Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 2185 insertions, 0 deletions

diff --git a/compiler/rustc_privacy/src/errors.rs b/compiler/rustc_privacy/src/errors.rs
new file mode 100644
index 000000000..aca7d770f
--- /dev/null
+++ b/compiler/rustc_privacy/src/errors.rs
@@ -0,0 +1,92 @@
+use rustc_errors::DiagnosticArgFromDisplay;
+use rustc_macros::{LintDiagnostic, SessionDiagnostic, SessionSubdiagnostic};
+use rustc_span::{Span, Symbol};
+
+#[derive(SessionDiagnostic)]
+#[error(privacy::field_is_private, code = "E0451")]
+pub struct FieldIsPrivate {
+    #[primary_span]
+    pub span: Span,
+    pub field_name: Symbol,
+    pub variant_descr: &'static str,
+    pub def_path_str: String,
+    #[subdiagnostic]
+    pub label: FieldIsPrivateLabel,
+}
+
+#[derive(SessionSubdiagnostic)]
+pub enum FieldIsPrivateLabel {
+    #[label(privacy::field_is_private_is_update_syntax_label)]
+    IsUpdateSyntax {
+        #[primary_span]
+        span: Span,
+        field_name: Symbol,
+    },
+    #[label(privacy::field_is_private_label)]
+    Other {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+#[derive(SessionDiagnostic)]
+#[error(privacy::item_is_private)]
+pub struct ItemIsPrivate<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+}
+
+#[derive(SessionDiagnostic)]
+#[error(privacy::unnamed_item_is_private)]
+pub struct UnnamedItemIsPrivate {
+    #[primary_span]
+    pub span: Span,
+    pub kind: &'static str,
+}
+
+// Duplicate of `InPublicInterface` but with a different error code, shares the same slug.
+#[derive(SessionDiagnostic)]
+#[error(privacy::in_public_interface, code = "E0445")]
+pub struct InPublicInterfaceTraits<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub vis_descr: &'static str,
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+    #[label(privacy::visibility_label)]
+    pub vis_span: Span,
+}
+
+// Duplicate of `InPublicInterfaceTraits` but with a different error code, shares the same slug.
+#[derive(SessionDiagnostic)]
+#[error(privacy::in_public_interface, code = "E0446")]
+pub struct InPublicInterface<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub vis_descr: &'static str,
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+    #[label(privacy::visibility_label)]
+    pub vis_span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[lint(privacy::from_private_dep_in_public_interface)]
+pub struct FromPrivateDependencyInPublicInterface<'a> {
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+    pub krate: Symbol,
+}
+
+#[derive(LintDiagnostic)]
+#[lint(privacy::private_in_public_lint)]
+pub struct PrivateInPublicLint<'a> {
+    pub vis_descr: &'static str,
+    pub kind: &'a str,
+    pub descr: DiagnosticArgFromDisplay<'a>,
+}
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
new file mode 100644
index 000000000..c28d0569d
--- /dev/null
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -0,0 +1,2093 @@
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![feature(associated_type_defaults)]
+#![feature(control_flow_enum)]
+#![feature(rustc_private)]
+#![feature(try_blocks)]
+#![recursion_limit = "256"]
+#![allow(rustc::potential_query_instability)]
+#![cfg_attr(not(bootstrap), deny(rustc::untranslatable_diagnostic))]
+#![cfg_attr(not(bootstrap), deny(rustc::diagnostic_outside_of_impl))]
+
+mod errors;
+
+use rustc_ast::MacroDef;
+use rustc_attr as attr;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::intern::Interned;
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
+use rustc_hir::intravisit::{self, Visitor};
+use rustc_hir::{AssocItemKind, HirIdSet, ItemId, Node, PatKind};
+use rustc_middle::bug;
+use rustc_middle::hir::nested_filter;
+use rustc_middle::middle::privacy::{AccessLevel, AccessLevels};
+use rustc_middle::span_bug;
+use rustc_middle::ty::abstract_const::{walk_abstract_const, AbstractConst, Node as ACNode};
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::subst::InternalSubsts;
+use rustc_middle::ty::{self, Const, DefIdTree, GenericParamDefKind};
+use rustc_middle::ty::{TraitRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_session::lint;
+use rustc_span::hygiene::Transparency;
+use rustc_span::symbol::{kw, Ident};
+use rustc_span::Span;
+
+use std::marker::PhantomData;
+use std::ops::ControlFlow;
+use std::{cmp, fmt, mem};
+
+use errors::{
+    FieldIsPrivate, FieldIsPrivateLabel, FromPrivateDependencyInPublicInterface, InPublicInterface,
+    InPublicInterfaceTraits, ItemIsPrivate, PrivateInPublicLint, UnnamedItemIsPrivate,
+};
+
+////////////////////////////////////////////////////////////////////////////////
+/// Generic infrastructure used to implement specific visitors below.
+////////////////////////////////////////////////////////////////////////////////
+
+/// Implemented to visit all `DefId`s in a type.
+/// Visiting `DefId`s is useful because visibilities and reachabilities are attached to them.
+/// The idea is to visit "all components of a type", as documented in
+/// <https://github.com/rust-lang/rfcs/blob/master/text/2145-type-privacy.md#how-to-determine-visibility-of-a-type>.
+/// The default type visitor (`TypeVisitor`) does most of the job, but it has some shortcomings.
+/// First, it doesn't have overridable `fn visit_trait_ref`, so we have to catch trait `DefId`s
+/// manually. Second, it doesn't visit some type components like signatures of fn types, or traits
+/// in `impl Trait`, see individual comments in `DefIdVisitorSkeleton::visit_ty`.
+trait DefIdVisitor<'tcx> {
+    type BreakTy = ();
+
+    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,
+        kind: &str,
+        descr: &dyn fmt::Display,
+    ) -> ControlFlow<Self::BreakTy>;
+
+    /// Not overridden, but used to actually visit types and traits.
+    fn skeleton(&mut self) -> DefIdVisitorSkeleton<'_, 'tcx, Self> {
+        DefIdVisitorSkeleton {
+            def_id_visitor: self,
+            visited_opaque_tys: Default::default(),
+            dummy: Default::default(),
+        }
+    }
+    fn visit(&mut self, ty_fragment: impl TypeVisitable<'tcx>) -> ControlFlow<Self::BreakTy> {
+        ty_fragment.visit_with(&mut self.skeleton())
+    }
+    fn visit_trait(&mut self, trait_ref: TraitRef<'tcx>) -> ControlFlow<Self::BreakTy> {
+        self.skeleton().visit_trait(trait_ref)
+    }
+    fn visit_projection_ty(
+        &mut self,
+        projection: ty::ProjectionTy<'tcx>,
+    ) -> ControlFlow<Self::BreakTy> {
+        self.skeleton().visit_projection_ty(projection)
+    }
+    fn visit_predicates(
+        &mut self,
+        predicates: ty::GenericPredicates<'tcx>,
+    ) -> ControlFlow<Self::BreakTy> {
+        self.skeleton().visit_predicates(predicates)
+    }
+}
+
+struct DefIdVisitorSkeleton<'v, 'tcx, V: ?Sized> {
+    def_id_visitor: &'v mut V,
+    visited_opaque_tys: FxHashSet<DefId>,
+    dummy: PhantomData<TyCtxt<'tcx>>,
+}
+
+impl<'tcx, V> DefIdVisitorSkeleton<'_, 'tcx, V>
+where
+    V: DefIdVisitor<'tcx> + ?Sized,
+{
+    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() { ControlFlow::CONTINUE } else { substs.visit_with(self) }
+    }
+
+    fn visit_projection_ty(
+        &mut self,
+        projection: ty::ProjectionTy<'tcx>,
+    ) -> ControlFlow<V::BreakTy> {
+        let (trait_ref, assoc_substs) =
+            projection.trait_ref_and_own_substs(self.def_id_visitor.tcx());
+        self.visit_trait(trait_ref)?;
+        if self.def_id_visitor.shallow() {
+            ControlFlow::CONTINUE
+        } else {
+            assoc_substs.iter().try_for_each(|subst| subst.visit_with(self))
+        }
+    }
+
+    fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ControlFlow<V::BreakTy> {
+        match predicate.kind().skip_binder() {
+            ty::PredicateKind::Trait(ty::TraitPredicate {
+                trait_ref,
+                constness: _,
+                polarity: _,
+            }) => self.visit_trait(trait_ref),
+            ty::PredicateKind::Projection(ty::ProjectionPredicate { projection_ty, term }) => {
+                term.visit_with(self)?;
+                self.visit_projection_ty(projection_ty)
+            }
+            ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _region)) => {
+                ty.visit_with(self)
+            }
+            ty::PredicateKind::RegionOutlives(..) => ControlFlow::CONTINUE,
+            ty::PredicateKind::ConstEvaluatable(uv)
+                if self.def_id_visitor.tcx().features().generic_const_exprs =>
+            {
+                let tcx = self.def_id_visitor.tcx();
+                if let Ok(Some(ct)) = AbstractConst::new(tcx, uv) {
+                    self.visit_abstract_const_expr(tcx, ct)?;
+                }
+                ControlFlow::CONTINUE
+            }
+            ty::PredicateKind::WellFormed(arg) => arg.visit_with(self),
+            _ => bug!("unexpected predicate: {:?}", predicate),
+        }
+    }
+
+    fn visit_abstract_const_expr(
+        &mut self,
+        tcx: TyCtxt<'tcx>,
+        ct: AbstractConst<'tcx>,
+    ) -> ControlFlow<V::BreakTy> {
+        walk_abstract_const(tcx, ct, |node| match node.root(tcx) {
+            ACNode::Leaf(leaf) => self.visit_const(leaf),
+            ACNode::Cast(_, _, ty) => self.visit_ty(ty),
+            ACNode::Binop(..) | ACNode::UnaryOp(..) | ACNode::FunctionCall(_, _) => {
+                ControlFlow::CONTINUE
+            }
+        })
+    }
+
+    fn visit_predicates(
+        &mut self,
+        predicates: ty::GenericPredicates<'tcx>,
+    ) -> ControlFlow<V::BreakTy> {
+        let ty::GenericPredicates { parent: _, predicates } = predicates;
+        predicates.iter().try_for_each(|&(predicate, _span)| self.visit_predicate(predicate))
+    }
+}
+
+impl<'tcx, V> TypeVisitor<'tcx> for DefIdVisitorSkeleton<'_, 'tcx, V>
+where
+    V: DefIdVisitor<'tcx> + ?Sized,
+{
+    type BreakTy = V::BreakTy;
+
+    fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<V::BreakTy> {
+        let tcx = self.def_id_visitor.tcx();
+        // InternalSubsts are not visited here because they are visited below
+        // in `super_visit_with`.
