Merge bitcoin/bitcoin#24732: Remove buggy and confusing IncrementExtraNonce

cccc4e879a8cb9d858a88ea46b28ea27ab79ca55 Remove nHeightEnd and nHeight in generateBlocks helper (MarcoFalke)
fa38b1c8bd29e2c792737f6481ab928e46396b7e Remove buggy and confusing IncrementExtraNonce (MarcoFalke)

Pull request description:

  IncrementExtraNonce has many issues:

  * It is test-only code, but part of bitcoind
  * It is using the block height of the tip, as opposed to the block's previous block as reference for the new height. See https://github.com/bitcoin/bitcoin/issues/24730#issuecomment-1085586193
  * It has no use case in regtest testing. With a low difficulty the extra nonce won't be incremented. With a high difficulty the test-only functions are clumsy to handle anyway. For example, the generate* RPCs will return an empty array once they reached `maxtries`, as opposed to an error. Also the calls can't be aborted early unless the node shuts down completely. So I think it is fine to just remove the extra nonce functionality and leave it to the outside to implement, if needed. For example, a wrapper script can call the `generate*` RPCs once every second, to use the timestamp as extra nonce.

ACKs for top commit:
  ajtowns:
    ACK cccc4e879a8cb9d858a88ea46b28ea27ab79ca55

Tree-SHA512: d8a3989ad280ebd4b1b574159b3a396b8a42134347e6be3c88445162d86624d221c416456f45ae75aea62ed8c8a1a9bb3a2532924abca2ef7a879cb8e6b15654

2 files changed, 0 insertions, 20 deletions

diff --git a/src/node/miner.cpp b/src/node/miner.cpp
index 917df91933..be5d58527b 100644
--- a/src/node/miner.cpp
+++ b/src/node/miner.cpp
@@ -430,22 +430,4 @@ void BlockAssembler::addPackageTxs(int& nPackagesSelected, int& nDescendantsUpda
         nDescendantsUpdated += UpdatePackagesForAdded(ancestors, mapModifiedTx);
     }
 }
-
-void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
-{
-    // Update nExtraNonce
-    static uint256 hashPrevBlock;
-    if (hashPrevBlock != pblock->hashPrevBlock) {
-        nExtraNonce = 0;
-        hashPrevBlock = pblock->hashPrevBlock;
-    }
-    ++nExtraNonce;
-    unsigned int nHeight = pindexPrev->nHeight + 1; // Height first in coinbase required for block.version=2
-    CMutableTransaction txCoinbase(*pblock->vtx[0]);
-    txCoinbase.vin[0].scriptSig = (CScript() << nHeight << CScriptNum(nExtraNonce));
-    assert(txCoinbase.vin[0].scriptSig.size() <= 100);
-
-    pblock->vtx[0] = MakeTransactionRef(std::move(txCoinbase));
-    pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
-}
 } // namespace node
diff --git a/src/node/miner.h b/src/node/miner.h
index 5fd9abc280..c8093ec883 100644
--- a/src/node/miner.h
+++ b/src/node/miner.h
@@ -200,8 +200,6 @@ private:
     int UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded, indexed_modified_transaction_set& mapModifiedTx) EXCLUSIVE_LOCKS_REQUIRED(m_mempool.cs);
 };
 
-/** Modify the extranonce in a block */
-void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned int& nExtraNonce);
 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev);
 
 /** Update an old GenerateCoinbaseCommitment from CreateNewBlock after the block txs have changed */