error[E0382]: use of moved value
  --> $DIR/track2.rs:LL:CC
   |
LL |     let _moved @ _from = String::from("foo");
   |         ^^^^^^   -----   ------------------- move occurs because value has type `String`, which does not implement the `Copy` trait
   |         |        |
   |         |        value moved here
   |         value used here after move
-Ztrack-diagnostics: created at compiler/rustc_borrowck/src/borrowck_errors.rs:LL:CC
   |
help: borrow this binding in the pattern to avoid moving the value
   |
LL |     let ref _moved @ ref _from = String::from("foo");
   |         +++          +++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0382`.