error[E0716]: temporary value dropped while borrowed
  --> $DIR/borrowck-let-suggestion.rs:2:17
   |
LL |     let mut x = vec![1].iter();
   |                 ^^^^^^^       - temporary value is freed at the end of this statement
   |                 |
   |                 creates a temporary which is freed while still in use
LL |
LL |     x.use_mut();
   |     - borrow later used here
   |
   = note: consider using a `let` binding to create a longer lived value
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0716`.