rename `ReLateBound` to `ReBound`

other changes:
- `Region::new_late_bound` -> `Region::new_bound`
- `Region::is_late_bound` -> `Region::is_bound`

80 files changed, 192 insertions, 195 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index c4323fef935..8aef34d9e76 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -462,7 +462,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         // lifetimes without names with the value `'0`.
         if let ty::Ref(region, ..) = ty.kind() {
             match **region {
-                ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
+                ty::ReBound(_, ty::BoundRegion { kind: br, .. })
                 | ty::RePlaceholder(ty::PlaceholderRegion {
                     bound: ty::BoundRegion { kind: br, .. },
                     ..
@@ -482,7 +482,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         let region = if let ty::Ref(region, ..) = ty.kind() {
             match **region {
-                ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
+                ty::ReBound(_, ty::BoundRegion { kind: br, .. })
                 | ty::RePlaceholder(ty::PlaceholderRegion {
                     bound: ty::BoundRegion { kind: br, .. },
                     ..
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index d38cfbc54d7..9d6b0a0e91b 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -357,7 +357,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                 ty::BoundRegionKind::BrAnon => None,
             },
 
-            ty::ReLateBound(..)
+            ty::ReBound(..)
             | ty::ReVar(..)
             | ty::RePlaceholder(..)
             | ty::ReErased
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 7897a5a63ba..ae7f9c5244c 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -665,7 +665,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = ty::Region::new_late_bound(tcx, ty::INNERMOST, br);
+                let env_region = ty::Region::new_bound(tcx, ty::INNERMOST, br);
                 let closure_ty = tcx.closure_env_ty(def_id, args, env_region).unwrap();
 
                 // The "inputs" of the closure in the
diff --git a/compiler/rustc_hir_analysis/src/astconv/bounds.rs b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
index 3e700f2da86..cb9259998e3 100644
--- a/compiler/rustc_hir_analysis/src/astconv/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
@@ -350,7 +350,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
             let args =
                 candidate.skip_binder().args.extend_to(tcx, assoc_item.def_id, |param, _| {
                     let subst = match param.kind {
-                        ty::GenericParamDefKind::Lifetime => ty::Region::new_late_bound(
+                        ty::GenericParamDefKind::Lifetime => ty::Region::new_bound(
                             tcx,
                             ty::INNERMOST,
                             ty::BoundRegion {
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 2fcb45ef8aa..e7a2131011c 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -250,7 +250,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     var: ty::BoundVar::from_u32(index),
                     kind: ty::BrNamed(def_id, name),
                 };
-                ty::Region::new_late_bound(tcx, debruijn, br)
+                ty::Region::new_bound(tcx, debruijn, br)
             }
 
             Some(rbv::ResolvedArg::EarlyBound(def_id)) => {
@@ -1622,7 +1622,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 }
 
                 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-                    if r.is_late_bound() { self.tcx.lifetimes.re_erased } else { r }
+                    // FIXME(@lcnr): This is broken, erasing bound regions
+                    // impacts selection as it results in different types.
+                    if r.is_bound() { self.tcx.lifetimes.re_erased } else { r }
                 }
 
                 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
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 857515f971a..d3a383ff7c5 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -2345,7 +2345,7 @@ fn param_env_with_gat_bounds<'tcx>(
                     let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
                     let bound_var = ty::BoundVariableKind::Region(kind);
                     bound_vars.push(bound_var);
-                    ty::Region::new_late_bound(
+                    ty::Region::new_bound(
                         tcx,
                         ty::INNERMOST,
                         ty::BoundRegion {
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index c61719c1fd2..eb009b9368f 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -143,12 +143,12 @@ 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 = ty::Region::new_late_bound(
+            let region = ty::Region::new_bound(
                 tcx,
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon },
             );
-            let env_region = ty::Region::new_late_bound(
+            let env_region = ty::Region::new_bound(
                 tcx,
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrEnv },
@@ -411,7 +411,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                     1,
                     vec![Ty::new_imm_ref(
                         tcx,
-                        ty::Region::new_late_bound(tcx, ty::INNERMOST, br),
+                        ty::Region::new_bound(tcx, ty::INNERMOST, br),
                         param(0),
                     )],
                     Ty::new_projection(tcx, discriminant_def_id, tcx.mk_args(&[param(0).into()])),
@@ -465,11 +465,8 @@ 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 };
-                let param_ty = Ty::new_imm_ref(
-                    tcx,
-                    ty::Region::new_late_bound(tcx, ty::INNERMOST, br),
-                    param(0),
-                );
+                let param_ty =
+                    Ty::new_imm_ref(tcx, ty::Region::new_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 eb4491b89bf..729e9f2f1d1 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -763,7 +763,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for GATSubstCollector<'tcx> {
             ty::Alias(ty::Projection, p) if p.def_id == self.gat => {
                 for (idx, subst) in p.args.iter().enumerate() {
                     match subst.unpack() {
-                        GenericArgKind::Lifetime(lt) if !lt.is_late_bound() => {
+                        GenericArgKind::Lifetime(lt) if !lt.is_bound() => {
                             self.regions.insert((lt, idx));
                         }
                         GenericArgKind::Type(t) => {
diff --git a/compiler/rustc_hir_analysis/src/hir_wf_check.rs b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
index ca7679cfba0..d5fb4340e1c 100644
--- a/compiler/rustc_hir_analysis/src/hir_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
@@ -196,6 +196,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for EraseAllBoundRegions<'tcx> {
         self.tcx
     }
     fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
-        if r.is_late_bound() { self.tcx.lifetimes.re_erased } else { r }
+        // FIXME(@lcnr): only erase escaping bound regions!
+        if r.is_bound() { self.tcx.lifetimes.re_erased } else { r }
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/outlives/utils.rs b/compiler/rustc_hir_analysis/src/outlives/utils.rs
index a6410c944f7..85703c60c30 100644
--- a/compiler/rustc_hir_analysis/src/outlives/utils.rs
+++ b/compiler/rustc_hir_analysis/src/outlives/utils.rs
@@ -167,8 +167,8 @@ fn is_free_region(region: Region<'_>) -> bool {
         //     }
         //
         // The type above might generate a `T: 'b` bound, but we can
-        // ignore it. We can't put it on the struct header anyway.
-        ty::ReLateBound(..) => false,
+        // ignore it. We can't name this lifetime pn the struct header anyway.
+        ty::ReBound(..) => false,
 
         ty::ReError(_) => false,
 
diff --git a/compiler/rustc_hir_analysis/src/variance/constraints.rs b/compiler/rustc_hir_analysis/src/variance/constraints.rs
index 5f8b1ace68b..6c1efb6470e 100644
--- a/compiler/rustc_hir_analysis/src/variance/constraints.rs
+++ b/compiler/rustc_hir_analysis/src/variance/constraints.rs
@@ -419,9 +419,11 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
 
             ty::ReStatic => {}
 
-            ty::ReLateBound(..) => {
-                // Late-bound regions do not get substituted the same
-                // way early-bound regions do, so we skip them here.
+            ty::ReBound(..) => {
+                // Either a higher-ranked region inside of a type or a
+                // late-bound function parameter.
+                //
+                // We do not compute constraints for either of these.
             }
 
             ty::ReError(_) => {}
diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs
index b8a265d4971..1edc3efbc77 100644
--- a/compiler/rustc_hir_typeck/src/check.rs
+++ b/compiler/rustc_hir_typeck/src/check.rs
@@ -214,7 +214,7 @@ fn check_panic_info_fn(tcx: TyCtxt<'_>, fn_id: LocalDefId, fn_sig: ty::FnSig<'_>
     // build type `for<'a, 'b> fn(&'a PanicInfo<'b>) -> !`
     let panic_info_ty = tcx.type_of(panic_info_did).instantiate(
         tcx,
-        &[ty::GenericArg::from(ty::Region::new_late_bound(
+        &[ty::GenericArg::from(ty::Region::new_bound(
             tcx,
             ty::INNERMOST,
             ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrAnon },
@@ -222,7 +222,7 @@ fn check_panic_info_fn(tcx: TyCtxt<'_>, fn_id: LocalDefId, fn_sig: ty::FnSig<'_>
     );
     let panic_info_ref_ty = Ty::new_imm_ref(
         tcx,
-        ty::Region::new_late_bound(
+        ty::Region::new_bound(
             tcx,
             ty::INNERMOST,
             ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon },
diff --git a/compiler/rustc_hir_typeck/src/writeback.rs b/compiler/rustc_hir_typeck/src/writeback.rs
index 896aacc6993..2dfe7272673 100644
--- a/compiler/rustc_hir_typeck/src/writeback.rs
+++ b/compiler/rustc_hir_typeck/src/writeback.rs
@@ -784,7 +784,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for EraseEarlyRegions<'tcx> {
         }
     }
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        if r.is_late_bound() { r } else { self.tcx.lifetimes.re_erased }
+        if r.is_bound() { r } else { self.tcx.lifetimes.re_erased }
     }
 }
 
