Merge #16451: Remove CMerkleTx

05b56d1c937b7667ad51400d2f9fb674af72953f [wallet] Remove CMerkleTx serialization logic (John Newbery)
783a76f23ba4f33b6e6f609eaf3bf41afd9bcd6f [wallet] Flatten CWalletTx class hierarchy (John Newbery)
b3a9d179f23f654b8fba63924bbca5fd31ad4bb0 [wallet] Move CMerkleTx functions into CWalletTx (John Newbery)

Pull request description:

  CMerkleTx is only used as a base class for
  CWalletTx. It was previously also used for vtxPrev which
  was removed in 93a18a3650292afbb441a47d1fa1b94aeb0164e3.

  This PR moves all of the CMerkleTx members and logic
  into CWalletTx. The CMerkleTx class is kept for deserialization
  and serialization of old wallet files.

  This makes the refactor in #15931 cleaner.

ACKs for top commit:
  laanwj:
    ACK 05b56d1c937b7667ad51400d2f9fb674af72953f. Looks good to me.

Tree-SHA512: 3d3a0069ebb536b12a328f1261e7dc55158a71088d445ae4b4ace4142c432dc296f58c8183b1922e54a60b8cc77e9d17c3dce7478294cd68693594baacf2bab3

2 files changed, 72 insertions, 85 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 638ed569c3..11a2154f53 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -228,7 +228,7 @@ WalletCreationStatus CreateWallet(interfaces::Chain& chain, const SecureString&
 
 const uint32_t BIP32_HARDENED_KEY_LIMIT = 0x80000000;
 
-const uint256 CMerkleTx::ABANDON_HASH(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
+const uint256 CWalletTx::ABANDON_HASH(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
 
 /** @defgroup mapWallet
  *
@@ -4627,7 +4627,7 @@ CKeyPool::CKeyPool(const CPubKey& vchPubKeyIn, bool internalIn)
     m_pre_split = false;
 }
 
-void CMerkleTx::SetMerkleBranch(const uint256& block_hash, int posInBlock)
+void CWalletTx::SetMerkleBranch(const uint256& block_hash, int posInBlock)
 {
     // Update the tx's hashBlock
     hashBlock = block_hash;
@@ -4636,7 +4636,7 @@ void CMerkleTx::SetMerkleBranch(const uint256& block_hash, int posInBlock)
     nIndex = posInBlock;
 }
 
-int CMerkleTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
+int CWalletTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
 {
     if (hashUnset())
         return 0;
@@ -4644,7 +4644,7 @@ int CMerkleTx::GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const
     return locked_chain.getBlockDepth(hashBlock) * (nIndex == -1 ? -1 : 1);
 }
 
-int CMerkleTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
+int CWalletTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
 {
     if (!IsCoinBase())
         return 0;
@@ -4653,7 +4653,7 @@ int CMerkleTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
     return std::max(0, (COINBASE_MATURITY+1) - chain_depth);
 }
 
-bool CMerkleTx::IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const
+bool CWalletTx::IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const
 {
     // note GetBlocksToMaturity is 0 for non-coinbase tx
     return GetBlocksToMaturity(locked_chain) > 0;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 06e22895b5..27f7472806 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -364,82 +364,24 @@ struct COutputEntry
     int vout;
 };
 
