diff --git a/clippy_lints/src/len_zero.rs b/clippy_lints/src/len_zero.rs
index 20e6220ec7d..64f6d62fbdc 100644
--- a/clippy_lints/src/len_zero.rs
+++ b/clippy_lints/src/len_zero.rs
@@ -214,14 +214,14 @@ fn fill_trait_set(traitt: DefId, set: &mut DefIdSet, cx: &LateContext<'_>) {
     {
         let mut current_and_super_traits = DefIdSet::default();
         fill_trait_set(visited_trait.def_id.to_def_id(), &mut current_and_super_traits, cx);
+        let is_empty = sym!(is_empty);
 
         let is_empty_method_found = current_and_super_traits
             .iter()
-            .flat_map(|&i| cx.tcx.associated_items(i).in_definition_order())
+            .flat_map(|&i| cx.tcx.associated_items(i).filter_by_name_unhygienic(is_empty))
             .any(|i| {
                 i.kind == ty::AssocKind::Fn
                     && i.fn_has_self_parameter
-                    && i.ident.name == sym!(is_empty)
                     && cx.tcx.fn_sig(i.def_id).inputs().skip_binder().len() == 1
             });
 
@@ -458,7 +458,7 @@ fn is_empty_array(expr: &Expr<'_>) -> bool {
 fn has_is_empty(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     /// Gets an `AssocItem` and return true if it matches `is_empty(self)`.
     fn is_is_empty(cx: &LateContext<'_>, item: &ty::AssocItem) -> bool {
-        if item.kind == ty::AssocKind::Fn && item.ident.name.as_str() == "is_empty" {
+        if item.kind == ty::AssocKind::Fn {
             let sig = cx.tcx.fn_sig(item.def_id);
             let ty = sig.skip_binder();
             ty.inputs().len() == 1
@@ -469,10 +469,11 @@ fn is_is_empty(cx: &LateContext<'_>, item: &ty::AssocItem) -> bool {
 
     /// Checks the inherent impl's items for an `is_empty(self)` method.
     fn has_is_empty_impl(cx: &LateContext<'_>, id: DefId) -> bool {
+        let is_empty = sym!(is_empty);
         cx.tcx.inherent_impls(id).iter().any(|imp| {
             cx.tcx
                 .associated_items(*imp)
-                .in_definition_order()
+                .filter_by_name_unhygienic(is_empty)
                 .any(|item| is_is_empty(cx, item))
         })
     }
@@ -480,9 +481,10 @@ fn has_is_empty_impl(cx: &LateContext<'_>, id: DefId) -> bool {
     let ty = &cx.typeck_results().expr_ty(expr).peel_refs();
     match ty.kind() {
         ty::Dynamic(tt, ..) => tt.principal().map_or(false, |principal| {
+            let is_empty = sym!(is_empty);
             cx.tcx
                 .associated_items(principal.def_id())
-                .in_definition_order()
+                .filter_by_name_unhygienic(is_empty)
                 .any(|item| is_is_empty(cx, item))
         }),
         ty::Projection(ref proj) => has_is_empty_impl(cx, proj.item_def_id),
diff --git a/clippy_lints/src/non_copy_const.rs b/clippy_lints/src/non_copy_const.rs
index 074ba9e92ba..7d2ff083b7e 100644
--- a/clippy_lints/src/non_copy_const.rs
+++ b/clippy_lints/src/non_copy_const.rs
@@ -12,11 +12,10 @@
 use rustc_hir::{
     BodyId, Expr, ExprKind, HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind, Node, TraitItem, TraitItemKind, UnOp,
 };
-use rustc_infer::traits::specialization_graph;
 use rustc_lint::{LateContext, LateLintPass, Lint};
 use rustc_middle::mir::interpret::{ConstValue, ErrorHandled};
 use rustc_middle::ty::adjustment::Adjust;
-use rustc_middle::ty::{self, AssocKind, Const, Ty};
+use rustc_middle::ty::{self, Const, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::{InnerSpan, Span, DUMMY_SP};
 use rustc_typeck::hir_ty_to_ty;
@@ -293,8 +292,10 @@ fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<
                         // Lint a trait impl item only when the definition is a generic type,
                         // assuming an assoc const is not meant to be an interior mutable type.
                         if let Some(of_trait_def_id) = of_trait_ref.trait_def_id();
-                        if let Some(of_assoc_item) = specialization_graph::Node::Trait(of_trait_def_id)
-                            .item(cx.tcx, impl_item.ident, AssocKind::Const, of_trait_def_id);
+                        if let Some(of_assoc_item) = cx
+                            .tcx
+                            .associated_item(impl_item.def_id)
+                            .trait_item_def_id;
                         if cx
                             .tcx
                             .layout_of(cx.tcx.param_env(of_trait_def_id).and(
@@ -303,7 +304,7 @@ fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<
                                 // and, in that case, the definition is *not* generic.
                                 cx.tcx.normalize_erasing_regions(
                                     cx.tcx.param_env(of_trait_def_id),
-                                    cx.tcx.type_of(of_assoc_item.def_id),
+                                    cx.tcx.type_of(of_assoc_item),
                                 ),
                             ))
                             .is_err();
diff --git a/clippy_lints/src/use_self.rs b/clippy_lints/src/use_self.rs
index 059f7f647f8..a86db58741e 100644
--- a/clippy_lints/src/use_self.rs
+++ b/clippy_lints/src/use_self.rs
@@ -13,7 +13,6 @@
 };
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::hir::map::Map;
-use rustc_middle::ty::AssocKind;
 use rustc_semver::RustcVersion;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::Span;
@@ -143,10 +142,10 @@ fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_
                 // trait, not in the impl of the trait.
                 let trait_method = cx
                     .tcx
-                    .associated_items(impl_trait_ref.def_id)
-                    .find_by_name_and_kind(cx.tcx, impl_item.ident, AssocKind::Fn, impl_trait_ref.def_id)
+                    .associated_item(impl_item.def_id)
+                    .trait_item_def_id
                     .expect("impl method matches a trait method");
-                let trait_method_sig = cx.tcx.fn_sig(trait_method.def_id);
+                let trait_method_sig = cx.tcx.fn_sig(trait_method);
                 let trait_method_sig = cx.tcx.erase_late_bound_regions(trait_method_sig);
 
                 // `impl_inputs_outputs` is an iterator over the types (`hir::Ty`) declared in the