The storage runtime interface should not enforce a hash type (#4231)

* The storage runtime interface should not enforce a hash type

Currently the runtime interface enforces `H256` as hash type, but in the
future people could use whatever they want as hash type. The hash type
always needs to match between the runtime and the node, but that is
already required.

* Update primitives/externalities/src/lib.rs

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

substrate/primitives/state-machine/src/changes_trie/build.rs

@@ -18,7 +18,7 @@
 
 use std::collections::{BTreeMap, BTreeSet};
 use std::collections::btree_map::Entry;
-use codec::Decode;
+use codec::{Decode, Encode};
 use hash_db::Hasher;
 use num_traits::One;
 use crate::backend::Backend;
@@ -47,6 +47,7 @@ pub(crate) fn prepare_input<'a, B, H, Number>(
 	where
 		B: Backend<H>,
 		H: Hasher + 'a,
+		H::Out: Encode,
 		Number: BlockNumber,
 {
 	let number = parent.number.clone() + One::one();
@@ -200,7 +201,7 @@ fn prepare_digest_input<'a, H, Number>(
 	), String>
 	where
 		H: Hasher,
-		H::Out: 'a,
+		H::Out: 'a + Encode,
 		Number: BlockNumber,
 {
 	let build_skewed_digest = config.end.as_ref() == Some(&block);

substrate/primitives/state-machine/src/changes_trie/changes_iterator.rs

@@ -19,7 +19,7 @@
 
 use std::cell::RefCell;
 use std::collections::VecDeque;
-use codec::{Decode, Encode};
+use codec::{Decode, Encode, Codec};
 use hash_db::Hasher;
 use num_traits::Zero;
 use trie::Recorder;
@@ -81,7 +81,7 @@ pub fn key_changes_proof<'a, H: Hasher, Number: BlockNumber>(
 	max: Number,
 	storage_key: Option<&[u8]>,
 	key: &[u8],
-) -> Result<Vec<Vec<u8>>, String> {
+) -> Result<Vec<Vec<u8>>, String> where H::Out: Codec {
 	// we can't query any roots before root
 	let max = ::std::cmp::min(max.clone(), end.number.clone());
 
@@ -129,7 +129,7 @@ pub fn key_changes_proof_check<'a, H: Hasher, Number: BlockNumber>(
 	max: Number,
 	storage_key: Option<&[u8]>,
 	key: &[u8]
-) -> Result<Vec<(Number, u32)>, String> {
+) -> Result<Vec<(Number, u32)>, String> where H::Out: Encode {
 	key_changes_proof_check_with_db(
 		config,
 		roots_storage,
@@ -152,7 +152,7 @@ pub fn key_changes_proof_check_with_db<'a, H: Hasher, Number: BlockNumber>(
 	max: Number,
 	storage_key: Option<&[u8]>,
 	key: &[u8]
-) -> Result<Vec<(Number, u32)>, String> {
+) -> Result<Vec<(Number, u32)>, String> where H::Out: Encode {
 	// we can't query any roots before root
 	let max = ::std::cmp::min(max.clone(), end.number.clone());
 
@@ -316,8 +316,8 @@ pub struct DrilldownIterator<'a, H, Number>
 	essence: DrilldownIteratorEssence<'a, H, Number>,
 }
 
-impl<'a, H: Hasher, Number: BlockNumber> Iterator
-	for DrilldownIterator<'a, H, Number>
+impl<'a, H: Hasher, Number: BlockNumber> Iterator for DrilldownIterator<'a, H, Number>
+	where H::Out: Encode
 {
 	type Item = Result<(Number, u32), String>;
 
@@ -358,7 +358,7 @@ impl<'a, H, Number> Iterator for ProvingDrilldownIterator<'a, H, Number>
 	where
 		Number: BlockNumber,
 		H: Hasher,
-		H::Out: 'a,
+		H::Out: 'a + Codec,
 {
 	type Item = Result<(Number, u32), String>;
 

substrate/primitives/state-machine/src/changes_trie/mod.rs

@@ -181,7 +181,7 @@ pub fn build_changes_trie<'a, B: Backend<H>, S: Storage<H, Number>, H: Hasher, N
 	parent_hash: H::Out,
 ) -> Result<Option<(MemoryDB<H>, H::Out, CacheAction<H::Out, Number>)>, ()>
 	where
-		H::Out: Ord + 'static,
+		H::Out: Ord + 'static + Encode,
 {
 	let (storage, config) = match (storage, changes.changes_trie_config.as_ref()) {
 		(Some(storage), Some(config)) => (storage, config),

substrate/primitives/state-machine/src/changes_trie/prune.rs

@@ -25,7 +25,7 @@ use crate::trie_backend_essence::TrieBackendEssence;
 use crate::changes_trie::{AnchorBlockId, Configuration, Storage, BlockNumber};
 use crate::changes_trie::storage::TrieBackendAdapter;
 use crate::changes_trie::input::{ChildIndex, InputKey};
-use codec::Decode;
+use codec::{Decode, Codec};
 
 /// Get number of oldest block for which changes trie is not pruned
 /// given changes trie configuration, pruning parameter and number of
@@ -55,7 +55,7 @@ pub fn prune<S: Storage<H, Number>, H: Hasher, Number: BlockNumber, F: FnMut(H::
 	min_blocks_to_keep: Number,
 	current_block: &AnchorBlockId<H::Out, Number>,
 	mut remove_trie_node: F,
-) {
+) where H::Out: Codec {
 
 	// select range for pruning
 	let (first, last) = match pruning_range(config, min_blocks_to_keep, current_block.number.clone()) {
@@ -116,7 +116,7 @@ fn prune_trie<S: Storage<H, Number>, H: Hasher, Number: BlockNumber, F: FnMut(H:
 	storage: &S,
 	root: H::Out,
 	remove_trie_node: &mut F,
-) {
+) where H::Out: Codec {
 
 	// enumerate all changes trie' keys, recording all nodes that have been 'touched'
 	// (effectively - all changes trie nodes)
@@ -221,13 +221,15 @@ mod tests {
 		storage: &S,
 		min_blocks_to_keep: u64,
 		current_block: u64,
-	) -> HashSet<H::Out> {
+	) -> HashSet<H::Out> where H::Out: Codec {
 		let mut pruned_trie_nodes = HashSet::new();
-		prune(config,
+		prune(
+			config,
 			storage,
 			min_blocks_to_keep,
 			&AnchorBlockId { hash: Default::default(), number: current_block },
-			|node| { pruned_trie_nodes.insert(node); });
+			|node| { pruned_trie_nodes.insert(node); },
+		);
 		pruned_trie_nodes
 	}