src/test/ui/issues/issue-39367.rs

   1 // run-pass
   2 // revisions: mir thir
   3 // [thir]compile-flags: -Zthir-unsafeck
   4
   5 use std::ops::Deref;
   6
   7 struct ArenaSet<U: Deref, V=<U as Deref>::Target>(U, &'static V)
   8     where V: 'static + ?Sized;
   9
  10 static Z: [u8; 4] = [1,2,3,4];
  11
  12 fn arena() -> &'static ArenaSet<Vec<u8>> {
  13     fn __static_ref_initialize() -> ArenaSet<Vec<u8>> {
  14         ArenaSet(vec![], &Z)
  15     }
  16     unsafe {
  17         use std::sync::Once;
  18         fn require_sync<T: Sync>(_: &T) { }
  19         unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
  20             use std::mem::transmute;
  21             static mut DATA: *const ArenaSet<Vec<u8>> = std::ptr::null_mut();
  22
  23             static mut ONCE: Once = Once::new();
  24             ONCE.call_once(|| {
  25                 DATA = transmute
  26                     ::<Box<ArenaSet<Vec<u8>>>, *const ArenaSet<Vec<u8>>>
  27                     (Box::new(__static_ref_initialize()));
  28             });
  29
  30             &*DATA
  31         }
  32         let static_ref = __stability();
  33         require_sync(static_ref);
  34         static_ref
  35     }
  36 }
  37
  38 fn main() {
  39     let &ArenaSet(ref u, v) = arena();
  40     assert!(u.is_empty());
  41     assert_eq!(v, Z);
  42 }