Auto merge of #112075 - WaffleLapkin:unmkII, r=lcnr

Replace `tcx.mk_re_*` with `Region::new_*`

Second step in implementing https://github.com/rust-lang/compiler-team/issues/616
r? `@lcnr`

42 files changed, 292 insertions, 234 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index f41795d60a0..cfcf31fce32 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -180,24 +180,25 @@ trait TypeOpInfo<'tcx> {
             return;
         };
 
-        let placeholder_region = tcx.mk_re_placeholder(ty::Placeholder {
-            universe: adjusted_universe.into(),
-            bound: placeholder.bound,
-        });
-
-        let error_region =
-            if let RegionElement::PlaceholderRegion(error_placeholder) = error_element {
-                let adjusted_universe =
-                    error_placeholder.universe.as_u32().checked_sub(base_universe.as_u32());
-                adjusted_universe.map(|adjusted| {
-                    tcx.mk_re_placeholder(ty::Placeholder {
-                        universe: adjusted.into(),
-                        bound: error_placeholder.bound,
-                    })
-                })
-            } else {
-                None
-            };
+        let placeholder_region = ty::Region::new_placeholder(
+            tcx,
+            ty::Placeholder { universe: adjusted_universe.into(), bound: placeholder.bound },
+        );
+
+        let error_region = if let RegionElement::PlaceholderRegion(error_placeholder) =
+            error_element
+        {
+            let adjusted_universe =
+                error_placeholder.universe.as_u32().checked_sub(base_universe.as_u32());
+            adjusted_universe.map(|adjusted| {
+                ty::Region::new_placeholder(
+                    tcx,
+                    ty::Placeholder { universe: adjusted.into(), bound: error_placeholder.bound },
+                )
+            })
+        } else {
+            None
+        };
 
         debug!(?placeholder_region);
 
@@ -390,7 +391,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
         error_region,
         &region_constraints,
         |vid| ocx.infcx.region_var_origin(vid),
-        |vid| ocx.infcx.universe_of_region(ocx.infcx.tcx.mk_re_var(vid)),
+        |vid| ocx.infcx.universe_of_region(ty::Region::new_var(ocx.infcx.tcx, vid)),
     )
 }
 
@@ -411,7 +412,7 @@ fn try_extract_error_from_region_constraints<'tcx>(
                 }
                 // FIXME: Should this check the universe of the var?
                 Constraint::VarSubReg(vid, sup) if sup == placeholder_region => {
-                    Some((infcx.tcx.mk_re_var(vid), cause.clone()))
+                    Some((ty::Region::new_var(infcx.tcx, vid), cause.clone()))
                 }
                 _ => None,
             }
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 889acb3acbe..b5014a3f479 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -441,7 +441,7 @@ fn for_each_region_constraint<'tcx>(
         let subject = match req.subject {
             ClosureOutlivesSubject::Region(subject) => format!("{:?}", subject),
             ClosureOutlivesSubject::Ty(ty) => {
-                format!("{:?}", ty.instantiate(tcx, |vid| tcx.mk_re_var(vid)))
+                format!("{:?}", ty.instantiate(tcx, |vid| ty::Region::new_var(tcx, vid)))
             }
         };
         with_msg(format!("where {}: {:?}", subject, req.outlived_free_region,))?;
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 50b246b1478..2a0cb49672b 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -1158,7 +1158,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 .universal_regions_outlived_by(r_scc)
                 .filter(|&u_r| !self.universal_regions.is_local_free_region(u_r))
                 .find(|&u_r| self.eval_equal(u_r, r_vid))
-                .map(|u_r| tcx.mk_re_var(u_r))
+                .map(|u_r| ty::Region::new_var(tcx, u_r))
                 // In the case of a failure, use `ReErased`. We will eventually
                 // return `None` in this case.
                 .unwrap_or(tcx.lifetimes.re_erased)
@@ -1355,7 +1355,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             let vid = self.to_region_vid(r);
             let scc = self.constraint_sccs.scc(vid);
             let repr = self.scc_representatives[scc];
-            tcx.mk_re_var(repr)
+            ty::Region::new_var(tcx, repr)
         })
     }
 
@@ -1779,7 +1779,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             }
 
             // If not, report an error.
-            let member_region = infcx.tcx.mk_re_var(member_region_vid);
+            let member_region = ty::Region::new_var(infcx.tcx, member_region_vid);
             errors_buffer.push(RegionErrorKind::UnexpectedHiddenRegion {
                 span: m_c.definition_span,
                 hidden_ty: m_c.hidden_ty,
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index 7fc89e89a35..33f07c1d8fc 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -92,7 +92,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     }
                     None => {
                         subst_regions.push(vid);
-                        infcx.tcx.mk_re_error_with_message(
+                        ty::Region::new_error_with_message(
+                            infcx.tcx,
                             concrete_type.span,
                             "opaque type with non-universal region substs",
                         )
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 51a84ce6cad..03f933681bc 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -139,7 +139,7 @@ pub(crate) fn type_check<'mir, 'tcx>(
     upvars: &[Upvar<'tcx>],
     use_polonius: bool,
 ) -> MirTypeckResults<'tcx> {
-    let implicit_region_bound = infcx.tcx.mk_re_var(universal_regions.fr_fn_body);
+    let implicit_region_bound = ty::Region::new_var(infcx.tcx, universal_regions.fr_fn_body);
     let mut constraints = MirTypeckRegionConstraints {
         placeholder_indices: PlaceholderIndices::default(),
         placeholder_index_to_region: IndexVec::default(),
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 56f078f2da8..c871703429a 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -500,7 +500,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     .next_nll_region_var(FR, || RegionCtxt::Free(Symbol::intern("c-variadic")))
                     .as_var();
 
-                let region = self.infcx.tcx.mk_re_var(reg_vid);
+                let region = ty::Region::new_var(self.infcx.tcx, reg_vid);
                 let va_list_ty =
                     self.infcx.tcx.type_of(va_list_did).subst(self.infcx.tcx, &[region.into()]);
 
@@ -660,7 +660,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = tcx.mk_re_late_bound(ty::INNERMOST, br);
+                let env_region = ty::Region::new_late_bound(tcx, ty::INNERMOST, br);
                 let closure_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
 
