Add CMerkleTx::IsImmatureCoinBase method

All but one call to GetBlocksToMaturity is testing it relative to 0
for the purposes of determining whether the coinbase tx is immature.
In such case, the value greater than 0 implies that the tx is coinbase,
so there is no need to separately test that status.

This names the concept for easy singular use.

src/wallet/rpcwallet.cpp

@@ -1851,7 +1851,7 @@ static void ListTransactions(CWallet* const pwallet, const CWalletTx& wtx, const
                 {
                     if (wtx.GetDepthInMainChain() < 1)
                         entry.pushKV("category", "orphan");
-                    else if (wtx.GetBlocksToMaturity() > 0)
+                    else if (wtx.IsImmatureCoinBase())
                         entry.pushKV("category", "immature");
                     else
                         entry.pushKV("category", "generate");
@@ -2147,7 +2147,7 @@ static UniValue listaccounts(const JSONRPCRequest& request)
         std::list<COutputEntry> listReceived;
         std::list<COutputEntry> listSent;
         int nDepth = wtx.GetDepthInMainChain();
-        if (wtx.GetBlocksToMaturity() > 0 || nDepth < 0)
+        if (wtx.IsImmatureCoinBase() || nDepth < 0)
             continue;
         wtx.GetAmounts(listReceived, listSent, nFee, strSentAccount, includeWatchonly);
         mapAccountBalances[strSentAccount] -= nFee;

src/wallet/wallet.cpp

@@ -1894,7 +1894,7 @@ CAmount CWalletTx::GetDebit(const isminefilter& filter) const
 CAmount CWalletTx::GetCredit(const isminefilter& filter) const
 {
     // Must wait until coinbase is safely deep enough in the chain before valuing it
-    if (IsCoinBase() && GetBlocksToMaturity() > 0)
+    if (IsImmatureCoinBase())
         return 0;
 
     CAmount credit = 0;
@@ -1926,8 +1926,7 @@ CAmount CWalletTx::GetCredit(const isminefilter& filter) const
 
 CAmount CWalletTx::GetImmatureCredit(bool fUseCache) const
 {
-    if (IsCoinBase() && GetBlocksToMaturity() > 0 && IsInMainChain())
+    if (IsImmatureCoinBase() && IsInMainChain()) {
-    {
         if (fUseCache && fImmatureCreditCached)
             return nImmatureCreditCached;
         nImmatureCreditCached = pwallet->GetCredit(*tx, ISMINE_SPENDABLE);
@@ -1944,7 +1943,7 @@ CAmount CWalletTx::GetAvailableCredit(bool fUseCache, const isminefilter& filter
         return 0;
 
     // Must wait until coinbase is safely deep enough in the chain before valuing it
-    if (IsCoinBase() && GetBlocksToMaturity() > 0)
+    if (IsImmatureCoinBase())
         return 0;
 
     CAmount* cache = nullptr;
@@ -1985,8 +1984,7 @@ CAmount CWalletTx::GetAvailableCredit(bool fUseCache, const isminefilter& filter
 
 CAmount CWalletTx::GetImmatureWatchOnlyCredit(const bool fUseCache) const
 {
-    if (IsCoinBase() && GetBlocksToMaturity() > 0 && IsInMainChain())
+    if (IsImmatureCoinBase() && IsInMainChain()) {
-    {
         if (fUseCache && fImmatureWatchCreditCached)
             return nImmatureWatchCreditCached;
         nImmatureWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
@@ -2199,7 +2197,7 @@ CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth, cons
     for (const auto& entry : mapWallet) {
         const CWalletTx& wtx = entry.second;
         const int depth = wtx.GetDepthInMainChain();
-        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.GetBlocksToMaturity() > 0) {
+        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.IsImmatureCoinBase()) {
             continue;
         }
 
@@ -2259,7 +2257,7 @@ void CWallet::AvailableCoins(std::vector<COutput> &vCoins, bool fOnlySafe, const
         if (!CheckFinalTx(*pcoin->tx))
             continue;
 
-        if (pcoin->IsCoinBase() && pcoin->GetBlocksToMaturity() > 0)
+        if (pcoin->IsImmatureCoinBase())
             continue;
 
         int nDepth = pcoin->GetDepthInMainChain();
@@ -3521,7 +3519,7 @@ std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()
             if (!pcoin->IsTrusted())
                 continue;
 
-            if (pcoin->IsCoinBase() && pcoin->GetBlocksToMaturity() > 0)
+            if (pcoin->IsImmatureCoinBase())
                 continue;
 
             int nDepth = pcoin->GetDepthInMainChain();
@@ -4397,6 +4395,11 @@ int CMerkleTx::GetBlocksToMaturity() const
     return std::max(0, (COINBASE_MATURITY+1) - GetDepthInMainChain());
 }
 
+bool CMerkleTx::IsImmatureCoinBase() const
+{
+    // note GetBlocksToMaturity is 0 for non-coinbase tx
+    return GetBlocksToMaturity() > 0;
+}
 
 bool CWalletTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState& state)
 {

src/wallet/wallet.h

@@ -266,6 +266,12 @@ public:
      */
     int GetDepthInMainChain() const;
     bool IsInMainChain() const { return GetDepthInMainChain() > 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() const;
     bool hashUnset() const { return (hashBlock.IsNull() || hashBlock == ABANDON_HASH); }
     bool isAbandoned() const { return (hashBlock == ABANDON_HASH); }
@@ -273,6 +279,7 @@ public:
 
     const uint256& GetHash() const { return tx->GetHash(); }
     bool IsCoinBase() const { return tx->IsCoinBase(); }
+    bool IsImmatureCoinBase() const;
 };
 
 //Get the marginal bytes of spending the specified output