@@ -822,7 +822,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Resolver<'cx, 'tcx> {
     }
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
+        debug_assert!(!r.is_bound(), "Should not be resolving bound region.");
         self.fcx.tcx.lifetimes.re_erased
     }
 
diff --git a/compiler/rustc_infer/src/errors/note_and_explain.rs b/compiler/rustc_infer/src/errors/note_and_explain.rs
index 57bc14ebcb3..869878420ae 100644
--- a/compiler/rustc_infer/src/errors/note_and_explain.rs
+++ b/compiler/rustc_infer/src/errors/note_and_explain.rs
@@ -73,8 +73,11 @@ impl<'a> DescriptionCtx<'a> {
             // ReFree rather than dumping Debug output on the user.
             //
             // We shouldn't really be having unification failures with ReVar
-            // and ReLateBound though.
-            ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => {
+            // and ReBound though.
+            //
+            // FIXME(@lcnr): figure out why we `ReBound` have to handle `ReBound`
+            // here, this feels somewhat off.
+            ty::ReVar(_) | ty::ReBound(..) | ty::ReErased => {
                 (alt_span, "revar", format!("{region:?}"))
             }
         };
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index 0e2f9ba70fe..ff8e354f53d 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -232,7 +232,7 @@ impl CanonicalizeMode for CanonicalizeUserTypeAnnotation {
         match *r {
             ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReErased | ty::ReStatic | ty::ReError(_) => r,
             ty::ReVar(_) => canonicalizer.canonical_var_for_region_in_root_universe(r),
-            ty::RePlaceholder(..) | ty::ReLateBound(..) => {
+            ty::RePlaceholder(..) | ty::ReBound(..) => {
                 // We only expect region names that the user can type.
                 bug!("unexpected region in query response: `{:?}`", r)
             }
@@ -343,7 +343,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(index, ..) => {
+            ty::ReBound(index, ..) => {
                 if index >= self.binder_index {
                     bug!("escaping late-bound region during canonicalization");
                 } else {
@@ -776,7 +776,7 @@ 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 };
-        ty::Region::new_late_bound(self.interner(), self.binder_index, br)
+        ty::Region::new_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/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index ed101082130..d911e28484c 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -460,7 +460,7 @@ impl<'tcx> InferCtxt<'tcx> {
                 }
                 GenericArgKind::Lifetime(result_value) => {
                     // e.g., here `result_value` might be `'?1` in the example above...
-                    if let ty::ReLateBound(debruijn, br) = *result_value {
+                    if let ty::ReBound(debruijn, br) = *result_value {
                         // ... in which case we would set `canonical_vars[0]` to `Some('static)`.
 
                         // We only allow a `ty::INNERMOST` index in substitutions.
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 26d071a0139..07155f8f74f 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -175,10 +175,10 @@ pub(super) fn note_and_explain_region<'tcx>(
         ty::ReError(_) => return,
 
         // We shouldn't really be having unification failures with ReVar
-        // and ReLateBound though.
-        ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => {
-            (format!("lifetime `{region}`"), alt_span)
-        }
+        // and ReBound though.
+        //
+        // FIXME(@lcnr): Figure out whether this is reachable and if so, why.
+        ty::ReVar(_) | ty::ReBound(..) | ty::ReErased => (format!("lifetime `{region}`"), alt_span),
     };
 
     emit_msg_span(err, prefix, description, span, suffix);
@@ -1285,7 +1285,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                         if lifetimes.0 != lifetimes.1 {
                             values.0.push_highlighted(l1);
                             values.1.push_highlighted(l2);
-                        } else if lifetimes.0.is_late_bound() {
+                        } else if lifetimes.0.is_bound() {
                             values.0.push_normal(l1);
                             values.1.push_normal(l2);
                         } else {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
index fe18d00293a..f0b33d30e2c 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
@@ -572,8 +572,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
                 if let ty::Ref(expected_region, _, _) = expected.kind()
                     && let ty::Ref(found_region, _, _) = found.kind()
-                    && expected_region.is_late_bound()
-                    && !found_region.is_late_bound()
+                    && expected_region.is_bound()
+                    && !found_region.is_bound()
                     && let hir::TyKind::Infer = arg_hir.kind
                 {
                     // If the expected region is late bound, the found region is not, and users are asking compiler
diff --git a/compiler/rustc_infer/src/infer/freshen.rs b/compiler/rustc_infer/src/infer/freshen.rs
index 35204478c54..e212547eaaf 100644
--- a/compiler/rustc_infer/src/infer/freshen.rs
+++ b/compiler/rustc_infer/src/infer/freshen.rs
@@ -110,7 +110,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for TypeFreshener<'a, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(..) => {
+            ty::ReBound(..) => {
                 // leave bound regions alone
                 r
             }
diff --git a/compiler/rustc_infer/src/infer/generalize.rs b/compiler/rustc_infer/src/infer/generalize.rs
index 17fe3aa7b44..84891022720 100644
--- a/compiler/rustc_infer/src/infer/generalize.rs
+++ b/compiler/rustc_infer/src/infer/generalize.rs
@@ -327,7 +327,7 @@ where
         match *r {
             // Never make variables for regions bound within the type itself,
             // nor for erased regions.
-            ty::ReLateBound(..) | ty::ReErased => {
+            ty::ReBound(..) | ty::ReErased => {
                 return Ok(r);
             }
 
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 bee0a978ad0..4ff9d749422 100644
--- a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
+++ b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
@@ -16,8 +16,8 @@ use rustc_data_structures::intern::Interned;
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{ReBound, RePlaceholder, ReVar};
 use rustc_middle::ty::{ReEarlyBound, ReErased, ReError, ReFree, ReStatic};
-use rustc_middle::ty::{ReLateBound, RePlaceholder, ReVar};
 use rustc_middle::ty::{Region, RegionVid};
 use rustc_span::Span;
 use std::fmt;
@@ -378,7 +378,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                     // so it doesn't really matter if it's shorter or longer than an empty region
                     ReError(_) => false,
 
-                    ReLateBound(..) | ReErased => {
+                    ReBound(..) | ReErased => {
                         bug!("cannot relate region: {:?}", a);
                     }
 
@@ -411,7 +411,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                     // so it doesn't really matter if it's shorter or longer than an empty region
                     ReError(_) => false,
 
-                    ReLateBound(..) | ReErased => {
+                    ReBound(..) | ReErased => {
                         bug!("cannot relate region: {:?}", b);
                     }
 
@@ -478,7 +478,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
     #[instrument(level = "trace", skip(self), ret)]
     fn lub_concrete_regions(&self, a: Region<'tcx>, b: Region<'tcx>) -> Region<'tcx> {
         match (*a, *b) {
-            (ReLateBound(..), _) | (_, ReLateBound(..)) | (ReErased, _) | (_, ReErased) => {
+            (ReBound(..), _) | (_, ReBound(..)) | (ReErased, _) | (_, ReErased) => {
                 bug!("cannot relate region: LUB({:?}, {:?})", a, b);
             }
 
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index 7a5dec22fe0..7a792d30cc7 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -432,7 +432,7 @@ where
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
         match *r {
             // ignore bound regions, keep visiting
-            ty::ReLateBound(_, _) => ControlFlow::Continue(()),
+            ty::ReBound(_, _) => ControlFlow::Continue(()),
             _ => {
                 (self.op)(r);
                 ControlFlow::Continue(())
diff --git a/compiler/rustc_infer/src/infer/outlives/components.rs b/compiler/rustc_infer/src/infer/outlives/components.rs
index 38819e8ad8a..f867876a2e6 100644
--- a/compiler/rustc_infer/src/infer/outlives/components.rs
+++ b/compiler/rustc_infer/src/infer/outlives/components.rs
@@ -213,8 +213,8 @@ pub(super) fn compute_alias_components_recursive<'tcx>(
                 compute_components(tcx, ty, out, visited);
             }
             GenericArgKind::Lifetime(lt) => {
-                // Ignore late-bound regions.
-                if !lt.is_late_bound() {
+                // Ignore higher ranked regions.
+                if !lt.is_bound() {
                     out.push(Component::Region(lt));
                 }
             }
@@ -241,8 +241,8 @@ fn compute_components_recursive<'tcx>(
                 compute_components(tcx, ty, out, visited);
             }
             GenericArgKind::Lifetime(lt) => {
-                // Ignore late-bound regions.
-                if !lt.is_late_bound() {
+                // Ignore higher ranked regions.
+                if !lt.is_bound() {
                     out.push(Component::Region(lt));
                 }
             }
diff --git a/compiler/rustc_infer/src/infer/outlives/for_liveness.rs b/compiler/rustc_infer/src/infer/outlives/for_liveness.rs
index 398ac94ee36..2db8579af52 100644
--- a/compiler/rustc_infer/src/infer/outlives/for_liveness.rs
+++ b/compiler/rustc_infer/src/infer/outlives/for_liveness.rs
@@ -37,7 +37,7 @@ where
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
         match *r {
             // ignore bound regions, keep visiting
-            ty::ReLateBound(_, _) => ControlFlow::Continue(()),
+            ty::ReBound(_, _) => ControlFlow::Continue(()),
             _ => {
                 (self.op)(r);
                 ControlFlow::Continue(())
diff --git a/compiler/rustc_infer/src/infer/outlives/test_type_match.rs b/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
index 6f973ee37f5..959b34aa145 100644
--- a/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
+++ b/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
@@ -48,7 +48,7 @@ pub fn extract_verify_if_eq<'tcx>(
     let verify_if_eq = verify_if_eq_b.skip_binder();
     m.relate(verify_if_eq.ty, test_ty).ok()?;
 
