namespace System.Runtime.InteropServices.Marshalling
{
    [CustomMarshaller(typeof(GenericPlaceholder), MarshalMode.ManagedToUnmanagedIn, typeof(ManagedToUnmanagedIn))]
    [CustomMarshaller(typeof(GenericPlaceholder), MarshalMode.ManagedToUnmanagedOut, typeof(ManagedToUnmanagedOut))]
    [CustomMarshaller(typeof(GenericPlaceholder), MarshalMode.ManagedToUnmanagedRef, typeof(ManagedToUnmanagedRef))]
    public static class SafeHandleMarshaller<T>
        where T, SafeHandle!
    {
        public struct ManagedToUnmanagedRef
        {
            public void Free();
        }
    }
}