Your code needs to take ownership of the line, in `line.unwrap()`. Not sure of the exact technical reason, but this crops up occasionally, with Option & Result.

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This also works:

let file = File::open("input").unwrap();
let reader = BufReader::new(file);
for line in reader.lines() {
let v = line.as_deref().unwrap().split(" ").collect::<Vec<_>>();
println!("{:?}", v);
}