error[E0599]: `usize` is not an iterator --> $DIR/issue-90315.rs:3:26 | LL | for _i in 0..arr.len().rev() { | ^^^ `usize` is not an iterator | = note: the following trait bounds were not satisfied: `usize: Iterator` which is required by `&mut usize: Iterator` error: aborting due to previous error For more information about this error, try `rustc --explain E0599`.