html_tag self-closes tag with NULL #value

Problem/Motivation

drupal_pre_render_html_tag() is not specific in allowing which tags can be void (self-closed).

Proposed resolution

Only allow void elements to self close.

Remaining tasks

• Create patch.

User interface changes

None

API changes

None.

Original report:

Just ran into this with a 7.x site:

      $build => array(
        '#theme' => 'html_tag',
        '#tag' => 'section',
        '#value' => views_embed_view('articles', 'list'),
      );

Unfortunately views_embed_view returned NULL because I forgot that view didn't have a list display. I noticed though that suddenly my page looked all sorts of wacked out and found the issue:

<section />

Um, that should never happen. Started digging and realized the culprit was that it was simply checking if (!isset($element['#value'])) { to determine whether a tag can be self closed. This is un-acceptable. Double checked and the issue still exists in drupal_pre_render_html_tag()