diff --git a/compiler/rustc_privacy/src/errors.rs b/compiler/rustc_privacy/src/errors.rs
index 89face10750..34553c2b90a 100644
--- a/compiler/rustc_privacy/src/errors.rs
+++ b/compiler/rustc_privacy/src/errors.rs
@@ -5,7 +5,7 @@
 
 #[derive(Diagnostic)]
 #[diag(privacy_field_is_private, code = E0451)]
-pub struct FieldIsPrivate {
+pub(crate) struct FieldIsPrivate {
     #[primary_span]
     pub span: Span,
     pub field_name: Symbol,
@@ -16,7 +16,7 @@ pub struct FieldIsPrivate {
 }
 
 #[derive(Subdiagnostic)]
-pub enum FieldIsPrivateLabel {
+pub(crate) enum FieldIsPrivateLabel {
     #[label(privacy_field_is_private_is_update_syntax_label)]
     IsUpdateSyntax {
         #[primary_span]
@@ -32,7 +32,7 @@ pub enum FieldIsPrivateLabel {
 
 #[derive(Diagnostic)]
 #[diag(privacy_item_is_private)]
-pub struct ItemIsPrivate<'a> {
+pub(crate) struct ItemIsPrivate<'a> {
     #[primary_span]
     #[label]
     pub span: Span,
@@ -42,7 +42,7 @@ pub struct ItemIsPrivate<'a> {
 
 #[derive(Diagnostic)]
 #[diag(privacy_unnamed_item_is_private)]
-pub struct UnnamedItemIsPrivate {
+pub(crate) struct UnnamedItemIsPrivate {
     #[primary_span]
     pub span: Span,
     pub kind: &'static str,
@@ -50,7 +50,7 @@ pub struct UnnamedItemIsPrivate {
 
 #[derive(Diagnostic)]
 #[diag(privacy_in_public_interface, code = E0446)]
-pub struct InPublicInterface<'a> {
+pub(crate) struct InPublicInterface<'a> {
     #[primary_span]
     #[label]
     pub span: Span,
@@ -63,7 +63,7 @@ pub struct InPublicInterface<'a> {
 
 #[derive(Diagnostic)]
 #[diag(privacy_report_effective_visibility)]
-pub struct ReportEffectiveVisibility {
+pub(crate) struct ReportEffectiveVisibility {
     #[primary_span]
     pub span: Span,
     pub descr: String,
@@ -71,7 +71,7 @@ pub struct ReportEffectiveVisibility {
 
 #[derive(LintDiagnostic)]
 #[diag(privacy_from_private_dep_in_public_interface)]
-pub struct FromPrivateDependencyInPublicInterface<'a> {
+pub(crate) struct FromPrivateDependencyInPublicInterface<'a> {
     pub kind: &'a str,
     pub descr: DiagArgFromDisplay<'a>,
     pub krate: Symbol,
@@ -79,7 +79,7 @@ pub struct FromPrivateDependencyInPublicInterface<'a> {
 
 #[derive(LintDiagnostic)]
 #[diag(privacy_unnameable_types_lint)]
-pub struct UnnameableTypesLint<'a> {
+pub(crate) struct UnnameableTypesLint<'a> {
     #[label]
     pub span: Span,
     pub kind: &'a str,
@@ -93,7 +93,7 @@ pub struct UnnameableTypesLint<'a> {
 // See https://rust-lang.github.io/rfcs/2145-type-privacy.html for more details.
 #[derive(LintDiagnostic)]
 #[diag(privacy_private_interface_or_bounds_lint)]
-pub struct PrivateInterfacesOrBoundsLint<'a> {
+pub(crate) struct PrivateInterfacesOrBoundsLint<'a> {
     #[label(privacy_item_label)]
     pub item_span: Span,
     pub item_kind: &'a str,
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 9f78215bfd1..572f71d7c77 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -6,6 +6,7 @@
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod errors;
@@ -1497,7 +1498,7 @@ fn get(&self, def_id: LocalDefId) -> Option<EffectiveVisibility> {
         self.effective_visibilities.effective_vis(def_id).copied()
     }
 
-    pub fn check_item(&mut self, id: ItemId) {
+    fn check_item(&mut self, id: ItemId) {
         let tcx = self.tcx;
         let def_id = id.owner_id.def_id;
         let item_visibility = tcx.local_visibility(def_id);