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 an arena (TypedArena) cannot carry elements whose drop
12 // methods might access borrowed data of lifetime that does not
13 // strictly outlive the arena itself.
15 // Compare against run-pass/dropck_tarena_sound_drop.rs, which shows a
16 // similar setup, but loosens `f` so that the struct `C<'a>` can be
17 // fed a lifetime longer than that of the arena.
19 // (Also compare against dropck_tarena_cycle_checked.rs, from which
20 // this was reduced to better understand its error message.)
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 a value V of type CheckId<S>, we must
34 // conservatively force the type S to strictly outlive V.
35 impl<T
:HasId
> Drop
for CheckId
<T
> {
37 assert
!(self.v
.count() > 0);
41 struct C
<'a
> { v: CheckId<&'a usize>, }
43 impl<'a
> HasId
for &'a
usize { fn count(&self) -> usize { 1 }
}
45 fn f
<'a
>(_arena
: &'a TypedArena
<C
<'a
>>) {}
48 let arena
: TypedArena
<C
> = TypedArena
::new();
49 f(&arena
); //~ ERROR `arena` does not live long enough