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xcm-builder: PayOverXcm supports fallible convertors for asset kind a…
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…nd beneficiary conversion (#1572)

`PayOverXcm` type accepts two converters to transform the `AssetKind`
and `Beneficiary` parameter types into recognized `xcm` types. In this
PR, we've modified the bounds for these converters, transitioning from
`Convert` to `TryConvert`.

One such use case for this adjustment is when dealing with versioned xcm
types for `AssetKind` and `Beneficiary`. These types might be not
convertible to the latest xcm version, hence the need for fallible
conversion.

This changes required for
#1333
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muharem authored Sep 18, 2023
1 parent e389988 commit a8e82a3
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Showing 3 changed files with 17 additions and 15 deletions.
8 changes: 4 additions & 4 deletions polkadot/xcm/xcm-builder/src/location_conversion.rs
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ use crate::universal_exports::ensure_is_remote;
use frame_support::traits::Get;
use parity_scale_codec::{Compact, Decode, Encode};
use sp_io::hashing::blake2_256;
use sp_runtime::traits::{AccountIdConversion, Convert, TrailingZeroInput};
use sp_runtime::traits::{AccountIdConversion, TrailingZeroInput, TryConvert};
use sp_std::{marker::PhantomData, prelude::*};
use xcm::latest::prelude::*;
use xcm_executor::traits::ConvertLocation;
Expand Down Expand Up @@ -322,10 +322,10 @@ impl<Network: Get<Option<NetworkId>>, AccountId: From<[u8; 32]> + Into<[u8; 32]>
/// network (provided by `Network`) and the `AccountId`'s `[u8; 32]` datum for the `id`.
pub struct AliasesIntoAccountId32<Network, AccountId>(PhantomData<(Network, AccountId)>);
impl<'a, Network: Get<Option<NetworkId>>, AccountId: Clone + Into<[u8; 32]> + Clone>
Convert<&'a AccountId, MultiLocation> for AliasesIntoAccountId32<Network, AccountId>
TryConvert<&'a AccountId, MultiLocation> for AliasesIntoAccountId32<Network, AccountId>
{
fn convert(who: &AccountId) -> MultiLocation {
AccountId32 { network: Network::get(), id: who.clone().into() }.into()
fn try_convert(who: &AccountId) -> Result<MultiLocation, &AccountId> {
Ok(AccountId32 { network: Network::get(), id: who.clone().into() }.into())
}
}

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18 changes: 10 additions & 8 deletions polkadot/xcm/xcm-builder/src/pay.rs
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ use frame_support::traits::{
tokens::{Pay, PaymentStatus},
Get,
};
use sp_runtime::traits::Convert;
use sp_runtime::traits::TryConvert;
use sp_std::{marker::PhantomData, vec};
use xcm::{opaque::lts::Weight, prelude::*};
use xcm_executor::traits::{QueryHandler, QueryResponseStatus};
Expand Down Expand Up @@ -71,8 +71,8 @@ impl<
Timeout: Get<Querier::BlockNumber>,
Beneficiary: Clone,
AssetKind,
AssetKindToLocatableAsset: Convert<AssetKind, LocatableAssetId>,
BeneficiaryRefToLocation: for<'a> Convert<&'a Beneficiary, MultiLocation>,
AssetKindToLocatableAsset: TryConvert<AssetKind, LocatableAssetId>,
BeneficiaryRefToLocation: for<'a> TryConvert<&'a Beneficiary, MultiLocation>,
> Pay
for PayOverXcm<
Interior,
Expand All @@ -96,12 +96,14 @@ impl<
asset_kind: Self::AssetKind,
amount: Self::Balance,
) -> Result<Self::Id, Self::Error> {
let locatable = AssetKindToLocatableAsset::convert(asset_kind);
let locatable = AssetKindToLocatableAsset::try_convert(asset_kind)
.map_err(|_| xcm::latest::Error::InvalidLocation)?;
let LocatableAssetId { asset_id, location: asset_location } = locatable;
let destination = Querier::UniversalLocation::get()
.invert_target(&asset_location)
.map_err(|()| Self::Error::LocationNotInvertible)?;
let beneficiary = BeneficiaryRefToLocation::convert(&who);
let beneficiary = BeneficiaryRefToLocation::try_convert(&who)
.map_err(|_| xcm::latest::Error::InvalidLocation)?;

let query_id = Querier::new_query(asset_location, Timeout::get(), Interior::get());

Expand Down Expand Up @@ -196,10 +198,10 @@ pub struct LocatableAssetId {
/// Adapter `struct` which implements a conversion from any `AssetKind` into a [`LocatableAssetId`]
/// value using a fixed `Location` for the `location` field.
pub struct FixedLocation<Location>(sp_std::marker::PhantomData<Location>);
impl<Location: Get<MultiLocation>, AssetKind: Into<AssetId>> Convert<AssetKind, LocatableAssetId>
impl<Location: Get<MultiLocation>, AssetKind: Into<AssetId>> TryConvert<AssetKind, LocatableAssetId>
for FixedLocation<Location>
{
fn convert(value: AssetKind) -> LocatableAssetId {
LocatableAssetId { asset_id: value.into(), location: Location::get() }
fn try_convert(value: AssetKind) -> Result<LocatableAssetId, AssetKind> {
Ok(LocatableAssetId { asset_id: value.into(), location: Location::get() })
}
}
6 changes: 3 additions & 3 deletions polkadot/xcm/xcm-builder/src/tests/pay/pay.rs
Original file line number Diff line number Diff line change
Expand Up @@ -29,9 +29,9 @@ pub struct AssetKind {
}

pub struct LocatableAssetKindConverter;
impl sp_runtime::traits::Convert<AssetKind, LocatableAssetId> for LocatableAssetKindConverter {
fn convert(value: AssetKind) -> LocatableAssetId {
LocatableAssetId { asset_id: value.asset_id, location: value.destination }
impl sp_runtime::traits::TryConvert<AssetKind, LocatableAssetId> for LocatableAssetKindConverter {
fn try_convert(value: AssetKind) -> Result<LocatableAssetId, AssetKind> {
Ok(LocatableAssetId { asset_id: value.asset_id, location: value.destination })
}
}

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