Merging upstream version 1.67.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

45 files changed, 1018 insertions, 797 deletions

diff --git a/compiler/rustc_borrowck/src/borrow_set.rs b/compiler/rustc_borrowck/src/borrow_set.rs
index 41279588e..5bb92a358 100644
--- a/compiler/rustc_borrowck/src/borrow_set.rs
+++ b/compiler/rustc_borrowck/src/borrow_set.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::nll::ToRegionVid;
 use crate::path_utils::allow_two_phase_borrow;
 use crate::place_ext::PlaceExt;
@@ -196,7 +198,7 @@ impl<'a, 'tcx> Visitor<'tcx> for GatherBorrows<'a, 'tcx> {
         rvalue: &mir::Rvalue<'tcx>,
         location: mir::Location,
     ) {
-        if let mir::Rvalue::Ref(region, kind, ref borrowed_place) = *rvalue {
+        if let &mir::Rvalue::Ref(region, kind, borrowed_place) = rvalue {
             if borrowed_place.ignore_borrow(self.tcx, self.body, &self.locals_state_at_exit) {
                 debug!("ignoring_borrow of {:?}", borrowed_place);
                 return;
@@ -209,7 +211,7 @@ impl<'a, 'tcx> Visitor<'tcx> for GatherBorrows<'a, 'tcx> {
                 region,
                 reserve_location: location,
                 activation_location: TwoPhaseActivation::NotTwoPhase,
-                borrowed_place: *borrowed_place,
+                borrowed_place,
                 assigned_place: *assigned_place,
             };
             let (idx, _) = self.location_map.insert_full(location, borrow);
@@ -271,14 +273,14 @@ impl<'a, 'tcx> Visitor<'tcx> for GatherBorrows<'a, 'tcx> {
     }
 
     fn visit_rvalue(&mut self, rvalue: &mir::Rvalue<'tcx>, location: mir::Location) {
-        if let mir::Rvalue::Ref(region, kind, ref place) = *rvalue {
+        if let &mir::Rvalue::Ref(region, kind, place) = rvalue {
             // double-check that we already registered a BorrowData for this
 
             let borrow_data = &self.location_map[&location];
             assert_eq!(borrow_data.reserve_location, location);
             assert_eq!(borrow_data.kind, kind);
             assert_eq!(borrow_data.region, region.to_region_vid());
-            assert_eq!(borrow_data.borrowed_place, *place);
+            assert_eq!(borrow_data.borrowed_place, place);
         }
 
         self.super_rvalue(rvalue, location)
diff --git a/compiler/rustc_borrowck/src/borrowck_errors.rs b/compiler/rustc_borrowck/src/borrowck_errors.rs
index 08ea00d71..01be37912 100644
--- a/compiler/rustc_borrowck/src/borrowck_errors.rs
+++ b/compiler/rustc_borrowck/src/borrowck_errors.rs
@@ -8,9 +8,18 @@ impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
     pub(crate) fn cannot_move_when_borrowed(
         &self,
         span: Span,
-        desc: &str,
+        borrow_span: Span,
+        place: &str,
+        borrow_place: &str,
+        value_place: &str,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
-        struct_span_err!(self, span, E0505, "cannot move out of {} because it is borrowed", desc,)
+        self.infcx.tcx.sess.create_err(crate::session_diagnostics::MoveBorrow {
+            place,
+            span,
+            borrow_place,
+            value_place,
+            borrow_span,
+        })
     }
 
     pub(crate) fn cannot_use_when_mutably_borrowed(
diff --git a/compiler/rustc_borrowck/src/constraint_generation.rs b/compiler/rustc_borrowck/src/constraint_generation.rs
index f185e402f..11b31c3f1 100644
--- a/compiler/rustc_borrowck/src/constraint_generation.rs
+++ b/compiler/rustc_borrowck/src/constraint_generation.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_infer::infer::InferCtxt;
 use rustc_middle::mir::visit::TyContext;
 use rustc_middle::mir::visit::Visitor;
diff --git a/compiler/rustc_borrowck/src/constraints/graph.rs b/compiler/rustc_borrowck/src/constraints/graph.rs
index 609fbc2bc..385f15317 100644
--- a/compiler/rustc_borrowck/src/constraints/graph.rs
+++ b/compiler/rustc_borrowck/src/constraints/graph.rs
@@ -163,6 +163,7 @@ impl<'s, 'tcx, D: ConstraintGraphDirecton> Iterator for Edges<'s, 'tcx, D> {
                 span: DUMMY_SP,
                 category: ConstraintCategory::Internal,
                 variance_info: VarianceDiagInfo::default(),
+                from_closure: false,
             })
         } else {
             None
diff --git a/compiler/rustc_borrowck/src/constraints/mod.rs b/compiler/rustc_borrowck/src/constraints/mod.rs
index df0412813..84a93e5f7 100644
--- a/compiler/rustc_borrowck/src/constraints/mod.rs
+++ b/compiler/rustc_borrowck/src/constraints/mod.rs
@@ -1,3 +1,6 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
+
 use rustc_data_structures::graph::scc::Sccs;
 use rustc_index::vec::IndexVec;
 use rustc_middle::mir::ConstraintCategory;
@@ -96,6 +99,9 @@ pub struct OutlivesConstraint<'tcx> {
 
     /// Variance diagnostic information
     pub variance_info: VarianceDiagInfo<'tcx>,
+
+    /// If this constraint is promoted from closure requirements.
+    pub from_closure: bool,
 }
 
 impl<'tcx> fmt::Debug for OutlivesConstraint<'tcx> {
diff --git a/compiler/rustc_borrowck/src/consumers.rs b/compiler/rustc_borrowck/src/consumers.rs
index b162095f8..86da767f3 100644
--- a/compiler/rustc_borrowck/src/consumers.rs
+++ b/compiler/rustc_borrowck/src/consumers.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! This file provides API for compiler consumers.
 
 use rustc_hir::def_id::LocalDefId;
diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 9f7a4d499..f825b1d8f 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::mir::{self, BasicBlock, Body, Location, Place};
@@ -356,9 +358,9 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
         stmt: &mir::Statement<'tcx>,
         location: Location,
     ) {
-        match stmt.kind {
-            mir::StatementKind::Assign(box (lhs, ref rhs)) => {
-                if let mir::Rvalue::Ref(_, _, place) = *rhs {
+        match &stmt.kind {
+            mir::StatementKind::Assign(box (lhs, rhs)) => {
+                if let mir::Rvalue::Ref(_, _, place) = rhs {
                     if place.ignore_borrow(
                         self.tcx,
                         self.body,
@@ -375,13 +377,13 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
 
                 // Make sure there are no remaining borrows for variables
                 // that are assigned over.
-                self.kill_borrows_on_place(trans, lhs);
+                self.kill_borrows_on_place(trans, *lhs);
             }
 
             mir::StatementKind::StorageDead(local) => {
                 // Make sure there are no remaining borrows for locals that
                 // are gone out of scope.
-                self.kill_borrows_on_place(trans, Place::from(local));
+                self.kill_borrows_on_place(trans, Place::from(*local));
             }
 
             mir::StatementKind::FakeRead(..)
diff --git a/compiler/rustc_borrowck/src/def_use.rs b/compiler/rustc_borrowck/src/def_use.rs
index a5c0d7742..8e62a0198 100644
--- a/compiler/rustc_borrowck/src/def_use.rs
+++ b/compiler/rustc_borrowck/src/def_use.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_middle::mir::visit::{
     MutatingUseContext, NonMutatingUseContext, NonUseContext, PlaceContext,
 };
diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index 02071ed6b..1550958ab 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -1,3 +1,6 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
+
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
 use rustc_infer::infer::canonical::Canonical;
 use rustc_infer::infer::error_reporting::nice_region_error::NiceRegionError;
@@ -5,14 +8,14 @@ use rustc_infer::infer::region_constraints::Constraint;
 use rustc_infer::infer::region_constraints::RegionConstraintData;
 use rustc_infer::infer::RegionVariableOrigin;
 use rustc_infer::infer::{InferCtxt, RegionResolutionError, SubregionOrigin, TyCtxtInferExt as _};
-use rustc_infer::traits::{Normalized, ObligationCause, TraitEngine, TraitEngineExt};
+use rustc_infer::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::RegionVid;
 use rustc_middle::ty::UniverseIndex;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 use rustc_trait_selection::traits::query::type_op;
-use rustc_trait_selection::traits::{SelectionContext, TraitEngineExt as _};
+use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_traits::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_cause};
 
 use std::fmt;
@@ -158,6 +161,7 @@ trait TypeOpInfo<'tcx> {
         error_region: Option<ty::Region<'tcx>>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>>;
 
+    #[instrument(level = "debug", skip(self, mbcx))]
     fn report_error(
         &self,
         mbcx: &mut MirBorrowckCtxt<'_, 'tcx>,
@@ -167,6 +171,7 @@ trait TypeOpInfo<'tcx> {
     ) {
         let tcx = mbcx.infcx.tcx;
         let base_universe = self.base_universe();
+        debug!(?base_universe);
 
         let Some(adjusted_universe) =
             placeholder.universe.as_u32().checked_sub(base_universe.as_u32())
@@ -238,11 +243,11 @@ impl<'tcx> TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
-        let (ref infcx, key, _) =
+        let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
-        let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
-        type_op_prove_predicate_with_cause(infcx, &mut *fulfill_cx, key, cause);
-        try_extract_error_from_fulfill_cx(fulfill_cx, infcx, placeholder_region, error_region)
+        let ocx = ObligationCtxt::new(&infcx);
+        type_op_prove_predicate_with_cause(&ocx, key, cause);
+        try_extract_error_from_fulfill_cx(&ocx, placeholder_region, error_region)
     }
 }
 
@@ -279,24 +284,20 @@ where
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
-        let (ref infcx, key, _) =
+        let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
-        let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
-
-        let mut selcx = SelectionContext::new(infcx);
+        let ocx = ObligationCtxt::new(&infcx);
 
         // FIXME(lqd): Unify and de-duplicate the following with the actual
         // `rustc_traits::type_op::type_op_normalize` query to allow the span we need in the
         // `ObligationCause`. The normalization results are currently different between
-        // `AtExt::normalize` used in the query and `normalize` called below: the former fails
-        // to normalize the `nll/relate_tys/impl-fn-ignore-binder-via-bottom.rs` test. Check
-        // after #85499 lands to see if its fixes have erased this difference.
+        // `QueryNormalizeExt::query_normalize` used in the query and `normalize` called below:
+        // the former fails to normalize the `nll/relate_tys/impl-fn-ignore-binder-via-bottom.rs` test.
+        // Check after #85499 lands to see if its fixes have erased this difference.
         let (param_env, value) = key.into_parts();
-        let Normalized { value: _, obligations } =
-            rustc_trait_selection::traits::normalize(&mut selcx, param_env, cause, value.value);
-        fulfill_cx.register_predicate_obligations(infcx, obligations);
+        let _ = ocx.normalize(&cause, param_env, value.value);
 
