src/test/ui/nll/enum-drop-access.rs

   1 #![feature(nll)]
   2
   3 enum DropOption<T> {
   4     Some(T),
   5     None,
   6 }
   7
   8 impl<T> Drop for DropOption<T> {
   9     fn drop(&mut self) {}
  10 }
  11
  12 // Dropping opt could access the value behind the reference,
  13 fn drop_enum(opt: DropOption<&mut i32>) -> Option<&mut i32> {
  14     match opt {
  15         DropOption::Some(&mut ref mut r) => { //~ ERROR
  16             Some(r)
  17         },
  18         DropOption::None => None,
  19     }
  20 }
  21
  22 fn optional_drop_enum(opt: Option<DropOption<&mut i32>>) -> Option<&mut i32> {
  23     match opt {
  24         Some(DropOption::Some(&mut ref mut r)) => { //~ ERROR
  25             Some(r)
  26         },
  27         Some(DropOption::None) | None => None,
  28     }
  29 }
  30
  31 // Ok, dropping opt doesn't access the reference
  32 fn optional_tuple(opt: Option<(&mut i32, String)>) -> Option<&mut i32> {
  33     match opt {
  34         Some((&mut ref mut r, _)) => {
  35             Some(r)
  36         },
  37         None => None,
  38     }
  39 }
  40
  41 // Ok, dropping res doesn't access the Ok case.
  42 fn different_variants(res: Result<&mut i32, String>) -> Option<&mut i32> {
  43     match res {
  44         Ok(&mut ref mut r) => {
  45             Some(r)
  46         },
  47         Err(_) => None,
  48     }
  49 }
  50
  51 fn main() {}