Rollup merge of #112670 - petrochenkov:typriv, r=eholk

privacy: Type privacy lints fixes and cleanups

See individual commits.
Follow up to https://github.com/rust-lang/rust/pull/111801.

compiler/rustc_feature/src/active.rs

@@ -543,6 +543,8 @@ pub fn set(&self, features: &mut Features, span: Span) {
     /// Allows creation of instances of a struct by moving fields that have
     /// not changed from prior instances of the same struct (RFC #2528)
     (active, type_changing_struct_update, "1.58.0", Some(86555), None),
+    /// Allows using type privacy lints (`private_interfaces`, `private_bounds`, `unnameable_types`).
+    (active, type_privacy_lints, "CURRENT_RUSTC_VERSION", Some(48054), None),
     /// Enables rustc to generate code that instructs libstd to NOT ignore SIGPIPE.
     (active, unix_sigpipe, "1.65.0", Some(97889), None),
     /// Allows unsized fn parameters.

compiler/rustc_lint/src/builtin.rs

@@ -665,9 +665,7 @@ fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) {
 
 impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
-        if !(cx.effective_visibilities.is_reachable(item.owner_id.def_id)
+        if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
-            && cx.tcx.local_visibility(item.owner_id.def_id).is_public())
-        {
             return;
         }
         let (def, ty) = match item.kind {
@@ -786,9 +784,7 @@ pub struct MissingDebugImplementations {
 
 impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
-        if !(cx.effective_visibilities.is_reachable(item.owner_id.def_id)
+        if !cx.effective_visibilities.is_reachable(item.owner_id.def_id) {
-            && cx.tcx.local_visibility(item.owner_id.def_id).is_public())
-        {
             return;
         }
 

compiler/rustc_lint_defs/src/builtin.rs

@@ -4264,6 +4264,7 @@
     /// ### Example
     ///
     /// ```rust,compile_fail
+    /// # #![feature(type_privacy_lints)]
     /// # #![allow(unused)]
     /// # #![allow(private_in_public)]
     /// #![deny(private_interfaces)]
@@ -4288,6 +4289,7 @@
     pub PRIVATE_INTERFACES,
     Allow,
     "private type in primary interface of an item",
+    @feature_gate = sym::type_privacy_lints;
 }
 
 declare_lint! {
@@ -4298,6 +4300,7 @@
     /// ### Example
     ///
     /// ```rust,compile_fail
+    /// # #![feature(type_privacy_lints)]
     /// # #![allow(private_in_public)]
     /// # #![allow(unused)]
     /// #![deny(private_bounds)]
@@ -4317,7 +4320,8 @@
     /// the item actually provides.
     pub PRIVATE_BOUNDS,
     Allow,
-    "private type in secondary interface of an item"
+    "private type in secondary interface of an item",
+    @feature_gate = sym::type_privacy_lints;
 }
 
 declare_lint! {
@@ -4327,6 +4331,7 @@
     /// ### Example
     ///
     /// ```rust,compile_fail
+    /// # #![feature(type_privacy_lints)]
     /// # #![allow(unused)]
     /// #![deny(unnameable_types)]
     /// mod m {
@@ -4345,5 +4350,6 @@
     /// you can name the type `T` as well, this lint attempts to enforce this rule.
     pub UNNAMEABLE_TYPES,
     Allow,
-    "effective visibility of a type is larger than the area in which it can be named"
+    "effective visibility of a type is larger than the area in which it can be named",
+    @feature_gate = sym::type_privacy_lints;
 }

compiler/rustc_middle/src/middle/privacy.rs

@@ -4,6 +4,7 @@
 use crate::ty::{TyCtxt, Visibility};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hir::def::DefKind;
 use rustc_macros::HashStable;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_span::def_id::{LocalDefId, CRATE_DEF_ID};
@@ -148,13 +149,12 @@ pub fn update_eff_vis(
         };
     }
 
