Type error caused by FormBuilderIterator

[dmaicher]

Environment

• PHP 8.1
• latest Symfony 6.1
• latest Sonata packages

Subject

Type error caused by FormBuilderIterator

Minimal repository with the bug

?

Steps to reproduce

I have an inline admin where I can add new items in a table view. If I press the "add" button then I get a type error since I moved to Symfony 6. It worked fine with Symfony 5.4 as there was no string typehint on Symfony's FormBuilder::get.

Actual results

A dump of

    public function current(): FormBuilderInterface
    {
        if ($this->iterator->current() === 0) {
            dd($this);
        }

        return $this->formBuilder->get($this->iterator->current());
    }

From what I can tell we cannot guarantee that $this->iterator->current() within FormBuilderIterator will actually be a string. In my case its an integer and this seems legit. The problematic form field is an expanded choice field with checkboxes and the children of this form are indexed with integers.

I checked it and casting to string there solves the issue for me. Shall I create a PR for this?

    public function current(): FormBuilderInterface
    {
        return $this->formBuilder->get((string) $this->iterator->current());
    }

[dmaicher]

Might be related to symfony/symfony#46698 @VincentLanglet 🤔

[VincentLanglet]

Yeah, it was reported here sonata-project/form-extensions#368 (comment)