Would be nice if it were possible to call decode_len on an unbounded BTreeSet. Is there a limitation that makes this impossible atm?
No response
Where do you want to use this? BTreeSet is not a storage item where we would normally need decode_len.
Ah, I see we have impl<T: Encode> StorageDecodeLength for Vec<T> {}, so it could be done analogous for BTreeSet.
What I meant was that there is no StorageBTreeSet type, only BoundedBTreeSet. So if you want to decode the length of a StorageValue<BTreeSet>, you already have the whole thing fetched and have no PoV gain from using decode_len.
