scripted-diff: Avoid temporary copies when looping over std::map (Merge #13241)

The ::value_type of the std::map/std::multimap/std::unordered_map containers is
std::pair<const Key, T>. Dropping the const results in an unnecessary copy,
for example in C++11 range-based loops.

For this I started with a more general scripted diff, then narrowed it down
based on the inspection showing that all actual map/multimap/unordered_map
variables used in loops start with m or have map in the name.

-BEGIN VERIFY SCRIPT-
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : m/for (\1std::pair<const \2\3 : m/' src/*.cpp src/**/*.cpp
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : (.*)map/for (\1std::pair<const \2\3 : \4map/' src/*.cpp src/**/*.cpp
-END VERIFY SCRIPT-

Signed-off-by: pasta <pasta@dashboost.org>

src/init.cpp

@@ -757,7 +757,7 @@ void CleanupBlockRevFiles()
     // keeping a separate counter.  Once we hit a gap (or if 0 doesn't exist)
     // start removing block files.
     int nContigCounter = 0;
-    for (const std::pair<std::string, fs::path>& item : mapBlockFiles) {
+    for (const std::pair<const std::string, fs::path>& item : mapBlockFiles) {
         if (atoi(item.first) == nContigCounter) {
             nContigCounter++;
             continue;

src/qt/addresstablemodel.cpp

@@ -79,7 +79,7 @@ public:
         cachedAddressTable.clear();
         {
             LOCK(wallet->cs_wallet);
-            for (const std::pair<CTxDestination, CAddressBookData>& item : wallet->mapAddressBook)
+            for (const std::pair<const CTxDestination, CAddressBookData>& item : wallet->mapAddressBook)
             {
                 const CTxDestination& address = item.first;
                 bool fMine = IsMine(*wallet, address);

src/qt/coincontroldialog.cpp

@@ -667,7 +667,7 @@ void CoinControlDialog::updateView()
     std::map<QString, std::vector<COutput> > mapCoins;
     model->listCoins(mapCoins);
 
-    for (const std::pair<QString, std::vector<COutput>>& coins : mapCoins) {
+    for (const std::pair<const QString, std::vector<COutput>>& coins : mapCoins) {
         CCoinControlWidgetItem *itemWalletAddress = new CCoinControlWidgetItem();
         itemWalletAddress->setCheckState(COLUMN_CHECKBOX, Qt::Unchecked);
         QString sWalletAddress = coins.first;

src/rpc/net.cpp

@@ -501,7 +501,7 @@ UniValue getnetworkinfo(const JSONRPCRequest& request)
     UniValue localAddresses(UniValue::VARR);
     {
         LOCK(cs_mapLocalHost);
-        for (const std::pair<CNetAddr, LocalServiceInfo> &item : mapLocalHost)
+        for (const std::pair<const CNetAddr, LocalServiceInfo> &item : mapLocalHost)
         {
             UniValue rec(UniValue::VOBJ);
             rec.pushKV("address", item.first.ToString());

src/script/standard.cpp

@@ -72,7 +72,7 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::v
 
     // Scan templates
     const CScript& script1 = scriptPubKey;
-    for (const std::pair<txnouttype, CScript>& tplate : mTemplates)
+    for (const std::pair<const txnouttype, CScript>& tplate : mTemplates)
     {
         const CScript& script2 = tplate.second;
         vSolutionsRet.clear();

src/validation.cpp

@@ -4060,7 +4060,7 @@ bool CChainState::LoadBlockIndex(const Consensus::Params& consensus_params, CBlo
     // Calculate nChainWork
     std::vector<std::pair<int, CBlockIndex*> > vSortedByHeight;
     vSortedByHeight.reserve(mapBlockIndex.size());
-    for (const std::pair<uint256, CBlockIndex*>& item : mapBlockIndex)
+    for (const std::pair<const uint256, CBlockIndex*>& item : mapBlockIndex)
     {
         CBlockIndex* pindex = item.second;
         vSortedByHeight.push_back(std::make_pair(pindex->nHeight, pindex));
@@ -4132,7 +4132,7 @@ bool static LoadBlockIndexDB(const CChainParams& chainparams)
     // Check presence of blk files
     LogPrintf("Checking all blk files are present...\n");
     std::set<int> setBlkDataFiles;
-    for (const std::pair<uint256, CBlockIndex*>& item : mapBlockIndex)
+    for (const std::pair<const uint256, CBlockIndex*>& item : mapBlockIndex)
     {
         CBlockIndex* pindex = item.second;
         if (pindex->nStatus & BLOCK_HAVE_DATA) {

src/wallet/rpcwallet.cpp

@@ -118,7 +118,7 @@ void WalletTxToJSON(const CWalletTx& wtx, UniValue& entry)
     entry.pushKV("time", wtx.GetTxTime());
     entry.pushKV("timereceived", (int64_t)wtx.nTimeReceived);
 