-    pub fn check_invariants(&self, tcx: TyCtxt<'_>, early: bool) {
+    pub fn check_invariants(&self, tcx: TyCtxt<'_>) {
         if !cfg!(debug_assertions) {
             return;
         }
         for (&def_id, ev) in &self.map {
             // More direct visibility levels can never go farther than less direct ones,
-            // neither of effective visibilities can go farther than nominal visibility,
             // and all effective visibilities are larger or equal than private visibility.
             let private_vis = Visibility::Restricted(tcx.parent_module_from_def_id(def_id));
             let span = tcx.def_span(def_id.to_def_id());
@@ -175,17 +175,20 @@ pub fn check_invariants(&self, tcx: TyCtxt<'_>, early: bool) {
                     ev.reachable_through_impl_trait
                 );
             }
-            let nominal_vis = tcx.visibility(def_id);
+            // All effective visibilities except `reachable_through_impl_trait` are limited to
-            // FIXME: `rustc_privacy` is not yet updated for the new logic and can set
+            // nominal visibility. For some items nominal visibility doesn't make sense so we
-            // effective visibilities that are larger than the nominal one.
+            // don't check this condition for them.
-            if !nominal_vis.is_at_least(ev.reachable_through_impl_trait, tcx) && early {
+            if !matches!(tcx.def_kind(def_id), DefKind::Impl { .. }) {
-                span_bug!(
+                let nominal_vis = tcx.visibility(def_id);
-                    span,
+                if !nominal_vis.is_at_least(ev.reachable, tcx) {
-                    "{:?}: reachable_through_impl_trait {:?} > nominal {:?}",
+                    span_bug!(
-                    def_id,
+                        span,
-                    ev.reachable_through_impl_trait,
+                        "{:?}: reachable {:?} > nominal {:?}",
-                    nominal_vis
+                        def_id,
-                );
+                        ev.reachable,
+                        nominal_vis
+                    );
+                }
             }
         }
     }
@@ -212,7 +215,7 @@ pub fn effective_vis_or_private(
     pub fn update(
         &mut self,
         id: Id,
-        nominal_vis: Option<Visibility>,
+        max_vis: Option<Visibility>,
         lazy_private_vis: impl FnOnce() -> Visibility,
         inherited_effective_vis: EffectiveVisibility,
         level: Level,
@@ -236,8 +239,8 @@ pub fn update(
                 if !(inherited_effective_vis_at_prev_level == inherited_effective_vis_at_level
                     && level != l)
                 {
-                    calculated_effective_vis = if let Some(nominal_vis) = nominal_vis && !nominal_vis.is_at_least(inherited_effective_vis_at_level, tcx) {
+                    calculated_effective_vis = if let Some(max_vis) = max_vis && !max_vis.is_at_least(inherited_effective_vis_at_level, tcx) {
-                        nominal_vis
+                        max_vis
                     } else {
                         inherited_effective_vis_at_level
                     }

compiler/rustc_privacy/src/lib.rs

@@ -73,14 +73,10 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 /// in `impl Trait`, see individual comments in `DefIdVisitorSkeleton::visit_ty`.
 trait DefIdVisitor<'tcx> {
     type BreakTy = ();
+    const SHALLOW: bool = false;
+    const SKIP_ASSOC_TYS: bool = false;
 
     fn tcx(&self) -> TyCtxt<'tcx>;
-    fn shallow(&self) -> bool {
-        false
-    }
-    fn skip_assoc_tys(&self) -> bool {
-        false
-    }
     fn visit_def_id(
         &mut self,
         def_id: DefId,
@@ -135,11 +131,7 @@ impl<'tcx, V> DefIdVisitorSkeleton<'_, 'tcx, V>
     fn visit_trait(&mut self, trait_ref: TraitRef<'tcx>) -> ControlFlow<V::BreakTy> {
         let TraitRef { def_id, substs, .. } = trait_ref;
         self.def_id_visitor.visit_def_id(def_id, "trait", &trait_ref.print_only_trait_path())?;
-        if self.def_id_visitor.shallow() {
+        if V::SHALLOW { ControlFlow::Continue(()) } else { substs.visit_with(self) }
-            ControlFlow::Continue(())
-        } else {
-            substs.visit_with(self)
-        }
     }
 
     fn visit_projection_ty(&mut self, projection: ty::AliasTy<'tcx>) -> ControlFlow<V::BreakTy> {
@@ -158,7 +150,7 @@ fn visit_projection_ty(&mut self, projection: ty::AliasTy<'tcx>) -> ControlFlow<
             )
         };
         self.visit_trait(trait_ref)?;
-        if self.def_id_visitor.shallow() {
+        if V::SHALLOW {
             ControlFlow::Continue(())
         } else {
             assoc_substs.iter().try_for_each(|subst| subst.visit_with(self))
@@ -208,7 +200,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
             | ty::Closure(def_id, ..)
             | ty::Generator(def_id, ..) => {
                 self.def_id_visitor.visit_def_id(def_id, "type", &ty)?;
-                if self.def_id_visitor.shallow() {
+                if V::SHALLOW {
                     return ControlFlow::Continue(());
                 }
                 // Default type visitor doesn't visit signatures of fn types.
@@ -232,7 +224,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
                 self.def_id_visitor.visit_def_id(alias.def_id, "type alias", &ty);
             }
             ty::Alias(ty::Projection, proj) => {
-                if self.def_id_visitor.skip_assoc_tys() {
+                if V::SKIP_ASSOC_TYS {
                     // Visitors searching for minimal visibility/reachability want to
                     // conservatively approximate associated types like `<Type as Trait>::Alias`
                     // as visible/reachable even if both `Type` and `Trait` are private.
@@ -244,7 +236,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
                 return self.visit_projection_ty(proj);
             }
             ty::Alias(ty::Inherent, data) => {
-                if self.def_id_visitor.skip_assoc_tys() {
+                if V::SKIP_ASSOC_TYS {
                     // Visitors searching for minimal visibility/reachability want to
                     // conservatively approximate associated types like `Type::Alias`
                     // as visible/reachable even if `Type` is private.
@@ -260,7 +252,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
                 )?;
 
