warning: the feature `adt_const_params` is incomplete and may not be safe to use and/or cause compiler crashes --> $DIR/issue-80471.rs:1:12 | LL | #![feature(adt_const_params)] | ^^^^^^^^^^^^^^^^ | = note: see issue #95174 for more information = note: `#[warn(incomplete_features)]` on by default error[E0741]: `Nat` must implement `ConstParamTy` to be used as the type of a const generic parameter --> $DIR/issue-80471.rs:10:17 | LL | fn foo() {} | ^^^ | help: add `#[derive(ConstParamTy)]` to the struct | LL + #[derive(ConstParamTy)] LL | enum Nat { | error: aborting due to 1 previous error; 1 warning emitted For more information about this error, try `rustc --explain E0741`.