+        match *ty.kind() {
+            ty::Adt(ty::AdtDef(Interned(&ty::AdtDefData { did: def_id, .. }, _)), ..)
+            | ty::Foreign(def_id)
+            | ty::FnDef(def_id, ..)
+            | 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() {
+                    return ControlFlow::CONTINUE;
+                }
+                // Default type visitor doesn't visit signatures of fn types.
+                // Something like `fn() -> Priv {my_func}` is considered a private type even if
+                // `my_func` is public, so we need to visit signatures.
+                if let ty::FnDef(..) = ty.kind() {
+                    tcx.fn_sig(def_id).visit_with(self)?;
+                }
+                // Inherent static methods don't have self type in substs.
+                // Something like `fn() {my_method}` type of the method
+                // `impl Pub<Priv> { pub fn my_method() {} }` is considered a private type,
+                // so we need to visit the self type additionally.
+                if let Some(assoc_item) = tcx.opt_associated_item(def_id) {
+                    if let Some(impl_def_id) = assoc_item.impl_container(tcx) {
+                        tcx.type_of(impl_def_id).visit_with(self)?;
+                    }
+                }
+            }
+            ty::Projection(proj) => {
+                if self.def_id_visitor.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.
+                    // Ideally, associated types should be substituted in the same way as
+                    // free type aliases, but this isn't done yet.
+                    return ControlFlow::CONTINUE;
+                }
+                // This will also visit substs if necessary, so we don't need to recurse.
+                return self.visit_projection_ty(proj);
+            }
+            ty::Dynamic(predicates, ..) => {
+                // All traits in the list are considered the "primary" part of the type
+                // and are visited by shallow visitors.
+                for predicate in predicates {
+                    let trait_ref = match predicate.skip_binder() {
+                        ty::ExistentialPredicate::Trait(trait_ref) => trait_ref,
+                        ty::ExistentialPredicate::Projection(proj) => proj.trait_ref(tcx),
+                        ty::ExistentialPredicate::AutoTrait(def_id) => {
+                            ty::ExistentialTraitRef { def_id, substs: InternalSubsts::empty() }
+                        }
+                    };
+                    let ty::ExistentialTraitRef { def_id, substs: _ } = trait_ref;
+                    self.def_id_visitor.visit_def_id(def_id, "trait", &trait_ref)?;
+                }
+            }
+            ty::Opaque(def_id, ..) => {
+                // Skip repeated `Opaque`s to avoid infinite recursion.
+                if self.visited_opaque_tys.insert(def_id) {
+                    // The intent is to treat `impl Trait1 + Trait2` identically to
+                    // `dyn Trait1 + Trait2`. Therefore we ignore def-id of the opaque type itself
+                    // (it either has no visibility, or its visibility is insignificant, like
+                    // visibilities of type aliases) and recurse into bounds instead to go
+                    // through the trait list (default type visitor doesn't visit those traits).
+                    // All traits in the list are considered the "primary" part of the type
+                    // and are visited by shallow visitors.
+                    self.visit_predicates(ty::GenericPredicates {
+                        parent: None,
+                        predicates: tcx.explicit_item_bounds(def_id),
+                    })?;
+                }
+            }
+            // These types don't have their own def-ids (but may have subcomponents
+            // with def-ids that should be visited recursively).
+            ty::Bool
+            | ty::Char
+            | ty::Int(..)
+            | ty::Uint(..)
+            | ty::Float(..)
+            | ty::Str
+            | ty::Never
+            | ty::Array(..)
+            | ty::Slice(..)
+            | ty::Tuple(..)
+            | ty::RawPtr(..)
+            | ty::Ref(..)
+            | ty::FnPtr(..)
+            | ty::Param(..)
+            | ty::Error(_)
+            | ty::GeneratorWitness(..) => {}
+            ty::Bound(..) | ty::Placeholder(..) | ty::Infer(..) => {
+                bug!("unexpected type: {:?}", ty)
+            }
+        }
+
+        if self.def_id_visitor.shallow() {
+            ControlFlow::CONTINUE
+        } else {
+            ty.super_visit_with(self)
+        }
+    }
+
+    fn visit_const(&mut self, c: Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+        self.visit_ty(c.ty())?;
+        let tcx = self.def_id_visitor.tcx();
+        if let Ok(Some(ct)) = AbstractConst::from_const(tcx, c) {
+            self.visit_abstract_const_expr(tcx, ct)?;
+        }
+        ControlFlow::CONTINUE
+    }
+}
+
+fn min(vis1: ty::Visibility, vis2: ty::Visibility, tcx: TyCtxt<'_>) -> ty::Visibility {
+    if vis1.is_at_least(vis2, tcx) { vis2 } else { vis1 }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// Visitor used to determine impl visibility and reachability.
+////////////////////////////////////////////////////////////////////////////////
+
+struct FindMin<'a, 'tcx, VL: VisibilityLike> {
+    tcx: TyCtxt<'tcx>,
+    access_levels: &'a AccessLevels,
+    min: VL,
+}
+
+impl<'a, 'tcx, VL: VisibilityLike> DefIdVisitor<'tcx> for FindMin<'a, 'tcx, VL> {
+    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,
+        _kind: &str,
+        _descr: &dyn fmt::Display,
+    ) -> ControlFlow<Self::BreakTy> {
+        self.min = VL::new_min(self, def_id);
+        ControlFlow::CONTINUE
+    }
+}
+
+trait VisibilityLike: Sized {
+    const MAX: Self;
+    const SHALLOW: bool = false;
+    fn new_min(find: &FindMin<'_, '_, Self>, def_id: DefId) -> Self;
+
+    // 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(def_id: LocalDefId, tcx: TyCtxt<'_>, access_levels: &AccessLevels) -> Self {
+        let mut find = FindMin { tcx, access_levels, min: Self::MAX };
+        find.visit(tcx.type_of(def_id));
+        if let Some(trait_ref) = tcx.impl_trait_ref(def_id) {
+            find.visit_trait(trait_ref);
+        }
+        find.min
+    }
+}
+impl VisibilityLike for ty::Visibility {
+    const MAX: Self = ty::Visibility::Public;
+    fn new_min(find: &FindMin<'_, '_, Self>, def_id: DefId) -> Self {
+        min(find.tcx.visibility(def_id), find.min, find.tcx)
+    }
+}
+impl VisibilityLike for Option<AccessLevel> {
+    const MAX: Self = Some(AccessLevel::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: DefId) -> Self {
+        cmp::min(
+            if let Some(def_id) = def_id.as_local() {
+                find.access_levels.map.get(&def_id).copied()
+            } else {
+                Self::MAX
+            },
+            find.min,
+        )
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// The embargo visitor, used to determine the exports of the AST.
+////////////////////////////////////////////////////////////////////////////////
+
+struct EmbargoVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+
+    /// Accessibility levels for reachable nodes.
+    access_levels: AccessLevels,
+    /// A set of pairs corresponding to modules, where the first module is
+    /// reachable via a macro that's defined in the second module. This cannot
+    /// be represented as reachable because it can't handle the following case:
+    ///
+    /// pub mod n {                         // Should be `Public`
+    ///     pub(crate) mod p {              // Should *not* be accessible
+    ///         pub fn f() -> i32 { 12 }    // Must be `Reachable`
+    ///     }
+    /// }
+    /// pub macro m() {
+    ///     n::p::f()
+    /// }
+    macro_reachable: FxHashSet<(LocalDefId, LocalDefId)>,
+    /// Previous accessibility level; `None` means unreachable.
+    prev_level: Option<AccessLevel>,
+    /// Has something changed in the level map?
+    changed: bool,
+}
+
+struct ReachEverythingInTheInterfaceVisitor<'a, 'tcx> {
+    access_level: Option<AccessLevel>,
+    item_def_id: LocalDefId,
+    ev: &'a mut EmbargoVisitor<'tcx>,
+}
+
+impl<'tcx> EmbargoVisitor<'tcx> {
+    fn get(&self, def_id: LocalDefId) -> Option<AccessLevel> {
+        self.access_levels.map.get(&def_id).copied()
+    }
+
+    fn update_with_hir_id(
+        &mut self,
+        hir_id: hir::HirId,
+        level: Option<AccessLevel>,
+    ) -> Option<AccessLevel> {
+        let def_id = self.tcx.hir().local_def_id(hir_id);
+        self.update(def_id, level)
+    }
+
+    /// Updates node level and returns the updated level.
+    fn update(&mut self, def_id: LocalDefId, level: Option<AccessLevel>) -> Option<AccessLevel> {
+        let old_level = self.get(def_id);
+        // Accessibility levels can only grow.
+        if level > old_level {
+            self.access_levels.map.insert(def_id, level.unwrap());
+            self.changed = true;
+            level
+        } else {
+            old_level
+        }
+    }
+
+    fn reach(
+        &mut self,
+        def_id: LocalDefId,
+        access_level: Option<AccessLevel>,
+    ) -> ReachEverythingInTheInterfaceVisitor<'_, 'tcx> {
+        ReachEverythingInTheInterfaceVisitor {
+            access_level: cmp::min(access_level, Some(AccessLevel::Reachable)),
+            item_def_id: def_id,
+            ev: self,
+        }
+    }
+
+    // We have to make sure that the items that macros might reference
+    // are reachable, since they might be exported transitively.
