“surprising” constant initialization because of definition order

Question

When reading the slides about constexpr the introduction is about \"surprisingly dynamic initialization with consts\". The example is

struct S {
    st         


        

Answer 1

You can find out whether a constant is statically or dynamically initialised by trying to declare an array:

struct S {
    static const int c;
};
const int d = 10 * S::c; // (1)
const int S::c = 5;      // (2)

static char array[d];

This code fails in g++ version 4.7.0, because d is dynamically initialised. And if you exchange (1) and (2), it compiles, because now d is statically initialised. But I can't find another way to fix it, using constexpr.