-        try_extract_error_from_fulfill_cx(fulfill_cx, infcx, placeholder_region, error_region)
+        try_extract_error_from_fulfill_cx(&ocx, placeholder_region, error_region)
     }
 }
 
@@ -327,11 +328,11 @@ impl<'tcx> TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> {
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
-        let (ref infcx, key, _) =
+        let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
-        let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
-        type_op_ascribe_user_type_with_span(infcx, &mut *fulfill_cx, key, Some(cause.span)).ok()?;
-        try_extract_error_from_fulfill_cx(fulfill_cx, infcx, placeholder_region, error_region)
+        let ocx = ObligationCtxt::new(&infcx);
+        type_op_ascribe_user_type_with_span(&ocx, key, Some(cause.span)).ok()?;
+        try_extract_error_from_fulfill_cx(&ocx, placeholder_region, error_region)
     }
 }
 
@@ -372,28 +373,28 @@ impl<'tcx> TypeOpInfo<'tcx> for crate::type_check::InstantiateOpaqueType<'tcx> {
     }
 }
 
-#[instrument(skip(fulfill_cx, infcx), level = "debug")]
+#[instrument(skip(ocx), level = "debug")]
 fn try_extract_error_from_fulfill_cx<'tcx>(
-    mut fulfill_cx: Box<dyn TraitEngine<'tcx> + 'tcx>,
-    infcx: &InferCtxt<'tcx>,
+    ocx: &ObligationCtxt<'_, 'tcx>,
     placeholder_region: ty::Region<'tcx>,
     error_region: Option<ty::Region<'tcx>>,
 ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
     // We generally shouldn't have errors here because the query was
     // already run, but there's no point using `delay_span_bug`
     // when we're going to emit an error here anyway.
-    let _errors = fulfill_cx.select_all_or_error(infcx);
-    let region_constraints = infcx.with_region_constraints(|r| r.clone());
+    let _errors = ocx.select_all_or_error();
+    let region_constraints = ocx.infcx.with_region_constraints(|r| r.clone());
     try_extract_error_from_region_constraints(
-        infcx,
+        ocx.infcx,
         placeholder_region,
         error_region,
         &region_constraints,
-        |vid| infcx.region_var_origin(vid),
-        |vid| infcx.universe_of_region(infcx.tcx.mk_region(ty::ReVar(vid))),
+        |vid| ocx.infcx.region_var_origin(vid),
+        |vid| ocx.infcx.universe_of_region(ocx.infcx.tcx.mk_region(ty::ReVar(vid))),
     )
 }
 
+#[instrument(level = "debug", skip(infcx, region_var_origin, universe_of_region))]
 fn try_extract_error_from_region_constraints<'tcx>(
     infcx: &InferCtxt<'tcx>,
     placeholder_region: ty::Region<'tcx>,
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 583bc2e28..5e3745f17 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -7,7 +7,7 @@ use rustc_errors::{
 };
 use rustc_hir as hir;
 use rustc_hir::intravisit::{walk_block, walk_expr, Visitor};
-use rustc_hir::{AsyncGeneratorKind, GeneratorKind};
+use rustc_hir::{AsyncGeneratorKind, GeneratorKind, LangItem};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::mir::tcx::PlaceTy;
@@ -23,7 +23,6 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, Span, Symbol};
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::TraitEngineExt as _;
 
 use crate::borrow_set::TwoPhaseActivation;
 use crate::borrowck_errors;
@@ -168,10 +167,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 );
             }
 
-            self.add_moved_or_invoked_closure_note(location, used_place, &mut err);
+            let closure = self.add_moved_or_invoked_closure_note(location, used_place, &mut err);
 
             let mut is_loop_move = false;
             let mut in_pattern = false;
+            let mut seen_spans = FxHashSet::default();
 
             for move_site in &move_site_vec {
                 let move_out = self.move_data.moves[(*move_site).moi];
@@ -192,43 +192,28 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     is_loop_move = true;
                 }
 
-                self.explain_captures(
-                    &mut err,
-                    span,
-                    move_span,
-                    move_spans,
-                    *moved_place,
-                    partially_str,
-                    loop_message,
-                    move_msg,
-                    is_loop_move,
-                    maybe_reinitialized_locations.is_empty(),
-                );
-
-                if let (UseSpans::PatUse(span), []) =
-                    (move_spans, &maybe_reinitialized_locations[..])
-                {
-                    if maybe_reinitialized_locations.is_empty() {
-                        err.span_suggestion_verbose(
-                            span.shrink_to_lo(),
-                            &format!(
-                                "borrow this field in the pattern to avoid moving {}",
-                                self.describe_place(moved_place.as_ref())
-                                    .map(|n| format!("`{}`", n))
-                                    .unwrap_or_else(|| "the value".to_string())
-                            ),
-                            "ref ",
-                            Applicability::MachineApplicable,
-                        );
-                        in_pattern = true;
+                if !seen_spans.contains(&move_span) {
+                    if !closure {
+                        self.suggest_ref_or_clone(mpi, move_span, &mut err, &mut in_pattern);
                     }
+
+                    self.explain_captures(
+                        &mut err,
+                        span,
+                        move_span,
+                        move_spans,
+                        *moved_place,
+                        partially_str,
+                        loop_message,
+                        move_msg,
+                        is_loop_move,
+                        maybe_reinitialized_locations.is_empty(),
+                    );
                 }
+                seen_spans.insert(move_span);
             }
 
-            use_spans.var_span_label_path_only(
-                &mut err,
-                format!("{} occurs due to use{}", desired_action.as_noun(), use_spans.describe()),
-            );
+            use_spans.var_path_only_subdiag(&mut err, desired_action);
 
             if !is_loop_move {
                 err.span_label(
@@ -280,7 +265,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 DescribePlaceOpt { including_downcast: true, including_tuple_field: true },
             );
             let note_msg = match opt_name {
-                Some(ref name) => format!("`{}`", name),
+                Some(name) => format!("`{}`", name),
                 None => "value".to_owned(),
             };
             if self.suggest_borrow_fn_like(&mut err, ty, &move_site_vec, &note_msg) {
@@ -321,6 +306,160 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
     }
 
+    fn suggest_ref_or_clone(
+        &mut self,
+        mpi: MovePathIndex,
+        move_span: Span,
+        err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
+        in_pattern: &mut bool,
+    ) {
+        struct ExpressionFinder<'hir> {
+            expr_span: Span,
+            expr: Option<&'hir hir::Expr<'hir>>,
+            pat: Option<&'hir hir::Pat<'hir>>,
+            parent_pat: Option<&'hir hir::Pat<'hir>>,
+        }
+        impl<'hir> Visitor<'hir> for ExpressionFinder<'hir> {
+            fn visit_expr(&mut self, e: &'hir hir::Expr<'hir>) {
+                if e.span == self.expr_span {
+                    self.expr = Some(e);
+                }
+                hir::intravisit::walk_expr(self, e);
+            }
+            fn visit_pat(&mut self, p: &'hir hir::Pat<'hir>) {
+                if p.span == self.expr_span {
+                    self.pat = Some(p);
+                }
+                if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, _, i, sub) = p.kind {
+                    if i.span == self.expr_span || p.span == self.expr_span {
+                        self.pat = Some(p);
+                    }
+                    // Check if we are in a situation of `ident @ ident` where we want to suggest
+                    // `ref ident @ ref ident` or `ref ident @ Struct { ref ident }`.
+                    if let Some(subpat) = sub && self.pat.is_none() {
+                        self.visit_pat(subpat);
+                        if self.pat.is_some() {
+                            self.parent_pat = Some(p);
+                        }
+                        return;
+                    }
+                }
+                hir::intravisit::walk_pat(self, p);
+            }
+        }
+        let hir = self.infcx.tcx.hir();
+        if let Some(hir::Node::Item(hir::Item {
+            kind: hir::ItemKind::Fn(_, _, body_id),
+            ..
+        })) = hir.find(hir.local_def_id_to_hir_id(self.mir_def_id()))
+            && let Some(hir::Node::Expr(expr)) = hir.find(body_id.hir_id)
+        {
+            let place = &self.move_data.move_paths[mpi].place;
+            let span = place.as_local()
+                .map(|local| self.body.local_decls[local].source_info.span);
+            let mut finder = ExpressionFinder {
+                expr_span: move_span,
+                expr: None,
+                pat: None,
+                parent_pat: None,
+            };
+            finder.visit_expr(expr);
+            if let Some(span) = span && let Some(expr) = finder.expr {
+                for (_, expr) in hir.parent_iter(expr.hir_id) {
+                    if let hir::Node::Expr(expr) = expr {
+                        if expr.span.contains(span) {
+                            // If the let binding occurs within the same loop, then that
+                            // loop isn't relevant, like in the following, the outermost `loop`
+                            // doesn't play into `x` being moved.
+                            // ```
+                            // loop {
+                            //     let x = String::new();
+                            //     loop {
+                            //         foo(x);
+                            //     }
+                            // }
+                            // ```
+                            break;
+                        }
+                        if let hir::ExprKind::Loop(.., loop_span) = expr.kind {
+                            err.span_label(loop_span, "inside of this loop");
+                        }
+                    }
+                }
+                let typeck = self.infcx.tcx.typeck(self.mir_def_id());
+                let hir_id = hir.get_parent_node(expr.hir_id);
+                if let Some(parent) = hir.find(hir_id) {
+                    let (def_id, args, offset) = if let hir::Node::Expr(parent_expr) = parent
+                        && let hir::ExprKind::MethodCall(_, _, args, _) = parent_expr.kind
+                        && let Some(def_id) = typeck.type_dependent_def_id(parent_expr.hir_id)
+                    {
+                        (def_id.as_local(), args, 1)
+                    } else if let hir::Node::Expr(parent_expr) = parent
+                        && let hir::ExprKind::Call(call, args) = parent_expr.kind
+                        && let ty::FnDef(def_id, _) = typeck.node_type(call.hir_id).kind()
+                    {
+                        (def_id.as_local(), args, 0)
+                    } else {
+                        (None, &[][..], 0)
+                    };
+                    if let Some(def_id) = def_id
+                        && let Some(node) = hir.find(hir.local_def_id_to_hir_id(def_id))
+                        && let Some(fn_sig) = node.fn_sig()
+                        && let Some(ident) = node.ident()
+                        && let Some(pos) = args.iter().position(|arg| arg.hir_id == expr.hir_id)
+                        && let Some(arg) = fn_sig.decl.inputs.get(pos + offset)
+                    {
+                        let mut span: MultiSpan = arg.span.into();
+                        span.push_span_label(
+                            arg.span,
+                            "this parameter takes ownership of the value".to_string(),
+                        );
+                        let descr = match node.fn_kind() {
+                            Some(hir::intravisit::FnKind::ItemFn(..)) | None => "function",
+                            Some(hir::intravisit::FnKind::Method(..)) => "method",
+                            Some(hir::intravisit::FnKind::Closure) => "closure",
+                        };
+                        span.push_span_label(
+                            ident.span,
+                            format!("in this {descr}"),
+                        );
+                        err.span_note(
+                            span,
+                            format!(
+                                "consider changing this parameter type in {descr} `{ident}` to \
+                                 borrow instead if owning the value isn't necessary",
+                            ),
+                        );
+                    }
+                    let place = &self.move_data.move_paths[mpi].place;
+                    let ty = place.ty(self.body, self.infcx.tcx).ty;
+                    if let hir::Node::Expr(parent_expr) = parent
+                        && let hir::ExprKind::Call(call_expr, _) = parent_expr.kind
+                        && let hir::ExprKind::Path(
+                            hir::QPath::LangItem(LangItem::IntoIterIntoIter, _, _)
+                        ) = call_expr.kind
+                    {
+                        // Do not suggest `.clone()` in a `for` loop, we already suggest borrowing.
+                    } else {
+                        self.suggest_cloning(err, ty, move_span);
+                    }
+                }
+            }
+            if let Some(pat) = finder.pat {
+                *in_pattern = true;
+                let mut sugg = vec![(pat.span.shrink_to_lo(), "ref ".to_string())];
+                if let Some(pat) = finder.parent_pat {
+                    sugg.insert(0, (pat.span.shrink_to_lo(), "ref ".to_string()));
+                }
+                err.multipart_suggestion_verbose(
+                    "borrow this binding in the pattern to avoid moving the value",
+                    sugg,
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+    }
+
     fn report_use_of_uninitialized(
         &self,
         mpi: MovePathIndex,
@@ -405,10 +544,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let used = desired_action.as_general_verb_in_past_tense();
         let mut err =
             struct_span_err!(self, span, E0381, "{used} binding {desc}{isnt_initialized}");
-        use_spans.var_span_label_path_only(
-            &mut err,
-            format!("{} occurs due to use{}", desired_action.as_noun(), use_spans.describe()),
-        );
+        use_spans.var_path_only_subdiag(&mut err, desired_action);
 