+    fn update_reachability_from_macro(&mut self, local_def_id: LocalDefId, md: &MacroDef) {
+        // Non-opaque macros cannot make other items more accessible than they already are.
+
+        let hir_id = self.tcx.hir().local_def_id_to_hir_id(local_def_id);
+        let attrs = self.tcx.hir().attrs(hir_id);
+        if attr::find_transparency(attrs, md.macro_rules).0 != Transparency::Opaque {
+            return;
+        }
+
+        let macro_module_def_id = self.tcx.local_parent(local_def_id);
+        if self.tcx.opt_def_kind(macro_module_def_id) != Some(DefKind::Mod) {
+            // The macro's parent doesn't correspond to a `mod`, return early (#63164, #65252).
+            return;
+        }
+
+        if self.get(local_def_id).is_none() {
+            return;
+        }
+
+        // Since we are starting from an externally visible module,
+        // all the parents in the loop below are also guaranteed to be modules.
+        let mut module_def_id = macro_module_def_id;
+        loop {
+            let changed_reachability =
+                self.update_macro_reachable(module_def_id, macro_module_def_id);
+            if changed_reachability || module_def_id == CRATE_DEF_ID {
+                break;
+            }
+            module_def_id = self.tcx.local_parent(module_def_id);
+        }
+    }
+
+    /// Updates the item as being reachable through a macro defined in the given
+    /// module. Returns `true` if the level has changed.
+    fn update_macro_reachable(
+        &mut self,
+        module_def_id: LocalDefId,
+        defining_mod: LocalDefId,
+    ) -> bool {
+        if self.macro_reachable.insert((module_def_id, defining_mod)) {
+            self.update_macro_reachable_mod(module_def_id, defining_mod);
+            true
+        } else {
+            false
+        }
+    }
+
+    fn update_macro_reachable_mod(&mut self, module_def_id: LocalDefId, defining_mod: LocalDefId) {
+        let module = self.tcx.hir().get_module(module_def_id).0;
+        for item_id in module.item_ids {
+            let def_kind = self.tcx.def_kind(item_id.def_id);
+            let vis = self.tcx.visibility(item_id.def_id);
+            self.update_macro_reachable_def(item_id.def_id, def_kind, vis, defining_mod);
+        }
+        if let Some(exports) = self.tcx.module_reexports(module_def_id) {
+            for export in exports {
+                if export.vis.is_accessible_from(defining_mod.to_def_id(), self.tcx) {
+                    if let Res::Def(def_kind, def_id) = export.res {
+                        if let Some(def_id) = def_id.as_local() {
+                            let vis = self.tcx.visibility(def_id.to_def_id());
+                            self.update_macro_reachable_def(def_id, def_kind, vis, defining_mod);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    fn update_macro_reachable_def(
+        &mut self,
+        def_id: LocalDefId,
+        def_kind: DefKind,
+        vis: ty::Visibility,
+        module: LocalDefId,
+    ) {
+        let level = Some(AccessLevel::Reachable);
+        if vis.is_public() {
+            self.update(def_id, level);
+        }
+        match def_kind {
+            // No type privacy, so can be directly marked as reachable.
+            DefKind::Const | DefKind::Static(_) | DefKind::TraitAlias | DefKind::TyAlias => {
+                if vis.is_accessible_from(module.to_def_id(), self.tcx) {
+                    self.update(def_id, level);
+                }
+            }
+
+            // Hygiene isn't really implemented for `macro_rules!` macros at the
+            // moment. Accordingly, marking them as reachable is unwise. `macro` macros
+            // have normal hygiene, so we can treat them like other items without type
+            // privacy and mark them reachable.
+            DefKind::Macro(_) => {
+                let item = self.tcx.hir().expect_item(def_id);
+                if let hir::ItemKind::Macro(MacroDef { macro_rules: false, .. }, _) = item.kind {
+                    if vis.is_accessible_from(module.to_def_id(), self.tcx) {
+                        self.update(def_id, level);
+                    }
+                }
+            }
+
+            // We can't use a module name as the final segment of a path, except
+            // in use statements. Since re-export checking doesn't consider
+            // hygiene these don't need to be marked reachable. The contents of
+            // the module, however may be reachable.
+            DefKind::Mod => {
+                if vis.is_accessible_from(module.to_def_id(), self.tcx) {
+                    self.update_macro_reachable(def_id, module);
+                }
+            }
+
+            DefKind::Struct | DefKind::Union => {
+                // While structs and unions have type privacy, their fields do not.
+                if vis.is_public() {
+                    let item = self.tcx.hir().expect_item(def_id);
+                    if let hir::ItemKind::Struct(ref struct_def, _)
+                    | hir::ItemKind::Union(ref struct_def, _) = item.kind
+                    {
+                        for field in struct_def.fields() {
+                            let def_id = self.tcx.hir().local_def_id(field.hir_id);
+                            let field_vis = self.tcx.visibility(def_id);
+                            if field_vis.is_accessible_from(module.to_def_id(), self.tcx) {
+                                self.reach(def_id, level).ty();
+                            }
+                        }
+                    } else {
+                        bug!("item {:?} with DefKind {:?}", item, def_kind);
+                    }
+                }
+            }
+
+            // These have type privacy, so are not reachable unless they're
+            // public, or are not namespaced at all.
+            DefKind::AssocConst
+            | DefKind::AssocTy
+            | DefKind::ConstParam
+            | DefKind::Ctor(_, _)
+            | DefKind::Enum
+            | DefKind::ForeignTy
+            | DefKind::Fn
+            | DefKind::OpaqueTy
+            | DefKind::AssocFn
+            | DefKind::Trait
+            | DefKind::TyParam
+            | DefKind::Variant
+            | DefKind::LifetimeParam
+            | DefKind::ExternCrate
+            | DefKind::Use
+            | DefKind::ForeignMod
+            | DefKind::AnonConst
+            | DefKind::InlineConst
+            | DefKind::Field
+            | DefKind::GlobalAsm
+            | DefKind::Impl
+            | DefKind::Closure
+            | DefKind::Generator => (),
+        }
+    }
+}
+
+impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
+    type NestedFilter = nested_filter::All;
+
+    /// We want to visit items in the context of their containing
+    /// module and so forth, so supply a crate for doing a deep walk.
+    fn nested_visit_map(&mut self) -> Self::Map {
+        self.tcx.hir()
+    }
+
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        let item_level = match item.kind {
+            hir::ItemKind::Impl { .. } => {
+                let impl_level =
+                    Option::<AccessLevel>::of_impl(item.def_id, self.tcx, &self.access_levels);
+                self.update(item.def_id, impl_level)
+            }
+            _ => self.get(item.def_id),
+        };
+
+        // Update levels of nested things.
+        match item.kind {
+            hir::ItemKind::Enum(ref def, _) => {
+                for variant in def.variants {
+                    let variant_level = self.update_with_hir_id(variant.id, item_level);
+                    if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
+                        self.update_with_hir_id(ctor_hir_id, item_level);
+                    }
+                    for field in variant.data.fields() {
+                        self.update_with_hir_id(field.hir_id, variant_level);
+                    }
+                }
+            }
+            hir::ItemKind::Impl(ref impl_) => {
+                for impl_item_ref in impl_.items {
+                    if impl_.of_trait.is_some()
+                        || self.tcx.visibility(impl_item_ref.id.def_id) == ty::Visibility::Public
+                    {
+                        self.update(impl_item_ref.id.def_id, item_level);
+                    }
+                }
+            }
+            hir::ItemKind::Trait(.., trait_item_refs) => {
+                for trait_item_ref in trait_item_refs {
+                    self.update(trait_item_ref.id.def_id, item_level);
+                }
+            }
+            hir::ItemKind::Struct(ref def, _) | hir::ItemKind::Union(ref def, _) => {
+                if let Some(ctor_hir_id) = def.ctor_hir_id() {
+                    self.update_with_hir_id(ctor_hir_id, item_level);
+                }
+                for field in def.fields() {
+                    let def_id = self.tcx.hir().local_def_id(field.hir_id);
+                    let vis = self.tcx.visibility(def_id);
+                    if vis.is_public() {
+                        self.update_with_hir_id(field.hir_id, item_level);
+                    }
+                }
+            }
+            hir::ItemKind::Macro(ref macro_def, _) => {
+                self.update_reachability_from_macro(item.def_id, macro_def);
+            }
+            hir::ItemKind::ForeignMod { items, .. } => {
+                for foreign_item in items {
+                    if self.tcx.visibility(foreign_item.id.def_id) == ty::Visibility::Public {
+                        self.update(foreign_item.id.def_id, item_level);
+                    }
+                }
+            }
+
+            hir::ItemKind::OpaqueTy(..)
+            | hir::ItemKind::Use(..)
+            | hir::ItemKind::Static(..)
+            | hir::ItemKind::Const(..)
+            | hir::ItemKind::GlobalAsm(..)
+            | hir::ItemKind::TyAlias(..)
+            | hir::ItemKind::Mod(..)
+            | hir::ItemKind::TraitAlias(..)
+            | hir::ItemKind::Fn(..)
+            | hir::ItemKind::ExternCrate(..) => {}
+        }
+
+        // Mark all items in interfaces of reachable items as reachable.
+        match item.kind {
+            // The interface is empty.
+            hir::ItemKind::Macro(..) | hir::ItemKind::ExternCrate(..) => {}
+            // All nested items are checked by `visit_item`.
+            hir::ItemKind::Mod(..) => {}
+            // Handled in the access level of in rustc_resolve
+            hir::ItemKind::Use(..) => {}
+            // The interface is empty.
+            hir::ItemKind::GlobalAsm(..) => {}
+            hir::ItemKind::OpaqueTy(..) => {
+                // HACK(jynelson): trying to infer the type of `impl trait` breaks `async-std` (and `pub async fn` in general)
+                // Since rustdoc never needs to do codegen and doesn't care about link-time reachability,
+                // mark this as unreachable.
