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// 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);
}
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