# Context

Estimating fees for XCM execution and sending has been an area with bad
UX.
The addition of the
[XcmPaymentApi](https://github.com/paritytech/polkadot-sdk/pull/3607)
exposed the necessary components to be able to estimate XCM fees
correctly, however, that was not the full story.
The `XcmPaymentApi` works for estimating fees only if you know the
specific XCM you want to execute or send.
This is necessary but most UIs want to estimate the fees for extrinsics,
they don't necessarily know the XCM program that's executed by them.

# Main addition

A new runtime API is introduced, the `XcmDryRunApi`, that given an
extrinsic, or an XCM program, returns its effects:
- Execution result
- Local XCM (in the case of an extrinsic)
- Forwarded XCMs
- List of events

This API can be used on its own for dry-running purposes, for
double-checking or testing, but it mainly shines when used in
conjunction with the `XcmPaymentApi`.
UIs can use these two APIs to estimate transfers.

# How it works

New tests are added to exemplify how to incorporate both APIs.
There's a mock test just to make sure everything works under
`xcm-fee-payment-runtime-api`.
There's a real-world test using Westend and AssetHubWestend under
`cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-westend/src/tests/xcm_fee_estimation.rs`.
Added both a test for a simple teleport between chains and a reserve
transfer asset between two parachains going through a reserve.

The steps to follow:
- Use `XcmDryRunApi::dry_run_extrinsic` to get local XCM program and
forwarded messages
- For each forwarded message
- Use `XcmPaymentApi::query_delivery_fee` LOCALLY to get the delivery
fees
- Use `XcmPaymentApi::query_xcm_weight` ON THE DESTINATION to get the
remote execution weight
- (optional) Use `XcmPaymentApi::query_acceptable_payment_assets` ON THE
DESTINATION to know on which assets the execution fees can be paid
- Use `XcmPaymentApi::query_weight_to_asset_fee` ON THE DESTINATION to
convert weight to the actual remote execution fees
- Use `XcmDryRunApi::dry_run_xcm` ON THE DESTINATION to know if a new
message will be forwarded, if so, continue

# Dear reviewer

The changes in this PR are grouped as follows, and in order of
importance:
- Addition of new runtime API
- Definition, mock and simple tests:
polkadot/xcm/xcm-fee-payment-runtime-api/*
- Implemented on Westend, Asset Hub Westend and Penpal, will implement
on every runtime in a following PR
- Addition of a new config item to the XCM executor for recording xcms
about to be executed
  - Definition: polkadot/xcm/xcm-executor/*
  - Implementation: polkadot/xcm/pallet-xcm/*
- had to update all runtime xcm_config.rs files with `type XcmRecorder =
XcmPallet;`
- Addition of a new trait for inspecting the messages in queues
  - Definition: polkadot/xcm/xcm-builder/src/routing.rs
  - Implemented it on all routers:
    - ChildParachainRouter: polkadot/runtime/common/src/xcm_sender.rs
- ParentAsUmp: cumulus/primitives/utility/src/lib.rs (piggybacked on
implementation in cumulus/pallets/parachain-system/src/lib.rs)
    - XcmpQueue: cumulus/pallets/xcmp-queue/src/lib.rs
    - Bridge: bridges/modules/xcm-bridge-hub-router/src/lib.rs
- More complicated and useful tests:
-
cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-westend/src/tests/xcm_fee_estimation.rs

## Next steps

With this PR, Westend, AssetHubWestend, Rococo and AssetHubRococo have
the new API.
UIs can test on these runtimes to create better experiences around
cross-chain operations.

Next:
- Add XcmDryRunApi to all system parachains
- Integrate xcm fee estimation in all emulated tests
- Get this on the fellowship runtimes

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

Closes: https://github.com/paritytech/polkadot-sdk/issues/4003 (please
see for the problem description)

## TODO
- [x] add more tests covering `WrapVersion` corner cases (e.g. para has
lower version, ...)
- [x] regenerate benchmarks `runtime_parachains::hrmp` (fix for Rococo
is here: https://github.com/paritytech/polkadot-sdk/pull/4332)

## Questions / possible improvements
- [ ] A `WrapVersion` implementation for `pallet_xcm` initiates version
discovery with
[note_unknown_version](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/pallet-xcm/src/lib.rs#L2527C5-L2527C25),
there is possibility to avoid this overhead in this HRMP case to create
new `WrapVersion` adapter for `pallet_xcm` which would not use
`note_unknown_version`. Is it worth to do it or not?
- [ ] There's a possibility to decouple XCM functionality from the HRMP
pallet, allowing any relay chain to generate its own notifications. This
approach wouldn't restrict notifications solely to the XCM. However,
it's uncertain whether it's worthwhile or desirable to do so? It means
making HRMP pallet more generic. E.g. hiding HRMP notifications behind
some trait:
	```
	trait HrmpNotifications {

		fn on_channel_open_request(
			sender: ParaId,
			proposed_max_capacity: u32,
			proposed_max_message_size: u32) -> primitives::DownwardMessage;

fn on_channel_accepted(recipient: ParaId) ->
primitives::DownwardMessage;

fn on_channel_closing(initiator: ParaId, sender: ParaId, recipient:
ParaId) -> primitives::DownwardMessage;
	}
	```
and then we could have whatever adapter, `impl HrmpNotifications for
VersionedXcmHrmpNotifications {...}`,
	```
	impl parachains_hrmp::Config for Runtime {
	..
		type HrmpNotifications = VersionedXcmHrmpNotifications;
	..
	}
	```