-    if let ty::RegionKind::ReLateBound(depth, br) = verify_if_eq.bound.kind() {
+    if let ty::RegionKind::ReBound(depth, br) = verify_if_eq.bound.kind() {
         assert!(depth == ty::INNERMOST);
         match m.map.get(&br) {
             Some(&r) => Some(r),
@@ -177,7 +177,7 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstHigherRankedOutlives<'tcx> {
         value: ty::Region<'tcx>,
     ) -> RelateResult<'tcx, ty::Region<'tcx>> {
         debug!("self.pattern_depth = {:?}", self.pattern_depth);
-        if let ty::RegionKind::ReLateBound(depth, br) = pattern.kind()
+        if let ty::RegionKind::ReBound(depth, br) = pattern.kind()
             && depth == self.pattern_depth
         {
             self.bind(br, value)
diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
index 3fa9a7333a4..de142f05fb7 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
@@ -16,7 +16,7 @@ use rustc_index::IndexVec;
 use rustc_middle::infer::unify_key::{RegionVidKey, UnifiedRegion};
 use rustc_middle::ty::ReStatic;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::ty::{ReLateBound, ReVar};
+use rustc_middle::ty::{ReBound, ReVar};
 use rustc_middle::ty::{Region, RegionVid};
 use rustc_span::Span;
 
@@ -531,7 +531,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         debug!("origin = {:#?}", origin);
 
         match (*sub, *sup) {
-            (ReLateBound(..), _) | (_, ReLateBound(..)) => {
+            (ReBound(..), _) | (_, ReBound(..)) => {
                 span_bug!(origin.span(), "cannot relate bound region: {:?} <= {:?}", sub, sup);
             }
             (_, ReStatic) => {
@@ -667,7 +667,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
             | ty::ReError(_) => ty::UniverseIndex::ROOT,
             ty::RePlaceholder(placeholder) => placeholder.universe,
             ty::ReVar(vid) => self.var_universe(vid),
-            ty::ReLateBound(..) => bug!("universe(): encountered bound region {:?}", region),
+            ty::ReBound(..) => bug!("universe(): encountered bound region {:?}", region),
         }
     }
 
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index 3c566e0dd6d..8cee13ce4ec 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -340,7 +340,7 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
                 // consider this as evidence that `T: 'static`, but
                 // I'm a bit wary of such constructions and so for now
                 // I want to be conservative. --nmatsakis
-                if r_min.is_late_bound() {
+                if r_min.is_bound() {
                     return;
                 }
 
@@ -351,7 +351,7 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
                         .into_iter()
                         .filter_map(|component| match component {
                             Component::Region(r) => {
-                                if r.is_late_bound() {
+                                if r.is_bound() {
                                     None
                                 } else {
                                     Some(ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index 64b63f4c5eb..5a957d2c26d 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -63,7 +63,7 @@ impl CanonicalVarValues<'_> {
     pub fn is_identity(&self) -> bool {
         self.var_values.iter().enumerate().all(|(bv, arg)| match arg.unpack() {
             ty::GenericArgKind::Lifetime(r) => {
-                matches!(*r, ty::ReLateBound(ty::INNERMOST, br) if br.var.as_usize() == bv)
+                matches!(*r, ty::ReBound(ty::INNERMOST, br) if br.var.as_usize() == bv)
             }
             ty::GenericArgKind::Type(ty) => {
                 matches!(*ty.kind(), ty::Bound(ty::INNERMOST, bt) if bt.var.as_usize() == bv)
@@ -79,7 +79,7 @@ impl CanonicalVarValues<'_> {
         for arg in self.var_values {
             match arg.unpack() {
                 ty::GenericArgKind::Lifetime(r) => {
-                    if let ty::ReLateBound(ty::INNERMOST, br) = *r
+                    if let ty::ReBound(ty::INNERMOST, br) = *r
                         && var == br.var
                     {
                         var = var + 1;
@@ -389,7 +389,7 @@ impl<'tcx> CanonicalVarValues<'tcx> {
                                 var: ty::BoundVar::from_usize(i),
                                 kind: ty::BrAnon,
                             };
-                            ty::Region::new_late_bound(tcx, ty::INNERMOST, br).into()
+                            ty::Region::new_bound(tcx, ty::INNERMOST, br).into()
                         }
                         CanonicalVarKind::Effect => ty::Const::new_bound(
                             tcx,
diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs
index 041a63776d1..92d1fcc7ed2 100644
--- a/compiler/rustc_middle/src/infer/unify_key.rs
+++ b/compiler/rustc_middle/src/infer/unify_key.rs
@@ -58,8 +58,7 @@ impl<'tcx> UnifyValue for UnifiedRegion<'tcx> {
 
     fn unify_values(value1: &Self, value2: &Self) -> Result<Self, NoError> {
         // We pick the value of the least universe because it is compatible with more variables.
-        // This is *not* necessary for soundness, but it allows more region variables to be
-        // resolved to the said value.
+        // This is *not* necessary for completeness.
         #[cold]
         fn min_universe<'tcx>(r1: Region<'tcx>, r2: Region<'tcx>) -> Region<'tcx> {
             cmp::min_by_key(r1, r2, |r| match r.kind() {
@@ -69,7 +68,7 @@ impl<'tcx> UnifyValue for UnifiedRegion<'tcx> {
                 | ty::ReEarlyBound(..)
                 | ty::ReError(_) => ty::UniverseIndex::ROOT,
                 ty::RePlaceholder(placeholder) => placeholder.universe,
-                ty::ReVar(..) | ty::ReLateBound(..) => bug!("not a universal region"),
+                ty::ReVar(..) | ty::ReBound(..) => bug!("not a universal region"),
             })
         }
 
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index 0540eb0efd6..d609965f36f 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -416,7 +416,7 @@ impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
         let inner = tcx.fold_regions(ty, |r, depth| match r.kind() {
             ty::ReVar(vid) => {
                 let br = ty::BoundRegion { var: ty::BoundVar::new(vid.index()), kind: ty::BrAnon };
-                ty::Region::new_late_bound(tcx, depth, br)
+                ty::Region::new_bound(tcx, depth, br)
             }
             _ => bug!("unexpected region in ClosureOutlivesSubjectTy: {r:?}"),
         });
@@ -430,7 +430,7 @@ impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
         mut map: impl FnMut(ty::RegionVid) -> ty::Region<'tcx>,
     ) -> Ty<'tcx> {
         tcx.fold_regions(self.inner, |r, depth| match r.kind() {
-            ty::ReLateBound(debruijn, br) => {
+            ty::ReBound(debruijn, br) => {
                 debug_assert_eq!(debruijn, depth);
                 map(ty::RegionVid::new(br.var.index()))
             }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 551c4a15dd0..1598d05251d 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -327,7 +327,7 @@ pub struct CommonLifetimes<'tcx> {
     pub re_vars: Vec<Region<'tcx>>,
 
