error[E0502]: cannot borrow `p` as mutable because it is also borrowed as immutable
  --> $DIR/borrowck-assign-comp-idx.rs:12:5
   |
LL |     let q: &isize = &p[0];
   |                      - immutable borrow occurs here
LL | 
LL |     p[0] = 5;
   |     ^ mutable borrow occurs here
LL | 
LL |     println!("{}", *q);
   |                    -- immutable borrow later used here

error[E0502]: cannot borrow `p` as mutable because it is also borrowed as immutable
  --> $DIR/borrowck-assign-comp-idx.rs:27:9
   |
LL |     borrow(
   |     ------ immutable borrow later used by call
LL |         &p,
   |         -- immutable borrow occurs here
LL |         || p[0] = 5);
   |         ^^ - second borrow occurs due to use of `p` in closure
   |         |
   |         mutable borrow occurs here

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0502`.