1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Check that a arena (TypedArena) can carry elements whose drop
12 // methods might access borrowed data, as long as the borrowed data
13 // has lifetime that strictly outlives the arena itself.
15 // Compare against compile-fail/dropck_tarena_unsound_drop.rs, which
16 // shows a similar setup, but restricts `f` so that the struct `C<'a>`
17 // is force-fed a lifetime equal to that of the borrowed arena.
20 #![feature(unsafe_destructor, rustc_private)]
24 use arena::TypedArena;
26 trait HasId { fn count(&self) -> usize; }
28 struct CheckId<T:HasId> { v: T }
30 // In the code below, the impl of HasId for `&'a usize` does not
31 // actually access the borrowed data, but the point is that the
32 // interface to CheckId does not (and cannot) know that, and therefore
33 // when encountering the a value V of type CheckId<S>, we must
34 // conservatively force the type S to strictly outlive V.
36 impl<T:HasId> Drop for CheckId<T> {
38 assert!(self.v.count() > 0);
42 struct C<'a> { _v: CheckId<&'a usize>, }
44 impl<'a> HasId for &'a usize { fn count(&self) -> usize { 1 } }
46 fn f<'a, 'b>(_arena: &'a TypedArena<C<'b>>) {}
49 let arena: TypedArena<C> = TypedArena::new();