| // Copyright 2015 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. |
| |
| // Demonstrate the use of the unguarded escape hatch with a lifetime param |
| // to assert that destructor will not access any dead data. |
| // |
| // Compare with compile-fail/issue28498-reject-lifetime-param.rs |
| |
| #![feature(dropck_parametricity)] |
| |
| #[derive(Debug)] |
| struct ScribbleOnDrop(String); |
| |
| impl Drop for ScribbleOnDrop { |
| fn drop(&mut self) { |
| self.0 = format!("DROPPED"); |
| } |
| } |
| |
| struct Foo<'a>(u32, &'a ScribbleOnDrop); |
| |
| impl<'a> Drop for Foo<'a> { |
| #[unsafe_destructor_blind_to_params] |
| fn drop(&mut self) { |
| // Use of `unsafe_destructor_blind_to_params` is sound, |
| // because destructor never accesses `self.1`. |
| println!("Dropping Foo({}, _)", self.0); |
| } |
| } |
| |
| fn main() { |
| let (last_dropped, foo0); |
| let (foo1, first_dropped); |
| |
| last_dropped = ScribbleOnDrop(format!("last")); |
| first_dropped = ScribbleOnDrop(format!("first")); |
| foo0 = Foo(0, &last_dropped); |
| foo1 = Foo(1, &first_dropped); |
| |
| println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1); |
| } |