yeah you should explicitly calculate the direction components using a reciprocal (e.g. 1/ray.dir.x) to avoid NaN and also get ±∞ for the 0 case

this technique is mentioned in "An Efficient and Robust Ray–Box Intersection Algorithm": people.csail.mit.edu/amy/papers/b...

You need to use the newer style string literals with the 's' suffix after the quotes:

en.cppreference.com/w/cpp/string...

So something like:

using namespace std::literals;

"resource size is"s + std::to_string(x)