                 // The "inputs" of the closure in the
@@ -778,7 +778,8 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
     {
         let (value, _map) = self.tcx.replace_late_bound_regions(value, |br| {
             debug!(?br);
-            let liberated_region = self.tcx.mk_re_free(all_outlive_scope.to_def_id(), br.kind);
+            let liberated_region =
+                ty::Region::new_free(self.tcx, all_outlive_scope.to_def_id(), br.kind);
             let region_vid = {
                 let name = match br.kind.get_name() {
                     Some(name) => name,
@@ -889,7 +890,7 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
     where
         T: TypeFoldable<TyCtxt<'tcx>>,
     {
-        tcx.fold_regions(value, |region, _| tcx.mk_re_var(self.to_region_vid(region)))
+        tcx.fold_regions(value, |region, _| ty::Region::new_var(tcx, self.to_region_vid(region)))
     }
 }
 
@@ -929,7 +930,7 @@ fn for_each_late_bound_region_in_item<'tcx>(
 
     for bound_var in tcx.late_bound_vars(tcx.hir().local_def_id_to_hir_id(mir_def_id)) {
         let ty::BoundVariableKind::Region(bound_region) = bound_var else { continue; };
-        let liberated_region = tcx.mk_re_free(mir_def_id.to_def_id(), bound_region);
+        let liberated_region = ty::Region::new_free(tcx, mir_def_id.to_def_id(), bound_region);
         f(liberated_region);
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 284ae0e1e58..d9796e8ffe0 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -239,7 +239,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     var: ty::BoundVar::from_u32(index),
                     kind: ty::BrNamed(def_id, name),
                 };
-                tcx.mk_re_late_bound(debruijn, br)
+                ty::Region::new_late_bound(tcx, debruijn, br)
             }
 
             Some(rbv::ResolvedArg::EarlyBound(def_id)) => {
@@ -247,12 +247,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local());
                 let generics = tcx.generics_of(item_def_id);
                 let index = generics.param_def_id_to_index[&def_id];
-                tcx.mk_re_early_bound(ty::EarlyBoundRegion { def_id, index, name })
+                ty::Region::new_early_bound(tcx, ty::EarlyBoundRegion { def_id, index, name })
             }
 
             Some(rbv::ResolvedArg::Free(scope, id)) => {
                 let name = lifetime_name(id.expect_local());
-                tcx.mk_re_free(scope, ty::BrNamed(id, name))
+                ty::Region::new_free(tcx, scope, ty::BrNamed(id, name))
 
                 // (*) -- not late-bound, won't change
             }
@@ -269,7 +269,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     // elision. `resolve_lifetime` should have
                     // reported an error in this case -- but if
                     // not, let's error out.
-                    tcx.mk_re_error_with_message(
+                    ty::Region::new_error_with_message(
+                        tcx,
                         lifetime.ident.span,
                         "unelided lifetime in signature",
                     )
@@ -485,7 +486,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             debug!(?param, "unelided lifetime in signature");
 
                             // This indicates an illegal lifetime in a non-assoc-trait position
-                            tcx.mk_re_error_with_message(
+                            ty::Region::new_error_with_message(
+                                tcx,
                                 self.span,
                                 "unelided lifetime in signature",
                             )
@@ -1219,15 +1221,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             let substs =
                 candidate.skip_binder().substs.extend_to(tcx, assoc_item.def_id, |param, _| {
                     let subst = match param.kind {
-                        GenericParamDefKind::Lifetime => tcx
-                            .mk_re_late_bound(
-                                ty::INNERMOST,
-                                ty::BoundRegion {
-                                    var: ty::BoundVar::from_usize(num_bound_vars),
-                                    kind: ty::BoundRegionKind::BrNamed(param.def_id, param.name),
-                                },
-                            )
-                            .into(),
+                        GenericParamDefKind::Lifetime => ty::Region::new_late_bound(
+                            tcx,
+                            ty::INNERMOST,
+                            ty::BoundRegion {
+                                var: ty::BoundVar::from_usize(num_bound_vars),
+                                kind: ty::BoundRegionKind::BrNamed(param.def_id, param.name),
+                            },
+                        )
+                        .into(),
                         GenericParamDefKind::Type { .. } => tcx
                             .mk_bound(
                                 ty::INNERMOST,
@@ -1804,7 +1806,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         } else {
                             err.emit()
                         };
-                        tcx.mk_re_error(e)
+                        ty::Region::new_error(tcx, e)
                     })
                 }
             })
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 18b6537a8e9..be901b7236f 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -472,7 +472,8 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         if let ty::ReFree(fr) = *r {
-            self.tcx.mk_re_free(
+            ty::Region::new_free(
+                self.tcx,
                 fr.scope,
                 self.mapping.get(&fr.bound_region).copied().unwrap_or(fr.bound_region),
             )
@@ -786,9 +787,9 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
                     }
                     let Some(ty::ReEarlyBound(e)) = map.get(&region.into()).map(|r| r.expect_region().kind())
                     else {
-                        return tcx.mk_re_error_with_message(return_span, "expected ReFree to map to ReEarlyBound")
+                        return ty::Region::new_error_with_message(tcx, return_span, "expected ReFree to map to ReEarlyBound")
                     };
-                    tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    ty::Region::new_early_bound(tcx, ty::EarlyBoundRegion {
                         def_id: e.def_id,
                         name: e.name,
                         index: (e.index as usize - num_trait_substs + num_impl_substs) as u32,
@@ -1933,7 +1934,8 @@ pub(super) fn check_type_bounds<'tcx>(
                 let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
                 let bound_var = ty::BoundVariableKind::Region(kind);
                 bound_vars.push(bound_var);
-                tcx.mk_re_late_bound(
+                ty::Region::new_late_bound(
+                    tcx,
                     ty::INNERMOST,
                     ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind },
                 )
diff --git a/compiler/rustc_hir_analysis/src/check/dropck.rs b/compiler/rustc_hir_analysis/src/check/dropck.rs
index eeb69c389cd..897e4135fa0 100644
--- a/compiler/rustc_hir_analysis/src/check/dropck.rs
+++ b/compiler/rustc_hir_analysis/src/check/dropck.rs
@@ -183,7 +183,7 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
                 }
                 RegionResolutionError::SubSupConflict(_, _, _, a, _, b, _) => format!("{b}: {a}"),
                 RegionResolutionError::UpperBoundUniverseConflict(a, _, _, _, b) => {
-                    format!("{b}: {a}", a = tcx.mk_re_var(a))
+                    format!("{b}: {a}", a = ty::Region::new_var(tcx, a))
                 }
             };
             guar = Some(
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index fbd4a577d68..1f18017f00b 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -145,11 +145,13 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
     ]);
     let mk_va_list_ty = |mutbl| {
         tcx.lang_items().va_list().map(|did| {
-            let region = tcx.mk_re_late_bound(
+            let region = ty::Region::new_late_bound(
+                tcx,
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(None) },
             );
-            let env_region = tcx.mk_re_late_bound(
+            let env_region = ty::Region::new_late_bound(
+                tcx,
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrEnv },
             );
@@ -393,7 +395,12 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                 let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(None) };
                 (
                     1,
-                    vec![tcx.mk_imm_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), param(0))],
+                    vec![
+                        tcx.mk_imm_ref(
+                            ty::Region::new_late_bound(tcx, ty::INNERMOST, br),
+                            param(0),
+                        ),
+                    ],
                     tcx.mk_projection(discriminant_def_id, tcx.mk_substs(&[param(0).into()])),
                 )
             }
@@ -443,7 +450,8 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
             sym::raw_eq => {
                 let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(None) };
-                let param_ty = tcx.mk_imm_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), param(0));
+                let param_ty =
+                    tcx.mk_imm_ref(ty::Region::new_late_bound(tcx, ty::INNERMOST, br), param(0));
                 (1, vec![param_ty; 2], tcx.types.bool)
             }
 
