@webmozart can you review this? if my proposed behavior gets accepted, i can provide a PR for it

Thank you for reporting this issue @backbone87! :)

if my proposed behavior gets accepted

I don't find any information related to that in your description? What behavior do you propose?

always consider compound forms that have no children as rendered

idk, if this has any other implications, obviously its a behavior change and could alter the rendering results of existing code.

@backbone87 This is already the case (see https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/FormView.php#L70). Your problem is that your form contains a child, namely "components". That child is never rendered though.

Your problem can be fixed by passing the render_rest option to form_end():

{{ form_end(form, {'render_rest': false}) }}

I don't think there's anything we can fix on our side.

@webmozart Its about inconsistency: using the tpl code from the OP, we observe 2 cases:

• form.components has children (the for loop gets called for each of them and output them with form_row): form_end will just close the form tag, because it considers form.components to be rendered, because form.components is compound and all children are rendered.
• form.components has no children (the for loop gets not called and the else branch is executed): form_end will render form.components and close the form tag, because it considers form.components not to be rendered, but the condition form.components is compound and all children are rendered still applies.

ok that description wasnt as good as i expected. ok, lets try this with another one:
the current check of isRendered: rendered flag is set OR (form has at least one child AND each child is rendered)
my proposed check: rendered flag is set OR (form is compound AND each child is rendered)

if form is not empty, both checks always return the same bool. but if the form is an empty compound form my check will consider it rendered, while the current one doesnt.

a similar reasoning for checking compound vs. checking number of children is given here:
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/Form.php#L549

compare this to: https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Form/FormView.php#L68

my proposed change:

    public function isRendered()
    {
        if ($this->rendered) {
            return true;
        }

        if (!$this->vars->compound) {
            return false;
        }

        foreach ($this->children as $child) {
            if (!$child->isRendered()) {
                return false;
            }
        }

        return $this->rendered = true;
    }

@backbone87 Sounds reasonable. The change should only affect form_rest() (or form_end()) statements, which aren't commonly used to render rows in the first place, so the implication on existing applications should be minimal.

and update on this?

the current check of isRendered: rendered flag is set OR (form has at least one child AND each child is rendered)
my proposed check: rendered flag is set OR (form is compound AND each child is rendered)

@backbone87 It seems that @webmozart said that it "sounds reasonable" so please open a PR :)