From 5aa46775c0600fe722510abff30fc3eff313acbc Mon Sep 17 00:00:00 2001
From: Adrian Catangiu <adrian@parity.io>
Date: Wed, 31 May 2023 17:15:05 +0300
Subject: [PATCH] pallet-beefy-mmr: fix when using custom hashing (#14273)

`Hash` is no longer part of `pallet_mmr::Config`, but this code
would still build because it assumes we're referring to underlying
`<pallet_mmr::Config as frame_system::Config>::Hash` which is not
what we want when using different hashing between `frame_system`
and `pallet_mmr`.

Disambiguate by using correct `pallet_mmr::Config::Hashing` type.

Signed-off-by: acatangiu <adrian@parity.io>
---
 frame/beefy-mmr/src/lib.rs            | 2 +-
 primitives/consensus/beefy/src/lib.rs | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/frame/beefy-mmr/src/lib.rs b/frame/beefy-mmr/src/lib.rs
index 686f3c56f82b1..ba416922e2563 100644
--- a/frame/beefy-mmr/src/lib.rs
+++ b/frame/beefy-mmr/src/lib.rs
@@ -56,7 +56,7 @@ pub struct DepositBeefyDigest<T>(sp_std::marker::PhantomData<T>);
 
 impl<T> pallet_mmr::primitives::OnNewRoot<sp_consensus_beefy::MmrRootHash> for DepositBeefyDigest<T>
 where
-	T: pallet_mmr::Config<Hash = sp_consensus_beefy::MmrRootHash>,
+	T: pallet_mmr::Config<Hashing = sp_consensus_beefy::MmrHashing>,
 	T: pallet_beefy::Config,
 {
 	fn on_new_root(root: &sp_consensus_beefy::MmrRootHash) {
diff --git a/primitives/consensus/beefy/src/lib.rs b/primitives/consensus/beefy/src/lib.rs
index 268e1925b4449..6132c01187f01 100644
--- a/primitives/consensus/beefy/src/lib.rs
+++ b/primitives/consensus/beefy/src/lib.rs
@@ -47,7 +47,7 @@ use codec::{Codec, Decode, Encode};
 use scale_info::TypeInfo;
 use sp_application_crypto::RuntimeAppPublic;
 use sp_core::H256;
-use sp_runtime::traits::{Hash, NumberFor};
+use sp_runtime::traits::{Hash, Keccak256, NumberFor};
 use sp_std::prelude::*;
 
 /// Key type for BEEFY module.
@@ -156,6 +156,8 @@ impl<AuthorityId> ValidatorSet<AuthorityId> {
 /// The index of an authority.
 pub type AuthorityIndex = u32;
 
+/// The Hashing used within MMR.
+pub type MmrHashing = Keccak256;
 /// The type used to represent an MMR root hash.
 pub type MmrRootHash = H256;