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 4c513c4d8cc..7295d1dc0fd 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -556,11 +556,14 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
                 // Same for the region. In our example, 'a corresponds
                 // to the 'me parameter.
                 let region_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
-                    def_id: region_param.def_id,
-                    index: region_param.index,
-                    name: region_param.name,
-                });
+                let region_param = ty::Region::new_early_bound(
+                    tcx,
+                    ty::EarlyBoundRegion {
+                        def_id: region_param.def_id,
+                        index: region_param.index,
+                        name: region_param.name,
+                    },
+                );
                 // The predicate we expect to see. (In our example,
                 // `Self: 'me`.)
                 let clause = ty::PredicateKind::Clause(ty::Clause::TypeOutlives(
@@ -593,18 +596,24 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
                 debug!("required clause: {region_a} must outlive {region_b}");
                 // Translate into the generic parameters of the GAT.
                 let region_a_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_a_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
-                    def_id: region_a_param.def_id,
-                    index: region_a_param.index,
-                    name: region_a_param.name,
-                });
+                let region_a_param = ty::Region::new_early_bound(
+                    tcx,
+                    ty::EarlyBoundRegion {
+                        def_id: region_a_param.def_id,
+                        index: region_a_param.index,
+                        name: region_a_param.name,
+                    },
+                );
                 // Same for the region.
                 let region_b_param = gat_generics.param_at(*region_b_idx, tcx);
-                let region_b_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
-                    def_id: region_b_param.def_id,
-                    index: region_b_param.index,
-                    name: region_b_param.name,
-                });
+                let region_b_param = ty::Region::new_early_bound(
+                    tcx,
+                    ty::EarlyBoundRegion {
+                        def_id: region_b_param.def_id,
+                        index: region_b_param.index,
+                        name: region_b_param.name,
+                    },
+                );
                 // The predicate we expect to see.
                 let clause = ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(region_a_param, region_b_param),
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 75d99fee152..e7a8fd8ffd7 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -440,7 +440,7 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
                                     self.tcx.replace_late_bound_regions_uncached(
                                         poly_trait_ref,
                                         |_| {
-                                            self.tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                                            ty::Region::new_early_bound(self.tcx, ty::EarlyBoundRegion {
                                                 def_id: item_def_id,
                                                 index: 0,
                                                 name: Symbol::intern(&lt_name),
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index e5b5dae551e..70d950eddd8 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -306,11 +306,14 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
 
             let Some(dup_index) = generics.param_def_id_to_index(tcx, dup_def) else { bug!() };
 
-            let dup_region = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
-                def_id: dup_def,
-                index: dup_index,
-                name: duplicate.name.ident().name,
-            });
+            let dup_region = ty::Region::new_early_bound(
+                tcx,
+                ty::EarlyBoundRegion {
+                    def_id: dup_def,
+                    index: dup_index,
+                    name: duplicate.name.ident().name,
+                },
+            );
             predicates.push((
                 ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(orig_region, dup_region),
diff --git a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
index 427d6f8803c..fb28233bfb1 100644
--- a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
+++ b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
@@ -269,7 +269,7 @@ pub fn resolve_interior<'a, 'tcx>(
                     },
                     _ => mk_bound_region(ty::BrAnon(None)),
                 };
-                let r = fcx.tcx.mk_re_late_bound(current_depth, br);
+                let r = ty::Region::new_late_bound(fcx.tcx, current_depth, br);
                 r
             });
             captured_tys.insert(ty).then(|| {
@@ -295,7 +295,11 @@ pub fn resolve_interior<'a, 'tcx>(
                     let var = ty::BoundVar::from_usize(bound_vars.len());
                     bound_vars.push(ty::BoundVariableKind::Region(kind));
                     counter += 1;
-                    fcx.tcx.mk_re_late_bound(ty::INNERMOST, ty::BoundRegion { var, kind })
+                    ty::Region::new_late_bound(
+                        fcx.tcx,
+                        ty::INNERMOST,
+                        ty::BoundRegion { var, kind },
+                    )
                 },
                 types: &mut |b| bug!("unexpected bound ty in binder: {b:?}"),
                 consts: &mut |b, ty| bug!("unexpected bound ct in binder: {b:?} {ty}"),
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index 427d05c8b4d..bf53a73f398 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -771,7 +771,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     ) -> ty::Region<'tcx> {
         let var = self.canonical_var(info, r.into());
         let br = ty::BoundRegion { var, kind: ty::BrAnon(None) };
-        self.interner().mk_re_late_bound(self.binder_index, br)
+        ty::Region::new_late_bound(self.interner(), self.binder_index, br)
     }
 
     /// Given a type variable `ty_var` of the given kind, first check
diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index 2abdd5b0aec..c8c318c3f02 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -141,7 +141,7 @@ impl<'tcx> InferCtxt<'tcx> {
             CanonicalVarKind::PlaceholderRegion(ty::PlaceholderRegion { universe, bound }) => {
                 let universe_mapped = universe_map(universe);
                 let placeholder_mapped = ty::PlaceholderRegion { universe: universe_mapped, bound };
-                self.tcx.mk_re_placeholder(placeholder_mapped).into()
+                ty::Region::new_placeholder(self.tcx, placeholder_mapped).into()
             }
 
