| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| #![feature(untagged_unions)] |
| |
| use std::cell::Cell; |
| use std::ops::Deref; |
| use std::mem::ManuallyDrop; |
| |
| union Wrap<T> { x: ManuallyDrop<T> } |
| |
| impl<T> Drop for Wrap<T> { |
| fn drop(&mut self) { |
| unsafe { std::ptr::drop_in_place(&mut *self.x as *mut T); } |
| } |
| } |
| |
| impl<T> Wrap<T> { |
| fn new(x: T) -> Self { |
| Wrap { x: ManuallyDrop::new(x) } |
| } |
| } |
| |
| impl<T> Deref for Wrap<T> { |
| type Target = T; |
| #[inline] |
| fn deref(&self) -> &Self::Target { |
| unsafe { |
| &self.x |
| } |
| } |
| } |
| |
| struct C<'a>(Cell<Option<&'a C<'a>>>); |
| |
| impl<'a> Drop for C<'a> { |
| fn drop(&mut self) {} |
| } |
| |
| fn main() { |
| let v : Wrap<C> = Wrap::new(C(Cell::new(None))); |
| v.0.set(Some(&v)); //~ ERROR: `v` does not live long enough |
| } |