3 files changed, 48 insertions, 7 deletions
diff --git a/src/consensus/params.h b/src/consensus/params.h
index 28c95e0884..9205cfee87 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -11,13 +11,27 @@
 
 namespace Consensus {
 
-enum DeploymentPos
-{
+/**
+ * A buried deployment is one where the height of the activation has been hardcoded into
+ * the client implementation long after the consensus change has activated. See BIP 90.
+ */
+enum BuriedDeployment : int16_t {
+    // buried deployments get negative values to avoid overlap with DeploymentPos
+    DEPLOYMENT_HEIGHTINCB = std::numeric_limits<int16_t>::min(),
+    DEPLOYMENT_CLTV,
+    DEPLOYMENT_DERSIG,
+    DEPLOYMENT_CSV,
+    DEPLOYMENT_SEGWIT,
+};
+constexpr bool ValidDeployment(BuriedDeployment dep) { return DEPLOYMENT_HEIGHTINCB <= dep && dep <= DEPLOYMENT_SEGWIT; }
+
+enum DeploymentPos : uint16_t {
     DEPLOYMENT_TESTDUMMY,
     DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
-    // NOTE: Also add new deployments to VersionBitsDeploymentInfo in versionbits.cpp
+    // NOTE: Also add new deployments to VersionBitsDeploymentInfo in deploymentinfo.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };
+constexpr bool ValidDeployment(DeploymentPos dep) { return DEPLOYMENT_TESTDUMMY <= dep && dep <= DEPLOYMENT_TAPROOT; }
 
 /**
  * Struct for each individual consensus rule change using BIP9.
@@ -100,7 +114,25 @@ struct Params {
      */
     bool signet_blocks{false};
     std::vector<uint8_t> signet_challenge;
+
+    int DeploymentHeight(BuriedDeployment dep) const
+    {
+        switch (dep) {
+        case DEPLOYMENT_HEIGHTINCB:
+            return BIP34Height;
+        case DEPLOYMENT_CLTV:
+            return BIP65Height;
+        case DEPLOYMENT_DERSIG:
+            return BIP66Height;
+        case DEPLOYMENT_CSV:
+            return CSVHeight;
+        case DEPLOYMENT_SEGWIT:
+            return SegwitHeight;
+        } // no default case, so the compiler can warn about missing cases
+        return std::numeric_limits<int>::max();
+    }
 };
+
 } // namespace Consensus
 
 #endif // BITCOIN_CONSENSUS_PARAMS_H
diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp
index f595f16eab..0ab790ccdc 100644
--- a/src/consensus/tx_verify.cpp
+++ b/src/consensus/tx_verify.cpp
@@ -20,6 +20,15 @@ bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
         return true;
     if ((int64_t)tx.nLockTime < ((int64_t)tx.nLockTime < LOCKTIME_THRESHOLD ? (int64_t)nBlockHeight : nBlockTime))
         return true;
+
+    // Even if tx.nLockTime isn't satisfied by nBlockHeight/nBlockTime, a
+    // transaction is still considered final if all inputs' nSequence ==
+    // SEQUENCE_FINAL (0xffffffff), in which case nLockTime is ignored.
+    //
+    // Because of this behavior OP_CHECKLOCKTIMEVERIFY/CheckLockTime() will
+    // also check that the spending input's nSequence != SEQUENCE_FINAL,
+    // ensuring that an unsatisfied nLockTime value will actually cause
+    // IsFinalTx() to return false here:
     for (const auto& txin : tx.vin) {
         if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL))
             return false;
@@ -135,7 +144,7 @@ unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& in
     return nSigOps;
 }
 
-int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags)
+int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, uint32_t flags)
 {
     int64_t nSigOps = GetLegacySigOpCount(tx) * WITNESS_SCALE_FACTOR;
 
diff --git a/src/consensus/tx_verify.h b/src/consensus/tx_verify.h
index e78dc9f2a5..264433c33d 100644
--- a/src/consensus/tx_verify.h
+++ b/src/consensus/tx_verify.h
@@ -24,7 +24,7 @@ namespace Consensus {
  * @param[out] txfee Set to the transaction fee if successful.
  * Preconditions: tx.IsCoinBase() is false.
  */
-bool CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee);
+[[nodiscard]] bool CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee);
 } // namespace Consensus
 
 /** Auxiliary functions for transaction validation (ideally should not be exposed) */
@@ -49,10 +49,10 @@ unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& ma
  * Compute total signature operation cost of a transaction.
  * @param[in] tx     Transaction for which we are computing the cost
  * @param[in] inputs Map of previous transactions that have outputs we're spending
- * @param[out] flags Script verification flags
+ * @param[in] flags Script verification flags
  * @return Total signature operation cost of tx
  */
-int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags);
+int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, uint32_t flags);
 
 /**
  * Check if transaction is final and can be included in a block with the