[x-yl]

Are you suggesting Rust should automatically insert the borrow annotation because it is able to see that a borrow is sufficient? That would be quite unintuitive and make it ambiguous whether a for loop is borrowing or consuming the iterator without reviewing the body. I'd strongly argue that it should unambiguously do either one or the other and not try and read the author's mind.

[59nadir]

Yes, I'm suggesting it should do the right thing for the code the loop is actually trying to execute. I personally think this is exactly what Rust and its users have signed up for. I might be mistaken about that, but I think it's in line with the more general view that Rust is attempting to be as close as it can get to a language that reads like it has a garbage collector without having one.

[DougBTX]

> the more general view that Rust is attempting to be as close as it can get to a language that reads like it has a garbage collector without having one.

I've used Rust a fair amount, and I've never seen that expressed as a goal.

A couple of general principles followed by Rust are to prefer explicit code over implicit conversions and to support local reasoning. Those are both present here: the borrow needs to be made explicitly, rather than implicitly based on code later on.

[Klonoar]

This is not at all what we signed up for. The explicit-ness is the point.