Merge #20464: refactor: Treat CDataStream bytes as uint8_t

fa292724598c273867bc6dbf311f1440fe2541ba Remove redundant MakeUCharSpan wrappers (MarcoFalke)
faf4aa2f47c0de4f3a0c5f5fe5b3ec32f611eefd Remove CDataStream::Init in favor of C++11 member initialization (MarcoFalke)
fada14b948cac147198e3b685b5dd8cb72dc2911 Treat CDataStream bytes as uint8_t (MarcoFalke)
fa8bdb048e65cae2d26bea3f991717a856e2fb39 refactor: Drop CDataStream constructors in favor of one taking a Span of bytes (MarcoFalke)
faa96f841fe45bc49ebb6e07ac82a129fa9c40bf Remove unused CDataStream methods (MarcoFalke)

Pull request description:

  Using `uint8_t` for raw bytes has a style benefit:
  * The signedness is clear from reading the code, as it does not depend on the architecture

  Other clean-ups in this pull include:
  * Remove unused methods
  * Constructor is simplified with `Span`
  * Remove `Init()` member in favor of C++11 member initialization

ACKs for top commit:
  laanwj:
    code review ACK fa292724598c273867bc6dbf311f1440fe2541ba
  theStack:
    ACK fa292724598c273867bc6dbf311f1440fe2541ba 🍾

Tree-SHA512: 931ee28bd99843d7e894b48e90e1187ffb0278677c267044b3c0c255069d9bbd9298ab2e539b1002a30b543d240450eaec718ef4ee95a7fd4be0a295e926343f

13 files changed, 63 insertions, 122 deletions

diff --git a/src/bench/prevector.cpp b/src/bench/prevector.cpp
index dcd0e10285..f4fabedab6 100644
--- a/src/bench/prevector.cpp
+++ b/src/bench/prevector.cpp
@@ -76,7 +76,7 @@ static void PrevectorDeserialize(benchmark::Bench& bench)
         for (auto x = 0; x < 1000; ++x) {
             s0 >> t1;
         }
-        s0.Init(SER_NETWORK, 0);
+        s0.Rewind();
     });
 }
 
diff --git a/src/dbwrapper.h b/src/dbwrapper.h
index 33e4b366a1..c119036db2 100644
--- a/src/dbwrapper.h
+++ b/src/dbwrapper.h
@@ -8,9 +8,10 @@
 #include <clientversion.h>
 #include <fs.h>
 #include <serialize.h>
+#include <span.h>
 #include <streams.h>
-#include <util/system.h>
 #include <util/strencodings.h>
+#include <util/system.h>
 
 #include <leveldb/db.h>
 #include <leveldb/write_batch.h>
@@ -73,12 +74,12 @@ public:
     {
         ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey << key;
-        leveldb::Slice slKey(ssKey.data(), ssKey.size());
+        leveldb::Slice slKey((const char*)ssKey.data(), ssKey.size());
 
         ssValue.reserve(DBWRAPPER_PREALLOC_VALUE_SIZE);
         ssValue << value;
         ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
-        leveldb::Slice slValue(ssValue.data(), ssValue.size());
+        leveldb::Slice slValue((const char*)ssValue.data(), ssValue.size());
 
         batch.Put(slKey, slValue);
         // LevelDB serializes writes as:
@@ -98,7 +99,7 @@ public:
     {
         ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey << key;
-        leveldb::Slice slKey(ssKey.data(), ssKey.size());
+        leveldb::Slice slKey((const char*)ssKey.data(), ssKey.size());
 
         batch.Delete(slKey);
         // LevelDB serializes erases as:
@@ -137,7 +138,7 @@ public:
         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
         ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey << key;
-        leveldb::Slice slKey(ssKey.data(), ssKey.size());
+        leveldb::Slice slKey((const char*)ssKey.data(), ssKey.size());
         piter->Seek(slKey);
     }
 