---------

Co-authored-by: command-bot <>
Co-authored-by: Bastian Köcher <git@kchr.de>

Split from #4374

This PR helps to reduce dependencies and align versions, which would
help to move them to workspace dep

This PR:
- changes `xcm::v4` to `xcm::prelude` imports for coretime stuff
- changes `query_acceptable_payment_assets` /
`query_weight_to_asset_fee` implementations to be more resilient to the
XCM version change
- adds `xcm_fee_payment_runtime_api::XcmPaymentApi` to the
AssetHubRococo/Westend exposing a native token as acceptable payment
asset

Continuation of: https://github.com/paritytech/polkadot-sdk/pull/3607

Closes: https://github.com/paritytech/polkadot-sdk/issues/4297

## Possible follow-ups

- [ ] add all sufficient assets (`Assets`, `ForeignAssets`) as
acceptable payment assets ?

This PR does a "developer experience" refactor of the XCM Simulator
Example.

I was looking for existing code / documentation where developers could
better learn about working with and configuring XCM.

The XCM Simulator was a natural starting point due to the fact that it
can emulate end to end XCM scenarios, without needing to spawn multiple
real chains.

However, the XCM Simulator Example was just 3 giant files with a ton of
configurations, runtime, pallets, and tests mashed together.

This PR breaks down the XCM Simulator Example in a way that I believe is
more approachable by a new developer who is looking to navigate the
various components of the end to end example, and modify it themselves.

The basic structure is:

- xcm simulator example
    - lib (tries to only use the xcm simulator macros)
    - tests
    - relay-chain
        - mod (basic runtime that developers should be familiar with)
        - xcm-config
            - mod (contains the `XcmConfig` type...

# ISSUE
- Link to issue: https://github.com/paritytech/polkadot-sdk/issues/4237

# DESCRIPTION
Remove all ModuleError with hard-coded indices to pallet Error. For
example:
```rs
Err(DispatchError::Module(ModuleError {
	index: 4,
	error: [2, 0, 0, 0],
	message: Some("Filtered")
}))
```
To 
```rs
let expected_result = Err(crate::Error::<Test>::Filtered.into());
assert_eq!(result, expected_result);
```
# TEST OUTCOME
```
test result: ok. 74 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.02s
```

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

Some traits are already included in the 2021 prelude and so shouldn't be
needed to use explicitly:

use `convert::TryFrom`, `convert::TryInto`, and `iter::FromIterator` are
removed.

( https://doc.rust-lang.org/core/prelude/rust_2021/ )

No breaking changes or change of functionality, so I think no PR doc is
needed in this case.

(Motivation: Removes some references to `sp-std`)

Changes:
- Add new error variant `ProcessMessageError::StackLimitReached` and
treat XCM error `ExceedsStackLimit` as such.

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>

Revert "pallet-xcm: Deprecate `execute` and `send` in favor of
`execute_blob` and `send_blob` (#3749)"

This reverts commit feee773d

.

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Javier Bullrich <javier@bullrich.dev>

This PR:
- introduces `AllowHrmpNotificationsFromRelayChain` barrier for allowing
HRMP notifications just from the relay chain (to fulfill safety
assumptions -
[see](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/src/v4/mod.rs#L532))
- sets it up for all testnet SP parachains

Continuation of: https://github.com/paritytech/polkadot-sdk/pull/3696

Change `transfer_assets_using_type()` to not assume `DepositAssets` as
the intended use of the assets on the destination.

Instead provides the caller with the ability to specify custom XCM that
be executed on `dest` chain as the last step of the transfer, thus
allowing custom usecases for the transferred assets. E.g. some are
used/swapped/etc there, while some are sent further to yet another
chain.

Note: this is a follow-up on
https://github.com/paritytech/polkadot-sdk/pull/3695, bringing in an API
change for `transfer_assets_using_type()`. This is ok as the previous
version has not been yet released. Thus, its first release will include
the new API proposed by this PR.

This allows usecases such as:
https://forum.polkadot.network/t/managing-sas-on-multiple-reserve-chains-for-same-asset/7538/4

BTW: all this pallet-xcm asset transfers code will be massively reduced
once we have https://github.com/paritytech/xcm-format/pull/54

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>

Ensure outbound XCMs are decodable with limits + add `EnsureDecodableXcm` router (for testing purposes) (#4186)

This PR:
- adds `EnsureDecodableXcm` (testing) router that attempts to *encode*
and *decode* passed XCM `message` to ensure that the receiving side will
be able to decode, at least with the same XCM version.
- fixes `pallet_xcm` / `pallet_xcm_benchmarks` assets data generation

Relates to investigation of
https://substrate.stackexchange.com/questions/11288 and missing fix
https://github.com/paritytech/polkadot-sdk/pull/2129 which did not get
into the fellows 1.1.X release.