-/** A transaction with a merkle branch linking it to the block chain. */
+/** Legacy class used for deserializing vtxPrev for backwards compatibility.
+ * vtxPrev was removed in commit 93a18a3650292afbb441a47d1fa1b94aeb0164e3,
+ * but old wallet.dat files may still contain vtxPrev vectors of CMerkleTxs.
+ * These need to get deserialized for field alignment when deserializing
+ * a CWalletTx, but the deserialized values are discarded.**/
 class CMerkleTx
 {
-private:
-  /** Constant used in hashBlock to indicate tx has been abandoned */
-    static const uint256 ABANDON_HASH;
-
 public:
-    CTransactionRef tx;
-    uint256 hashBlock;
-
-    /* An nIndex == -1 means that hashBlock (in nonzero) refers to the earliest
-     * block in the chain we know this or any in-wallet dependency conflicts
-     * with. Older clients interpret nIndex == -1 as unconfirmed for backward
-     * compatibility.
-     */
-    int nIndex;
-
-    CMerkleTx()
-    {
-        SetTx(MakeTransactionRef());
-        Init();
-    }
-
-    explicit CMerkleTx(CTransactionRef arg)
-    {
-        SetTx(std::move(arg));
-        Init();
-    }
-
-    void Init()
-    {
-        hashBlock = uint256();
-        nIndex = -1;
-    }
-
-    void SetTx(CTransactionRef arg)
+    template<typename Stream>
+    void Unserialize(Stream& s)
     {
-        tx = std::move(arg);
-    }
+        CTransactionRef tx;
+        uint256 hashBlock;
+        std::vector<uint256> vMerkleBranch;
+        int nIndex;
 
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action) {
-        std::vector<uint256> vMerkleBranch; // For compatibility with older versions.
-        READWRITE(tx);
-        READWRITE(hashBlock);
-        READWRITE(vMerkleBranch);
-        READWRITE(nIndex);
+        s >> tx >> hashBlock >> vMerkleBranch >> nIndex;
     }
-
-    void SetMerkleBranch(const uint256& block_hash, int posInBlock);
-
-    /**
-     * Return depth of transaction in blockchain:
-     * <0  : conflicts with a transaction this deep in the blockchain
-     *  0  : in memory pool, waiting to be included in a block
-     * >=1 : this many blocks deep in the main chain
-     */
-    int GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const;
-    bool IsInMainChain(interfaces::Chain::Lock& locked_chain) const { return GetDepthInMainChain(locked_chain) > 0; }
-
-    /**
-     * @return number of blocks to maturity for this transaction:
-     *  0 : is not a coinbase transaction, or is a mature coinbase transaction
-     * >0 : is a coinbase transaction which matures in this many blocks
-     */
-    int GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const;
-    bool hashUnset() const { return (hashBlock.IsNull() || hashBlock == ABANDON_HASH); }
-    bool isAbandoned() const { return (hashBlock == ABANDON_HASH); }
-    void setAbandoned() { hashBlock = ABANDON_HASH; }
-
-    const uint256& GetHash() const { return tx->GetHash(); }
-    bool IsCoinBase() const { return tx->IsCoinBase(); }
-    bool IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const;
 };
 
 //Get the marginal bytes of spending the specified output
@@ -449,11 +391,14 @@ int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* pwallet,
  * A transaction with a bunch of additional info that only the owner cares about.
  * It includes any unrecorded transactions needed to link it back to the block chain.
  */
-class CWalletTx : public CMerkleTx
+class CWalletTx
 {
 private:
     const CWallet* pwallet;
 
+  /** Constant used in hashBlock to indicate tx has been abandoned */
+    static const uint256 ABANDON_HASH;
+
 public:
     /**
      * Key/value map with information about the transaction.
@@ -511,7 +456,10 @@ public:
     mutable bool fInMempool;
     mutable CAmount nChangeCached;
 
-    CWalletTx(const CWallet* pwalletIn, CTransactionRef arg) : CMerkleTx(std::move(arg))
+    CWalletTx(const CWallet* pwalletIn, CTransactionRef arg)
+        : tx(std::move(arg)),
+          hashBlock(uint256()),
+          nIndex(-1)
     {
         Init(pwalletIn);
     }
@@ -531,10 +479,18 @@ public:
         nOrderPos = -1;
     }
 
+    CTransactionRef tx;
+    uint256 hashBlock;
+    /* An nIndex == -1 means that hashBlock (in nonzero) refers to the earliest
+     * block in the chain we know this or any in-wallet dependency conflicts
+     * with. Older clients interpret nIndex == -1 as unconfirmed for backward
+     * compatibility.
+     */
+    int nIndex;
+
     template<typename Stream>
     void Serialize(Stream& s) const
     {
-        char fSpent = false;
         mapValue_t mapValueCopy = mapValue;
 
         mapValueCopy["fromaccount"] = "";
@@ -543,20 +499,21 @@ public:
             mapValueCopy["timesmart"] = strprintf("%u", nTimeSmart);
         }
 