         if let InitializationRequiringAction::PartialAssignment
         | InitializationRequiringAction::Assignment = desired_action
@@ -496,12 +632,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             // but the type has region variables, so erase those.
             tcx.infer_ctxt()
                 .build()
-                .type_implements_trait(
-                    default_trait,
-                    tcx.erase_regions(ty),
-                    ty::List::empty(),
-                    param_env,
-                )
+                .type_implements_trait(default_trait, [tcx.erase_regions(ty)], param_env)
                 .must_apply_modulo_regions()
         };
 
@@ -535,15 +666,17 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let tcx = self.infcx.tcx;
 
         // Find out if the predicates show that the type is a Fn or FnMut
-        let find_fn_kind_from_did =
-            |predicates: ty::EarlyBinder<&[(ty::Predicate<'tcx>, Span)]>, substs| {
-                predicates.0.iter().find_map(|(pred, _)| {
+        let find_fn_kind_from_did = |predicates: ty::EarlyBinder<
+            &[(ty::Predicate<'tcx>, Span)],
+        >,
+                                     substs| {
+            predicates.0.iter().find_map(|(pred, _)| {
                     let pred = if let Some(substs) = substs {
                         predicates.rebind(*pred).subst(tcx, substs).kind().skip_binder()
                     } else {
                         pred.kind().skip_binder()
                     };
-                    if let ty::PredicateKind::Trait(pred) = pred && pred.self_ty() == ty {
+                    if let ty::PredicateKind::Clause(ty::Clause::Trait(pred)) = pred && pred.self_ty() == ty {
                     if Some(pred.def_id()) == tcx.lang_items().fn_trait() {
                         return Some(hir::Mutability::Not);
                     } else if Some(pred.def_id()) == tcx.lang_items().fn_mut_trait() {
@@ -552,7 +685,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 }
                     None
                 })
-            };
+        };
 
         // If the type is opaque/param/closure, and it is Fn or FnMut, let's suggest (mutably)
         // borrowing the type, since `&mut F: FnMut` iff `F: FnMut` and similarly for `Fn`.
@@ -583,25 +716,41 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 let moved_place = &self.move_data.move_paths[move_out.path].place;
                 let move_spans = self.move_spans(moved_place.as_ref(), move_out.source);
                 let move_span = move_spans.args_or_use();
-                let suggestion = if borrow_level == hir::Mutability::Mut {
-                    "&mut ".to_string()
-                } else {
-                    "&".to_string()
-                };
+                let suggestion = borrow_level.ref_prefix_str().to_owned();
                 (move_span.shrink_to_lo(), suggestion)
             })
             .collect();
         err.multipart_suggestion_verbose(
-            &format!(
-                "consider {}borrowing {value_name}",
-                if borrow_level == hir::Mutability::Mut { "mutably " } else { "" }
-            ),
+            format!("consider {}borrowing {value_name}", borrow_level.mutably_str()),
             sugg,
             Applicability::MaybeIncorrect,
         );
         true
     }
 
+    fn suggest_cloning(&self, err: &mut Diagnostic, ty: Ty<'tcx>, span: Span) {
+        let tcx = self.infcx.tcx;
+        // Try to find predicates on *generic params* that would allow copying `ty`
+        let infcx = tcx.infer_ctxt().build();
+
+        if let Some(clone_trait_def) = tcx.lang_items().clone_trait()
+            && infcx
+                .type_implements_trait(
+                    clone_trait_def,
+                    [tcx.erase_regions(ty)],
+                    self.param_env,
+                )
+                .must_apply_modulo_regions()
+        {
+            err.span_suggestion_verbose(
+                span.shrink_to_hi(),
+                "consider cloning the value if the performance cost is acceptable",
+                ".clone()".to_string(),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
     fn suggest_adding_copy_bounds(&self, err: &mut Diagnostic, ty: Ty<'tcx>, span: Span) {
         let tcx = self.infcx.tcx;
         let generics = tcx.generics_of(self.mir_def_id());
@@ -613,36 +762,34 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         else { return; };
         // Try to find predicates on *generic params* that would allow copying `ty`
         let infcx = tcx.infer_ctxt().build();
-        let mut fulfill_cx = <dyn rustc_infer::traits::TraitEngine<'_>>::new(infcx.tcx);
-
-        let copy_did = infcx.tcx.lang_items().copy_trait().unwrap();
+        let copy_did = infcx.tcx.require_lang_item(LangItem::Copy, Some(span));
         let cause = ObligationCause::new(
             span,
             self.mir_hir_id(),
             rustc_infer::traits::ObligationCauseCode::MiscObligation,
         );
-        fulfill_cx.register_bound(
+        let errors = rustc_trait_selection::traits::fully_solve_bound(
             &infcx,
+            cause,
             self.param_env,
             // Erase any region vids from the type, which may not be resolved
             infcx.tcx.erase_regions(ty),
             copy_did,
-            cause,
         );
-        // Select all, including ambiguous predicates
-        let errors = fulfill_cx.select_all_or_error(&infcx);
 
         // Only emit suggestion if all required predicates are on generic
         let predicates: Result<Vec<_>, _> = errors
             .into_iter()
             .map(|err| match err.obligation.predicate.kind().skip_binder() {
-                PredicateKind::Trait(predicate) => match predicate.self_ty().kind() {
-                    ty::Param(param_ty) => Ok((
-                        generics.type_param(param_ty, tcx),
-                        predicate.trait_ref.print_only_trait_path().to_string(),
-                    )),
-                    _ => Err(()),
-                },
+                PredicateKind::Clause(ty::Clause::Trait(predicate)) => {
+                    match predicate.self_ty().kind() {
+                        ty::Param(param_ty) => Ok((
+                            generics.type_param(param_ty, tcx),
+                            predicate.trait_ref.print_only_trait_path().to_string(),
+                        )),
+                        _ => Err(()),
+                    }
+                }
                 _ => Err(()),
             })
             .collect();
@@ -678,16 +825,16 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let move_spans = self.move_spans(place.as_ref(), location);
         let span = move_spans.args_or_use();
 
-        let mut err =
-            self.cannot_move_when_borrowed(span, &self.describe_any_place(place.as_ref()));
-        err.span_label(borrow_span, format!("borrow of {} occurs here", borrow_msg));
-        err.span_label(span, format!("move out of {} occurs here", value_msg));
-
-        borrow_spans.var_span_label_path_only(
-            &mut err,
-            format!("borrow occurs due to use{}", borrow_spans.describe()),
+        let mut err = self.cannot_move_when_borrowed(
+            span,
+            borrow_span,
+            &self.describe_any_place(place.as_ref()),
+            &borrow_msg,
+            &value_msg,
         );
 
+        borrow_spans.var_path_only_subdiag(&mut err, crate::InitializationRequiringAction::Borrow);
+
         move_spans.var_span_label(
             &mut err,
             format!("move occurs due to use{}", move_spans.describe()),
@@ -729,16 +876,15 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             borrow_span,
             &self.describe_any_place(borrow.borrowed_place.as_ref()),
         );
-
-        borrow_spans.var_span_label(
-            &mut err,
-            {
-                let place = &borrow.borrowed_place;
-                let desc_place = self.describe_any_place(place.as_ref());
-                format!("borrow occurs due to use of {}{}", desc_place, borrow_spans.describe())
-            },
-            "mutable",
-        );
+        borrow_spans.var_subdiag(&mut err, Some(borrow.kind), |kind, var_span| {
+            use crate::session_diagnostics::CaptureVarCause::*;
+            let place = &borrow.borrowed_place;
+            let desc_place = self.describe_any_place(place.as_ref());
+            match kind {
+                Some(_) => BorrowUsePlaceGenerator { place: desc_place, var_span },
+                None => BorrowUsePlaceClosure { place: desc_place, var_span },
+            }
+        });
 
         self.explain_why_borrow_contains_point(location, borrow, None)
             .add_explanation_to_diagnostic(
@@ -1271,7 +1417,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             // then just use the normal error. The closure isn't escaping
             // and `move` will not help here.
             (
-                Some(ref name),
+                Some(name),
                 BorrowExplanation::MustBeValidFor {
                     category:
                         category @ (ConstraintCategory::Return(_)
@@ -1292,7 +1438,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     &format!("`{}`", name),
                 ),
             (
-                ref name,
+                name,
                 BorrowExplanation::MustBeValidFor {
                     category: ConstraintCategory::Assignment,
                     from_closure: false,
@@ -1304,7 +1450,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     span,
                     ..
                 },
-            ) => self.report_escaping_data(borrow_span, name, upvar_span, upvar_name, span),
+            ) => self.report_escaping_data(borrow_span, &name, upvar_span, upvar_name, span),
             (Some(name), explanation) => self.report_local_value_does_not_live_long_enough(
                 location,
                 &name,
@@ -1556,7 +1702,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
 
         let mut err = self.temporary_value_borrowed_for_too_long(proper_span);
-        err.span_label(proper_span, "creates a temporary which is freed while still in use");
+        err.span_label(proper_span, "creates a temporary value which is freed while still in use");
         err.span_label(drop_span, "temporary value is freed at the end of this statement");
 