## Questions/TODOs

- [x] fix XCM benchmarks, which produces undecodable data - new router
catched at least two cases
  - `BoundedVec exceeds its limit`
  - `Fungible asset of zero amount is not allowed`  
- [x] do we need to add `sort` to the `prepend_with` as we did for
reanchor [here](https://github.com/paritytech/polkadot-sdk/pull/2129)?
@serban300 (**created separate/follow-up PR**:
https://github.com/paritytech/polkadot-sdk/pull/4235)
- [x] We added decoding check to `XcmpQueue` -> `validate_xcm_nesting`,
why not to added to the `ParentAsUmp` or `ChildParachainRouter`?
@franciscoaguirre

 (**created separate/follow-up PR**:
https://github.com/paritytech/polkadot-sdk/pull/4236)
- [ ] `SendController::send_blob` replace `VersionedXcm::<()>::decode(`
with `VersionedXcm::<()>::decode_with_depth_limit(MAX_XCM_DECODE_DEPTH,
data)` ?

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

This PR:
- moves `validate_xcm_nesting` from `XcmpQueue` into the `VersionedXcm`
- adds `validate_xcm_nesting` to the `ParentAsUmp`
- adds `validate_xcm_nesting` to the `ChildParachainRouter`


Based on discussion
[here](https://github.com/paritytech/polkadot-sdk/pull/4186#discussion_r1571344270)
and/or
[here](https://github.com/paritytech/polkadot-sdk/pull/4186#discussion_r1572076666)
and/or [here]()

## Question/TODO

- [x] To the
[comment](https://github.com/paritytech/polkadot-sdk/pull/4186#discussion_r1572072295)
- Why was `validate_xcm_nesting` added just to the `XcmpQueue` router
and nowhere else? What kind of problem `MAX_XCM_DECODE_DEPTH` is
solving? (see
[comment](https://github.com/paritytech/polkadot-sdk/pull/4236#discussion_r1574605191))

This PR:
- sanitizes all `UniversalLocation`s with `GlobalConsensus` (when
possible) - addressing
[comment](https://github.com/paritytech/polkadot-sdk/pull/4025#discussion_r1557361473)
- adds `DefaultConfig` for `pallet-xcm-benchmarks` for `system`

Adds sorting to the XCM Assets' `prepend_with`, which could modify the
order of `AssetId` locations.

Relates to: https://github.com/paritytech/polkadot-sdk/pull/4186 (the
same fix for `reanchored`)
Part of: https://github.com/paritytech/polkadot-sdk/pull/2129

# Description
- Link to issue: https://github.com/paritytech/polkadot-sdk/issues/3651

polkadot address: 19nSqFQorfF2HxD3oBzWM3oCh4SaCRKWt1yvmgaPYGCo71J

Preparation for https://github.com/paritytech/polkadot-sdk/pull/3935

Changes:
- Add some `default-features = false` for the case that a crate and that
dependency both support nostd builds.
- Shuffle files around of some benchmarking-only crates. These
conditionally disabled the `cfg_attr` for nostd and pulled in libstd.
Example [here](https://github.com/ggwpez/zepter/pull/95). The actual
logic is moved into a `inner.rs` to preserve nostd capability of the
crate in case the benchmarking feature is disabled.
- Add some `use sp_std::vec` where needed.
- Remove some `optional = true` in cases where it was not optional.
- Removed one superfluous `cfg_attr(not(feature = "std"), no_std..`.

All in all this should be logical no-op.

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

This PR introduces changes enabling the transfer of coretime regions via
XCM.

TL;DR: There are two primary issues that are resolved in this PR:

1. The `mint` and `burn` functions were not implemented for coretime
regions. These operations are essential for moving assets to and from
the XCM holding register.
2. The transfer of non-fungible assets through XCM was previously
disallowed. This was due to incorrectly benchmarking non-fungible asset
transfers via XCM, which led to assigning it a weight of `Weight::Max`,
effectively preventing its execution.

### `mint_into` and `burn` implementation

This PR addresses the issue with cross-chain transferring regions back
to the Coretime chain. Remote reserve transfers are performed by
withdrawing and depositing the asset to and from the holding registry.
This requires the asset to support burning and minting functionality.

This PR adds burning and minting; however, they work a bit differently
than usual so that the associated region record is not lost when
burning. Instead of removing all the data, burning will set the owner of
the region to `None`, and when minting it back, it will set it to an
actual value. So, when cross-chain transferring, withdrawing into the
registry will remove the region from its original owner, and when
depositing it from the registry, it will set its owner to another
account

This was originally implemented in this PR: #3455, however we decided to
move all of it to this single PR
(https://github.com/paritytech/polkadot-sdk/pull/3455#discussion_r1547324892)

### Fixes made in this PR

- Update the `XcmReserveTransferFilter` on coretime chain since it is
meant as a reserve chain for coretime regions.
- Update the XCM benchmark to use `AssetTransactor` instead of assuming
`pallet-balances` for fungible transfers.
- Update the XCM benchmark to properly measure weight consumption for
nonfungible reserve asset transfers. ATM reserve transfers via the
extrinsic do not work since the weight for it is set to `Weight::max()`.

Closes: https://github.com/paritytech/polkadot-sdk/issues/865

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: Dónal Murray <donalm@seadanda.dev>

Introduce types to define 1:1 balance conversion for different relative
asset ids/locations of native asset.

