One thing I personally dislike in this implementation is the
difference between CLASS and class ... One with and one without
namespaces ...
I am not quite following. There is no functional difference between "class", "CLASS", or "Class". The parser is case insensitive with regards to keywords, which "class" or T_CLASS is on of. The code snipped I showed there was from the .phpt test that I had included in the Zend/test code base to ensure it worked and did not break existing tests.
As per the namespaced and non-namespaced blocks, I was demonstrating how ::class would resolve names regardless of if it were a FQCN or a short class name. Effectively, you can put ::class behind any "type" name and it should work as demonstrated.
-ralph