[Form][OptionResolver] Support of OptionResolver 2.6 API in AbstractType

[peterrehm]

I have just tried the upgrade of an application to 2.6 and followed the upgrade document.

I noticed that there were major changes in the OptionResolver component with the depreciation
of the OptionResolverInterface. This was well documented in the OptionResolver documentation.

However it looks like there is no upgrade path for form classes extending the AbstractType since
the interface requires the OptionResolverInterface. I think we should offer an upgrade path to get
rid of the depreciation warnings. Will the AbstractType setDefaultOptions be changed in 3.0 or will
there be a new method?

@webmozart Or am I missing something?

Related symfony/symfony-docs#4159 #12156

[gondo]

exactly my thoughts, what is the recommended solution for this?

[wouterj]

Imo, there are 2 things in this subject which should be changed in the type interface:

1. With the addition of the OptionsResolver component, the setDefaultOptions method is wrong since it does a lot more
2. With the api changes in 2.6, it should typehint for OptionsResolver instead of the interface.

I think we can combine these 2 by deprecating setDefaultOptions and introducing configureOptions, which has a correct typehint.

[peterrehm]

I am fine with this, sounds reasonable. I will have a look into this.

[peterrehm]

I just submitted an PR with some initial work on this.