+                // See https://github.com/rust-lang/rust/issues/75100
+                if !self.tcx.sess.opts.actually_rustdoc {
+                    // FIXME: This is some serious pessimization intended to workaround deficiencies
+                    // in the reachability pass (`middle/reachable.rs`). Types are marked as link-time
+                    // reachable if they are returned via `impl Trait`, even from private functions.
+                    let exist_level =
+                        cmp::max(item_level, Some(AccessLevel::ReachableFromImplTrait));
+                    self.reach(item.def_id, exist_level).generics().predicates().ty();
+                }
+            }
+            // Visit everything.
+            hir::ItemKind::Const(..)
+            | hir::ItemKind::Static(..)
+            | hir::ItemKind::Fn(..)
+            | hir::ItemKind::TyAlias(..) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates().ty();
+                }
+            }
+            hir::ItemKind::Trait(.., trait_item_refs) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates();
+
+                    for trait_item_ref in trait_item_refs {
+                        let tcx = self.tcx;
+                        let mut reach = self.reach(trait_item_ref.id.def_id, item_level);
+                        reach.generics().predicates();
+
+                        if trait_item_ref.kind == AssocItemKind::Type
+                            && !tcx.impl_defaultness(trait_item_ref.id.def_id).has_value()
+                        {
+                            // No type to visit.
+                        } else {
+                            reach.ty();
+                        }
+                    }
+                }
+            }
+            hir::ItemKind::TraitAlias(..) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates();
+                }
+            }
+            // Visit everything except for private impl items.
+            hir::ItemKind::Impl(ref impl_) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates().ty().trait_ref();
+
+                    for impl_item_ref in impl_.items {
+                        let impl_item_level = self.get(impl_item_ref.id.def_id);
+                        if impl_item_level.is_some() {
+                            self.reach(impl_item_ref.id.def_id, impl_item_level)
+                                .generics()
+                                .predicates()
+                                .ty();
+                        }
+                    }
+                }
+            }
+
+            // Visit everything, but enum variants have their own levels.
+            hir::ItemKind::Enum(ref def, _) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates();
+                }
+                for variant in def.variants {
+                    let variant_level = self.get(self.tcx.hir().local_def_id(variant.id));
+                    if variant_level.is_some() {
+                        for field in variant.data.fields() {
+                            self.reach(self.tcx.hir().local_def_id(field.hir_id), variant_level)
+                                .ty();
+                        }
+                        // Corner case: if the variant is reachable, but its
+                        // enum is not, make the enum reachable as well.
+                        self.reach(item.def_id, variant_level).ty();
+                    }
+                    if let Some(hir_id) = variant.data.ctor_hir_id() {
+                        let ctor_def_id = self.tcx.hir().local_def_id(hir_id);
+                        let ctor_level = self.get(ctor_def_id);
+                        if ctor_level.is_some() {
+                            self.reach(item.def_id, ctor_level).ty();
+                        }
+                    }
+                }
+            }
+            // Visit everything, but foreign items have their own levels.
+            hir::ItemKind::ForeignMod { items, .. } => {
+                for foreign_item in items {
+                    let foreign_item_level = self.get(foreign_item.id.def_id);
+                    if foreign_item_level.is_some() {
+                        self.reach(foreign_item.id.def_id, foreign_item_level)
+                            .generics()
+                            .predicates()
+                            .ty();
+                    }
+                }
+            }
+            // Visit everything except for private fields.
+            hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
+                if item_level.is_some() {
+                    self.reach(item.def_id, item_level).generics().predicates();
+                    for field in struct_def.fields() {
+                        let def_id = self.tcx.hir().local_def_id(field.hir_id);
+                        let field_level = self.get(def_id);
+                        if field_level.is_some() {
+                            self.reach(def_id, field_level).ty();
+                        }
+                    }
+                }
+                if let Some(hir_id) = struct_def.ctor_hir_id() {
+                    let ctor_def_id = self.tcx.hir().local_def_id(hir_id);
+                    let ctor_level = self.get(ctor_def_id);
+                    if ctor_level.is_some() {
+                        self.reach(item.def_id, ctor_level).ty();
+                    }
+                }
+            }
+        }
+
+        let orig_level = mem::replace(&mut self.prev_level, item_level);
+        intravisit::walk_item(self, item);
+        self.prev_level = orig_level;
+    }
+
+    fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
+        // Blocks can have public items, for example impls, but they always
+        // start as completely private regardless of publicity of a function,
+        // constant, type, field, etc., in which this block resides.
+        let orig_level = mem::replace(&mut self.prev_level, None);
+        intravisit::walk_block(self, b);
+        self.prev_level = orig_level;
+    }
+}
+
+impl ReachEverythingInTheInterfaceVisitor<'_, '_> {
+    fn generics(&mut self) -> &mut Self {
+        for param in &self.ev.tcx.generics_of(self.item_def_id).params {
+            match param.kind {
+                GenericParamDefKind::Lifetime => {}
+                GenericParamDefKind::Type { has_default, .. } => {
+                    if has_default {
+                        self.visit(self.ev.tcx.type_of(param.def_id));
+                    }
+                }
+                GenericParamDefKind::Const { has_default } => {
+                    self.visit(self.ev.tcx.type_of(param.def_id));
+                    if has_default {
+                        self.visit(self.ev.tcx.const_param_default(param.def_id));
+                    }
+                }
+            }
+        }
+        self
+    }
+
+    fn predicates(&mut self) -> &mut Self {
+        self.visit_predicates(self.ev.tcx.predicates_of(self.item_def_id));
+        self
+    }
+
+    fn ty(&mut self) -> &mut Self {
+        self.visit(self.ev.tcx.type_of(self.item_def_id));
+        self
+    }
+
+    fn trait_ref(&mut self) -> &mut Self {
+        if let Some(trait_ref) = self.ev.tcx.impl_trait_ref(self.item_def_id) {
+            self.visit_trait(trait_ref);
+        }
+        self
+    }
+}
+
+impl<'tcx> DefIdVisitor<'tcx> for ReachEverythingInTheInterfaceVisitor<'_, 'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.ev.tcx
+    }
+    fn visit_def_id(
+        &mut self,
+        def_id: DefId,
+        _kind: &str,
+        _descr: &dyn fmt::Display,
+    ) -> ControlFlow<Self::BreakTy> {
+        if let Some(def_id) = def_id.as_local() {
+            if let (ty::Visibility::Public, _) | (_, Some(AccessLevel::ReachableFromImplTrait)) =
+                (self.tcx().visibility(def_id.to_def_id()), self.access_level)
+            {
+                self.ev.update(def_id, self.access_level);
+            }
+        }
+        ControlFlow::CONTINUE
+    }
+}
+
+//////////////////////////////////////////////////////////////////////////////////////
+/// Name privacy visitor, checks privacy and reports violations.
+/// Most of name privacy checks are performed during the main resolution phase,
+/// or later in type checking when field accesses and associated items are resolved.
+/// This pass performs remaining checks for fields in struct expressions and patterns.
+//////////////////////////////////////////////////////////////////////////////////////
+
+struct NamePrivacyVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>,
+    current_item: LocalDefId,
+}
+
+impl<'tcx> NamePrivacyVisitor<'tcx> {
+    /// Gets the type-checking results for the current body.
+    /// As this will ICE if called outside bodies, only call when working with
+    /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
+    #[track_caller]
+    fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
+        self.maybe_typeck_results
+            .expect("`NamePrivacyVisitor::typeck_results` called outside of body")
+    }
+
+    // Checks that a field in a struct constructor (expression or pattern) is accessible.
+    fn check_field(
+        &mut self,
+        use_ctxt: Span,        // syntax context of the field name at the use site
+        span: Span,            // span of the field pattern, e.g., `x: 0`
+        def: ty::AdtDef<'tcx>, // definition of the struct or enum
+        field: &'tcx ty::FieldDef,
+        in_update_syntax: bool,
+    ) {
+        if def.is_enum() {
+            return;
+        }
+
+        // definition of the field
+        let ident = Ident::new(kw::Empty, use_ctxt);
+        let hir_id = self.tcx.hir().local_def_id_to_hir_id(self.current_item);
+        let def_id = self.tcx.adjust_ident_and_get_scope(ident, def.did(), hir_id).1;
+        if !field.vis.is_accessible_from(def_id, self.tcx) {
+            self.tcx.sess.emit_err(FieldIsPrivate {
+                span,
+                field_name: field.name,
+                variant_descr: def.variant_descr(),
+                def_path_str: self.tcx.def_path_str(def.did()),
+                label: if in_update_syntax {
+                    FieldIsPrivateLabel::IsUpdateSyntax { span, field_name: field.name }
+                } else {
+                    FieldIsPrivateLabel::Other { span }
+                },
+            });
+        }
+    }
+}
+
+impl<'tcx> Visitor<'tcx> for NamePrivacyVisitor<'tcx> {
+    type NestedFilter = nested_filter::All;
+
+    /// We want to visit items in the context of their containing
+    /// module and so forth, so supply a crate for doing a deep walk.
+    fn nested_visit_map(&mut self) -> Self::Map {
+        self.tcx.hir()
+    }
+
+    fn visit_mod(&mut self, _m: &'tcx hir::Mod<'tcx>, _s: Span, _n: hir::HirId) {
+        // Don't visit nested modules, since we run a separate visitor walk
+        // for each module in `privacy_access_levels`
+    }
+
+    fn visit_nested_body(&mut self, body: hir::BodyId) {
+        let old_maybe_typeck_results =
+            self.maybe_typeck_results.replace(self.tcx.typeck_body(body));
+        let body = self.tcx.hir().body(body);
+        self.visit_body(body);
+        self.maybe_typeck_results = old_maybe_typeck_results;
+    }
+
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        let orig_current_item = mem::replace(&mut self.current_item, item.def_id);
+        intravisit::walk_item(self, item);
+        self.current_item = orig_current_item;
+    }
+
+    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+        if let hir::ExprKind::Struct(qpath, fields, ref base) = expr.kind {
+            let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
+            let adt = self.typeck_results().expr_ty(expr).ty_adt_def().unwrap();
+            let variant = adt.variant_of_res(res);
+            if let Some(base) = *base {
+                // If the expression uses FRU we need to make sure all the unmentioned fields
+                // are checked for privacy (RFC 736). Rather than computing the set of
+                // unmentioned fields, just check them all.
