warning: to use a constant of type `CustomEq` in a pattern, the constant's initializer must be trivial or `CustomEq` must be annotated with `#[derive(PartialEq, Eq)]`
  --> $DIR/custom-eq-branch-warn.rs:29:9
   |
LL |         BAR_BAZ => panic!(),
   |         ^^^^^^^
   |
   = note: `#[warn(nontrivial_structural_match)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #73448 <https://github.com/rust-lang/rust/issues/73448>

warning: 1 warning emitted