warning: the feature `const_generics` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/forbid-non-structural_match-types.rs:1:12
   |
LL | #![feature(const_generics)]
   |            ^^^^^^^^^^^^^^
   |
   = note: `#[warn(incomplete_features)]` on by default
   = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information

error[E0741]: `C` must be annotated with `#[derive(PartialEq, Eq)]` to be used as the type of a const parameter
  --> $DIR/forbid-non-structural_match-types.rs:11:19
   |
LL | struct D<const X: C>;
   |                   ^ `C` doesn't derive both `PartialEq` and `Eq`

error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0741`.