Mempool: Do not enforce TRUC checks on reorg

Not enforcing TRUC topology on reorg was the intended
behavior, but the appropriate bypass argument was not
checked.

This mistake means we could potentially invalidate a long
chain of perfectly incentive-compatible transactions that
were made historically, including subsequent non-TRUC
transactions, all of which may have been very high feerate.

Lastly, it wastes CPU cycles doing topology checks since
this behavior cannot actually enforce the topology in
general for the reorg setting.

Author: instagibbs

src/validation.cpp

@@ -1044,26 +1044,28 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     // Even though just checking direct mempool parents for inheritance would be sufficient, we
     // check using the full ancestor set here because it's more convenient to use what we have
     // already calculated.
-    if (const auto err{SingleTRUCChecks(ws.m_ptx, ws.m_ancestors, ws.m_conflicts, ws.m_vsize)}) {
-        // Single transaction contexts only.
-        if (args.m_allow_sibling_eviction && err->second != nullptr) {
-            // We should only be considering where replacement is considered valid as well.
-            Assume(args.m_allow_replacement);
-
-            // Potential sibling eviction. Add the sibling to our list of mempool conflicts to be
-            // included in RBF checks.
-            ws.m_conflicts.insert(err->second->GetHash());
-            // Adding the sibling to m_iters_conflicting here means that it doesn't count towards
-            // RBF Carve Out above. This is correct, since removing to-be-replaced transactions from
-            // the descendant count is done separately in SingleTRUCChecks for TRUC transactions.
-            ws.m_iters_conflicting.insert(m_pool.GetIter(err->second->GetHash()).value());
-            ws.m_sibling_eviction = true;
-            // The sibling will be treated as part of the to-be-replaced set in ReplacementChecks.
-            // Note that we are not checking whether it opts in to replaceability via BIP125 or TRUC
-            // (which is normally done in PreChecks). However, the only way a TRUC transaction can
-            // have a non-TRUC and non-BIP125 descendant is due to a reorg.
-        } else {
-            return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "TRUC-violation", err->first);
+    if (!args.m_bypass_limits) {
+        if (const auto err{SingleTRUCChecks(ws.m_ptx, ws.m_ancestors, ws.m_conflicts, ws.m_vsize)}) {
+            // Single transaction contexts only.
+            if (args.m_allow_sibling_eviction && err->second != nullptr) {
+                // We should only be considering where replacement is considered valid as well.
+                Assume(args.m_allow_replacement);
+
+                // Potential sibling eviction. Add the sibling to our list of mempool conflicts to be
+                // included in RBF checks.
+                ws.m_conflicts.insert(err->second->GetHash());
+                // Adding the sibling to m_iters_conflicting here means that it doesn't count towards
+                // RBF Carve Out above. This is correct, since removing to-be-replaced transactions from
+                // the descendant count is done separately in SingleTRUCChecks for TRUC transactions.
+                ws.m_iters_conflicting.insert(m_pool.GetIter(err->second->GetHash()).value());
+                ws.m_sibling_eviction = true;
+                // The sibling will be treated as part of the to-be-replaced set in ReplacementChecks.
+                // Note that we are not checking whether it opts in to replaceability via BIP125 or TRUC
+                // (which is normally done in PreChecks). However, the only way a TRUC transaction can
+                // have a non-TRUC and non-BIP125 descendant is due to a reorg.
+            } else {
+                return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "TRUC-violation", err->first);
+            }
         }
     }