> deleting on CM exit when used as a CM, and no change in behaviour 
> otherwise (me, Zachary, Ethan, Jason and Steve). Steve also wants
> O_TEMPORARY to be removed, which doesn't seem controversial among
> this group of people.

Removing O_TEMPORARY is not an afterthought here. It is the core of this issue. The O_TEMPORARY flag MUST NOT be used if the goal is to make NamedTemporaryFile() "particularly useful on Windows". A file that's opened with DELETE access cannot be reopened in most cases, because most opens do not share delete access, but it also can't be closed to allow it to be reopened because the OS will delete it.

I replied twice that I thought using the CM exit instead of O_TEMPORARY is okay for NamedTemporaryFile() -- but only if a separate implementation of TemporaryFile() that uses O_TEMPORARY is added at the same time. I want guaranteed cleanup for TemporaryFile() since it's not intended to be reopened.