             CanonicalVarKind::Const(ui, ty) => self
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index 88256c819f4..2cf8d8c702d 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -668,14 +668,15 @@ pub fn make_query_region_constraints<'tcx>(
             let constraint = match *k {
                 // Swap regions because we are going from sub (<=) to outlives
                 // (>=).
-                Constraint::VarSubVar(v1, v2) => {
-                    ty::OutlivesPredicate(tcx.mk_re_var(v2).into(), tcx.mk_re_var(v1))
-                }
+                Constraint::VarSubVar(v1, v2) => ty::OutlivesPredicate(
+                    ty::Region::new_var(tcx, v2).into(),
+                    ty::Region::new_var(tcx, v1),
+                ),
                 Constraint::VarSubReg(v1, r2) => {
-                    ty::OutlivesPredicate(r2.into(), tcx.mk_re_var(v1))
+                    ty::OutlivesPredicate(r2.into(), ty::Region::new_var(tcx, v1))
                 }
                 Constraint::RegSubVar(r1, v2) => {
-                    ty::OutlivesPredicate(tcx.mk_re_var(v2).into(), r1)
+                    ty::OutlivesPredicate(ty::Region::new_var(tcx, v2).into(), r1)
                 }
                 Constraint::RegSubReg(r1, r2) => ty::OutlivesPredicate(r2.into(), r1),
             };
@@ -719,7 +720,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
     }
 
     fn next_placeholder_region(&mut self, placeholder: ty::PlaceholderRegion) -> ty::Region<'tcx> {
-        self.infcx.tcx.mk_re_placeholder(placeholder)
+        ty::Region::new_placeholder(self.infcx.tcx, placeholder)
     }
 
     fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
index c9c1f0aeaac..0b3bc1ce6b3 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
@@ -79,7 +79,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_re_var(*vid)),
+                Some(ty::Region::new_var(self.tcx(), *vid)),
                 cause,
                 Some(*sub_placeholder),
                 Some(*sup_placeholder),
@@ -95,7 +95,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 _,
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_re_var(*vid)),
+                Some(ty::Region::new_var(self.tcx(), *vid)),
                 cause,
                 Some(*sub_placeholder),
                 None,
@@ -111,7 +111,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_re_var(*vid)),
+                Some(ty::Region::new_var(self.tcx(), *vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
@@ -127,7 +127,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_re_var(*vid)),
+                Some(ty::Region::new_var(self.tcx(), *vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
@@ -141,7 +141,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 SubregionOrigin::Subtype(box TypeTrace { cause, values }),
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_re_var(*vid)),
+                Some(ty::Region::new_var(self.tcx(), *vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
index c304cd25c9c..1c298e7d4ec 100644
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
@@ -82,8 +82,10 @@ impl<'tcx> InferCtxt<'tcx> {
 
         let delegate = FnMutDelegate {
             regions: &mut |br: ty::BoundRegion| {
-                self.tcx
-                    .mk_re_placeholder(ty::PlaceholderRegion { universe: next_universe, bound: br })
+                ty::Region::new_placeholder(
+                    self.tcx,
+                    ty::PlaceholderRegion { universe: next_universe, bound: br },
+                )
             },
             types: &mut |bound_ty: ty::BoundTy| {
                 self.tcx.mk_placeholder(ty::PlaceholderType {
diff --git a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
index 8482ae2aa38..485e34fe2bf 100644
--- a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
+++ b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
@@ -347,7 +347,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                     // name the placeholder, then the placeholder is
                     // larger; otherwise, the only ancestor is `'static`.
                     Err(placeholder) if empty_ui.can_name(placeholder.universe) => {
-                        self.tcx().mk_re_placeholder(placeholder)
+                        ty::Region::new_placeholder(self.tcx(), placeholder)
                     }
                     Err(_) => self.tcx().lifetimes.re_static,
                 };
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index cd99fc31212..b49282726fd 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -1065,7 +1065,7 @@ impl<'tcx> InferCtxt<'tcx> {
     ) -> ty::Region<'tcx> {
         let region_var =
             self.inner.borrow_mut().unwrap_region_constraints().new_region_var(universe, origin);
-        self.tcx.mk_re_var(region_var)
+        ty::Region::new_var(self.tcx, region_var)
     }
 
     /// Return the universe that the region `r` was created in. For
diff --git a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
index 89cfc9ea3d1..5f4093c1c3c 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
@@ -280,7 +280,7 @@ impl<'me, 'tcx> LeakCheck<'me, 'tcx> {
         placeholder1: ty::PlaceholderRegion,
         placeholder2: ty::PlaceholderRegion,
     ) -> TypeError<'tcx> {
-        self.error(placeholder1, self.tcx.mk_re_placeholder(placeholder2))
+        self.error(placeholder1, ty::Region::new_placeholder(self.tcx, placeholder2))
     }
 
     fn error(
@@ -413,13 +413,13 @@ impl<'tcx> MiniGraph<'tcx> {
         for undo_entry in undo_log {
             match undo_entry {
                 &AddConstraint(Constraint::VarSubVar(a, b)) => {
-                    each_edge(tcx.mk_re_var(a), tcx.mk_re_var(b));
+                    each_edge(ty::Region::new_var(tcx, a), ty::Region::new_var(tcx, b));
                 }
                 &AddConstraint(Constraint::RegSubVar(a, b)) => {
-                    each_edge(a, tcx.mk_re_var(b));
+                    each_edge(a, ty::Region::new_var(tcx, b));
                 }
                 &AddConstraint(Constraint::VarSubReg(a, b)) => {
-                    each_edge(tcx.mk_re_var(a), b);
+                    each_edge(ty::Region::new_var(tcx, a), b);
                 }
                 &AddConstraint(Constraint::RegSubReg(a, b)) => {
                     each_edge(a, b);
diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
index c7a307b89e4..cd8d23bf635 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
@@ -610,13 +610,13 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         let resolved = ut
             .probe_value(root_vid)
             .get_value_ignoring_universes()
-            .unwrap_or_else(|| tcx.mk_re_var(root_vid));
+            .unwrap_or_else(|| ty::Region::new_var(tcx, root_vid));
 
         // Don't resolve a variable to a region that it cannot name.
         if self.var_universe(vid).can_name(self.universe(resolved)) {
             resolved
         } else {
-            tcx.mk_re_var(vid)
+            ty::Region::new_var(tcx, vid)
         }
     }
 