+                for (vf_index, variant_field) in variant.fields.iter().enumerate() {
+                    let field = fields.iter().find(|f| {
+                        self.tcx.field_index(f.hir_id, self.typeck_results()) == vf_index
+                    });
+                    let (use_ctxt, span) = match field {
+                        Some(field) => (field.ident.span, field.span),
+                        None => (base.span, base.span),
+                    };
+                    self.check_field(use_ctxt, span, adt, variant_field, true);
+                }
+            } else {
+                for field in fields {
+                    let use_ctxt = field.ident.span;
+                    let index = self.tcx.field_index(field.hir_id, self.typeck_results());
+                    self.check_field(use_ctxt, field.span, adt, &variant.fields[index], false);
+                }
+            }
+        }
+
+        intravisit::walk_expr(self, expr);
+    }
+
+    fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
+        if let PatKind::Struct(ref qpath, fields, _) = pat.kind {
+            let res = self.typeck_results().qpath_res(qpath, pat.hir_id);
+            let adt = self.typeck_results().pat_ty(pat).ty_adt_def().unwrap();
+            let variant = adt.variant_of_res(res);
+            for field in fields {
+                let use_ctxt = field.ident.span;
+                let index = self.tcx.field_index(field.hir_id, self.typeck_results());
+                self.check_field(use_ctxt, field.span, adt, &variant.fields[index], false);
+            }
+        }
+
+        intravisit::walk_pat(self, pat);
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////
+/// Type privacy visitor, checks types for privacy and reports violations.
+/// Both explicitly written types and inferred types of expressions and patterns are checked.
+/// Checks are performed on "semantic" types regardless of names and their hygiene.
+////////////////////////////////////////////////////////////////////////////////////////////
+
+struct TypePrivacyVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>,
+    current_item: LocalDefId,
+    span: Span,
+}
+
+impl<'tcx> TypePrivacyVisitor<'tcx> {
+    /// Gets the type-checking results for the current body.
+    /// As this will ICE if called outside bodies, only call when working with
+    /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
+    #[track_caller]
+    fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
+        self.maybe_typeck_results
+            .expect("`TypePrivacyVisitor::typeck_results` called outside of body")
+    }
+
+    fn item_is_accessible(&self, did: DefId) -> bool {
+        self.tcx.visibility(did).is_accessible_from(self.current_item.to_def_id(), self.tcx)
+    }
+
+    // Take node-id of an expression or pattern and check its type for privacy.
+    fn check_expr_pat_type(&mut self, id: hir::HirId, span: Span) -> bool {
+        self.span = span;
+        let typeck_results = self.typeck_results();
+        let result: ControlFlow<()> = try {
+            self.visit(typeck_results.node_type(id))?;
+            self.visit(typeck_results.node_substs(id))?;
+            if let Some(adjustments) = typeck_results.adjustments().get(id) {
+                adjustments.iter().try_for_each(|adjustment| self.visit(adjustment.target))?;
+            }
+        };
+        result.is_break()
+    }
+
+    fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display) -> bool {
+        let is_error = !self.item_is_accessible(def_id);
+        if is_error {
+            self.tcx.sess.emit_err(ItemIsPrivate { span: self.span, kind, descr: descr.into() });
+        }
+        is_error
+    }
+}
+
+impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
+    type NestedFilter = nested_filter::All;
+
+    /// We want to visit items in the context of their containing
+    /// module and so forth, so supply a crate for doing a deep walk.
+    fn nested_visit_map(&mut self) -> Self::Map {
+        self.tcx.hir()
+    }
+
+    fn visit_mod(&mut self, _m: &'tcx hir::Mod<'tcx>, _s: Span, _n: hir::HirId) {
+        // Don't visit nested modules, since we run a separate visitor walk
+        // for each module in `privacy_access_levels`
+    }
+
+    fn visit_nested_body(&mut self, body: hir::BodyId) {
+        let old_maybe_typeck_results =
+            self.maybe_typeck_results.replace(self.tcx.typeck_body(body));
+        let body = self.tcx.hir().body(body);
+        self.visit_body(body);
+        self.maybe_typeck_results = old_maybe_typeck_results;
+    }
+
+    fn visit_generic_arg(&mut self, generic_arg: &'tcx hir::GenericArg<'tcx>) {
+        match generic_arg {
+            hir::GenericArg::Type(t) => self.visit_ty(t),
+            hir::GenericArg::Infer(inf) => self.visit_infer(inf),
+            hir::GenericArg::Lifetime(_) | hir::GenericArg::Const(_) => {}
+        }
+    }
+
+    fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
+        self.span = hir_ty.span;
+        if let Some(typeck_results) = self.maybe_typeck_results {
+            // Types in bodies.
+            if self.visit(typeck_results.node_type(hir_ty.hir_id)).is_break() {
+                return;
+            }
+        } else {
+            // Types in signatures.
+            // FIXME: This is very ineffective. Ideally each HIR type should be converted
+            // into a semantic type only once and the result should be cached somehow.
+            if self.visit(rustc_typeck::hir_ty_to_ty(self.tcx, hir_ty)).is_break() {
+                return;
+            }
+        }
+
+        intravisit::walk_ty(self, hir_ty);
+    }
+
+    fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
+        self.span = inf.span;
+        if let Some(typeck_results) = self.maybe_typeck_results {
+            if let Some(ty) = typeck_results.node_type_opt(inf.hir_id) {
+                if self.visit(ty).is_break() {
+                    return;
+                }
+            } else {
+                // We don't do anything for const infers here.
+            }
+        } else {
+            bug!("visit_infer without typeck_results");
+        }
+        intravisit::walk_inf(self, inf);
+    }
+
+    fn visit_trait_ref(&mut self, trait_ref: &'tcx hir::TraitRef<'tcx>) {
+        self.span = trait_ref.path.span;
+        if self.maybe_typeck_results.is_none() {
+            // Avoid calling `hir_trait_to_predicates` in bodies, it will ICE.
+            // The traits' privacy in bodies is already checked as a part of trait object types.
+            let bounds = rustc_typeck::hir_trait_to_predicates(
+                self.tcx,
+                trait_ref,
+                // NOTE: This isn't really right, but the actual type doesn't matter here. It's
+                // just required by `ty::TraitRef`.
+                self.tcx.types.never,
+            );
+
+            for (trait_predicate, _, _) in bounds.trait_bounds {
+                if self.visit_trait(trait_predicate.skip_binder()).is_break() {
+                    return;
+                }
+            }
+
+            for (poly_predicate, _) in bounds.projection_bounds {
+                let pred = poly_predicate.skip_binder();
+                let poly_pred_term = self.visit(pred.term);
+                if poly_pred_term.is_break()
+                    || self.visit_projection_ty(pred.projection_ty).is_break()
+                {
+                    return;
+                }
+            }
+        }
+
+        intravisit::walk_trait_ref(self, trait_ref);
+    }
+
+    // Check types of expressions
+    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+        if self.check_expr_pat_type(expr.hir_id, expr.span) {
+            // Do not check nested expressions if the error already happened.
+            return;
+        }
+        match expr.kind {
+            hir::ExprKind::Assign(_, rhs, _) | hir::ExprKind::Match(rhs, ..) => {
+                // Do not report duplicate errors for `x = y` and `match x { ... }`.
+                if self.check_expr_pat_type(rhs.hir_id, rhs.span) {
+                    return;
+                }
+            }
+            hir::ExprKind::MethodCall(segment, ..) => {
+                // Method calls have to be checked specially.
+                self.span = segment.ident.span;
+                if let Some(def_id) = self.typeck_results().type_dependent_def_id(expr.hir_id) {
+                    if self.visit(self.tcx.type_of(def_id)).is_break() {
+                        return;
+                    }
+                } else {
+                    self.tcx
+                        .sess
+                        .delay_span_bug(expr.span, "no type-dependent def for method call");
+                }
+            }
+            _ => {}
+        }
+
+        intravisit::walk_expr(self, expr);
+    }
+
+    // Prohibit access to associated items with insufficient nominal visibility.
+    //
+    // Additionally, until better reachability analysis for macros 2.0 is available,
+    // we prohibit access to private statics from other crates, this allows to give
+    // more code internal visibility at link time. (Access to private functions
+    // is already prohibited by type privacy for function types.)
+    fn visit_qpath(&mut self, qpath: &'tcx hir::QPath<'tcx>, id: hir::HirId, span: Span) {
+        let def = match qpath {
+            hir::QPath::Resolved(_, path) => match path.res {
+                Res::Def(kind, def_id) => Some((kind, def_id)),
+                _ => None,
+            },
+            hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
+                .maybe_typeck_results
+                .and_then(|typeck_results| typeck_results.type_dependent_def(id)),
+        };
+        let def = def.filter(|(kind, _)| {
+            matches!(
+                kind,
+                DefKind::AssocFn | DefKind::AssocConst | DefKind::AssocTy | DefKind::Static(_)
+            )
+        });
+        if let Some((kind, def_id)) = def {
+            let is_local_static =
+                if let DefKind::Static(_) = kind { def_id.is_local() } else { false };
+            if !self.item_is_accessible(def_id) && !is_local_static {
+                let sess = self.tcx.sess;
+                let sm = sess.source_map();
+                let name = match qpath {
+                    hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => {
+                        sm.span_to_snippet(qpath.span()).ok()
+                    }
+                    hir::QPath::TypeRelative(_, segment) => Some(segment.ident.to_string()),
+                };
+                let kind = kind.descr(def_id);
+                let _ = match name {
+                    Some(name) => {
+                        sess.emit_err(ItemIsPrivate { span, kind, descr: (&name).into() })
+                    }
+                    None => sess.emit_err(UnnamedItemIsPrivate { span, kind }),
+                };
+                return;
+            }
+        }
+
+        intravisit::walk_qpath(self, qpath, id, span);
+    }
+
+    // Check types of patterns.
