Overhaul the `intravisit::Map` trait.

First of all, note that `Map` has three different relevant meanings.
- The `intravisit::Map` trait.
- The `map::Map` struct.
- The `NestedFilter::Map` associated type.

The `intravisit::Map` trait is impl'd twice.
- For `!`, where the methods are all unreachable.
- For `map::Map`, which gets HIR stuff from the `TyCtxt`.

As part of getting rid of `map::Map`, this commit changes `impl
intravisit::Map for map::Map` to `impl intravisit::Map for TyCtxt`. It's
fairly straightforward except various things are renamed, because the
existing names would no longer have made sense.

- `trait intravisit::Map` becomes `trait intravisit::HirTyCtxt`, so named
  because it gets some HIR stuff from a `TyCtxt`.
- `NestedFilter::Map` assoc type becomes `NestedFilter::MaybeTyCtxt`,
  because it's always `!` or `TyCtxt`.
- `Visitor::nested_visit_map` becomes `Visitor::maybe_tcx`.

I deliberately made the new trait and associated type names different to
avoid the old `type Map: Map` situation, which I found confusing. We now
have `type MaybeTyCtxt: HirTyCtxt`.

29 files changed, 135 insertions, 134 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 4428d2246a1..59c76cb7f2b 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -348,13 +348,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             expr: Option<&'hir hir::Expr<'hir>>,
             pat: Option<&'hir hir::Pat<'hir>>,
             parent_pat: Option<&'hir hir::Pat<'hir>>,
-            hir: rustc_middle::hir::map::Map<'hir>,
+            tcx: TyCtxt<'hir>,
         }
         impl<'hir> Visitor<'hir> for ExpressionFinder<'hir> {
             type NestedFilter = OnlyBodies;
 
-            fn nested_visit_map(&mut self) -> Self::Map {
-                self.hir
+            fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+                self.tcx
             }
 
             fn visit_expr(&mut self, e: &'hir hir::Expr<'hir>) {
@@ -396,7 +396,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 expr: None,
                 pat: None,
                 parent_pat: None,
-                hir,
+                tcx: self.infcx.tcx,
             };
             finder.visit_expr(expr);
             if let Some(span) = span
@@ -2455,7 +2455,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let body_expr = tcx.hir_body(body_id).value;
 
         struct ClosureFinder<'hir> {
-            hir: rustc_middle::hir::map::Map<'hir>,
+            tcx: TyCtxt<'hir>,
             borrow_span: Span,
             res: Option<(&'hir hir::Expr<'hir>, &'hir hir::Closure<'hir>)>,
             /// The path expression with the `borrow_span` span
@@ -2464,8 +2464,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         impl<'hir> Visitor<'hir> for ClosureFinder<'hir> {
             type NestedFilter = OnlyBodies;
 
-            fn nested_visit_map(&mut self) -> Self::Map {
-                self.hir
+            fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+                self.tcx
             }
 
             fn visit_expr(&mut self, ex: &'hir hir::Expr<'hir>) {
@@ -2491,7 +2491,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
         // Find the closure that most tightly wraps `capture_kind_span`
         let mut finder =
-            ClosureFinder { hir, borrow_span: capture_kind_span, res: None, error_path: None };
+            ClosureFinder { tcx, borrow_span: capture_kind_span, res: None, error_path: None };
         finder.visit_expr(body_expr);
         let Some((closure_expr, closure)) = finder.res else { return };
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index 976d14bb245..a88b27f2476 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -256,8 +256,8 @@ impl<'tcx> BorrowExplanation<'tcx> {
 
