error[E0070]: invalid left-hand side of assignment
  --> $DIR/issue-93486.rs:3:36
   |
LL |         vec![].last_mut().unwrap() = 3_u8;
   |         -------------------------- ^
   |         |
   |         cannot assign to this expression

error: aborting due to previous error

For more information about this error, try `rustc --explain E0070`.