The thing that has always disturbed me about O_DIRECT is that the whole
interface is just stupid, and was probably designed by a deranged monkey
on some serious mind-controlling substances [*].
So I'm going to have a HARD REQUIREMENT that any compiler complaints
need to be really really sane. They need to detect when people do
things like this on purpose, and they need to SHUT THE ^&% UP about
the fact that wrap-around happens.
Any tool that is so stupid as to complain about wrap-around in the
above is a BROKEN TOOL THAT NEEDS TO BE IGNORED.