In PHP why does \Foo\Bar::class not generate an error when the class doesn't exist?

Question

Why does

<?php
namespace Foo;
echo Bar::class;

output Foo\\Bar without any errors, warnings, or notices? I would have expected some sort of "Class does not exist" message.

Answer 1

From PHP's document

The class name resolution using ::class is a compile time transformation. That means at the time the class name string is created no autoloading has happened yet. As a consequence, class names are expanded even if the class does not exist. No error is issued in that case.

So, it is documented and an expected behavior