                 // This will also visit substs if necessary, so we don't need to recurse.
-                return if self.def_id_visitor.shallow() {
+                return if V::SHALLOW {
                     ControlFlow::Continue(())
                 } else {
                     data.substs.iter().try_for_each(|subst| subst.visit_with(self))
@@ -319,11 +311,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
             }
         }
 
-        if self.def_id_visitor.shallow() {
+        if V::SHALLOW { ControlFlow::Continue(()) } else { ty.super_visit_with(self) }
-            ControlFlow::Continue(())
-        } else {
-            ty.super_visit_with(self)
-        }
     }
 
     fn visit_const(&mut self, c: Const<'tcx>) -> ControlFlow<Self::BreakTy> {
@@ -340,22 +328,20 @@ fn min(vis1: ty::Visibility, vis2: ty::Visibility, tcx: TyCtxt<'_>) -> ty::Visib
 /// Visitor used to determine impl visibility and reachability.
 ////////////////////////////////////////////////////////////////////////////////
 
-struct FindMin<'a, 'tcx, VL: VisibilityLike> {
+struct FindMin<'a, 'tcx, VL: VisibilityLike, const SHALLOW: bool> {
     tcx: TyCtxt<'tcx>,
     effective_visibilities: &'a EffectiveVisibilities,
     min: VL,
 }
 
-impl<'a, 'tcx, VL: VisibilityLike> DefIdVisitor<'tcx> for FindMin<'a, 'tcx, VL> {
+impl<'a, 'tcx, VL: VisibilityLike, const SHALLOW: bool> DefIdVisitor<'tcx>
+    for FindMin<'a, 'tcx, VL, SHALLOW>
+{
+    const SHALLOW: bool = SHALLOW;
+    const SKIP_ASSOC_TYS: bool = true;
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
-    fn shallow(&self) -> bool {
-        VL::SHALLOW
-    }
-    fn skip_assoc_tys(&self) -> bool {
-        true
-    }
     fn visit_def_id(
         &mut self,
         def_id: DefId,
@@ -371,17 +357,19 @@ fn visit_def_id(
 
 trait VisibilityLike: Sized {
     const MAX: Self;
-    const SHALLOW: bool = false;
+    fn new_min<const SHALLOW: bool>(
-    fn new_min(find: &FindMin<'_, '_, Self>, def_id: LocalDefId) -> Self;
+        find: &FindMin<'_, '_, Self, SHALLOW>,
+        def_id: LocalDefId,
+    ) -> Self;
 
-    // Returns an over-approximation (`skip_assoc_tys` = true) of visibility due to
+    // Returns an over-approximation (`SKIP_ASSOC_TYS` = true) of visibility due to
     // associated types for which we can't determine visibility precisely.
-    fn of_impl(
+    fn of_impl<const SHALLOW: bool>(
         def_id: LocalDefId,
         tcx: TyCtxt<'_>,
         effective_visibilities: &EffectiveVisibilities,
     ) -> Self {
-        let mut find = FindMin { tcx, effective_visibilities, min: Self::MAX };
+        let mut find = FindMin::<_, SHALLOW> { tcx, effective_visibilities, min: Self::MAX };
         find.visit(tcx.type_of(def_id).subst_identity());
         if let Some(trait_ref) = tcx.impl_trait_ref(def_id) {
             find.visit_trait(trait_ref.subst_identity());
@@ -391,49 +379,28 @@ fn of_impl(
 }
 impl VisibilityLike for ty::Visibility {
     const MAX: Self = ty::Visibility::Public;
-    fn new_min(find: &FindMin<'_, '_, Self>, def_id: LocalDefId) -> Self {
+    fn new_min<const SHALLOW: bool>(
+        find: &FindMin<'_, '_, Self, SHALLOW>,
+        def_id: LocalDefId,
+    ) -> Self {
         min(find.tcx.local_visibility(def_id), find.min, find.tcx)
     }
 }
 
