miner: adjust clock to timewarp rule

src/consensus/consensus.h

@@ -27,4 +27,11 @@ static const size_t MIN_SERIALIZABLE_TRANSACTION_WEIGHT = WITNESS_SCALE_FACTOR *
 /** Interpret sequence numbers as relative lock-time constraints. */
 static constexpr unsigned int LOCKTIME_VERIFY_SEQUENCE = (1 << 0);
 
+/**
+ * Maximum number of seconds that the timestamp of the first
+ * block of a difficulty adjustment period is allowed to
+ * be earlier than the last block of the previous period (BIP94).
+ */
+static constexpr int64_t MAX_TIMEWARP = 600;
+
 #endif // BITCOIN_CONSENSUS_CONSENSUS_H

src/node/miner.cpp

@@ -33,6 +33,14 @@ int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParam
     int64_t nOldTime = pblock->nTime;
     int64_t nNewTime{std::max<int64_t>(pindexPrev->GetMedianTimePast() + 1, TicksSinceEpoch<std::chrono::seconds>(NodeClock::now()))};
 
+    if (consensusParams.enforce_BIP94) {
+        // Height of block to be mined.
+        const int height{pindexPrev->nHeight + 1};
+        if (height % consensusParams.DifficultyAdjustmentInterval() == 0) {
+            nNewTime = std::max<int64_t>(nNewTime, pindexPrev->GetBlockTime() - MAX_TIMEWARP);
+        }
+    }
+
     if (nOldTime < nNewTime) {
         pblock->nTime = nNewTime;
     }

src/validation.cpp

@@ -107,13 +107,6 @@ const std::vector<std::string> CHECKLEVEL_DOC {
  * */
 static constexpr int PRUNE_LOCK_BUFFER{10};
 
-/**
- * Maximum number of seconds that the timestamp of the first
- * block of a difficulty adjustment period is allowed to
- * be earlier than the last block of the previous period (BIP94).
- */
-static constexpr int64_t MAX_TIMEWARP = 600;
-
 GlobalMutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
 uint256 g_best_block;