Why is there a performance warning on cast pointer to bool?

Question

Extends.

I thought I was being cool when I did something like:

bool hasParent()
{
  return this->parentNode ;
}

Even with a (bool) cast, the

Answer 1

Why is that a performance warning?

The compiler is turning this:

bool hasParent()
{
  return this->parentNode;
}

into:

bool hasParent()
{
  return this->parentNode != 0;
}

This takes about one clock cycle more than you might expect from looking at the code. It's an insignificant performance difference.

I think it's better to write out the != 0 explicitly anyway, as it makes the code clearer as well as silencing the warning.