Change record status: 
Project: 
Introduced in branch: 
8.x
Introduced in version: 
8.0
Description: 

Language constants for language types, direction, language codes, state, etc. have all been located with bootstrap.inc and language.module. To clean up their different meanings and get them under the responsible class, we renamed and moved them to the Language class.

Drupal 8 before the change:

<?php
$a
= LANGUAGE_NOT_SPECIFIED;
$b = LANGUAGE_LOCKED;
?>

Drupal 8 after:

<?php
use Drupal\Core\Language\Language;
$a = Language::LANGCODE_NOT_SPECIFIED;
$b = Language::STATE_LOCKED;
?>

The full table of changes is follows:

Before After
LANGUAGE_SYSTEM Language::LANGCODE_SYSTEM
LANGUAGE_NOT_SPECIFIED Language::LANGCODE_NOT_SPECIFIED
LANGUAGE_NOT_APPLICABLE Language::LANGCODE_NOT_APPLICABLE
LANGUAGE_DEFAULT Language::LANGCODE_DEFAULT
LANGUAGE_CONFIGURABLE Language::STATE_CONFIGURABLE
LANGUAGE_LOCKED Language::STATE_LOCKED
LANGUAGE_ALL Language::STATE_ALL
LANGUAGE_SITE_DEFAULT Language::STATE_SITE_DEFAULT
LANGUAGE_TYPE_CONTENT Language::TYPE_CONTENT
LANGUAGE_TYPE_INTERFACE Language::TYPE_INTERFACE
LANGUAGE_TYPE_URL Language::TYPE_URL
LANGUAGE_LTR Language::DIRECTION_LTR
LANGUAGE_RTL Language::DIRECTION_RTL
Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done