// 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); }