Merge pull request #6318 from ethereum-optimism/clabby/ctb/alphabet-brute-force

feat(ctb): Fuzz alphabet game resolution on full d=4 tree

packages/contracts-bedrock/.gas-snapshot

@@ -83,16 +83,17 @@ FaucetTest:test_nonAdmin_drip_fails() (gas: 262520)
 FaucetTest:test_receive_succeeds() (gas: 17401)
 FaucetTest:test_withdraw_nonAdmin_reverts() (gas: 13145)
 FaucetTest:test_withdraw_succeeds() (gas: 78359)
-FaultDisputeGame_ResolvesCorrectly_CorrectRoot1:test_resolvesCorrectly_succeeds() (gas: 498900)
-FaultDisputeGame_ResolvesCorrectly_CorrectRoot2:test_resolvesCorrectly_succeeds() (gas: 503381)
-FaultDisputeGame_ResolvesCorrectly_CorrectRoot3:test_resolvesCorrectly_succeeds() (gas: 502679)
-FaultDisputeGame_ResolvesCorrectly_CorrectRoot4:test_resolvesCorrectly_succeeds() (gas: 505608)
-FaultDisputeGame_ResolvesCorrectly_CorrectRoot5:test_resolvesCorrectly_succeeds() (gas: 504939)
-FaultDisputeGame_ResolvesCorrectly_IncorrectRoot1:test_resolvesCorrectly_succeeds() (gas: 497692)
-FaultDisputeGame_ResolvesCorrectly_IncorrectRoot2:test_resolvesCorrectly_succeeds() (gas: 502173)
-FaultDisputeGame_ResolvesCorrectly_IncorrectRoot3:test_resolvesCorrectly_succeeds() (gas: 501471)
-FaultDisputeGame_ResolvesCorrectly_IncorrectRoot4:test_resolvesCorrectly_succeeds() (gas: 502373)
-FaultDisputeGame_ResolvesCorrectly_IncorrectRoot5:test_resolvesCorrectly_succeeds() (gas: 501731)
+FaultDisputeGame_ResolvesCorrectly_Chaos:test_resolvesCorrectly_succeeds() (gas: 111450391)
+FaultDisputeGame_ResolvesCorrectly_CorrectRoot1:test_resolvesCorrectly_succeeds() (gas: 498867)
+FaultDisputeGame_ResolvesCorrectly_CorrectRoot2:test_resolvesCorrectly_succeeds() (gas: 505669)
+FaultDisputeGame_ResolvesCorrectly_CorrectRoot3:test_resolvesCorrectly_succeeds() (gas: 502410)
+FaultDisputeGame_ResolvesCorrectly_CorrectRoot4:test_resolvesCorrectly_succeeds() (gas: 505545)
+FaultDisputeGame_ResolvesCorrectly_CorrectRoot5:test_resolvesCorrectly_succeeds() (gas: 504906)
+FaultDisputeGame_ResolvesCorrectly_IncorrectRoot1:test_resolvesCorrectly_succeeds() (gas: 497632)
+FaultDisputeGame_ResolvesCorrectly_IncorrectRoot2:test_resolvesCorrectly_succeeds() (gas: 504434)
+FaultDisputeGame_ResolvesCorrectly_IncorrectRoot3:test_resolvesCorrectly_succeeds() (gas: 501175)
+FaultDisputeGame_ResolvesCorrectly_IncorrectRoot4:test_resolvesCorrectly_succeeds() (gas: 502310)
+FaultDisputeGame_ResolvesCorrectly_IncorrectRoot5:test_resolvesCorrectly_succeeds() (gas: 501671)
 FaultDisputeGame_Test:test_extraData_succeeds() (gas: 17426)
 FaultDisputeGame_Test:test_gameData_succeeds() (gas: 17917)
 FaultDisputeGame_Test:test_gameStart_succeeds() (gas: 10315)

packages/contracts-bedrock/contracts/dispute/FaultDisputeGame.sol

@@ -137,7 +137,7 @@ contract FaultDisputeGame is IFaultDisputeGame, Clone, Semver {
         //            branch because (n - n) % 2 == 0.
         bool validStep = VM.step(_stateData, _proof) == Claim.unwrap(postState.claim);
         bool parentPostAgree = (parentPos.depth() - postState.position.depth()) % 2 == 0;
-        if ((parentPostAgree && validStep) || (!parentPostAgree && !validStep)) revert ValidStep();
+        if (parentPostAgree == validStep) revert ValidStep();
 
         // Set the parent claim as countered. We do not need to append a new claim to the game;
         // instead, we can just set the existing parent as countered.