                         impl<'hir> rustc_hir::intravisit::Visitor<'hir> for FindLetExpr<'hir> {
                             type NestedFilter = rustc_middle::hir::nested_filter::OnlyBodies;
-                            fn nested_visit_map(&mut self) -> Self::Map {
-                                self.tcx.hir()
+                            fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+                                self.tcx
                             }
                             fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) {
                                 if let hir::ExprKind::If(cond, _conseq, _alt)
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
index c5449952f99..38f22473edf 100644
--- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -7,7 +7,7 @@ use rustc_hir::intravisit::Visitor;
 use rustc_hir::{self as hir, CaptureBy, ExprKind, HirId, Node};
 use rustc_middle::bug;
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_mir_dataflow::move_paths::{LookupResult, MovePathIndex};
 use rustc_span::{BytePos, ExpnKind, MacroKind, Span};
 use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
@@ -690,7 +690,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         /// make it bind by reference instead (if possible)
         struct BindingFinder<'tcx> {
             typeck_results: &'tcx ty::TypeckResults<'tcx>,
-            hir: rustc_middle::hir::map::Map<'tcx>,
+            tcx: TyCtxt<'tcx>,
             /// Input: the span of the pattern we're finding bindings in
             pat_span: Span,
             /// Input: the spans of the bindings we're providing suggestions for
@@ -709,8 +709,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         impl<'tcx> Visitor<'tcx> for BindingFinder<'tcx> {
             type NestedFilter = rustc_middle::hir::nested_filter::OnlyBodies;
 
-            fn nested_visit_map(&mut self) -> Self::Map {
-                self.hir
+            fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+                self.tcx
             }
 
             fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) -> Self::Result {
@@ -782,7 +782,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let typeck_results = self.infcx.tcx.typeck(self.mir_def_id());
         let mut finder = BindingFinder {
             typeck_results,
-            hir,
+            tcx: self.infcx.tcx,
             pat_span,
             binding_spans,
             found_pat: false,
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index f57d1a5cc2c..949f8daa4dc 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -18,7 +18,7 @@
 //!    within one another.
 //!    - Example: Examine each expression to look for its type and do some check or other.
 //!    - How: Implement `intravisit::Visitor` and override the `NestedFilter` type to
-//!      `nested_filter::OnlyBodies` (and implement `nested_visit_map`), and use
+//!      `nested_filter::OnlyBodies` (and implement `maybe_tcx`), and use
 //!      `tcx.hir().visit_all_item_likes_in_crate(&mut visitor)`. Within your
 //!      `intravisit::Visitor` impl, implement methods like `visit_expr()` (don't forget to invoke
 //!      `intravisit::walk_expr()` to keep walking the subparts).
@@ -30,7 +30,7 @@
 //!    - Example: Lifetime resolution, which wants to bring lifetimes declared on the
 //!      impl into scope while visiting the impl-items, and then back out again.
 //!    - How: Implement `intravisit::Visitor` and override the `NestedFilter` type to
-//!      `nested_filter::All` (and implement `nested_visit_map`). Walk your crate with
+//!      `nested_filter::All` (and implement `maybe_tcx`). Walk your crate with
 //!      `tcx.hir().walk_toplevel_module(visitor)` invoked on `tcx.hir().krate()`.
 //!    - Pro: Visitor methods for any kind of HIR node, not just item-like things.
 //!    - Pro: Preserves nesting information
@@ -106,41 +106,43 @@ impl<'a> FnKind<'a> {
     }
 }
 
-/// An abstract representation of the HIR `rustc_middle::hir::map::Map`.
-pub trait Map<'hir> {
+/// HIR things retrievable from `TyCtxt`, avoiding an explicit dependence on
+/// `TyCtxt`. The only impls are for `!` (where these functions are never
+/// called) and `TyCtxt` (in `rustc_middle`).
+pub trait HirTyCtxt<'hir> {
     /// Retrieves the `Node` corresponding to `id`.
     fn hir_node(&self, hir_id: HirId) -> Node<'hir>;
-    fn body(&self, id: BodyId) -> &'hir Body<'hir>;
-    fn item(&self, id: ItemId) -> &'hir Item<'hir>;
-    fn trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir>;
-    fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir>;
-    fn foreign_item(&self, id: ForeignItemId) -> &'hir ForeignItem<'hir>;
+    fn hir_body(&self, id: BodyId) -> &'hir Body<'hir>;
+    fn hir_item(&self, id: ItemId) -> &'hir Item<'hir>;
+    fn hir_trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir>;
+    fn hir_impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir>;
+    fn hir_foreign_item(&self, id: ForeignItemId) -> &'hir ForeignItem<'hir>;
 }
 