         match explanation {
@@ -1719,7 +1865,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             err.span_label(borrow_span, note);
 
             let tcx = self.infcx.tcx;
-            let ty_params = ty::List::empty();
 
             let return_ty = self.regioncx.universal_regions().unnormalized_output_ty;
             let return_ty = tcx.erase_regions(return_ty);
@@ -1728,7 +1873,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             if let Some(iter_trait) = tcx.get_diagnostic_item(sym::Iterator)
                 && self
                     .infcx
-                    .type_implements_trait(iter_trait, return_ty, ty_params, self.param_env)
+                    .type_implements_trait(iter_trait, [return_ty], self.param_env)
                     .must_apply_modulo_regions()
             {
                 err.span_suggestion_hidden(
@@ -2307,7 +2452,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         // and it'll make sense.
         let location = borrow.reserve_location;
         debug!("annotate_argument_and_return_for_borrow: location={:?}", location);
-        if let Some(&Statement { kind: StatementKind::Assign(box (ref reservation, _)), .. }) =
+        if let Some(Statement { kind: StatementKind::Assign(box (reservation, _)), .. }) =
             &self.body[location.block].statements.get(location.statement_index)
         {
             debug!("annotate_argument_and_return_for_borrow: reservation={:?}", reservation);
@@ -2335,8 +2480,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         // Check if our `target` was captured by a closure.
                         if let Rvalue::Aggregate(
                             box AggregateKind::Closure(def_id, substs),
-                            ref operands,
-                        ) = *rvalue
+                            operands,
+                        ) = rvalue
                         {
                             for operand in operands {
                                 let (Operand::Copy(assigned_from) | Operand::Move(assigned_from)) = operand else {
@@ -2360,7 +2505,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                 // into a place then we should annotate the closure in
                                 // case it ends up being assigned into the return place.
                                 annotated_closure =
-                                    self.annotate_fn_sig(def_id, substs.as_closure().sig());
+                                    self.annotate_fn_sig(*def_id, substs.as_closure().sig());
                                 debug!(
                                     "annotate_argument_and_return_for_borrow: \
                                      annotated_closure={:?} assigned_from_local={:?} \
@@ -2527,7 +2672,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             if let hir::TyKind::Rptr(lifetime, _) = &fn_decl.inputs[index].kind {
                                 // With access to the lifetime, we can get
                                 // the span of it.
-                                arguments.push((*argument, lifetime.span));
+                                arguments.push((*argument, lifetime.ident.span));
                             } else {
                                 bug!("ty type is a ref but hir type is not");
                             }
@@ -2546,7 +2691,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 let mut return_span = fn_decl.output.span();
                 if let hir::FnRetTy::Return(ty) = &fn_decl.output {
                     if let hir::TyKind::Rptr(lifetime, _) = ty.kind {
-                        return_span = lifetime.span;
+                        return_span = lifetime.ident.span;
                     }
                 }
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index 582d683dd..304683618 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -469,8 +469,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 } else if self.was_captured_by_trait_object(borrow) {
                     LaterUseKind::TraitCapture
                 } else if location.statement_index == block.statements.len() {
-                    if let TerminatorKind::Call { ref func, from_hir_call: true, .. } =
-                        block.terminator().kind
+                    if let TerminatorKind::Call { func, from_hir_call: true, .. } =
+                        &block.terminator().kind
                     {
                         // Just point to the function, to reduce the chance of overlapping spans.
                         let function_span = match func {
@@ -515,19 +515,16 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         // will only ever have one item at any given time, but by using a vector, we can pop from
         // it which simplifies the termination logic.
         let mut queue = vec![location];
-        let mut target = if let Some(&Statement {
-            kind: StatementKind::Assign(box (ref place, _)),
-            ..
-        }) = stmt
-        {
-            if let Some(local) = place.as_local() {
-                local
+        let mut target =
+            if let Some(Statement { kind: StatementKind::Assign(box (place, _)), .. }) = stmt {
+                if let Some(local) = place.as_local() {
+                    local
+                } else {
+                    return false;
+                }
             } else {
                 return false;
-            }
-        } else {
-            return false;
-        };
+            };
 
         debug!("was_captured_by_trait: target={:?} queue={:?}", target, queue);
         while let Some(current_location) = queue.pop() {
diff --git a/compiler/rustc_borrowck/src/diagnostics/find_all_local_uses.rs b/compiler/rustc_borrowck/src/diagnostics/find_all_local_uses.rs
index b3edc35dc..498e98343 100644
--- a/compiler/rustc_borrowck/src/diagnostics/find_all_local_uses.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/find_all_local_uses.rs
@@ -1,3 +1,6 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
+
 use std::collections::BTreeSet;
 
 use rustc_middle::mir::visit::{PlaceContext, Visitor};
diff --git a/compiler/rustc_borrowck/src/diagnostics/find_use.rs b/compiler/rustc_borrowck/src/diagnostics/find_use.rs
index b5a3081e5..15f42e26c 100644
--- a/compiler/rustc_borrowck/src/diagnostics/find_use.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/find_use.rs
@@ -1,3 +1,6 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
+
 use std::collections::VecDeque;
 use std::rc::Rc;
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index 534d9ecae..4e2271a30 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -70,7 +70,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         location: Location,
         place: PlaceRef<'tcx>,
         diag: &mut Diagnostic,
-    ) {
+    ) -> bool {
         debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
         let mut target = place.local_or_deref_local();
         for stmt in &self.body[location.block].statements[location.statement_index..] {
@@ -78,7 +78,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             if let StatementKind::Assign(box (into, Rvalue::Use(from))) = &stmt.kind {
                 debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
                 match from {
-                    Operand::Copy(ref place) | Operand::Move(ref place)
+                    Operand::Copy(place) | Operand::Move(place)
                         if target == place.local_or_deref_local() =>
                     {
                         target = into.local_or_deref_local()
@@ -101,12 +101,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 debug!("add_moved_or_invoked_closure_note: id={:?}", id);
                 if Some(self.infcx.tcx.parent(id)) == self.infcx.tcx.lang_items().fn_once_trait() {
                     let closure = match args.first() {
-                        Some(Operand::Copy(ref place)) | Some(Operand::Move(ref place))
+                        Some(Operand::Copy(place) | Operand::Move(place))
                             if target == place.local_or_deref_local() =>
                         {
                             place.local_or_deref_local().unwrap()
                         }
-                        _ => return,
+                        _ => return false,
                     };
 
                     debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);
@@ -125,7 +125,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                     ty::place_to_string_for_capture(self.infcx.tcx, hir_place)
                                 ),
                             );
-                            return;
+                            return true;
                         }
                     }
                 }
@@ -149,9 +149,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             ty::place_to_string_for_capture(self.infcx.tcx, hir_place)
                         ),
                     );
+                    return true;
                 }
             }
         }
+        false
     }
 
     /// End-user visible description of `place` if one can be found.
@@ -350,7 +352,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     } else {
                         def.non_enum_variant()
                     };
-                    if !including_tuple_field.0 && variant.ctor_kind == CtorKind::Fn {
+                    if !including_tuple_field.0 && variant.ctor_kind() == Some(CtorKind::Fn) {
                         return None;
                     }
                     Some(variant.fields[field.index()].name.to_string())
@@ -437,9 +439,9 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     if !is_terminator {
                         continue;
                     } else if let Some(Terminator {
-                        kind: TerminatorKind::Call { ref func, from_hir_call: false, .. },
+                        kind: TerminatorKind::Call { func, from_hir_call: false, .. },
                         ..
-                    }) = bbd.terminator
+                    }) = &bbd.terminator
                     {
                         if let Some(source) =
                             BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx)
@@ -588,22 +590,45 @@ impl UseSpans<'_> {
         }
     }
 
-    // Add a span label to the arguments of the closure, if it exists.
+    /// Add a span label to the arguments of the closure, if it exists.
     pub(super) fn args_span_label(self, err: &mut Diagnostic, message: impl Into<String>) {
         if let UseSpans::ClosureUse { args_span, .. } = self {
             err.span_label(args_span, message);
         }
     }
 
-    // Add a span label to the use of the captured variable, if it exists.
-    // only adds label to the `path_span`
-    pub(super) fn var_span_label_path_only(self, err: &mut Diagnostic, message: impl Into<String>) {
-        if let UseSpans::ClosureUse { path_span, .. } = self {
-            err.span_label(path_span, message);
+    /// Add a span label to the use of the captured variable, if it exists.
+    /// only adds label to the `path_span`
+    pub(super) fn var_path_only_subdiag(
+        self,
+        err: &mut Diagnostic,
+        action: crate::InitializationRequiringAction,
+    ) {
+        use crate::session_diagnostics::CaptureVarPathUseCause::*;
+        use crate::InitializationRequiringAction::*;
+        if let UseSpans::ClosureUse { generator_kind, path_span, .. } = self {
+            match generator_kind {
+                Some(_) => {
+                    err.subdiagnostic(match action {
+                        Borrow => BorrowInGenerator { path_span },
+                        MatchOn | Use => UseInGenerator { path_span },
+                        Assignment => AssignInGenerator { path_span },
+                        PartialAssignment => AssignPartInGenerator { path_span },
+                    });
+                }
+                None => {
+                    err.subdiagnostic(match action {
+                        Borrow => BorrowInClosure { path_span },
+                        MatchOn | Use => UseInClosure { path_span },
+                        Assignment => AssignInClosure { path_span },
+                        PartialAssignment => AssignPartInClosure { path_span },
+                    });
+                }
+            }
         }
     }
 
-    // Add a span label to the use of the captured variable, if it exists.
+    /// Add a span label to the use of the captured variable, if it exists.
     pub(super) fn var_span_label(
         self,
         err: &mut Diagnostic,
@@ -623,6 +648,35 @@ impl UseSpans<'_> {
         }
     }
 