+    fn visit_pat(&mut self, pattern: &'tcx hir::Pat<'tcx>) {
+        if self.check_expr_pat_type(pattern.hir_id, pattern.span) {
+            // Do not check nested patterns if the error already happened.
+            return;
+        }
+
+        intravisit::walk_pat(self, pattern);
+    }
+
+    fn visit_local(&mut self, local: &'tcx hir::Local<'tcx>) {
+        if let Some(init) = local.init {
+            if self.check_expr_pat_type(init.hir_id, init.span) {
+                // Do not report duplicate errors for `let x = y`.
+                return;
+            }
+        }
+
+        intravisit::walk_local(self, local);
+    }
+
+    // Check types in item interfaces.
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        let orig_current_item = mem::replace(&mut self.current_item, item.def_id);
+        let old_maybe_typeck_results = self.maybe_typeck_results.take();
+        intravisit::walk_item(self, item);
+        self.maybe_typeck_results = old_maybe_typeck_results;
+        self.current_item = orig_current_item;
+    }
+}
+
+impl<'tcx> DefIdVisitor<'tcx> for TypePrivacyVisitor<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+    fn visit_def_id(
+        &mut self,
+        def_id: DefId,
+        kind: &str,
+        descr: &dyn fmt::Display,
+    ) -> ControlFlow<Self::BreakTy> {
+        if self.check_def_id(def_id, kind, descr) {
+            ControlFlow::BREAK
+        } else {
+            ControlFlow::CONTINUE
+        }
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+/// Obsolete visitors for checking for private items in public interfaces.
+/// These visitors are supposed to be kept in frozen state and produce an
+/// "old error node set". For backward compatibility the new visitor reports
+/// warnings instead of hard errors when the erroneous node is not in this old set.
+///////////////////////////////////////////////////////////////////////////////
+
+struct ObsoleteVisiblePrivateTypesVisitor<'a, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    access_levels: &'a AccessLevels,
+    in_variant: bool,
+    // Set of errors produced by this obsolete visitor.
+    old_error_set: HirIdSet,
+}
+
+struct ObsoleteCheckTypeForPrivatenessVisitor<'a, 'b, 'tcx> {
+    inner: &'a ObsoleteVisiblePrivateTypesVisitor<'b, 'tcx>,
+    /// Whether the type refers to private types.
+    contains_private: bool,
+    /// Whether we've recurred at all (i.e., if we're pointing at the
+    /// first type on which `visit_ty` was called).
+    at_outer_type: bool,
+    /// Whether that first type is a public path.
+    outer_type_is_public_path: bool,
+}
+
+impl<'a, 'tcx> ObsoleteVisiblePrivateTypesVisitor<'a, 'tcx> {
+    fn path_is_private_type(&self, path: &hir::Path<'_>) -> bool {
+        let did = match path.res {
+            Res::PrimTy(..) | Res::SelfTy { .. } | Res::Err => return false,
+            res => res.def_id(),
+        };
+
+        // A path can only be private if:
+        // it's in this crate...
+        if let Some(did) = did.as_local() {
+            // .. and it corresponds to a private type in the AST (this returns
+            // `None` for type parameters).
+            match self.tcx.hir().find(self.tcx.hir().local_def_id_to_hir_id(did)) {
+                Some(Node::Item(_)) => !self.tcx.visibility(did).is_public(),
+                Some(_) | None => false,
+            }
+        } else {
+            false
+        }
+    }
+
+    fn trait_is_public(&self, trait_id: LocalDefId) -> bool {
+        // FIXME: this would preferably be using `exported_items`, but all
+        // traits are exported currently (see `EmbargoVisitor.exported_trait`).
+        self.access_levels.is_public(trait_id)
+    }
+
+    fn check_generic_bound(&mut self, bound: &hir::GenericBound<'_>) {
+        if let hir::GenericBound::Trait(ref trait_ref, _) = *bound {
+            if self.path_is_private_type(trait_ref.trait_ref.path) {
+                self.old_error_set.insert(trait_ref.trait_ref.hir_ref_id);
+            }
+        }
+    }
+
+    fn item_is_public(&self, def_id: LocalDefId) -> bool {
+        self.access_levels.is_reachable(def_id) || self.tcx.visibility(def_id).is_public()
+    }
+}
+
+impl<'a, 'b, 'tcx, 'v> Visitor<'v> for ObsoleteCheckTypeForPrivatenessVisitor<'a, 'b, 'tcx> {
+    fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
+        match generic_arg {
+            hir::GenericArg::Type(t) => self.visit_ty(t),
+            hir::GenericArg::Infer(inf) => self.visit_ty(&inf.to_ty()),
+            hir::GenericArg::Lifetime(_) | hir::GenericArg::Const(_) => {}
+        }
+    }
+
+    fn visit_ty(&mut self, ty: &hir::Ty<'_>) {
+        if let hir::TyKind::Path(hir::QPath::Resolved(_, path)) = ty.kind {
+            if self.inner.path_is_private_type(path) {
+                self.contains_private = true;
+                // Found what we're looking for, so let's stop working.
+                return;
+            }
+        }
+        if let hir::TyKind::Path(_) = ty.kind {
+            if self.at_outer_type {
+                self.outer_type_is_public_path = true;
+            }
+        }
+        self.at_outer_type = false;
+        intravisit::walk_ty(self, ty)
+    }
+
+    // Don't want to recurse into `[, .. expr]`.
+    fn visit_expr(&mut self, _: &hir::Expr<'_>) {}
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for ObsoleteVisiblePrivateTypesVisitor<'a, 'tcx> {
+    type NestedFilter = nested_filter::All;
+
+    /// We want to visit items in the context of their containing
+    /// module and so forth, so supply a crate for doing a deep walk.
+    fn nested_visit_map(&mut self) -> Self::Map {
+        self.tcx.hir()
+    }
+
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        match item.kind {
+            // Contents of a private mod can be re-exported, so we need
+            // to check internals.
+            hir::ItemKind::Mod(_) => {}
+
+            // An `extern {}` doesn't introduce a new privacy
+            // namespace (the contents have their own privacies).
+            hir::ItemKind::ForeignMod { .. } => {}
+
+            hir::ItemKind::Trait(.., bounds, _) => {
+                if !self.trait_is_public(item.def_id) {
+                    return;
+                }
+
+                for bound in bounds.iter() {
+                    self.check_generic_bound(bound)
+                }
+            }
+
+            // Impls need some special handling to try to offer useful
+            // error messages without (too many) false positives
+            // (i.e., we could just return here to not check them at
+            // all, or some worse estimation of whether an impl is
+            // publicly visible).
+            hir::ItemKind::Impl(ref impl_) => {
+                // `impl [... for] Private` is never visible.
+                let self_contains_private;
+                // `impl [... for] Public<...>`, but not `impl [... for]
+                // Vec<Public>` or `(Public,)`, etc.
+                let self_is_public_path;
+
+                // Check the properties of the `Self` type:
+                {
+                    let mut visitor = ObsoleteCheckTypeForPrivatenessVisitor {
+                        inner: self,
+                        contains_private: false,
+                        at_outer_type: true,
+                        outer_type_is_public_path: false,
+                    };
+                    visitor.visit_ty(impl_.self_ty);
+                    self_contains_private = visitor.contains_private;
+                    self_is_public_path = visitor.outer_type_is_public_path;
+                }
+
+                // Miscellaneous info about the impl:
+
+                // `true` iff this is `impl Private for ...`.
+                let not_private_trait = impl_.of_trait.as_ref().map_or(
+                    true, // no trait counts as public trait
+                    |tr| {
+                        if let Some(def_id) = tr.path.res.def_id().as_local() {
+                            self.trait_is_public(def_id)
+                        } else {
+                            true // external traits must be public
+                        }
+                    },
+                );
+
+                // `true` iff this is a trait impl or at least one method is public.
+                //
+                // `impl Public { $( fn ...() {} )* }` is not visible.
+                //
+                // This is required over just using the methods' privacy
+                // directly because we might have `impl<T: Foo<Private>> ...`,
+                // and we shouldn't warn about the generics if all the methods
+                // are private (because `T` won't be visible externally).
+                let trait_or_some_public_method = impl_.of_trait.is_some()
+                    || impl_.items.iter().any(|impl_item_ref| {
+                        let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
+                        match impl_item.kind {
+                            hir::ImplItemKind::Const(..) | hir::ImplItemKind::Fn(..) => {
+                                self.access_levels.is_reachable(impl_item_ref.id.def_id)
+                            }
+                            hir::ImplItemKind::TyAlias(_) => false,
+                        }
+                    });
+
+                if !self_contains_private && not_private_trait && trait_or_some_public_method {
+                    intravisit::walk_generics(self, &impl_.generics);
+
+                    match impl_.of_trait {
+                        None => {
+                            for impl_item_ref in impl_.items {
+                                // This is where we choose whether to walk down
+                                // further into the impl to check its items. We
+                                // should only walk into public items so that we
+                                // don't erroneously report errors for private
+                                // types in private items.
+                                let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
+                                match impl_item.kind {
+                                    hir::ImplItemKind::Const(..) | hir::ImplItemKind::Fn(..)
+                                        if self.item_is_public(impl_item.def_id) =>
+                                    {
+                                        intravisit::walk_impl_item(self, impl_item)
+                                    }
+                                    hir::ImplItemKind::TyAlias(..) => {
+                                        intravisit::walk_impl_item(self, impl_item)
+                                    }
+                                    _ => {}
+                                }
+                            }
+                        }
+                        Some(ref tr) => {
+                            // Any private types in a trait impl fall into three
+                            // categories.
