error[E0507]: cannot move out of index of `Vec<(String, String)>`
  --> $DIR/issue-40402-2.rs:5:18
   |
LL |     let (a, b) = x[0];
   |          -  -    ^^^^ help: consider borrowing here: `&x[0]`
   |          |  |
   |          |  ...and here
   |          data moved here
   |
   = note: move occurs because these variables have types that don't implement the `Copy` trait

error: aborting due to previous error

For more information about this error, try `rustc --explain E0507`.