Revert "Rollup merge of rust-lang#124460 - long-long-float:show-notice-about-enum-with-debug, r=pnkfelix"

This reverts commit 00e5f58, reversing
changes made to 5a3e2a4.

Author: compiler-errors

compiler/rustc_passes/src/dead.rs

@@ -1011,22 +1011,6 @@ impl<'tcx> DeadVisitor<'tcx> {
         parent_item: Option<LocalDefId>,
         report_on: ReportOn,
     ) {
-        fn get_parent_if_enum_variant<'tcx>(
-            tcx: TyCtxt<'tcx>,
-            may_variant: LocalDefId,
-        ) -> LocalDefId {
-            if let Node::Variant(_) = tcx.hir_node_by_def_id(may_variant)
-                && let Some(enum_did) = tcx.opt_parent(may_variant.to_def_id())
-                && let Some(enum_local_id) = enum_did.as_local()
-                && let Node::Item(item) = tcx.hir_node_by_def_id(enum_local_id)
-                && let ItemKind::Enum(_, _) = item.kind
-            {
-                enum_local_id
-            } else {
-                may_variant
-            }
-        }
-
         let Some(&first_item) = dead_codes.first() else {
             return;
         };
@@ -1070,9 +1054,6 @@ impl<'tcx> DeadVisitor<'tcx> {
         };
 
         let encl_def_id = parent_item.unwrap_or(first_item.def_id);
-        // If parent of encl_def_id is an enum, use the parent ID intead.
-        let encl_def_id = get_parent_if_enum_variant(tcx, encl_def_id);
-
         let ignored_derived_impls =
             if let Some(ign_traits) = self.ignored_derived_traits.get(&encl_def_id) {
                 let trait_list = ign_traits

tests/ui/lint/dead-code/unused-variant.rs

@@ -6,22 +6,7 @@ enum Enum {
     Variant2,
 }
 
-#[derive(Debug)]
-enum TupleVariant {
-    Variant1(i32), //~ ERROR: variant `Variant1` is never constructed
-    Variant2,
-}
-
-#[derive(Debug)]
-enum StructVariant {
-    Variant1 { id: i32 }, //~ ERROR: variant `Variant1` is never constructed
-    Variant2,
-}
-
 fn main() {
     let e = Enum::Variant2;
     e.clone();
-
-    let _ = TupleVariant::Variant2;
-    let _ = StructVariant::Variant2;
 }

tests/ui/lint/dead-code/unused-variant.stderr

@@ -13,25 +13,5 @@ note: the lint level is defined here
 LL | #![deny(dead_code)]
    |         ^^^^^^^^^
 
-error: variant `Variant1` is never constructed
-  --> $DIR/unused-variant.rs:11:5
-   |
-LL | enum TupleVariant {
-   |      ------------ variant in this enum
-LL |     Variant1(i32),
-   |     ^^^^^^^^
-   |
-   = note: `TupleVariant` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
-
-error: variant `Variant1` is never constructed
-  --> $DIR/unused-variant.rs:17:5
-   |
-LL | enum StructVariant {
-   |      ------------- variant in this enum
-LL |     Variant1 { id: i32 },
-   |     ^^^^^^^^
-   |
-   = note: `StructVariant` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error