You are right. But I don't see what we can do here without break BC. The solution for you would be to pass an anonymous function that just returns the string.

In other places, we deprecated the ability to pass callables as string to avoid such issues. That's something we could do here in 4.1 too so that we can remove support for it in 5.0.

@xabbuh Do we still have more places like that? That sounds like an ugly pitfall in general.

I think it's very likely that we have similar code in other places.

Maybe, a similar problem can be here, here and here.

@peter-gribanov I totally agree about FileType, that's the very same mechanism.

I'm not sure about DefaultChoiceListFactory though. Here it's either a callable or an array and callable arrays should have a different structure than the mapping arrays that we expect here.

I'm not sure about DefaultChoiceListFactory though. Here it's either a callable or an array and callable arrays should have a different structure than the mapping arrays that we expect here.

@derrabus it may seem absurd, but it's still possible.

This code seems innocuous:

$builder->add('body', ChoiceType::class, array(
    'attr' => ['title' => 'sum'],
));

But everything can turn out to be very unexpected if the project has such class:

class Title
{
    public static function sum($x, $y)
    {
        return sprintf('Sum x + y = %d', $x + $y);
    }
}

@peter-gribanov No, because to call the class in your example, the array would be ['title', 'sum'] and not ['title' => 'sum'].

@derrabus exactly. sorry 🙇