     /// Pre-interned values of the form:
-    /// `ReLateBound(DebruijnIndex(i), BoundRegion { var: v, kind: BrAnon })`
+    /// `ReBound(DebruijnIndex(i), BoundRegion { var: v, kind: BrAnon })`
     /// for small values of `i` and `v`.
     pub re_late_bounds: Vec<Vec<Region<'tcx>>>,
 }
@@ -402,7 +402,7 @@ impl<'tcx> CommonLifetimes<'tcx> {
             .map(|i| {
                 (0..NUM_PREINTERNED_RE_LATE_BOUNDS_V)
                     .map(|v| {
-                        mk(ty::ReLateBound(
+                        mk(ty::ReBound(
                             ty::DebruijnIndex::from(i),
                             ty::BoundRegion { var: ty::BoundVar::from(v), kind: ty::BrAnon },
                         ))
diff --git a/compiler/rustc_middle/src/ty/erase_regions.rs b/compiler/rustc_middle/src/ty/erase_regions.rs
index 3371ea3bec8..cfd36fd8c7c 100644
--- a/compiler/rustc_middle/src/ty/erase_regions.rs
+++ b/compiler/rustc_middle/src/ty/erase_regions.rs
@@ -53,16 +53,11 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RegionEraserVisitor<'tcx> {
     }
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        // because late-bound regions affect subtyping, we can't
-        // erase the bound/free distinction, but we can replace
-        // all free regions with 'erased.
-        //
-        // Note that we *CAN* replace early-bound regions -- the
-        // type system never "sees" those, they get substituted
-        // away. In codegen, they will always be erased to 'erased
-        // whenever a substitution occurs.
+        // We must not erase bound regions. `for<'a> fn(&'a ())` and
+        // `fn(&'free ())` are different types: they may implement different
+        // traits and have a different `TypeId`.
         match *r {
-            ty::ReLateBound(..) => r,
+            ty::ReBound(..) => r,
             _ => self.tcx.lifetimes.re_erased,
         }
     }
diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs
index ec36bdc5a51..a2e709165d5 100644
--- a/compiler/rustc_middle/src/ty/flags.rs
+++ b/compiler/rustc_middle/src/ty/flags.rs
@@ -294,7 +294,7 @@ impl FlagComputation {
 
     fn add_region(&mut self, r: ty::Region<'_>) {
         self.add_flags(r.type_flags());
-        if let ty::ReLateBound(debruijn, _) = *r {
+        if let ty::ReBound(debruijn, _) = *r {
             self.add_bound_var(debruijn);
         }
     }
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index 00529a1e066..e8ff3b230cb 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -68,12 +68,10 @@ impl<'tcx> TyCtxt<'tcx> {
 /// Folds over the substructure of a type, visiting its component
 /// types and all regions that occur *free* within it.
 ///
-/// That is, `Ty` can contain function or method types that bind
-/// regions at the call site (`ReLateBound`), and occurrences of
-/// regions (aka "lifetimes") that are bound within a type are not
-/// visited by this folder; only regions that occur free will be
+/// That is, function pointer types and trait object can introduce
+/// new bound regions which are not visited by this visitors as
+/// they are not free; only regions that occur free will be
 /// visited by `fld_r`.
-
 pub struct RegionFolder<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
 
@@ -117,7 +115,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for RegionFolder<'a, 'tcx> {
     #[instrument(skip(self), level = "debug", ret)]
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(debruijn, _) if debruijn < self.current_index => {
+            ty::ReBound(debruijn, _) if debruijn < self.current_index => {
                 debug!(?self.current_index, "skipped bound region");
                 r
             }
@@ -205,15 +203,15 @@ where
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(debruijn, br) if debruijn == self.current_index => {
+            ty::ReBound(debruijn, br) if debruijn == self.current_index => {
                 let region = self.delegate.replace_region(br);
-                if let ty::ReLateBound(debruijn1, br) = *region {
-                    // If the callback returns a late-bound region,
+                if let ty::ReBound(debruijn1, br) = *region {
+                    // If the callback returns a bound region,
                     // that region should always use the INNERMOST
                     // debruijn index. Then we adjust it to the
                     // correct depth.
                     assert_eq!(debruijn1, ty::INNERMOST);
-                    ty::Region::new_late_bound(self.tcx, debruijn, br)
+                    ty::Region::new_bound(self.tcx, debruijn, br)
                 } else {
                     region
                 }
@@ -341,7 +339,7 @@ impl<'tcx> TyCtxt<'tcx> {
             value,
             FnMutDelegate {
                 regions: &mut |r: ty::BoundRegion| {
-                    ty::Region::new_late_bound(
+                    ty::Region::new_bound(
                         self,
                         ty::INNERMOST,
                         ty::BoundRegion { var: shift_bv(r.var), kind: r.kind },
@@ -388,7 +386,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     .or_insert_with(|| ty::BoundVariableKind::Region(ty::BrAnon))
                     .expect_region();
                 let br = ty::BoundRegion { var, kind };
-                ty::Region::new_late_bound(self.tcx, ty::INNERMOST, br)
+                ty::Region::new_bound(self.tcx, ty::INNERMOST, br)
             }
             fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
                 let entry = self.map.entry(bt.var);
@@ -454,9 +452,9 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Shifter<'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(debruijn, br) if debruijn >= self.current_index => {
+            ty::ReBound(debruijn, br) if debruijn >= self.current_index => {
                 let debruijn = debruijn.shifted_in(self.amount);
-                ty::Region::new_late_bound(self.tcx, debruijn, br)
+                ty::Region::new_bound(self.tcx, debruijn, br)
             }
             _ => r,
         }
@@ -496,8 +494,8 @@ pub fn shift_region<'tcx>(
     amount: u32,
 ) -> ty::Region<'tcx> {
     match *region {
-        ty::ReLateBound(debruijn, br) if amount > 0 => {
-            ty::Region::new_late_bound(tcx, debruijn.shifted_in(amount), br)
+        ty::ReBound(debruijn, br) if amount > 0 => {
+            ty::Region::new_bound(tcx, debruijn.shifted_in(amount), br)
         }
         _ => region,
     }
diff --git a/compiler/rustc_middle/src/ty/generic_args.rs b/compiler/rustc_middle/src/ty/generic_args.rs
index 41a1bf04e5f..c9607b2245a 100644
--- a/compiler/rustc_middle/src/ty/generic_args.rs
+++ b/compiler/rustc_middle/src/ty/generic_args.rs
@@ -843,7 +843,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for ArgFolder<'a, 'tcx> {
                     None => region_param_out_of_range(data, self.args),
                 }
             }
-            ty::ReLateBound(..)
+            ty::ReBound(..)
             | ty::ReFree(_)
             | ty::ReStatic
             | ty::RePlaceholder(_)
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs
index 8d895732dff..cabf2ab5dfe 100644
--- a/compiler/rustc_middle/src/ty/opaque_types.rs
+++ b/compiler/rustc_middle/src/ty/opaque_types.rs
@@ -102,8 +102,9 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseMapper<'tcx> {
             // Ignore bound regions and `'static` regions that appear in the
             // type, we only need to remap regions that reference lifetimes
             // from the function declaration.
-            // This would ignore `'r` in a type like `for<'r> fn(&'r u32)`.
-            ty::ReLateBound(..) | ty::ReStatic => return r,
+            //
+            // E.g. We ignore `'r` in a type like `for<'r> fn(&'r u32)`.
+            ty::ReBound(..) | ty::ReStatic => return r,
 
             // If regions have been erased (by writeback), don't try to unerase
             // them.
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index baf160bcc99..21bf5b4b3b1 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2160,7 +2160,7 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
         match *region {
             ty::ReEarlyBound(ref data) => data.has_name(),
 
-            ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
+            ty::ReBound(_, ty::BoundRegion { kind: br, .. })
             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
             | ty::RePlaceholder(ty::Placeholder {
                 bound: ty::BoundRegion { kind: br, .. }, ..
@@ -2234,7 +2234,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                     return Ok(());
                 }
             }
-            ty::ReLateBound(_, ty::BoundRegion { kind: br, .. })
+            ty::ReBound(_, ty::BoundRegion { kind: br, .. })
             | ty::ReFree(ty::FreeRegion { bound_region: br, .. })
             | ty::RePlaceholder(ty::Placeholder {
                 bound: ty::BoundRegion { kind: br, .. }, ..
@@ -2315,7 +2315,7 @@ impl<'a, 'tcx> ty::TypeFolder<TyCtxt<'tcx>> for RegionFolder<'a, 'tcx> {
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         let name = &mut self.name;
         let region = match *r {
-            ty::ReLateBound(db, br) if db >= self.current_index => {
+            ty::ReBound(db, br) if db >= self.current_index => {
                 *self.region_map.entry(br).or_insert_with(|| name(Some(db), self.current_index, br))
             }
             ty::RePlaceholder(ty::PlaceholderRegion {
@@ -2338,9 +2338,9 @@ impl<'a, 'tcx> ty::TypeFolder<TyCtxt<'tcx>> for RegionFolder<'a, 'tcx> {
             }
             _ => return r,
         };
-        if let ty::ReLateBound(debruijn1, br) = *region {
+        if let ty::ReBound(debruijn1, br) = *region {
             assert_eq!(debruijn1, ty::INNERMOST);
-            ty::Region::new_late_bound(self.tcx, self.current_index, br)
+            ty::Region::new_bound(self.tcx, self.current_index, br)
         } else {
             region
         }
@@ -2450,7 +2450,7 @@ 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 ty::Region::new_late_bound(
+                                return ty::Region::new_bound(
                                     tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
@@ -2466,7 +2466,7 @@ 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 ty::Region::new_late_bound(
+                                return ty::Region::new_bound(
                                     tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
@@ -2480,7 +2480,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = br.kind;
-                                return ty::Region::new_late_bound(
+                                return ty::Region::new_bound(
                                     tcx,
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
@@ -2496,11 +2496,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                     start_or_continue(self, "for<", ", ");
                     do_continue(self, name);
                 }
-                ty::Region::new_late_bound(
-                    tcx,
-                    ty::INNERMOST,
-                    ty::BoundRegion { var: br.var, kind },
-                )
+                ty::Region::new_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 44592b10d55..ca6ad4ea5c7 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1476,7 +1476,7 @@ impl<'tcx> Region<'tcx> {
     }
 
