[mining]

> But it doesn't give one when the cast is in a loop condition. That is weird.

I believe that the justification for that is that you'll often want to do e.g.

    while (node) {
      node.val += 3;
      node = node->next;
    }

Implicit conversion of a type into a bool is pretty useful here, or for e.g.

    while (std::cin >> x >> y) { ... }