[quelsolaar]

> Such as?

Loops, function calls.... things available in C++

>Why is that a problem? It sounds like a benefit. It means that the optimization can't break anything, which to me is kind of the point

As-if is great! but the problem is that constexpr tricks people in to thinking that something is done at compile time, and the as-if rule overrides that and lets the implementation do it when ever it wants. constexpr is a feature over ridden by a fundamental rule of the language.