@@ -637,7 +637,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
     ) -> Region<'tcx> {
         let vars = TwoRegions { a, b };
         if let Some(&c) = self.combine_map(t).get(&vars) {
-            return tcx.mk_re_var(c);
+            return ty::Region::new_var(tcx, c);
         }
         let a_universe = self.universe(a);
         let b_universe = self.universe(b);
@@ -645,7 +645,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         let c = self.new_region_var(c_universe, MiscVariable(origin.span()));
         self.combine_map(t).insert(vars, c);
         self.undo_log.push(AddCombination(t, vars));
-        let new_r = tcx.mk_re_var(c);
+        let new_r = ty::Region::new_var(tcx, c);
         for old_r in [a, b] {
             match t {
                 Glb => self.make_subregion(origin.clone(), new_r, old_r),
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index 56171314944..29dae67bfca 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -415,7 +415,7 @@ impl<'tcx> CanonicalVarValues<'tcx> {
                                 var: ty::BoundVar::from_usize(i),
                                 kind: ty::BrAnon(None),
                             };
-                            tcx.mk_re_late_bound(ty::INNERMOST, br).into()
+                            ty::Region::new_late_bound(tcx, ty::INNERMOST, br).into()
                         }
                         CanonicalVarKind::Const(_, ty)
                         | CanonicalVarKind::PlaceholderConst(_, ty) => tcx
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index 53fd2dd23a7..a15c419da7a 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -413,7 +413,7 @@ impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
             ty::ReVar(vid) => {
                 let br =
                     ty::BoundRegion { var: ty::BoundVar::new(vid.index()), kind: ty::BrAnon(None) };
-                tcx.mk_re_late_bound(depth, br)
+                ty::Region::new_late_bound(tcx, depth, br)
             }
             _ => bug!("unexpected region in ClosureOutlivesSubjectTy: {r:?}"),
         });
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 7fc75674da5..76f52bc34ed 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -264,7 +264,7 @@ impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for mir::Place<'tcx> {
 
 impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Region<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        decoder.interner().mk_region_from_kind(Decodable::decode(decoder))
+        ty::Region::new_from_kind(decoder.interner(), Decodable::decode(decoder))
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 4fdd3f26316..77725f0b3b6 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -723,34 +723,6 @@ impl<'tcx> TyCtxt<'tcx> {
         self.mk_ty_from_kind(Error(reported))
     }
 
-    /// Constructs a `RegionKind::ReError` lifetime.
-    #[track_caller]
-    pub fn mk_re_error(self, reported: ErrorGuaranteed) -> Region<'tcx> {
-        self.intern_region(ty::ReError(reported))
-    }
-
-    /// Constructs a `RegionKind::ReError` lifetime and registers a `delay_span_bug` to ensure it
-    /// gets used.
-    #[track_caller]
-    pub fn mk_re_error_misc(self) -> Region<'tcx> {
-        self.mk_re_error_with_message(
-            DUMMY_SP,
-            "RegionKind::ReError constructed but no error reported",
-        )
-    }
-
-    /// Constructs a `RegionKind::ReError` lifetime and registers a `delay_span_bug` with the given
-    /// `msg` to ensure it gets used.
-    #[track_caller]
-    pub fn mk_re_error_with_message<S: Into<MultiSpan>>(
-        self,
-        span: S,
-        msg: &'static str,
-    ) -> Region<'tcx> {
-        let reported = self.sess.delay_span_bug(span, msg);
-        self.mk_re_error(reported)
-    }
-
     /// Like [TyCtxt::ty_error] but for constants, with current `ErrorGuaranteed`
     #[track_caller]
     pub fn const_error(self, ty: Ty<'tcx>, reported: ErrorGuaranteed) -> Const<'tcx> {
@@ -1529,9 +1501,9 @@ macro_rules! direct_interners {
 
 // Functions with a `mk_` prefix are intended for use outside this file and
 // crate. Functions with an `intern_` prefix are intended for use within this
-// file only, and have a corresponding `mk_` function.
+// crate only, and have a corresponding `mk_` function.
 direct_interners! {
-    region: intern_region(RegionKind<'tcx>): Region -> Region<'tcx>,
+    region: pub(crate) intern_region(RegionKind<'tcx>): Region -> Region<'tcx>,
     const_: intern_const(ConstData<'tcx>): Const -> Const<'tcx>,
     const_allocation: pub mk_const_alloc(Allocation): ConstAllocation -> ConstAllocation<'tcx>,
     layout: pub mk_layout(LayoutS): Layout -> Layout<'tcx>,
@@ -2006,7 +1978,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_param_from_def(self, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
         match param.kind {
             GenericParamDefKind::Lifetime => {
-                self.mk_re_early_bound(param.to_early_bound_region_data()).into()
+                ty::Region::new_early_bound(self, param.to_early_bound_region_data()).into()
             }
             GenericParamDefKind::Type { .. } => self.mk_ty_param(param.index, param.name).into(),
             GenericParamDefKind::Const { .. } => self
@@ -2046,65 +2018,6 @@ impl<'tcx> TyCtxt<'tcx> {
         self.mk_alias(ty::Opaque, self.mk_alias_ty(def_id, substs))
     }
 
-    #[inline]
-    pub fn mk_re_early_bound(self, early_bound_region: ty::EarlyBoundRegion) -> Region<'tcx> {
-        self.intern_region(ty::ReEarlyBound(early_bound_region))
-    }
-
-    #[inline]
-    pub fn mk_re_late_bound(
-        self,
-        debruijn: ty::DebruijnIndex,
-        bound_region: ty::BoundRegion,
-    ) -> Region<'tcx> {
-        // Use a pre-interned one when possible.
-        if let ty::BoundRegion { var, kind: ty::BrAnon(None) } = bound_region
-            && let Some(inner) = self.lifetimes.re_late_bounds.get(debruijn.as_usize())
-            && let Some(re) = inner.get(var.as_usize()).copied()
-        {
-            re
-        } else {
-            self.intern_region(ty::ReLateBound(debruijn, bound_region))
-        }
-    }
-
-    #[inline]
-    pub fn mk_re_free(self, scope: DefId, bound_region: ty::BoundRegionKind) -> Region<'tcx> {
-        self.intern_region(ty::ReFree(ty::FreeRegion { scope, bound_region }))
-    }
-
-    #[inline]
-    pub fn mk_re_var(self, v: ty::RegionVid) -> Region<'tcx> {
-        // Use a pre-interned one when possible.
-        self.lifetimes
-            .re_vars
-            .get(v.as_usize())
-            .copied()
-            .unwrap_or_else(|| self.intern_region(ty::ReVar(v)))
-    }
-
-    #[inline]
-    pub fn mk_re_placeholder(self, placeholder: ty::PlaceholderRegion) -> Region<'tcx> {
-        self.intern_region(ty::RePlaceholder(placeholder))
-    }
-
-    // Avoid this in favour of more specific `mk_re_*` methods, where possible,
-    // to avoid the cost of the `match`.
-    pub fn mk_region_from_kind(self, kind: ty::RegionKind<'tcx>) -> Region<'tcx> {
-        match kind {
-            ty::ReEarlyBound(region) => self.mk_re_early_bound(region),
-            ty::ReLateBound(debruijn, region) => self.mk_re_late_bound(debruijn, region),
-            ty::ReFree(ty::FreeRegion { scope, bound_region }) => {
-                self.mk_re_free(scope, bound_region)
-            }
-            ty::ReStatic => self.lifetimes.re_static,
-            ty::ReVar(vid) => self.mk_re_var(vid),
-            ty::RePlaceholder(region) => self.mk_re_placeholder(region),
-            ty::ReErased => self.lifetimes.re_erased,
-            ty::ReError(reported) => self.mk_re_error(reported),
-        }
-    }
-
     pub fn mk_place_field(self, place: Place<'tcx>, f: FieldIdx, ty: Ty<'tcx>) -> Place<'tcx> {
         self.mk_place_elem(place, PlaceElem::Field(f, ty))
     }
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index 25890eb15cd..149ce29b8d9 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -213,7 +213,7 @@ where
                     // debruijn index. Then we adjust it to the
                     // correct depth.
                     assert_eq!(debruijn1, ty::INNERMOST);
-                    self.tcx.mk_re_late_bound(debruijn, br)
+                    ty::Region::new_late_bound(self.tcx, debruijn, br)
                 } else {
                     region
                 }
@@ -328,7 +328,7 @@ impl<'tcx> TyCtxt<'tcx> {
         T: TypeFoldable<TyCtxt<'tcx>>,
     {
         self.replace_late_bound_regions_uncached(value, |br| {
-            self.mk_re_free(all_outlive_scope, br.kind)
+            ty::Region::new_free(self, all_outlive_scope, br.kind)
         })
     }
 
