src/test/ui/borrowck/borrowck-issue-14498.rs

   1 // This tests that we can't modify Box<&mut T> contents while they
   2 // are borrowed (#14498).
   3 //
   4 // Also includes tests of the errors reported when the Box in question
   5 // is immutable (#14270).
   6
   7
   8
   9 struct A { a: isize }
  10 struct B<'a> { a: Box<&'a mut isize> }
  11
  12 fn indirect_write_to_imm_box() {
  13     let mut x: isize = 1;
  14     let y: Box<_> = Box::new(&mut x);
  15     let p = &y;
  16     ***p = 2; //~ ERROR cannot assign to `***p`
  17     drop(p);
  18 }
  19
  20 fn borrow_in_var_from_var() {
  21     let mut x: isize = 1;
  22     let mut y: Box<_> = Box::new(&mut x);
  23     let p = &y;
  24     let q = &***p;
  25     **y = 2; //~ ERROR cannot assign to `**y` because it is borrowed
  26     drop(p);
  27     drop(q);
  28 }
  29
  30 fn borrow_in_var_from_var_via_imm_box() {
  31     let mut x: isize = 1;
  32     let y: Box<_> = Box::new(&mut x);
  33     let p = &y;
  34     let q = &***p;
  35     **y = 2; //~ ERROR cannot assign to `**y` because it is borrowed
  36     drop(p);
  37     drop(q);
  38 }
  39
  40 fn borrow_in_var_from_field() {
  41     let mut x = A { a: 1 };
  42     let mut y: Box<_> = Box::new(&mut x.a);
  43     let p = &y;
  44     let q = &***p;
  45     **y = 2; //~ ERROR cannot assign to `**y` because it is borrowed
  46     drop(p);
  47     drop(q);
  48 }
  49
  50 fn borrow_in_var_from_field_via_imm_box() {
  51     let mut x = A { a: 1 };
  52     let y: Box<_> = Box::new(&mut x.a);
  53     let p = &y;
  54     let q = &***p;
  55     **y = 2; //~ ERROR cannot assign to `**y` because it is borrowed
  56     drop(p);
  57     drop(q);
  58 }
  59
  60 fn borrow_in_field_from_var() {
  61     let mut x: isize = 1;
  62     let mut y = B { a: Box::new(&mut x) };
  63     let p = &y.a;
  64     let q = &***p;
  65     **y.a = 2; //~ ERROR cannot assign to `**y.a` because it is borrowed
  66     drop(p);
  67     drop(q);
  68 }
  69
  70 fn borrow_in_field_from_var_via_imm_box() {
  71     let mut x: isize = 1;
  72     let y = B { a: Box::new(&mut x) };
  73     let p = &y.a;
  74     let q = &***p;
  75     **y.a = 2; //~ ERROR cannot assign to `**y.a` because it is borrowed
  76     drop(p);
  77     drop(q);
  78 }
  79
  80 fn borrow_in_field_from_field() {
  81     let mut x = A { a: 1 };
  82     let mut y = B { a: Box::new(&mut x.a) };
  83     let p = &y.a;
  84     let q = &***p;
  85     **y.a = 2; //~ ERROR cannot assign to `**y.a` because it is borrowed
  86     drop(p);
  87     drop(q);
  88 }
  89
  90 fn borrow_in_field_from_field_via_imm_box() {
  91     let mut x = A { a: 1 };
  92     let y = B { a: Box::new(&mut x.a) };
  93     let p = &y.a;
  94     let q = &***p;
  95     **y.a = 2; //~ ERROR cannot assign to `**y.a` because it is borrowed
  96     drop(p);
  97     drop(q);
  98 }
  99
 100 fn main() {
 101     indirect_write_to_imm_box();
 102     borrow_in_var_from_var();
 103     borrow_in_var_from_var_via_imm_box();
 104     borrow_in_var_from_field();
 105     borrow_in_var_from_field_via_imm_box();
 106     borrow_in_field_from_var();
 107     borrow_in_field_from_var_via_imm_box();
 108     borrow_in_field_from_field();
 109     borrow_in_field_from_field_via_imm_box();
 110 }