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//@ run-pass
#![allow(unknown_lints)]
// Check that an arena (TypedArena) can carry elements whose drop
// methods might access borrowed data, as long as the borrowed data
// has lifetime that strictly outlives the arena itself.
//
// Compare against ui-fulldeps/dropck-tarena-unsound-drop.rs, which
// shows a similar setup, but restricts `f` so that the struct `C<'a>`
// is force-fed a lifetime equal to that of the borrowed arena.
#![allow(unstable)]
#![feature(rustc_private)]
extern crate rustc_arena;
// Necessary to pull in object code as the rest of the rustc crates are shipped only as rmeta
// files.
#[allow(unused_extern_crates)]
extern crate rustc_driver;
use rustc_arena::TypedArena;
trait HasId { fn count(&self) -> usize; }
struct CheckId<T:HasId> { v: T }
// In the code below, the impl of HasId for `&'a usize` does not
// actually access the borrowed data, but the point is that the
// interface to CheckId does not (and cannot) know that, and therefore
// when encountering a value V of type CheckId<S>, we must
// conservatively force the type S to strictly outlive V.
impl<T:HasId> Drop for CheckId<T> {
fn drop(&mut self) {
assert!(self.v.count() > 0);
}
}
struct C<'a> { _v: CheckId<&'a usize>, }
impl<'a> HasId for &'a usize { fn count(&self) -> usize { 1 } }
fn f<'a, 'b>(_arena: &'a TypedArena<C<'b>>) {}
fn main() {
let arena: TypedArena<C> = TypedArena::default();
f(&arena);
}
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