Merge bitcoin#23630: Remove GetSpendHeight

fa3942f Remove GetSpendHeight (MarcoFalke)

Pull request description:

  It is unclear what the goal of the helper is, as the caller already
  knows the spend height before calling the helper.

  Also, in case the coins view is corrupted, LookupBlockIndex will return
  nullptr. Dereferencing a nullptr is UB.

  Fix both issues by removing it. Also, add a sanity check, which aborts
  if the coins view is corrupted.

ACKs for top commit:
  laanwj:
    Code review ACK fa3942f
  ryanofsky:
    Code review ACK fa3942f. I'm not aware of cases where coins GetBestBlock could be different from active chain tip, and asset seems sufficient to guarantee PR doesn't change behavior if that doesn't happen.

Tree-SHA512: 29f65d72e116ec5a4509e0947ceeaa5bb6b7dfd5d174d3c7945cb15fa266d590c4f8b48e6385de74ef7d7c84ebd2255de902ad9c87c24955348a91b12e5bffd5

Author: fanquake

src/validation.cpp

@@ -723,6 +723,8 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     // to coins_to_uncache)
     m_view.SetBackend(m_dummy);
 
+    assert(m_active_chainstate.m_blockman.LookupBlockIndex(m_view.GetBestBlock()) == m_active_chainstate.m_chain.Tip());
+
     // Only accept BIP68 sequence locked transactions that can be mined in the next
     // block; we don't want our mempool filled up with transactions that can't
     // be mined yet.
@@ -731,7 +733,8 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     if (!CheckSequenceLocks(m_active_chainstate.m_chain.Tip(), m_view, tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp))
         return state.Invalid(TxValidationResult::TX_PREMATURE_SPEND, "non-BIP68-final");
 
-    if (!Consensus::CheckTxInputs(tx, state, m_view, m_active_chainstate.m_blockman.GetSpendHeight(m_view), ws.m_base_fees)) {
+    // The mempool holds txs for the next block, so pass height+1 to CheckTxInputs
+    if (!Consensus::CheckTxInputs(tx, state, m_view, m_active_chainstate.m_chain.Height() + 1, ws.m_base_fees)) {
         return false; // state filled in by CheckTxInputs
     }
 
@@ -1311,14 +1314,6 @@ bool CScriptCheck::operator()() {
     return VerifyScript(scriptSig, m_tx_out.scriptPubKey, witness, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, m_tx_out.nValue, cacheStore, *txdata), &error);
 }
 
-int BlockManager::GetSpendHeight(const CCoinsViewCache& inputs)
-{
-    AssertLockHeld(cs_main);
-    CBlockIndex* pindexPrev = LookupBlockIndex(inputs.GetBestBlock());
-    return pindexPrev->nHeight + 1;
-}
-
-
 static CuckooCache::cache<uint256, SignatureCacheHasher> g_scriptExecutionCache;
 static CSHA256 g_scriptExecutionCacheHasher;
 

src/validation.h

@@ -478,13 +478,6 @@ class BlockManager
     //! Returns last CBlockIndex* that is a checkpoint
     CBlockIndex* GetLastCheckpoint(const CCheckpointData& data) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
-    /**
-     * Return the spend height, which is one more than the inputs.GetBestBlock().
-     * While checking, GetBestBlock() refers to the parent block. (protected by cs_main)
-     * This is also true for mempool checks.
-     */
-    int GetSpendHeight(const CCoinsViewCache& inputs) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
-
     ~BlockManager() {
         Unload();
     }