More Span simplifications

Based on suggestions by MarcoFalke <falke.marco@gmail.com>

src/net.cpp

@@ -760,7 +760,7 @@ CNetMessage V1TransportDeserializer::GetMessage(const std::chrono::microseconds
     if (memcmp(hash.begin(), hdr.pchChecksum, CMessageHeader::CHECKSUM_SIZE) != 0) {
         LogPrint(BCLog::NET, "Header error: Wrong checksum (%s, %u bytes), expected %s was %s, peer=%d\n",
                  SanitizeString(msg.m_command), msg.m_message_size,
-                 HexStr(Span<uint8_t>(hash.begin(), hash.begin() + CMessageHeader::CHECKSUM_SIZE)),
+                 HexStr(Span{hash}.first(CMessageHeader::CHECKSUM_SIZE)),
                  HexStr(hdr.pchChecksum),
                  m_node_id);
         reject_message = true;
@@ -1582,8 +1582,9 @@ void CConnman::SocketHandlerConnected(const std::vector<CNode*>& nodes,
             if (nBytes > 0)
             {
                 bool notify = false;
-                if (!pnode->ReceiveMsgBytes(Span<const uint8_t>(pchBuf, nBytes), notify))
+                if (!pnode->ReceiveMsgBytes({pchBuf, (size_t)nBytes}, notify)) {
                     pnode->CloseSocketDisconnect();
+                }
                 RecordBytesRecv(nBytes);
                 if (notify) {
                     size_t nSizeAdded = 0;

src/netaddress.cpp

@@ -303,7 +303,7 @@ CNetAddr::CNetAddr(const struct in_addr& ipv4Addr)
 
 CNetAddr::CNetAddr(const struct in6_addr& ipv6Addr, const uint32_t scope)
 {
-    SetLegacyIPv6(Span<const uint8_t>(reinterpret_cast<const uint8_t*>(&ipv6Addr), sizeof(ipv6Addr)));
+    SetLegacyIPv6({reinterpret_cast<const uint8_t*>(&ipv6Addr), sizeof(ipv6Addr)});
     m_scope_id = scope;
 }
 

src/pubkey.h

@@ -240,7 +240,7 @@ public:
     explicit XOnlyPubKey(Span<const unsigned char> bytes);
 
     /** Construct an x-only pubkey from a normal pubkey. */
-    explicit XOnlyPubKey(const CPubKey& pubkey) : XOnlyPubKey(Span<const unsigned char>(pubkey.begin() + 1, pubkey.begin() + 33)) {}
+    explicit XOnlyPubKey(const CPubKey& pubkey) : XOnlyPubKey(Span{pubkey}.subspan(1, 32)) {}
 
     /** Verify a Schnorr signature against this public key.
      *

src/rpc/util.cpp

@@ -317,7 +317,7 @@ public:
         UniValue obj(UniValue::VOBJ);
         obj.pushKV("iswitness", true);
         obj.pushKV("witness_version", (int)id.version);
-        obj.pushKV("witness_program", HexStr(Span<const unsigned char>(id.program, id.length)));
+        obj.pushKV("witness_program", HexStr({id.program, id.length}));
         return obj;
     }
 };

src/script/descriptor.cpp

@@ -1252,7 +1252,7 @@ std::unique_ptr<PubkeyProvider> InferXOnlyPubkey(const XOnlyPubKey& xkey, ParseS
 std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptContext ctx, const SigningProvider& provider)
 {
     if (ctx == ParseScriptContext::P2TR && script.size() == 34 && script[0] == 32 && script[33] == OP_CHECKSIG) {
-        XOnlyPubKey key{Span<const unsigned char>{script.data() + 1, script.data() + 33}};
+        XOnlyPubKey key{Span{script}.subspan(1, 32)};
         return std::make_unique<PKDescriptor>(InferXOnlyPubkey(key, ctx, provider));
     }
 

src/script/interpreter.cpp

@@ -1858,7 +1858,7 @@ uint256 ComputeTaprootMerkleRoot(Span<const unsigned char> control, const uint25
     uint256 k = tapleaf_hash;
     for (int i = 0; i < path_len; ++i) {
         CHashWriter ss_branch{HASHER_TAPBRANCH};
-        Span<const unsigned char> node(control.data() + TAPROOT_CONTROL_BASE_SIZE + TAPROOT_CONTROL_NODE_SIZE * i, TAPROOT_CONTROL_NODE_SIZE);
+        Span node{Span{control}.subspan(TAPROOT_CONTROL_BASE_SIZE + TAPROOT_CONTROL_NODE_SIZE * i, TAPROOT_CONTROL_NODE_SIZE)};
         if (std::lexicographical_compare(k.begin(), k.end(), node.begin(), node.end())) {
             ss_branch << k << node;
         } else {
@@ -1874,7 +1874,7 @@ static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, c
     assert(control.size() >= TAPROOT_CONTROL_BASE_SIZE);
     assert(program.size() >= uint256::size());
     //! The internal pubkey (x-only, so no Y coordinate parity).
-    const XOnlyPubKey p{Span<const unsigned char>{control.data() + 1, control.data() + TAPROOT_CONTROL_BASE_SIZE}};
+    const XOnlyPubKey p{Span{control}.subspan(1, TAPROOT_CONTROL_BASE_SIZE - 1)};
     //! The output pubkey (taken from the scriptPubKey).
     const XOnlyPubKey q{program};
     // Compute the Merkle root from the leaf and the provided path.
@@ -1886,7 +1886,7 @@ static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, c
 static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, const std::vector<unsigned char>& program, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror, bool is_p2sh)
 {
     CScript exec_script; //!< Actually executed script (last stack item in P2WSH; implied P2PKH script in P2WPKH; leaf script in P2TR)
-    Span<const valtype> stack{witness.stack};
+    Span stack{witness.stack};
     ScriptExecutionData execdata;
 
