introduce `LateParamRegionKind`

4 files changed, 17 insertions, 9 deletions

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 e176fc58999..a6b504de3da 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -430,12 +430,12 @@ fn compare_method_predicate_entailment<'tcx>(
     Ok(())
 }
 
-struct RemapLateBound<'a, 'tcx> {
+struct RemapLateParam<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    mapping: &'a FxIndexMap<ty::BoundRegionKind, ty::BoundRegionKind>,
+    mapping: &'a FxIndexMap<ty::LateParamRegionKind, ty::LateParamRegionKind>,
 }
 
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
+impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateParam<'_, 'tcx> {
     fn cx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
@@ -445,7 +445,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
             ty::Region::new_late_param(
                 self.tcx,
                 fr.scope,
-                self.mapping.get(&fr.bound_region).copied().unwrap_or(fr.bound_region),
+                self.mapping.get(&fr.kind).copied().unwrap_or(fr.kind),
             )
         } else {
             r
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs
index 6eac4ac3baf..2b14594ea1b 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs
@@ -289,11 +289,16 @@ fn report_mismatched_rpitit_signature<'tcx>(
         tcx.fn_sig(trait_m_def_id).skip_binder().bound_vars(),
         tcx.fn_sig(impl_m_def_id).skip_binder().bound_vars(),
     )
-    .filter_map(|(impl_bv, trait_bv)| {
+    .enumerate()
+    .filter_map(|(idx, (impl_bv, trait_bv))| {
         if let ty::BoundVariableKind::Region(impl_bv) = impl_bv
             && let ty::BoundVariableKind::Region(trait_bv) = trait_bv
         {
-            Some((impl_bv, trait_bv))
+            let var = ty::BoundVar::from_usize(idx);
+            Some((
+                ty::LateParamRegionKind::from_bound(var, impl_bv),
+                ty::LateParamRegionKind::from_bound(var, trait_bv),
+            ))
         } else {
             None
         }
@@ -301,7 +306,7 @@ fn report_mismatched_rpitit_signature<'tcx>(
     .collect();
 
     let mut return_ty =
-        trait_m_sig.output().fold_with(&mut super::RemapLateBound { tcx, mapping: &mapping });
+        trait_m_sig.output().fold_with(&mut super::RemapLateParam { tcx, mapping: &mapping });
 
     if tcx.asyncness(impl_m_def_id).is_async() && tcx.asyncness(trait_m_def_id).is_async() {
         let ty::Alias(ty::Projection, future_ty) = return_ty.kind() else {
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 059b8dcd975..3cddc9642ba 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -2339,8 +2339,11 @@ fn lint_redundant_lifetimes<'tcx>(
     );
     // If we are in a function, add its late-bound lifetimes too.
     if matches!(def_kind, DefKind::Fn | DefKind::AssocFn) {
-        for var in tcx.fn_sig(owner_id).instantiate_identity().bound_vars() {
+        for (idx, var) in
+            tcx.fn_sig(owner_id).instantiate_identity().bound_vars().iter().enumerate()
+        {
             let ty::BoundVariableKind::Region(kind) = var else { continue };
+            let kind = ty::LateParamRegionKind::from_bound(ty::BoundVar::from_usize(idx), kind);
             lifetimes.push(ty::Region::new_late_param(tcx, owner_id.to_def_id(), kind));
         }
     }
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index 78057d5a997..b56222763d0 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -355,7 +355,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 ty::Region::new_late_param(
                     tcx,
                     scope.to_def_id(),
-                    ty::BoundRegionKind::Named(id.to_def_id(), name),
+                    ty::LateParamRegionKind::Named(id.to_def_id(), name),
                 )
 
                 // (*) -- not late-bound, won't change