declare_clippy_lint! {
/// **What it does:** Checks for `enum`s with no variants.
///
+ /// As of this writing, the `never_type` is still a
+ /// nightly-only experimental API. Therefore, this lint is only triggered
+ /// if the `never_type` is enabled.
+ ///
/// **Why is this bad?** If you want to introduce a type which
- /// can't be instantiated, you should use `!` (the never type),
+ /// can't be instantiated, you should use `!` (the primitive type "never"),
/// or a wrapper around it, because `!` has more extensive
/// compiler support (type inference, etc...) and wrappers
/// around it are the conventional way to define an uninhabited type.
declare_lint_pass!(EmptyEnum => [EMPTY_ENUM]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EmptyEnum {
- fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &Item<'_>) {
- let did = cx.tcx.hir().local_def_id(item.hir_id);
+impl<'tcx> LateLintPass<'tcx> for EmptyEnum {
+ fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
+ // Only suggest the `never_type` if the feature is enabled
+ if !cx.tcx.features().never_type {
+ return;
+ }
+
if let ItemKind::Enum(..) = item.kind {
- let ty = cx.tcx.type_of(did);
+ let ty = cx.tcx.type_of(item.def_id);
let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
if adt.variants.is_empty() {
span_lint_and_help(