It is part of both, the technique described is not the only way to reach a solution for the given problem (implementing a counter usable in constant-expressions).
In other words; if one sees this as a "bug" in the ISO C++ Standard, the "problem" is a lot deeper than friendly definitions (the technique used in the post).
C++ is a complex language, where many rules touch upon other, and with that it is not surprising that some rules can be bent to allow behavior which was perhaps never intended.
Future posts (probably after part 3) will address the philosophy of the "exploit", other techniques that boil down to doing the same thing, as well as proposed (ISO Standard) wording to "fix" the "problem" - if that is the path being walked.