error[E0499]: cannot borrow `*r` as mutable more than once at a time
--> tests/ui/column_borrow.rs:9:29
|
8 | let col1 = &mut r[0];
| - first mutable borrow occurs here
9 | let col2 = &mut r[1];
| ^ second mutable borrow occurs here
10 | assert_ne!(col1.get_str()?, col2.get_str()?);
| ---- first borrow later used here