     #[inline]
-    pub fn new_late_bound(
+    pub fn new_bound(
         tcx: TyCtxt<'tcx>,
         debruijn: ty::DebruijnIndex,
         bound_region: ty::BoundRegion,
@@ -1488,7 +1488,7 @@ impl<'tcx> Region<'tcx> {
         {
             re
         } else {
-            tcx.intern_region(ty::ReLateBound(debruijn, bound_region))
+            tcx.intern_region(ty::ReBound(debruijn, bound_region))
         }
     }
 
@@ -1550,7 +1550,7 @@ impl<'tcx> Region<'tcx> {
     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::ReBound(debruijn, region) => Region::new_bound(tcx, debruijn, region),
             ty::ReFree(ty::FreeRegion { scope, bound_region }) => {
                 Region::new_free(tcx, scope, bound_region)
             }
@@ -1723,7 +1723,7 @@ impl<'tcx> Region<'tcx> {
         if self.has_name() {
             match *self {
                 ty::ReEarlyBound(ebr) => Some(ebr.name),
-                ty::ReLateBound(_, br) => br.kind.get_name(),
+                ty::ReBound(_, br) => br.kind.get_name(),
                 ty::ReFree(fr) => fr.bound_region.get_name(),
                 ty::ReStatic => Some(kw::StaticLifetime),
                 ty::RePlaceholder(placeholder) => placeholder.bound.kind.get_name(),
@@ -1745,7 +1745,7 @@ impl<'tcx> Region<'tcx> {
     pub fn has_name(self) -> bool {
         match *self {
             ty::ReEarlyBound(ebr) => ebr.has_name(),
-            ty::ReLateBound(_, br) => br.kind.is_named(),
+            ty::ReBound(_, br) => br.kind.is_named(),
             ty::ReFree(fr) => fr.bound_region.is_named(),
             ty::ReStatic => true,
             ty::ReVar(..) => false,
@@ -1771,8 +1771,8 @@ impl<'tcx> Region<'tcx> {
     }
 
     #[inline]
-    pub fn is_late_bound(self) -> bool {
-        matches!(*self, ty::ReLateBound(..))
+    pub fn is_bound(self) -> bool {
+        matches!(*self, ty::ReBound(..))
     }
 
     #[inline]
@@ -1783,7 +1783,7 @@ impl<'tcx> Region<'tcx> {
     #[inline]
     pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
         match *self {
-            ty::ReLateBound(debruijn, _) => debruijn >= index,
+            ty::ReBound(debruijn, _) => debruijn >= index,
             _ => false,
         }
     }
@@ -1814,7 +1814,7 @@ impl<'tcx> Region<'tcx> {
             ty::ReStatic => {
                 flags = flags | TypeFlags::HAS_FREE_REGIONS;
             }
-            ty::ReLateBound(..) => {
+            ty::ReBound(..) => {
                 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
             }
             ty::ReErased => {
diff --git a/compiler/rustc_middle/src/ty/typeck_results.rs b/compiler/rustc_middle/src/ty/typeck_results.rs
index e9240d1b268..1a76a8d350d 100644
--- a/compiler/rustc_middle/src/ty/typeck_results.rs
+++ b/compiler/rustc_middle/src/ty/typeck_results.rs
@@ -638,7 +638,7 @@ impl<'tcx> IsIdentity for CanonicalUserType<'tcx> {
                         },
 
                         GenericArgKind::Lifetime(r) => match *r {
-                            ty::ReLateBound(debruijn, br) => {
+                            ty::ReBound(debruijn, br) => {
                                 // We only allow a `ty::INNERMOST` index in substitutions.
                                 assert_eq!(debruijn, ty::INNERMOST);
                                 cvar == br.var
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index a251518d145..144e98f784a 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -468,7 +468,7 @@ impl<'tcx> TyCtxt<'tcx> {
         for arg in args {
             match arg.unpack() {
                 GenericArgKind::Lifetime(lt) => match (ignore_regions, lt.kind()) {
-                    (CheckRegions::Bound, ty::ReLateBound(di, reg)) => {
+                    (CheckRegions::Bound, ty::ReBound(di, reg)) => {
                         if !seen_late.insert((di, reg)) {
                             return Err(NotUniqueParam::DuplicateParam(lt.into()));
                         }
diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs
index 8fc5c030277..ee1cd76aa8b 100644
--- a/compiler/rustc_middle/src/ty/visit.rs
+++ b/compiler/rustc_middle/src/ty/visit.rs
@@ -204,7 +204,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
                 match *r {
-                    ty::ReLateBound(debruijn, _) if debruijn < self.outer_index => {
+                    ty::ReBound(debruijn, _) if debruijn < self.outer_index => {
                         ControlFlow::Continue(())
                     }
                     _ => {
@@ -337,7 +337,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ValidateBoundVars<'tcx> {
 
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
         match *r {
-            ty::ReLateBound(index, br) if index == self.binder_index => {
+            ty::ReBound(index, br) if index == self.binder_index => {
                 if self.bound_vars.len() <= br.var.as_usize() {
                     bug!("Not enough bound vars: {:?} not found in {:?}", br, self.bound_vars);
                 }
@@ -613,7 +613,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for LateBoundRegionsCollector {
     }
 
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-        if let ty::ReLateBound(debruijn, br) = *r {
+        if let ty::ReBound(debruijn, br) = *r {
             if debruijn == self.current_index {
                 self.regions.insert(br.kind);
             }
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index b6adb383fa6..bcd9140f0e1 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -132,7 +132,7 @@ impl<'tcx> Cx<'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = ty::Region::new_late_bound(self.tcx, ty::INNERMOST, br);
+                let env_region = ty::Region::new_bound(self.tcx, ty::INNERMOST, br);
                 let closure_env_ty =
                     self.tcx.closure_env_ty(closure_def_id, closure_args, env_region).unwrap();
                 let liberated_closure_env_ty = self.tcx.erase_late_bound_regions(
diff --git a/compiler/rustc_smir/src/rustc_smir/mod.rs b/compiler/rustc_smir/src/rustc_smir/mod.rs
index 27596c08f1c..d3bd87bb360 100644
--- a/compiler/rustc_smir/src/rustc_smir/mod.rs
+++ b/compiler/rustc_smir/src/rustc_smir/mod.rs
@@ -1696,7 +1696,7 @@ impl<'tcx> Stable<'tcx> for ty::RegionKind<'tcx> {
                 index: early_reg.index,
                 name: early_reg.name.to_string(),
             }),
-            ty::ReLateBound(db_index, bound_reg) => RegionKind::ReLateBound(
+            ty::ReBound(db_index, bound_reg) => RegionKind::ReBound(
                 db_index.as_u32(),
                 BoundRegion { var: bound_reg.var.as_u32(), kind: bound_reg.kind.stable(tables) },
             ),
diff --git a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
index 5ce188488ce..80dec80bf03 100644
--- a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
+++ b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
@@ -270,7 +270,7 @@ fn encode_region<'tcx>(
     // u6region[I[<region-disambiguator>][<region-index>]E] as vendor extended type
     let mut s = String::new();
     match region.kind() {
-        RegionKind::ReLateBound(debruijn, r) => {
+        RegionKind::ReBound(debruijn, r) => {
             s.push_str("u6regionI");
             // Debruijn index, which identifies the binder, as region disambiguator
             let num = debruijn.index() as u64;
@@ -282,6 +282,7 @@ fn encode_region<'tcx>(
             s.push('E');
             compress(dict, DictKey::Region(region), &mut s);
         }
+        // FIXME(@lcnr): Why is `ReEarlyBound` reachable here.
         RegionKind::ReEarlyBound(..) | RegionKind::ReErased => {
             s.push_str("u6region");
             compress(dict, DictKey::Region(region), &mut s);
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index ad3d291dfa0..01cbee3a715 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -319,9 +319,9 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             // shorter mangling of `L_`.
             ty::ReErased => 0,
 
