rococo-runtime: use mmr-specific Hash (#7318)

pallet-mmr can be configured with a different hashing scheme
than frame-system pallet. Make sure to use this custom type
for MmrApi.

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

runtime/rococo/src/lib.rs

@@ -70,7 +70,6 @@ use pallet_im_online::sr25519::AuthorityId as ImOnlineId;
 use pallet_session::historical as session_historical;
 use pallet_transaction_payment::{CurrencyAdapter, FeeDetails, RuntimeDispatchInfo};
 use sp_core::{ConstU128, OpaqueMetadata, H256};
-use sp_mmr_primitives as mmr;
 use sp_runtime::{
 	create_runtime_str, generic, impl_opaque_keys,
 	traits::{
@@ -1281,6 +1280,16 @@ impl pallet_beefy::Config for Runtime {
 		pallet_beefy::EquivocationReportSystem<Self, Offences, Historical, ReportLongevity>;
 }
 
+/// MMR helper types.
+mod mmr {
+	use super::Runtime;
+	pub use pallet_mmr::primitives::*;
+
+	pub type Leaf = <<Runtime as pallet_mmr::Config>::LeafData as LeafDataProvider>::LeafData;
+	pub type Hashing = <Runtime as pallet_mmr::Config>::Hashing;
+	pub type Hash = <Hashing as sp_runtime::traits::Hash>::Output;
+}
+
 impl pallet_mmr::Config for Runtime {
 	const INDEXING_PREFIX: &'static [u8] = mmr::INDEXING_PREFIX;
 	type Hashing = Keccak256;
@@ -1314,7 +1323,7 @@ impl BeefyDataProvider<H256> for ParasProvider {
 			.filter_map(|id| Paras::para_head(&id).map(|head| (id.into(), head.0)))
 			.collect();
 		para_heads.sort();
-		binary_merkle_tree::merkle_root::<<Runtime as pallet_mmr::Config>::Hashing, _>(
+		binary_merkle_tree::merkle_root::<mmr::Hashing, _>(
 			para_heads.into_iter().map(|pair| pair.encode()),
 		)
 		.into()
@@ -1731,8 +1740,6 @@ mod benches {
 	);
 }
 
-pub type MmrHashing = <Runtime as pallet_mmr::Config>::Hashing;
-
 #[cfg(not(feature = "disable-runtime-api"))]
 sp_api::impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {
@@ -1972,8 +1979,8 @@ sp_api::impl_runtime_apis! {
 	}
 
 	#[api_version(2)]
-	impl mmr::MmrApi<Block, Hash, BlockNumber> for Runtime {
-		fn mmr_root() -> Result<Hash, mmr::Error> {
+	impl mmr::MmrApi<Block, mmr::Hash, BlockNumber> for Runtime {
+		fn mmr_root() -> Result<mmr::Hash, mmr::Error> {
 			Ok(Mmr::mmr_root())
 		}
 
@@ -1984,7 +1991,7 @@ sp_api::impl_runtime_apis! {
 		fn generate_proof(
 			block_numbers: Vec<BlockNumber>,
 			best_known_block_number: Option<BlockNumber>,
-		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<Hash>), mmr::Error> {
+		) -> Result<(Vec<mmr::EncodableOpaqueLeaf>, mmr::Proof<mmr::Hash>), mmr::Error> {
 			Mmr::generate_proof(block_numbers, best_known_block_number).map(
 				|(leaves, proof)| {
 					(
@@ -1998,24 +2005,23 @@ sp_api::impl_runtime_apis! {
 			)
 		}
 
-		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::Proof<Hash>)
+		fn verify_proof(leaves: Vec<mmr::EncodableOpaqueLeaf>, proof: mmr::Proof<mmr::Hash>)
 			-> Result<(), mmr::Error>
 		{
-			pub type MmrLeaf = <<Runtime as pallet_mmr::Config>::LeafData as mmr::LeafDataProvider>::LeafData;
 			let leaves = leaves.into_iter().map(|leaf|
 				leaf.into_opaque_leaf()
 				.try_decode()
-				.ok_or(mmr::Error::Verify)).collect::<Result<Vec<MmrLeaf>, mmr::Error>>()?;
+				.ok_or(mmr::Error::Verify)).collect::<Result<Vec<mmr::Leaf>, mmr::Error>>()?;
 			Mmr::verify_leaves(leaves, proof)
 		}
 
 		fn verify_proof_stateless(
-			root: Hash,
+			root: mmr::Hash,
 			leaves: Vec<mmr::EncodableOpaqueLeaf>,
-			proof: mmr::Proof<Hash>
+			proof: mmr::Proof<mmr::Hash>
 		) -> Result<(), mmr::Error> {
 			let nodes = leaves.into_iter().map(|leaf|mmr::DataOrHash::Data(leaf.into_opaque_leaf())).collect();
-			pallet_mmr::verify_leaves_proof::<MmrHashing, _>(root, nodes, proof)
+			pallet_mmr::verify_leaves_proof::<mmr::Hashing, _>(root, nodes, proof)
 		}
 	}