@@ -146,7 +147,7 @@ public:
     template<typename K> bool GetKey(K& key) {
         leveldb::Slice slKey = piter->key();
         try {
-            CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
+            CDataStream ssKey(MakeUCharSpan(slKey), SER_DISK, CLIENT_VERSION);
             ssKey >> key;
         } catch (const std::exception&) {
             return false;
@@ -157,7 +158,7 @@ public:
     template<typename V> bool GetValue(V& value) {
         leveldb::Slice slValue = piter->value();
         try {
-            CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
+            CDataStream ssValue(MakeUCharSpan(slValue), SER_DISK, CLIENT_VERSION);
             ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
             ssValue >> value;
         } catch (const std::exception&) {
@@ -232,7 +233,7 @@ public:
         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
         ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey << key;
-        leveldb::Slice slKey(ssKey.data(), ssKey.size());
+        leveldb::Slice slKey((const char*)ssKey.data(), ssKey.size());
 
         std::string strValue;
         leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
@@ -243,7 +244,7 @@ public:
             dbwrapper_private::HandleError(status);
         }
         try {
-            CDataStream ssValue(strValue.data(), strValue.data() + strValue.size(), SER_DISK, CLIENT_VERSION);
+            CDataStream ssValue(MakeUCharSpan(strValue), SER_DISK, CLIENT_VERSION);
             ssValue.Xor(obfuscate_key);
             ssValue >> value;
         } catch (const std::exception&) {
@@ -266,7 +267,7 @@ public:
         CDataStream ssKey(SER_DISK, CLIENT_VERSION);
         ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey << key;
-        leveldb::Slice slKey(ssKey.data(), ssKey.size());
+        leveldb::Slice slKey((const char*)ssKey.data(), ssKey.size());
 
         std::string strValue;
         leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
@@ -310,8 +311,8 @@ public:
         ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey1 << key_begin;
         ssKey2 << key_end;
-        leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
-        leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
+        leveldb::Slice slKey1((const char*)ssKey1.data(), ssKey1.size());
+        leveldb::Slice slKey2((const char*)ssKey2.data(), ssKey2.size());
         uint64_t size = 0;
         leveldb::Range range(slKey1, slKey2);
         pdb->GetApproximateSizes(&range, 1, &size);
@@ -329,11 +330,10 @@ public:
         ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
         ssKey1 << key_begin;
         ssKey2 << key_end;
-        leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
-        leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
+        leveldb::Slice slKey1((const char*)ssKey1.data(), ssKey1.size());
+        leveldb::Slice slKey2((const char*)ssKey2.data(), ssKey2.size());
         pdb->CompactRange(&slKey1, &slKey2);
     }
-
 };
 
 #endif // BITCOIN_DBWRAPPER_H
diff --git a/src/psbt.cpp b/src/psbt.cpp
index 4db57d3cd0..a849b2ea53 100644
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -363,7 +363,7 @@ bool DecodeBase64PSBT(PartiallySignedTransaction& psbt, const std::string& base6
 
 bool DecodeRawPSBT(PartiallySignedTransaction& psbt, const std::string& tx_data, std::string& error)
 {
-    CDataStream ss_data(tx_data.data(), tx_data.data() + tx_data.size(), SER_NETWORK, PROTOCOL_VERSION);
+    CDataStream ss_data(MakeUCharSpan(tx_data), SER_NETWORK, PROTOCOL_VERSION);
     try {
         ss_data >> psbt;
         if (!ss_data.empty()) {
diff --git a/src/qt/recentrequeststablemodel.cpp b/src/qt/recentrequeststablemodel.cpp
index 18b913774b..03531a1381 100644
--- a/src/qt/recentrequeststablemodel.cpp
+++ b/src/qt/recentrequeststablemodel.cpp
@@ -181,7 +181,7 @@ void RecentRequestsTableModel::addNewRequest(const SendCoinsRecipient &recipient
 // called from ctor when loading from wallet
 void RecentRequestsTableModel::addNewRequest(const std::string &recipient)
 {
-    std::vector<char> data(recipient.begin(), recipient.end());
+    std::vector<uint8_t> data(recipient.begin(), recipient.end());
     CDataStream ss(data, SER_DISK, CLIENT_VERSION);
 
