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

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