-struct NonShallowEffectiveVis(EffectiveVisibility);
+impl VisibilityLike for EffectiveVisibility {
-
+    const MAX: Self = EffectiveVisibility::from_vis(ty::Visibility::Public);
-impl VisibilityLike for NonShallowEffectiveVis {
+    fn new_min<const SHALLOW: bool>(
-    const MAX: Self = NonShallowEffectiveVis(EffectiveVisibility::from_vis(ty::Visibility::Public));
+        find: &FindMin<'_, '_, Self, SHALLOW>,
-    const SHALLOW: bool = false;
+        def_id: LocalDefId,
-
+    ) -> Self {
-    fn new_min(find: &FindMin<'_, '_, Self>, def_id: LocalDefId) -> Self {
-        let find = FindMin {
-            tcx: find.tcx,
-            effective_visibilities: find.effective_visibilities,
-            min: ShallowEffectiveVis(find.min.0),
-        };
-        NonShallowEffectiveVis(VisibilityLike::new_min(&find, def_id).0)
-    }
-}
-
-struct ShallowEffectiveVis(EffectiveVisibility);
-impl VisibilityLike for ShallowEffectiveVis {
-    const MAX: Self = ShallowEffectiveVis(EffectiveVisibility::from_vis(ty::Visibility::Public));
-    // Type inference is very smart sometimes.
-    // It can make an impl reachable even some components of its type or trait are unreachable.
-    // E.g. methods of `impl ReachableTrait<UnreachableTy> for ReachableTy<UnreachableTy> { ... }`
-    // can be usable from other crates (#57264). So we skip substs when calculating reachability
-    // and consider an impl reachable if its "shallow" type and trait are reachable.
-    //
-    // The assumption we make here is that type-inference won't let you use an impl without knowing
-    // both "shallow" version of its self type and "shallow" version of its trait if it exists
-    // (which require reaching the `DefId`s in them).
-    const SHALLOW: bool = true;
-    fn new_min(find: &FindMin<'_, '_, Self>, def_id: LocalDefId) -> Self {
         let effective_vis =
-            find.effective_visibilities.effective_vis(def_id).cloned().unwrap_or_else(|| {
+            find.effective_visibilities.effective_vis(def_id).copied().unwrap_or_else(|| {
                 let private_vis =
                     ty::Visibility::Restricted(find.tcx.parent_module_from_def_id(def_id));
                 EffectiveVisibility::from_vis(private_vis)
             });
 
-        ShallowEffectiveVis(effective_vis.min(find.min.0, find.tcx))
+        effective_vis.min(find.min, find.tcx)
     }
 }
 
@@ -492,14 +459,14 @@ fn update_eff_vis(
         &mut self,
         def_id: LocalDefId,
         inherited_effective_vis: EffectiveVisibility,
-        nominal_vis: Option<ty::Visibility>,
+        max_vis: Option<ty::Visibility>,
         level: Level,
     ) {
         let private_vis = ty::Visibility::Restricted(self.tcx.parent_module_from_def_id(def_id));
-        if Some(private_vis) != nominal_vis {
+        if max_vis != Some(private_vis) {
             self.changed |= self.effective_visibilities.update(
                 def_id,
-                nominal_vis,
+                max_vis,
                 || private_vis,
                 inherited_effective_vis,
                 level,
@@ -771,12 +738,21 @@ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
                 }
             }
             hir::ItemKind::Impl(ref impl_) => {
-                let item_ev = ShallowEffectiveVis::of_impl(
+                // Type inference is very smart sometimes. It can make an impl reachable even some
+                // components of its type or trait are unreachable. E.g. methods of
+                // `impl ReachableTrait<UnreachableTy> for ReachableTy<UnreachableTy> { ... }`
+                // can be usable from other crates (#57264). So we skip substs when calculating
+                // reachability and consider an impl reachable if its "shallow" type and trait are
+                // reachable.
+                //
+                // The assumption we make here is that type-inference won't let you use an impl
+                // without knowing both "shallow" version of its self type and "shallow" version of
+                // its trait if it exists (which require reaching the `DefId`s in them).
+                let item_ev = EffectiveVisibility::of_impl::<true>(
                     item.owner_id.def_id,
                     self.tcx,
                     &self.effective_visibilities,
-                )
+                );
-                .0;
 
                 self.update_eff_vis(item.owner_id.def_id, item_ev, None, Level::Direct);
 
@@ -784,9 +760,9 @@ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
 
                 for impl_item_ref in impl_.items {
                     let def_id = impl_item_ref.id.owner_id.def_id;
-                    let nominal_vis =
+                    let max_vis =
                         impl_.of_trait.is_none().then(|| self.tcx.local_visibility(def_id));
-                    self.update_eff_vis(def_id, item_ev, nominal_vis, Level::Direct);
+                    self.update_eff_vis(def_id, item_ev, max_vis, Level::Direct);
 
                     if let Some(impl_item_ev) = self.get(def_id) {
                         self.reach(def_id, impl_item_ev).generics().predicates().ty();
@@ -904,7 +880,12 @@ fn visit_def_id(
         _descr: &dyn fmt::Display,
     ) -> ControlFlow<Self::BreakTy> {
         if let Some(def_id) = def_id.as_local() {
-            self.ev.update_eff_vis(def_id, self.effective_vis, None, self.level);
+            // All effective visibilities except `reachable_through_impl_trait` are limited to
+            // nominal visibility. If any type or trait is leaked farther than that, it will
+            // produce type privacy errors on any use, so we don't consider it leaked.
+            let max_vis = (self.level != Level::ReachableThroughImplTrait)
+                .then(|| self.ev.tcx.local_visibility(def_id));
+            self.ev.update_eff_vis(def_id, self.effective_vis, max_vis, self.level);
         }
         ControlFlow::Continue(())
     }
@@ -1876,10 +1857,9 @@ fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display)
             return false;
         };
 