     RecentRequestEntry entry;
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index 58427b42cc..02254da3ce 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -245,7 +245,7 @@ WalletModel::SendCoinsReturn WalletModel::sendCoins(WalletModelTransaction &tran
 
         CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
         ssTx << *newTx;
-        transaction_array.append(&(ssTx[0]), ssTx.size());
+        transaction_array.append((const char*)&(ssTx[0]), ssTx.size());
     }
 
     // Add addresses / update labels that we've sent to the address book,
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index e478f12ab5..ac42404470 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1345,7 +1345,7 @@ static RPCHelpMan combinepsbt()
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << merged_psbt;
-    return EncodeBase64(MakeUCharSpan(ssTx));
+    return EncodeBase64(ssTx);
 },
     };
 }
@@ -1484,7 +1484,7 @@ static RPCHelpMan createpsbt()
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << psbtx;
 
-    return EncodeBase64(MakeUCharSpan(ssTx));
+    return EncodeBase64(ssTx);
 },
     };
 }
@@ -1553,7 +1553,7 @@ static RPCHelpMan converttopsbt()
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << psbtx;
 
-    return EncodeBase64(MakeUCharSpan(ssTx));
+    return EncodeBase64(ssTx);
 },
     };
 }
@@ -1644,7 +1644,7 @@ static RPCHelpMan utxoupdatepsbt()
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << psbtx;
-    return EncodeBase64(MakeUCharSpan(ssTx));
+    return EncodeBase64(ssTx);
 },
     };
 }
@@ -1740,7 +1740,7 @@ static RPCHelpMan joinpsbts()
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << shuffled_psbt;
-    return EncodeBase64(MakeUCharSpan(ssTx));
+    return EncodeBase64(ssTx);
 },
     };
 }
diff --git a/src/streams.h b/src/streams.h
index fce411d3df..e78da31cbc 100644
--- a/src/streams.h
+++ b/src/streams.h
@@ -6,17 +6,19 @@
 #ifndef BITCOIN_STREAMS_H
 #define BITCOIN_STREAMS_H
 
-#include <support/allocators/zeroafterfree.h>
 #include <serialize.h>
+#include <span.h>
+#include <support/allocators/zeroafterfree.h>
 
 #include <algorithm>
 #include <assert.h>
 #include <ios>
 #include <limits>
+#include <optional>
 #include <stdint.h>
 #include <stdio.h>
-#include <string>
 #include <string.h>
+#include <string>
 #include <utility>
 #include <vector>
 
@@ -202,14 +204,14 @@ public:
 class CDataStream
 {
 protected:
-    typedef CSerializeData vector_type;
+    using vector_type = SerializeData;
     vector_type vch;
-    unsigned int nReadPos;
+    unsigned int nReadPos{0};
 
     int nType;
     int nVersion;
-public:
 
+public:
     typedef vector_type::allocator_type   allocator_type;
     typedef vector_type::size_type        size_type;
     typedef vector_type::difference_type  difference_type;
@@ -221,62 +223,22 @@ public:
     typedef vector_type::reverse_iterator reverse_iterator;
 
     explicit CDataStream(int nTypeIn, int nVersionIn)
-    {
-        Init(nTypeIn, nVersionIn);
-    }
-
-    CDataStream(const_iterator pbegin, const_iterator pend, int nTypeIn, int nVersionIn) : vch(pbegin, pend)
-    {
-        Init(nTypeIn, nVersionIn);
-    }
-
-    CDataStream(const char* pbegin, const char* pend, int nTypeIn, int nVersionIn) : vch(pbegin, pend)
-    {
-        Init(nTypeIn, nVersionIn);
-    }
-
-    CDataStream(const vector_type& vchIn, int nTypeIn, int nVersionIn) : vch(vchIn.begin(), vchIn.end())
-    {
-        Init(nTypeIn, nVersionIn);
-    }
-
-    CDataStream(const std::vector<char>& vchIn, int nTypeIn, int nVersionIn) : vch(vchIn.begin(), vchIn.end())
-    {
-        Init(nTypeIn, nVersionIn);
-    }
+        : nType{nTypeIn},
+          nVersion{nVersionIn} {}
 
