src/test/ui/typeck/typeck-unsafe-always-share.rs

   1 // Verify that UnsafeCell is *always* !Sync regardless if `T` is sync.
   2
   3 #![feature(negative_impls)]
   4
   5 use std::cell::UnsafeCell;
   6 use std::marker::Sync;
   7
   8 struct MySync<T> {
   9     u: UnsafeCell<T>
  10 }
  11
  12 struct NoSync;
  13 impl !Sync for NoSync {}
  14
  15 fn test<T: Sync>(s: T) {}
  16
  17 fn main() {
  18     let us = UnsafeCell::new(MySync{u: UnsafeCell::new(0)});
  19     test(us);
  20     //~^ ERROR `std::cell::UnsafeCell<MySync<{integer}>>` cannot be shared between threads safely
  21
  22     let uns = UnsafeCell::new(NoSync);
  23     test(uns);
  24     //~^ ERROR `std::cell::UnsafeCell<NoSync>` cannot be shared between threads safely [E0277]
  25
  26     let ms = MySync{u: uns};
  27     test(ms);
  28     //~^ ERROR `std::cell::UnsafeCell<NoSync>` cannot be shared between threads safely [E0277]
  29
  30     test(NoSync);
  31     //~^ ERROR `NoSync` cannot be shared between threads safely [E0277]
  32 }