tests/ui/borrowck/borrowck-anon-fields-variant.rs

   1 enum Foo {
   2     X, Y(usize, usize)
   3 }
   4
   5 fn distinct_variant() {
   6     let mut y = Foo::Y(1, 2);
   7
   8     let a = match y {
   9       Foo::Y(ref mut a, _) => a,
  10       Foo::X => panic!()
  11     };
  12
  13     // While `a` and `b` are disjoint, borrowck doesn't know that `a` is not
  14     // also used for the discriminant of `Foo`, which it would be if `a` was a
  15     // reference.
  16     let b = match y {
  17       //~^ ERROR cannot use `y`
  18       Foo::Y(_, ref mut b) => b,
  19       Foo::X => panic!()
  20     };
  21
  22     *a += 1;
  23     *b += 1;
  24 }
  25
  26 fn same_variant() {
  27     let mut y = Foo::Y(1, 2);
  28
  29     let a = match y {
  30       Foo::Y(ref mut a, _) => a,
  31       Foo::X => panic!()
  32     };
  33
  34     let b = match y {
  35       //~^ ERROR cannot use `y`
  36       Foo::Y(ref mut b, _) => b,
  37       //~^ ERROR cannot borrow `y.0` as mutable
  38       Foo::X => panic!()
  39     };
  40
  41     *a += 1;
  42     *b += 1;
  43 }
  44
  45 fn main() {
  46 }