#pattern property causing error in D7

After creating an element like this:

$form['tel'] = array(
  '#type'=>'telfield',
  '#title'=>'Votre numéro de téléphone',
  '#title_display'=>'invisible',
  '#placeholder' => 'Votre numéro de téléphone',
  '#pattern'=>'\+?[0-9+*#,;]+',
   '#attributes' => array(
    'class'=>array('tooltip-me'),
  )
);

I get the following error:
Fatal error: Call to undefined function form_validate_pattern() in /home/fullwebfactory/svn_trunk/drupal/includes/form.inc on line 1410

It appears to me that the following function from elements.module is calling a drupal 8 core function, "form_validate_pattern", that is not available in D7.

function elements_process_pattern($element) {
  if (isset($element['#pattern']) && !isset($element['#attributes']['pattern'])) {
    $element['#attributes']['pattern'] = $element['#pattern'];
    $element['#element_validate'][] = 'form_validate_pattern';
  }

  return $element;
}