-// Used when no map is actually available, forcing manual implementation of nested visitors.
-impl<'hir> Map<'hir> for ! {
+// Used when no tcx is actually available, forcing manual implementation of nested visitors.
+impl<'hir> HirTyCtxt<'hir> for ! {
     fn hir_node(&self, _: HirId) -> Node<'hir> {
         unreachable!();
     }
-    fn body(&self, _: BodyId) -> &'hir Body<'hir> {
+    fn hir_body(&self, _: BodyId) -> &'hir Body<'hir> {
         unreachable!();
     }
-    fn item(&self, _: ItemId) -> &'hir Item<'hir> {
+    fn hir_item(&self, _: ItemId) -> &'hir Item<'hir> {
         unreachable!();
     }
-    fn trait_item(&self, _: TraitItemId) -> &'hir TraitItem<'hir> {
+    fn hir_trait_item(&self, _: TraitItemId) -> &'hir TraitItem<'hir> {
         unreachable!();
     }
-    fn impl_item(&self, _: ImplItemId) -> &'hir ImplItem<'hir> {
+    fn hir_impl_item(&self, _: ImplItemId) -> &'hir ImplItem<'hir> {
         unreachable!();
     }
-    fn foreign_item(&self, _: ForeignItemId) -> &'hir ForeignItem<'hir> {
+    fn hir_foreign_item(&self, _: ForeignItemId) -> &'hir ForeignItem<'hir> {
         unreachable!();
     }
 }
 
 pub mod nested_filter {
-    use super::Map;
+    use super::HirTyCtxt;
 
     /// Specifies what nested things a visitor wants to visit. By "nested
     /// things", we are referring to bits of HIR that are not directly embedded
@@ -155,7 +157,7 @@ pub mod nested_filter {
     /// See the comments at [`rustc_hir::intravisit`] for more details on the overall
     /// visit strategy.
     pub trait NestedFilter<'hir> {
-        type Map: Map<'hir>;
+        type MaybeTyCtxt: HirTyCtxt<'hir>;
 
         /// Whether the visitor visits nested "item-like" things.
         /// E.g., item, impl-item.
@@ -171,10 +173,10 @@ pub mod nested_filter {
     ///
     /// Use this if you are only walking some particular kind of tree
     /// (i.e., a type, or fn signature) and you don't want to thread a
-    /// HIR map around.
+    /// `tcx` around.
     pub struct None(());
     impl NestedFilter<'_> for None {
-        type Map = !;
+        type MaybeTyCtxt = !;
         const INTER: bool = false;
         const INTRA: bool = false;
     }
@@ -199,18 +201,18 @@ use nested_filter::NestedFilter;
 /// to monitor future changes to `Visitor` in case a new method with a
 /// new default implementation gets introduced.)
 pub trait Visitor<'v>: Sized {
-    // This type should not be overridden, it exists for convenient usage as `Self::Map`.
-    type Map: Map<'v> = <Self::NestedFilter as NestedFilter<'v>>::Map;
+    // This type should not be overridden, it exists for convenient usage as `Self::MaybeTyCtxt`.
+    type MaybeTyCtxt: HirTyCtxt<'v> = <Self::NestedFilter as NestedFilter<'v>>::MaybeTyCtxt;
 
     ///////////////////////////////////////////////////////////////////////////
     // Nested items.
 
     /// Override this type to control which nested HIR are visited; see
     /// [`NestedFilter`] for details. If you override this type, you
-    /// must also override [`nested_visit_map`](Self::nested_visit_map).
+    /// must also override [`maybe_tcx`](Self::maybe_tcx).
     ///
     /// **If for some reason you want the nested behavior, but don't
-    /// have a `Map` at your disposal:** then override the
+    /// have a `tcx` at your disposal:** then override the
     /// `visit_nested_XXX` methods. If a new `visit_nested_XXX` variant is
     /// added in the future, it will cause a panic which can be detected
     /// and fixed appropriately.
@@ -222,9 +224,9 @@ pub trait Visitor<'v>: Sized {
 
