diff --git a/xcm/src/v1/README.md b/xcm/src/v1/README.md deleted file mode 100644 index 2985125b11a4..000000000000 --- a/xcm/src/v1/README.md +++ /dev/null @@ -1,25 +0,0 @@ -# XCM Version 1 -The comprehensive list of changes can be found in [this PR description](https://github.com/paritytech/polkadot/pull/2815#issue-608567900). - -## Changes to be aware of -Most changes should automatically be resolved via the conversion traits (i.e. `TryFrom` and `From`). The list here is mostly for incompatible changes that result in an `Err(())` when attempting to convert XCM objects from v0. - -### Junction -- `v0::Junction::Parent` cannot be converted to v1, because the way we represent parents in v1 has changed - instead of being a property of the junction, v1 MultiLocations now have an extra field representing the number of parents that the MultiLocation contains. - -### MultiLocation -- The `try_from` conversion method will always canonicalize the v0 MultiLocation before attempting to do the proper conversion. Since canonicalization is not a fallible operation, we do not expect v0 MultiLocation to ever fail to be upgraded to v1. - -### MultiAsset -- Stronger typing to differentiate between a single class of `MultiAsset` and several classes of `MultiAssets` is introduced. As the name suggests, a `Vec` that is used on all APIs will instead be using a new type called `MultiAssets` (note the `s`). -- All `MultiAsset` variants whose name contains "All" in it, namely `v0::MultiAsset::All`, `v0::MultiAsset::AllFungible`, `v0::MultiAsset::AllNonFungible`, `v0::MultiAsset::AllAbstractFungible`, `v0::MultiAsset::AllAbstractNonFungible`, `v0::MultiAsset::AllConcreteFungible` and `v0::MultiAsset::AllConcreteNonFungible`, will fail to convert to v1 MultiAsset, since v1 does not contain these variants. -- Similarly, all `MultiAsset` variants whose name contains "All" in it can be converted into a `WildMultiAsset`. -- `v0::MultiAsset::None` is not represented at all in v1. - -### XCM -- No special attention necessary - -### Order -- `v1::Order::DepositAsset` and `v1::Order::DepositReserveAsset` both introduced a new `max_asset` field that limits the maximum classes of assets that can be deposited. During conversion from v0, the `max_asset` field defaults to 1. -- v1 Orders that contain `MultiAsset` as argument(s) will need to explicitly specify the amount and details of assets. This is to prevent accidental misuse of `All` to possibly transfer, spend or otherwise perform unintended operations on `All` assets. -- v1 Orders that do allow the notion of `All` to be used as wildcards, will instead use a new type called `MultiAssetFilter`. diff --git a/xcm/src/v2/mod.rs b/xcm/src/v2/mod.rs index 60bec66ed963..444a6ae86811 100644 --- a/xcm/src/v2/mod.rs +++ b/xcm/src/v2/mod.rs @@ -14,7 +14,41 @@ // You should have received a copy of the GNU General Public License // along with Cumulus. If not, see . -//! Version 1 of the Cross-Consensus Message format data structures. +//! # XCM Version 2 +//! Version 2 of the Cross-Consensus Message format data structures. The comprehensive list of +//! changes can be found in +//! [this PR description](https://github.com/paritytech/polkadot/pull/3629#issue-968428279). +//! +//! ## Changes to be aware of +//! The biggest change here is the restructuring of XCM messages: instead of having `Order` and +//! `Xcm` types, the `Xcm` type now simply wraps a `Vec` containing `Instruction`s. However, most +//! changes should still be automatically convertible via the `try_from` and `from` conversion +//! functions. +//! +//! ### Junction +//! - No special attention necessary +//! +//! ### `MultiLocation` +//! - No special attention necessary +//! +//! ### `MultiAsset` +//! - No special attention necessary +//! +//! ### XCM and Order +//! - `Xcm` and `Order` variants are now combined under a single `Instruction` enum. +//! - `Order` is now obsolete and replaced entirely by `Instruction`. +//! - `Xcm` is now a simple wrapper around a `Vec`. +//! - During conversion from `Order` to `Instruction`, we do not handle `BuyExecution`s that have +//! nested XCMs, i.e. if the `instructions` field in the `BuyExecution` enum struct variant is +//! not empty, then the conversion will fail. To address this, rewrite the XCM using +//! `Instruction`s in chronological order. +//! - During conversion from `Xcm` to `Instruction`, we do not handle `RelayedFrom` messages at +//! all. +//! +//! ### XCM Pallet +//! - The `Weigher` configuration item must have sensible weights defined for `BuyExecution` and +//! `DepositAsset` instructions. Failing that, dispatch calls to `teleport_assets` and +//! `reserve_transfer_assets` will fail with `UnweighableMessage`. use super::v1::{Order as OldOrder, Response as OldResponse, Xcm as OldXcm}; use crate::{DoubleEncoded, GetWeight};