Remove CheckConstTraitVisitor

Signed-off-by: Miguel Guarniz <mi9uel9@gmail.com>

compiler/rustc_passes/src/check_const.rs

@@ -10,6 +10,7 @@
 use rustc_attr as attr;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_middle::hir::nested_filter;
@@ -58,38 +59,31 @@ impl NonConstExpr {
 fn check_mod_const_bodies(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     let mut vis = CheckConstVisitor::new(tcx);
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut vis.as_deep_visitor());
-    tcx.hir().visit_item_likes_in_module(module_def_id, &mut CheckConstTraitVisitor::new(tcx));
+    for id in tcx.hir_module_items(module_def_id).items() {
+        check_item(tcx, id);
+    }
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_const_bodies, ..*providers };
 }
 
-struct CheckConstTraitVisitor<'tcx> {
+fn check_item<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
-    tcx: TyCtxt<'tcx>,
-}
-
-impl<'tcx> CheckConstTraitVisitor<'tcx> {
-    fn new(tcx: TyCtxt<'tcx>) -> Self {
-        CheckConstTraitVisitor { tcx }
-    }
-}
-
-impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<'tcx> {
-    /// check for const trait impls, and errors if the impl uses provided/default functions
-    /// of the trait being implemented; as those provided functions can be non-const.
-    fn visit_item<'hir>(&mut self, item: &'hir hir::Item<'hir>) {
     let _: Option<_> = try {
+        if !matches!(tcx.hir().def_kind(id.def_id), DefKind::Impl) {
+            None?
+        }
+
+        let item = tcx.hir().item(id);
         if let hir::ItemKind::Impl(ref imp) = item.kind && let hir::Constness::Const = imp.constness {
             let trait_def_id = imp.of_trait.as_ref()?.trait_def_id()?;
-                    let ancestors = self
+            let ancestors = tcx
-                        .tcx
                 .trait_def(trait_def_id)
-                        .ancestors(self.tcx, item.def_id.to_def_id())
+                .ancestors(tcx, item.def_id.to_def_id())
                 .ok()?;
             let mut to_implement = Vec::new();
 
-                    for trait_item in self.tcx.associated_items(trait_def_id).in_definition_order()
+            for trait_item in tcx.associated_items(trait_def_id).in_definition_order()
             {
                 if let ty::AssocItem {
                     kind: ty::AssocKind::Fn,
@@ -101,20 +95,19 @@ impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<
                     // we can ignore functions that do not have default bodies:
                     // if those are unimplemented it will be caught by typeck.
                     if !defaultness.has_value()
-                                || self
+                        || tcx
-                                    .tcx
                         .has_attr(trait_item_id, sym::default_method_body_is_const)
                     {
                         continue;
                     }
 
                     let is_implemented = ancestors
-                                .leaf_def(self.tcx, trait_item_id)
+                        .leaf_def(tcx, trait_item_id)
                         .map(|node_item| !node_item.defining_node.is_from_trait())
                         .unwrap_or(false);
 
                     if !is_implemented {
-                                to_implement.push(self.tcx.item_name(trait_item_id).to_string());
+                        to_implement.push(tcx.item_name(trait_item_id).to_string());
                     }
                 }
             }
@@ -122,7 +115,7 @@ impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<
             // all nonconst trait functions (not marked with #[default_method_body_is_const])
             // must be implemented
             if !to_implement.is_empty() {
-                        self.tcx
+                tcx
                     .sess
                     .struct_span_err(
                         item.span,
@@ -133,13 +126,6 @@ impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<
             }
         }
     };
-    }
-
-    fn visit_trait_item<'hir>(&mut self, _: &'hir hir::TraitItem<'hir>) {}
-
-    fn visit_impl_item<'hir>(&mut self, _: &'hir hir::ImplItem<'hir>) {}
-
-    fn visit_foreign_item<'hir>(&mut self, _: &'hir hir::ForeignItem<'hir>) {}
 }
 
 #[derive(Copy, Clone)]