The solution I found for this was to copy this file from the Bootstrap theme directory
src/Plugin/Form/SearchBlockForm.php
to the same location in your sub-theme.
Then you can set the icon_only property to FALSE.
e.g.
<?php
/**
* @file
* Contains \Drupal\subtheme\Plugin\Form\SearchBlockForm.
*/
namespace Drupal\subtheme\Plugin\Form;
use Drupal\bootstrap\Annotation\BootstrapForm;
use Drupal\bootstrap\Plugin\Form\FormBase;
use Drupal\bootstrap\Utility\Element;
use Drupal\Core\Form\FormStateInterface;
/**
* Implements hook_form_FORM_ID_alter().
*
* @ingroup plugins_form
*
* @BootstrapForm("search_block_form")
*/
class SearchBlockForm extends FormBase {
/**
* {@inheritdoc}
*/
public function alterFormElement(Element $form, FormStateInterface $form_state, $form_id = NULL) {
$form->actions->submit->setProperty('icon_only', FALSE);
$form->keys->setProperty('input_group_button', FALSE);
}
}
I still think there must be an easier way... but until then.