Examples:
native asset on Asset Hub presented as `VersionedLocatableAsset` type in
the context of Relay Chain is
```
{
  `location`: (0, Parachain(1000)),
  `asset_id`: (1, Here),
}
```
and it's balance should be converted 1:1 by implementations of
`ConversionToAssetBalance` trait.

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>

This PR mainly removes `xcm::v3` stuff from `assets-common` to make it
more generic and facilitate the transition to newer XCM versions. Some
of the implementations here used hard-coded `xcm::v3::Location`, but now
it's up to the runtime to configure according to its needs.

Additional/consequent changes:
- `penpal` runtime uses now `xcm::latest::Location` for `pallet_assets`
as `AssetId`, because we don't care about migrations here
- it pretty much simplify xcm-emulator integration tests, where we don't
need now a lots of boilerplate conversions:
      ```
      v3::Location::try_from(...).expect("conversion works")`
      ```
- xcm-emulator tests
- split macro `impl_assets_helpers_for_parachain` to the
`impl_assets_helpers_for_parachain` and
`impl_foreign_assets_helpers_for_parachain` (avoids using hard-coded
`xcm::v3::Location`)

# Description

Add `transfer_assets_using()` for transferring assets from local chain
to destination chain using explicit XCM transfer types such as:
- `TransferType::LocalReserve`: transfer assets to sovereign account of
destination chain and forward a notification XCM to `dest` to mint and
deposit reserve-based assets to `beneficiary`.
- `TransferType::DestinationReserve`: burn local assets and forward a
notification to `dest` chain to withdraw the reserve assets from this
chain's sovereign account and deposit them to `beneficiary`.
- `TransferType::RemoteReserve(reserve)`: burn local assets, forward XCM
to `reserve` chain to move reserves from this chain's SA to `dest`
chain's SA, and forward another XCM to `dest` to mint and deposit
reserve-based assets to `beneficiary`. Typically the remote `reserve` is
Asset Hub.
- `TransferType::Teleport`: burn local assets and forward XCM to `dest`
chain to mint/teleport assets and deposit them to `beneficiary`.

By default, an asset's reserve is its origin chain. But sometimes we may
want to explicitly use another chain as reserve (as long as allowed by
runtime `IsReserve` filter).

This is very helpful for transferring assets with multiple configured
reserves (such as Asset Hub ForeignAssets), when the transfer strictly
depends on the used reserve.

E.g. For transferring Foreign Assets over a bridge, Asset Hub must be
used as the reserve location.

# Example usage scenarios

## Transfer bridged ethereum ERC20-tokenX between ecosystem parachains.

ERC20-tokenX is registered on AssetHub as a ForeignAsset by the
Polkadot<>Ethereum bridge (Snowbridge). Its asset_id is something like
`(parents:2, (GlobalConsensus(Ethereum), Address(tokenX_contract)))`.
Its _original_ reserve is Ethereum (only we can't use Ethereum as a
reserve in local transfers); but, since tokenX is also registered on
AssetHub as a ForeignAsset, we can use AssetHub as a reserve.

With this PR we can transfer tokenX from ParaA to ParaB while using
AssetHub as a reserve.

## Transfer AssetHub ForeignAssets between parachains

AssetA created on ParaA but also registered as foreign asset on Asset
Hub. Can use AssetHub as a reserve.

And all of the above can be done while still controlling transfer type
for `fees` so mixing assets in same transfer is supported.

# Tests

Added integration tests for showcasing:
- transferring local (not bridged) assets from parachain over bridge
using local Asset Hub reserve,
- transferring foreign assets from parachain to Asset Hub,
- transferring foreign assets from Asset Hub to parachain,
- transferring foreign assets from parachain to parachain using local
Asset Hub reserve.

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: command-bot <>

Part of https://github.com/paritytech/polkadot-sdk/issues/226 
Related https://github.com/paritytech/polkadot-sdk/issues/1833

- Deprecate `CurrencyAdapter` and introduce `FungibleAdapter`
- Deprecate `ToStakingPot` and replace usage with `ResolveTo`
- Required creating a new `StakingPotAccountId` struct that implements
`TypedGet` for the staking pot account ID
- Update parachain common utils `DealWithFees`, `ToAuthor` and
`AssetsToBlockAuthor` implementations to use `fungible`
- Update runtime XCM Weight Traders to use `ResolveTo` instead of
`ToStakingPot`
- Update runtime Transaction Payment pallets to use `FungibleAdapter`
instead of `CurrencyAdapter`
- [x] Blocked by https://github.com/paritytech/polkadot-sdk/pull/1296,
needs the `Unbalanced::decrease_balance` fix

The XCM builder pattern lets you build xcms like so:

```rust
let xcm = Xcm::builder()
    .withdraw_asset((Parent, 100u128).into())
    .buy_execution((Parent, 1u128).into())
    .deposit_asset(All.into(), AccountId32 { id: [0u8; 32], network: None }.into())
    .build();
```

All the `.into()` become quite annoying to have to write.
I accepted `impl Into<T>` instead of `T` in the generated methods from
the macro.
Now the previous example can be simplified as follows:

```rust
let xcm = Xcm::builder()
    .withdraw_asset((Parent, 100u128))
    .buy_execution((Parent, 1u128))
    .deposit_asset(All, [0u8; 32])
    .build();
```

---------

Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: command-bot <>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

Added tests for XCM barriers: `AllowSubscriptions`, `WithUniqueTopic` and `TrailingSetTopicAsId` (#3955)

Closes: https://github.com/paritytech/polkadot-sdk/issues/1756

migrations: prevent accidentally using unversioned migrations instead of `VersionedMigration` (#3835)

closes #1324 

#### Problem
Currently, it is possible to accidentally use inner unversioned
migration instead of `VersionedMigration` since both implement
`OnRuntimeUpgrade`.

