Hidden subcommands shown when "requires a subcommand but one was not provided"

[devjgm]

Please complete the following tasks

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

Rust Version

rustc 1.74.0 (79e9716c9 2023-11-13)

Clap Version

4.5.4

Minimal reproducible code

use clap::{Parser, Subcommand};

#[derive(Parser, Debug)]
#[clap(version, about)]
struct Cli {
    #[clap(subcommand)]
    command: Command,

    #[clap(long)]
    message: String,
}

#[derive(Subcommand, Debug)]
enum Command {
    Hello,
    #[clap(hide = true)]
    Secret,  // <------ This subcommand is marked hidden and shouldn't be suggested to the user
}

fn main() {
    let cli = Cli::parse();
    match cli.command {
        Command::Hello => println!("Hello {}", cli.message),
        Command::Secret => println!("Secret {}", cli.message),
    }
}

Steps to reproduce the bug with the above code

$ cargo run -- --message foo
    Finished dev [unoptimized + debuginfo] target(s) in 0.03s
     Running `target/debug/clap-repro --message foo`
error: 'clap-repro' requires a subcommand but one was not provided
  [subcommands: hello, secret, help]

Usage: clap-repro --message <MESSAGE> <COMMAND>

For more information, try '--help'.

Actual Behaviour

The problem is that the secret subcommand is marked as hidden, yet it is suggested as one of the possible subcommands in the list [subcommands: hello, secret, help]

Expected Behaviour

Since the secret subcommand is marked as hidden, it should not be suggested to the user in the list of possible subcommands. So
Actual: [subcommands: hello, secret, help]
Expected: [subcommands: hello, help]

Additional Context

The --message flag in the repro case seems to be important. If I remove it and omit the subcommand, it sees that no arguments are provided and simply displays the normal help message, which correctly omits the hidden subcommand.

Debug Output

No response

[epage]

FYI #4853 is a different place hidden subcommands can show up in errors