     /// If `type NestedFilter` is set to visit nested items, this method
     /// must also be overridden to provide a map to retrieve nested items.
-    fn nested_visit_map(&mut self) -> Self::Map {
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
         panic!(
-            "nested_visit_map must be implemented or consider using \
+            "maybe_tcx must be implemented or consider using \
             `type NestedFilter = nested_filter::None` (the default)"
         );
     }
@@ -236,10 +238,10 @@ pub trait Visitor<'v>: Sized {
     /// "deep" visit patterns described at
     /// [`rustc_hir::intravisit`]. The only reason to override
     /// this method is if you want a nested pattern but cannot supply a
-    /// [`Map`]; see `nested_visit_map` for advice.
+    /// `TyCtxt`; see `maybe_tcx` for advice.
     fn visit_nested_item(&mut self, id: ItemId) -> Self::Result {
         if Self::NestedFilter::INTER {
-            let item = self.nested_visit_map().item(id);
+            let item = self.maybe_tcx().hir_item(id);
             try_visit!(self.visit_item(item));
         }
         Self::Result::output()
@@ -250,7 +252,7 @@ pub trait Visitor<'v>: Sized {
     /// method.
     fn visit_nested_trait_item(&mut self, id: TraitItemId) -> Self::Result {
         if Self::NestedFilter::INTER {
-            let item = self.nested_visit_map().trait_item(id);
+            let item = self.maybe_tcx().hir_trait_item(id);
             try_visit!(self.visit_trait_item(item));
         }
         Self::Result::output()
@@ -261,7 +263,7 @@ pub trait Visitor<'v>: Sized {
     /// method.
     fn visit_nested_impl_item(&mut self, id: ImplItemId) -> Self::Result {
         if Self::NestedFilter::INTER {
-            let item = self.nested_visit_map().impl_item(id);
+            let item = self.maybe_tcx().hir_impl_item(id);
             try_visit!(self.visit_impl_item(item));
         }
         Self::Result::output()
@@ -272,7 +274,7 @@ pub trait Visitor<'v>: Sized {
     /// method.
     fn visit_nested_foreign_item(&mut self, id: ForeignItemId) -> Self::Result {
         if Self::NestedFilter::INTER {
-            let item = self.nested_visit_map().foreign_item(id);
+            let item = self.maybe_tcx().hir_foreign_item(id);
             try_visit!(self.visit_foreign_item(item));
         }
         Self::Result::output()
@@ -283,7 +285,7 @@ pub trait Visitor<'v>: Sized {
     /// `Self::NestedFilter`.
     fn visit_nested_body(&mut self, id: BodyId) -> Self::Result {
         if Self::NestedFilter::INTRA {
-            let body = self.nested_visit_map().body(id);
+            let body = self.maybe_tcx().hir_body(id);
             try_visit!(self.visit_body(body));
         }
         Self::Result::output()
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 0d33aaa5d84..bc0fd4b705d 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -435,8 +435,8 @@ fn best_definition_site_of_opaque<'tcx>(
     impl<'tcx> intravisit::Visitor<'tcx> for TaitConstraintLocator<'tcx> {
         type NestedFilter = nested_filter::All;
         type Result = ControlFlow<(Span, LocalDefId)>;
-        fn nested_visit_map(&mut self) -> Self::Map {
-            self.tcx.hir()
+        fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+            self.tcx
         }
         fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) -> Self::Result {
             if let hir::ExprKind::Closure(closure) = ex.kind {
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 6b430df8ed2..75ea207a06b 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -277,8 +277,8 @@ fn reject_placeholder_type_signatures_in_item<'tcx>(
 impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs
index b4ba4d11221..63c445fa6a3 100644
--- a/compiler/rustc_hir_analysis/src/collect/dump.rs
+++ b/compiler/rustc_hir_analysis/src/collect/dump.rs
@@ -63,8 +63,8 @@ pub(crate) fn def_parents(tcx: TyCtxt<'_>) {
             impl<'tcx> intravisit::Visitor<'tcx> for AnonConstFinder<'tcx> {
                 type NestedFilter = nested_filter::All;
 
-                fn nested_visit_map(&mut self) -> Self::Map {
-                    self.tcx.hir()
+                fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+                    self.tcx
                 }
 
                 fn visit_anon_const(&mut self, c: &'tcx rustc_hir::AnonConst) {
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index 6bf0498a8b0..5a8a2f1fe28 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -422,8 +422,8 @@ enum NonLifetimeBinderAllowed {
 impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_nested_body(&mut self, body: hir::BodyId) {
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs b/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
index e2b9fe0f9f7..88d4acbdd8d 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
@@ -298,8 +298,8 @@ impl TaitConstraintLocator<'_> {
 impl<'tcx> intravisit::Visitor<'tcx> for TaitConstraintLocator<'tcx> {
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
     fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
         if let hir::ExprKind::Closure(closure) = ex.kind {
@@ -441,8 +441,8 @@ impl RpitConstraintChecker<'_> {
 impl<'tcx> intravisit::Visitor<'tcx> for RpitConstraintChecker<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
     fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
         if let hir::ExprKind::Closure(closure) = ex.kind {
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 57df3127a02..34124a6aa11 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -24,8 +24,8 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::{FileName, Ident, Span, Symbol, kw};
 use {rustc_ast as ast, rustc_hir as hir};
 
