Persistent flags defined on non-root command, do not show up in help output of leaf command #2420

My urfave/cli version is

v3.10.0 (also verified in v3.11.0)

Checklist

• Are you running the latest v3 release? The list of releases is here.
• Did you check the manual for your release? The v3 manual is here
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Dependency Management

• My project is using go modules.

Describe the bug

When a flag is defined as persistent (Local == false), this flag is not displayed in the help output of a child command that inherits it. Only the persistent flags defined on root command are displayed under GLOBAL OPTIONS:. Note that the flag gets parsed as expected, just isn't displayed in the help output.

To reproduce

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/urfave/cli/v3"
)

func main() {
	cmd := &cli.Command{
		Name: "root",
		Flags: []cli.Flag{
			&cli.StringFlag{Name: "root-persistent", Usage: "persistent flag on root", Local: false},
		},
		Commands: []*cli.Command{
			{
				Name: "mid",
				Flags: []cli.Flag{
					&cli.StringFlag{Name: "mid-persistent", Usage: "persistent flag on mid", Local: false},
					&cli.StringFlag{Name: "mid-local", Usage: "local flag on mid", Local: true},
				},
				Commands: []*cli.Command{
					{
						Name:  "leaf",
						Flags: []cli.Flag{&cli.StringFlag{Name: "leaf-local", Usage: "local flag on leaf"}},
						Action: func(_ context.Context, c *cli.Command) error {
							fmt.Println("leaf action; mid-persistent =", c.String("mid-persistent"))
							return nil
						},
					},
				},
			},
		},
	}

	fmt.Println("=========== root mid leaf --help ===========")
	_ = cmd.Run(context.Background(), []string{"root", "mid", "leaf", "--help"})
	fmt.Println("=========== root mid --help ===========")
	_ = cmd.Run(context.Background(), []string{"root", "mid", "--help"})
	fmt.Println("=========== parse check: root mid leaf --mid-persistent=X ===========")
	if err := cmd.Run(context.Background(), []string{"root", "mid", "leaf", "--mid-persistent", "X"}); err != nil {
		fmt.Println("ERR:", err)
		os.Exit(1)
	}
}

Observed behavior

Persistent flags defined on non-root commands are absent in the help of a child command inheriting said flag.

Example output where --mid-persistent flag is declared on mid subcommand:

NAME:
   root mid leaf

USAGE:
   root mid leaf [options]

OPTIONS:
   --leaf-local string  local flag on leaf
   --help, -h           show help

GLOBAL OPTIONS:
   --root-persistent string  persistent flag on root

Expected behavior

All non-hidden inherited flags are displayed in help output of the commands inheriting them.

Additional context

I assume this is a bug, not intended behavior.

The root cause seems to be in the VisiblePersistentFlags() method, which only loops over cmd.root.Flags() and does not traverse the whole command chain.

This is in contrast to ParseFlags() method which walks the full command lineage.

Want to fix this yourself?

I'd be happy to make a contribution. The obvious solution would be to replicate similar loop as that in ParseFlags(). However, that would populate the persistent interim-command flags under the existing "GLOBAL OPTIONS:" header, which might not be entirely accurate for flags not defined on root command.

I think it would be more accurate to rename the heading to "INHERITED OPTIONS:", but would like confirmation whether this would be acceptable, and whether this is truly a bug and not intended behavior.