Failure to marshal out array of WinRT projected enum type

[TautvydasZilys]

Given this C++ WinRT Component:

// DurationTypeArrayLeakComponent.idl
import "inspectable.idl";
import "Windows.UI.Xaml.idl";

namespace DurationTypeArrayLeakComponent
{
    runtimeclass DurationTypeHelper;

    [exclusiveto(DurationTypeHelper)]
    [uuid(835C87D2-8484-4BD7-AD1C-6AE857BDD1FC), version(1.0)]
    interface IDurationTypeHelperStatics : IInspectable
    {
        HRESULT CopyDurationTypesArray([in] UINT32 inTypesSize, [in, size_is(inTypesSize)] Windows.UI.Xaml.DurationType* inTypes, [in] UINT32 outTypesSize, [out, size_is(outTypesSize)] Windows.UI.Xaml.DurationType* outTypes);
    }

    [version(1.0)]
    [static(IDurationTypeHelperStatics, 1.0)]
    runtimeclass DurationTypeHelper
    {
    }
}

// DurationTypeHelper.h
#pragma once

#include "DurationTypeArrayLeakComponent_h.h"
#include <wrl.h>

namespace ABI
{
    namespace DurationTypeArrayLeakComponent
    {
        class DurationTypeHelper :
            public Microsoft::WRL::ActivationFactory<IDurationTypeHelperStatics>
        {
            InspectableClassStatic(RuntimeClass_DurationTypeArrayLeakComponent_DurationTypeHelper, BaseTrust);

        public:
            DurationTypeHelper();

            virtual HRESULT STDMETHODCALLTYPE CopyDurationTypesArray(UINT32 inTypesSize, ABI::Windows::UI::Xaml::DurationType* inTypes, UINT32 outTypesSize, ABI::Windows::UI::Xaml::DurationType* outTypes) override;
        };
    }
}

// DurationTypeHelper.cpp
#include "DurationTypeHelper.h"

using namespace ABI::DurationTypeArrayLeakComponent;
using namespace ABI::Windows::Foundation;
using namespace ABI::Windows::UI::Xaml;

DurationTypeHelper::DurationTypeHelper()
{
}

HRESULT STDMETHODCALLTYPE DurationTypeHelper::CopyDurationTypesArray(UINT32 inTypesSize, DurationType* inTypes, UINT32 outTypesSize, DurationType* outTypes)
{
    if (inTypesSize != outTypesSize)
    {
        RoOriginateError(E_INVALIDARG, Microsoft::WRL::Wrappers::HStringReference(L"Array lengths must match.").Get());
        return E_INVALIDARG;
    }

    for (UINT32 i = 0; i < inTypesSize; i++)
        outTypes[i] = inTypes[i];

    return S_OK;
}

ActivatableStaticOnlyFactory(DurationTypeHelper)

This C# code throws exception on CoreCLR (and desktop .NET too):

using DurationTypeArrayLeakComponent;
using System;
using Windows.UI.Xaml;

namespace DurationTypeArrayLeak
{
    class Program
    {
        static void Main()
        {
            var types = new DurationType[]
            {
                DurationType.Automatic,
                DurationType.Forever,
                DurationType.TimeSpan,
                DurationType.Forever,
                DurationType.Automatic,
                DurationType.TimeSpan
            };

            var typesCopy = new DurationType[types.Length];
            DurationTypeHelper.CopyDurationTypesArray(types, typesCopy);

            for (int i = 0; i < types.Length; i++)
            {
                if (types[i] != typesCopy[i])
                    throw new Exception("Type was not copied correctly.");
            }
        }
    }
}

Full repro project: DurationTypeArrayLeak.zip

This doesn't happen on .NET Native. It seems the source of the problem is that the JIT passes 0 as array element size to MngdHiddenLengthArrayMarshaler::CreateMarshaler:

00007FFA4DB92BED  lea         rbx,[rsp+40h]  
00007FFA4DB92BF2  mov         qword ptr [rbp+90h],rsp  
00007FFA4DB92BF9  mov         rcx,rbx  
00007FFA4DB92BFC  mov         rdx,7FFAE9A3A9F8h  
00007FFA4DB92C06  xor         r8d,r8d  // <-------- here's the issue. Size should be 4.
00007FFA4DB92C09  mov         r9d,0FCh  
00007FFA4DB92C0F  call        MngdHiddenLengthArrayMarshaler::CreateMarshaler (07FFAAD10EEA0h)

[RussKeldorph]

Starting with area-CodeGen bug please update if area-Interop or something else.

@jeffschwMSFT

[jkotas]

This is interop bug

[AaronRobinsonMSFT]

WinRT scenarios have changed substantial in .NET 5.0. WinRT support in .NET 5.0 should look to the https://aka.ms/cswinrt toolset.