-pub fn id_to_string(map: &dyn rustc_hir::intravisit::Map<'_>, hir_id: HirId) -> String {
-    to_string(&map, |s| s.print_node(map.hir_node(hir_id)))
+pub fn id_to_string(cx: &dyn rustc_hir::intravisit::HirTyCtxt<'_>, hir_id: HirId) -> String {
+    to_string(&cx, |s| s.print_node(cx.hir_node(hir_id)))
 }
 
 pub enum AnnNode<'a> {
@@ -54,15 +54,15 @@ pub trait PpAnn {
     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
 }
 
-impl PpAnn for &dyn rustc_hir::intravisit::Map<'_> {
+impl PpAnn for &dyn rustc_hir::intravisit::HirTyCtxt<'_> {
     fn nested(&self, state: &mut State<'_>, nested: Nested) {
         match nested {
-            Nested::Item(id) => state.print_item(self.item(id)),
-            Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
-            Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
-            Nested::ForeignItem(id) => state.print_foreign_item(self.foreign_item(id)),
-            Nested::Body(id) => state.print_expr(self.body(id).value),
-            Nested::BodyParamPat(id, i) => state.print_pat(self.body(id).params[i].pat),
+            Nested::Item(id) => state.print_item(self.hir_item(id)),
+            Nested::TraitItem(id) => state.print_trait_item(self.hir_trait_item(id)),
+            Nested::ImplItem(id) => state.print_impl_item(self.hir_impl_item(id)),
+            Nested::ForeignItem(id) => state.print_foreign_item(self.hir_foreign_item(id)),
+            Nested::Body(id) => state.print_expr(self.hir_body(id).value),
+            Nested::BodyParamPat(id, i) => state.print_pat(self.hir_body(id).params[i].pat),
         }
     }
 }
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index 7963688203a..c0af5ea7bbf 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -2725,8 +2725,8 @@ struct FindClosureArg<'tcx> {
 impl<'tcx> Visitor<'tcx> for FindClosureArg<'tcx> {
     type NestedFilter = rustc_middle::hir::nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) {
diff --git a/compiler/rustc_incremental/src/assert_dep_graph.rs b/compiler/rustc_incremental/src/assert_dep_graph.rs
index 569034954c3..c2f9ebc5262 100644
--- a/compiler/rustc_incremental/src/assert_dep_graph.rs
+++ b/compiler/rustc_incremental/src/assert_dep_graph.rs
@@ -174,8 +174,8 @@ impl<'tcx> IfThisChanged<'tcx> {
 impl<'tcx> Visitor<'tcx> for IfThisChanged<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
diff --git a/compiler/rustc_incremental/src/persist/dirty_clean.rs b/compiler/rustc_incremental/src/persist/dirty_clean.rs
index 30590bf5d3c..a95599e7a86 100644
--- a/compiler/rustc_incremental/src/persist/dirty_clean.rs
+++ b/compiler/rustc_incremental/src/persist/dirty_clean.rs
@@ -455,8 +455,8 @@ impl<'tcx> FindAllAttrs<'tcx> {
 impl<'tcx> intravisit::Visitor<'tcx> for FindAllAttrs<'tcx> {
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_attribute(&mut self, attr: &'tcx Attribute) {
diff --git a/compiler/rustc_lint/src/late.rs b/compiler/rustc_lint/src/late.rs
index c0d3df17d77..f17570e4a81 100644
--- a/compiler/rustc_lint/src/late.rs
+++ b/compiler/rustc_lint/src/late.rs
@@ -84,8 +84,8 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
     /// Because lints are scoped lexically, we want to walk nested
     /// items in the context of the outer item, so enable
     /// deep-walking.
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.context.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.context.tcx
     }
 
     fn visit_nested_body(&mut self, body_id: hir::BodyId) {
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index 5a4ed68440a..7e13205bbf1 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -270,8 +270,8 @@ impl<'tcx> LintLevelsBuilder<'_, LintLevelQueryMap<'tcx>> {
 impl<'tcx> Visitor<'tcx> for LintLevelsBuilder<'_, LintLevelQueryMap<'tcx>> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.provider.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.provider.tcx
     }
 
