Make HashDB generic (#8739)

The `patricia_trie` crate is generic over the hasher (by way of HashDB) and node encoding scheme. Adds a new `patricia_trie_ethereum` crate with concrete impls for Keccak/RLP.

ethcore/vm/Cargo.toml

@@ -8,6 +8,7 @@ byteorder = "1.0"
 ethcore-bytes = { path = "../../util/bytes" }
 ethereum-types = "0.3"
 patricia-trie = { path = "../../util/patricia_trie" }
+patricia-trie-ethereum = { path = "../../util/patricia-trie-ethereum" }
 log = "0.3"
 common-types = { path = "../types" }
 ethjson = { path = "../../json" }

ethcore/vm/src/error.rs

@@ -16,8 +16,8 @@
 
 //! VM errors module
 
-use trie;
 use std::fmt;
+use ethtrie;
 
 /// VM errors.
 #[derive(Debug, Clone, PartialEq)]
@@ -71,8 +71,13 @@ pub enum Error {
 	Reverted,
 }
 
-impl From<Box<trie::TrieError>> for Error {
-	fn from(err: Box<trie::TrieError>) -> Self {
+impl From<Box<ethtrie::TrieError>> for Error {
+	fn from(err: Box<ethtrie::TrieError>) -> Self {
+		Error::Internal(format!("Internal error: {}", err))
+	}
+}
+impl From<ethtrie::TrieError> for Error {
+	fn from(err: ethtrie::TrieError) -> Self {
 		Error::Internal(format!("Internal error: {}", err))
 	}
 }

ethcore/vm/src/lib.rs

@@ -22,6 +22,7 @@ extern crate common_types as types;
 extern crate ethjson;
 extern crate rlp;
 extern crate keccak_hash as hash;
+extern crate patricia_trie_ethereum as ethtrie;
 extern crate patricia_trie as trie;
 
 mod action_params;