FArchive::TotalSize returns -1

Hello,

I’m not sure if this is intended to happen but using FArchive within NetSerialize has no information about the current size written/available, this renders a few features useless such as compressing. Also calling SerializeCompressed at this point would cause a crash because its attempting to allocate -1 as unsigned 64 bit type, go figure.

Will this be implemented or is it left out on purpose?