Issue #3274474 by mondrake, longwave, andypost, Spokje, catch, alexpott: Fix 'Access to an undefined property' PHPStan L0 errors

Issue #3041076 by alexpott, shaal, Gábor Hojtsy, lauriii, Wim Leers, catch, Cottser, jibran, andypost, znerol, xim, joelpittet, effulgentsia: Update Drupal 9 to Twig 2

Issue #2958407 by alexpott: Properly deprecate SafeMarkup::isSafe, SafeMarkup::checkPlain and the SafeMarkup class

Issue #2884675 by rodrigoaguilera, joelpittet, TR: Remove twig uses of Twig_Node::getLine to Twig_Node::getTemplateLine

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2572695 by marvin_B8, attiks, pfrenssen, xjm: Fix 'Drupal.ControlStructures.ElseIf' coding standard

Issue #2194155 by cosmicdreams, subhojit777, tatarbj, Cottser: Replace deprecated Twig_NodeInterface with recommended Twig_Node

Issue #2464045 by fgm: Move twig_render_var/twig_drupal_escape_filter to TwigExtension, inject the renderer in Twig extension and inline render() / show() function instead of calling it

Issue #1825952 by Fabianx, joelpittet, bdragon, heddn, chx, xjm, pwolanin, mikey_p, ti2m, bfr, dags, cilefen, scor, mgifford: Turn on twig autoescape by default

Issue #2212309 by joelpittet: Drupal\Core\Template and twig.engine docs, coding standards, and unused code cleanup.

Issue #2221535 by Cottser, joelpittet: TwigNodeVisitor's priority is too early and breaks some filters and macros.

Issue #2114563 by joelpittet, martin107, Cottser: Remove TwigReference with the help of 'without' filter replacing 'show'/'hide' functions.

Issue #1696786 by Fabianx, jenlampton, stevector, steveoliver, jwilson3, amateescu, chx: Integrate Twig into core: Implementation issue.