@@ -341,7 +341,8 @@ impl<'tcx> TyCtxt<'tcx> {
             value,
             FnMutDelegate {
                 regions: &mut |r: ty::BoundRegion| {
-                    self.mk_re_late_bound(
+                    ty::Region::new_late_bound(
+                        self,
                         ty::INNERMOST,
                         ty::BoundRegion { var: shift_bv(r.var), kind: r.kind },
                     )
@@ -383,7 +384,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     .or_insert_with(|| ty::BoundVariableKind::Region(ty::BrAnon(None)))
                     .expect_region();
                 let br = ty::BoundRegion { var, kind };
-                self.tcx.mk_re_late_bound(ty::INNERMOST, br)
+                ty::Region::new_late_bound(self.tcx, ty::INNERMOST, br)
             }
             fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
                 let entry = self.map.entry(bt.var);
@@ -451,7 +452,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Shifter<'tcx> {
         match *r {
             ty::ReLateBound(debruijn, br) if debruijn >= self.current_index => {
                 let debruijn = debruijn.shifted_in(self.amount);
-                self.tcx.mk_re_late_bound(debruijn, br)
+                ty::Region::new_late_bound(self.tcx, debruijn, br)
             }
             _ => r,
         }
@@ -492,7 +493,7 @@ pub fn shift_region<'tcx>(
 ) -> ty::Region<'tcx> {
     match *region {
         ty::ReLateBound(debruijn, br) if amount > 0 => {
-            tcx.mk_re_late_bound(debruijn.shifted_in(amount), br)
+            ty::Region::new_late_bound(tcx, debruijn.shifted_in(amount), br)
         }
         _ => region,
     }
diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index b27ee8cbad0..76a6a421282 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -100,7 +100,7 @@ impl GenericParamDef {
         preceding_substs: &[ty::GenericArg<'tcx>],
     ) -> ty::GenericArg<'tcx> {
         match &self.kind {
-            ty::GenericParamDefKind::Lifetime => tcx.mk_re_error_misc().into(),
+            ty::GenericParamDefKind::Lifetime => ty::Region::new_error_misc(tcx).into(),
             ty::GenericParamDefKind::Type { .. } => tcx.ty_error_misc().into(),
             ty::GenericParamDefKind::Const { .. } => {
                 tcx.const_error_misc(tcx.type_of(self.def_id).subst(tcx, preceding_substs)).into()
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs
index 1b336b7bfc6..d1ed7be3d2e 100644
--- a/compiler/rustc_middle/src/ty/opaque_types.rs
+++ b/compiler/rustc_middle/src/ty/opaque_types.rs
@@ -141,7 +141,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseMapper<'tcx> {
                     )
                     .emit();
 
-                self.interner().mk_re_error(e)
+                ty::Region::new_error(self.interner(), e)
             }
         }
     }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 94915923c31..6156fdf7eac 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -184,7 +184,7 @@ impl<'tcx> RegionHighlightMode<'tcx> {
 
     /// Convenience wrapper for `highlighting_region`.
     pub fn highlighting_region_vid(&mut self, vid: ty::RegionVid, number: usize) {
-        self.highlighting_region(self.tcx.mk_re_var(vid), number)
+        self.highlighting_region(ty::Region::new_var(self.tcx, vid), number)
     }
 
     /// Returns `Some(n)` with the number to use for the given region, if any.
@@ -2303,7 +2303,7 @@ impl<'a, 'tcx> ty::TypeFolder<TyCtxt<'tcx>> for RegionFolder<'a, 'tcx> {
         };
         if let ty::ReLateBound(debruijn1, br) = *region {
             assert_eq!(debruijn1, ty::INNERMOST);
-            self.tcx.mk_re_late_bound(self.current_index, br)
+            ty::Region::new_late_bound(self.tcx, self.current_index, br)
         } else {
             region
         }
@@ -2415,7 +2415,8 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = ty::BrNamed(CRATE_DEF_ID.to_def_id(), name);
-                                return tcx.mk_re_late_bound(
+                                return ty::Region::new_late_bound(
+                                    tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
                                 );
@@ -2430,7 +2431,8 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = ty::BrNamed(def_id, name);
-                                return tcx.mk_re_late_bound(
+                                return ty::Region::new_late_bound(
+                                    tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
                                 );
@@ -2443,7 +2445,8 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = br.kind;
-                                return tcx.mk_re_late_bound(
+                                return ty::Region::new_late_bound(
+                                    tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
                                 );
@@ -2458,7 +2461,11 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                     start_or_continue(&mut self, "for<", ", ");
                     do_continue(&mut self, name);
                 }
-                tcx.mk_re_late_bound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind })
+                ty::Region::new_late_bound(
+                    tcx,
+                    ty::INNERMOST,
+                    ty::BoundRegion { var: br.var, kind },
+                )
             };
             let mut folder = RegionFolder {
                 tcx,
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 6a9686c017b..68be9f83ba8 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -15,14 +15,14 @@ use hir::def::DefKind;
 use polonius_engine::Atom;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::intern::Interned;
-use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
+use rustc_errors::{DiagnosticArgValue, ErrorGuaranteed, IntoDiagnosticArg, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::LangItem;
 use rustc_index::Idx;
 use rustc_macros::HashStable;
 use rustc_span::symbol::{kw, sym, Symbol};
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, VariantIdx, FIRST_VARIANT};
 use rustc_target::spec::abi::{self, Abi};
 use std::borrow::Cow;
@@ -1459,6 +1459,103 @@ impl ParamConst {
 #[rustc_pass_by_value]
 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
 