-        s << static_cast<const CMerkleTx&>(*this);
-        std::vector<CMerkleTx> vUnused; //!< Used to be vtxPrev
-        s << vUnused << mapValueCopy << vOrderForm << fTimeReceivedIsTxTime << nTimeReceived << fFromMe << fSpent;
+        std::vector<char> dummy_vector1; //!< Used to be vMerkleBranch
+        std::vector<char> dummy_vector2; //!< Used to be vtxPrev
+        char dummy_char = false; //!< Used to be fSpent
+        s << tx << hashBlock << dummy_vector1 << nIndex << dummy_vector2 << mapValueCopy << vOrderForm << fTimeReceivedIsTxTime << nTimeReceived << fFromMe << dummy_char;
     }
 
     template<typename Stream>
     void Unserialize(Stream& s)
     {
         Init(nullptr);
-        char fSpent;
 
-        s >> static_cast<CMerkleTx&>(*this);
-        std::vector<CMerkleTx> vUnused; //!< Used to be vtxPrev
-        s >> vUnused >> mapValue >> vOrderForm >> fTimeReceivedIsTxTime >> nTimeReceived >> fFromMe >> fSpent;
+        std::vector<uint256> dummy_vector1; //!< Used to be vMerkleBranch
+        std::vector<CMerkleTx> dummy_vector2; //!< Used to be vtxPrev
+        char dummy_char; //! Used to be fSpent
+        s >> tx >> hashBlock >> dummy_vector1 >> nIndex >> dummy_vector2 >> mapValue >> vOrderForm >> fTimeReceivedIsTxTime >> nTimeReceived >> fFromMe >> dummy_char;
 
         ReadOrderPos(nOrderPos, mapValue);
         nTimeSmart = mapValue.count("timesmart") ? (unsigned int)atoi64(mapValue["timesmart"]) : 0;
@@ -567,6 +524,11 @@ public:
         mapValue.erase("timesmart");
     }
 
+    void SetTx(CTransactionRef arg)
+    {
+        tx = std::move(arg);
+    }
+
     //! make sure balances are recalculated
     void MarkDirty()
     {
@@ -630,6 +592,31 @@ public:
     // that we still have the runtime check "AssertLockHeld(pwallet->cs_wallet)"
     // in place.
     std::set<uint256> GetConflicts() const NO_THREAD_SAFETY_ANALYSIS;
+
+    void SetMerkleBranch(const uint256& block_hash, int posInBlock);
+
+    /**
+     * Return depth of transaction in blockchain:
+     * <0  : conflicts with a transaction this deep in the blockchain
+     *  0  : in memory pool, waiting to be included in a block
+     * >=1 : this many blocks deep in the main chain
+     */
+    int GetDepthInMainChain(interfaces::Chain::Lock& locked_chain) const;
+    bool IsInMainChain(interfaces::Chain::Lock& locked_chain) const { return GetDepthInMainChain(locked_chain) > 0; }
+
+    /**
+     * @return number of blocks to maturity for this transaction:
+     *  0 : is not a coinbase transaction, or is a mature coinbase transaction
+     * >0 : is a coinbase transaction which matures in this many blocks
+     */
+    int GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const;
+    bool hashUnset() const { return (hashBlock.IsNull() || hashBlock == ABANDON_HASH); }
+    bool isAbandoned() const { return (hashBlock == ABANDON_HASH); }
+    void setAbandoned() { hashBlock = ABANDON_HASH; }
+
+    const uint256& GetHash() const { return tx->GetHash(); }
+    bool IsCoinBase() const { return tx->IsCoinBase(); }
+    bool IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const;
 };
 
 class COutput