-        // FIXME: `Level::Reachable` should be taken instead of `Level::Reexported`
+        let reachable_at_vis = *effective_vis.at_level(Level::Reachable);
-        let reexported_at_vis = *effective_vis.at_level(Level::Reexported);
 
-        if !vis.is_at_least(reexported_at_vis, self.tcx) {
+        if !vis.is_at_least(reachable_at_vis, self.tcx) {
             let lint = if self.in_primary_interface {
                 lint::builtin::PRIVATE_INTERFACES
             } else {
@@ -1896,7 +1876,7 @@ fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display)
                         tcx: self.tcx,
                     })
                         .into(),
-                    item_vis_descr: &vis_to_string(self.item_def_id, reexported_at_vis, self.tcx),
+                    item_vis_descr: &vis_to_string(self.item_def_id, reachable_at_vis, self.tcx),
                     ty_span: vis_span,
                     ty_kind: kind,
                     ty_descr: descr.into(),
@@ -2137,27 +2117,28 @@ pub fn check_item(&mut self, id: ItemId) {
             DefKind::Impl { .. } => {
                 let item = tcx.hir().item(id);
                 if let hir::ItemKind::Impl(ref impl_) = item.kind {
-                    let impl_vis =
+                    let impl_vis = ty::Visibility::of_impl::<false>(
-                        ty::Visibility::of_impl(item.owner_id.def_id, tcx, &Default::default());
+                        item.owner_id.def_id,
+                        tcx,
+                        &Default::default(),
+                    );
 
-                    // we are using the non-shallow version here, unlike when building the
+                    // We are using the non-shallow version here, unlike when building the
                     // effective visisibilities table to avoid large number of false positives.
-                    // For example:
+                    // For example in
                     //
                     // impl From<Priv> for Pub {
                     //     fn from(_: Priv) -> Pub {...}
                     // }
                     //
-                    // lints shouldn't be emmited even `from` effective visibility
+                    // lints shouldn't be emmited even if `from` effective visibility
-                    // is larger then `Priv` nominal visibility.
+                    // is larger than `Priv` nominal visibility and if `Priv` can leak
-                    let impl_ev = Some(
+                    // in some scenarios due to type inference.
-                        NonShallowEffectiveVis::of_impl(
+                    let impl_ev = Some(EffectiveVisibility::of_impl::<false>(
-                            item.owner_id.def_id,
+                        item.owner_id.def_id,
-                            tcx,
+                        tcx,
-                            self.effective_visibilities,
+                        self.effective_visibilities,
-                        )
+                    ));
-                        .0,
-                    );
 
                     // check that private components do not appear in the generics or predicates of inherent impls
                     // this check is intentionally NOT performed for impls of traits, per #90586
@@ -2284,7 +2265,7 @@ fn effective_visibilities(tcx: TyCtxt<'_>, (): ()) -> &EffectiveVisibilities {
         changed: false,
     };
 
-    visitor.effective_visibilities.check_invariants(tcx, true);
+    visitor.effective_visibilities.check_invariants(tcx);
     if visitor.impl_trait_pass {
         // Underlying types of `impl Trait`s are marked as reachable unconditionally,
         // so this pass doesn't need to be a part of the fixed point iteration below.
@@ -2301,7 +2282,7 @@ fn effective_visibilities(tcx: TyCtxt<'_>, (): ()) -> &EffectiveVisibilities {
             break;
         }
     }
-    visitor.effective_visibilities.check_invariants(tcx, false);
+    visitor.effective_visibilities.check_invariants(tcx);
 
     let mut check_visitor =
         TestReachabilityVisitor { tcx, effective_visibilities: &visitor.effective_visibilities };

compiler/rustc_span/src/symbol.rs

@@ -1558,6 +1558,7 @@
         type_length_limit,
         type_macros,
         type_name,
+        type_privacy_lints,
         u128,
         u16,
         u32,

library/core/src/iter/adapters/flatten.rs

@@ -310,7 +310,7 @@ fn default() -> Self {
 /// Real logic of both `Flatten` and `FlatMap` which simply delegate to
 /// this type.
 #[derive(Clone, Debug)]
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 struct FlattenCompat<I, U> {
     iter: Fuse<I>,
     frontiter: Option<U>,
@@ -464,7 +464,7 @@ fn flatten<'a, T: IntoIterator, Acc, R: Try>(
     }
 }
 
