warning: value assigned to `d` is never read
 --> ownership.rs:2:17
  |
2 |     let mut d = String::from("hello");
  |                 ^^^^^^^^^^^^^^^^^^^^^
  |
  = help: maybe it is overwritten before being read?
  = note: `#[warn(unused_assignments)]` (part of `#[warn(unused)]`) on by default

warning: value assigned to `d` is never read
 --> ownership.rs:2:17
  |
2 |     let mut d = String::from("hello");
  |                 ^^^^^^^^^^^^^^^^^^^^^ this value is reassigned later and never used
3 |     d = String::from("ahoy");
  |         -------------------- `d` is overwritten here before the previous value is read
  |
  = note: `#[warn(unused_assignments)]` (part of `#[warn(unused)]`) on by default