@@ -1018,7 +1018,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     expr.span,
                     hir::ExprKind::Err(self.dcx().emit_err(AwaitOnlyInAsyncFnAndBlocks {
                         await_kw_span,
-                        item_span: self.current_item,
+                        item_span: self.current_item_span,
                     })),
                 );
                 return hir::ExprKind::Block(
@@ -1712,7 +1712,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             }
             Some(hir::CoroutineKind::Coroutine(_)) => false,
             None => {
-                let suggestion = self.current_item.map(|s| s.shrink_to_lo());
+                let suggestion = self.current_item_span.map(|s| s.shrink_to_lo());
                 self.dcx().emit_err(YieldInClosure { span, suggestion });
                 self.coroutine_kind = Some(hir::CoroutineKind::Coroutine(Movability::Movable));
 
 
@@ -5,11 +5,8 @@ use rustc_errors::{E0570, ErrorGuaranteed, struct_span_code_err};
 use rustc_hir::attrs::{AttributeKind, EiiImplResolution};
 use rustc_hir::def::{DefKind, PerNS, Res};
 use rustc_hir::{
-    self as hir, CRATE_OWNER_ID, HirId, ImplItemImplKind, LifetimeSource, PredicateOrigin, Target,
-    find_attr,
+    self as hir, HirId, ImplItemImplKind, LifetimeSource, PredicateOrigin, Target, find_attr,
 };
-use rustc_middle::middle::resolve::ResolverAstLowering;
-use rustc_middle::ty::TyCtxt;
 use rustc_middle::ty::data_structures::IndexMap;
 use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::edit_distance::find_best_match_for_name;
@@ -28,14 +25,9 @@ use super::{
 };
 use crate::diagnostics::{ConstComptimeFn, ResolvingRestrictionKind, RestrictionAncestorOnly};
 
-pub(super) struct ItemLowerer<'a, 'hir> {
-    pub(super) tcx: TyCtxt<'hir>,
-    pub(super) resolver: &'a ResolverAstLowering<'hir>,
-}
-
-/// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span
-/// to the where clause that is preferred, if it exists. Otherwise, it sets the span to the other where
-/// clause if it exists.
+/// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set
+/// the span to the where clause that is preferred, if it exists. Otherwise, it sets the span to
+/// the other where clause if it exists.
 fn add_ty_alias_where_clause(
     generics: &mut ast::Generics,
     after_where_clause: &ast::WhereClause,
@@ -52,48 +44,6 @@ fn add_ty_alias_where_clause(
         if before.0 || !after.0 { before } else { after };
 }
 
