> How would that work? You want a nontail keyword to indicate that intent explicitly?

Either that, or to not have TCO applied if I don't set a keyword (which I'd prefer).

> I guess I could imagine a scenario where you want to de-optimize a TCO into a non-TC... but I mean... that's got to be rare enough to just not bother with?

Sometimes I know that a given function will eventually need to be non-TC, in which case I want a way to make it non-TCO now. More commonly a junior team member just hasn't thought about TC-ness at all, in which case I'd rather the function not be TCOed and fail-fast than be TCOed until it isn't.

> EDIT: Also, this is the exact opposite of your comment which I replied to.

No it isn't. It's the detail of how it happens. If you use Scala at scale with a team that includes non-experts it will happen to you.