Move IDispatch helpers into IDispatchHelpers.cs

[Copilot]

Cherry-picks am11@ae7563a (author: Adeel Mujahid / am11) which converts MethodDescCallSite to UCO in DispatchInfo, then moves all IDispatch helper methods into their own file.

Changes

• Cherry-picked commit ae7563a from am11/runtime with author preserved (Adeel Mujahid)
• Created src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/IDispatchHelpers.cs as a standalone internal static class IDispatchHelpers in the System.Runtime.InteropServices namespace, containing all IDispatch-related helpers:
  • Existing helpers moved from StubHelpers.cs: DispatchExPropertyCanRead/DispatchExPropertyCanWrite constants and GetDispatchExPropertyFlags
  • New helpers: GetDispatchParameterInfoName, GetDispatchMemberInfoName, GetDispatchMemberInfoType, HasDispatchCustomAttribute, GetDispatchMemberParameters, GetDispatchPropertyTokenAndModule, GetDispatchPropertyAccessor, GetDispatchFieldValue, SetDispatchFieldValue, GetDispatchPropertyValue, SetDispatchPropertyValue, InvokeDispatchMethodInfo, InvokeDispatchReflectMember, GetDispatchProperties, GetDispatchFields, GetDispatchMethods, GetDispatchInnerException
• Removed those methods from StubHelpers.cs
• Added IDispatchHelpers.cs to System.Private.CoreLib.csproj under the FeatureCominterop condition group (no #if FEATURE_COMINTEROP inside the file itself, as conditional compilation is handled by the project file)
• Updated corelib.h to define a new IDISPATCHHELPERS class entry (mapped to System.Runtime.InteropServices.IDispatchHelpers) and moved all dispatch-related DEFINE_METHOD registrations from STUBHELPERS to IDISPATCHHELPERS
• Updated dispatchinfo.cpp and stdinterfaces.cpp to use METHOD__IDISPATCHHELPERS__* method references instead of METHOD__STUBHELPERS__* for all IDispatch methods
• Consolidated all nested and consecutive GCPROTECT_BEGIN / GCPROTECT_END pairs in dispatchinfo.cpp into single struct-based GCPROTECT_BEGIN blocks using the standard anonymous-struct gc pattern
• In GetMemberProps() and SetUpParamMarshalerInfo(), replaced the GetDispatchMethodDesc and GetDispatchFieldDesc managed callbacks with direct native casts to REFLECTMETHODREF/REFLECTFIELDREF and calls to GetMethod()/GetField() — eliminating those two callbacks entirely
• Merged the GetDispatchPropertyToken and GetDispatchPropertyModule managed callbacks into a single GetDispatchPropertyTokenAndModule callback that returns both values in one call
• Changed GetDispatchMemberInfoType to return int directly (like GetDispatchExPropertyFlags) and updated its call site to use InvokeThrowing_Ret<INT32>
• Removed all [SupportedOSPlatform("windows")] annotations from IDispatchHelpers.cs and the now-unused using System.Runtime.Versioning;
• Cleaned up unused metasig entries in metasig.h (SM_PtrMethodBase_PtrIntPtr_PtrException_RetVoid, SM_PtrFieldInfo_PtrIntPtr_PtrException_RetVoid, SM_PtrPropertyInfo_PtrModule_PtrException_RetVoid, SM_PtrMember_PtrInt_PtrException_RetVoid, SM_PtrPropertyInfo_PtrInt_PtrException_RetVoid) and added replacements (SM_PtrMember_PtrException_RetInt, SM_PtrPropertyInfo_PtrInt_PtrModule_PtrException_RetVoid)

Note

This PR was created with AI assistance (GitHub Copilot).

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Pull request overview

This PR refactors CoreCLR COM interop dispatch support by moving IDispatch-related managed helpers out of StubHelpers into a dedicated System.Runtime.InteropServices.IDispatchHelpers type, and updates the VM to call these helpers via UnmanagedCallersOnlyCaller.

Changes:

• Introduces IDispatchHelpers.cs and migrates all IDispatch helper entrypoints from StubHelpers to the new type.
• Updates CoreCLR VM call sites (e.g., dispatchinfo.cpp, stdinterfaces.cpp) to use METHOD__IDISPATCHHELPERS__* instead of METHOD__STUBHELPERS__*.
• Extends corelib.h and metasig.h to register the new class and required metasigs; updates CoreLib project file inclusion under FeatureCominterop.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/coreclr/vm/stdinterfaces.cpp	Switches DispatchEx helper call to IDISPATCHHELPERS entrypoint.
src/coreclr/vm/metasig.h	Adds metasigs needed for new UCO helper signatures.
src/coreclr/vm/dispatchinfo.cpp	Replaces MethodDescCallSite usage with UnmanagedCallersOnlyCaller calls into IDispatchHelpers.
src/coreclr/vm/corelib.h	Registers new IDISPATCHHELPERS class and maps VM method IDs to the new managed helpers.
src/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs	Removes IDispatch helper(s) and adds RequiresUnsafe annotations to some UCO methods.
src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/IDispatchHelpers.cs	Adds new managed helper type with [UnmanagedCallersOnly] entrypoints for IDispatch interop.
src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj	Includes IDispatchHelpers.cs under FeatureCominterop.

[am11]

Looks good, I think it would need to resolve conflicts after @AaronRobinsonMSFT's PR is merged.

[jkotas]

/ba-g known issue dotnet/dnceng#6473 (no space left on device), not getting matched for some reason

[huoyaoyuan]

I was postponing DispatchInfo with #124423. The invokers could be moved to managed as well and reduce the interop boundary.

[am11]

The goal here is to get rid of MethodDescCallSite and this PR is dropping 31 of 58 remaining usages. Complete managed port can be done separately.