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 impl<I, U> Iterator for FlattenCompat<I, U>
 where
     I: Iterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
@@ -579,7 +579,7 @@ fn last<U: Iterator>(last: Option<U::Item>, iter: U) -> Option<U::Item> {
     }
 }
 
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 impl<I, U> DoubleEndedIterator for FlattenCompat<I, U>
 where
     I: DoubleEndedIterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
@@ -649,7 +649,7 @@ fn advance<U: DoubleEndedIterator>(n: usize, iter: &mut U) -> ControlFlow<(), us
     }
 }
 
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 unsafe impl<const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <[T; N] as IntoIterator>::IntoIter>
 where
@@ -657,7 +657,7 @@ unsafe impl<const N: usize, I, T> TrustedLen
 {
 }
 
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 unsafe impl<'a, const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <&'a [T; N] as IntoIterator>::IntoIter>
 where
@@ -665,7 +665,7 @@ unsafe impl<'a, const N: usize, I, T> TrustedLen
 {
 }
 
-#[unstable(feature = "trusted_len", issue = "37572")]
+#[cfg_attr(bootstrap, unstable(feature = "trusted_len", issue = "37572"))]
 unsafe impl<'a, const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <&'a mut [T; N] as IntoIterator>::IntoIter>
 where

tests/ui/associated-inherent-types/private-in-public.rs

@@ -1,7 +1,7 @@
 #![feature(inherent_associated_types)]
+#![feature(type_privacy_lints)]
 #![allow(incomplete_features)]
 #![crate_type = "lib"]
-
 #![deny(private_in_public)]
 #![warn(private_interfaces)]
 

tests/ui/const-generics/generic_const_exprs/eval-privacy.rs

@@ -1,7 +1,7 @@
 #![crate_type = "lib"]
 #![feature(generic_const_exprs)]
+#![feature(type_privacy_lints)]
 #![allow(incomplete_features)]
-
 #![warn(private_interfaces)]
 
 // In this test both old and new private-in-public diagnostic were emitted.

tests/ui/error-codes/E0445.rs

@@ -1,3 +1,4 @@
+#![feature(type_privacy_lints)]
 #[warn(private_bounds)]
 #[warn(private_interfaces)]
 

tests/ui/error-codes/E0445.stderr

@@ -1,5 +1,5 @@
 error[E0445]: private trait `Foo` in public interface
-  --> $DIR/E0445.rs:12:1
+  --> $DIR/E0445.rs:13:1
    |
 LL | trait Foo {
    | --------- `Foo` declared as private
@@ -10,23 +10,23 @@ LL | pub trait Bar : Foo {}
 warning: trait `Foo` is more private than the item `Bar`
    |
 note: trait `Bar` is reachable at visibility `pub`
-  --> $DIR/E0445.rs:12:1
+  --> $DIR/E0445.rs:13:1
    |
 LL | pub trait Bar : Foo {}
    | ^^^^^^^^^^^^^^^^^^^
 note: but trait `Foo` is only usable at visibility `pub(crate)`
-  --> $DIR/E0445.rs:8:1
+  --> $DIR/E0445.rs:9:1
    |
 LL | trait Foo {
    | ^^^^^^^^^
 note: the lint level is defined here
-  --> $DIR/E0445.rs:1:8
+  --> $DIR/E0445.rs:2:8
    |
 LL | #[warn(private_bounds)]
    |        ^^^^^^^^^^^^^^
 
 error[E0445]: private trait `Foo` in public interface
-  --> $DIR/E0445.rs:14:1
+  --> $DIR/E0445.rs:15:1
    |
 LL | trait Foo {
    | --------- `Foo` declared as private
@@ -37,18 +37,18 @@ LL | pub struct Bar2<T: Foo>(pub T);
 warning: trait `Foo` is more private than the item `Bar2`
    |
 note: struct `Bar2` is reachable at visibility `pub`
-  --> $DIR/E0445.rs:14:1
+  --> $DIR/E0445.rs:15:1
    |
 LL | pub struct Bar2<T: Foo>(pub T);
    | ^^^^^^^^^^^^^^^^^^^^^^^
 note: but trait `Foo` is only usable at visibility `pub(crate)`
-  --> $DIR/E0445.rs:8:1
+  --> $DIR/E0445.rs:9:1
    |
 LL | trait Foo {
    | ^^^^^^^^^
 
 error[E0445]: private trait `Foo` in public interface
-  --> $DIR/E0445.rs:16:1
+  --> $DIR/E0445.rs:17:1
    |
 LL | trait Foo {
    | --------- `Foo` declared as private
@@ -59,12 +59,12 @@ LL | pub fn foo<T: Foo> (t: T) {}
 warning: trait `Foo` is more private than the item `foo`
    |
 note: function `foo` is reachable at visibility `pub`
-  --> $DIR/E0445.rs:16:1
+  --> $DIR/E0445.rs:17:1
    |
 LL | pub fn foo<T: Foo> (t: T) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
 note: but trait `Foo` is only usable at visibility `pub(crate)`
-  --> $DIR/E0445.rs:8:1
+  --> $DIR/E0445.rs:9:1
    |
 LL | trait Foo {
    | ^^^^^^^^^

