va_list isn't quite enough to get you theoretically infinitely-addressable memory. A va_list is a blittable struct [1], and thus has a size, which means you can

va_list isn't quite enough to get you theoretically infinitely-addressable memory. A va_list is a blittable struct [1], and thus has a size, which means you can only have a finite number of them in your program. And the only way to push onto a va_list is to create a new one (by variadic function call), which also implies a maximum bound on the size of a va_list even with pointerless pointers. [1] Whether that copy is meaningfully usable is a different matter, which is why va_copy exists.