-            // Late-bound lifetimes use indices starting at 1,
+            // Bound lifetimes use indices starting at 1,
             // see `BinderLevel` for more details.
-            ty::ReLateBound(debruijn, ty::BoundRegion { var, kind: ty::BrAnon }) => {
+            ty::ReBound(debruijn, ty::BoundRegion { var, kind: ty::BrAnon }) => {
                 let binder = &self.binders[self.binders.len() - 1 - debruijn.index()];
                 let depth = binder.lifetime_depths.start + var.as_u32();
 
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 839968b25a1..03b78681fa2 100644
--- a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
@@ -97,7 +97,7 @@ pub(in crate::solve) fn replace_erased_lifetimes_with_bound_vars<'tcx>(
         ty::ReErased => {
             let br = ty::BoundRegion { var: ty::BoundVar::from_u32(counter), kind: ty::BrAnon };
             counter += 1;
-            ty::Region::new_late_bound(tcx, current_depth, br)
+            ty::Region::new_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 377ae1b4e85..5f08bc0039a 100644
--- a/compiler/rustc_trait_selection/src/solve/canonicalize.rs
+++ b/compiler/rustc_trait_selection/src/solve/canonicalize.rs
@@ -222,7 +222,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'_, 'tcx> {
         }
 
         let kind = match *r {
-            ty::ReLateBound(..) => return r,
+            ty::ReBound(..) => return r,
 
             // We may encounter `ReStatic` in item signatures or the hidden type
             // of an opaque. `ReErased` should only be encountered in the hidden
@@ -278,7 +278,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'_, 'tcx> {
             var
         });
         let br = ty::BoundRegion { var, kind: BrAnon };
-        ty::Region::new_late_bound(self.interner(), self.binder_index, br)
+        ty::Region::new_bound(self.interner(), self.binder_index, br)
     }
 
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
index b3f9218d761..ae7f6ca2f7a 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
@@ -262,7 +262,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
                     }
                 }
                 GenericArgKind::Lifetime(r) => {
-                    if let ty::ReLateBound(debruijn, br) = *r {
+                    if let ty::ReBound(debruijn, br) = *r {
                         assert_eq!(debruijn, ty::INNERMOST);
                         opt_values[br.var] = Some(*original_value);
                     }
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index 8096d7969f3..dbf6749b523 100644
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -410,11 +410,11 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                         iter::zip(new_args.regions(), old_args.regions())
                     {
                         match (*new_region, *old_region) {
-                            // If both predicates have an `ReLateBound` (a HRTB) in the
+                            // If both predicates have an `ReBound` (a HRTB) in the
                             // same spot, we do nothing.
-                            (ty::ReLateBound(_, _), ty::ReLateBound(_, _)) => {}
+                            (ty::ReBound(_, _), ty::ReBound(_, _)) => {}
 
-                            (ty::ReLateBound(_, _), _) | (_, ty::ReVar(_)) => {
+                            (ty::ReBound(_, _), _) | (_, ty::ReVar(_)) => {
                                 // One of these is true:
                                 // The new predicate has a HRTB in a spot where the old
                                 // predicate does not (if they both had a HRTB, the previous
@@ -440,7 +440,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                                 // `user_computed_preds`.
                                 return false;
                             }
-                            (_, ty::ReLateBound(_, _)) | (ty::ReVar(_), _) => {
+                            (_, ty::ReBound(_, _)) | (ty::ReVar(_), _) => {
                                 // This is the opposite situation as the previous arm.
                                 // One of these is true:
                                 //
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 6b09bc89873..3afab24acb6 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -740,7 +740,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             }
 
             // We `erase_late_bound_regions` here because `make_subregion` does not handle
-            // `ReLateBound`, and we don't particularly care about the regions.
+            // `ReBound`, and we don't particularly care about the regions.
             let real_ty = self.tcx.erase_late_bound_regions(real_trait_pred.self_ty());
             if !self.can_eq(obligation.param_env, real_ty, arg_ty) {
                 continue;
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 471d10dbdbd..d03704c1d64 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -894,16 +894,16 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for BoundVarReplacer<'_, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
-            ty::ReLateBound(debruijn, _)
-                if debruijn.as_usize() + 1
-                    > self.current_index.as_usize() + self.universe_indices.len() =>
+            ty::ReBound(debruijn, _)
+                if debruijn.as_usize()
+                    >= self.current_index.as_usize() + self.universe_indices.len() =>
             {
                 bug!(
                     "Bound vars {r:#?} outside of `self.universe_indices`: {:#?}",
                     self.universe_indices
                 );
             }
-            ty::ReLateBound(debruijn, br) if debruijn >= self.current_index => {
+            ty::ReBound(debruijn, br) if debruijn >= self.current_index => {
                 let universe = self.universe_for(debruijn);
                 let p = ty::PlaceholderRegion { universe, bound: br };
                 self.mapped_regions.insert(p, br);
@@ -1034,7 +1034,7 @@ 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,
                         );
-                        ty::Region::new_late_bound(self.interner(), db, *replace_var)
+                        ty::Region::new_bound(self.interner(), db, *replace_var)
                     }
                     None => r1,
                 }
diff --git a/compiler/rustc_trait_selection/src/traits/query/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
index 2e31b560b38..dba00ce0154 100644
--- a/compiler/rustc_trait_selection/src/traits/query/normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
@@ -150,7 +150,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for MaxEscapingBoundVarVisitor {
     #[inline]
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
         match *r {
-            ty::ReLateBound(debruijn, _) if debruijn > self.outer_index => {
+            ty::ReBound(debruijn, _) if debruijn > self.outer_index => {
                 self.escaping =
                     self.escaping.max(debruijn.as_usize() - self.outer_index.as_usize());
             }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 4bfa341e333..6205ef05220 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -592,7 +592,7 @@ 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);
-                            ty::Region::new_late_bound(
+                            ty::Region::new_bound(
                                 tcx,
                                 ty::INNERMOST,
                                 ty::BoundRegion {
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 08208cc6047..6d13f4dbc99 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -3103,7 +3103,7 @@ fn bind_coroutine_hidden_types_above<'tcx>(
                                 kind: ty::BrAnon,
                             };
                             counter += 1;
-                            ty::Region::new_late_bound(tcx, current_depth, br)
+                            ty::Region::new_bound(tcx, current_depth, br)
                         }
                         r => bug!("unexpected region: {r:?}"),
                     })
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index fcf6626bbf0..38f2d616f9a 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -82,7 +82,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_region = ty::Region::new_late_bound(tcx, ty::INNERMOST, br);
+            let env_region = ty::Region::new_bound(tcx, ty::INNERMOST, br);
             let env_ty = tcx.closure_env_ty(def_id, args, env_region).unwrap();
 
             let sig = sig.skip_binder();
@@ -107,8 +107,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_ty =
-                Ty::new_mut_ref(tcx, ty::Region::new_late_bound(tcx, ty::INNERMOST, br), ty);
+            let env_ty = Ty::new_mut_ref(tcx, ty::Region::new_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 abf3e108ed4..2b262cfdebd 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -195,7 +195,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ImplTraitInTraitFinder<'_, 'tcx> {
             // bounds of the RPITIT. Shift these binders back out when
             // constructing the top-level projection predicate.
             let shifted_alias_ty = self.tcx.fold_regions(unshifted_alias_ty, |re, depth| {
-                if let ty::ReLateBound(index, bv) = re.kind() {
+                if let ty::ReBound(index, bv) = re.kind() {
                     if depth != ty::INNERMOST {
                         return ty::Region::new_error_with_message(
                             self.tcx,
@@ -203,7 +203,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ImplTraitInTraitFinder<'_, 'tcx> {
                             "we shouldn't walk non-predicate binders with `impl Trait`...",
                         );
                     }
-                    ty::Region::new_late_bound(
+                    ty::Region::new_bound(
                         self.tcx,
                         index.shifted_out_to_binder(self.depth),
                         bv,
diff --git a/compiler/rustc_type_ir/src/flags.rs b/compiler/rustc_type_ir/src/flags.rs
index 8472a084505..a7dda717517 100644
--- a/compiler/rustc_type_ir/src/flags.rs
+++ b/compiler/rustc_type_ir/src/flags.rs
@@ -85,10 +85,10 @@ bitflags! {
         const HAS_ERROR                   = 1 << 14;
 
         /// Does this have any region that "appears free" in the type?
-        /// Basically anything but `ReLateBound` and `ReErased`.
+        /// Basically anything but `ReBound` and `ReErased`.
         const HAS_FREE_REGIONS            = 1 << 15;
 