-    CDataStream(const std::vector<unsigned char>& vchIn, int nTypeIn, int nVersionIn) : vch(vchIn.begin(), vchIn.end())
-    {
-        Init(nTypeIn, nVersionIn);
-    }
+    explicit CDataStream(Span<const uint8_t> sp, int nTypeIn, int nVersionIn)
+        : vch(sp.data(), sp.data() + sp.size()),
+          nType{nTypeIn},
+          nVersion{nVersionIn} {}
 
     template <typename... Args>
     CDataStream(int nTypeIn, int nVersionIn, Args&&... args)
+        : nType{nTypeIn},
+          nVersion{nVersionIn}
     {
-        Init(nTypeIn, nVersionIn);
         ::SerializeMany(*this, std::forward<Args>(args)...);
     }
 
-    void Init(int nTypeIn, int nVersionIn)
-    {
-        nReadPos = 0;
-        nType = nTypeIn;
-        nVersion = nVersionIn;
-    }
-
-    CDataStream& operator+=(const CDataStream& b)
-    {
-        vch.insert(vch.end(), b.begin(), b.end());
-        return *this;
-    }
-
-    friend CDataStream operator+(const CDataStream& a, const CDataStream& b)
-    {
-        CDataStream ret = a;
-        ret += b;
-        return (ret);
-    }
-
     std::string str() const
     {
         return (std::string(begin(), end()));
@@ -297,12 +259,12 @@ public:
     const_reference operator[](size_type pos) const  { return vch[pos + nReadPos]; }
     reference operator[](size_type pos)              { return vch[pos + nReadPos]; }
     void clear()                                     { vch.clear(); nReadPos = 0; }
-    iterator insert(iterator it, const char x=char()) { return vch.insert(it, x); }
-    void insert(iterator it, size_type n, const char x) { vch.insert(it, n, x); }
+    iterator insert(iterator it, const uint8_t x) { return vch.insert(it, x); }
+    void insert(iterator it, size_type n, const uint8_t x) { vch.insert(it, n, x); }
     value_type* data()                               { return vch.data() + nReadPos; }
     const value_type* data() const                   { return vch.data() + nReadPos; }
 
-    void insert(iterator it, std::vector<char>::const_iterator first, std::vector<char>::const_iterator last)
+    void insert(iterator it, std::vector<uint8_t>::const_iterator first, std::vector<uint8_t>::const_iterator last)
     {
         if (last == first) return;
         assert(last - first > 0);
@@ -373,12 +335,17 @@ public:
         nReadPos = 0;
     }
 
-    bool Rewind(size_type n)
+    bool Rewind(std::optional<size_type> n = std::nullopt)
     {
+        // Total rewind if no size is passed
+        if (!n) {
+            nReadPos = 0;
+            return true;
+        }
         // Rewind by n characters if the buffer hasn't been compacted yet
-        if (n > nReadPos)
+        if (*n > nReadPos)
             return false;
-        nReadPos -= n;
+        nReadPos -= *n;
         return true;
     }
 
@@ -462,11 +429,6 @@ public:
         return (*this);
     }
 
-    void GetAndClear(CSerializeData &d) {
-        d.insert(d.end(), begin(), end());
-        clear();
-    }
-
     /**
      * XOR the contents of this stream with a certain key.
      *
diff --git a/src/support/allocators/zeroafterfree.h b/src/support/allocators/zeroafterfree.h
index c7ed5ef308..418f0ee656 100644
--- a/src/support/allocators/zeroafterfree.h
+++ b/src/support/allocators/zeroafterfree.h
@@ -42,7 +42,7 @@ struct zero_after_free_allocator : public std::allocator<T> {
     }
 };
 
