custom suggestions on drupal views

Problem/Motivation

it does not seem possible to add template suggestions depending on the content view mode display chosen

Steps to reproduce

function mytheme_preprocess_views_view(&$variables) {

  if ($variables['view']->id() === 'article') {
    $row_view_mode = $variables['view']->getDisplay()->getOption('row')['settings']['view_mode'];

    if (!empty($row_view_mode)) {
      $variables['theme_hook_suggestions'][] = 'views_view__article__$row_view_mode;
    }
  }
}

$row_view_mode= 'teaser_podcast'
$variables['view']->current_display === 'block_7'

views-view--article--teaser-podcast.html.twig is not taken
views-view--article--block-7.html.twig is taken even without the hook

Proposed resolution

allows custom suggestion templates

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet