Auto merge of #108020 - nnethercote:opt-mk_region, r=compiler-errors

Optimize `mk_region`

PR #107869 avoiding some interning under `mk_ty` by special-casing `Ty` variants with simple (integer) bodies. This PR does something similar for regions.

r? `@compiler-errors`

6 files changed, 49 insertions, 58 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 46dc4141e66..e5c176f19ea 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -234,7 +234,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     var: ty::BoundVar::from_u32(index),
                     kind: ty::BrNamed(def_id, name),
                 };
-                tcx.mk_region(ty::ReLateBound(debruijn, br))
+                tcx.mk_re_late_bound(debruijn, br)
             }
 
             Some(rl::Region::EarlyBound(def_id)) => {
@@ -242,15 +242,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local());
                 let generics = tcx.generics_of(item_def_id);
                 let index = generics.param_def_id_to_index[&def_id];
-                tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, index, name }))
+                tcx.mk_re_early_bound(ty::EarlyBoundRegion { def_id, index, name })
             }
 
             Some(rl::Region::Free(scope, id)) => {
                 let name = lifetime_name(id.expect_local());
-                tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                    scope,
-                    bound_region: ty::BrNamed(id, name),
-                }))
+                tcx.mk_re_free(scope, ty::BrNamed(id, name))
 
                 // (*) -- not late-bound, won't change
             }
@@ -263,7 +260,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     // elision. `resolve_lifetime` should have
                     // reported an error in this case -- but if
                     // not, let's error out.
-                    tcx.re_error_with_message(lifetime.ident.span, "unelided lifetime in signature")
+                    tcx.mk_re_error_with_message(
+                        lifetime.ident.span,
+                        "unelided lifetime in signature",
+                    )
                 })
             }
         }
@@ -477,7 +477,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             debug!(?param, "unelided lifetime in signature");
 
                             // This indicates an illegal lifetime in a non-assoc-trait position
-                            tcx.re_error_with_message(self.span, "unelided lifetime in signature")
+                            tcx.mk_re_error_with_message(
+                                self.span,
+                                "unelided lifetime in signature",
+                            )
                         })
                         .into(),
                     GenericParamDefKind::Type { has_default, .. } => {
@@ -1622,7 +1625,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         } else {
                             err.emit()
                         };
-                        tcx.re_error(e)
+                        tcx.mk_re_error(e)
                     })
                 }
             })
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 6b0eade2d32..94e1fcebccd 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -464,14 +464,10 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         if let ty::ReFree(fr) = *r {
-            self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                bound_region: self
-                    .mapping
-                    .get(&fr.bound_region)
-                    .copied()
-                    .unwrap_or(fr.bound_region),
-                ..fr
-            }))
+            self.tcx.mk_re_free(
+                fr.scope,
+                self.mapping.get(&fr.bound_region).copied().unwrap_or(fr.bound_region),
+            )
         } else {
             r
         }
@@ -777,13 +773,13 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
                     }
                     let Some(ty::ReEarlyBound(e)) = map.get(&region.into()).map(|r| r.expect_region().kind())
                     else {
-                        return tcx.re_error_with_message(return_span, "expected ReFree to map to ReEarlyBound")
+                        return tcx.mk_re_error_with_message(return_span, "expected ReFree to map to ReEarlyBound")
                     };
-                    tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
+                    tcx.mk_re_early_bound(ty::EarlyBoundRegion {
                         def_id: e.def_id,
                         name: e.name,
                         index: (e.index as usize - num_trait_substs + num_impl_substs) as u32,
-                    }))
+                    })
                 });
                 debug!(%ty);
                 collected_tys.insert(def_id, ty);
@@ -1920,10 +1916,10 @@ pub(super) fn check_type_bounds<'tcx>(
             let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
             let bound_var = ty::BoundVariableKind::Region(kind);
             bound_vars.push(bound_var);
-            tcx.mk_region(ty::ReLateBound(
+            tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind },
-            ))
+            )
             .into()
         }
         GenericParamDefKind::Const { .. } => {
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 955cacf03b1..4fc37856dfc 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -149,14 +149,14 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
     );
     let mk_va_list_ty = |mutbl| {
         tcx.lang_items().va_list().map(|did| {
-            let region = tcx.mk_region(ty::ReLateBound(
+            let region = tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0, None) },
-            ));
-            let env_region = tcx.mk_region(ty::ReLateBound(
+            );
+            let env_region = tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrEnv },
-            ));
+            );
             let va_list_ty = tcx.bound_type_of(did).subst(tcx, &[region.into()]);
             (tcx.mk_ref(env_region, ty::TypeAndMut { ty: va_list_ty, mutbl }), va_list_ty)
         })
@@ -377,9 +377,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                     ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0, None) };
                 (
                     1,
-                    vec![
-                        tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0)),
-                    ],
+                    vec![tcx.mk_imm_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), param(0))],
                     tcx.mk_projection(discriminant_def_id, tcx.mk_substs([param(0).into()].iter())),
                 )
             }
@@ -430,8 +428,7 @@ 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(0, None) };
-                let param_ty =
-                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0));
+                let param_ty = tcx.mk_imm_ref(tcx.mk_re_late_bound(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 c64d507f828..ee39fde1dcb 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -607,12 +607,11 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<'tcx>>(
                 // Same for the region. In our example, 'a corresponds
                 // to the 'me parameter.
                 let region_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_param.def_id,
-                        index: region_param.index,
-                        name: region_param.name,
-                    }));
+                let region_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_param.def_id,
+                    index: region_param.index,
+                    name: region_param.name,
+                });
                 // The predicate we expect to see. (In our example,
                 // `Self: 'me`.)
                 let clause = ty::PredicateKind::Clause(ty::Clause::TypeOutlives(
@@ -645,20 +644,18 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<'tcx>>(
                 debug!("required clause: {region_a} must outlive {region_b}");
                 // Translate into the generic parameters of the GAT.
                 let region_a_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_a_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_a_param.def_id,
-                        index: region_a_param.index,
-                        name: region_a_param.name,
-                    }));
+                let region_a_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_a_param.def_id,
+                    index: region_a_param.index,
+                    name: region_a_param.name,
+                });
                 // Same for the region.
                 let region_b_param = gat_generics.param_at(*region_b_idx, tcx);
-                let region_b_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_b_param.def_id,
-                        index: region_b_param.index,
-                        name: region_b_param.name,
-                    }));
+                let region_b_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_b_param.def_id,
+                    index: region_b_param.index,
+                    name: region_b_param.name,
+                });
                 // The predicate we expect to see.
                 let clause = ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(region_a_param, region_b_param),
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 9f33d84ab52..456c5bc99b7 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -458,13 +458,11 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
                                         self.tcx.replace_late_bound_regions_uncached(
                                             poly_trait_ref,
                                             |_| {
-                                                self.tcx.mk_region(ty::ReEarlyBound(
-                                                    ty::EarlyBoundRegion {
-                                                        def_id: item_def_id,
-                                                        index: 0,
-                                                        name: Symbol::intern(&lt_name),
-                                                    },
-                                                ))
+                                                self.tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                                                    def_id: item_def_id,
+                                                    index: 0,
+                                                    name: Symbol::intern(&lt_name),
+                                                })
                                             }
                                         ),
                                     ),
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index d0d67ae9257..5ac9003556d 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -284,11 +284,11 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
 
             let Some(dup_index) = generics.param_def_id_to_index(tcx, dup_def) else { bug!() };
 
-            let dup_region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
+            let dup_region = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
                 def_id: dup_def,
                 index: dup_index,
                 name: duplicate.name.ident().name,
-            }));
+            });
             predicates.push((
                 ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(orig_region, dup_region),