refactor: Pass const reference instead of pointer to GetBlockScriptFlags

The function dereferences the pointer and can not accept nullptr. Change
the arg to a const reference to clarify this for the caller.

src/validation.cpp

@@ -302,7 +302,7 @@ bool CheckSequenceLocks(CBlockIndex* tip,
 }
 
 // Returns the script flags which should be checked for a given block
-static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& chainparams);
+static unsigned int GetBlockScriptFlags(const CBlockIndex& block_index, const Consensus::Params& chainparams);
 
 static void LimitMempoolSize(CTxMemPool& pool, CCoinsViewCache& coins_cache, size_t limit, std::chrono::seconds age)
     EXCLUSIVE_LOCKS_REQUIRED(pool.cs, ::cs_main)
@@ -939,7 +939,7 @@ bool MemPoolAccept::ConsensusScriptChecks(const ATMPArgs& args, Workspace& ws)
     // There is a similar check in CreateNewBlock() to prevent creating
     // invalid blocks (using TestBlockValidity), however allowing such
     // transactions into the mempool can be exploited as a DoS attack.
-    unsigned int currentBlockScriptVerifyFlags = GetBlockScriptFlags(m_active_chainstate.m_chain.Tip(), chainparams.GetConsensus());
+    unsigned int currentBlockScriptVerifyFlags{GetBlockScriptFlags(*m_active_chainstate.m_chain.Tip(), chainparams.GetConsensus())};
     if (!CheckInputsFromMempoolAndCache(tx, state, m_view, m_pool, currentBlockScriptVerifyFlags,
                                         ws.m_precomputed_txdata, m_active_chainstate.CoinsTip())) {
         LogPrintf("BUG! PLEASE REPORT THIS! CheckInputScripts failed against latest-block but not STANDARD flags %s, %s\n", hash.ToString(), state.ToString());
@@ -1579,7 +1579,7 @@ public:
 
 static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS] GUARDED_BY(cs_main);
 
-static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& consensusparams)
+static unsigned int GetBlockScriptFlags(const CBlockIndex& block_index, const Consensus::Params& consensusparams)
 {
     unsigned int flags = SCRIPT_VERIFY_NONE;
 
@@ -1589,35 +1589,35 @@ static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consens
     // mainnet and testnet), so for simplicity, always leave P2SH
     // on except for the one violating block.
     if (consensusparams.BIP16Exception.IsNull() || // no bip16 exception on this chain
-        pindex->phashBlock == nullptr || // this is a new candidate block, eg from TestBlockValidity()
-        *pindex->phashBlock != consensusparams.BIP16Exception) // this block isn't the historical exception
+        block_index.phashBlock == nullptr || // this is a new candidate block, eg from TestBlockValidity()
+        *block_index.phashBlock != consensusparams.BIP16Exception) // this block isn't the historical exception
     {
         // Enforce WITNESS rules whenever P2SH is in effect
         flags |= SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS;
     }
 
     // Enforce the DERSIG (BIP66) rule
-    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_DERSIG)) {
+    if (DeploymentActiveAt(block_index, consensusparams, Consensus::DEPLOYMENT_DERSIG)) {
         flags |= SCRIPT_VERIFY_DERSIG;
     }
 
     // Enforce CHECKLOCKTIMEVERIFY (BIP65)
-    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_CLTV)) {
+    if (DeploymentActiveAt(block_index, consensusparams, Consensus::DEPLOYMENT_CLTV)) {
         flags |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
     }
 
     // Enforce CHECKSEQUENCEVERIFY (BIP112)
-    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_CSV)) {
+    if (DeploymentActiveAt(block_index, consensusparams, Consensus::DEPLOYMENT_CSV)) {
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
     // Enforce Taproot (BIP340-BIP342)
-    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_TAPROOT)) {
+    if (DeploymentActiveAt(block_index, consensusparams, Consensus::DEPLOYMENT_TAPROOT)) {
         flags |= SCRIPT_VERIFY_TAPROOT;
     }
 
     // Enforce BIP147 NULLDUMMY (activated simultaneously with segwit)
-    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_SEGWIT)) {
+    if (DeploymentActiveAt(block_index, consensusparams, Consensus::DEPLOYMENT_SEGWIT)) {
         flags |= SCRIPT_VERIFY_NULLDUMMY;
     }
 
@@ -1625,7 +1625,6 @@ static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consens
 }
 
 
-
 static int64_t nTimeCheck = 0;
 static int64_t nTimeForks = 0;
 static int64_t nTimeVerify = 0;
@@ -1811,7 +1810,7 @@ bool CChainState::ConnectBlock(const CBlock& block, BlockValidationState& state,
     }
 
     // Get the script flags for this block
-    unsigned int flags = GetBlockScriptFlags(pindex, m_params.GetConsensus());
+    unsigned int flags{GetBlockScriptFlags(*pindex, m_params.GetConsensus())};
 
     int64_t nTime2 = GetTimeMicros(); nTimeForks += nTime2 - nTime1;
     LogPrint(BCLog::BENCH, "    - Fork checks: %.2fms [%.2fs (%.2fms/blk)]\n", MILLI * (nTime2 - nTime1), nTimeForks * MICRO, nTimeForks * MILLI / nBlocksTotal);