warning: to use a constant of type `&[O<B>]` in a pattern, the type must implement `PartialEq`
  --> $DIR/issue-65466.rs:18:9
   |
LL |         C => (),
   |         ^
   |
   = 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 #116122 <https://github.com/rust-lang/rust/issues/116122>
   = note: `#[warn(const_patterns_without_partial_eq)]` on by default

warning: 1 warning emitted

Future incompatibility report: Future breakage diagnostic:
warning: to use a constant of type `&[O<B>]` in a pattern, the type must implement `PartialEq`
  --> $DIR/issue-65466.rs:18:9
   |
LL |         C => (),
   |         ^
   |
   = 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 #116122 <https://github.com/rust-lang/rust/issues/116122>
   = note: `#[warn(const_patterns_without_partial_eq)]` on by default