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`.