-impl<'hir> ItemLowerer<'_, 'hir> {
-    fn with_lctx(
-        &mut self,
-        owner: NodeId,
-        f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
-    ) -> hir::MaybeOwner<'hir> {
-        let mut lctx = LoweringContext::new(self.tcx, self.resolver, owner);
-
-        let item = f(&mut lctx);
-
-        let info = lctx.curr_owner.into_owner_info(self.tcx, item);
-        hir::MaybeOwner::Owner(lctx.arena.alloc(info))
-    }
-
-    #[instrument(level = "debug", skip(self, c))]
-    pub(super) fn lower_crate(&mut self, c: &Crate) -> hir::MaybeOwner<'hir> {
-        self.with_lctx(CRATE_NODE_ID, |lctx| {
-            debug_assert_eq!(lctx.curr_owner.owner_id(), CRATE_OWNER_ID);
-            let module = lctx.lower_mod(&c.items, &c.spans);
-            lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, c.spans.inner_span, Target::Crate);
-            hir::OwnerNode::Crate(module)
-        })
-    }
-
-    #[instrument(level = "debug", skip(self))]
-    pub(super) fn lower_item(&mut self, item: &Item) -> hir::MaybeOwner<'hir> {
-        self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
-    }
-
-    pub(super) fn lower_trait_item(&mut self, item: &AssocItem) -> hir::MaybeOwner<'hir> {
-        self.with_lctx(item.id, |lctx| hir::OwnerNode::TraitItem(lctx.lower_trait_item(item)))
-    }
-
-    pub(super) fn lower_impl_item(&mut self, item: &AssocItem) -> hir::MaybeOwner<'hir> {
-        self.with_lctx(item.id, |lctx| hir::OwnerNode::ImplItem(lctx.lower_impl_item(item)))
-    }
-
-    pub(super) fn lower_foreign_item(&mut self, item: &ForeignItem) -> hir::MaybeOwner<'hir> {
-        self.with_lctx(item.id, |lctx| hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item)))
-    }
-}
-
 impl<'hir> LoweringContext<'_, 'hir> {
     pub(super) fn lower_mod(
         &mut self,
@@ -203,7 +153,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
+    pub(super) fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
         let owner_id = self.curr_owner.owner_id();
         let hir_id: HirId = owner_id.into();
         let vis_span = self.lower_span(i.vis.span);
@@ -544,7 +494,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             }
             ItemKind::MacroDef(ident, MacroDef { body, macro_rules, eii_declaration: _ }) => {
                 let ident = self.lower_ident(*ident);
-                let body = Box::new(self.lower_delim_args(body));
+                let body = body.clone();
                 let def_id = self.curr_owner.owner.def_id;
                 let def_kind = self.tcx.def_kind(def_id);
                 let DefKind::Macro(macro_kinds) = def_kind else {
@@ -730,7 +680,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
+    pub(super) fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
         let owner_id = self.curr_owner.owner_id();
         let hir_id: HirId = owner_id.into();
         let attrs =
@@ -911,7 +861,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
+    pub(super) fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
         let trait_item_def_id = self.curr_owner.owner_id();
         let hir_id: HirId = trait_item_def_id.into();
         let attrs = self.lower_attrs(
@@ -1160,7 +1110,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         ident
     }
 
-    fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
+    pub(super) fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
         let owner_id = self.curr_owner.owner_id();
         let hir_id: HirId = owner_id.into();
         let parent_id = self.tcx.local_parent(owner_id.def_id);
 
@@ -60,8 +60,9 @@ use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId, LocalDefIdMap};
 use rustc_hir::definitions::PerParentDisambiguatorState;
 use rustc_hir::lints::DelayedLint;
 use rustc_hir::{
-    self as hir, AngleBrackets, ConstArg, GenericArg, HirId, ItemLocalMap, LifetimeSource,
-    LifetimeSyntax, MissingLifetimeKind, ParamName, Target, TraitCandidate, find_attr,
+    self as hir, AngleBrackets, CRATE_OWNER_ID, ConstArg, GenericArg, HirId, ItemLocalMap,
+    LifetimeSource, LifetimeSyntax, MissingLifetimeKind, ParamName, Target, TraitCandidate,
+    find_attr,
 };
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_macros::extension;
@@ -296,7 +297,7 @@ struct LoweringContext<'a, 'hir> {
 
     /// Used to get the current `fn`'s def span to point to when using `await`
     /// outside of an `async fn`.
-    current_item: Option<Span>,
+    current_item_span: Option<Span>,
 
     try_block_scope: TryBlockScope,
     loop_scope: Option<HirId>,
@@ -366,7 +367,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             is_in_dyn_type: false,
             coroutine_kind: None,
             task_context: None,
-            current_item: None,
+            current_item_span: None,
 
             move_expr_bindings: Vec::new(),
             lowering_move_expr_initializer: false,
@@ -783,15 +784,37 @@ fn lower_to_hir(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::MaybeOwner<'_> {
         return fallback_to_ancestor(tcx.local_parent(def_id));
     };
 
-    let mut item_lowerer = item::ItemLowerer { tcx, resolver: &*resolver };
+    fn with_lctx<'hir>(
+        tcx: TyCtxt<'hir>,
+        resolver: &ResolverAstLowering<'hir>,
+        owner: NodeId,
+        f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
+    ) -> hir::MaybeOwner<'hir> {
+        let mut lctx = LoweringContext::new(tcx, resolver, owner);
+        let item = f(&mut lctx);
+        hir::MaybeOwner::Owner(lctx.curr_owner.into_owner_info(tcx, item))
+    }
 
