XHPAST does not detect a syntax error with the following code (specifically, the `ArcanistXHPASTLinter` does not raise any issues):
```lang=php
<?php
class Foo {
public final final function bar() {}
}
```
`php -l` does recognise this code as a syntax error:
```
> php -l test.php
PHP Fatal error: Multiple final modifiers are not allowed in test.php on line 5
Errors parsing test.php
```