Problem/Motivation
Drillability for Twig is important, but the scope was not clear and how to support #post_render / #theme_wrappers / drupal_render integration.
Proposed resolution
This issue frees drillability to only allow to drill-down by splitting the use case of supporting #post_render / #theme_wrappers and the rest of drupal_render into an inline_template twig tag, by replacing the actual engine render call with a method called on a twig template class.
'#render_function' => array($template, 'magicMethodName'),
Example:
{{ link }}
vs.
{% inline_template link %}
<a href="{{ attributes.href }}">{{ text }}</a>
{% endinline_template %}Remaining tasks
* Create proof-of-concept by extending macros. This inline templates are added as macros, but internally use a different Twig_Node to call drupal_render instead.
* Extend theme() to allow setting the $render_function used to render the template within the "render variables".
User interface changes
* None.
API changes
* Adding of a new twig tag.
Related Issues
#2008450: Provide for a drillable variable structure in Twig templates