Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

Comment constants for comment visibility were located in comment.module. To clean up and get it under the responsible class, they were renamed and moved to Drupal\comment\Plugin\Field\FieldType\CommentItemInterface.

Drupal 7 and 8 before the change:

$options = array(
  COMMENT_OPEN => t('Open'),
  COMMENT_CLOSED => t('Closed'),
  COMMENT_HIDDEN => t('Hidden'),
);

Drupal 8 after:

use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;

$options = array(
  CommentItemInterface::OPEN => t('Open'),
  CommentItemInterface::CLOSED => t('Closed'),
  CommentItemInterface::HIDDEN => t('Hidden'),
);
Impacts: 
Module developers