[ComInterfaceGenerator] PreserveSig with collection return type will not properly marshal back to caller #89893
Description
This is probably not a realistic situation, but we may want to fix it or warn when the [PreserveSig] return value unmarshaller doesn't take an int as the unmanaged type.
This method definition
[PreserveSig]
[return: MarshalUsing(CountElementName = nameof(size))]
StatelessCollection<StatelessType> ReturnPreserveSig(int size);will generate this unmanaged to managed method
internal static global::SharedTypes.ComInterfaces.NativeCollection<global::SharedTypes.ComInterfaces.StatelessType> ABI_ReturnPreserveSig(System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int size)
{
global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement @this = default;
global::SharedTypes.ComInterfaces.StatelessCollection<global::SharedTypes.ComInterfaces.StatelessType> __retVal = default;
global::SharedTypes.ComInterfaces.NativeCollection<global::SharedTypes.ComInterfaces.StatelessType> __retVal_native = default;
// Setup - Perform required setup.
int __retVal_native__numElements;
System.Runtime.CompilerServices.Unsafe.SkipInit(out __retVal_native__numElements);
try
{
// Unmarshal - Convert native data to managed data.
@this = System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement>(__this_native);
__retVal = @this.ReturnPreserveSig(size);
// Marshal - Convert managed data to native data.
__retVal_native = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.AllocateContainerForUnmanagedElements(__retVal, out __retVal_native__numElements);
{
System.ReadOnlySpan<global::SharedTypes.ComInterfaces.StatelessType> __retVal_native__managedSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.GetManagedValuesSource(__retVal);
System.Span<nint> __retVal_native__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.GetUnmanagedValuesDestination(__retVal_native, __retVal_native__numElements);
__retVal_native__nativeSpan.Clear();
; // Should be a for loop here that marshals elements
}
}
catch (System.Exception __exception)
{
__retVal_native = System.Runtime.InteropServices.Marshalling.ExceptionAsDefaultMarshaller<global::SharedTypes.ComInterfaces.NativeCollection<global::SharedTypes.ComInterfaces.StatelessType>>.ConvertToUnmanaged(__exception);
}
return __retVal_native;
}For comparison, a regular managed return value
[return: MarshalUsing(CountElementName = nameof(size))]
StatelessCollection<StatelessType> Return(int size);Generates this unmanaged to managed stub
internal static int ABI_Return(System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch* __this_native, int size, global::SharedTypes.ComInterfaces.NativeCollection<global::SharedTypes.ComInterfaces.StatelessType>* __invokeRetValUnmanaged__param)
{
global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement @this = default;
ref global::SharedTypes.ComInterfaces.NativeCollection<global::SharedTypes.ComInterfaces.StatelessType> __invokeRetValUnmanaged = ref *__invokeRetValUnmanaged__param;
global::SharedTypes.ComInterfaces.StatelessCollection<global::SharedTypes.ComInterfaces.StatelessType> __invokeRetVal = default;
int __retVal = default;
// Setup - Perform required setup.
int __invokeRetValUnmanaged__numElements;
System.Runtime.CompilerServices.Unsafe.SkipInit(out __invokeRetValUnmanaged__numElements);
try
{
// Unmarshal - Convert native data to managed data.
__retVal = 0; // S_OK
@this = System.Runtime.InteropServices.ComWrappers.ComInterfaceDispatch.GetInstance<global::SharedTypes.ComInterfaces.IStatelessCollectionStatelessElement>(__this_native);
__invokeRetVal = @this.Return(size);
// Marshal - Convert managed data to native data.
__invokeRetValUnmanaged = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.AllocateContainerForUnmanagedElements(__invokeRetVal, out __invokeRetValUnmanaged__numElements);
{
System.ReadOnlySpan<global::SharedTypes.ComInterfaces.StatelessType> __invokeRetValUnmanaged__managedSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.GetManagedValuesSource(__invokeRetVal);
System.Span<nint> __invokeRetValUnmanaged__nativeSpan = global::SharedTypes.ComInterfaces.StatelessCollectionMarshaller<global::SharedTypes.ComInterfaces.StatelessType, nint>.ManagedToUnmanaged.GetUnmanagedValuesDestination(__invokeRetValUnmanaged, __invokeRetValUnmanaged__numElements);
__invokeRetValUnmanaged__nativeSpan.Clear();
for (int __i0 = 0; __i0 < __invokeRetValUnmanaged__managedSpan.Length; ++__i0)
{
__invokeRetValUnmanaged__nativeSpan[__i0] = global::SharedTypes.ComInterfaces.StatelessTypeMarshaller.ManagedToUnmanaged.ConvertToUnmanaged(__invokeRetValUnmanaged__managedSpan[__i0]);
}
}
}
catch (System.Exception __exception)
{
__retVal = System.Runtime.InteropServices.Marshalling.ExceptionAsHResultMarshaller<int>.ConvertToUnmanaged(__exception);
}
return __retVal;
}