     let item = match &node {
         // The item existed in the AST.
-        AstOwner::Crate(c) => item_lowerer.lower_crate(&c),
-        AstOwner::Item(item) => item_lowerer.lower_item(&item),
-        AstOwner::TraitItem(item) => item_lowerer.lower_trait_item(&item),
-        AstOwner::ImplItem(item) => item_lowerer.lower_impl_item(&item),
-        AstOwner::ForeignItem(item) => item_lowerer.lower_foreign_item(&item),
+        AstOwner::Crate(c) => with_lctx(tcx, &*resolver, CRATE_NODE_ID, |lctx| {
+            debug_assert_eq!(lctx.curr_owner.owner_id(), CRATE_OWNER_ID);
+            let module = lctx.lower_mod(&c.items, &c.spans);
+            lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, c.spans.inner_span, Target::Crate);
+            hir::OwnerNode::Crate(module)
+        }),
+        AstOwner::Item(item) => {
+            with_lctx(tcx, &*resolver, item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
+        }
+        AstOwner::TraitItem(item) => with_lctx(tcx, &*resolver, item.id, |lctx| {
+            hir::OwnerNode::TraitItem(lctx.lower_trait_item(item))
+        }),
+        AstOwner::ImplItem(item) => with_lctx(tcx, &*resolver, item.id, |lctx| {
+            hir::OwnerNode::ImplItem(lctx.lower_impl_item(item))
+        }),
+        AstOwner::ForeignItem(item) => with_lctx(tcx, &*resolver, item.id, |lctx| {
+            hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item))
+        }),
         AstOwner::NestedUseTree(owner_id) => fallback_to_ancestor(*owner_id),
         // The item existed in the AST, but is not a HIR owner.
         // Fetch the correct information from its parent.
@@ -824,7 +847,7 @@ enum GenericArgsMode {
     ParenSugar,
     /// Allow RTN, don't allow paren sugar.
     ReturnTypeNotation,
-    // Error if parenthesized generics or RTN are encountered.
+    /// Error if parenthesized generics or RTN are encountered.
     Err,
     /// Silence errors when lowering generics. Only used with `Res::Err`.
     Silence,
@@ -982,7 +1005,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     #[instrument(level = "trace", skip(self))]
-    fn lower_res(&mut self, res: Res<NodeId>) -> Res {
+    fn lower_res(&self, res: Res<NodeId>) -> Res {
         let res: Result<Res, ()> = res.apply_id(|id| {
             let owner = self.curr_owner.owner_id();
             let local_id =
@@ -999,11 +1022,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         res.unwrap_or(Res::Err)
     }
 
-    fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> {
+    fn expect_full_res(&self, id: NodeId) -> Res<NodeId> {
         self.get_partial_res(id).map_or(Res::Err, |pr| pr.expect_full_res())
     }
 
-    fn lower_import_res(&mut self, id: NodeId, span: Span) -> PerNS<Option<Res>> {
+    fn lower_import_res(&self, id: NodeId, span: Span) -> PerNS<Option<Res>> {
         debug_assert_eq!(id, self.curr_owner.owner.id);
         let per_ns = self.curr_owner.owner.import_res.map(|res| res.map(|res| self.lower_res(res)));
         if per_ns.is_empty() {
@@ -1154,8 +1177,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn with_new_scopes<T>(&mut self, scope_span: Span, f: impl FnOnce(&mut Self) -> T) -> T {
-        let current_item = self.current_item;
-        self.current_item = Some(scope_span);
+        let current_item_span = self.current_item_span;
+        self.current_item_span = Some(scope_span);
 
         let was_in_loop_condition = self.is_in_loop_condition;
         self.is_in_loop_condition = false;
@@ -1172,7 +1195,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         self.is_in_loop_condition = was_in_loop_condition;
 
