error[E0277]: `std::rc::Rc<usize>` cannot be sent between threads safely
  --> $DIR/kindck-nonsendable-1.rs:9:5
   |
LL | fn bar<F:FnOnce() + Send>(_: F) { }
   |    ---              ---- required by this bound in `bar`
...
LL |     bar(move|| foo(x));
   |     ^^^ `std::rc::Rc<usize>` cannot be sent between threads safely
   |
   = help: within `[closure@$DIR/kindck-nonsendable-1.rs:9:9: 9:22 x:std::rc::Rc<usize>]`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<usize>`
   = note: required because it appears within the type `[closure@$DIR/kindck-nonsendable-1.rs:9:9: 9:22 x:std::rc::Rc<usize>]`

error: aborting due to previous error

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