migration: Fix baseFee calculation (#240)

Change base fee calculation for transition block

Previously we used the parent base fee, now we use the eip1559
calculation to calculate the base fee for the transition block.

Also updated the referenced op-geth that includes an updated
CalcBaseFee function.

The approach was changed to remove reliance on IsCel2 inside CalcBaseFee
which helps to avoid unexpected consequences when working with tests that
do or don't set the cel2 fork

Co-authored-by: Piers Powlesland <[email protected]>

op-chain-ops/cmd/celo-migrate/state.go

@@ -13,6 +13,7 @@ import (
 	"github.com/ethereum-optimism/optimism/op-service/jsonutil"
 	"github.com/ethereum-optimism/optimism/op-service/predeploys"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
 	"github.com/ethereum/go-ethereum/contracts/addresses"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -146,29 +147,62 @@ func applyStateMigrationChanges(config *genesis.DeployConfig, l2Allocs types.Gen
 		log.Warn("Error setting up distribution schedule", "error", err)
 	}
 
-	migrationBlock := new(big.Int).Add(header.Number, common.Big1)
+	migrationBlockNumber := new(big.Int).Add(header.Number, common.Big1)
 
 	// We're done messing around with the database, so we can now commit the changes to the DB.
 	// Note that this doesn't actually write the changes to disk.
 	log.Info("Committing state DB")
-	newRoot, err := db.Commit(migrationBlock.Uint64(), true)
+	newRoot, err := db.Commit(migrationBlockNumber.Uint64(), true)
 	if err != nil {
 		return nil, err
 	}
 
-	baseFee := new(big.Int).SetUint64(params.InitialBaseFee)
-	if header.BaseFee != nil {
-		baseFee = header.BaseFee
-	}
-
 	if migrationBlockTime == 0 {
 		migrationBlockTime = uint64(time.Now().Unix())
 	}
 
+	// Set the standard options.
+	cfg.LondonBlock = migrationBlockNumber
+	cfg.BerlinBlock = migrationBlockNumber
+	cfg.ArrowGlacierBlock = migrationBlockNumber
+	cfg.GrayGlacierBlock = migrationBlockNumber
+	cfg.MergeNetsplitBlock = migrationBlockNumber
+	cfg.TerminalTotalDifficulty = big.NewInt(0)
+	cfg.TerminalTotalDifficultyPassed = true
+	cfg.ShanghaiTime = &migrationBlockTime
+	cfg.CancunTime = &migrationBlockTime
+
+	// Set the Optimism options.
+	cfg.Optimism = &params.OptimismConfig{
+		EIP1559Denominator:       config.EIP1559Denominator,
+		EIP1559DenominatorCanyon: &config.EIP1559DenominatorCanyon,
+		EIP1559Elasticity:        config.EIP1559Elasticity,
+	}
+
+	// Set the Celo options.
+	cfg.Celo = &params.CeloConfig{
+		EIP1559BaseFeeFloor: config.EIP1559BaseFeeFloor,
+	}
+
+	// Set Optimism hardforks
+	cfg.BedrockBlock = migrationBlockNumber
+	cfg.RegolithTime = &migrationBlockTime
+	cfg.CanyonTime = &migrationBlockTime
+	cfg.EcotoneTime = &migrationBlockTime
+	cfg.FjordTime = &migrationBlockTime
+	cfg.GraniteTime = &migrationBlockTime
+	cfg.Cel2Time = &migrationBlockTime
+
+	// Calculate the base fee for the migration block.
+	baseFee := new(big.Int).SetUint64(params.InitialBaseFee)
+	if header.BaseFee != nil {
+		baseFee = eip1559.CalcBaseFee(cfg, header, migrationBlockTime)
+	}
+
 	// If gas limit was zero at the transition point use a default of 30M.
 	// Note that in op-geth we use gasLimit==0 to indicate a pre-gingerbread
 	// block and adjust encoding appropriately, so we must make sure that
-	// gasLimit is non-zero, bacause L2 blocks are all post gingerbread.
+	// gasLimit is non-zero, because L2 blocks are all post gingerbread.
 	gasLimit := header.GasLimit
 	if gasLimit == 0 {
 		gasLimit = 30e6
@@ -183,7 +217,7 @@ func applyStateMigrationChanges(config *genesis.DeployConfig, l2Allocs types.Gen
 		ReceiptHash: types.EmptyReceiptsHash,
 		Bloom:       types.Bloom{},
 		Difficulty:  new(big.Int).Set(common.Big0),
-		Number:      migrationBlock,
+		Number:      migrationBlockNumber,
 		GasLimit:    gasLimit,
 		GasUsed:     0,
 		Time:        migrationBlockTime,
@@ -236,38 +270,6 @@ func applyStateMigrationChanges(config *genesis.DeployConfig, l2Allocs types.Gen
 	// Mark the first CeL2 block as finalized
 	rawdb.WriteFinalizedBlockHash(ldb, cel2Block.Hash())
 
-	// Set the standard options.
-	cfg.LondonBlock = cel2Block.Number()
-	cfg.BerlinBlock = cel2Block.Number()
-	cfg.ArrowGlacierBlock = cel2Block.Number()
-	cfg.GrayGlacierBlock = cel2Block.Number()
-	cfg.MergeNetsplitBlock = cel2Block.Number()
-	cfg.TerminalTotalDifficulty = big.NewInt(0)
-	cfg.TerminalTotalDifficultyPassed = true
-	cfg.ShanghaiTime = &cel2Header.Time
-	cfg.CancunTime = &cel2Header.Time
-
-	// Set the Optimism options.
-	cfg.Optimism = &params.OptimismConfig{
-		EIP1559Denominator:       config.EIP1559Denominator,
-		EIP1559DenominatorCanyon: &config.EIP1559DenominatorCanyon,
-		EIP1559Elasticity:        config.EIP1559Elasticity,
-	}
-
-	// Set the Celo options.
-	cfg.Celo = &params.CeloConfig{
-		EIP1559BaseFeeFloor: config.EIP1559BaseFeeFloor,
-	}
-
-	// Set Optimism hardforks
-	cfg.BedrockBlock = cel2Block.Number()
-	cfg.RegolithTime = &cel2Header.Time
-	cfg.CanyonTime = &cel2Header.Time
-	cfg.EcotoneTime = &cel2Header.Time
-	cfg.FjordTime = &cel2Header.Time
-	cfg.GraniteTime = &cel2Header.Time
-	cfg.Cel2Time = &cel2Header.Time
-
 	// Write the chain config to disk.
 	rawdb.WriteChainConfig(ldb, genesisHash, cfg)
 	marshalledConfig, err := json.Marshal(cfg)