Add override.terminaltotaldifficulty flag (#4018)

* cmd/utils: initialize f.Value before setting variable

* override.terminaltotaldifficulty flag

* Add OverrideTerminalTotalDifficulty to default_flags

cmd/utils/customflags.go

@@ -154,11 +154,11 @@ func (b *bigValue) String() string {
 }
 
 func (b *bigValue) Set(s string) error {
-	int, ok := math.ParseBig256(s)
+	intVal, ok := math.ParseBig256(s)
 	if !ok {
 		return errors.New("invalid integer syntax")
 	}
-	*b = bigValue(*int)
+	*b = bigValue(*intVal)
 	return nil
 }
 
@@ -172,6 +172,7 @@ func (f BigFlag) String() string {
 
 func (f BigFlag) Apply(set *flag.FlagSet) {
 	eachName(f.Name, func(name string) {
+		f.Value = new(big.Int)
 		set.Var((*bigValue)(f.Value), f.Name, f.Usage)
 	})
 }

cmd/utils/flags.go

@@ -134,6 +134,10 @@ var (
 		Name:  "whitelist",
 		Usage: "Comma separated block number-to-hash mappings to enforce (<number>=<hash>)",
 	}
+	OverrideTerminalTotalDifficulty = BigFlag{
+		Name:  "override.terminaltotaldifficulty",
+		Usage: "Manually specify TerminalTotalDifficulty, overriding the bundled setting",
+	}
 	// Ethash settings
 	EthashCachesInMemoryFlag = cli.IntFlag{
 		Name:  "ethash.cachesinmem",
@@ -1492,6 +1496,10 @@ func SetEthConfig(ctx *cli.Context, nodeConfig *node.Config, cfg *ethconfig.Conf
 			cfg.Miner.GasPrice = big.NewInt(1)
 		}
 	}
+
+	if ctx.GlobalIsSet(OverrideTerminalTotalDifficulty.Name) {
+		cfg.Genesis.Config.TerminalTotalDifficulty = GlobalBig(ctx, OverrideTerminalTotalDifficulty.Name)
+	}
 }
 
 // SetDNSDiscoveryDefaults configures DNS discovery with the given URL if

turbo/cli/default_flags.go

@@ -124,4 +124,5 @@ var DefaultFlags = []cli.Flag{
 	utils.HeimdallURLFlag,
 	utils.WithoutHeimdallFlag,
 	utils.EthStatsURLFlag,
+	utils.OverrideTerminalTotalDifficulty,
 }