| // Copyright 2012-2016 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. |
| |
| // Basic test for liveness constraints: the region (`R1`) that appears |
| // in the type of `p` includes the points after `&v[0]` up to (but not |
| // including) the call to `use_x`. The `else` branch is not included. |
| |
| // compile-flags:-Zborrowck=mir |
| // compile-pass |
| |
| #![allow(warnings)] |
| #![feature(dropck_eyepatch)] |
| |
| fn use_x(_: usize) -> bool { true } |
| |
| fn main() { |
| let mut v = [1, 2, 3]; |
| let p: WrapMayDangle<& /* R4 */ usize> = WrapMayDangle { value: &v[0] }; |
| if true { |
| // `p` will get dropped at end of this block. However, because of |
| // the `#[may_dangle]` attribute, we do not need to consider R4 |
| // live after this point. |
| use_x(*p.value); |
| } else { |
| v[0] += 1; |
| use_x(22); |
| } |
| |
| v[0] += 1; |
| } |
| |
| struct WrapMayDangle<T> { |
| value: T |
| } |
| |
| unsafe impl<#[may_dangle] T> Drop for WrapMayDangle<T> { |
| fn drop(&mut self) { } |
| } |