cmd/geth: dont fail on deprecated toml config fields (#23118)

cmd/geth/config.go

@@ -31,6 +31,7 @@ import (
 	"github.com/ethereum/go-ethereum/eth/catalyst"
 	"github.com/ethereum/go-ethereum/eth/ethconfig"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/params"
@@ -63,7 +64,12 @@ var tomlSettings = toml.Config{
 		return field
 	},
 	MissingField: func(rt reflect.Type, field string) error {
-		link := ""
+		id := fmt.Sprintf("%s.%s", rt.String(), field)
+		if deprecated(id) {
+			log.Warn("Config field is deprecated and won't have an effect", "name", id)
+			return nil
+		}
+		var link string
 		if unicode.IsUpper(rune(rt.Name()[0])) && rt.PkgPath() != "main" {
 			link = fmt.Sprintf(", see https://godoc.org/%s#%s for available fields", rt.PkgPath(), rt.Name())
 		}
@@ -228,3 +234,7 @@ func applyMetricConfig(ctx *cli.Context, cfg *gethConfig) {
 		cfg.Metrics.InfluxDBTags = ctx.GlobalString(utils.MetricsInfluxDBTagsFlag.Name)
 	}
 }
+
+func deprecated(field string) bool {
+	return false
+}