+impl<'tcx> Region<'tcx> {
+    #[inline]
+    pub fn new_early_bound(
+        tcx: TyCtxt<'tcx>,
+        early_bound_region: ty::EarlyBoundRegion,
+    ) -> Region<'tcx> {
+        tcx.intern_region(ty::ReEarlyBound(early_bound_region))
+    }
+
+    #[inline]
+    pub fn new_late_bound(
+        tcx: TyCtxt<'tcx>,
+        debruijn: ty::DebruijnIndex,
+        bound_region: ty::BoundRegion,
+    ) -> Region<'tcx> {
+        // Use a pre-interned one when possible.
+        if let ty::BoundRegion { var, kind: ty::BrAnon(None) } = bound_region
+            && let Some(inner) = tcx.lifetimes.re_late_bounds.get(debruijn.as_usize())
+            && let Some(re) = inner.get(var.as_usize()).copied()
+        {
+            re
+        } else {
+            tcx.intern_region(ty::ReLateBound(debruijn, bound_region))
+        }
+    }
+
+    #[inline]
+    pub fn new_free(
+        tcx: TyCtxt<'tcx>,
+        scope: DefId,
+        bound_region: ty::BoundRegionKind,
+    ) -> Region<'tcx> {
+        tcx.intern_region(ty::ReFree(ty::FreeRegion { scope, bound_region }))
+    }
+
+    #[inline]
+    pub fn new_var(tcx: TyCtxt<'tcx>, v: ty::RegionVid) -> Region<'tcx> {
+        // Use a pre-interned one when possible.
+        tcx.lifetimes
+            .re_vars
+            .get(v.as_usize())
+            .copied()
+            .unwrap_or_else(|| tcx.intern_region(ty::ReVar(v)))
+    }
+
+    #[inline]
+    pub fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderRegion) -> Region<'tcx> {
+        tcx.intern_region(ty::RePlaceholder(placeholder))
+    }
+
+    /// Constructs a `RegionKind::ReError` region.
+    #[track_caller]
+    pub fn new_error(tcx: TyCtxt<'tcx>, reported: ErrorGuaranteed) -> Region<'tcx> {
+        tcx.intern_region(ty::ReError(reported))
+    }
+
+    /// Constructs a `RegionKind::ReError` region and registers a `delay_span_bug` to ensure it
+    /// gets used.
+    #[track_caller]
+    pub fn new_error_misc(tcx: TyCtxt<'tcx>) -> Region<'tcx> {
+        Region::new_error_with_message(
+            tcx,
+            DUMMY_SP,
+            "RegionKind::ReError constructed but no error reported",
+        )
+    }
+
+    /// Constructs a `RegionKind::ReError` region and registers a `delay_span_bug` with the given
+    /// `msg` to ensure it gets used.
+    #[track_caller]
+    pub fn new_error_with_message<S: Into<MultiSpan>>(
+        tcx: TyCtxt<'tcx>,
+        span: S,
+        msg: &'static str,
+    ) -> Region<'tcx> {
+        let reported = tcx.sess.delay_span_bug(span, msg);
+        Region::new_error(tcx, reported)
+    }
+
+    /// Avoid this in favour of more specific `new_*` methods, where possible,
+    /// to avoid the cost of the `match`.
+    pub fn new_from_kind(tcx: TyCtxt<'tcx>, kind: RegionKind<'tcx>) -> Region<'tcx> {
+        match kind {
+            ty::ReEarlyBound(region) => Region::new_early_bound(tcx, region),
+            ty::ReLateBound(debruijn, region) => Region::new_late_bound(tcx, debruijn, region),
+            ty::ReFree(ty::FreeRegion { scope, bound_region }) => {
+                Region::new_free(tcx, scope, bound_region)
+            }
+            ty::ReStatic => tcx.lifetimes.re_static,
+            ty::ReVar(vid) => Region::new_var(tcx, vid),
+            ty::RePlaceholder(region) => Region::new_placeholder(tcx, region),
+            ty::ReErased => tcx.lifetimes.re_erased,
+            ty::ReError(reported) => Region::new_error(tcx, reported),
+        }
+    }
+}
+
 impl<'tcx> Deref for Region<'tcx> {
     type Target = RegionKind<'tcx>;
 
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index 463f639defe..d00fb754c64 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -142,7 +142,7 @@ impl<'tcx> Cx<'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = self.tcx.mk_re_late_bound(ty::INNERMOST, br);
+                let env_region = ty::Region::new_late_bound(self.tcx, ty::INNERMOST, br);
                 let closure_env_ty =
                     self.tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
                 let liberated_closure_env_ty = self.tcx.erase_late_bound_regions(
diff --git a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
index 1071b8fc702..0f3f8f1ac2c 100644
--- a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
@@ -96,7 +96,7 @@ pub(in crate::solve) fn replace_erased_lifetimes_with_bound_vars<'tcx>(
             let br =
                 ty::BoundRegion { var: ty::BoundVar::from_u32(counter), kind: ty::BrAnon(None) };
             counter += 1;
-            tcx.mk_re_late_bound(current_depth, br)
+            ty::Region::new_late_bound(tcx, current_depth, br)
         }
         // All free regions should be erased here.
         r => bug!("unexpected region: {r:?}"),
diff --git a/compiler/rustc_trait_selection/src/solve/canonicalize.rs b/compiler/rustc_trait_selection/src/solve/canonicalize.rs
index ff4bff10cc8..29bdb5ff67d 100644
--- a/compiler/rustc_trait_selection/src/solve/canonicalize.rs
+++ b/compiler/rustc_trait_selection/src/solve/canonicalize.rs
@@ -255,7 +255,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'_, 'tcx> {
             }),
         );
         let br = ty::BoundRegion { var, kind: BrAnon(None) };
-        self.interner().mk_re_late_bound(self.binder_index, br)
+        ty::Region::new_late_bound(self.interner(), self.binder_index, br)
     }
 