#### Solution

With this change, we make it clear that value of `Inner` is not intended
to be used directly. It is achieved by bounding `Inner` to new trait
`UncheckedOnRuntimeUpgrade`, which has the same interface (except
`unchecked_` prefix) as `OnRuntimeUpgrade`.

#### `try-runtime` functions

Since developers can implement `try-runtime` for `Inner` value in
`VersionedMigration` and have custom logic for it, I added the same
`try-runtime` functions to `UncheckedOnRuntimeUpgrade`. I looked for a
ways to not duplicate functions, but couldn't find anything that doesn't
significantly change the codebase. So I would appreciate If you have any
suggestions to improve this

cc @liamaharon

 @xlc 

polkadot address: 16FqwPZ8GRC5U5D4Fu7W33nA55ZXzXGWHwmbnE1eT6pxuqcT

---------

Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

Working towards migrating the `parity-bridges-common` repo inside
`polkadot-sdk`. This PR upgrades some dependencies in order to align
them with the versions used in `parity-bridges-common`

Related to
https://github.com/paritytech/parity-bridges-common/issues/2538

Fix "double-weights" for extrinsics, use only the ones benchmarked in
the runtime.

Deprecate extrinsics that don't specify WeightLimit, remove their usage
across the repo.

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: command-bot <>

This will make it possible to use remaining weight on idle for
processing enqueued messages.
More context here https://github.com/paritytech/polkadot-sdk/issues/3709

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

`execute` and `send` try to decode the xcm in the parameters before
reaching the filter line.
The new extrinsics decode only after the filter line.
These should be used instead of the old ones.

## TODO
- [x] Tests
- [x] Generate weights
- [x] Deprecation issue ->
https://github.com/paritytech/polkadot-sdk/issues/3771
- [x] PRDoc
- [x] Handle error in pallet-contracts

This would make writing XCMs in PJS Apps more difficult, but here's the
fix for that: https://github.com/polkadot-js/apps/pull/10350.
Already deployed! https://polkadot.js.org/apps/#/utilities/xcm

Supersedes https://github.com/paritytech/polkadot-sdk/pull/1798/

---------

Co-authored-by: PG Herveou <pgherveou@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

The PR provides API for obtaining:
- the weight required to execute an XCM message,
- a list of acceptable `AssetId`s for message execution payment,
- the cost of the weight in the specified acceptable `AssetId`.

It is meant to address an issue where one has to guess how much fee to
pay for execution. Also, at the moment, a client has to guess which
assets are acceptable for fee execution payment.
See the related issue
https://github.com/paritytech/polkadot-sdk/issues/690.
With this API, a client is supposed to query the list of the supported
asset IDs (in the XCM version format the client understands), weigh the
XCM program the client wants to execute and convert the weight into one
of the acceptable assets. Note that the client is supposed to know what
program will be executed on what chains. However, having a small
companion JS library for the pallet-xcm and xtokens should be enough to
determine what XCM programs will be executed and where (since these
pallets compose a known small set of programs).
```Rust
pub trait XcmPaymentApi<Call>
	where
		Call: Codec,
	{
		/// Returns a list of acceptable payment assets.
		///
		/// # Arguments
		///
		/// * `xcm_version`: Version.
		fn query_acceptable_payment_assets(xcm_version: Version) -> Result<Vec<VersionedAssetId>, Error>;
		/// Returns a weight needed to execute a XCM.
		///
		/// # Arguments
		///
		/// * `message`: `VersionedXcm`.
		fn query_xcm_weight(message: VersionedXcm<Call>) -> Result<Weight, Error>;
		/// Converts a weight into a fee for the specified `AssetId`.
		///
		/// # Arguments
		///
		/// * `weight`: convertible `Weight`.
		/// * `asset`: `VersionedAssetId`.
		fn query_weight_to_asset_fee(weight: Weight, asset: VersionedAssetId) -> Result<u128, Error>;
		/// Get delivery fees for sending a specific `message` to a `destination`.
		/// These always come in a specific asset, defined by the chain.
		///
		/// # Arguments
		/// * `message`: The message that'll be sent, necessary because most delivery fees are based on the
		///   size of the message.
		/// * `destination`: The destination to send the message to. Different destinations may use
		///   different senders that charge different fees.
		fn query_delivery_fees(destination: VersionedLocation, message: VersionedXcm<()>) -> Result<VersionedAssets, Error>;
	}
```
An
[example](https://gist.github.com/PraetorP/4bc323ff85401abe253897ba990ec29d)
of a client side code.