tests/ui/feature-gates/feature-gate-type_privacy_lints.rs

@@ -0,0 +1,12 @@
+// check-pass
+
+#![warn(private_interfaces)] //~ WARN unknown lint
+                             //~| WARN unknown lint
+                             //~| WARN unknown lint
+#![warn(private_bounds)] //~ WARN unknown lint
+                         //~| WARN unknown lint
+                         //~| WARN unknown lint
+#![warn(unnameable_types)] //~ WARN unknown lint
+                           //~| WARN unknown lint
+                           //~| WARN unknown lint
+fn main() {}

tests/ui/feature-gates/feature-gate-type_privacy_lints.stderr

@@ -0,0 +1,93 @@
+warning: unknown lint: `private_interfaces`
+  --> $DIR/feature-gate-type_privacy_lints.rs:3:1
+   |
+LL | #![warn(private_interfaces)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_interfaces` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+   = note: `#[warn(unknown_lints)]` on by default
+
+warning: unknown lint: `private_bounds`
+  --> $DIR/feature-gate-type_privacy_lints.rs:6:1
+   |
+LL | #![warn(private_bounds)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_bounds` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `unnameable_types`
+  --> $DIR/feature-gate-type_privacy_lints.rs:9:1
+   |
+LL | #![warn(unnameable_types)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `unnameable_types` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `private_interfaces`
+  --> $DIR/feature-gate-type_privacy_lints.rs:3:1
+   |
+LL | #![warn(private_interfaces)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_interfaces` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `private_bounds`
+  --> $DIR/feature-gate-type_privacy_lints.rs:6:1
+   |
+LL | #![warn(private_bounds)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_bounds` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `unnameable_types`
+  --> $DIR/feature-gate-type_privacy_lints.rs:9:1
+   |
+LL | #![warn(unnameable_types)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `unnameable_types` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `private_interfaces`
+  --> $DIR/feature-gate-type_privacy_lints.rs:3:1
+   |
+LL | #![warn(private_interfaces)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_interfaces` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `private_bounds`
+  --> $DIR/feature-gate-type_privacy_lints.rs:6:1
+   |
+LL | #![warn(private_bounds)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `private_bounds` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: unknown lint: `unnameable_types`
+  --> $DIR/feature-gate-type_privacy_lints.rs:9:1
+   |
+LL | #![warn(unnameable_types)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `unnameable_types` lint is unstable
+   = note: see issue #48054 <https://github.com/rust-lang/rust/issues/48054> for more information
+   = help: add `#![feature(type_privacy_lints)]` to the crate attributes to enable
+
+warning: 9 warnings emitted
+

tests/ui/issues/issue-18389.rs

@@ -1,3 +1,4 @@
+#![feature(type_privacy_lints)]
 #![warn(private_bounds)]
 
 // In this test both old and new private-in-public diagnostic were emitted.

tests/ui/issues/issue-18389.stderr

@@ -1,5 +1,5 @@
 error[E0445]: private trait `Private<<Self as Public>::P, <Self as Public>::R>` in public interface
-  --> $DIR/issue-18389.rs:13:1
+  --> $DIR/issue-18389.rs:14:1
    |
 LL |   trait Private<P, R> {
    |   ------------------- `Private<<Self as Public>::P, <Self as Public>::R>` declared as private
@@ -14,7 +14,7 @@ LL | | > {
 warning: trait `Private<<Self as Public>::P, <Self as Public>::R>` is more private than the item `Public`
    |
 note: trait `Public` is reachable at visibility `pub`
-  --> $DIR/issue-18389.rs:13:1
+  --> $DIR/issue-18389.rs:14:1
    |
 LL | / pub trait Public: Private<
 LL | |
@@ -23,12 +23,12 @@ LL | |     <Self as Public>::R
 LL | | > {
    | |_^
 note: but trait `Private<<Self as Public>::P, <Self as Public>::R>` is only usable at visibility `pub(crate)`
-  --> $DIR/issue-18389.rs:10:1
+  --> $DIR/issue-18389.rs:11:1
    |
 LL | trait Private<P, R> {
    | ^^^^^^^^^^^^^^^^^^^
 note: the lint level is defined here
-  --> $DIR/issue-18389.rs:1:9
+  --> $DIR/issue-18389.rs:2:9
    |
 LL | #![warn(private_bounds)]
    |         ^^^^^^^^^^^^^^

tests/ui/privacy/effective_visibilities_full_priv.rs

@@ -6,7 +6,7 @@
 mod m {
     #[rustc_effective_visibility]
     struct Priv;
-    //~^ ERROR Direct: pub(self), Reexported: pub(self), Reachable: pub(crate), ReachableThroughImplTrait: pub(crate)
+    //~^ ERROR not in the table
     //~| ERROR not in the table
 
