error[E0277]: the type `std::cell::UnsafeCell<i32>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
  --> $DIR/interior-mutability.rs:5:5
   |
LL |     catch_unwind(|| { x.set(23); });
   |     ^^^^^^^^^^^^ `std::cell::UnsafeCell<i32>` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary
   |
   = help: within `std::cell::Cell<i32>`, the trait `std::panic::RefUnwindSafe` is not implemented for `std::cell::UnsafeCell<i32>`
   = note: required because it appears within the type `std::cell::Cell<i32>`
   = note: required because of the requirements on the impl of `std::panic::UnwindSafe` for `&std::cell::Cell<i32>`
   = note: required because it appears within the type `[closure@$DIR/interior-mutability.rs:5:18: 5:35 x:&std::cell::Cell<i32>]`
   = note: required by `std::panic::catch_unwind`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.