src/test/ui/borrowck/borrowck-scope-of-deref-issue-4666.rs

   1 // run-pass
   2 // Tests that the scope of the pointer returned from `get()` is
   3 // limited to the deref operation itself, and does not infect the
   4 // block as a whole.
   5
   6
   7 struct Box {
   8     x: usize
   9 }
  10
  11 impl Box {
  12     fn get(&self) -> &usize {
  13         &self.x
  14     }
  15     fn set(&mut self, x: usize) {
  16         self.x = x;
  17     }
  18 }
  19
  20 fn fun1() {
  21     // in the past, borrow checker behaved differently when
  22     // init and decl of `v` were distinct
  23     let v;
  24     let mut a_box = Box {x: 0};
  25     a_box.set(22);
  26     v = *a_box.get();
  27     a_box.set(v+1);
  28     assert_eq!(23, *a_box.get());
  29 }
  30
  31 fn fun2() {
  32     let mut a_box = Box {x: 0};
  33     a_box.set(22);
  34     let v = *a_box.get();
  35     a_box.set(v+1);
  36     assert_eq!(23, *a_box.get());
  37 }
  38
  39 pub fn main() {
  40     fun1();
  41     fun2();
  42 }