src/test/run-pass/dst-deref-mut.rs

   1 // Copyright 2014 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 // Test that a custom deref with a fat pointer return type does not ICE
  12
  13 // pretty-expanded FIXME #23616
  14
  15 use std::ops::{Deref, DerefMut};
  16
  17 pub struct Arr {
  18     ptr: Box<[usize]>
  19 }
  20
  21 impl Deref for Arr {
  22     type Target = [usize];
  23
  24     fn deref(&self) -> &[usize] {
  25         panic!();
  26     }
  27 }
  28
  29 impl DerefMut for Arr {
  30     fn deref_mut(&mut self) -> &mut [usize] {
  31         &mut *self.ptr
  32     }
  33 }
  34
  35 pub fn foo(arr: &mut Arr) {
  36     let x: &mut [usize] = &mut **arr;
  37     assert!(x[0] == 1);
  38     assert!(x[1] == 2);
  39     assert!(x[2] == 3);
  40 }
  41
  42 fn main() {
  43     // FIXME (#22405): Replace `Box::new` with `box` here when/if possible.
  44     let mut a = Arr { ptr: Box::new([1, 2, 3]) };
  45     foo(&mut a);
  46 }