core: fix Hash::from_hex (#1279)

silkworm/core/types/hash.hpp

@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <optional>
 #include <span>
 #include <string>
 
@@ -41,7 +42,7 @@ class Hash : public evmc::bytes32 {
     static constexpr size_t length() { return sizeof(evmc::bytes32); }
 
     [[nodiscard]] std::string to_hex() const { return silkworm::to_hex(*this); }
-    static Hash from_hex(const std::string& hex) { return {evmc::from_hex<Hash>(hex).value()}; }
+    static std::optional<Hash> from_hex(const std::string& hex) { return evmc::from_hex<Hash>(hex); }
 
     // conversion to ByteView is handled in ByteView class,
     // conversion operator Byte() { return {bytes, length()}; } is handled elsewhere
@@ -52,17 +53,6 @@ class Hash : public evmc::bytes32 {
 using HashAsSpan = std::span<const uint8_t, kHashLength>;
 using HashAsArray = const uint8_t (&)[kHashLength];
 
-// RLP encoding: usually same as ByteView, some tricks for MSVC overload resolution
-namespace rlp {
-    inline size_t length_hash(const Hash&) { return kHashLength + 1; }
-
-    void encode_hash(Bytes& to, const Hash& h);
-
-    // template <>
-    DecodingResult decode_hash(ByteView& from, Hash& to) noexcept;
-
-}  // namespace rlp
-
 }  // namespace silkworm
 
 namespace std {

silkworm/core/types/hash_test.cpp

@@ -0,0 +1,30 @@
+/*
+   Copyright 2023 The Silkworm Authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+#include "hash.hpp"
+
+#include <catch2/catch.hpp>
+
+namespace silkworm {
+
+TEST_CASE("from_hex") {
+    CHECK(Hash::from_hex("foo") == std::nullopt);
+
+    const auto kHashValue{0x2d690516512020171c1ec870f6ff45398cc8609250326be89915fb538e7b_bytes32};
+    CHECK(Hash::from_hex("0x2d690516512020171c1ec870f6ff45398cc8609250326be89915fb538e7b") == kHashValue);
+}
+
+}  // namespace silkworm

silkworm/sync/packets/packet_coding_test.cpp

@@ -65,7 +65,7 @@ TEST_CASE("NewBlockHashesPacket encoding") {
     NewBlockHashesPacket packet;
 
     NewBlockHash newBlock;
-    newBlock.hash = Hash::from_hex("eb2c33963824bf97d01cff8a65f00dc402fbf64f473cb4778a547ac08cebc354");
+    newBlock.hash = *Hash::from_hex("eb2c33963824bf97d01cff8a65f00dc402fbf64f473cb4778a547ac08cebc354");
     newBlock.number = 12'420'112;
     packet.push_back(newBlock);
 
@@ -1026,8 +1026,8 @@ TEST_CASE("GetBlockBodiesPacket (eth/66) encoding") {
     GetBlockBodiesPacket66 packet;
 
     packet.requestId = 0xae9405dbeebf3f01;
-    packet.request.push_back(Hash::from_hex("a36b1595c5acd878b63f83d3b62f6882edd27b757582f5319aebc17bc3e98246"));
-    packet.request.push_back(Hash::from_hex("9f20a871bf5151959fff4c88783bf4ef27b170a4cbe92b8f63ca1fe7d6ab829c"));
+    packet.request.push_back(*Hash::from_hex("a36b1595c5acd878b63f83d3b62f6882edd27b757582f5319aebc17bc3e98246"));
+    packet.request.push_back(*Hash::from_hex("9f20a871bf5151959fff4c88783bf4ef27b170a4cbe92b8f63ca1fe7d6ab829c"));
 
     Bytes encoded;
     rlp::encode(encoded, packet);