Oh Windows…
Yeah, I'm definitely not advocating to change OsString or OsStr. Can I ask why the idea of vending a Cow from the platform-neutral API seems to have not been as compelling as I was thinking? That seemed, to me, to be a good solution to the problem. Am I misunderstanding why/when to use Cow?
In any case, is this something that would make sense to try to PR into the standard library? I've read a bit of the contribution guide, and it seems fairly doable.