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Daniel Shiposha <mrshiposha@gmail.com>

**Update:** Pushed additional changes based on the review comments.

**This pull request fixes various spelling mistakes in this
repository.**

Most of the changes are contained in the first **3** commits:

- `Fix spelling mistakes in comments and docs`

- `Fix spelling mistakes in test names`

- `Fix spelling mistakes in error messages, panic messages, logs and
tracing`

Other source code spelling mistakes are separated into individual
commits for easier reviewing:

- `Fix the spelling of 'authority'`

- `Fix the spelling of 'REASONABLE_HEADERS_IN_JUSTIFICATION_ANCESTRY'`

- `Fix the spelling of 'prev_enqueud_messages'`

- `Fix the spelling of 'endpoint'`

- `Fix the spelling of 'children'`

- `Fix the spelling of 'PenpalSiblingSovereignAccount'`

- `Fix the spelling of 'PenpalSudoAccount'`

- `Fix the spelling of 'insufficient'`

- `Fix the spelling of 'PalletXcmExtrinsicsBenchmark'`

- `Fix the spelling of 'subtracted'`

- `Fix the spelling of '...

Currently `transfer_assets` from pallet-xcm covers 4 main different
transfer types:
- `localReserve`
- `DestinationReserve`
- `Teleport`
- `RemoteReserve`

For the first three, the local execution and the remote message sending
are separated, and fees are deducted in pallet-xcm itself:
https://github.com/paritytech/polkadot-sdk/blob/3410dfb3

/polkadot/xcm/pallet-xcm/src/lib.rs#L1758.

For the 4th case `RemoteReserve`, pallet-xcm is still relying on the
xcm-executor itself to send the message (through the
`initiateReserveWithdraw` instruction). In this case, if delivery fees
need to be charged, it is not possible to do so because the
`jit_withdraw` mode has not being set.

This PR proposes to still use the `initiateReserveWithdraw` but
prepending a `setFeesMode { jit_withdraw: true }` to make sure delivery
fees can be paid.

A test-case is also added to present the aforementioned case

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

We do not need to make these traits generic over QueryId type, we can
just use the QueryId alias everywhere

Currently the xcm-executor returns an `Unimplemented` error if it
receives any HRMP-related instruction.
What I propose here, which is what we are currently doing in our forked
executor at polimec, is to introduce a trait implemented by the executor
which will handle those instructions.

This way, if parachains want to keep the default behavior, they just use
`()` and it will return unimplemented, but they can also implement their
own logic to establish HRMP channels with other chains in an automated
fashion, without requiring to go through governance.

Our implementation is mentioned in the [polkadot HRMP
docs](https://arc.net/l/quote/hduiivbu), and it was suggested to us to
submit a PR to add these changes to polkadot-sdk.

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: command-bot <>

Step in https://github.com/paritytech/polkadot-sdk/issues/171

This PR removes `as [disambiguation_path]` syntax from `derive_impl`
usage across the polkadot-sdk as introduced in
https://github.com/paritytech/polkadot-sdk/pull/3505

Revert "FRAME: Create `TransactionExtension` as a replacement for `SignedExtension` (#2280)" (#3665)

This PR reverts #2280 which introduced `TransactionExtension` to replace
`SignedExtension`.

As a result of the discussion
[here](https://github.com/paritytech/polkadot-sdk/pull/3623#issuecomment-1986789700),
the changes will be reverted for now with plans to reintroduce the
concept in the future.

---------

Signed-off-by: georgepisaltu <george.pisaltu@parity.io>

Closes #2160

First part of [Extrinsic
Horizon](https://github.com/paritytech/polkadot-sdk/issues/2415)

Introduces a new trait `TransactionExtension` to replace
`SignedExtension`. Introduce the idea of transactions which obey the
runtime's extensions and have according Extension data (né Extra data)
yet do not have hard-coded signatures.

Deprecate the terminology of "Unsigned" when used for
transactions/extrinsics owing to there now being "proper" unsigned
transactions which obey the extension framework and "old-style" unsigned
which do not. Instead we have __*General*__ for the former and
__*Bare*__ for the latter. (Ultimately, the latter will be phased out as
a type of transaction, and Bare will only be used for Inherents.)

Types of extrinsic are now therefore:
- Bare (no hardcoded signature, no Extra data; used to be known as
"Unsigned")
- Bare transactions (deprecated): Gossiped, validated with
`ValidateUnsigned` (deprecated) and the `_bare_compat` bits of
`TransactionExtension` (deprecated).
  - Inherents: Not gossiped, validated with `ProvideInherent`.
- Extended (Extra data): Gossiped, validated via `TransactionExtension`.
  - Signed transactions (with a hardcoded signature).
  - General transactions (without a hardcoded signature).

`TransactionExtension` differs from `SignedExtension` because:
- A signature on the underlying transaction may validly not be present.
- It may alter the origin during validation.
- `pre_dispatch` is renamed to `prepare` and need not contain the checks
present in `validate`.
- `validate` and `prepare` is passed an `Origin` rather than a
`AccountId`.
- `validate` may pass arbitrary information into `prepare` via a new
user-specifiable type `Val`.
- `AdditionalSigned`/`additional_signed` is renamed to
`Implicit`/`implicit`. It is encoded *for the entire transaction* and
passed in to each extension as a new argument to `validate`. This
facilitates the ability of extensions to acts as underlying crypto.

There is a new `DispatchTransaction` trait which contains only default
function impls and is impl'ed for any `TransactionExtension` impler. It
provides several utility functions which reduce some of the tedium from
using `TransactionExtension` (indeed, none of its regular functions
should now need to be called directly).

