Symfony version(s) affected

6.0.0 6.1.x-dev

Description

Consider my method: Command::configure:

    protected function configure(): void
    {
        $this->setName('app:admin:create')
            ->setDescription('Creates a new admin user')
            ->addArgument('username', InputArgument::REQUIRED, 'Sets the username of the user to create')
            ->addArgument('password', InputArgument::OPTIONAL, 'Sets the initial password for the user', fn() => $this->passwordGenerator->generatePassword());
    }

This leads to the following error:

Symfony\Component\Console\Input\InputArgument::__construct(): Argument #4 ($default) must be of type array|string|int|float|bool|null, Closure given

How to reproduce

See code in description
Running bin/console --version was enough to trigger the type error.

Take a skeleton 6.0 symfony project, include the following snippet, and try running bin/console cache:clear -vvv for full details.

<?php
namespace App\Command;

class PasswordGenerator 
{
    public function generatePassword(): string
    {
        return 'password';
    }
}

use Symfony\Component\Console\Command\Command;
class AppCommand extends Command
    private PasswordGenerator $passwordGenerator;
    protected function configure(): void
    {
        $this->passwordGenerator = new PasswordGenerator();
        $this->setName('app:admin:create')
            ->setDescription('Creates a new admin user')
            ->addArgument('username', InputArgument::REQUIRED, 'Sets the username of the user to create')
            ->addArgument('password', InputArgument::OPTIONAL, 'Sets the initial password for the user', fn() => $this->passwordGenerator->generatePassword());
    }
}

Possible Solution

I'm actually not sure about the best way to approach this, a few ideas popped into my mind:

• Widen the parameter type in InputArgument::__construct to accept mixed (no BC break)
• Narrow the parameter type in Command::addArgument to also only accept string|bool|int|float|array|null (introduces BC break)
• Narrow the parameter annotation as in the solution above, but don't change the actual function signature and then trigger a deprecation warning.
• Validate the passed $defaultValue for the correct type and throw an InvalidArgumentException in case it's an object|resource|closure. This keeps BC in the function signatures. But it doesn't really accomplish much.

Additional Context

Would be happy to work out a solution and submit a PR if this is indeed something to be fixed.
Also, I am well aware I can transform my closure into a callable array and have it work, but the point of this issue is to point out the inconsistency in argument types.