{% trans %} Twig tag can contain rendered expressions that return render arrays and MarkupInterface objects

Summary

The Twig translation tag, {% trans %}, works with rendered expressions ({{ }}) that return render arrays and MarkupInterface objects. Previously, only rendered expressions returning scalar values could be used inside {% trans %} tags, and other types of values would cause warnings or errors.

The following will work:

// Example render array variable built in a preprocess.
$variables['render_array'] = [
  '#prefix' => '<b>',
  '#markup' => 'render array in a trans tag',
  '#suffix' => '</b>',
];

In the Twig template which is provided the render_array variable.

{% trans %}
 This is a {{ render_array }}.
{% endtrans %}