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

   1 // Basic test for liveness constraints: the region (`R1`) that appears
   2 // in the type of `p` must include everything until `p` is dropped
   3 // because of destructor. (Note that the stderr also identifies this
   4 // destructor in the error message.)
   5
   6 #![allow(warnings)]
   7 #![feature(dropck_eyepatch)]
   8
   9 fn use_x(_: usize) -> bool { true }
  10
  11 fn main() {
  12     let mut v = [1, 2, 3];
  13     let p: WrapMayNotDangle<&usize> = WrapMayNotDangle { value: &v[0] };
  14     if true {
  15         use_x(*p.value);
  16     } else {
  17         use_x(22);
  18         v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
  19     }
  20
  21     v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
  22 }
  23
  24 struct WrapMayNotDangle<T> {
  25     value: T
  26 }
  27
  28 impl<T> Drop for WrapMayNotDangle<T> {
  29     fn drop(&mut self) { }
  30 }