     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
@@ -365,8 +365,8 @@ impl<'tcx> LintLevelMaximum<'tcx> {
 impl<'tcx> Visitor<'tcx> for LintLevelMaximum<'tcx> {
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     /// FIXME(blyxyas): In a future revision, we should also graph #![allow]s,
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 3ca4b3e235f..1ac2f6e81e5 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -2410,7 +2410,6 @@ pub(crate) fn provide(providers: &mut Providers) {
 /// use a different method for pretty-printing. Ideally this function
 /// should only ever be used as a fallback.
 pub fn rendered_const<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body<'_>, def_id: LocalDefId) -> String {
-    let hir = tcx.hir();
     let value = body.value;
 
     #[derive(PartialEq, Eq)]
@@ -2467,7 +2466,7 @@ pub fn rendered_const<'tcx>(tcx: TyCtxt<'tcx>, body: &hir::Body<'_>, def_id: Loc
 
         // Otherwise we prefer pretty-printing to get rid of extraneous whitespace, comments and
         // other formatting artifacts.
-        Literal | Simple => id_to_string(&hir, body.id().hir_id),
+        Literal | Simple => id_to_string(&tcx, body.id().hir_id),
 
         // FIXME: Omit the curly braces if the enclosing expression is an array literal
         //        with a repeated element (an `ExprKind::Repeat`) as in such case it
diff --git a/compiler/rustc_middle/src/hir/map.rs b/compiler/rustc_middle/src/hir/map.rs
index 737b491ef57..9bd35fdd6f0 100644
--- a/compiler/rustc_middle/src/hir/map.rs
+++ b/compiler/rustc_middle/src/hir/map.rs
@@ -1034,35 +1034,35 @@ impl<'hir> Map<'hir> {
     }
 }
 
-impl<'hir> intravisit::Map<'hir> for Map<'hir> {
-    fn hir_node(&self, hir_id: HirId) -> Node<'hir> {
-        self.tcx.hir_node(hir_id)
+impl<'tcx> intravisit::HirTyCtxt<'tcx> for TyCtxt<'tcx> {
+    fn hir_node(&self, hir_id: HirId) -> Node<'tcx> {
+        (*self).hir_node(hir_id)
     }
 
-    fn body(&self, id: BodyId) -> &'hir Body<'hir> {
-        self.tcx.hir_body(id)
+    fn hir_body(&self, id: BodyId) -> &'tcx Body<'tcx> {
+        (*self).hir_body(id)
     }
 
-    fn item(&self, id: ItemId) -> &'hir Item<'hir> {
-        self.tcx.hir_item(id)
+    fn hir_item(&self, id: ItemId) -> &'tcx Item<'tcx> {
+        (*self).hir_item(id)
     }
 
-    fn trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir> {
-        self.tcx.hir_trait_item(id)
+    fn hir_trait_item(&self, id: TraitItemId) -> &'tcx TraitItem<'tcx> {
+        (*self).hir_trait_item(id)
     }
 
-    fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir> {
-        self.tcx.hir_impl_item(id)
+    fn hir_impl_item(&self, id: ImplItemId) -> &'tcx ImplItem<'tcx> {
+        (*self).hir_impl_item(id)
     }
 
-    fn foreign_item(&self, id: ForeignItemId) -> &'hir ForeignItem<'hir> {
-        self.tcx.hir_foreign_item(id)
+    fn hir_foreign_item(&self, id: ForeignItemId) -> &'tcx ForeignItem<'tcx> {
+        (*self).hir_foreign_item(id)
     }
 }
 
 impl<'tcx> pprust_hir::PpAnn for TyCtxt<'tcx> {
     fn nested(&self, state: &mut pprust_hir::State<'_>, nested: pprust_hir::Nested) {
-        pprust_hir::PpAnn::nested(&(&self.hir() as &dyn intravisit::Map<'_>), state, nested)
+        pprust_hir::PpAnn::nested(&(self as &dyn intravisit::HirTyCtxt<'_>), state, nested)
     }
 }
 