+    /// Add a subdiagnostic to the use of the captured variable, if it exists.
+    pub(super) fn var_subdiag(
+        self,
+        err: &mut Diagnostic,
+        kind: Option<rustc_middle::mir::BorrowKind>,
+        f: impl Fn(Option<GeneratorKind>, Span) -> crate::session_diagnostics::CaptureVarCause,
+    ) {
+        use crate::session_diagnostics::CaptureVarKind::*;
+        if let UseSpans::ClosureUse { generator_kind, capture_kind_span, path_span, .. } = self {
+            if capture_kind_span != path_span {
+                err.subdiagnostic(match kind {
+                    Some(kd) => match kd {
+                        rustc_middle::mir::BorrowKind::Shared
+                        | rustc_middle::mir::BorrowKind::Shallow
+                        | rustc_middle::mir::BorrowKind::Unique => {
+                            Immute { kind_span: capture_kind_span }
+                        }
+
+                        rustc_middle::mir::BorrowKind::Mut { .. } => {
+                            Mut { kind_span: capture_kind_span }
+                        }
+                    },
+                    None => Move { kind_span: capture_kind_span },
+                });
+            };
+            err.subdiagnostic(f(generator_kind, path_span));
+        }
+    }
+
     /// Returns `false` if this place is not used in a closure.
     pub(super) fn for_closure(&self) -> bool {
         match *self {
@@ -757,33 +811,30 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         };
 
         debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);
-        if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) = stmt.kind {
-            match **kind {
-                AggregateKind::Closure(def_id, _) | AggregateKind::Generator(def_id, _, _) => {
-                    debug!("move_spans: def_id={:?} places={:?}", def_id, places);
-                    if let Some((args_span, generator_kind, capture_kind_span, path_span)) =
-                        self.closure_span(def_id, moved_place, places)
-                    {
-                        return ClosureUse {
-                            generator_kind,
-                            args_span,
-                            capture_kind_span,
-                            path_span,
-                        };
-                    }
-                }
-                _ => {}
+        if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind
+            && let AggregateKind::Closure(def_id, _) | AggregateKind::Generator(def_id, _, _) = **kind
+        {
+            debug!("move_spans: def_id={:?} places={:?}", def_id, places);
+            if let Some((args_span, generator_kind, capture_kind_span, path_span)) =
+                self.closure_span(def_id, moved_place, places)
+            {
+                return ClosureUse {
+                    generator_kind,
+                    args_span,
+                    capture_kind_span,
+                    path_span,
+                };
             }
         }
 
         // StatementKind::FakeRead only contains a def_id if they are introduced as a result
         // of pattern matching within a closure.
-        if let StatementKind::FakeRead(box (cause, ref place)) = stmt.kind {
+        if let StatementKind::FakeRead(box (cause, place)) = stmt.kind {
             match cause {
                 FakeReadCause::ForMatchedPlace(Some(closure_def_id))
                 | FakeReadCause::ForLet(Some(closure_def_id)) => {
                     debug!("move_spans: def_id={:?} place={:?}", closure_def_id, place);
-                    let places = &[Operand::Move(*place)];
+                    let places = &[Operand::Move(place)];
                     if let Some((args_span, generator_kind, capture_kind_span, path_span)) =
                         self.closure_span(closure_def_id, moved_place, places)
                     {
@@ -870,7 +921,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);
 
         let target = match self.body[location.block].statements.get(location.statement_index) {
-            Some(&Statement { kind: StatementKind::Assign(box (ref place, _)), .. }) => {
+            Some(Statement { kind: StatementKind::Assign(box (place, _)), .. }) => {
                 if let Some(local) = place.as_local() {
                     local
                 } else {
@@ -886,9 +937,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
 
         for stmt in &self.body[location.block].statements[location.statement_index + 1..] {
-            if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) =
-                stmt.kind
-            {
+            if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind {
                 let (&def_id, is_generator) = match kind {
                     box AggregateKind::Closure(def_id, _) => (def_id, false),
                     box AggregateKind::Generator(def_id, _, _) => (def_id, true),
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 8ad40c0aa..3319a8068 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -1,6 +1,4 @@
-use rustc_errors::{
-    Applicability, Diagnostic, DiagnosticBuilder, EmissionGuarantee, ErrorGuaranteed,
-};
+use rustc_errors::{Applicability, Diagnostic};
 use rustc_hir as hir;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
@@ -221,8 +219,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             PlaceRef {
                 local,
                 projection:
-                    &[
-                        ref proj_base @ ..,
+                    [
+                        proj_base @ ..,
                         ProjectionElem::Deref,
                         ProjectionElem::Field(field, _),
                         ProjectionElem::Deref,
@@ -233,7 +231,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 if let Some(span) = get_mut_span_in_struct_field(
                     self.infcx.tcx,
                     Place::ty_from(local, proj_base, self.body, self.infcx.tcx).ty,
-                    field,
+                    *field,
                 ) {
                     err.span_suggestion_verbose(
                         span,
@@ -391,13 +389,13 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             // diagnostic: if the span starts with a mutable borrow of
             // a local variable, then just suggest the user remove it.
             PlaceRef { local: _, projection: [] }
-                if {
-                    if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
-                        snippet.starts_with("&mut ")
-                    } else {
-                        false
-                    }
-                } =>
+                if self
+                    .infcx
+                    .tcx
+                    .sess
+                    .source_map()
+                    .span_to_snippet(span)
+                    .map_or(false, |snippet| snippet.starts_with("&mut ")) =>
             {
                 err.span_label(span, format!("cannot {ACT}", ACT = act));
                 err.span_suggestion(
@@ -629,25 +627,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         self.buffer_error(err);
     }
 
-    fn suggest_map_index_mut_alternatives(
-        &self,
-        ty: Ty<'_>,
-        err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
-        span: Span,
-    ) {
+    fn suggest_map_index_mut_alternatives(&self, ty: Ty<'tcx>, err: &mut Diagnostic, span: Span) {
         let Some(adt) = ty.ty_adt_def() else { return };
         let did = adt.did();
         if self.infcx.tcx.is_diagnostic_item(sym::HashMap, did)
             || self.infcx.tcx.is_diagnostic_item(sym::BTreeMap, did)
         {
-            struct V<'a, 'b, 'tcx, G: EmissionGuarantee> {
+            struct V<'a, 'tcx> {
                 assign_span: Span,
-                err: &'a mut DiagnosticBuilder<'b, G>,
+                err: &'a mut Diagnostic,
                 ty: Ty<'tcx>,
                 suggested: bool,
             }
-            impl<'a, 'b: 'a, 'hir, 'tcx, G: EmissionGuarantee> Visitor<'hir> for V<'a, 'b, 'tcx, G> {
-                fn visit_stmt(&mut self, stmt: &'hir hir::Stmt<'hir>) {
+            impl<'a, 'tcx> Visitor<'tcx> for V<'a, 'tcx> {
+                fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
                     hir::intravisit::walk_stmt(self, stmt);
                     let expr = match stmt.kind {
                         hir::StmtKind::Semi(expr) | hir::StmtKind::Expr(expr) => expr,
@@ -705,7 +698,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                     ),
                                     (rv.span.shrink_to_hi(), ")".to_string()),
                                 ],
-                            ].into_iter(),
+                            ],
                             Applicability::MachineApplicable,
                         );
                         self.suggested = true;
@@ -1218,7 +1211,7 @@ fn get_mut_span_in_struct_field<'tcx>(
         && let hir::Node::Field(field) = node
         && let hir::TyKind::Rptr(lt, hir::MutTy { mutbl: hir::Mutability::Not, ty }) = field.ty.kind
     {
-        return Some(lt.span.between(ty.span));
+        return Some(lt.ident.span.between(ty.span));
     }
 
     None
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index 15230718d..9bc2e79e2 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -2,7 +2,7 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 //! Error reporting machinery for lifetime errors.
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
@@ -21,7 +21,7 @@ use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::Region;
 use rustc_middle::ty::TypeVisitor;
 use rustc_middle::ty::{self, RegionVid, Ty};
-use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::symbol::{kw, Ident};
 use rustc_span::Span;
 
 use crate::borrowck_errors;
@@ -181,7 +181,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     // Try to convert the lower-bound region into something named we can print for the user.
                     let lower_bound_region = self.to_error_region(type_test.lower_bound);
 
-                    let type_test_span = type_test.locations.span(&self.body);
+                    let type_test_span = type_test.span;
 
                     if let Some(lower_bound_region) = lower_bound_region {
                         let generic_ty = type_test.generic_kind.to_ty(self.infcx.tcx);
@@ -276,7 +276,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn get_impl_ident_and_self_ty_from_trait(
         &self,
         def_id: DefId,
-        trait_objects: &FxHashSet<DefId>,
+        trait_objects: &FxIndexSet<DefId>,
     ) -> Option<(Ident, &'tcx hir::Ty<'tcx>)> {
         let tcx = self.infcx.tcx;
         match tcx.hir().get_if_local(def_id) {
@@ -514,9 +514,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             span: *span,
             ty_err: match output_ty.kind() {
                 ty::Closure(_, _) => FnMutReturnTypeErr::ReturnClosure { span: *span },
-                ty::Adt(def, _)
-                    if self.infcx.tcx.is_diagnostic_item(sym::gen_future, def.did()) =>
-                {
+                ty::Generator(def, ..) if self.infcx.tcx.generator_is_async(*def) => {
                     FnMutReturnTypeErr::ReturnAsyncBlock { span: *span }
                 }
                 _ => FnMutReturnTypeErr::ReturnRef { span: *span },
@@ -830,7 +828,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         };
         debug!(?param);
 
-        let mut visitor = TraitObjectVisitor(FxHashSet::default());
+        let mut visitor = TraitObjectVisitor(FxIndexSet::default());
         visitor.visit_ty(param.param_ty);
 
         let Some((ident, self_ty)) =
@@ -843,7 +841,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn suggest_constrain_dyn_trait_in_impl(
         &self,
         err: &mut Diagnostic,
-        found_dids: &FxHashSet<DefId>,
+        found_dids: &FxIndexSet<DefId>,
         ident: Ident,
         self_ty: &hir::Ty<'_>,
     ) -> bool {
@@ -923,14 +921,18 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 }
             }
             hir::ExprKind::Block(blk, _) => {
-                if let Some(ref expr) = blk.expr {
+                if let Some(expr) = blk.expr {
                     // only when the block is a closure
                     if let hir::ExprKind::Closure(hir::Closure {
                         capture_clause: hir::CaptureBy::Ref,
+                        body,
                         ..
                     }) = expr.kind
                     {
-                        closure_span = Some(expr.span.shrink_to_lo());
+                        let body = map.body(*body);
+                        if !matches!(body.generator_kind, Some(hir::GeneratorKind::Async(..))) {
+                            closure_span = Some(expr.span.shrink_to_lo());
+                        }
                     }
                 }
             }
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index c044dbaba..171e62d91 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -254,7 +254,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr))
             .or_else(|| self.give_name_if_anonymous_region_appears_in_arg_position_impl_trait(fr));
 
-        if let Some(ref value) = value {
+        if let Some(value) = &value {
             self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone());
         }
 
@@ -355,7 +355,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                     })
                 }
 
-                ty::BoundRegionKind::BrAnon(_) => None,
+                ty::BoundRegionKind::BrAnon(..) => None,
             },
 
             ty::ReLateBound(..) | ty::ReVar(..) | ty::RePlaceholder(..) | ty::ReErased => None,
@@ -576,30 +576,10 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
         let args = last_segment.args.as_ref()?;
         let lifetime =
             self.try_match_adt_and_generic_args(substs, needle_fr, args, search_stack)?;
-        match lifetime.name {
-            hir::LifetimeName::Param(_, hir::ParamName::Plain(_) | hir::ParamName::Error)
-            | hir::LifetimeName::Error
-            | hir::LifetimeName::Static => {
-                let lifetime_span = lifetime.span;
-                Some(RegionNameHighlight::MatchedAdtAndSegment(lifetime_span))
-            }
-
-            hir::LifetimeName::Param(_, hir::ParamName::Fresh)
-            | hir::LifetimeName::ImplicitObjectLifetimeDefault
-            | hir::LifetimeName::Infer => {
-                // In this case, the user left off the lifetime; so
-                // they wrote something like:
-                //
-                // ```
-                // x: Foo<T>
-                // ```
-                //
-                // where the fully elaborated form is `Foo<'_, '1,
-                // T>`. We don't consider this a match; instead we let
-                // the "fully elaborated" type fallback above handle
-                // it.
-                None
-            }
+        if lifetime.is_anonymous() {
+            None
+        } else {
+            Some(RegionNameHighlight::MatchedAdtAndSegment(lifetime.ident.span))
         }
     }
 
