src/test/compile-fail/borrowck-borrow-overloaded-auto-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 how overloaded deref interacts with borrows when DerefMut
  12 // is implemented.
  13
  14 use std::ops::{Deref, DerefMut};
  15
  16 struct Own<T> {
  17     value: *mut T
  18 }
  19
  20 impl<T> Deref for Own<T> {
  21     type Target = T;
  22
  23     fn deref(&self) -> &T {
  24         unsafe { &*self.value }
  25     }
  26 }
  27
  28 impl<T> DerefMut for Own<T> {
  29     fn deref_mut(&mut self) -> &mut T {
  30         unsafe { &mut *self.value }
  31     }
  32 }
  33
  34 struct Point {
  35     x: isize,
  36     y: isize
  37 }
  38
  39 impl Point {
  40     fn get(&self) -> (isize, isize) {
  41         (self.x, self.y)
  42     }
  43
  44     fn set(&mut self, x: isize, y: isize) {
  45         self.x = x;
  46         self.y = y;
  47     }
  48
  49     fn x_ref(&self) -> &isize {
  50         &self.x
  51     }
  52
  53     fn y_mut(&mut self) -> &mut isize {
  54         &mut self.y
  55     }
  56 }
  57
  58 fn deref_imm_field(x: Own<Point>) {
  59     let __isize = &x.y;
  60 }
  61
  62 fn deref_mut_field1(x: Own<Point>) {
  63     let __isize = &mut x.y; //~ ERROR cannot borrow
  64 }
  65
  66 fn deref_mut_field2(mut x: Own<Point>) {
  67     let __isize = &mut x.y;
  68 }
  69
  70 fn deref_extend_field(x: &Own<Point>) -> &isize {
  71     &x.y
  72 }
  73
  74 fn deref_extend_mut_field1(x: &Own<Point>) -> &mut isize {
  75     &mut x.y //~ ERROR cannot borrow
  76 }
  77
  78 fn deref_extend_mut_field2(x: &mut Own<Point>) -> &mut isize {
  79     &mut x.y
  80 }
  81
  82 fn deref_extend_mut_field3(x: &mut Own<Point>) {
  83     // Hmm, this is unfortunate, because with box it would work,
  84     // but it's presently the expected outcome. See `deref_extend_mut_field4`
  85     // for the workaround.
  86
  87     let _x = &mut x.x;
  88     let _y = &mut x.y; //~ ERROR cannot borrow
  89 }
  90
  91 fn deref_extend_mut_field4<'a>(x: &'a mut Own<Point>) {
  92     let p = &mut **x;
  93     let _x = &mut p.x;
  94     let _y = &mut p.y;
  95 }
  96
  97 fn assign_field1<'a>(x: Own<Point>) {
  98     x.y = 3; //~ ERROR cannot borrow
  99 }
 100
 101 fn assign_field2<'a>(x: &'a Own<Point>) {
 102     x.y = 3; //~ ERROR cannot assign
 103 }
 104
 105 fn assign_field3<'a>(x: &'a mut Own<Point>) {
 106     x.y = 3;
 107 }
 108
 109 fn assign_field4<'a>(x: &'a mut Own<Point>) {
 110     let _p: &mut Point = &mut **x;
 111     x.y = 3; //~ ERROR cannot borrow
 112 }
 113
 114 fn deref_imm_method(x: Own<Point>) {
 115     let __isize = x.get();
 116 }
 117
 118 fn deref_mut_method1(x: Own<Point>) {
 119     x.set(0, 0); //~ ERROR cannot borrow
 120 }
 121
 122 fn deref_mut_method2(mut x: Own<Point>) {
 123     x.set(0, 0);
 124 }
 125
 126 fn deref_extend_method(x: &Own<Point>) -> &isize {
 127     x.x_ref()
 128 }
 129
 130 fn deref_extend_mut_method1(x: &Own<Point>) -> &mut isize {
 131     x.y_mut() //~ ERROR cannot borrow
 132 }
 133
 134 fn deref_extend_mut_method2(x: &mut Own<Point>) -> &mut isize {
 135     x.y_mut()
 136 }
 137
 138 fn assign_method1<'a>(x: Own<Point>) {
 139     *x.y_mut() = 3; //~ ERROR cannot borrow
 140 }
 141
 142 fn assign_method2<'a>(x: &'a Own<Point>) {
 143     *x.y_mut() = 3; //~ ERROR cannot borrow
 144 }
 145
 146 fn assign_method3<'a>(x: &'a mut Own<Point>) {
 147     *x.y_mut() = 3;
 148 }
 149
 150 pub fn main() {}