Implement holds and freezes in orml-tokens.

[TorstenStueber]

The latest Polkadot release (v0.9.42) added two new traits to the Fungibles family: hold and freeze (which has been added in paritytech/substrate#12951).

It would be very helpful if the tokens pallet also implement this additional Fungibles traits. At least for the hold trait it should be possible to use the underlying reserve mechanism.

[Chralt98]

Regarding holds and freezes: Will anything change for the interface of orml_currencies? Or is it completely abstracted away and we can use reserve_named and unreserve_named and set_lock, extend_lock and remove_lock in the future?

[xlc]

fungibles traits are implemented

Current interface is not impacted.

[TorstenStueber]

fungibles traits are implemented

@xlc This issue is specifically about Fungibles::InspectFreeze, Fungibles::InspectHold, etc. (three more, see here).

To my knowledge they are not implemented yet.

[wischli]

I'd like to add that the fn reducible_balance impl of orml-tokens seems to diverge from frame (both for fungible, i.e. pallet-balances as well as fungibles, i.e. pallet-assets:

For orml-tokens, the only case considering subtracting ED from the liquid funds is Preservation::Protect whereas in frame this can also occur for other preservations with Preservation::Preserve being the most protected one:

orml-tokens

open-runtime-module-library/tokens/src/lib.rs

Line 1809 in 83a76c2

if frame_system::Pallet::<T>::can_dec_provider(who) && !matches!(preservation, Preservation::Protect) {

pallet-balances

https://github.com/paritytech/polkadot-sdk/blob/3ae86ae075ac5eb9b80f89f09bd7f4a63f97c582/substrate/frame/balances/src/impl_fungible.rs#L57-L67

pallet-assets

https://github.com/paritytech/polkadot-sdk/blob/3ae86ae075ac5eb9b80f89f09bd7f4a63f97c582/substrate/frame/assets/src/impl_fungibles.rs#L58-L59