internal/flags: remove low-use type TextMarshalerFlag (#30707)

Currently we have a custom TextMarshalerFlag. It's a nice idea, allowing
anything implementing text marshaller to be used as a flag. That said,
we only ever used it in one place because it's not that obvious how to
use and it needs some boilerplate on the type itself too, apart of the
heavy boilerplate got the custom flag.

All in all there's no *need* to drop this feature just now, but while
porting the cmds over to cli @V3, all other custom flags worker
perfectly, whereas this one started crashing deep inside the cli
package. The flag handling in v3 got rebuild on generics and there are a
number of new methods needed; and my guess is that maybe one of them
doesn't work like this flag currently is designed too.

We could definitely try and redesign this flag for cli v3... but all
that effort and boilerplate just to use it for 1 flag in 1 location,
seems not worth it. So for now I'm suggesting removing it and maybe
reconsider a similar feature in cli v3 with however it will work.

cmd/utils/flags.go

@@ -211,8 +211,7 @@ var (
 		Value: 0,
 	}
 
-	defaultSyncMode = ethconfig.Defaults.SyncMode
-	SnapshotFlag    = &cli.BoolFlag{
+	SnapshotFlag = &cli.BoolFlag{
 		Name:     "snapshot",
 		Usage:    `Enables snapshot-database mode (default = enable)`,
 		Value:    true,
@@ -244,10 +243,10 @@ var (
 		Usage:    "Manually specify the Verkle fork timestamp, overriding the bundled setting",
 		Category: flags.EthCategory,
 	}
-	SyncModeFlag = &flags.TextMarshalerFlag{
+	SyncModeFlag = &cli.StringFlag{
 		Name:     "syncmode",
 		Usage:    `Blockchain sync mode ("snap" or "full")`,
-		Value:    &defaultSyncMode,
+		Value:    ethconfig.Defaults.SyncMode.String(),
 		Category: flags.StateCategory,
 	}
 	GCModeFlag = &cli.StringFlag{
@@ -1669,7 +1668,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 	if ctx.IsSet(SyncTargetFlag.Name) {
 		cfg.SyncMode = downloader.FullSync // dev sync target forces full sync
 	} else if ctx.IsSet(SyncModeFlag.Name) {
-		cfg.SyncMode = *flags.GlobalTextMarshaler(ctx, SyncModeFlag.Name).(*downloader.SyncMode)
+		if err = cfg.SyncMode.UnmarshalText([]byte(ctx.String(SyncModeFlag.Name))); err != nil {
+			Fatalf("invalid --syncmode flag: %v", err)
+		}
 	}
 	if ctx.IsSet(NetworkIdFlag.Name) {
 		cfg.NetworkId = ctx.Uint64(NetworkIdFlag.Name)

internal/flags/flags.go

@@ -17,7 +17,6 @@
 package flags
 
 import (
-	"encoding"
 	"errors"
 	"flag"
 	"fmt"
@@ -122,119 +121,6 @@ func (f *DirectoryFlag) GetDefaultText() string {
 	return f.GetValue()
 }
 
-type TextMarshaler interface {
-	encoding.TextMarshaler
-	encoding.TextUnmarshaler
-}
-
-// textMarshalerVal turns a TextMarshaler into a flag.Value
-type textMarshalerVal struct {
-	v TextMarshaler
-}
-
-func (v textMarshalerVal) String() string {
-	if v.v == nil {
-		return ""
-	}
-	text, _ := v.v.MarshalText()
-	return string(text)
-}
-
-func (v textMarshalerVal) Set(s string) error {
-	return v.v.UnmarshalText([]byte(s))
-}
-
-var (
-	_ cli.Flag              = (*TextMarshalerFlag)(nil)
-	_ cli.RequiredFlag      = (*TextMarshalerFlag)(nil)
-	_ cli.VisibleFlag       = (*TextMarshalerFlag)(nil)
-	_ cli.DocGenerationFlag = (*TextMarshalerFlag)(nil)
-	_ cli.CategorizableFlag = (*TextMarshalerFlag)(nil)
-)
-
-// TextMarshalerFlag wraps a TextMarshaler value.
-type TextMarshalerFlag struct {
-	Name string
-
-	Category    string
-	DefaultText string
-	Usage       string
-
-	Required   bool
-	Hidden     bool
-	HasBeenSet bool
-
-	Value TextMarshaler
-
-	Aliases []string
-	EnvVars []string
-}
-
-// For cli.Flag:
-
-func (f *TextMarshalerFlag) Names() []string { return append([]string{f.Name}, f.Aliases...) }
-func (f *TextMarshalerFlag) IsSet() bool     { return f.HasBeenSet }
-func (f *TextMarshalerFlag) String() string  { return cli.FlagStringer(f) }
-
-func (f *TextMarshalerFlag) Apply(set *flag.FlagSet) error {
-	for _, envVar := range f.EnvVars {
-		envVar = strings.TrimSpace(envVar)
-		if value, found := syscall.Getenv(envVar); found {
-			if err := f.Value.UnmarshalText([]byte(value)); err != nil {
-				return fmt.Errorf("could not parse %q from environment variable %q for flag %s: %s", value, envVar, f.Name, err)
-			}
-			f.HasBeenSet = true
-			break
-		}
-	}
-	eachName(f, func(name string) {
-		set.Var(textMarshalerVal{f.Value}, f.Name, f.Usage)
-	})
-	return nil
-}
-
-// For cli.RequiredFlag:
-
-func (f *TextMarshalerFlag) IsRequired() bool { return f.Required }
-
-// For cli.VisibleFlag:
-
-func (f *TextMarshalerFlag) IsVisible() bool { return !f.Hidden }
-
-// For cli.CategorizableFlag:
-
-func (f *TextMarshalerFlag) GetCategory() string { return f.Category }
-
-// For cli.DocGenerationFlag:
-
-func (f *TextMarshalerFlag) TakesValue() bool     { return true }
-func (f *TextMarshalerFlag) GetUsage() string     { return f.Usage }
-func (f *TextMarshalerFlag) GetEnvVars() []string { return f.EnvVars }
-
-func (f *TextMarshalerFlag) GetValue() string {
-	t, err := f.Value.MarshalText()
-	if err != nil {
-		return "(ERR: " + err.Error() + ")"
-	}
-	return string(t)
-}
-
-func (f *TextMarshalerFlag) GetDefaultText() string {
-	if f.DefaultText != "" {
-		return f.DefaultText
-	}
-	return f.GetValue()
-}
-
-// GlobalTextMarshaler returns the value of a TextMarshalerFlag from the global flag set.
-func GlobalTextMarshaler(ctx *cli.Context, name string) TextMarshaler {
-	val := ctx.Generic(name)
-	if val == nil {
-		return nil
-	}
-	return val.(textMarshalerVal).v
-}
-
 var (
 	_ cli.Flag              = (*BigFlag)(nil)
 	_ cli.RequiredFlag      = (*BigFlag)(nil)

internal/flags/helpers.go

@@ -256,9 +256,6 @@ func AutoEnvVars(flags []cli.Flag, prefix string) {
 		case *BigFlag:
 			flag.EnvVars = append(flag.EnvVars, envvar)
 
-		case *TextMarshalerFlag:
-			flag.EnvVars = append(flag.EnvVars, envvar)
-
 		case *DirectoryFlag:
 			flag.EnvVars = append(flag.EnvVars, envvar)
 		}