Positional arguments order in clap 3.x

[JohnnyJayJay]

Is it possible to determine the order of the positional arguments with the macro system?
I have this code:

#[derive(Clap)]
#[clap(version = "0.1.0", author = "JohnnyJayJay")]
pub struct MainOpts {
    /// File to output the result of the operation to.
    #[clap(short, long, value_name = "FILE")]
    pub output: Option<PathBuf>,
    #[clap(subcommand)]
    pub cmd: SubCommand,
    /// input file
    #[clap(index = 1)]
    pub file: PathBuf,
}

And I want it to be interpreted like this: <SUBCOMMAND> <FILE> but instead it becomes <FILE> <SUBCOMMAND>.

[pksunkara]

Have you tried changing the order of the fields?

[JohnnyJayJay]

Yes. Doesn't make a difference. I presume it's ordered alphabetically?
Nvm it isn't, just checked.

[pksunkara]

You can use the index(0) method.

#[clap(short, long, value_name = "FILE", index = 1)]
#[clap(short, long, value_name = "SUBCOMMAND", index = 0)]

[JohnnyJayJay]

I've tried, but this results in a compile error:

error: methods in attributes are not allowed for subcommand
  --> mimavm\src\cli.rs:18:12
   |
18 |     #[clap(subcommand, index = 0)]
   | 

[pksunkara]

Oh subcommand is not a positional argument. It will always come after other args. If you want FILE to be part of subcommand, you need to move it to be under subcommand.

[JohnnyJayJay]

Ok, so there is no way to express that all subcommands need this argument other than repeating it?

[pksunkara]

You can set global = true which makes it a global argument that can be used anywhere.

[JohnnyJayJay]

Got it. This is not applicable to my use case, but I ended up restructuring everything a little so there is no issue anymore now. Thanks

[mokeyish]

Can positional arguments be in any order? That is, whether the argument content is consumed depends on whether the parsing is successful.

[mokeyish]

The dig command can be like this, query-type and domain can be in any order.