Make RelayedFrom typesafe (#3617)

* Corrent type

* Fix build

* Fixes

* Fixes

* Formatting

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

@@ -106,6 +106,8 @@ pub mod pallet {
 		CannotReanchor,
 		/// Too many assets have been attempted for transfer.
 		TooManyAssets,
+		/// Origin is invalid for sending.
+		InvalidOrigin,
 	}
 
 	#[pallet::hooks]
@@ -120,12 +122,12 @@ pub mod pallet {
 			message: Box<Xcm<()>>,
 		) -> DispatchResult {
 			let origin_location = T::SendXcmOrigin::ensure_origin(origin)?;
-			Self::send_xcm(origin_location.clone(), *dest.clone(), *message.clone()).map_err(
-				|e| match e {
-					XcmError::CannotReachDestination(..) => Error::<T>::Unreachable,
-					_ => Error::<T>::SendFailure,
-				},
-			)?;
+			let interior =
+				origin_location.clone().try_into().map_err(|_| Error::<T>::InvalidOrigin)?;
+			Self::send_xcm(interior, *dest.clone(), *message.clone()).map_err(|e| match e {
+				XcmError::CannotReachDestination(..) => Error::<T>::Unreachable,
+				_ => Error::<T>::SendFailure,
+			})?;
 			Self::deposit_event(Event::Sent(origin_location, *dest, *message));
 			Ok(())
 		}
@@ -302,11 +304,11 @@ pub mod pallet {
 		/// Relay an XCM `message` from a given `interior` location in this context to a given `dest`
 		/// location. A null `dest` is not handled.
 		pub fn send_xcm(
-			interior: MultiLocation,
+			interior: Junctions,
 			dest: MultiLocation,
 			message: Xcm<()>,
 		) -> Result<(), XcmError> {
-			let message = if interior.is_here() {
+			let message = if let Junctions::Here = interior {
 				message
 			} else {
 				Xcm::<()>::RelayedFrom { who: interior, message: Box::new(message) }

polkadot/xcm/pallet-xcm/src/tests.rs

@@ -17,10 +17,8 @@
 use crate::mock::*;
 use frame_support::{assert_noop, assert_ok, traits::Currency};
 use polkadot_parachain::primitives::{AccountIdConversion, Id as ParaId};
-use xcm::{
-	opaque::v1::prelude::*,
-	v1::{Junction, Xcm},
-};
+use std::convert::TryInto;
+use xcm::v1::prelude::*;
 
 const ALICE: AccountId = AccountId::new([0u8; 32]);
 const BOB: AccountId = AccountId::new([1u8; 32]);
@@ -55,7 +53,10 @@ fn send_works() {
 			sent_xcm(),
 			vec![(
 				Here.into(),
-				RelayedFrom { who: sender.clone(), message: Box::new(message.clone()) }
+				RelayedFrom {
+					who: sender.clone().try_into().unwrap(),
+					message: Box::new(message.clone()),
+				}
 			)]
 		);
 		assert_eq!(