-        /// Does this have any `ReLateBound` regions?
+        /// Does this have any `ReBound` regions?
         const HAS_RE_LATE_BOUND           = 1 << 16;
         /// Does this have any `Bound` types?
         const HAS_TY_LATE_BOUND           = 1 << 17;
diff --git a/compiler/rustc_type_ir/src/region_kind.rs b/compiler/rustc_type_ir/src/region_kind.rs
index 69ed5badaea..fc9eaf63ac8 100644
--- a/compiler/rustc_type_ir/src/region_kind.rs
+++ b/compiler/rustc_type_ir/src/region_kind.rs
@@ -128,9 +128,16 @@ pub enum RegionKind<I: Interner> {
     /// parameters are substituted.
     ReEarlyBound(I::EarlyBoundRegion),
 
-    /// Region bound in a function scope, which will be substituted when the
-    /// function is called.
-    ReLateBound(DebruijnIndex, I::BoundRegion),
+    /// A higher-ranked region. These represent either late-bound function parameters
+    /// or bound variables from a `for<'a>`-binder.
+    ///
+    /// While inside of a function, e.g. during typeck, the late-bound function parameters
+    /// can be converted to `ReFree` by calling `tcx.liberate_late_bound_regions`.
+    ///
+    /// Bound regions inside of types **must not** be erased, as they impact trait
+    /// selection and the `TypeId` of that type. `for<'a> fn(&'a ())` and
+    /// `fn(&'static ())` are different types and have to be treated as such.
+    ReBound(DebruijnIndex, I::BoundRegion),
 
     /// When checking a function body, the types of all arguments and so forth
     /// that refer to bound region parameters are modified to refer to free
@@ -160,7 +167,7 @@ pub enum RegionKind<I: Interner> {
 const fn regionkind_discriminant<I: Interner>(value: &RegionKind<I>) -> usize {
     match value {
         ReEarlyBound(_) => 0,
-        ReLateBound(_, _) => 1,
+        ReBound(_, _) => 1,
         ReFree(_) => 2,
         ReStatic => 3,
         ReVar(_) => 4,
@@ -189,7 +196,7 @@ impl<I: Interner> PartialEq for RegionKind<I> {
         regionkind_discriminant(self) == regionkind_discriminant(other)
             && match (self, other) {
                 (ReEarlyBound(a_r), ReEarlyBound(b_r)) => a_r == b_r,
-                (ReLateBound(a_d, a_r), ReLateBound(b_d, b_r)) => a_d == b_d && a_r == b_r,
+                (ReBound(a_d, a_r), ReBound(b_d, b_r)) => a_d == b_d && a_r == b_r,
                 (ReFree(a_r), ReFree(b_r)) => a_r == b_r,
                 (ReStatic, ReStatic) => true,
                 (ReVar(a_r), ReVar(b_r)) => a_r == b_r,
@@ -218,8 +225,8 @@ impl<I: Interner> DebugWithInfcx<I> for RegionKind<I> {
         match this.data {
             ReEarlyBound(data) => write!(f, "ReEarlyBound({data:?})"),
 
-            ReLateBound(binder_id, bound_region) => {
-                write!(f, "ReLateBound({binder_id:?}, {bound_region:?})")
+            ReBound(binder_id, bound_region) => {
+                write!(f, "ReBound({binder_id:?}, {bound_region:?})")
             }
 
             ReFree(fr) => write!(f, "{fr:?}"),
@@ -258,7 +265,7 @@ where
             ReErased | ReStatic | ReError(_) => {
                 // No variant fields to hash for these ...
             }
-            ReLateBound(d, r) => {
+            ReBound(d, r) => {
                 d.hash_stable(hcx, hasher);
                 r.hash_stable(hcx, hasher);
             }
diff --git a/compiler/stable_mir/src/ty.rs b/compiler/stable_mir/src/ty.rs
index 5dfaa0fd891..bd3feef6018 100644
--- a/compiler/stable_mir/src/ty.rs
+++ b/compiler/stable_mir/src/ty.rs
@@ -62,7 +62,7 @@ pub struct Region {
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub enum RegionKind {
     ReEarlyBound(EarlyBoundRegion),
-    ReLateBound(DebruijnIndex, BoundRegion),
+    ReBound(DebruijnIndex, BoundRegion),
     ReStatic,
     RePlaceholder(Placeholder<BoundRegion>),
     ReErased,
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
index bdf6a0f6b23..eb946e82f39 100644
--- a/src/librustdoc/clean/auto_trait.rs
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -743,7 +743,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for RegionReplacer<'a, 'tcx> {
         match *r {
             // These are the regions that can be seen in the AST.
             ty::ReVar(vid) => self.vid_to_region.get(&vid).cloned().unwrap_or(r),
-            ty::ReEarlyBound(_) | ty::ReStatic | ty::ReLateBound(..) | ty::ReError(_) => r,
+            ty::ReEarlyBound(_) | ty::ReStatic | ty::ReBound(..) | ty::ReError(_) => r,
             r => bug!("unexpected region: {r:?}"),
         }
     }
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 1b7ca7bf7dd..d33e41dc2b3 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -286,11 +286,9 @@ pub(crate) fn clean_middle_region<'tcx>(region: ty::Region<'tcx>) -> Option<Life
     match *region {
         ty::ReStatic => Some(Lifetime::statik()),
         _ if !region.has_name() => None,
-        ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
-            Some(Lifetime(name))
-        }
+        ty::ReBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => Some(Lifetime(name)),
         ty::ReEarlyBound(ref data) => Some(Lifetime(data.name)),
-        ty::ReLateBound(..)
+        ty::ReBound(..)
         | ty::ReFree(..)
         | ty::ReVar(..)
         | ty::ReError(_)
@@ -1931,13 +1929,11 @@ fn clean_trait_object_lifetime_bound<'tcx>(
     match *region {
         ty::ReStatic => Some(Lifetime::statik()),
         ty::ReEarlyBound(region) if region.name != kw::Empty => Some(Lifetime(region.name)),
-        ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. })
-            if name != kw::Empty =>
-        {
+        ty::ReBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) if name != kw::Empty => {
             Some(Lifetime(name))
         }
         ty::ReEarlyBound(_)
-        | ty::ReLateBound(..)
+        | ty::ReBound(..)
         | ty::ReFree(_)
         | ty::ReVar(_)
         | ty::RePlaceholder(_)
diff --git a/src/tools/clippy/clippy_lints/src/eta_reduction.rs b/src/tools/clippy/clippy_lints/src/eta_reduction.rs
index fad8fbf0449..150b1c777db 100644
--- a/src/tools/clippy/clippy_lints/src/eta_reduction.rs
+++ b/src/tools/clippy/clippy_lints/src/eta_reduction.rs
@@ -247,8 +247,8 @@ fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure: ClosureArgs<'tcx>, call_sig:
 /// This is needed because rustc is unable to late bind early-bound regions in a function signature.
 fn has_late_bound_to_non_late_bound_regions(from_sig: FnSig<'_>, to_sig: FnSig<'_>) -> bool {
     fn check_region(from_region: Region<'_>, to_region: Region<'_>) -> bool {
-        matches!(from_region.kind(), RegionKind::ReLateBound(..))
-            && !matches!(to_region.kind(), RegionKind::ReLateBound(..))
+        matches!(from_region.kind(), RegionKind::ReBound(..))
+            && !matches!(to_region.kind(), RegionKind::ReBound(..))
     }
 