     #[rustc_effective_visibility]

tests/ui/privacy/effective_visibilities_full_priv.stderr

@@ -1,4 +1,4 @@
-error: Direct: pub(self), Reexported: pub(self), Reachable: pub(crate), ReachableThroughImplTrait: pub(crate)
+error: not in the table
   --> $DIR/effective_visibilities_full_priv.rs:8:5
    |
 LL |     struct Priv;

tests/ui/privacy/private-in-public-non-principal.rs

@@ -1,6 +1,6 @@
 #![feature(auto_traits)]
 #![feature(negative_impls)]
-
+#![feature(type_privacy_lints)]
 #![deny(private_interfaces)]
 
 // In this test both old and new private-in-public diagnostic were emitted.

tests/ui/privacy/unnameable_types.rs

@@ -1,4 +1,4 @@
-#![allow(unused)]
+#![feature(type_privacy_lints)]
 #![allow(private_in_public)]
 #![deny(unnameable_types)]
 

tests/ui/privacy/where-priv-type.rs

@@ -3,8 +3,8 @@
 
 #![crate_type = "lib"]
 #![feature(generic_const_exprs)]
+#![feature(type_privacy_lints)]
 #![allow(incomplete_features)]
-
 #![warn(private_bounds)]
 #![warn(private_interfaces)]
 

tests/ui/privacy/where-pub-type-impls-priv-trait.rs

@@ -2,8 +2,8 @@
 
 #![crate_type = "lib"]
 #![feature(generic_const_exprs)]
+#![feature(type_privacy_lints)]
 #![allow(incomplete_features)]
-
 #![warn(private_bounds)]
 
 // In this test both old and new private-in-public diagnostic were emitted.

tests/ui/pub/issue-33174-restricted-type-in-public-interface.rs

@@ -1,3 +1,4 @@
+#![feature(type_privacy_lints)]
 #![allow(non_camel_case_types)] // genus is always capitalized
 #![warn(private_interfaces)]
 //~^ NOTE the lint level is defined here

tests/ui/pub/issue-33174-restricted-type-in-public-interface.stderr

@@ -1,5 +1,5 @@
 error[E0446]: private type `Snail` in public interface
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:27:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:28:1
    |
 LL | pub(crate) struct Snail;
    | ----------------------- `Snail` declared as private
@@ -10,23 +10,23 @@ LL | pub type Helix_pomatia = Shell<Snail>;
 warning: type `Snail` is more private than the item `Helix_pomatia`
    |
 note: type alias `Helix_pomatia` is reachable at visibility `pub`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:27:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:28:1
    |
 LL | pub type Helix_pomatia = Shell<Snail>;
    | ^^^^^^^^^^^^^^^^^^^^^^
 note: but type `Snail` is only usable at visibility `pub(crate)`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:9:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:10:1
    |
 LL | pub(crate) struct Snail;
    | ^^^^^^^^^^^^^^^^^^^^^^^
 note: the lint level is defined here
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:2:9
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:3:9
    |
 LL | #![warn(private_interfaces)]
    |         ^^^^^^^^^^^^^^^^^^
 
 error[E0446]: crate-private type `Turtle` in public interface
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:31:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:32:1
    |
 LL |     pub(super) struct Turtle;
    |     ------------------------ `Turtle` declared as crate-private
@@ -37,18 +37,18 @@ LL | pub type Dermochelys_coriacea = Shell<sea::Turtle>;
 warning: type `Turtle` is more private than the item `Dermochelys_coriacea`
    |
 note: type alias `Dermochelys_coriacea` is reachable at visibility `pub`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:31:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:32:1
    |
 LL | pub type Dermochelys_coriacea = Shell<sea::Turtle>;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: but type `Turtle` is only usable at visibility `pub(crate)`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:14:5
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:15:5
    |
 LL |     pub(super) struct Turtle;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0446]: private type `Tortoise` in public interface
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:35:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:36:1
    |
 LL | struct Tortoise;
    | --------------- `Tortoise` declared as private
@@ -59,12 +59,12 @@ LL | pub type Testudo_graeca = Shell<Tortoise>;
 warning: type `Tortoise` is more private than the item `Testudo_graeca`
    |
 note: type alias `Testudo_graeca` is reachable at visibility `pub`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:35:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:36:1
    |
 LL | pub type Testudo_graeca = Shell<Tortoise>;
    | ^^^^^^^^^^^^^^^^^^^^^^^
 note: but type `Tortoise` is only usable at visibility `pub(crate)`
-  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:19:1
+  --> $DIR/issue-33174-restricted-type-in-public-interface.rs:20:1
    |
 LL | struct Tortoise;
    | ^^^^^^^^^^^^^^^