> 0x7ffffffffffffffff. The typical argument is that such a value would be “pathological”. Not only is this argument incorrect, it’s even more dangerous which we will see later.

The only later thing I see that's somewhat relevant to that appears to be dealing with 32 bit overflow? That doesn't prove the argument incorrect.

No current OS I'm aware of lets you have a size_t that goes over 2^63. I doubt any OS will ever allow it. It makes things easier if virtual memory is capped to 2^62 or so, and if anyone really ends up with a use case for more I expect them to switch to 128 bit numbers.