src/test/ui/const-generics/forbid-non-structural_match-types.rs

#![feature(const_generics)]
//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash

#[derive(PartialEq, Eq)]
struct A;

struct B<const X: A>; // ok

struct C;

struct D<const X: C>; //~ ERROR the types of const generic parameters must derive

fn main() {}