Merge bitcoin/bitcoin#31318: Drop script_pub_key arg from createNewBlock

52fd1511a7 test: drop scriptPubKeyIn arg from CreateNewBlock (Sjors Provoost)
ff41b9e296 Drop script_pub_key arg from createNewBlock (Sjors Provoost)
7ab733ede4 rpc: rename coinbase_script to coinbase_output_script (Sjors Provoost)

Pull request description:

  Providing a script for the coinbase transaction is only done in test code and for (unoptimized) CPU solo mining.

  Production miners use the `getblocktemplate` RPC which omits the coinbase transaction entirely from its block template, leaving it to external (pool) software to construct it.

  This commit removes the `script_pub_key argument` from `createNewBlock()` in the Mining interface.

  A coinbase script can still be passed via `BlockCreateOptions` instead. Tests are modified to do so.

ACKs for top commit:
  ryanofsky:
    Code review ACK 52fd1511a7. No change since last review other than rebase
  TheCharlatan:
    Re-ACK 52fd1511a7
  vasild:
    ACK 52fd1511a7

Tree-SHA512: c4b3a53774d9a5dc90950e77f47a64dbb68f971baffbb9a0d8f59332ef8e52d0c039130c925bde73135b3d0e79e65d91d1df30dc4cff13f32d8a72e5c56669d8

src/node/interfaces.cpp

@@ -1004,11 +1004,11 @@ public:
         return TestBlockValidity(state, chainman().GetParams(), chainman().ActiveChainstate(), block, tip, /*fCheckPOW=*/false, check_merkle_root);
     }
 
-    std::unique_ptr<BlockTemplate> createNewBlock(const CScript& script_pub_key, const BlockCreateOptions& options) override
+    std::unique_ptr<BlockTemplate> createNewBlock(const BlockCreateOptions& options) override
     {
         BlockAssembler::Options assemble_options{options};
         ApplyArgsManOptions(*Assert(m_node.args), assemble_options);
-        return std::make_unique<BlockTemplateImpl>(BlockAssembler{chainman().ActiveChainstate(), context()->mempool.get(), assemble_options}.CreateNewBlock(script_pub_key), m_node);
+        return std::make_unique<BlockTemplateImpl>(BlockAssembler{chainman().ActiveChainstate(), context()->mempool.get(), assemble_options}.CreateNewBlock(), m_node);
     }
 
     NodeContext* context() override { return &m_node; }

src/node/miner.cpp

@@ -106,7 +106,7 @@ void BlockAssembler::resetBlock()
     nFees = 0;
 }
 
-std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
+std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock()
 {
     const auto time_start{SteadyClock::now()};
 
@@ -151,7 +151,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     coinbaseTx.vin.resize(1);
     coinbaseTx.vin[0].prevout.SetNull();
     coinbaseTx.vout.resize(1);
-    coinbaseTx.vout[0].scriptPubKey = scriptPubKeyIn;
+    coinbaseTx.vout[0].scriptPubKey = m_options.coinbase_output_script;
     coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
     coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
     pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx));

src/node/miner.h

@@ -169,8 +169,8 @@ public:
 
     explicit BlockAssembler(Chainstate& chainstate, const CTxMemPool* mempool, const Options& options);
 
-    /** Construct a new block template with coinbase to scriptPubKeyIn */
-    std::unique_ptr<CBlockTemplate> CreateNewBlock(const CScript& scriptPubKeyIn);
+    /** Construct a new block template */
+    std::unique_ptr<CBlockTemplate> CreateNewBlock();
 
     inline static std::optional<int64_t> m_last_block_num_txs{};
     inline static std::optional<int64_t> m_last_block_weight{};

src/node/types.h

@@ -3,8 +3,8 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 //! @file node/types.h is a home for public enum and struct type definitions
-//! that are used by internally by node code, but also used externally by wallet
-//! or GUI code.
+//! that are used by internally by node code, but also used externally by wallet,
+//! mining or GUI code.
 //!
 //! This file is intended to define only simple types that do not have external
 //! dependencies. More complicated types should be defined in dedicated header
@@ -14,6 +14,7 @@
 #define BITCOIN_NODE_TYPES_H
 
 #include <cstddef>
+#include <script/script.h>
 
 namespace node {
 enum class TransactionError {
@@ -43,6 +44,22 @@ struct BlockCreateOptions {
      * transaction outputs.
      */
     size_t coinbase_output_max_additional_sigops{400};
+    /**
+     * Script to put in the coinbase transaction. The default is an
+     * anyone-can-spend dummy.
+     *
+     * Should only be used for tests, when the default doesn't suffice.
+     *
+     * Note that higher level code like the getblocktemplate RPC may omit the
+     * coinbase transaction entirely. It's instead constructed by pool software
+     * using fields like coinbasevalue, coinbaseaux and default_witness_commitment.
+     * This software typically also controls the payout outputs, even for solo
+     * mining.
+     *
+     * The size and sigops are not checked against
+     * coinbase_max_additional_weight and coinbase_output_max_additional_sigops.
+     */
+    CScript coinbase_output_script{CScript() << OP_TRUE};
 };
 } // namespace node