Reduce usage of Blake2Hasher (#5132)

This reduces the usage of `Blake2Hasher` in the code base and replaces
it with `BlakeTwo256`. The most important change is the removal of the
custom extern function for `Blake2Hasher`. The runtime `Hash` trait is
now also simplified and directly requires that the implementing type
implements `Hashable`.

substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs

@@ -237,7 +237,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 		pub struct RuntimeApiImpl<Block: #crate_::BlockT, C: #crate_::CallApiAt<Block> + 'static>
 			where
 				// Rust bug: https://github.com/rust-lang/rust/issues/24159
-				C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+				C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{
 			call: &'static C,
 			commit_on_success: std::cell::RefCell<bool>,
@@ -257,7 +257,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 			for RuntimeApiImpl<Block, C>
 				where
 					// Rust bug: https://github.com/rust-lang/rust/issues/24159
-					C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+					C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{}
 
 		#[cfg(any(feature = "std", test))]
@@ -265,7 +265,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 			for RuntimeApiImpl<Block, C>
 				where
 					// Rust bug: https://github.com/rust-lang/rust/issues/24159
-					C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+					C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{}
 
 		#[cfg(any(feature = "std", test))]
@@ -273,7 +273,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 			for RuntimeApiImpl<Block, C>
 				where
 					// Rust bug: https://github.com/rust-lang/rust/issues/24159
-					C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+					C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{
 			type Error = C::Error;
 		}
@@ -283,7 +283,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 			RuntimeApiImpl<Block, C>
 				where
 					// Rust bug: https://github.com/rust-lang/rust/issues/24159
-					C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+					C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{
 			type StateBackend = C::StateBackend;
 
@@ -327,7 +327,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 				&self,
 				backend: &Self::StateBackend,
 				changes_trie_state: Option<&#crate_::ChangesTrieState<
-					#crate_::HasherFor<Block>,
+					#crate_::HashFor<Block>,
 					#crate_::NumberFor<Block>,
 				>>,
 				parent_hash: Block::Hash,
@@ -351,7 +351,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 				where
 					C: #crate_::CallApiAt<Block> + 'static,
 					// Rust bug: https://github.com/rust-lang/rust/issues/24159
-					C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+					C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{
 			type RuntimeApi = RuntimeApiImpl<Block, C>;
 
@@ -373,7 +373,7 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 		impl<Block: #crate_::BlockT, C: #crate_::CallApiAt<Block>> RuntimeApiImpl<Block, C>
 			where
 				// Rust bug: https://github.com/rust-lang/rust/issues/24159
-				C::StateBackend: #crate_::StateBackend<#crate_::HasherFor<Block>>,
+				C::StateBackend: #crate_::StateBackend<#crate_::HashFor<Block>>,
 		{
 			fn call_api_at<
 				R: #crate_::Encode + #crate_::Decode + PartialEq,
@@ -603,7 +603,7 @@ impl<'a> Fold for ApiRuntimeImplToApiRuntimeApiImpl<'a> {
 		where_clause.predicates.push(
 			parse_quote! {
 				RuntimeApiImplCall::StateBackend:
-					#crate_::StateBackend<#crate_::HasherFor<__SR_API_BLOCK__>>
+					#crate_::StateBackend<#crate_::HashFor<__SR_API_BLOCK__>>
 			}
 		);
 

substrate/primitives/api/src/lib.rs

@@ -50,7 +50,7 @@ pub use sp_core::to_substrate_wasm_fn_return_value;
 #[doc(hidden)]
 pub use sp_runtime::{
 	traits::{
-		Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, HasherFor, NumberFor,
+		Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, HashFor, NumberFor,
 		Header as HeaderT, Hash as HashT,
 	},
 	generic::BlockId, transaction_validity::TransactionValidity,
@@ -228,22 +228,20 @@ pub use sp_api_proc_macro::impl_runtime_apis;
 
 /// A type that records all accessed trie nodes and generates a proof out of it.
 #[cfg(feature = "std")]
-pub type ProofRecorder<B> = sp_state_machine::ProofRecorder<
-	<<<B as BlockT>::Header as HeaderT>::Hashing as HashT>::Hasher
->;
+pub type ProofRecorder<B> = sp_state_machine::ProofRecorder<HashFor<B>>;
 
 /// A type that is used as cache for the storage transactions.
 #[cfg(feature = "std")]
 pub type StorageTransactionCache<Block, Backend> =
 	sp_state_machine::StorageTransactionCache<
-		<Backend as StateBackend<HasherFor<Block>>>::Transaction, HasherFor<Block>, NumberFor<Block>
+		<Backend as StateBackend<HashFor<Block>>>::Transaction, HashFor<Block>, NumberFor<Block>
 	>;
 
