3 fn require_sync<T: Sync>() {}
4 //~^ NOTE required by this bound in `require_sync`
5 //~| NOTE required by a bound in `require_sync`
8 require_sync::<std::cell::RefCell<()>>();
9 //~^ ERROR `RefCell<()>` cannot be shared between threads safely
10 //~| NOTE `RefCell<()>` cannot be shared between threads safely
11 //~| NOTE use `std::sync::RwLock` instead