1 // Check that an arena (TypedArena) cannot carry elements whose drop
2 // methods might access borrowed data of lifetime that does not
3 // strictly outlive the arena itself.
5 // Compare against run-pass/dropck_tarena_sound_drop.rs, which shows a
6 // similar setup, but loosens `f` so that the struct `C<'a>` can be
7 // fed a lifetime longer than that of the arena.
9 // (Also compare against dropck_tarena_cycle_checked.rs, from which
10 // this was reduced to better understand its error message.)
12 #![feature(rustc_private)]
14 extern crate rustc_arena;
16 use rustc_arena::TypedArena;
18 trait HasId { fn count(&self) -> usize; }
20 struct CheckId<T:HasId> { v: T }
22 // In the code below, the impl of HasId for `&'a usize` does not
23 // actually access the borrowed data, but the point is that the
24 // interface to CheckId does not (and cannot) know that, and therefore
25 // when encountering a value V of type CheckId<S>, we must
26 // conservatively force the type S to strictly outlive V.
27 impl<T:HasId> Drop for CheckId<T> {
29 assert!(self.v.count() > 0);
33 struct C<'a> { v: CheckId<&'a usize>, }
35 impl<'a> HasId for &'a usize { fn count(&self) -> usize { 1 } }
37 fn f<'a>(_arena: &'a TypedArena<C<'a>>) {}
40 let arena: TypedArena<C> = TypedArena::default();
42 } //~^ ERROR `arena` does not live long enough