Three transaction version discriminator ("versions") are now
permissible:
- 0b000000100: Bare (used to be called "Unsigned"): contains Signature
or Extra (extension data). After bare transactions are no longer
supported, this will strictly identify an Inherents only.
- 0b100000100: Old-school "Signed" Transaction: contains Signature and
Extra (extension data).
- 0b010000100: New-school "General" Transaction: contains Extra
(extension data), but no Signature.

For the New-school General Transaction, it becomes trivial for authors
to publish extensions to the mechanism for authorizing an Origin, e.g.
through new kinds of key-signing schemes, ZK proofs, pallet state,
mutations over pre-authenticated origins or any combination of the
above.

## Code Migration

### NOW: Getting it to build

Wrap your `SignedExtension`s in `AsTransactionExtension`. This should be
accompanied by renaming your aggregate type in line with the new
terminology. E.g. Before:

```rust
/// The SignedExtension to the basic transaction logic.
pub type SignedExtra = (
	/* snip */
	MySpecialSignedExtension,
);
/// Unchecked extrinsic type as expected by this runtime.
pub type UncheckedExtrinsic =
	generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, SignedExtra>;
```

After:

```rust
/// The extension to the basic transaction logic.
pub type TxExtension = (
	/* snip */
	AsTransactionExtension<MySpecialSignedExtension>,
);
/// Unchecked extrinsic type as expected by this runtime.
pub type UncheckedExtrinsic =
	generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, TxExtension>;
```

You'll also need to alter any transaction building logic to add a
`.into()` to make the conversion happen. E.g. Before:

```rust
fn construct_extrinsic(
		/* snip */
) -> UncheckedExtrinsic {
	let extra: SignedExtra = (
		/* snip */
		MySpecialSignedExtension::new(/* snip */),
	);
	let payload = SignedPayload::new(call.clone(), extra.clone()).unwrap();
	let signature = payload.using_encoded(|e| sender.sign(e));
	UncheckedExtrinsic::new_signed(
		/* snip */
		Signature::Sr25519(signature),
		extra,
	)
}
```

After:

```rust
fn construct_extrinsic(
		/* snip */
) -> UncheckedExtrinsic {
	let tx_ext: TxExtension = (
		/* snip */
		MySpecialSignedExtension::new(/* snip */).into(),
	);
	let payload = SignedPayload::new(call.clone(), tx_ext.clone()).unwrap();
	let signature = payload.using_encoded(|e| sender.sign(e));
	UncheckedExtrinsic::new_signed(
		/* snip */
		Signature::Sr25519(signature),
		tx_ext,
	)
}
```

### SOON: Migrating to `TransactionExtension`

Most `SignedExtension`s can be trivially converted to become a
`TransactionExtension`. There are a few things to know.

- Instead of a single trait like `SignedExtension`, you should now
implement two traits individually: `TransactionExtensionBase` and
`TransactionExtension`.
- Weights are now a thing and must be provided via the new function `fn
weight`.

#### `TransactionExtensionBase`

This trait takes care of anything which is not dependent on types
specific to your runtime, most notably `Call`.

- `AdditionalSigned`/`additional_signed` is renamed to
`Implicit`/`implicit`.
- Weight must be returned by implementing the `weight` function. If your
extension is associated with a pallet, you'll probably want to do this
via the pallet's existing benchmarking infrastructure.

#### `TransactionExtension`

Generally:
- `pre_dispatch` is now `prepare` and you *should not reexecute the
`validate` functionality in there*!
- You don't get an account ID any more; you get an origin instead. If
you need to presume an account ID, then you can use the trait function
`AsSystemOriginSigner::as_system_origin_signer`.
- You get an additional ticket, similar to `Pre`, called `Val`. This
defines data which is passed from `validate` into `prepare`. This is
important since you should not be duplicating logic from `validate` to
`prepare`, you need a way of passing your working from the former into
the latter. This is it.
- This trait takes two type parameters: `Call` and `Context`. `Call` is
the runtime call type which used to be an associated type; you can just
move it to become a type parameter for your trait impl. `Context` is not
currently used and you can safely implement over it as an unbounded
type.
- There's no `AccountId` associated type any more. Just remove it.

Regarding `validate`:
- You get three new parameters in `validate`; all can be ignored when
migrating from `SignedExtension`.
- `validate` returns a tuple on success; the second item in the tuple is
the new ticket type `Self::Val` which gets passed in to `prepare`. If
you use any information extracted during `validate` (off-chain and
on-chain, non-mutating) in `prepare` (on-chain, mutating) then you can
pass it through with this. For the tuple's last item, just return the
`origin` argument.

Regarding `prepare`:
- This is renamed from `pre_dispatch`, but there is one change:
- FUNCTIONALITY TO VALIDATE THE TRANSACTION NEED NOT BE DUPLICATED FROM
`validate`!!
- (This is different to `SignedExtension` which was required to run the
same checks in `pre_dispatch` as in `validate`.)

Regarding `post_dispatch`:
- Since there are no unsigned transactions handled by
`TransactionExtension`, `Pre` is always defined, so the first parameter
is `Self::Pre` rather than `Option<Self::Pre>`.