@@ -959,8 +939,8 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
             {
                 predicates.iter().any(|pred| {
                     match pred.kind().skip_binder() {
-                        ty::PredicateKind::Trait(data) if data.self_ty() == ty => {}
-                        ty::PredicateKind::Projection(data) if data.projection_ty.self_ty() == ty => {}
+                        ty::PredicateKind::Clause(ty::Clause::Trait(data)) if data.self_ty() == ty => {}
+                        ty::PredicateKind::Clause(ty::Clause::Projection(data)) if data.projection_ty.self_ty() == ty => {}
                         _ => return false,
                     }
                     tcx.any_free_region_meets(pred, |r| {
diff --git a/compiler/rustc_borrowck/src/diagnostics/var_name.rs b/compiler/rustc_borrowck/src/diagnostics/var_name.rs
index 9ba29f04b..b385f95b6 100644
--- a/compiler/rustc_borrowck/src/diagnostics/var_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/var_name.rs
@@ -1,3 +1,6 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
+
 use crate::Upvar;
 use crate::{nll::ToRegionVid, region_infer::RegionInferenceContext};
 use rustc_index::vec::{Idx, IndexVec};
diff --git a/compiler/rustc_borrowck/src/facts.rs b/compiler/rustc_borrowck/src/facts.rs
index 22134d5a7..51ed27c16 100644
--- a/compiler/rustc_borrowck/src/facts.rs
+++ b/compiler/rustc_borrowck/src/facts.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::location::{LocationIndex, LocationTable};
 use crate::BorrowIndex;
 use polonius_engine::AllFacts as PoloniusFacts;
diff --git a/compiler/rustc_borrowck/src/invalidation.rs b/compiler/rustc_borrowck/src/invalidation.rs
index 3157f861d..f66a7ab3c 100644
--- a/compiler/rustc_borrowck/src/invalidation.rs
+++ b/compiler/rustc_borrowck/src/invalidation.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::{self, BasicBlock, Body, Location, NonDivergingIntrinsic, Place, Rvalue};
@@ -67,9 +69,9 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 self.consume_operand(location, op);
             }
             StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(mir::CopyNonOverlapping {
-                ref src,
-                ref dst,
-                ref count,
+                src,
+                dst,
+                count,
             })) => {
                 self.consume_operand(location, src);
                 self.consume_operand(location, dst);
@@ -104,7 +106,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
         self.check_activations(location);
 
         match &terminator.kind {
-            TerminatorKind::SwitchInt { ref discr, switch_ty: _, targets: _ } => {
+            TerminatorKind::SwitchInt { discr, switch_ty: _, targets: _ } => {
                 self.consume_operand(location, discr);
             }
             TerminatorKind::Drop { place: drop_place, target: _, unwind: _ } => {
@@ -117,7 +119,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             }
             TerminatorKind::DropAndReplace {
                 place: drop_place,
-                value: ref new_value,
+                value: new_value,
                 target: _,
                 unwind: _,
             } => {
@@ -125,8 +127,8 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 self.consume_operand(location, new_value);
             }
             TerminatorKind::Call {
-                ref func,
-                ref args,
+                func,
+                args,
                 destination,
                 target: _,
                 cleanup: _,
@@ -139,15 +141,15 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 }
                 self.mutate_place(location, *destination, Deep);
             }
-            TerminatorKind::Assert { ref cond, expected: _, ref msg, target: _, cleanup: _ } => {
+            TerminatorKind::Assert { cond, expected: _, msg, target: _, cleanup: _ } => {
                 self.consume_operand(location, cond);
                 use rustc_middle::mir::AssertKind;
-                if let AssertKind::BoundsCheck { ref len, ref index } = *msg {
+                if let AssertKind::BoundsCheck { len, index } = msg {
                     self.consume_operand(location, len);
                     self.consume_operand(location, index);
                 }
             }
-            TerminatorKind::Yield { ref value, resume, resume_arg, drop: _ } => {
+            TerminatorKind::Yield { value, resume, resume_arg, drop: _ } => {
                 self.consume_operand(location, value);
 
                 // Invalidate all borrows of local places
@@ -173,25 +175,25 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             }
             TerminatorKind::InlineAsm {
                 template: _,
-                ref operands,
+                operands,
                 options: _,
                 line_spans: _,
                 destination: _,
                 cleanup: _,
             } => {
                 for op in operands {
-                    match *op {
-                        InlineAsmOperand::In { reg: _, ref value } => {
+                    match op {
+                        InlineAsmOperand::In { reg: _, value } => {
                             self.consume_operand(location, value);
                         }
                         InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
-                            if let Some(place) = place {
+                            if let &Some(place) = place {
                                 self.mutate_place(location, place, Shallow(None));
                             }
                         }
-                        InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => {
+                        InlineAsmOperand::InOut { reg: _, late: _, in_value, out_place } => {
                             self.consume_operand(location, in_value);
-                            if let Some(out_place) = out_place {
+                            if let &Some(out_place) = out_place {
                                 self.mutate_place(location, out_place, Shallow(None));
                             }
                         }
@@ -250,8 +252,8 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
 
     // Simulates consumption of an rvalue
     fn consume_rvalue(&mut self, location: Location, rvalue: &Rvalue<'tcx>) {
-        match *rvalue {
-            Rvalue::Ref(_ /*rgn*/, bk, place) => {
+        match rvalue {
+            &Rvalue::Ref(_ /*rgn*/, bk, place) => {
                 let access_kind = match bk {
                     BorrowKind::Shallow => {
                         (Shallow(Some(ArtificialField::ShallowBorrow)), Read(ReadKind::Borrow(bk)))
@@ -270,7 +272,7 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
                 self.access_place(location, place, access_kind, LocalMutationIsAllowed::No);
             }
 
-            Rvalue::AddressOf(mutability, place) => {
+            &Rvalue::AddressOf(mutability, place) => {
                 let access_kind = match mutability {
                     Mutability::Mut => (
                         Deep,
@@ -286,20 +288,19 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
 
             Rvalue::ThreadLocalRef(_) => {}
 
-            Rvalue::Use(ref operand)
-            | Rvalue::Repeat(ref operand, _)
-            | Rvalue::UnaryOp(_ /*un_op*/, ref operand)
-            | Rvalue::Cast(_ /*cast_kind*/, ref operand, _ /*ty*/)
-            | Rvalue::ShallowInitBox(ref operand, _ /*ty*/) => {
-                self.consume_operand(location, operand)
-            }
-            Rvalue::CopyForDeref(ref place) => {
-                let op = &Operand::Copy(*place);
+            Rvalue::Use(operand)
+            | Rvalue::Repeat(operand, _)
+            | Rvalue::UnaryOp(_ /*un_op*/, operand)
+            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/)
+            | Rvalue::ShallowInitBox(operand, _ /*ty*/) => self.consume_operand(location, operand),
+
+            &Rvalue::CopyForDeref(place) => {
+                let op = &Operand::Copy(place);
                 self.consume_operand(location, op);
             }
 
-            Rvalue::Len(place) | Rvalue::Discriminant(place) => {
-                let af = match *rvalue {
+            &(Rvalue::Len(place) | Rvalue::Discriminant(place)) => {
+                let af = match rvalue {
                     Rvalue::Len(..) => Some(ArtificialField::ArrayLength),
                     Rvalue::Discriminant(..) => None,
                     _ => unreachable!(),
@@ -312,15 +313,15 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> {
                 );
             }
 
-            Rvalue::BinaryOp(_bin_op, box (ref operand1, ref operand2))
-            | Rvalue::CheckedBinaryOp(_bin_op, box (ref operand1, ref operand2)) => {
+            Rvalue::BinaryOp(_bin_op, box (operand1, operand2))
+            | Rvalue::CheckedBinaryOp(_bin_op, box (operand1, operand2)) => {
                 self.consume_operand(location, operand1);
                 self.consume_operand(location, operand2);
             }
 
             Rvalue::NullaryOp(_op, _ty) => {}
 
-            Rvalue::Aggregate(_, ref operands) => {
+            Rvalue::Aggregate(_, operands) => {
                 for operand in operands {
                     self.consume_operand(location, operand);
                 }
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index abfe253d4..74b4e4a0c 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -18,7 +18,8 @@ extern crate tracing;
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::dominators::Dominators;
-use rustc_errors::{Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_data_structures::vec_map::VecMap;
+use rustc_errors::{Diagnostic, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::bit_set::ChunkedBitSet;
@@ -82,7 +83,7 @@ mod type_check;
 mod universal_regions;
 mod used_muts;
 
-// A public API provided for the Rust compiler consumers.
+/// A public API provided for the Rust compiler consumers.
 pub mod consumers;
 
 use borrow_set::{BorrowData, BorrowSet};
@@ -129,6 +130,19 @@ fn mir_borrowck<'tcx>(
 ) -> &'tcx BorrowCheckResult<'tcx> {
     let (input_body, promoted) = tcx.mir_promoted(def);
     debug!("run query mir_borrowck: {}", tcx.def_path_str(def.did.to_def_id()));
+
+    if input_body.borrow().should_skip() {
+        debug!("Skipping borrowck because of injected body");
+        // Let's make up a borrowck result! Fun times!
+        let result = BorrowCheckResult {
+            concrete_opaque_types: VecMap::new(),
+            closure_requirements: None,
+            used_mut_upvars: SmallVec::new(),
+            tainted_by_errors: None,
+        };
+        return tcx.arena.alloc(result);
+    }
+
     let hir_owner = tcx.hir().local_def_id_to_hir_id(def.did).owner;
 
     let infcx =
@@ -178,13 +192,13 @@ fn do_mir_borrowck<'tcx>(
         }
     }
 
-    let mut errors = error::BorrowckErrors::new();
+    let mut errors = error::BorrowckErrors::new(infcx.tcx);
 
