Activate Taproot/Tapscript on regtest (BIP 341, BIP 342)

Define a versionbits-based activation for the new consensus rules on regtest.
No activation or activation mechanism is defined for testnet or mainnet.

src/chainparams.cpp

@@ -86,6 +86,11 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 1199145601; // January 1, 2008
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = 1230767999; // December 31, 2008
 
+        // Deployment of Taproot (BIPs 340-342)
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].bit = 2;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nStartTime = 1199145601; // January 1, 2008
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nTimeout = 1230767999; // December 31, 2008
+
         // The best chain should have at least this much work.
         consensus.nMinimumChainWork = uint256S("0x00000000000000000000000000000000000000000e1ab5ec9348e9f4b8eb8154");
 
@@ -197,6 +202,11 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 1199145601; // January 1, 2008
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = 1230767999; // December 31, 2008
 
+        // Deployment of Taproot (BIPs 340-342)
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].bit = 2;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nStartTime = 1199145601; // January 1, 2008
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nTimeout = 1230767999; // December 31, 2008
+
         // The best chain should have at least this much work.
         consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000000001495c1d5a01e2af8a23");
 
@@ -380,6 +390,9 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].bit = 28;
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 0;
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].bit = 2;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nStartTime = Consensus::BIP9Deployment::ALWAYS_ACTIVE;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TAPROOT].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
 
         // The best chain should have at least this much work.
         consensus.nMinimumChainWork = uint256S("0x00");

src/consensus/params.h

@@ -14,6 +14,7 @@ namespace Consensus {
 enum DeploymentPos
 {
     DEPLOYMENT_TESTDUMMY,
+    DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
     // NOTE: Also add new deployments to VersionBitsDeploymentInfo in versionbits.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };

src/rpc/blockchain.cpp

@@ -1355,6 +1355,7 @@ RPCHelpMan getblockchaininfo()
     BuriedForkDescPushBack(softforks, "csv", consensusParams.CSVHeight);
     BuriedForkDescPushBack(softforks, "segwit", consensusParams.SegwitHeight);
     BIP9SoftForkDescPushBack(softforks, "testdummy", consensusParams, Consensus::DEPLOYMENT_TESTDUMMY);
+    BIP9SoftForkDescPushBack(softforks, "taproot", consensusParams, Consensus::DEPLOYMENT_TAPROOT);
     obj.pushKV("softforks",             softforks);
 
     obj.pushKV("warnings", GetWarnings(false).original);

src/validation.cpp

@@ -1920,6 +1920,11 @@ static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consens
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
+    // Start enforcing Taproot using versionbits logic.
+    if (VersionBitsState(pindex->pprev, consensusparams, Consensus::DEPLOYMENT_TAPROOT, versionbitscache) == ThresholdState::ACTIVE) {
+        flags |= SCRIPT_VERIFY_TAPROOT;
+    }
+
     // Start enforcing BIP147 NULLDUMMY (activated simultaneously with segwit)
     if (IsWitnessEnabled(pindex->pprev, consensusparams)) {
         flags |= SCRIPT_VERIFY_NULLDUMMY;

src/versionbitsinfo.cpp

@@ -11,4 +11,8 @@ const struct VBDeploymentInfo VersionBitsDeploymentInfo[Consensus::MAX_VERSION_B
         /*.name =*/ "testdummy",
         /*.gbt_force =*/ true,
     },
+    {
+        /*.name =*/ "taproot",
+        /*.gbt_force =*/ true,
+    },
 };

test/functional/rpc_blockchain.py

@@ -146,7 +146,19 @@ class BlockchainTest(BitcoinTestFramework):
                         'possible': True,
                     },
                 },
-                'active': False}
+                'active': False
+            },
+            'taproot': {
+                'type': 'bip9',
+                'bip9': {
+                    'status': 'active',
+                    'start_time': -1,
+                    'timeout': 9223372036854775807,
+                    'since': 0
+                },
+                'height': 0,
+                'active': True
+            }
         })
 
     def _test_getchaintxstats(self):