Move datetime_datetime_widget_validate() to DateTimeDefaultWidget::massageFormValues()

Looks like an awesome cleanup, two questions...

+++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
@@ -123,6 +108,38 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
+        if ($date instanceOf DrupalDateTime && !$date->hasErrors()) {

In the node widget issue, I removed the hasErrors() check because that's afaik part of the element validation and it will never get this far if you don't have a valid date by then, but I could be wrong.

Wondering why you're not seeing the problem I had with the different structure here, maybe there are no tests for a datetime field that is not accessible?

Ah, now you left out the instanceof check too, that might be needed, because AFAIK, that happens when validation does fail.

Looks like those two methods are now identical apart from the field type name in the comment? Is there a reason for not making a base class for those widgets and moving it there?

will try to decouple this into base class this weekend
#2331961: Move datetime module into Core/Field is postponed on this

moved common parts to DateTimeWidgetBase

clean-up use

This looks nice, will probably need some manual testing, not sure how good the test coverage for datetime is?

Already done that:
1) the datelist widget throws the same exception when no data selected,
2) datetime works fine

But glad to get more peers on that

Yep, seems to work as good as before. Also wasn't able to reproduce any issues with #access FALSE fields.

re-roll

Committed 6bad26f and pushed to 8.0.x. Thanks!