error: constant of non-structural type `&[B]` in a pattern
  --> $DIR/issue-61188-match-slice-forbidden-without-eq.rs:15:9
   |
LL | struct B(i32);
   | -------- must be annotated with `#[derive(PartialEq)]` to be usable in patterns
LL |
LL | const A: &[B] = &[];
   | ------------- constant defined here
...
LL |         A => (),
   |         ^ constant of non-structural type
   |
   = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralPartialEq.html for details

error: aborting due to 1 previous error