Add mut_group to Command

[rgiot]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Clap Version

4.3.12

Describe your use case

I use a Command object that has been defined in another crate. This command has a group defined this way:

    .group(
        ArgGroup::new("ANY_INPUT")
            .args(&["INLINE", "INPUT", "LIST_EMBEDDED", "VIEW_EMBEDDED"])
    )

I modify this object in my crate to add some additional arguments and especially this one (I do not want to relly on the default implementation of version) :

            .arg(
                Arg::new("version")
                    .long("version")
                    .short('V')
                    .help("Print version")
                    .action(ArgAction::SetTrue)
                    .exclusive(true) // does not seem to work
                    .conflicts_with_all(["ANY_INPUT", "INLINE", "INPUT", "LIST_EMBEDDED", "VIEW_EMBEDDED"])
            )

both exclusive and conflicts_with_all and seems to be ignored, so as a workaround I have temporarily modified the Command definition in the other crate (so it does not fit the need of this initial crate

    .group(
        ArgGroup::new("ANY_INPUT")
            .args(&["INLINE", "INPUT", "LIST_EMBEDDED", "VIEW_EMBEDDED"])
          //  .required(true)
            .conflicts_with("version")
    )

Describe the solution you'd like

Clap already has mut_arg and mut_subcommand.
It would be nice to add mut_group to be consistent.

The solution to my problem would not require anymore to modify the former crate; only to code something similar to

command.mut_group("ANY_INPUT", |group| group.required(false).conflicts_with("version'))

I would say that the implementation of mut_group would be close to

pub fn mut_group<F>(mut self, arg_id: impl AsRef<str>, f: F) -> Self
    where
        F: FnOnce(ArgGroup) -> ArgGroup {
        let group = ... code to get the position, remove from the appropriate vec, handle absence ...
        self.groups.push(f(group));
        self
    }

Alternatives, if applicable

No response

Additional Context

For sure, this mut_group is of interest as it is missing from the library. But I wonder if in my use case it is just a workaround around a bug in the management of conflicting arguments

[epage]

```rust
            .arg(
                Arg::new("version")
                    .long("version")
                    .short('V')
                    .help("Print version")
                    .action(ArgAction::SetTrue)
                    .exclusive(true) // does not seem to work
                    .conflicts_with_all(["ANY_INPUT", "INLINE", "INPUT", "LIST_EMBEDDED", "VIEW_EMBEDDED"])
            )

both exclusive and conflicts_with_all and seems to be ignored, so as a workaround I have temporarily modified the Command definition in the other crate (so it does not fit the need of this initial crate

...

For sure, this mut_group is of interest as it is missing from the library. But I wonder if in my use case it is just a workaround around a bug in the management of conflicting arguments

I feel like the first discussion to be having is about conflicts and exclusive...

[rgiot]

You mean by added a dedicated issue with a minimal working example? Or I am misusing something?
(Jtlyk, I added the conflict when I noticed the exclusive was not working)

[epage]

That'd work, thanks!

[rgiot]

here is the accompanying issue #5041

[Hawk777]

I would like to reiterate that this would be really nice to have. My use case is that I want to use the derive API, but I want a specific ArgGroup to sometimes be required and sometimes be optional depending on information discovered at runtime. I’m currently working around it by not using a group and then conditionally using arg_mut to create required_unless_present relationships between the two arguments; however, the help output is not as nice that way (it just claims that both arguments are required, even though really only one or the other is), so I would prefer to use a group—but I can’t make a derived group conditionally required, because I can’t mutate the group at runtime!

[epage]

@Hawk777 thanks for the use case! Opened #5247 to address it.