clean-up a bit

clippy_lints/src/empty_enum.rs

@@ -62,11 +62,10 @@
 
 impl LateLintPass<'_> for EmptyEnum {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
-        if let ItemKind::Enum(..) = item.kind
+        if let ItemKind::Enum(.., def) = item.kind
+            && def.variants.is_empty()
             // Only suggest the `never_type` if the feature is enabled
             && cx.tcx.features().never_type()
-            && let Some(adt) = cx.tcx.type_of(item.owner_id).instantiate_identity().ty_adt_def()
-            && adt.variants().is_empty()
         {
             span_lint_and_help(
                 cx,

tests/ui/empty_enum.rs

@@ -1,7 +1,7 @@
-#![allow(dead_code)]
 #![warn(clippy::empty_enum)]
 // Enable never type to test empty enum lint
 #![feature(never_type)]
+
 enum Empty {}
 //~^ empty_enum
 

tests/ui/empty_enum_without_never_type.rs

@@ -1,6 +1,5 @@
 //@ check-pass
 
-#![allow(dead_code)]
 #![warn(clippy::empty_enum)]
 
 // `never_type` is not enabled; this test has no stderr file