type synonym involving nat causes c++ compiler failure

[tjhance]

I have this type declared for some ghost code:

type FullMap<K(!new)> = m : imap<K, nat> | IsFull(m) && HasFiniteSupport(m) 

dafny c++ tries to compile it and, of course, complains (because of the nat). This type is only used in proof code, but there's no way to add a 'ghost' modifier to this declaration

[tjhance]

Here's a workaround:

type FullMap<K(!new)> = FM(ghost m: imap<K, nat>) ...