     // Gather the upvars of a closure, if any.
     let tables = tcx.typeck_opt_const_arg(def);
-    if let Some(ErrorGuaranteed { .. }) = tables.tainted_by_errors {
-        infcx.set_tainted_by_errors();
-        errors.set_tainted_by_errors();
+    if let Some(e) = tables.tainted_by_errors {
+        infcx.set_tainted_by_errors(e);
+        errors.set_tainted_by_errors(e);
     }
     let upvars: Vec<_> = tables
         .closure_min_captures_flattened(def.did)
@@ -564,12 +578,12 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
         self.check_activations(location, span, flow_state);
 
         match &stmt.kind {
-            StatementKind::Assign(box (lhs, ref rhs)) => {
+            StatementKind::Assign(box (lhs, rhs)) => {
                 self.consume_rvalue(location, (rhs, span), flow_state);
 
                 self.mutate_place(location, (*lhs, span), Shallow(None), flow_state);
             }
-            StatementKind::FakeRead(box (_, ref place)) => {
+            StatementKind::FakeRead(box (_, place)) => {
                 // Read for match doesn't access any memory and is used to
                 // assert that a place is safe and live. So we don't have to
                 // do any checks here.
@@ -587,7 +601,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                     flow_state,
                 );
             }
-            StatementKind::Intrinsic(box ref kind) => match kind {
+            StatementKind::Intrinsic(box kind) => match kind {
                 NonDivergingIntrinsic::Assume(op) => self.consume_operand(location, (op, span), flow_state),
                 NonDivergingIntrinsic::CopyNonOverlapping(..) => span_bug!(
                     span,
@@ -629,8 +643,8 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
 
         self.check_activations(loc, span, flow_state);
 
-        match term.kind {
-            TerminatorKind::SwitchInt { ref discr, switch_ty: _, targets: _ } => {
+        match &term.kind {
+            TerminatorKind::SwitchInt { discr, switch_ty: _, targets: _ } => {
                 self.consume_operand(loc, (discr, span), flow_state);
             }
             TerminatorKind::Drop { place, target: _, unwind: _ } => {
@@ -642,7 +656,7 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
 
                 self.access_place(
                     loc,
-                    (place, span),
+                    (*place, span),
                     (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)),
                     LocalMutationIsAllowed::Yes,
                     flow_state,
@@ -650,16 +664,16 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
             }
             TerminatorKind::DropAndReplace {
                 place: drop_place,
-                value: ref new_value,
+                value: new_value,
                 target: _,
                 unwind: _,
             } => {
-                self.mutate_place(loc, (drop_place, span), Deep, flow_state);
+                self.mutate_place(loc, (*drop_place, span), Deep, flow_state);
                 self.consume_operand(loc, (new_value, span), flow_state);
             }
             TerminatorKind::Call {
-                ref func,
-                ref args,
+                func,
+                args,
                 destination,
                 target: _,
                 cleanup: _,
@@ -670,43 +684,43 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                 for arg in args {
                     self.consume_operand(loc, (arg, span), flow_state);
                 }
-                self.mutate_place(loc, (destination, span), Deep, flow_state);
+                self.mutate_place(loc, (*destination, span), Deep, flow_state);
             }
-            TerminatorKind::Assert { ref cond, expected: _, ref msg, target: _, cleanup: _ } => {
+            TerminatorKind::Assert { cond, expected: _, msg, target: _, cleanup: _ } => {
                 self.consume_operand(loc, (cond, span), flow_state);
                 use rustc_middle::mir::AssertKind;
-                if let AssertKind::BoundsCheck { ref len, ref index } = *msg {
+                if let AssertKind::BoundsCheck { len, index } = msg {
                     self.consume_operand(loc, (len, span), flow_state);
                     self.consume_operand(loc, (index, span), flow_state);
                 }
             }
 
-            TerminatorKind::Yield { ref value, resume: _, resume_arg, drop: _ } => {
+            TerminatorKind::Yield { value, resume: _, resume_arg, drop: _ } => {
                 self.consume_operand(loc, (value, span), flow_state);
-                self.mutate_place(loc, (resume_arg, span), Deep, flow_state);
+                self.mutate_place(loc, (*resume_arg, span), Deep, flow_state);
             }
 
             TerminatorKind::InlineAsm {
                 template: _,
-                ref operands,
+                operands,
                 options: _,
                 line_spans: _,
                 destination: _,
                 cleanup: _,
             } => {
                 for op in operands {
-                    match *op {
-                        InlineAsmOperand::In { reg: _, ref value } => {
+                    match op {
+                        InlineAsmOperand::In { reg: _, value } => {
                             self.consume_operand(loc, (value, span), flow_state);
                         }
                         InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
                             if let Some(place) = place {
-                                self.mutate_place(loc, (place, span), Shallow(None), flow_state);
+                                self.mutate_place(loc, (*place, span), Shallow(None), flow_state);
                             }
                         }
-                        InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => {
+                        InlineAsmOperand::InOut { reg: _, late: _, in_value, out_place } => {
                             self.consume_operand(loc, (in_value, span), flow_state);
-                            if let Some(out_place) = out_place {
+                            if let &Some(out_place) = out_place {
                                 self.mutate_place(
                                     loc,
                                     (out_place, span),
@@ -1150,8 +1164,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         (rvalue, span): (&'cx Rvalue<'tcx>, Span),
         flow_state: &Flows<'cx, 'tcx>,
     ) {
-        match *rvalue {
-            Rvalue::Ref(_ /*rgn*/, bk, place) => {
+        match rvalue {
+            &Rvalue::Ref(_ /*rgn*/, bk, place) => {
                 let access_kind = match bk {
                     BorrowKind::Shallow => {
                         (Shallow(Some(ArtificialField::ShallowBorrow)), Read(ReadKind::Borrow(bk)))
@@ -1189,7 +1203,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 );
             }
 
-            Rvalue::AddressOf(mutability, place) => {
+            &Rvalue::AddressOf(mutability, place) => {
                 let access_kind = match mutability {
                     Mutability::Mut => (
                         Deep,
@@ -1218,14 +1232,15 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
             Rvalue::ThreadLocalRef(_) => {}
 
-            Rvalue::Use(ref operand)
-            | Rvalue::Repeat(ref operand, _)
-            | Rvalue::UnaryOp(_ /*un_op*/, ref operand)
-            | Rvalue::Cast(_ /*cast_kind*/, ref operand, _ /*ty*/)
-            | Rvalue::ShallowInitBox(ref operand, _ /*ty*/) => {
+            Rvalue::Use(operand)
+            | Rvalue::Repeat(operand, _)
+            | Rvalue::UnaryOp(_ /*un_op*/, operand)
+            | Rvalue::Cast(_ /*cast_kind*/, operand, _ /*ty*/)
+            | Rvalue::ShallowInitBox(operand, _ /*ty*/) => {
                 self.consume_operand(location, (operand, span), flow_state)
             }
-            Rvalue::CopyForDeref(place) => {
+
+            &Rvalue::CopyForDeref(place) => {
                 self.access_place(
                     location,
                     (place, span),
@@ -1243,7 +1258,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 );
             }
 
-            Rvalue::Len(place) | Rvalue::Discriminant(place) => {
+            &(Rvalue::Len(place) | Rvalue::Discriminant(place)) => {
                 let af = match *rvalue {
                     Rvalue::Len(..) => Some(ArtificialField::ArrayLength),
                     Rvalue::Discriminant(..) => None,
@@ -1264,8 +1279,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 );
             }
 
-            Rvalue::BinaryOp(_bin_op, box (ref operand1, ref operand2))
-            | Rvalue::CheckedBinaryOp(_bin_op, box (ref operand1, ref operand2)) => {
+            Rvalue::BinaryOp(_bin_op, box (operand1, operand2))
+            | Rvalue::CheckedBinaryOp(_bin_op, box (operand1, operand2)) => {
                 self.consume_operand(location, (operand1, span), flow_state);
                 self.consume_operand(location, (operand2, span), flow_state);
             }
@@ -1274,7 +1289,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 // nullary ops take no dynamic input; no borrowck effect.
             }
 
-            Rvalue::Aggregate(ref aggregate_kind, ref operands) => {
+            Rvalue::Aggregate(aggregate_kind, operands) => {
                 // We need to report back the list of mutable upvars that were
                 // moved into the closure and subsequently used by the closure,
                 // in order to populate our used_mut set.
@@ -2246,6 +2261,7 @@ mod error {
     use super::*;
 
     pub struct BorrowckErrors<'tcx> {
+        tcx: TyCtxt<'tcx>,
         /// This field keeps track of move errors that are to be reported for given move indices.
         ///
         /// There are situations where many errors can be reported for a single move out (see #53807)
@@ -2268,19 +2284,24 @@ mod error {
         tainted_by_errors: Option<ErrorGuaranteed>,
     }
 
-    impl BorrowckErrors<'_> {
-        pub fn new() -> Self {
+    impl<'tcx> BorrowckErrors<'tcx> {
+        pub fn new(tcx: TyCtxt<'tcx>) -> Self {
             BorrowckErrors {
+                tcx,
                 buffered_move_errors: BTreeMap::new(),
                 buffered: Default::default(),
                 tainted_by_errors: None,
             }
         }
 
-        // FIXME(eddyb) this is a suboptimal API because `tainted_by_errors` is
-        // set before any emission actually happens (weakening the guarantee).
         pub fn buffer_error(&mut self, t: DiagnosticBuilder<'_, ErrorGuaranteed>) {
-            self.tainted_by_errors = Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
+            if let None = self.tainted_by_errors {
+                self.tainted_by_errors = Some(
+                    self.tcx
+                        .sess
+                        .delay_span_bug(t.span.clone(), "diagnostic buffered but not emitted"),
+                )
+            }
             t.buffer(&mut self.buffered);
         }
 
@@ -2288,8 +2309,8 @@ mod error {
             t.buffer(&mut self.buffered);
         }
 
-        pub fn set_tainted_by_errors(&mut self) {
-            self.tainted_by_errors = Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
+        pub fn set_tainted_by_errors(&mut self, e: ErrorGuaranteed) {
+            self.tainted_by_errors = Some(e);
         }
     }
 
diff --git a/compiler/rustc_borrowck/src/location.rs b/compiler/rustc_borrowck/src/location.rs
index 877944d3d..9fa7e218b 100644
--- a/compiler/rustc_borrowck/src/location.rs
+++ b/compiler/rustc_borrowck/src/location.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::mir::{BasicBlock, Body, Location};
 
diff --git a/compiler/rustc_borrowck/src/member_constraints.rs b/compiler/rustc_borrowck/src/member_constraints.rs
index 43253a2aa..b5e00f471 100644
--- a/compiler/rustc_borrowck/src/member_constraints.rs
+++ b/compiler/rustc_borrowck/src/member_constraints.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::vec::IndexVec;
@@ -9,6 +11,7 @@ use std::ops::Index;
 
 /// Compactly stores a set of `R0 member of [R1...Rn]` constraints,
 /// indexed by the region `R0`.
+#[derive(Debug)]
 pub(crate) struct MemberConstraintSet<'tcx, R>
 where
     R: Copy + Eq,
@@ -29,6 +32,7 @@ where
 }
 
 /// Represents a `R0 member of [R1..Rn]` constraint
+#[derive(Debug)]
 pub(crate) struct NllMemberConstraint<'tcx> {
     next_constraint: Option<NllMemberConstraintIndex>,
 
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 08fdd28eb..e379e6470 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! The entry point of the NLL borrow checker.
 
