Fix nested subform settings

[vith]

Form settings were not being maintained when subforms are involved. If a subform changed a form setting, the parent form would inherit the new value from the subform after the subform was rendered.

I'm assuming the reverse-inheritance wasn't an intended behavior. This patch saves and restores form settings as a stack so that parent forms have their original state after a subform ends.

[vith]

Not sure what the hhvm test failure is; doesn't look like it was me.

[florianeckerstorfer]

Thanks for the PR.

The HHVM tests fail because of a bug in HHVM (see facebook/hhvm#3797), it's already been fixed but it seems that v3.3.1 has not been deployed to Travis CI yet.

I'm not really sure if it is a good idea to throw an Exception when the stack is empty? Wouldn't it be better to fall back to the defaults?

[vith]

It seems to me that situation would be equivalent to having unbalanced pairings of opening and closing <form></form> tags on the page. It shouldn't be possible at all unless something goes very wrong, or someone manually calls the internal-use-only functions I added. Personally I would rather have the thing blow up if that somehow happens.

If you want a way to restore the defaults maybe that should be a separate function?

But if you still would rather it restore defaults let me know and I will change it.

[florianeckerstorfer]

Ok, thanks for the explanation for this behaviour.

[vith]

@althaus How are you triggering {% block form_end %} without {% block form_start %}? I don't explicitly call {{ form_start(form) }} in my templates. The start and end are implicit when using {{ form(form) }}.

[althaus]

@vith We had some rare cases, where we had to manually render the <form> tag and then just used {{ form_end(form) }} to finalize the form with CSRF and end tag.

Nevertheless the reason I had more trouble than expected was our custom {% block form_start %} which included my patch for bootstrap-bundle which got merged inbetween (d81a349) and I just missed to remove it after updating to latest master. So sorry for causing the confusion.