Merge #10558: Address nits from per-utxo change

21d4afa12 Comment clarifications in coins.cpp (Alex Morcos)
3c8a9aeff Add belt-and-suspenders in DisconnectBlock (Alex Morcos)

Tree-SHA512: d83e12ed71674faaaaebc03ffa1e2276984c35a29db419268ac9e14a45b33ccab716e3606dff8cfe1dcee4bec6e4794d2ca90341f10d5684be80e3fee61addf8

src/coins.h

@@ -306,6 +306,9 @@ private:
 void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight, bool check = false);
 
 //! Utility function to find any unspent output with a given txid.
+// This function can be quite expensive because in the event of a transaction
+// which is not found in the cache, it can cause up to MAX_OUTPUTS_PER_BLOCK
+// lookups to database, so it should be used with care.
 const Coin& AccessByTxid(const CCoinsViewCache& cache, const uint256& txid);
 
 #endif // BITCOIN_COINS_H

src/validation.cpp

@@ -1366,6 +1366,7 @@ static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex*
     for (int i = block.vtx.size() - 1; i >= 0; i--) {
         const CTransaction &tx = *(block.vtx[i]);
         uint256 hash = tx.GetHash();
+        bool is_coinbase = tx.IsCoinBase();
 
         // Check that all outputs are available and match the outputs in the block itself
         // exactly.
@@ -1374,7 +1375,7 @@ static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex*
                 COutPoint out(hash, o);
                 Coin coin;
                 bool is_spent = view.SpendCoin(out, &coin);
-                if (!is_spent || tx.vout[o] != coin.out) {
+                if (!is_spent || tx.vout[o] != coin.out || pindex->nHeight != coin.nHeight || is_coinbase != coin.fCoinBase) {
                     fClean = false; // transaction output mismatch
                 }
             }