Date values are not being saved when field is used in a nested field collection

It seems to be a problem related to #field_parents and #parents in date_combo_validate . I don't know if this is the right answer as I don't know the theory and I don't have time to test right now, but I changed the following lines at 454 in date_elements.inc from

  $item = drupal_array_get_nested_value($form_values, $element['#parents']);
  $posted = drupal_array_get_nested_value($form_input, $element['#parents']);

to

  $item = drupal_array_get_nested_value($form_state['values'], $element['#parents']);
  $posted = drupal_array_get_nested_value($form_state['input'], $element['#parents']);

And the dates seem to be getting saved now.

I am more confident about this change now. I have looked more at the values of #parents and #field_parents and it looks like #parents always includes the elements from #field_parents plus a few more that identify the field itself.

The current code works on dates directly in the top level of an entity since #field_parents is empty and #parents just has info about the field, but when a date is inside a field collection it breaks because it assumes that #parents will still only have info about the field itself when it actually contains all the info from #field_parents as well.

I have tested this fix on a date inside a field collection and a date nested a level deeper than that inside another field collection.

2: date-parents_fix-1580032-2.patch queued for re-testing.

#2 looks good for me
good to see here test

Committed c4c0522 and pushed to 7.x-2.x. lets add test cases now.

#2 worked for me too~

Lets add testcase as sepate issue then