+                            // 1. mentioned in the trait definition
+                            // 2. mentioned in the type params/generics
+                            // 3. mentioned in the associated types of the impl
+                            //
+                            // Those in 1. can only occur if the trait is in
+                            // this crate and will have been warned about on the
+                            // trait definition (there's no need to warn twice
+                            // so we don't check the methods).
+                            //
+                            // Those in 2. are warned via walk_generics and this
+                            // call here.
+                            intravisit::walk_path(self, tr.path);
+
+                            // Those in 3. are warned with this call.
+                            for impl_item_ref in impl_.items {
+                                let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
+                                if let hir::ImplItemKind::TyAlias(ty) = impl_item.kind {
+                                    self.visit_ty(ty);
+                                }
+                            }
+                        }
+                    }
+                } else if impl_.of_trait.is_none() && self_is_public_path {
+                    // `impl Public<Private> { ... }`. Any public static
+                    // methods will be visible as `Public::foo`.
+                    let mut found_pub_static = false;
+                    for impl_item_ref in impl_.items {
+                        if self.access_levels.is_reachable(impl_item_ref.id.def_id)
+                            || self.tcx.visibility(impl_item_ref.id.def_id)
+                                == ty::Visibility::Public
+                        {
+                            let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
+                            match impl_item_ref.kind {
+                                AssocItemKind::Const => {
+                                    found_pub_static = true;
+                                    intravisit::walk_impl_item(self, impl_item);
+                                }
+                                AssocItemKind::Fn { has_self: false } => {
+                                    found_pub_static = true;
+                                    intravisit::walk_impl_item(self, impl_item);
+                                }
+                                _ => {}
+                            }
+                        }
+                    }
+                    if found_pub_static {
+                        intravisit::walk_generics(self, &impl_.generics)
+                    }
+                }
+                return;
+            }
+
+            // `type ... = ...;` can contain private types, because
+            // we're introducing a new name.
+            hir::ItemKind::TyAlias(..) => return,
+
+            // Not at all public, so we don't care.
+            _ if !self.item_is_public(item.def_id) => {
+                return;
+            }
+
+            _ => {}
+        }
+
+        // We've carefully constructed it so that if we're here, then
+        // any `visit_ty`'s will be called on things that are in
+        // public signatures, i.e., things that we're interested in for
+        // this visitor.
+        intravisit::walk_item(self, item);
+    }
+
+    fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
+        for predicate in generics.predicates {
+            match predicate {
+                hir::WherePredicate::BoundPredicate(bound_pred) => {
+                    for bound in bound_pred.bounds.iter() {
+                        self.check_generic_bound(bound)
+                    }
+                }
+                hir::WherePredicate::RegionPredicate(_) => {}
+                hir::WherePredicate::EqPredicate(eq_pred) => {
+                    self.visit_ty(eq_pred.rhs_ty);
+                }
+            }
+        }
+    }
+
+    fn visit_foreign_item(&mut self, item: &'tcx hir::ForeignItem<'tcx>) {
+        if self.access_levels.is_reachable(item.def_id) {
+            intravisit::walk_foreign_item(self, item)
+        }
+    }
+
+    fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
+        if let hir::TyKind::Path(hir::QPath::Resolved(_, path)) = t.kind {
+            if self.path_is_private_type(path) {
+                self.old_error_set.insert(t.hir_id);
+            }
+        }
+        intravisit::walk_ty(self, t)
+    }
+
+    fn visit_variant(
+        &mut self,
+        v: &'tcx hir::Variant<'tcx>,
+        g: &'tcx hir::Generics<'tcx>,
+        item_id: hir::HirId,
+    ) {
+        if self.access_levels.is_reachable(self.tcx.hir().local_def_id(v.id)) {
+            self.in_variant = true;
+            intravisit::walk_variant(self, v, g, item_id);
+            self.in_variant = false;
+        }
+    }
+
+    fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
+        let def_id = self.tcx.hir().local_def_id(s.hir_id);
+        let vis = self.tcx.visibility(def_id);
+        if vis.is_public() || self.in_variant {
+            intravisit::walk_field_def(self, s);
+        }
+    }
+
+    // We don't need to introspect into these at all: an
+    // expression/block context can't possibly contain exported things.
+    // (Making them no-ops stops us from traversing the whole AST without
+    // having to be super careful about our `walk_...` calls above.)
+    fn visit_block(&mut self, _: &'tcx hir::Block<'tcx>) {}
+    fn visit_expr(&mut self, _: &'tcx hir::Expr<'tcx>) {}
+}
+
+///////////////////////////////////////////////////////////////////////////////
+/// SearchInterfaceForPrivateItemsVisitor traverses an item's interface and
+/// finds any private components in it.
+/// PrivateItemsInPublicInterfacesVisitor ensures there are no private types
+/// and traits in public interfaces.
+///////////////////////////////////////////////////////////////////////////////
+
+struct SearchInterfaceForPrivateItemsVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    item_def_id: LocalDefId,
+    /// The visitor checks that each component type is at least this visible.
+    required_visibility: ty::Visibility,
+    has_old_errors: bool,
+    in_assoc_ty: bool,
+}
+
+impl SearchInterfaceForPrivateItemsVisitor<'_> {
+    fn generics(&mut self) -> &mut Self {
+        for param in &self.tcx.generics_of(self.item_def_id).params {
+            match param.kind {
+                GenericParamDefKind::Lifetime => {}
+                GenericParamDefKind::Type { has_default, .. } => {
+                    if has_default {
+                        self.visit(self.tcx.type_of(param.def_id));
+                    }
+                }
+                // FIXME(generic_const_exprs): May want to look inside const here
+                GenericParamDefKind::Const { .. } => {
+                    self.visit(self.tcx.type_of(param.def_id));
+                }
+            }
+        }
+        self
+    }
+
+    fn predicates(&mut self) -> &mut Self {
+        // N.B., we use `explicit_predicates_of` and not `predicates_of`
+        // because we don't want to report privacy errors due to where
+        // clauses that the compiler inferred. We only want to
+        // consider the ones that the user wrote. This is important
+        // for the inferred outlives rules; see
+        // `src/test/ui/rfc-2093-infer-outlives/privacy.rs`.
+        self.visit_predicates(self.tcx.explicit_predicates_of(self.item_def_id));
+        self
+    }
+
+    fn bounds(&mut self) -> &mut Self {
+        self.visit_predicates(ty::GenericPredicates {
+            parent: None,
+            predicates: self.tcx.explicit_item_bounds(self.item_def_id),
+        });
+        self
+    }
+
+    fn ty(&mut self) -> &mut Self {
+        self.visit(self.tcx.type_of(self.item_def_id));
+        self
+    }
+
+    fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display) -> bool {
+        if self.leaks_private_dep(def_id) {
+            self.tcx.emit_spanned_lint(
+                lint::builtin::EXPORTED_PRIVATE_DEPENDENCIES,
+                self.tcx.hir().local_def_id_to_hir_id(self.item_def_id),
+                self.tcx.def_span(self.item_def_id.to_def_id()),
+                FromPrivateDependencyInPublicInterface {
+                    kind,
+                    descr: descr.into(),
+                    krate: self.tcx.crate_name(def_id.krate),
+                },
+            );
+        }
+
+        let hir_id = match def_id.as_local() {
+            Some(def_id) => self.tcx.hir().local_def_id_to_hir_id(def_id),
+            None => return false,
+        };
+
+        let vis = self.tcx.visibility(def_id);
+        if !vis.is_at_least(self.required_visibility, self.tcx) {
+            let vis_descr = match vis {
+                ty::Visibility::Public => "public",
+                ty::Visibility::Invisible => "private",
+                ty::Visibility::Restricted(vis_def_id) => {
+                    if vis_def_id == self.tcx.parent_module(hir_id).to_def_id() {
+                        "private"
+                    } else if vis_def_id.is_top_level_module() {
+                        "crate-private"
+                    } else {
+                        "restricted"
+                    }
+                }
+            };
+            let span = self.tcx.def_span(self.item_def_id.to_def_id());
+            if self.has_old_errors
+                || self.in_assoc_ty
+                || self.tcx.resolutions(()).has_pub_restricted
+            {
+                let vis_span = self.tcx.def_span(def_id);
+                if kind == "trait" {
+                    self.tcx.sess.emit_err(InPublicInterfaceTraits {
+                        span,
+                        vis_descr,
+                        kind,
+                        descr: descr.into(),
+                        vis_span,
+                    });
+                } else {
+                    self.tcx.sess.emit_err(InPublicInterface {
+                        span,
+                        vis_descr,
+                        kind,
+                        descr: descr.into(),
+                        vis_span,
+                    });
+                }
+            } else {
+                self.tcx.emit_spanned_lint(
+                    lint::builtin::PRIVATE_IN_PUBLIC,
+                    hir_id,
+                    span,
+                    PrivateInPublicLint { vis_descr, kind, descr: descr.into() },
+                );
+            }
+        }
+
+        false
+    }
+
+    /// An item is 'leaked' from a private dependency if all
+    /// of the following are true:
+    /// 1. It's contained within a public type
+    /// 2. It comes from a private crate
+    fn leaks_private_dep(&self, item_id: DefId) -> bool {
+        let ret = self.required_visibility.is_public() && self.tcx.is_private_dep(item_id.krate);
+
+        tracing::debug!("leaks_private_dep(item_id={:?})={}", item_id, ret);
+        ret
+    }
+}
+
+impl<'tcx> DefIdVisitor<'tcx> for SearchInterfaceForPrivateItemsVisitor<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+    fn visit_def_id(
+        &mut self,
+        def_id: DefId,
+        kind: &str,
+        descr: &dyn fmt::Display,
+    ) -> ControlFlow<Self::BreakTy> {
+        if self.check_def_id(def_id, kind, descr) {
+            ControlFlow::BREAK
+        } else {
+            ControlFlow::CONTINUE
+        }
+    }
+}
+
+struct PrivateItemsInPublicInterfacesChecker<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    old_error_set_ancestry: LocalDefIdSet,
+}
+
+impl<'tcx> PrivateItemsInPublicInterfacesChecker<'tcx> {
+    fn check(
+        &self,
+        def_id: LocalDefId,
+        required_visibility: ty::Visibility,
+    ) -> SearchInterfaceForPrivateItemsVisitor<'tcx> {
+        SearchInterfaceForPrivateItemsVisitor {
+            tcx: self.tcx,
+            item_def_id: def_id,
+            required_visibility,
+            has_old_errors: self.old_error_set_ancestry.contains(&def_id),
+            in_assoc_ty: false,
+        }
+    }
+
+    fn check_assoc_item(
+        &self,
+        def_id: LocalDefId,
+        assoc_item_kind: AssocItemKind,
+        vis: ty::Visibility,
+    ) {
+        let mut check = self.check(def_id, vis);
+
+        let (check_ty, is_assoc_ty) = match assoc_item_kind {
+            AssocItemKind::Const | AssocItemKind::Fn { .. } => (true, false),
+            AssocItemKind::Type => (self.tcx.impl_defaultness(def_id).has_value(), true),
+        };
+        check.in_assoc_ty = is_assoc_ty;
+        check.generics().predicates();
+        if check_ty {
+            check.ty();
+        }
+    }
+
+    pub fn check_item(&mut self, id: ItemId) {
+        let tcx = self.tcx;
+        let item_visibility = tcx.visibility(id.def_id);
+        let def_kind = tcx.def_kind(id.def_id);
+
+        match def_kind {
+            DefKind::Const | DefKind::Static(_) | DefKind::Fn | DefKind::TyAlias => {
+                self.check(id.def_id, item_visibility).generics().predicates().ty();
+            }
+            DefKind::OpaqueTy => {
+                // `ty()` for opaque types is the underlying type,
+                // it's not a part of interface, so we skip it.
