fix: c++17 cases. fix: old compiler support by defining templaye type on backward class.

Author: IamLupo

include/fix_std_cxx_17.pri

@@ -4,12 +4,12 @@
 ## Reference: https://stackoverflow.com/questions/46610996/cant-use-c17-features-using-g-7-2-in-qtcreator
 
 
-lessThan($$QT_MAJOR_VERSION, 5)
+lessThan(QT_MAJOR_VERSION, 5)
 {
 	QMAKE_CXXFLAGS += -std=c++17
 }
 
-isEqual($$QT_MINOR_VERSION, 5) | lessThan($$QT_MINOR_VERSION, 12)
+isEqual(QT_MINOR_VERSION, 5) : lessThan(QT_MINOR_VERSION, 12)
 {
 	QMAKE_CXXFLAGS += -std=c++17
 }

src/cblock.cpp

@@ -726,7 +726,7 @@ bool CBlock::SetBestChain(CTxDB& txdb, CBlockIndex* pindexNew)
 		}
 
 		// Connect further blocks
-		for(CBlockIndex *pindex : backwards(vpindexSecondary))
+		for(CBlockIndex *pindex : backwards<std::vector<CBlockIndex*>>(vpindexSecondary))
 		{
 			CBlock block;
 			if (!block.ReadFromDisk(pindex))

src/checkpoints.cpp

@@ -73,7 +73,7 @@ namespace Checkpoints
     {
 		MapCheckpoints& checkpoints = (TestNet() ? mapCheckpointsTestnet : mapCheckpoints);
 
-		for(const MapCheckpoints::value_type& i : backwards(checkpoints))
+		for(const MapCheckpoints::value_type& i : backwards<MapCheckpoints>(checkpoints))
 		{
 			const uint256& hash = i.second;
 			std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);

src/cmasternodepayments.cpp

@@ -263,7 +263,7 @@ bool CMasternodePayments::ProcessBlock(int nBlockHeight)
 
 	std::vector<CTxIn> vecLastPayments;
 
-	for(CMasternodePaymentWinner& winner : backwards(vWinning))
+	for(CMasternodePaymentWinner& winner : backwards<std::vector<CMasternodePaymentWinner>>(vWinning))
 	{
 		//if we already have the same vin - we have one full payment cycle, break
 		if(vecLastPayments.size() > (unsigned int)nMinimumAge)
@@ -301,7 +301,7 @@ bool CMasternodePayments::ProcessBlock(int nBlockHeight)
 	{
 		LogPrintf(" Find by reverse \n");
 
-		for(CTxIn& vinLP : backwards(vecLastPayments))
+		for(CTxIn& vinLP : backwards<std::vector<CTxIn>>(vecLastPayments))
 		{
 			CMasternode* pmn = mnodeman.Find(vinLP);
 			if(pmn != NULL)

src/instantx.cpp

@@ -295,7 +295,7 @@ int64_t CreateNewLock(CTransaction tx)
 {
 	int64_t nTxAge = 0;
 
-	for(CTxIn i : backwards(tx.vin))
+	for(CTxIn i : backwards<std::vector<CTxIn>>(tx.vin))
 	{
 		nTxAge = GetInputAge(i);
 

src/main.cpp

@@ -1744,7 +1744,7 @@ bool Reorganize(CTxDB& txdb, CBlockIndex* pindexNew)
 		// Queue memory transactions to resurrect.
 		// We only do this for blocks after the last checkpoint (reorganisation before that
 		// point should only happen with -reindex/-loadblock, or a misbehaving peer.
-		for(const CTransaction& tx : backwards(block.vtx))
+		for(const CTransaction& tx : backwards<std::vector<CTransaction>>(block.vtx))
 		{
 			if (!(tx.IsCoinBase() || tx.IsCoinStake()) && pindex->nHeight > Checkpoints::GetTotalBlocksEstimate())
 			{