src/test/ui/consts/const_in_pattern/custom-eq-branch-warn.rs

   1 // check-pass
   2
   3 struct CustomEq;
   4
   5 impl Eq for CustomEq {}
   6 impl PartialEq for CustomEq {
   7     fn eq(&self, _: &Self) -> bool {
   8         false
   9     }
  10 }
  11
  12 #[derive(PartialEq, Eq)]
  13 enum Foo {
  14     Bar,
  15     Baz,
  16     Qux(CustomEq),
  17 }
  18
  19 // We know that `BAR_BAZ` will always be `Foo::Bar` and thus eligible for structural matching, but
  20 // dataflow will be more conservative.
  21 const BAR_BAZ: Foo = if 42 == 42 {
  22     Foo::Bar
  23 } else {
  24     Foo::Qux(CustomEq)
  25 };
  26
  27 fn main() {
  28     match Foo::Qux(CustomEq) {
  29         BAR_BAZ => panic!(),
  30         //~^ WARN must be annotated with `#[derive(PartialEq, Eq)]`
  31         //~| WARN this was previously accepted
  32         //~| NOTE see issue #73448
  33         //~| NOTE `#[warn(nontrivial_structural_match)]` on by default
  34         _ => {}
  35     }
  36 }