this pull request as ready for review March 20, 2026 20:41

jkotas requested review from AaronRobinsonMSFT and Copilot March 20, 2026 20:41

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Merge branch 'main' into copilot/address-pending-feedback

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build-analysis bot mentioned this pull request Mar 23, 2026

[Android][CoreCLR] System.Security.Cryptography.Tests killed by lowmemorykiller #118603

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Merge branch 'main' into copilot/address-pending-feedback

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Copilot started work on behalf of AaronRobinsonMSFT March 23, 2026 22:45 View session

Address review feedback: GetDispatchExPropertyFlags returns int, use …

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Copilot AI requested a review from AaronRobinsonMSFT March 23, 2026 22:50

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AaronRobinsonMSFT added this to the 11.0.0 milestone Mar 23, 2026

AaronRobinsonMSFT enabled auto-merge (squash) March 23, 2026 23:06

AaronRobinsonMSFT merged commit 63e88d1 into main Mar 24, 2026
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AaronRobinsonMSFT deleted the copilot/address-pending-feedback branch March 24, 2026 04:11

dotnet-maestro bot mentioned this pull request Mar 25, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#5691

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Convert more COM interop MethodDescCallSite to UnmanagedCallersOnly (UCO)#125849

Convert more COM interop MethodDescCallSite to UnmanagedCallersOnly (UCO)#125849
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Copilot AI commented Mar 20, 2026 •

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Copilot AI commented Mar 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

New UCO helpers in StubHelpers.cs

Feedback addressed

Dead code removed

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Pull request overview

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Copilot AI commented Mar 20, 2026 •

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New UCO helpers in `StubHelpers.cs`