-    for (const std::pair<std::string, std::string>& item : wtx.mapValue)
+    for (const std::pair<const std::string, std::string>& item : wtx.mapValue)
         entry.pushKV(item.first, item.second);
 }
 
@@ -371,7 +371,7 @@ UniValue getaddressesbyaccount(const JSONRPCRequest& request)
 
     // Find all addresses that have the given account
     UniValue ret(UniValue::VARR);
-    for (const std::pair<CTxDestination, CAddressBookData>& item : pwallet->mapAddressBook) {
+    for (const std::pair<const CTxDestination, CAddressBookData>& item : pwallet->mapAddressBook) {
         const CTxDestination& dest = item.first;
         const std::string& strName = item.second.name;
         if (strName == strAccount) {
@@ -732,7 +732,7 @@ UniValue getreceivedbyaddress(const JSONRPCRequest& request)
 
     // Tally
     CAmount nAmount = 0;
-    for (const std::pair<uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         const CWalletTx& wtx = pairWtx.second;
         if (wtx.IsCoinBase() || !CheckFinalTx(*wtx.tx))
             continue;
@@ -793,7 +793,7 @@ UniValue getreceivedbyaccount(const JSONRPCRequest& request)
 
     // Tally
     CAmount nAmount = 0;
-    for (const std::pair<uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         const CWalletTx& wtx = pairWtx.second;
         if (wtx.IsCoinBase() || !CheckFinalTx(*wtx.tx))
             continue;
@@ -1305,7 +1305,7 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
 
     // Tally
     std::map<CTxDestination, tallyitem> mapTally;
-    for (const std::pair<uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         const CWalletTx& wtx = pairWtx.second;
 
         if (wtx.IsCoinBase() || !CheckFinalTx(*wtx.tx))
@@ -1825,13 +1825,13 @@ UniValue listaccounts(const JSONRPCRequest& request)
             includeWatchonly = includeWatchonly | ISMINE_WATCH_ONLY;
 
     std::map<std::string, CAmount> mapAccountBalances;
-    for (const std::pair<CTxDestination, CAddressBookData>& entry : pwallet->mapAddressBook) {
+    for (const std::pair<const CTxDestination, CAddressBookData>& entry : pwallet->mapAddressBook) {
         if (IsMine(*pwallet, entry.first) & includeWatchonly) {  // This address belongs to me
             mapAccountBalances[entry.second.name] = 0;
         }
     }
 
-    for (const std::pair<uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         const CWalletTx& wtx = pairWtx.second;
         CAmount nFee;
         std::string strSentAccount;
@@ -1860,7 +1860,7 @@ UniValue listaccounts(const JSONRPCRequest& request)
         mapAccountBalances[entry.strAccount] += entry.nCreditDebit;
 
     UniValue ret(UniValue::VOBJ);
-    for (const std::pair<std::string, CAmount>& accountBalance : mapAccountBalances) {
+    for (const std::pair<const std::string, CAmount>& accountBalance : mapAccountBalances) {
         ret.pushKV(accountBalance.first, ValueFromAmount(accountBalance.second));
     }
     return ret;
@@ -1969,7 +1969,7 @@ UniValue listsinceblock(const JSONRPCRequest& request)
 
     UniValue transactions(UniValue::VARR);
 
-    for (const std::pair<uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx>& pairWtx : pwallet->mapWallet) {
         CWalletTx tx = pairWtx.second;
 
         if (depth == -1 || tx.GetDepthInMainChain() < depth) {

src/wallet/wallet.cpp

@@ -1477,7 +1477,7 @@ void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const
         // the previous block's coinbase, just in case it is ours, so
         // that we can notify the UI that it should now be displayed.
         if (pindex->pprev) {
-            for (const std::pair<uint256, CWalletTx>& p : mapWallet) {
+            for (const std::pair<const uint256, CWalletTx>& p : mapWallet) {
                 if (p.second.IsCoinBase() && p.second.hashBlock == pindex->pprev->GetBlockHash()) {
                     NotifyTransactionChanged(this, p.first, CT_UPDATED);
                     break;
@@ -4284,7 +4284,7 @@ bool CWallet::DelAddressBook(const CTxDestination& address)
 
         // Delete destdata tuples associated with address
         std::string strAddress = EncodeDestination(address);
-        for (const std::pair<std::string, std::string> &item : mapAddressBook[address].destdata)
+        for (const std::pair<const std::string, std::string> &item : mapAddressBook[address].destdata)
         {
             WalletBatch(*database).EraseDestData(strAddress, item.first);
         }
@@ -4693,7 +4693,7 @@ std::set<CTxDestination> CWallet::GetAccountAddresses(const std::string& strAcco
 {
     LOCK(cs_wallet);
     std::set<CTxDestination> result;
-    for (const std::pair<CTxDestination, CAddressBookData>& item : mapAddressBook)
+    for (const std::pair<const CTxDestination, CAddressBookData>& item : mapAddressBook)
     {
         const CTxDestination& address = item.first;
         const std::string& strName = item.second.name;