     fn check_subs(from_subs: &[GenericArg<'_>], to_subs: &[GenericArg<'_>]) -> bool {
diff --git a/src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs b/src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs
index 4d7a055dae1..d6fa742b796 100644
--- a/src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs
+++ b/src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs
@@ -168,7 +168,7 @@ impl<'tcx> PassByRefOrValue {
             match *ty.skip_binder().kind() {
                 ty::Ref(lt, ty, Mutability::Not) => {
                     match lt.kind() {
-                        RegionKind::ReLateBound(index, region)
+                        RegionKind::ReBound(index, region)
                             if index.as_u32() == 0 && output_regions.contains(&region) =>
                         {
                             continue;
diff --git a/src/tools/clippy/clippy_lints/src/ptr.rs b/src/tools/clippy/clippy_lints/src/ptr.rs
index 83863b92caf..c6ac96a4539 100644
--- a/src/tools/clippy/clippy_lints/src/ptr.rs
+++ b/src/tools/clippy/clippy_lints/src/ptr.rs
@@ -466,7 +466,7 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
                                     .filter_map(|arg| {
                                         arg.as_region().and_then(|lifetime| match lifetime.kind() {
                                             ty::ReEarlyBound(r) => Some(r.def_id),
-                                            ty::ReLateBound(_, r) => r.kind.get_id(),
+                                            ty::ReBound(_, r) => r.kind.get_id(),
                                             ty::ReFree(r) => r.bound_region.get_id(),
                                             ty::ReStatic
                                             | ty::ReVar(_)
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index 7eff93881b2..758aa40a2dd 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -890,7 +890,7 @@ pub fn for_each_top_level_late_bound_region<B>(
     impl<'tcx, B, F: FnMut(BoundRegion) -> ControlFlow<B>> TypeVisitor<TyCtxt<'tcx>> for V<F> {
         type BreakTy = B;
         fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-            if let RegionKind::ReLateBound(idx, bound) = r.kind()
+            if let RegionKind::ReBound(idx, bound) = r.kind()
                 && idx.as_u32() == self.index
             {
                 (self.f)(bound)
diff --git a/tests/ui/coroutine/issue-57084.rs b/tests/ui/coroutine/issue-57084.rs
index 95bed5b151e..e0aeae66735 100644
--- a/tests/ui/coroutine/issue-57084.rs
+++ b/tests/ui/coroutine/issue-57084.rs
@@ -1,5 +1,5 @@
 // This issue reproduces an ICE on compile (E.g. fails on 2018-12-19 nightly).
-// "cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(1)) <= '?1"
+// "cannot relate bound region: ReBound(DebruijnIndex(1), BrAnon(1)) <= '?1"
 // run-pass
 // edition:2018
 #![feature(coroutines,coroutine_trait)]
diff --git a/tests/ui/nll/closure-requirements/escape-argument-callee.stderr b/tests/ui/nll/closure-requirements/escape-argument-callee.stderr
index b3cb7813e19..a8f6559e425 100644
--- a/tests/ui/nll/closure-requirements/escape-argument-callee.stderr
+++ b/tests/ui/nll/closure-requirements/escape-argument-callee.stderr
@@ -6,7 +6,7 @@ LL |         let mut closure = expect_sig(|p, y| *p = y);
    |
    = note: defining type: test::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) mut &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) i32)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) mut &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) i32)),
                (),
            ]
 
diff --git a/tests/ui/nll/closure-requirements/escape-argument.stderr b/tests/ui/nll/closure-requirements/escape-argument.stderr
index 4f0156728ac..40f04bb6da6 100644
--- a/tests/ui/nll/closure-requirements/escape-argument.stderr
+++ b/tests/ui/nll/closure-requirements/escape-argument.stderr
@@ -6,7 +6,7 @@ LL |         let mut closure = expect_sig(|p, y| *p = y);
    |
    = note: defining type: test::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) mut &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) mut &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32, &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32)),
                (),
            ]
 
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr
index ccf56bf6f37..ef2cb4067d7 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-fail-no-postdom.stderr
@@ -6,7 +6,7 @@ LL |         |_outlives1, _outlives2, _outlives3, x, y| {
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&'?2 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?3 u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&'?2 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?3 u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?4
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-ref.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-ref.stderr
index a16433c9d37..db48a4ce70c 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-ref.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-ref.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) &'?2 u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) &'?2 u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?3
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr
index 9e0f16c0fc7..5ce3dae5a33 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-comparing-against-free.stderr
@@ -6,7 +6,7 @@ LL |     foo(cell, |cell_a, cell_x| {
    |
    = note: defining type: case1::{closure#0} with closure args [
                i32,
-               for<Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>)),
+               for<Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>)),
                (),
            ]
 
@@ -36,7 +36,7 @@ LL |     foo(cell, |cell_a, cell_x| {
    |
    = note: defining type: case2::{closure#0} with closure args [
                i32,
-               for<Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>)),
+               for<Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>)),
                (),
            ]
    = note: number of external vids: 2
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
index e4989e32155..ffd526d90af 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(&cell_a, &cell_b, |_outlives, x, y| {
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?2
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
index be35e62d070..726d0dc2a4c 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&'?2 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&'?2 &ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?3
diff --git a/tests/ui/nll/closure-requirements/propagate-approximated-val.stderr b/tests/ui/nll/closure-requirements/propagate-approximated-val.stderr
index 8880dd816a1..5a65c768448 100644
--- a/tests/ui/nll/closure-requirements/propagate-approximated-val.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-approximated-val.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(cell_a, cell_b, |outlives1, outlives2, x, y| {
    |
    = note: defining type: test::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?2 u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?2 u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?3
diff --git a/tests/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr b/tests/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
index 47774b63f81..0dd53f81ae1 100644
--- a/tests/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-despite-same-free-region.stderr
@@ -6,7 +6,7 @@ LL |         |_outlives1, _outlives2, x, y| {
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?2 u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?2 u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) u32>, std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?3
diff --git a/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr b/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
index 3404bb12827..f7a0ee9b18d 100644
--- a/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-no-bounds.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(&cell_a, &cell_b, |_outlives, x, y| {
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?1 u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?1 u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?2
diff --git a/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr b/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
index e40648912e3..fa9fa9e8f3c 100644
--- a/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
+++ b/tests/ui/nll/closure-requirements/propagate-fail-to-approximate-longer-wrong-bounds.stderr
@@ -6,7 +6,7 @@ LL |     establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y
    |
    = note: defining type: supply::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?1 u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) &'?2 u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReLateBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
+               for<Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) &'?1 u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 2, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) &'?2 u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 4, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) u32>, &ReBound(DebruijnIndex(0), BoundRegion { var: 5, kind: BrAnon }) std::cell::Cell<&ReBound(DebruijnIndex(0), BoundRegion { var: 3, kind: BrAnon }) u32>)),
                (),
            ]
    = note: late-bound region is '?3
diff --git a/tests/ui/nll/closure-requirements/return-wrong-bound-region.stderr b/tests/ui/nll/closure-requirements/return-wrong-bound-region.stderr
index 18fb7195d02..35e4a16c8da 100644
--- a/tests/ui/nll/closure-requirements/return-wrong-bound-region.stderr
+++ b/tests/ui/nll/closure-requirements/return-wrong-bound-region.stderr
@@ -6,7 +6,7 @@ LL |     expect_sig(|a, b| b); // ought to return `a`
    |
    = note: defining type: test::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) i32, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32)) -> &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) i32,
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((&ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) i32, &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) i32)) -> &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) i32,
                (),
            ]
 
diff --git a/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr b/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
index 59e29e9a420..0048eef6779 100644
--- a/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
+++ b/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.stderr
@@ -6,7 +6,7 @@ LL |     twice(cell, value, |a, b| invoke(a, b));
    |
    = note: defining type: generic::<T>::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) ()>>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) T)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) ()>>, &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) T)),
                (),
            ]
    = note: number of external vids: 2
@@ -28,7 +28,7 @@ LL |     twice(cell, value, |a, b| invoke(a, b));
    |
    = note: defining type: generic_fail::<T>::{closure#0} with closure args [
                i16,
-               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'?1 &ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) ()>>, &ReLateBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) T)),
+               for<Region(BrAnon), Region(BrAnon)> extern "rust-call" fn((std::option::Option<std::cell::Cell<&'?1 &ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrAnon }) ()>>, &ReBound(DebruijnIndex(0), BoundRegion { var: 1, kind: BrAnon }) T)),
                (),
            ]
    = note: late-bound region is '?2
diff --git a/tests/ui/where-clauses/higher-ranked-fn-type.verbose.stderr b/tests/ui/where-clauses/higher-ranked-fn-type.verbose.stderr
index 54afeaa7eda..782e7dc5e00 100644
--- a/tests/ui/where-clauses/higher-ranked-fn-type.verbose.stderr
+++ b/tests/ui/where-clauses/higher-ranked-fn-type.verbose.stderr
@@ -1,8 +1,8 @@
-error[E0277]: the trait bound `for<Region(BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b))> fn(&ReLateBound(DebruijnIndex(1), BoundRegion { var: 0, kind: BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b) }) ()): Foo` is not satisfied
+error[E0277]: the trait bound `for<Region(BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b))> fn(&ReBound(DebruijnIndex(1), BoundRegion { var: 0, kind: BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b) }) ()): Foo` is not satisfied
   --> $DIR/higher-ranked-fn-type.rs:20:5
    |
 LL |     called()
-   |     ^^^^^^ the trait `for<Region(BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b))> Foo` is not implemented for `fn(&ReLateBound(DebruijnIndex(1), BoundRegion { var: 0, kind: BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b) }) ())`
+   |     ^^^^^^ the trait `for<Region(BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b))> Foo` is not implemented for `fn(&ReBound(DebruijnIndex(1), BoundRegion { var: 0, kind: BrNamed(DefId(0:6 ~ higher_ranked_fn_type[9e51]::called::'b), 'b) }) ())`
    |
 help: this trait has no implementations, consider adding one
   --> $DIR/higher-ranked-fn-type.rs:6:1