https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201
--- Comment #25 from Sean <brlcad at mac dot com> --- Ah, that makes sense, thank you Richard. I didn't pay as close attention to the actual swap() code and casting going on there. Apparently unrelated, but perhaps worth noting the reason this come up on my radar is because the latest compilers now also issue a warning on the subtraction: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