@@ -1349,8 +1349,8 @@ impl<'tcx> ItemCollector<'tcx> {
 impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, item: &'hir Item<'hir>) {
diff --git a/compiler/rustc_middle/src/hir/nested_filter.rs b/compiler/rustc_middle/src/hir/nested_filter.rs
index adbe81bb22c..e18c28a8eac 100644
--- a/compiler/rustc_middle/src/hir/nested_filter.rs
+++ b/compiler/rustc_middle/src/hir/nested_filter.rs
@@ -1,5 +1,7 @@
 use rustc_hir::intravisit::nested_filter::NestedFilter;
 
+use crate::ty::TyCtxt;
+
 /// Do not visit nested item-like things, but visit nested things
 /// that are inside of an item-like.
 ///
@@ -12,8 +14,8 @@ use rustc_hir::intravisit::nested_filter::NestedFilter;
 /// and to have the visitor that visits the contents of each item
 /// using this setting.
 pub struct OnlyBodies(());
-impl<'hir> NestedFilter<'hir> for OnlyBodies {
-    type Map = crate::hir::map::Map<'hir>;
+impl<'tcx> NestedFilter<'tcx> for OnlyBodies {
+    type MaybeTyCtxt = TyCtxt<'tcx>;
     const INTER: bool = false;
     const INTRA: bool = true;
 }
@@ -24,8 +26,8 @@ impl<'hir> NestedFilter<'hir> for OnlyBodies {
 /// process everything within their lexical context. Typically you
 /// kick off the visit by doing `walk_krate()`.
 pub struct All(());
-impl<'hir> NestedFilter<'hir> for All {
-    type Map = crate::hir::map::Map<'hir>;
+impl<'tcx> NestedFilter<'tcx> for All {
+    type MaybeTyCtxt = TyCtxt<'tcx>;
     const INTER: bool = true;
     const INTRA: bool = true;
 }
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 081e7b1a43c..264995efe8f 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -10,7 +10,6 @@ mod unexpand;
 
 use rustc_hir as hir;
 use rustc_hir::intravisit::{Visitor, walk_expr};
-use rustc_middle::hir::map::Map;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::mir::coverage::{
     CoverageKind, DecisionInfo, FunctionCoverageInfo, Mapping, MappingKind,
@@ -348,7 +347,7 @@ fn extract_hole_spans_from_hir<'tcx>(
     hir_body: &hir::Body<'tcx>,
 ) -> Vec<Span> {
     struct HolesVisitor<'hir, F> {
-        hir: Map<'hir>,
+        tcx: TyCtxt<'hir>,
         visit_hole_span: F,
     }
 
@@ -360,8 +359,8 @@ fn extract_hole_spans_from_hir<'tcx>(
         ///   items contained within them.
         type NestedFilter = nested_filter::All;
 
-        fn nested_visit_map(&mut self) -> Self::Map {
-            self.hir
+        fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+            self.tcx
         }
 
         fn visit_item(&mut self, item: &'hir hir::Item<'hir>) {
@@ -388,7 +387,7 @@ fn extract_hole_spans_from_hir<'tcx>(
 
