C++: avoid optimizing out variable

Question

I have some useful code in constructor or class Valuable. I want be sure it's executed before submain. How can I guarantee that it's not optimized out?

int main()
{
    // Dear compiler, please don't optimize ctor call out!
    Valuable var;

    return submain();
}

Is local variable enough? Do I need to use static:

static Valuable *v = new Valuable();
delete v;
v = NULL;

Can I shorten previous to one liner:

delete new Valuable();

Answer 1

If your constructor or destructor has observable behavior, the compiler is not allowed to optimize it out. So there's no need to do anything tricky.