mut Specifier is specified but is not respected in all cases

[jayrulez]

This example fails to compile:

using System;
[CRepr]
struct IUnknown
{
    public new const Guid IID = .(0x00000000, 0x0000, 0x0000, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);

    public VTable* VT { get => (.)mVT; }

    protected VTable* mVT;

    [CRepr]public struct VTable
    {
        protected new function [CallingConvention(.Stdcall)] System.Windows.COM_IUnknown.HResult(SelfOuter* self, in Guid riid, void** ppvObject) QueryInterface;
        protected new function [CallingConvention(.Stdcall)] uint32(SelfOuter* self) AddRef;
        protected new function [CallingConvention(.Stdcall)] uint32(SelfOuter* self) Release;
    }


    public System.Windows.COM_IUnknown.HResult QueryInterface(in Guid riid, void** ppvObject) mut => VT.[Friend]QueryInterface(&this, riid, ppvObject);

    public uint32 AddRef() mut => VT.[Friend]AddRef(&this);

    public uint32 Release() mut => VT.[Friend]Release(&this);
}

struct COMPtr<T> : IDisposable where T : IUnknown
{
    private T* m_ComPtr = null;

    public void Dispose() mut
    {
        m_ComPtr.Release();
    }
}