src/test/ui/nll/drop-no-may-dangle.rs

   1 // Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Basic test for liveness constraints: the region (`R1`) that appears
  12 // in the type of `p` must include everything until `p` is dropped
  13 // because of destructor. (Note that the stderr also identifies this
  14 // destructor in the error message.)
  15
  16 // compile-flags:-Zborrowck=mir
  17
  18 #![allow(warnings)]
  19 #![feature(dropck_eyepatch)]
  20
  21 fn use_x(_: usize) -> bool { true }
  22
  23 fn main() {
  24     let mut v = [1, 2, 3];
  25     let p: WrapMayNotDangle<&usize> = WrapMayNotDangle { value: &v[0] };
  26     if true {
  27         use_x(*p.value);
  28     } else {
  29         use_x(22);
  30         v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
  31     }
  32
  33     v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
  34 }
  35
  36 struct WrapMayNotDangle<T> {
  37     value: T
  38 }
  39
  40 impl<T> Drop for WrapMayNotDangle<T> {
  41     fn drop(&mut self) { }
  42 }