 #[cfg(feature = "std")]
 pub type StorageChanges<SBackend, Block> =
 	sp_state_machine::StorageChanges<
-		<SBackend as StateBackend<HasherFor<Block>>>::Transaction,
-		HasherFor<Block>,
+		<SBackend as StateBackend<HashFor<Block>>>::Transaction,
+		HashFor<Block>,
 		NumberFor<Block>
 	>;
 
@@ -255,7 +253,7 @@ pub type StateBackendFor<P, Block> =
 /// Extract the state backend transaction type for a type that implements `ProvideRuntimeApi`.
 #[cfg(feature = "std")]
 pub type TransactionFor<P, Block> =
-	<StateBackendFor<P, Block> as StateBackend<HasherFor<Block>>>::Transaction;
+	<StateBackendFor<P, Block> as StateBackend<HashFor<Block>>>::Transaction;
 
 /// Something that can be constructed to a runtime api.
 #[cfg(feature = "std")]
@@ -279,7 +277,7 @@ pub trait ApiErrorExt {
 #[cfg(feature = "std")]
 pub trait ApiExt<Block: BlockT>: ApiErrorExt {
 	/// The state backend that is used to store the block states.
-	type StateBackend: StateBackend<HasherFor<Block>>;
+	type StateBackend: StateBackend<HashFor<Block>>;
 
 	/// The given closure will be called with api instance. Inside the closure any api call is
 	/// allowed. After doing the api call, the closure is allowed to map the `Result` to a
@@ -328,7 +326,7 @@ pub trait ApiExt<Block: BlockT>: ApiErrorExt {
 	fn into_storage_changes(
 		&self,
 		backend: &Self::StateBackend,
-		changes_trie_state: Option<&ChangesTrieState<HasherFor<Block>, NumberFor<Block>>>,
+		changes_trie_state: Option<&ChangesTrieState<HashFor<Block>, NumberFor<Block>>>,
 		parent_hash: Block::Hash,
 	) -> Result<StorageChanges<Self::StateBackend, Block>, String> where Self: Sized;
 }
@@ -355,7 +353,7 @@ pub enum InitializeBlock<'a, Block: BlockT> {
 
 /// Parameters for [`CallApiAt::call_api_at`].
 #[cfg(feature = "std")]
-pub struct CallApiAtParams<'a, Block: BlockT, C, NC, Backend: StateBackend<HasherFor<Block>>> {
+pub struct CallApiAtParams<'a, Block: BlockT, C, NC, Backend: StateBackend<HashFor<Block>>> {
 	/// A reference to something that implements the [`Core`] api.
 	pub core_api: &'a C,
 	/// The block id that determines the state that should be setup when calling the function.
@@ -389,7 +387,7 @@ pub trait CallApiAt<Block: BlockT> {
 	type Error: std::fmt::Debug + From<String>;
 
 	/// The state backend that is used to store the block states.
-	type StateBackend: StateBackend<HasherFor<Block>>;
+	type StateBackend: StateBackend<HashFor<Block>>;
 
 	/// Calls the given api function with the given encoded arguments at the given block and returns
 	/// the encoded result.

substrate/primitives/api/test/tests/runtime_calls.rs

@@ -18,9 +18,9 @@ use sp_api::ProvideRuntimeApi;
 use substrate_test_runtime_client::{
 	prelude::*,
 	DefaultTestClientBuilderExt, TestClientBuilder,
-	runtime::{TestAPI, DecodeFails, Transfer, Header},
+	runtime::{TestAPI, DecodeFails, Transfer, Block},
 };
-use sp_runtime::{generic::BlockId, traits::{Header as HeaderT, Hash as HashT}};
+use sp_runtime::{generic::BlockId, traits::{Header as HeaderT, HashFor}};
 use sp_state_machine::{
 	ExecutionStrategy, create_proof_check_backend,
 	execution_proof_check_on_trie_backend,
@@ -184,7 +184,7 @@ fn record_proof_works() {
 	builder.push(transaction.clone()).unwrap();
 	let (block, _, proof) = builder.build().expect("Bake block").into_inner();
 
-	let backend = create_proof_check_backend::<<<Header as HeaderT>::Hashing as HashT>::Hasher>(
+	let backend = create_proof_check_backend::<HashFor<Block>>(
 		storage_root,
 		proof.expect("Proof was generated"),
 	).expect("Creates proof backend.");