1error[E0596]: cannot borrow `v` as mutable, as it is not declared as mutable
2  --> $DIR/writing-to-immutable-vec.rs:3:5
3   |
4LL |     let v: Vec<isize> = vec![1, 2, 3];
5   |         - help: consider changing this to be mutable: `mut v`
6LL |     v[1] = 4;
7   |     ^ cannot borrow as mutable
8
9error: aborting due to previous error
10
11For more information about this error, try `rustc --explain E0596`.
12