+                self.check(id.def_id, item_visibility).generics().bounds();
+            }
+            DefKind::Trait => {
+                let item = tcx.hir().item(id);
+                if let hir::ItemKind::Trait(.., trait_item_refs) = item.kind {
+                    self.check(item.def_id, item_visibility).generics().predicates();
+
+                    for trait_item_ref in trait_item_refs {
+                        self.check_assoc_item(
+                            trait_item_ref.id.def_id,
+                            trait_item_ref.kind,
+                            item_visibility,
+                        );
+
+                        if let AssocItemKind::Type = trait_item_ref.kind {
+                            self.check(trait_item_ref.id.def_id, item_visibility).bounds();
+                        }
+                    }
+                }
+            }
+            DefKind::TraitAlias => {
+                self.check(id.def_id, item_visibility).generics().predicates();
+            }
+            DefKind::Enum => {
+                let item = tcx.hir().item(id);
+                if let hir::ItemKind::Enum(ref def, _) = item.kind {
+                    self.check(item.def_id, item_visibility).generics().predicates();
+
+                    for variant in def.variants {
+                        for field in variant.data.fields() {
+                            self.check(self.tcx.hir().local_def_id(field.hir_id), item_visibility)
+                                .ty();
+                        }
+                    }
+                }
+            }
+            // Subitems of foreign modules have their own publicity.
+            DefKind::ForeignMod => {
+                let item = tcx.hir().item(id);
+                if let hir::ItemKind::ForeignMod { items, .. } = item.kind {
+                    for foreign_item in items {
+                        let vis = tcx.visibility(foreign_item.id.def_id);
+                        self.check(foreign_item.id.def_id, vis).generics().predicates().ty();
+                    }
+                }
+            }
+            // Subitems of structs and unions have their own publicity.
+            DefKind::Struct | DefKind::Union => {
+                let item = tcx.hir().item(id);
+                if let hir::ItemKind::Struct(ref struct_def, _)
+                | hir::ItemKind::Union(ref struct_def, _) = item.kind
+                {
+                    self.check(item.def_id, item_visibility).generics().predicates();
+
+                    for field in struct_def.fields() {
+                        let def_id = tcx.hir().local_def_id(field.hir_id);
+                        let field_visibility = tcx.visibility(def_id);
+                        self.check(def_id, min(item_visibility, field_visibility, tcx)).ty();
+                    }
+                }
+            }
+            // An inherent impl is public when its type is public
+            // Subitems of inherent impls have their own publicity.
+            // A trait impl is public when both its type and its trait are public
+            // Subitems of trait impls have inherited publicity.
+            DefKind::Impl => {
+                let item = tcx.hir().item(id);
+                if let hir::ItemKind::Impl(ref impl_) = item.kind {
+                    let impl_vis = ty::Visibility::of_impl(item.def_id, tcx, &Default::default());
+                    // 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
+                    if impl_.of_trait.is_none() {
+                        self.check(item.def_id, impl_vis).generics().predicates();
+                    }
+                    for impl_item_ref in impl_.items {
+                        let impl_item_vis = if impl_.of_trait.is_none() {
+                            min(tcx.visibility(impl_item_ref.id.def_id), impl_vis, tcx)
+                        } else {
+                            impl_vis
+                        };
+                        self.check_assoc_item(
+                            impl_item_ref.id.def_id,
+                            impl_item_ref.kind,
+                            impl_item_vis,
+                        );
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        visibility,
+        privacy_access_levels,
+        check_private_in_public,
+        check_mod_privacy,
+        ..*providers
+    };
+}
+
+fn visibility(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Visibility {
+    let def_id = def_id.expect_local();
+    match tcx.resolutions(()).visibilities.get(&def_id) {
+        Some(vis) => *vis,
+        None => {
+            let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+            match tcx.hir().get(hir_id) {
+                // Unique types created for closures participate in type privacy checking.
+                // They have visibilities inherited from the module they are defined in.
+                Node::Expr(hir::Expr { kind: hir::ExprKind::Closure{..}, .. })
+                // - AST lowering creates dummy `use` items which don't
+                //   get their entries in the resolver's visibility table.
+                // - AST lowering also creates opaque type items with inherited visibilities.
+                //   Visibility on them should have no effect, but to avoid the visibility
+                //   query failing on some items, we provide it for opaque types as well.
+                | Node::Item(hir::Item {
+                    kind: hir::ItemKind::Use(_, hir::UseKind::ListStem) | hir::ItemKind::OpaqueTy(..),
+                    ..
+                }) => ty::Visibility::Restricted(tcx.parent_module(hir_id).to_def_id()),
+                // Visibilities of trait impl items are inherited from their traits
+                // and are not filled in resolve.
+                Node::ImplItem(impl_item) => {
+                    match tcx.hir().get_by_def_id(tcx.hir().get_parent_item(hir_id)) {
+                        Node::Item(hir::Item {
+                            kind: hir::ItemKind::Impl(hir::Impl { of_trait: Some(tr), .. }),
+                            ..
+                        }) => tr.path.res.opt_def_id().map_or_else(
+                            || {
+                                tcx.sess.delay_span_bug(tr.path.span, "trait without a def-id");
+                                ty::Visibility::Public
+                            },
+                            |def_id| tcx.visibility(def_id),
+                        ),
+                        _ => span_bug!(impl_item.span, "the parent is not a trait impl"),
+                    }
+                }
+                _ => span_bug!(
+                    tcx.def_span(def_id),
+                    "visibility table unexpectedly missing a def-id: {:?}",
+                    def_id,
+                ),
+            }
+        }
+    }
+}
+
+fn check_mod_privacy(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
+    // Check privacy of names not checked in previous compilation stages.
+    let mut visitor =
+        NamePrivacyVisitor { tcx, maybe_typeck_results: None, current_item: module_def_id };
+    let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
+
+    intravisit::walk_mod(&mut visitor, module, hir_id);
+
+    // Check privacy of explicitly written types and traits as well as
+    // inferred types of expressions and patterns.
+    let mut visitor =
+        TypePrivacyVisitor { tcx, maybe_typeck_results: None, current_item: module_def_id, span };
+    intravisit::walk_mod(&mut visitor, module, hir_id);
+}
+
+fn privacy_access_levels(tcx: TyCtxt<'_>, (): ()) -> &AccessLevels {
+    // Build up a set of all exported items in the AST. This is a set of all
+    // items which are reachable from external crates based on visibility.
+    let mut visitor = EmbargoVisitor {
+        tcx,
+        access_levels: tcx.resolutions(()).access_levels.clone(),
+        macro_reachable: Default::default(),
+        prev_level: Some(AccessLevel::Public),
+        changed: false,
+    };
+
+    loop {
+        tcx.hir().walk_toplevel_module(&mut visitor);
+        if visitor.changed {
+            visitor.changed = false;
+        } else {
+            break;
+        }
+    }
+
+    tcx.arena.alloc(visitor.access_levels)
+}
+
+fn check_private_in_public(tcx: TyCtxt<'_>, (): ()) {
+    let access_levels = tcx.privacy_access_levels(());
+
+    let mut visitor = ObsoleteVisiblePrivateTypesVisitor {
+        tcx,
+        access_levels,
+        in_variant: false,
+        old_error_set: Default::default(),
+    };
+    tcx.hir().walk_toplevel_module(&mut visitor);
+
+    let mut old_error_set_ancestry = HirIdSet::default();
+    for mut id in visitor.old_error_set.iter().copied() {
+        loop {
+            if !old_error_set_ancestry.insert(id) {
+                break;
+            }
+            let parent = tcx.hir().get_parent_node(id);
+            if parent == id {
+                break;
+            }
+            id = parent;
+        }
+    }
+
+    // Check for private types and traits in public interfaces.
+    let mut checker = PrivateItemsInPublicInterfacesChecker {
+        tcx,
+        // Only definition IDs are ever searched in `old_error_set_ancestry`,
+        // so we can filter away all non-definition IDs at this point.
+        old_error_set_ancestry: old_error_set_ancestry
+            .into_iter()
+            .filter_map(|hir_id| tcx.hir().opt_local_def_id(hir_id))
+            .collect(),
+    };
+
+    for id in tcx.hir().items() {
+        checker.check_item(id);
+    }
+}