Linear collection marshallers will generate calls to GetUnmanagedValuesDestination for 'out' variables during cleanup in ManagedToUnmanaged

[jtschuster]

According to https://github.com/dotnet/runtime/blob/main/docs/design/libraries/LibraryImportGenerator/UserTypeMarshallingV2.md#stateless-unmanaged-managed-1, it is not required to have this method since the value is only marshalled from unmanaged to managed. The unmarshal stage uses GetUnmanagedValuesSource, which cleanup should use as well.

The method

        void MethodOut(
            [MarshalUsing(CountElementName = nameof(size))] out StatelessCollection<StatelessType> pOut,
            out int size);

    void global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement.MethodOut(out global::SharedTypes.ComInterfaces.StatelessCollection<global::SharedTypes.ComInterfaces.StatelessType> pOut, out int size)
    {
        var(__this, __vtable_native) = ((System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement));
        bool __invokeSucceeded = default;
        System.Runtime.CompilerServices.Unsafe.SkipInit(out pOut);
        System.Runtime.CompilerServices.Unsafe.SkipInit(out size);
        nint __pOut_native = default;
        int __invokeRetVal = default;
        // Setup - Perform required setup.
        int __pOut_native__numElements;
        System.Runtime.CompilerServices.Unsafe.SkipInit(out __pOut_native__numElements);
        try
        {
            // Pin - Pin data in preparation for calling the P/Invoke.
            fixed (int* __size_native = &size)
            {
                __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, nint*, int*, int> )__vtable_native[6])(__this, &__pOut_native, __size_native);
            }

            __invokeSucceeded = true;
            System.GC.KeepAlive(this);
            // Unmarshal - Convert native data to managed data.
            System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
            __pOut_native__numElements = size;
            pOut = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.AllocateContainerForManagedElements(__pOut_native, __pOut_native__numElements);
            {
                System.ReadOnlySpan<nint> __pOut_native__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetUnmanagedValuesSource(__pOut_native, __pOut_native__numElements);
                System.Span<global::SharedTypes.ComInterfaces.StatelessType> __pOut_native__managedSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetManagedValuesDestination(pOut);
                for (int __i0 = 0; __i0 < __pOut_native__numElements; ++__i0)
                {
                    __pOut_native__managedSpan[__i0] = global::SharedTypes.ComInterfaces.StatelessTypeMarshaller.ConvertToManaged(__pOut_native__nativeSpan[__i0]);
                }
            }
        }
        finally
        {
            if (__invokeSucceeded)
            {
                // CleanupCalleeAllocated - Perform cleanup of callee allocated resources.
                {
// ISSUE HERE
                    // Should call GetUnmanagedValuesSource
                    System.ReadOnlySpan<nint> __pOut_native__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetUnmanagedValuesDestination(__pOut_native, __pOut_native__numElements);
                    for (int __i0 = 0; __i0 < __pOut_native__nativeSpan.Length; ++__i0)
                    {
                        global::SharedTypes.ComInterfaces.StatelessTypeMarshaller.Free(__pOut_native__nativeSpan[__i0]);
                    }
                }

                __pOut_native__numElements = size;
                global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.Free(__pOut_native);
            }
        }
    }

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Issue Details

---

According to https://github.com/dotnet/runtime/blob/main/docs/design/libraries/LibraryImportGenerator/UserTypeMarshallingV2.md#stateless-unmanaged-managed-1, it is not required to have this method since the value is only marshalled from unmanaged to managed. The unmarshal stage uses GetUnmanagedValuesSource, which cleanup should use as well.

The method

        void MethodOut(
            [MarshalUsing(CountElementName = nameof(size))] out StatelessCollection<StatelessType> pOut,
            out int size);

    void global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement.MethodOut(out global::SharedTypes.ComInterfaces.StatelessCollection<global::SharedTypes.ComInterfaces.StatelessType> pOut, out int size)
    {
        var(__this, __vtable_native) = ((System.Runtime.InteropServices.Marshalling.IUnmanagedVirtualMethodTableProvider)this).GetVirtualMethodTableInfoForKey(typeof(global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement));
        bool __invokeSucceeded = default;
        System.Runtime.CompilerServices.Unsafe.SkipInit(out pOut);
        System.Runtime.CompilerServices.Unsafe.SkipInit(out size);
        nint __pOut_native = default;
        int __invokeRetVal = default;
        // Setup - Perform required setup.
        int __pOut_native__numElements;
        System.Runtime.CompilerServices.Unsafe.SkipInit(out __pOut_native__numElements);
        try
        {
            // Pin - Pin data in preparation for calling the P/Invoke.
            fixed (int* __size_native = &size)
            {
                __invokeRetVal = ((delegate* unmanaged[MemberFunction]<void*, nint*, int*, int> )__vtable_native[6])(__this, &__pOut_native, __size_native);
            }

            __invokeSucceeded = true;
            System.GC.KeepAlive(this);
            // Unmarshal - Convert native data to managed data.
            System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(__invokeRetVal);
            __pOut_native__numElements = size;
            pOut = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.AllocateContainerForManagedElements(__pOut_native, __pOut_native__numElements);
            {
                System.ReadOnlySpan<nint> __pOut_native__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetUnmanagedValuesSource(__pOut_native, __pOut_native__numElements);
                System.Span<global::SharedTypes.ComInterfaces.StatelessType> __pOut_native__managedSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetManagedValuesDestination(pOut);
                for (int __i0 = 0; __i0 < __pOut_native__numElements; ++__i0)
                {
                    __pOut_native__managedSpan[__i0] = global::SharedTypes.ComInterfaces.StatelessTypeMarshaller.ConvertToManaged(__pOut_native__nativeSpan[__i0]);
                }
            }
        }
        finally
        {
            if (__invokeSucceeded)
            {
                // CleanupCalleeAllocated - Perform cleanup of callee allocated resources.
                {
// ISSUE HERE
                    // Should call GetUnmanagedValuesSource
                    System.ReadOnlySpan<nint> __pOut_native__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.GetUnmanagedValuesDestination(__pOut_native, __pOut_native__numElements);
                    for (int __i0 = 0; __i0 < __pOut_native__nativeSpan.Length; ++__i0)
                    {
                        global::SharedTypes.ComInterfaces.StatelessTypeMarshaller.Free(__pOut_native__nativeSpan[__i0]);
                    }
                }

                __pOut_native__numElements = size;
                global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.Default.Free(__pOut_native);
            }
        }
    }

Author:	jtschuster
Assignees:	-
Labels:	area-System.Runtime.InteropServices
Milestone:	-