     let mut hole_spans = vec![];
     let mut visitor = HolesVisitor {
-        hir: tcx.hir(),
+        tcx,
         visit_hole_span: |hole_span| {
             // Discard any holes that aren't directly visible within the body span.
             if body_span.contains(hole_span) && body_span.eq_ctxt(hole_span) {
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index e96db885131..396a0cbc889 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -2606,8 +2606,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
diff --git a/compiler/rustc_passes/src/hir_id_validator.rs b/compiler/rustc_passes/src/hir_id_validator.rs
index 34d60d90be5..43f2f892e77 100644
--- a/compiler/rustc_passes/src/hir_id_validator.rs
+++ b/compiler/rustc_passes/src/hir_id_validator.rs
@@ -105,8 +105,8 @@ impl<'a, 'hir> HirIdValidator<'a, 'hir> {
 impl<'a, 'hir> intravisit::Visitor<'hir> for HirIdValidator<'a, 'hir> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_nested_item(&mut self, id: hir::ItemId) {
diff --git a/compiler/rustc_passes/src/lib_features.rs b/compiler/rustc_passes/src/lib_features.rs
index 600c46eb3d0..09d59e1f717 100644
--- a/compiler/rustc_passes/src/lib_features.rs
+++ b/compiler/rustc_passes/src/lib_features.rs
@@ -129,8 +129,8 @@ impl<'tcx> LibFeatureCollector<'tcx> {
 impl<'tcx> Visitor<'tcx> for LibFeatureCollector<'tcx> {
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_attribute(&mut self, attr: &'tcx Attribute) {
diff --git a/compiler/rustc_passes/src/loops.rs b/compiler/rustc_passes/src/loops.rs
index 6eef0b926a1..0fd980af0b5 100644
--- a/compiler/rustc_passes/src/loops.rs
+++ b/compiler/rustc_passes/src/loops.rs
@@ -87,8 +87,8 @@ pub(crate) fn provide(providers: &mut Providers) {
 impl<'hir> Visitor<'hir> for CheckLoopVisitor<'hir> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_anon_const(&mut self, c: &'hir hir::AnonConst) {
diff --git a/compiler/rustc_passes/src/naked_functions.rs b/compiler/rustc_passes/src/naked_functions.rs
index 23322be8f55..cb17b0f6cf5 100644
--- a/compiler/rustc_passes/src/naked_functions.rs
+++ b/compiler/rustc_passes/src/naked_functions.rs
@@ -259,8 +259,8 @@ struct CheckNakedAsmInNakedFn<'tcx> {
 impl<'tcx> Visitor<'tcx> for CheckNakedAsmInNakedFn<'tcx> {
     type NestedFilter = OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index fd30d0d4867..d045e61d1d4 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -394,8 +394,8 @@ impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
     /// deep-walking.
     type NestedFilter = nested_filter::All;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
@@ -616,8 +616,8 @@ impl<'tcx> MissingStabilityAnnotations<'tcx> {
 impl<'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
@@ -756,8 +756,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
     /// Because stability levels are scoped lexically, we want to walk
     /// nested items in the context of the outer item, so enable
     /// deep-walking.
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
index 57b614833af..55eb3f777d6 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
@@ -1202,8 +1202,8 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
 impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tecx.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tecx.tcx
     }
 
     fn visit_local(&mut self, local: &'tcx LetStmt<'tcx>) {
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/find_anon_type.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/find_anon_type.rs
index b9f3abc2534..5a303c3cd03 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/find_anon_type.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/find_anon_type.rs
@@ -3,7 +3,6 @@ use core::ops::ControlFlow;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{self, Visitor, VisitorExt};
 use rustc_hir::{self as hir, AmbigArg};
-use rustc_middle::hir::map::Map;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::resolve_bound_vars as rbv;
 use rustc_middle::ty::{self, Region, TyCtxt};
@@ -70,8 +69,8 @@ impl<'tcx> Visitor<'tcx> for FindNestedTypeVisitor<'tcx> {
     type Result = ControlFlow<&'tcx hir::Ty<'tcx>>;
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_ty(&mut self, arg: &'tcx hir::Ty<'tcx, AmbigArg>) -> Self::Result {
@@ -176,8 +175,8 @@ impl<'tcx> Visitor<'tcx> for TyPathVisitor<'tcx> {
     type Result = ControlFlow<()>;
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Map<'tcx> {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_lifetime(&mut self, lifetime: &hir::Lifetime) -> Self::Result {
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
index bbcd28c0835..0695cc57978 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
@@ -133,8 +133,8 @@ struct TypeParamSpanVisitor<'tcx> {
 impl<'tcx> Visitor<'tcx> for TypeParamSpanVisitor<'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_ty(&mut self, arg: &'tcx hir::Ty<'tcx, AmbigArg>) {
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
index d786d04b8f6..22d219cd64d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
@@ -68,8 +68,8 @@ impl<'hir> FindExprBySpan<'hir> {
 impl<'v> Visitor<'v> for FindExprBySpan<'v> {
     type NestedFilter = rustc_middle::hir::nested_filter::OnlyBodies;
 
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
+    fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt {
+        self.tcx
     }
 
     fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {