Rustのclapで必須なサブコマンドのあるコマンドを作るときはarg_required_else_help(false)を書かないと引数なしで実行したときにエラーじゃなくてヘルプが表示されるの想定外

use std::path::PathBuf;

use clap::{Args, Parser, Subcommand};

#[derive(Debug, Parser)]
#[command(version)]
struct Opt {
    #[command(subcommand)]
    command: Command,
}

#[derive(Debug, Subcommand)]
enum Command {
    /// Add file.
    Add(Add),

    /// Remove file.
    Remove(Remove),
}

#[derive(Args, Debug)]
pub struct Add {
    /// File to add.
    file: Option<PathBuf>,
}

#[derive(Args, Debug)]
pub struct Remove {
    /// File to remove.
    file: Option<PathBuf>,
}

fn main() {
    let opt = Opt::parse();
    println!("{opt:?}");
}

@@ -3,7 +3,7 @@
 use clap::{Args, Parser, Subcommand};
 
 #[derive(Debug, Parser)]
-#[command(version)]
+#[command(version, arg_required_else_help(false))]
 struct Opt {
     #[command(subcommand)]
     command: Command,