     fn fold_ty(&mut self, mut t: Ty<'tcx>) -> Ty<'tcx> {
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 51069897120..65af0bb1c4e 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -824,7 +824,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for BoundVarReplacer<'_, 'tcx> {
                 let universe = self.universe_for(debruijn);
                 let p = ty::PlaceholderRegion { universe, bound: br };
                 self.mapped_regions.insert(p, br);
-                self.infcx.tcx.mk_re_placeholder(p)
+                ty::Region::new_placeholder(self.infcx.tcx, p)
             }
             _ => r,
         }
@@ -945,7 +945,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
                         let db = ty::DebruijnIndex::from_usize(
                             self.universe_indices.len() - index + self.current_index.as_usize() - 1,
                         );
-                        self.interner().mk_re_late_bound(db, *replace_var)
+                        ty::Region::new_late_bound(self.interner(), db, *replace_var)
                     }
                     None => r1,
                 }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 0245dfd333b..4e961c3ee73 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -550,7 +550,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
                                 let bound_var = ty::BoundVariableKind::Region(kind);
                                 bound_vars.push(bound_var);
-                                tcx.mk_re_late_bound(
+                                ty::Region::new_late_bound(
+                                    tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion {
                                         var: ty::BoundVar::from_usize(bound_vars.len() - 1),
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index ed380f32b72..ac4f845a005 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -3027,7 +3027,7 @@ fn bind_generator_hidden_types_above<'tcx>(
                             kind: ty::BrAnon(None),
                         };
                         counter += 1;
-                        tcx.mk_re_late_bound(current_depth, br)
+                        ty::Region::new_late_bound(tcx, current_depth, br)
                     }
                     r => bug!("unexpected region: {r:?}"),
                 })
diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
index 1d3ea96666f..38f94c38861 100644
--- a/compiler/rustc_traits/src/chalk/db.rs
+++ b/compiler/rustc_traits/src/chalk/db.rs
@@ -727,7 +727,7 @@ fn bound_vars_for_item(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
                 var: ty::BoundVar::from_usize(substs.len()),
                 kind: ty::BrAnon(None),
             };
-            tcx.mk_re_late_bound(ty::INNERMOST, br).into()
+            ty::Region::new_late_bound(tcx, ty::INNERMOST, br).into()
         }
 
         ty::GenericParamDefKind::Const { .. } => tcx
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
index e447ab94f64..e6c6e0f13df 100644
--- a/compiler/rustc_traits/src/chalk/lowering.rs
+++ b/compiler/rustc_traits/src/chalk/lowering.rs
@@ -542,7 +542,8 @@ impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'t
     fn lower_into(self, interner: RustInterner<'tcx>) -> Region<'tcx> {
         let tcx = interner.tcx;
         match self.data(interner) {
-            chalk_ir::LifetimeData::BoundVar(var) => tcx.mk_re_late_bound(
+            chalk_ir::LifetimeData::BoundVar(var) => ty::Region::new_late_bound(
+                tcx,
                 ty::DebruijnIndex::from_u32(var.debruijn.depth()),
                 ty::BoundRegion {
                     var: ty::BoundVar::from_usize(var.index),
@@ -550,13 +551,16 @@ impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'t
                 },
             ),
             chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
-            chalk_ir::LifetimeData::Placeholder(p) => tcx.mk_re_placeholder(ty::Placeholder {
-                universe: ty::UniverseIndex::from_usize(p.ui.counter),
-                bound: ty::BoundRegion {
-                    var: ty::BoundVar::from_usize(p.idx),
-                    kind: ty::BoundRegionKind::BrAnon(None),
+            chalk_ir::LifetimeData::Placeholder(p) => ty::Region::new_placeholder(
+                tcx,
+                ty::Placeholder {
+                    universe: ty::UniverseIndex::from_usize(p.ui.counter),
+                    bound: ty::BoundRegion {
+                        var: ty::BoundVar::from_usize(p.idx),
+                        kind: ty::BoundRegionKind::BrAnon(None),
+                    },
                 },
-            }),
+            ),
             chalk_ir::LifetimeData::Static => tcx.lifetimes.re_static,
             chalk_ir::LifetimeData::Erased => tcx.lifetimes.re_erased,
             chalk_ir::LifetimeData::Phantom(void, _) => match *void {},
@@ -1051,7 +1055,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for NamedBoundVarSubstitutor<'a, 'tcx> {
                 ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) {
                     Some(_) => {
                         let new_br = ty::BoundRegion { var: br.var, kind: ty::BrAnon(None) };
-                        return self.tcx.mk_re_late_bound(index, new_br);
+                        return ty::Region::new_late_bound(self.tcx, index, new_br);
                     }
                     None => panic!("Missing `BrNamed`."),
                 },
@@ -1142,7 +1146,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ParamsSubstitutor<'tcx> {
                         var: ty::BoundVar::from_u32(*idx),
                         kind: ty::BrAnon(None),
                     };
-                    self.tcx.mk_re_late_bound(self.binder_index, br)
+                    ty::Region::new_late_bound(self.tcx, self.binder_index, br)
                 }
                 None => {
                     let idx = self.named_regions.len() as u32;
@@ -1151,7 +1155,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ParamsSubstitutor<'tcx> {
                         kind: ty::BrAnon(None),
                     };
                     self.named_regions.insert(_re.def_id, idx);
-                    self.tcx.mk_re_late_bound(self.binder_index, br)
+                    ty::Region::new_late_bound(self.tcx, self.binder_index, br)
                 }
             },
 
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 15c19104616..5b3ffc9fc36 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -81,7 +81,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_region = tcx.mk_re_late_bound(ty::INNERMOST, br);
+            let env_region = ty::Region::new_late_bound(tcx, ty::INNERMOST, br);
             let env_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
 
             let sig = sig.skip_binder();
@@ -106,7 +106,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_ty = tcx.mk_mut_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), ty);
+            let env_ty = tcx.mk_mut_ref(ty::Region::new_late_bound(tcx, ty::INNERMOST, br), ty);
 
             let pin_did = tcx.require_lang_item(LangItem::Pin, None);
             let pin_adt_ref = tcx.adt_def(pin_did);
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
index 52bc386cb00..190a7765ff1 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -287,12 +287,13 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ImplTraitInTraitFinder<'_, 'tcx> {
             let shifted_alias_ty = self.tcx.fold_regions(unshifted_alias_ty, |re, depth| {
                 if let ty::ReLateBound(index, bv) = re.kind() {
                     if depth != ty::INNERMOST {
-                        return self.tcx.mk_re_error_with_message(
+                        return ty::Region::new_error_with_message(
+                            self.tcx,
                             DUMMY_SP,
                             "we shouldn't walk non-predicate binders with `impl Trait`...",
                         );
                     }
-                    self.tcx.mk_re_late_bound(index.shifted_out_to_binder(self.depth), bv)
+                    ty::Region::new_late_bound(self.tcx, index.shifted_out_to_binder(self.depth), bv)
                 } else {
                     re
                 }