simplexml_load_file parser error with ampersands in urls

Dennis Nezic <dennisn@xxxxxxxxxxxxxxxx> · Sat, 4 Jun 2022 21:52:23 -0400

If there are ampersands (&) in links within tags (eg. href= url=
rel=) simplexml_load_file() fails with

  parser error : EntityRef: expecting ';'

This useful comment in the manual suggests str_replace()'ing it with
the &amp; entity:

  https://www.php.net/manual/en/function.simplexml-load-file.php#117566

%26 url encoding also works, although no other character that
I'm aware of seems to cause this parser error / requires
urlencode()'ing.

But this seems like a bug, or something that simplexml_load_file should
be able to handle? Or does xml or something not allow &'s in tag
properties?

For example, trying to load this file:

<?xml version="1.0"?>
<feed xmlns="http://www.w3.org/2005/Atom";>
  <entry>
    <link href="http://example.com/bla.php?yes&no"; />
  </entry>
</feed>