For users upgrading from 2.3 to 2.7, there are a lot of deprecation warnings aroundChoiceList,SimpleChoiceList andChoiceListInterface. The recommendation is to useArrayChoiceList instead. However, there currently isn't any documentation about how to use that, and the current 2.7 documentation suggests using the deprecatedChoiceList. Seehttp://symfony.com/doc/current/reference/forms/types/choice.html#choice-list

This is a very complicated area of Symfony forms which has been in a bit of flux due to potential API changes, so it would be good to have some examples of usage.

I'd update the docs myself, but I haven't figured out howArrayChoiceList actually works yet.