MutuallyExclusiveFlags persistent flags are not propagated to subcommands

[siutsin]

My urfave/cli version is

latest main (commit fd14621)

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
• Did you perform a search about this problem? Here's the GitHub guide about searching.

Dependency Management

• My project is using go modules.

Describe the bug

Persistent flags defined within MutuallyExclusiveFlags on a parent command are not propagated to subcommands. This is because the persistent flag inheritance loop in parseFlags (command_parse.go:39) iterates over pCmd.Flags instead of pCmd.allFlags().

allFlags() (defined in command.go:197) returns both cmd.Flags and all flags from cmd.MutuallyExclusiveFlags groups. Because parseFlags only walks pCmd.Flags, flags from MutuallyExclusiveFlags groups are never added to the subcommand's appliedFlags, making them unrecognised when passed after a subcommand name.

To reproduce

package main

import (
	"context"
	"fmt"
	"os"

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

func main() {
	cmd := &cli.Command{
		Name: "root",
		MutuallyExclusiveFlags: []cli.MutuallyExclusiveFlags{
			{
				Flags: [][]cli.Flag{
					{&cli.StringFlag{Name: "alpha"}},
					{&cli.StringFlag{Name: "beta"}},
				},
			},
		},
		Commands: []*cli.Command{
			{
				Name: "sub",
				Action: func(_ context.Context, cmd *cli.Command) error {
					fmt.Println(cmd.String("alpha"))
					return nil
				},
			},
		},
	}

	if err := cmd.Run(context.Background(), os.Args); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

Run with:

go run main.go sub --alpha hello

Observed behavior

flag provided but not defined: -alpha

Expected behavior

The --alpha flag should be recognised by the subcommand and print hello, since persistent flags (flags with Local defaulting to false) should propagate to subcommands regardless of whether they are defined in Flags or MutuallyExclusiveFlags.

A flag defined directly in Flags with the same configuration works correctly:

cmd := &cli.Command{
    Name: "root",
    Flags: []cli.Flag{
        &cli.StringFlag{Name: "alpha"},
    },
    Commands: []*cli.Command{
        {Name: "sub", Action: func(_ context.Context, cmd *cli.Command) error {
            fmt.Println(cmd.String("alpha")) // prints "hello"
            return nil
        }},
    },
}

Additional context

The fix is a one-line change in command_parse.go:39:

- for _, fl := range pCmd.Flags {
+ for _, fl := range pCmd.allFlags() {

Want to fix this yourself?

Yes, happy to submit a PR (#2266) with the fix and a test.

Run go version and paste its output here

go version go1.26.0 darwin/arm64

Run go env and paste its output here

AR='ar'
CC='cc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='c++'
GCCGO='gccgo'
GO111MODULE='on'
GOARCH='arm64'
GOARM64='v8.0'
GODEBUG=''
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOOS='darwin'
GOROOT='/opt/homebrew/opt/go/libexec'
GOVERSION='go1.26.0'