Implements \Drupal\Core\Form\FormInterface::validateForm().
Overrides SystemConfigFormBase::validateForm
public function validateForm(array &$form, array &$form_state) {
parent::validateForm($form, $form_state);
if (empty($form['#translation_directory']) && $form_state['values']['use_source'] == LOCALE_TRANSLATION_USE_SOURCE_LOCAL) {
form_set_error('use_source', t('You have selected local translation source, but no <a href="@url">Interface translation directory</a> was configured.', array(
'@url' => url('admin/config/media/file-system'),
)));
}
}