-// Byte-vector that clears its contents before deletion.
-typedef std::vector<char, zero_after_free_allocator<char> > CSerializeData;
+/** Byte-vector that clears its contents before deletion. */
+using SerializeData = std::vector<uint8_t, zero_after_free_allocator<uint8_t>>;
 
 #endif // BITCOIN_SUPPORT_ALLOCATORS_ZEROAFTERFREE_H
diff --git a/src/test/bloom_tests.cpp b/src/test/bloom_tests.cpp
index 736c260eeb..5a98558240 100644
--- a/src/test/bloom_tests.cpp
+++ b/src/test/bloom_tests.cpp
@@ -42,11 +42,7 @@ BOOST_AUTO_TEST_CASE(bloom_create_insert_serialize)
     CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
     stream << filter;
 
-    std::vector<unsigned char> vch = ParseHex("03614e9b050000000000000001");
-    std::vector<char> expected(vch.size());
-
-    for (unsigned int i = 0; i < vch.size(); i++)
-        expected[i] = (char)vch[i];
+    std::vector<uint8_t> expected = ParseHex("03614e9b050000000000000001");
 
     BOOST_CHECK_EQUAL_COLLECTIONS(stream.begin(), stream.end(), expected.begin(), expected.end());
 
@@ -72,11 +68,7 @@ BOOST_AUTO_TEST_CASE(bloom_create_insert_serialize_with_tweak)
     CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
     stream << filter;
 
-    std::vector<unsigned char> vch = ParseHex("03ce4299050000000100008001");
-    std::vector<char> expected(vch.size());
-
-    for (unsigned int i = 0; i < vch.size(); i++)
-        expected[i] = (char)vch[i];
+    std::vector<uint8_t> expected = ParseHex("03ce4299050000000100008001");
 
     BOOST_CHECK_EQUAL_COLLECTIONS(stream.begin(), stream.end(), expected.begin(), expected.end());
 }
@@ -96,11 +88,7 @@ BOOST_AUTO_TEST_CASE(bloom_create_insert_key)
     CDataStream stream(SER_NETWORK, PROTOCOL_VERSION);
     stream << filter;
 
-    std::vector<unsigned char> vch = ParseHex("038fc16b080000000000000001");
-    std::vector<char> expected(vch.size());
-
-    for (unsigned int i = 0; i < vch.size(); i++)
-        expected[i] = (char)vch[i];
+    std::vector<unsigned char> expected = ParseHex("038fc16b080000000000000001");
 
     BOOST_CHECK_EQUAL_COLLECTIONS(stream.begin(), stream.end(), expected.begin(), expected.end());
 }
@@ -352,11 +340,7 @@ BOOST_AUTO_TEST_CASE(merkle_block_3_and_serialize)
     CDataStream merkleStream(SER_NETWORK, PROTOCOL_VERSION);
     merkleStream << merkleBlock;
 
-    std::vector<unsigned char> vch = ParseHex("0100000079cda856b143d9db2c1caff01d1aecc8630d30625d10e8b4b8b0000000000000b50cc069d6a3e33e3ff84a5c41d9d3febe7c770fdcc96b2c3ff60abe184f196367291b4d4c86041b8fa45d630100000001b50cc069d6a3e33e3ff84a5c41d9d3febe7c770fdcc96b2c3ff60abe184f19630101");
-    std::vector<char> expected(vch.size());
-
-    for (unsigned int i = 0; i < vch.size(); i++)
-        expected[i] = (char)vch[i];
+    std::vector<uint8_t> expected = ParseHex("0100000079cda856b143d9db2c1caff01d1aecc8630d30625d10e8b4b8b0000000000000b50cc069d6a3e33e3ff84a5c41d9d3febe7c770fdcc96b2c3ff60abe184f196367291b4d4c86041b8fa45d630100000001b50cc069d6a3e33e3ff84a5c41d9d3febe7c770fdcc96b2c3ff60abe184f19630101");
 
