x.php

<?php 

interface foo {
}
interface bar { 
  function foo(Foo $foo);
}
class broken implements bar {
  function foo(bar $x) {}
}

y.php

<?php 
try {
  include 'z.php';
}
catch (Throwable $t) {
  echo 'caught!'; 
}

try {
  include 'x.php';
}
catch (Throwable $t) {
  echo 'caught!';
}

z.php

<?php 

Broken!