[validation] Remove unused cacheSigStore from CheckInputsFromMempoolAndCache

CheckInputsFromMempoolAndCache() is only called in one place, and
cacheSigStore is set to true in that call site. Remove the argument
entirely.

Also improve commenting.

Author: jnewbery

src/validation.cpp

@@ -392,7 +392,7 @@ static void UpdateMempoolForReorg(DisconnectedBlockTransactions& disconnectpool,
 // Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
 // were somehow broken and returning the wrong scriptPubKeys
 static bool CheckInputsFromMempoolAndCache(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& view, const CTxMemPool& pool,
-                 unsigned int flags, bool cacheSigStore, PrecomputedTransactionData& txdata) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
+                 unsigned int flags, PrecomputedTransactionData& txdata) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
 
     // pool.cs should be locked already, but go ahead and re-take the lock here
@@ -422,7 +422,8 @@ static bool CheckInputsFromMempoolAndCache(const CTransaction& tx, CValidationSt
         }
     }
 
-    return CheckInputs(tx, state, view, flags, cacheSigStore, true, txdata);
+    // Call CheckInputs() to cache signature and script validity against current tip consensus rules.
+    return CheckInputs(tx, state, view, flags, /* cacheSigStore = */ true, /* cacheFullSciptStore = */ true, txdata);
 }
 
 namespace {
@@ -959,7 +960,7 @@ bool MemPoolAccept::ConsensusScriptChecks(ATMPArgs& args, Workspace& ws, Precomp
     // invalid blocks (using TestBlockValidity), however allowing such
     // transactions into the mempool can be exploited as a DoS attack.
     unsigned int currentBlockScriptVerifyFlags = GetBlockScriptFlags(::ChainActive().Tip(), chainparams.GetConsensus());
-    if (!CheckInputsFromMempoolAndCache(tx, state, m_view, m_pool, currentBlockScriptVerifyFlags, true, txdata)) {
+    if (!CheckInputsFromMempoolAndCache(tx, state, m_view, m_pool, currentBlockScriptVerifyFlags, txdata)) {
         return error("%s: BUG! PLEASE REPORT THIS! CheckInputs failed against latest-block but not STANDARD flags %s, %s",
                 __func__, hash.ToString(), FormatStateMessage(state));
     }