     BOOST_CHECK_EQUAL_COLLECTIONS(expected.begin(), expected.end(), merkleStream.begin(), merkleStream.end());
 }
diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index e48771efa2..7a2dcfe84a 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -61,7 +61,7 @@ void CallOneOf(FuzzedDataProvider& fuzzed_data_provider, Callables... callables)
 
 [[nodiscard]] inline CDataStream ConsumeDataStream(FuzzedDataProvider& fuzzed_data_provider, const size_t max_length = 4096) noexcept
 {
-    return {ConsumeRandomLengthByteVector(fuzzed_data_provider, max_length), SER_NETWORK, INIT_PROTO_VERSION};
+    return CDataStream{ConsumeRandomLengthByteVector(fuzzed_data_provider, max_length), SER_NETWORK, INIT_PROTO_VERSION};
 }
 
 [[nodiscard]] inline std::vector<std::string> ConsumeRandomLengthStringVector(FuzzedDataProvider& fuzzed_data_provider, const size_t max_vector_size = 16, const size_t max_string_length = 16) noexcept
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index f625b67c2a..f77cda7ba2 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -320,7 +320,7 @@ BOOST_AUTO_TEST_CASE(insert_delete)
 
     ss.insert(ss.end(), c);
     BOOST_CHECK_EQUAL(ss.size(), 6U);
-    BOOST_CHECK_EQUAL(ss[4], (char)0xff);
+    BOOST_CHECK_EQUAL(ss[4], 0xff);
     BOOST_CHECK_EQUAL(ss[5], c);
 
     ss.insert(ss.begin()+2, c);
@@ -334,19 +334,14 @@ BOOST_AUTO_TEST_CASE(insert_delete)
 
     ss.erase(ss.begin()+ss.size()-1);
     BOOST_CHECK_EQUAL(ss.size(), 5U);
-    BOOST_CHECK_EQUAL(ss[4], (char)0xff);
+    BOOST_CHECK_EQUAL(ss[4], 0xff);
 
     ss.erase(ss.begin()+1);
     BOOST_CHECK_EQUAL(ss.size(), 4U);
     BOOST_CHECK_EQUAL(ss[0], 0);
     BOOST_CHECK_EQUAL(ss[1], 1);
     BOOST_CHECK_EQUAL(ss[2], 2);
-    BOOST_CHECK_EQUAL(ss[3], (char)0xff);
-
-    // Make sure GetAndClear does the right thing:
-    CSerializeData d;
-    ss.GetAndClear(d);
-    BOOST_CHECK_EQUAL(ss.size(), 0U);
+    BOOST_CHECK_EQUAL(ss[3], 0xff);
 }
 
 BOOST_AUTO_TEST_CASE(class_methods)
diff --git a/src/test/streams_tests.cpp b/src/test/streams_tests.cpp
index 8f5ee1e8e2..3079c9ff29 100644
--- a/src/test/streams_tests.cpp
+++ b/src/test/streams_tests.cpp
@@ -149,7 +149,7 @@ BOOST_AUTO_TEST_CASE(bitstream_reader_writer)
 
 BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
 {
-    std::vector<char> in;
+    std::vector<uint8_t> in;
     std::vector<char> expected_xor;
     std::vector<unsigned char> key;
     CDataStream ds(in, 0, 0);
diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index c0d107bf39..ad40e6da9a 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -488,9 +488,9 @@ bool BerkeleyDatabase::Rewrite(const char* pszSkip)
                                 break;
                             }
                             if (pszSkip &&
-                                strncmp(ssKey.data(), pszSkip, std::min(ssKey.size(), strlen(pszSkip))) == 0)
+                                strncmp((const char*)ssKey.data(), pszSkip, std::min(ssKey.size(), strlen(pszSkip))) == 0)
                                 continue;
-                            if (strncmp(ssKey.data(), "\x07version", 8) == 0) {
+                            if (strncmp((const char*)ssKey.data(), "\x07version", 8) == 0) {
                                 // Update version:
                                 ssValue.clear();
                                 ssValue << CLIENT_VERSION;