If you make use of `SignedExtension::validate_unsigned` or
`SignedExtension::pre_dispatch_unsigned`, then:
- Just use the regular versions of these functions instead.
- Have your logic execute in the case that the `origin` is `None`.
- Ensure your transaction creation logic creates a General Transaction
rather than a Bare Transaction; this means having to include all
`TransactionExtension`s' data.
- `ValidateUnsigned` can still be used (for now) if you need to be able
to construct transactions which contain none of the extension data,
however these will be phased out in stage 2 of the Transactions Horizon,
so you should consider moving to an extension-centric design.

## TODO

- [x] Introduce `CheckSignature` impl of `TransactionExtension` to
ensure it's possible to have crypto be done wholly in a
`TransactionExtension`.
- [x] Deprecate `SignedExtension` and move all uses in codebase to
`TransactionExtension`.
  - [x] `ChargeTransactionPayment`
  - [x] `DummyExtension`
  - [x] `ChargeAssetTxPayment` (asset-tx-payment)
  - [x] `ChargeAssetTxPayment` (asset-conversion-tx-payment)
  - [x] `CheckWeight`
  - [x] `CheckTxVersion`
  - [x] `CheckSpecVersion`
  - [x] `CheckNonce`
  - [x] `CheckNonZeroSender`
  - [x] `CheckMortality`
  - [x] `CheckGenesis`
  - [x] `CheckOnlySudoAccount`
  - [x] `WatchDummy`
  - [x] `PrevalidateAttests`
  - [x] `GenericSignedExtension`
  - [x] `SignedExtension` (chain-polkadot-bulletin)
  - [x] `RefundSignedExtensionAdapter`
- [x] Implement `fn weight` across the board.
- [ ] Go through all pre-existing extensions which assume an account
signer and explicitly handle the possibility of another kind of origin.
- [x] `CheckNonce` should probably succeed in the case of a non-account
origin.
- [x] `CheckNonZeroSender` should succeed in the case of a non-account
origin.
- [x] `ChargeTransactionPayment` and family should fail in the case of a
non-account origin.
  - [ ] 
- [x] Fix any broken tests.

---------

Signed-off-by: georgepisaltu <george.pisaltu@parity.io>
Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Signed-off-by: dependabot[bot] <support@github.com>
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Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>
Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>
Co-authored-by: Nikhil Gupta <17176722+gupnik@users.noreply.github.com>
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If an XCM execution fails or ends with leftover assets, these will be
trapped.
In order to claim them, a custom XCM has to be executed, with the
`ClaimAsset` instruction.
However, arbitrary XCM execution is not allowed everywhere yet and XCM
itself is still not easy enough to use for users out there with trapped
assets.
This new extrinsic in `pallet-xcm` will allow these users to easily
claim their assets, without concerning themselves with writing arbitrary
XCMs.

Part of fixing https://github.com/paritytech/polkadot-sdk/issues/3495

---------

Co-authored-by: command-bot <>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

## Problem
During the bumping of the `polkadot-fellows` repository to
`polkadot-sdk@1.6.0`, I encountered a situation where the benchmarks
`teleport_assets` and `reserve_transfer_assets` in AssetHubKusama
started to fail. This issue arose due to a decreased ED balance for
AssetHubs introduced
[here](https://github.com/polkadot-fellows/runtimes/pull/158/files#diff-80668ff8e793b64f36a9a3ec512df5cbca4ad448c157a5d81abda1b15f35f1daR213),
and also because of a [missing CI
pipeline](https://github.com/polkadot-fellows/runtimes/issues/197) to
check the benchmarks, which went unnoticed.

These benchmarks expect the `caller` to have enough:
1. balance to transfer (BTT)
2. balance for paying delivery (BFPD).
 
So the initial balance was calculated as `ED * 100`, which seems
reasonable:
```
const ED_MULTIPLIER: u32 = 100;
let balance = existential_deposit.saturating_mul(ED_MULTIPLIER.into());`
```
The problem arises when the price for delivery is 100 times higher than
the existential deposit. In other words, when `ED * 100` does not cover
`BTT` + `BFPD`.

I check AHR/AHW/AHK/AHP and this problem has only AssetHubKusama
```
ED: 3333333
calculated price to parent delivery:  1031666634  (from xcm logs from the benchmark)
---

3333333 * 100 - BTT(3333333) - BFPD(1031666634) = −701666667
```
which results in the error;
```
2024-02-23 09:19:42 Unable to charge fee with error Module(ModuleError { index: 31, error: [17, 0, 0, 0], message: Some("FeesNotMet") })
Error: Input("Benchmark pallet_xcm::reserve_transfer_assets failed: FeesNotMet")
     
```

## Solution

The benchmarks `teleport_assets` and `reserve_transfer_assets` were
fixed by removing `ED * 100` and replacing it with `DeliveryHelper`
logic, which calculates the (almost real) price for delivery and sets it
along with the existential deposit as the initial balance for the
account used in the benchmark.


## TODO

- [ ] patch for 1.6 -
https://github.com/paritytech/polkadot-sdk/pull/3466
- [ ] patch for 1.7 -
https://github.com/paritytech/polkadot-sdk/pull/3465
- [ ] patch for 1.8 - TODO: PR

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

The `fee` should be calculated with the reanchored asset, otherwise it
could lead to a failure where the set aside fee ends up not being
enough.

@acatangiu



---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>