Merge bitcoin/bitcoin#23512: policy: Treat taproot as always active

fa3e0da06b491b8c0fa2dbae37682a9112c9deb8 policy: Treat taproot as always active (MarcoFalke)

Pull request description:

  Now that taproot is active, it can be treated as if it was always active for policy for the next major release. This simplifies the code and changes two things:

  * Importing `tr` descriptors can be done before the chain is fully synced. This is fine, because the wallet will already generate `tr` descriptors by default (regardless of the taproot status) after commit 47fe7445e7f54aee10ec6dbc53f1db1adbeb43de.
  * Valid taproot spends won't be rejected from the mempool before taproot is active. This is strictly speaking a bugfix after commit 47fe7445e7f54aee10ec6dbc53f1db1adbeb43de, since the wallet may generate taproot spends before the chain is fully synced. For example, a slow node or a purposefully offline node. Currently, the wallet needs the mempool to account for change. See https://github.com/bitcoin/bitcoin/issues/11887.

  A similar change was done for segwit v0 in https://github.com/bitcoin/bitcoin/pull/13120 .

  This effectively reverts commit c5ec0367d718544caa3a1578d6c730fc92ee4e94.

ACKs for top commit:
  mjdietzx:
    Code Review ACK fa3e0da06b491b8c0fa2dbae37682a9112c9deb8
  achow101:
    ACK fa3e0da06b491b8c0fa2dbae37682a9112c9deb8
  sipa:
    utACK fa3e0da06b491b8c0fa2dbae37682a9112c9deb8
  gruve-p:
    ACK https://github.com/bitcoin/bitcoin/pull/23512/commits/fa3e0da06b491b8c0fa2dbae37682a9112c9deb8
  gunar:
    Code Review + tACK fa3e0da06
  rajarshimaitra:
    code review + tACK https://github.com/bitcoin/bitcoin/pull/23512/commits/fa3e0da06b491b8c0fa2dbae37682a9112c9deb8

Tree-SHA512: c6dc7a4e6c345bdec33f256847dc63906ab1696aa683ab9b32a79e715613950884ac3a1a7a44e95f31bb28e58dd64679a616175f7e152b21f5550f3337c8e622

2 files changed, 5 insertions, 9 deletions

diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index fced397e51..2c30b20d5b 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -161,13 +161,13 @@ bool IsStandardTx(const CTransaction& tx, bool permit_bare_multisig, const CFeeR
  *
  * Note that only the non-witness portion of the transaction is checked here.
  */
-bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs, bool taproot_active)
+bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
 {
-    if (tx.IsCoinBase())
+    if (tx.IsCoinBase()) {
         return true; // Coinbases don't use vin normally
+    }
 
-    for (unsigned int i = 0; i < tx.vin.size(); i++)
-    {
+    for (unsigned int i = 0; i < tx.vin.size(); i++) {
         const CTxOut& prev = mapInputs.AccessCoin(tx.vin[i].prevout).out;
 
         std::vector<std::vector<unsigned char> > vSolutions;
@@ -189,9 +189,6 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs,
             if (subscript.GetSigOpCount(true) > MAX_P2SH_SIGOPS) {
                 return false;
             }
-        } else if (whichType == TxoutType::WITNESS_V1_TAPROOT) {
-            // Don't allow Taproot spends unless Taproot is active.
-            if (!taproot_active) return false;
         }
     }
 
diff --git a/src/policy/policy.h b/src/policy/policy.h
index f2a3f35546..f6ac6500f6 100644
--- a/src/policy/policy.h
+++ b/src/policy/policy.h
@@ -105,10 +105,9 @@ bool IsStandardTx(const CTransaction& tx, bool permit_bare_multisig, const CFeeR
 /**
 * Check for standard transaction types
 * @param[in] mapInputs       Map of previous transactions that have outputs we're spending
-* @param[in] taproot_active  Whether or taproot consensus rules are active (used to decide whether spends of them are permitted)
 * @return True if all inputs (scriptSigs) use only standard transaction forms
 */
-bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs, bool taproot_active);
+bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
 /**
 * Check if the transaction is over standard P2WSH resources limit:
 * 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements