error[E0597]: `c` does not live long enough
  --> $DIR/regionck-unboxed-closure-lifetimes.rs:8:21
   |
LL |         let c = 1;
   |             - binding `c` declared here
LL |         let c_ref = &c;
   |                     ^^ borrowed value does not live long enough
...
LL |     }
   |     - `c` dropped here while still borrowed
LL |     f.use_mut();
   |     - borrow later used here

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0597`.