-        self.current_item = current_item;
+        self.current_item_span = current_item_span;
 
         ret
     }
@@ -1261,10 +1284,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_delim_args(&self, args: &DelimArgs) -> DelimArgs {
-        args.clone()
-    }
-
     /// Lower an associated item constraint.
     #[instrument(level = "debug", skip_all)]
     fn lower_assoc_item_constraint(
@@ -1647,8 +1666,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 self.lower_array_length_to_const_arg(length),
             ),
             TyKind::TraitObject(bounds, kind) => {
-                let mut lifetime_bound = None;
                 let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
+                    let mut lifetime_bound = None;
                     let bounds =
                         this.arena.alloc_from_iter(bounds.iter().filter_map(|bound| match bound {
                             // We can safely ignore constness here since AST validation
@@ -1681,9 +1700,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                                 None
                             }
                         }));
-                    let lifetime_bound =
-                        lifetime_bound.unwrap_or_else(|| this.elided_dyn_bound(t.span));
-                    (bounds, lifetime_bound)
+                    (bounds, lifetime_bound.unwrap_or_else(|| this.elided_dyn_bound(t.span)))
                 });
                 hir::TyKind::TraitObject(bounds, TaggedRef::new(lifetime_bound, *kind))
             }
@@ -3058,15 +3075,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }))
     }
 
-    fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
+    fn lower_unsafe_source(&self, u: UnsafeSource) -> hir::UnsafeSource {
         match u {
             CompilerGenerated => hir::UnsafeSource::CompilerGenerated,
             UserProvided => hir::UnsafeSource::UserProvided,
         }
     }
 
     fn lower_trait_bound_modifiers(
-        &mut self,
+        &self,
         modifiers: TraitBoundModifiers,
     ) -> hir::TraitBoundModifiers {
         let constness = match modifiers.constness {
 
@@ -409,16 +409,6 @@ impl<'tcx, N: Idx> RegionValues<'tcx, N> {
     }
 }
 
-/// For debugging purposes, returns a pretty-printed string of the given points.
-pub(crate) fn pretty_print_points(
-    location_map: &DenseLocationMap,
-    points: impl IntoIterator<Item = PointIndex>,
-) -> String {
-    pretty_print_region_elements(
-        points.into_iter().map(|p| location_map.to_location(p)).map(RegionElement::Location),
-    )
-}
-
 /// For debugging purposes, returns a pretty-printed string of the given region elements.
 fn pretty_print_region_elements<'tcx>(
     elements: impl IntoIterator<Item = RegionElement<'tcx>>,
 
@@ -1,15 +1,18 @@
 use itertools::{Either, Itertools};
 use rustc_data_structures::fx::FxHashSet;
+use rustc_index::interval::IntervalSet;
 use rustc_middle::mir::visit::{TyContext, Visitor};
 use rustc_middle::mir::{Body, Local, Location, SourceInfo};
 use rustc_middle::ty::relate::Relate;
 use rustc_middle::ty::{GenericArgsRef, Region, RegionVid, Ty, TyCtxt, TypeVisitable};
 use rustc_mir_dataflow::move_paths::MoveData;
-use rustc_mir_dataflow::points::DenseLocationMap;
+use rustc_mir_dataflow::points::{DenseLocationMap, PointIndex};
 use rustc_span::span_bug;
+use rustc_trait_selection::traits::outlives_for_liveness::FreeRegionsVisitor;
 use tracing::debug;
 
 use super::TypeChecker;
+use crate::BorrowckInferCtxt;
 use crate::constraints::OutlivesConstraintSet;
 use crate::polonius::{PoloniusContext, record_live_region_variance};
 use crate::region_infer::values::LivenessValues;
@@ -229,3 +232,18 @@ impl<'a, 'tcx> LiveVariablesVisitor<'a, 'tcx> {
         }
     }
 }
+
+pub(crate) fn make_all_regions_live<'tcx>(
+    infcx: &BorrowckInferCtxt<'tcx>,
+    universal_regions: &UniversalRegions<'tcx>,
+    liveness: &mut LivenessValues,
+    value: impl TypeVisitable<TyCtxt<'tcx>>,
+    live_at: &IntervalSet<PointIndex>,
+) {
+    debug!("make_all_regions_live(value={value:?})");
+    value.visit_with(&mut FreeRegionsVisitor {
+        tcx: infcx.tcx,
+        param_env: infcx.param_env,
+        op: |r| liveness.add_points(universal_regions.to_region_vid(r), live_at),
+    });
+}