Consider add mutually exlusive flag marker

[Dentrax]

Required case:

var cmdFoo = &cobra.Command{
	Use:   "foo {-a A | -b B}",
	...
}

cmdFoo.Flags().StringVarP(&a, "a", "a", "", "a")
cmdFoo.Flags().StringVarP(&b, "b", "a", "", "a")
_ = cmdFoo.MarkFlagRequired("a")
_ = cmdFoo.MarkFlagRequired("b")

We can not set them both at the same time, but one of the -a or -b is required. (See: #1358) We may need something like:

func (c *Command) MarkFlagMutuallyExlusive(flag string, otherFlags ...string) error

Optional case:

var cmdFoo = &cobra.Command{
	Use:   "foo [-a A | -b B]",
	...
}

cmdFoo.Flags().StringVarP(&a, "a", "a", "", "a")
cmdFoo.Flags().StringVarP(&b, "b", "a", "", "a")

i.e.:

_ = cmdFoo.MarkFlagMutuallyExlusive("a", "b")

Should error out, i.e.:

required flag(s) "a" or "b" not set
exit status 1

Current workaround:

	PreRunE: func(cmd *cobra.Command, args []string) error {
		if a != "" && b != "" {
			return fmt.Errorf("--a and --b are mutually exclusive, can not be set at the same time")
		}
		if a == "" || b == "" {
			return fmt.Errorf("one of the --a or --b are required")
		}
		return nil
	},

[jef]

Duplicate of #1216

[github-actions]

This issue is being marked as stale due to a long period of inactivity

[johnSchnake]

Closing as duplicate; thanks for linking the other issue @jef