title: Strange DateTime behaviour in date validation in php 5.4
body: <p>I wrote a simple piece of code to validate the format of a date.
  The format of the date in my case is d/m/y</p>
  
  <p>List of tests that I run successfully</p>
  
  <p>10/12/2019 DATE OK</p>
  
  <p>aa/12/2019 DATE KO</p>
  
  <p>10-12-2019 DATE KO</p>
  
  <p>But there is this case that surprises me:</p>
  
  <p>32/12/2019 DATE OK</p>
  
  <p>Why does this happen?
  Do I need to add controls on the range of days and months?</p>
  
  <pre><code>$value = '32-12-2019';
  $checkDate = \DateTime::createFromFormat('d/m/Y', $value);
  if ($checkDate) {
      print("DATE OK");
  } else {
      print("DATE KO");
  }
  </code></pre>