This is cool, definitely new to me. I do wonder if this just moves the problem though. As the article explains:

> One crucial requirement is that the counter must be initialized before the first reference to the flexible-array member. Another requirement is that the array must always contain at least as many elements as indicated by the counter.

This means as the array is initialized and updated, you must keep the counter updated with it. Its just as easy to screw that up than it is to screw up the general problem of accessing elements that are out-of-bounds