     if (witversion == 0) {

src/signet.cpp

@@ -38,7 +38,7 @@ static bool FetchAndClearCommitmentSection(const Span<const uint8_t> header, CSc
     std::vector<uint8_t> pushdata;
     while (witness_commitment.GetOp(pc, opcode, pushdata)) {
         if (pushdata.size() > 0) {
-            if (!found_header && pushdata.size() > (size_t) header.size() && Span<const uint8_t>(pushdata.data(), header.size()) == header) {
+            if (!found_header && pushdata.size() > (size_t)header.size() && Span{pushdata}.first(header.size()) == header) {
                 // pushdata only counts if it has the header _and_ some data
                 result.insert(result.end(), pushdata.begin() + header.size(), pushdata.end());
                 pushdata.erase(pushdata.begin() + header.size(), pushdata.end());

src/span.h

@@ -258,12 +258,12 @@ Span<std::byte> AsWritableBytes(Span<T> s) noexcept
 template <typename V>
 Span<const std::byte> MakeByteSpan(V&& v) noexcept
 {
-    return AsBytes(MakeSpan(std::forward<V>(v)));
+    return AsBytes(Span{std::forward<V>(v)});
 }
 template <typename V>
 Span<std::byte> MakeWritableByteSpan(V&& v) noexcept
 {
-    return AsWritableBytes(MakeSpan(std::forward<V>(v)));
+    return AsWritableBytes(Span{std::forward<V>(v)});
 }
 
 // Helper functions to safely cast to unsigned char pointers.

src/test/fuzz/asmap.cpp

@@ -49,7 +49,7 @@ FUZZ_TARGET(asmap)
     CNetAddr net_addr;
     if (ipv6) {
         assert(addr_size == ADDR_IPV6_SIZE);
-        net_addr.SetLegacyIPv6(Span<const uint8_t>(addr_data, addr_size));
+        net_addr.SetLegacyIPv6({addr_data, addr_size});
     } else {
         assert(addr_size == ADDR_IPV4_SIZE);
         in_addr ipv4;

src/test/fuzz/utxo_snapshot.cpp

@@ -38,7 +38,7 @@ FUZZ_TARGET_INIT(utxo_snapshot, initialize_chain)
     {
         CAutoFile outfile{fsbridge::fopen(snapshot_path, "wb"), SER_DISK, CLIENT_VERSION};
         const auto file_data{ConsumeRandomLengthByteVector(fuzzed_data_provider)};
-        outfile << Span<const uint8_t>{file_data};
+        outfile << Span{file_data};
     }
 
     const auto ActivateFuzzedSnapshot{[&] {

src/test/key_io_tests.cpp

@@ -46,7 +46,7 @@ BOOST_AUTO_TEST_CASE(key_io_valid_parse)
             privkey = DecodeSecret(exp_base58string);
             BOOST_CHECK_MESSAGE(privkey.IsValid(), "!IsValid:" + strTest);
             BOOST_CHECK_MESSAGE(privkey.IsCompressed() == isCompressed, "compressed mismatch:" + strTest);
-            BOOST_CHECK_MESSAGE(Span<const uint8_t>{privkey} == Span<const uint8_t>{exp_payload}, "key mismatch:" + strTest);
+            BOOST_CHECK_MESSAGE(Span{privkey} == Span{exp_payload}, "key mismatch:" + strTest);
 
             // Private key must be invalid public key
             destination = DecodeDestination(exp_base58string);

src/test/util_tests.cpp

@@ -142,13 +142,11 @@ BOOST_AUTO_TEST_CASE(util_HexStr)
         "04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f");
 
     BOOST_CHECK_EQUAL(
-        HexStr(Span<const unsigned char>(
+        HexStr(Span{ParseHex_expected}.last(0)),
-               ParseHex_expected + sizeof(ParseHex_expected),
-               ParseHex_expected + sizeof(ParseHex_expected))),
         "");
 
     BOOST_CHECK_EQUAL(
-        HexStr(Span<const unsigned char>(ParseHex_expected, ParseHex_expected)),
+        HexStr(Span{ParseHex_expected}.first(0)),
         "");
 
     {

src/wallet/rpcdump.cpp

@@ -35,7 +35,7 @@ std::string static EncodeDumpString(const std::string &str) {
     std::stringstream ret;
     for (const unsigned char c : str) {
         if (c <= 32 || c >= 128 || c == '%') {
-            ret << '%' << HexStr(Span<const unsigned char>(&c, 1));
+            ret << '%' << HexStr({&c, 1});
         } else {
             ret << c;
         }

src/wallet/rpcwallet.cpp

@@ -4937,5 +4937,5 @@ static const CRPCCommand commands[] =
     { "wallet",             &walletprocesspsbt,              },
 };
 // clang-format on
-    return Span{commands};
+    return commands;
 }