diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 91617f2df9c..1c76c31e1a7 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -888,8 +888,10 @@ fn resolve_macro_invocation(
     /// Some parent node that is close enough to the given macro call.
     fn lint_node_id(&mut self, expn_id: ExpnId) -> NodeId;
 
+    // Resolver interfaces for specific built-in macros.
+    /// Does `#[derive(...)]` attribute with the given `ExpnId` have built-in `Copy` inside it?
     fn has_derive_copy(&self, expn_id: ExpnId) -> bool;
-    fn add_derive_copy(&mut self, expn_id: ExpnId);
+    /// Path resolution logic for `#[cfg_accessible(path)]`.
     fn cfg_accessible(&mut self, expn_id: ExpnId, path: &ast::Path) -> Result<bool, Indeterminate>;
 }
 
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index d4a83b80990..f4b66b35420 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1797,7 +1797,4 @@ pub fn default(crate_name: String) -> ExpansionConfig<'static> {
     fn proc_macro_hygiene(&self) -> bool {
         self.features.map_or(false, |features| features.proc_macro_hygiene)
     }
-    fn custom_inner_attributes(&self) -> bool {
-        self.features.map_or(false, |features| features.custom_inner_attributes)
-    }
 }
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 3738fbaeac8..41985757b57 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -312,14 +312,13 @@ fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
 }
 
 pub fn maybe_needs_tokens(attrs: &[ast::Attribute]) -> bool {
+    // One of the attributes may either itself be a macro, or apply derive macros (`derive`),
+    // or expand to macro attributes (`cfg_attr`).
     attrs.iter().any(|attr| {
-        if let Some(ident) = attr.ident() {
+        attr.ident().map_or(true, |ident| {
             ident.name == sym::derive
-            // This might apply a custom attribute/derive
-            || ident.name == sym::cfg_attr
-            || !rustc_feature::is_builtin_attr_name(ident.name)
-        } else {
-            true
-        }
+                || ident.name == sym::cfg_attr
+                || !rustc_feature::is_builtin_attr_name(ident.name)
+        })
     })
 }
diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index b1ea2d73786..1ee96f81e4f 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -286,7 +286,7 @@ fn resolve_macro_invocation(
                                     ext.helper_attrs.iter().map(|name| Ident::new(*name, span)),
                                 );
                                 if ext.is_derive_copy {
-                                    self.add_derive_copy(invoc_id);
+                                    self.containers_deriving_copy.insert(invoc_id);
                                 }
                                 ext
                             }
@@ -351,10 +351,6 @@ fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
         self.containers_deriving_copy.contains(&expn_id)
     }
 
-    fn add_derive_copy(&mut self, expn_id: ExpnId) {
-        self.containers_deriving_copy.insert(expn_id);
-    }
-
     // The function that implements the resolution logic of `#[cfg_accessible(path)]`.
     // Returns true if the path can certainly be resolved in one of three namespaces,
     // returns false if the path certainly cannot be resolved in any of the three namespaces.