 use rustc_data_structures::vec_map::VecMap;
@@ -71,7 +73,7 @@ pub(crate) fn replace_regions_in_mir<'tcx>(
     // Replace all remaining regions with fresh inference variables.
     renumber::renumber_mir(infcx, body, promoted);
 
-    dump_mir(infcx.tcx, None, "renumber", &0, body, |_, _| Ok(()));
+    dump_mir(infcx.tcx, false, "renumber", &0, body, |_, _| Ok(()));
 
     universal_regions
 }
@@ -242,7 +244,6 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
         mut liveness_constraints,
         outlives_constraints,
         member_constraints,
-        closure_bounds_mapping,
         universe_causes,
         type_tests,
     } = constraints;
@@ -264,7 +265,6 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
         universal_region_relations,
         outlives_constraints,
         member_constraints,
-        closure_bounds_mapping,
         universe_causes,
         type_tests,
         liveness_constraints,
@@ -303,7 +303,10 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
 
     if !nll_errors.is_empty() {
         // Suppress unhelpful extra errors in `infer_opaque_types`.
-        infcx.set_tainted_by_errors();
+        infcx.set_tainted_by_errors(infcx.tcx.sess.delay_span_bug(
+            body.span,
+            "`compute_regions` tainted `infcx` with errors but did not emit any errors",
+        ));
     }
 
     let remapped_opaque_tys = regioncx.infer_opaque_types(&infcx, opaque_type_values);
@@ -328,7 +331,7 @@ pub(super) fn dump_mir_results<'tcx>(
         return;
     }
 
-    dump_mir(infcx.tcx, None, "nll", &0, body, |pass_where, out| {
+    dump_mir(infcx.tcx, false, "nll", &0, body, |pass_where, out| {
         match pass_where {
             // Before the CFG, dump out the values for each region variable.
             PassWhere::BeforeCFG => {
@@ -355,15 +358,13 @@ pub(super) fn dump_mir_results<'tcx>(
 
     // Also dump the inference graph constraints as a graphviz file.
     let _: io::Result<()> = try {
-        let mut file =
-            create_dump_file(infcx.tcx, "regioncx.all.dot", None, "nll", &0, body.source)?;
+        let mut file = create_dump_file(infcx.tcx, "regioncx.all.dot", false, "nll", &0, body)?;
         regioncx.dump_graphviz_raw_constraints(&mut file)?;
     };
 
     // Also dump the inference graph constraints as a graphviz file.
     let _: io::Result<()> = try {
-        let mut file =
-            create_dump_file(infcx.tcx, "regioncx.scc.dot", None, "nll", &0, body.source)?;
+        let mut file = create_dump_file(infcx.tcx, "regioncx.scc.dot", false, "nll", &0, body)?;
         regioncx.dump_graphviz_scc_constraints(&mut file)?;
     };
 }
diff --git a/compiler/rustc_borrowck/src/path_utils.rs b/compiler/rustc_borrowck/src/path_utils.rs
index b2c8dfc82..f8a99a269 100644
--- a/compiler/rustc_borrowck/src/path_utils.rs
+++ b/compiler/rustc_borrowck/src/path_utils.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::borrow_set::{BorrowData, BorrowSet, TwoPhaseActivation};
 use crate::places_conflict;
 use crate::AccessDepth;
diff --git a/compiler/rustc_borrowck/src/place_ext.rs b/compiler/rustc_borrowck/src/place_ext.rs
index 93d202e49..9f6b1fdfc 100644
--- a/compiler/rustc_borrowck/src/place_ext.rs
+++ b/compiler/rustc_borrowck/src/place_ext.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::borrow_set::LocalsStateAtExit;
 use rustc_hir as hir;
 use rustc_middle::mir::ProjectionElem;
diff --git a/compiler/rustc_borrowck/src/places_conflict.rs b/compiler/rustc_borrowck/src/places_conflict.rs
index 0e71efd6f..89ac0dfa4 100644
--- a/compiler/rustc_borrowck/src/places_conflict.rs
+++ b/compiler/rustc_borrowck/src/places_conflict.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::ArtificialField;
 use crate::Overlap;
 use crate::{AccessDepth, Deep, Shallow};
@@ -318,16 +320,10 @@ fn place_projection_conflict<'tcx>(
             debug!("place_element_conflict: DISJOINT-OR-EQ-DEREF");
             Overlap::EqualOrDisjoint
         }
-        (ProjectionElem::OpaqueCast(v1), ProjectionElem::OpaqueCast(v2)) => {
-            if v1 == v2 {
-                // same type - recur.
-                debug!("place_element_conflict: DISJOINT-OR-EQ-OPAQUE");
-                Overlap::EqualOrDisjoint
-            } else {
-                // Different types. Disjoint!
-                debug!("place_element_conflict: DISJOINT-OPAQUE");
-                Overlap::Disjoint
-            }
+        (ProjectionElem::OpaqueCast(_), ProjectionElem::OpaqueCast(_)) => {
+            // casts to other types may always conflict irrespective of the type being cast to.
+            debug!("place_element_conflict: DISJOINT-OR-EQ-OPAQUE");
+            Overlap::EqualOrDisjoint
         }
         (ProjectionElem::Field(f1, _), ProjectionElem::Field(f2, _)) => {
             if f1 == f2 {
diff --git a/compiler/rustc_borrowck/src/prefixes.rs b/compiler/rustc_borrowck/src/prefixes.rs
index 2b50cbac9..6f2813498 100644
--- a/compiler/rustc_borrowck/src/prefixes.rs
+++ b/compiler/rustc_borrowck/src/prefixes.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! From the NLL RFC: "The deep [aka 'supporting'] prefixes for an
 //! place are formed by stripping away fields and derefs, except that
 //! we stop when we reach the deref of a shared reference. [...] "
diff --git a/compiler/rustc_borrowck/src/region_infer/dump_mir.rs b/compiler/rustc_borrowck/src/region_infer/dump_mir.rs
index fe5193102..6524b594e 100644
--- a/compiler/rustc_borrowck/src/region_infer/dump_mir.rs
+++ b/compiler/rustc_borrowck/src/region_infer/dump_mir.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! As part of generating the regions, if you enable `-Zdump-mir=nll`,
 //! we will generate an annotated copy of the MIR that includes the
 //! state of region inference. This code handles emitting the region
@@ -74,8 +76,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let mut constraints: Vec<_> = self.constraints.outlives().iter().collect();
         constraints.sort_by_key(|c| (c.sup, c.sub));
         for constraint in &constraints {
-            let OutlivesConstraint { sup, sub, locations, category, span, variance_info: _ } =
-                constraint;
+            let OutlivesConstraint { sup, sub, locations, category, span, .. } = constraint;
             let (name, arg) = match locations {
                 Locations::All(span) => {
                     ("All", tcx.sess.source_map().span_to_embeddable_string(*span))
diff --git a/compiler/rustc_borrowck/src/region_infer/graphviz.rs b/compiler/rustc_borrowck/src/region_infer/graphviz.rs
index f31ccd74c..2e15586e0 100644
--- a/compiler/rustc_borrowck/src/region_infer/graphviz.rs
+++ b/compiler/rustc_borrowck/src/region_infer/graphviz.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! This module provides linkage between RegionInferenceContext and
 //! `rustc_graphviz` traits, specialized to attaching borrowck analysis
 //! data to rendered labels.
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 8b63294fb..90e2b6b69 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -6,10 +6,9 @@ use rustc_data_structures::frozen::Frozen;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::scc::Sccs;
 use rustc_errors::Diagnostic;
-use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
+use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_hir::CRATE_HIR_ID;
 use rustc_index::vec::IndexVec;
-use rustc_infer::infer::canonical::QueryOutlivesConstraint;
 use rustc_infer::infer::outlives::test_type_match;
 use rustc_infer::infer::region_constraints::{GenericKind, VarInfos, VerifyBound, VerifyIfEq};
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, RegionVariableOrigin};
@@ -19,9 +18,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::ObligationCauseCode;
-use rustc_middle::ty::{
-    self, subst::SubstsRef, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitable,
-};
+use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitable};
 use rustc_span::Span;
 
 use crate::{
@@ -89,10 +86,6 @@ pub struct RegionInferenceContext<'tcx> {
     /// `member_region_scc`.
     member_constraints_applied: Vec<AppliedMemberConstraint>,
 
-    /// Map closure bounds to a `Span` that should be used for error reporting.
-    closure_bounds_mapping:
-        FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory<'tcx>, Span)>>,
-
     /// Map universe indexes to information on why we created it.
     universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
 
@@ -135,6 +128,7 @@ pub struct RegionInferenceContext<'tcx> {
 /// adds a new lower bound to the SCC it is analyzing: so you wind up
 /// with `'R: 'O` where `'R` is the pick-region and `'O` is the
 /// minimal viable option.
+#[derive(Debug)]
 pub(crate) struct AppliedMemberConstraint {
     /// The SCC that was affected. (The "member region".)
     ///
@@ -221,8 +215,8 @@ pub struct TypeTest<'tcx> {
     /// The region `'x` that the type must outlive.
     pub lower_bound: RegionVid,
 
-    /// Where did this constraint arise and why?
-    pub locations: Locations,
+    /// The span to blame.
+    pub span: Span,
 
     /// A test which, if met by the region `'x`, proves that this type
     /// constraint is satisfied.
@@ -265,10 +259,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
         outlives_constraints: OutlivesConstraintSet<'tcx>,
         member_constraints_in: MemberConstraintSet<'tcx, RegionVid>,
-        closure_bounds_mapping: FxHashMap<
-            Location,
-            FxHashMap<(RegionVid, RegionVid), (ConstraintCategory<'tcx>, Span)>,
-        >,
         universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
         type_tests: Vec<TypeTest<'tcx>>,
         liveness_constraints: LivenessValues<RegionVid>,
@@ -310,7 +300,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             rev_scc_graph: None,
             member_constraints,
             member_constraints_applied: Vec::new(),
-            closure_bounds_mapping,
             universe_causes,
             scc_universes,
             scc_representatives,
@@ -882,13 +871,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             if deduplicate_errors.insert((
                 erased_generic_kind,
                 type_test.lower_bound,
-                type_test.locations,
+                type_test.span,
             )) {
                 debug!(
                     "check_type_test: reporting error for erased_generic_kind={:?}, \
                      lower_bound_region={:?}, \
-                     type_test.locations={:?}",
-                    erased_generic_kind, type_test.lower_bound, type_test.locations,
+                     type_test.span={:?}",
+                    erased_generic_kind, type_test.lower_bound, type_test.span,
                 );
 
                 errors_buffer.push(RegionErrorKind::TypeTestError { type_test: type_test.clone() });
@@ -931,7 +920,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ) -> bool {
         let tcx = infcx.tcx;
 
-        let TypeTest { generic_kind, lower_bound, locations, verify_bound: _ } = type_test;
+        let TypeTest { generic_kind, lower_bound, span: _, verify_bound: _ } = type_test;
 
         let generic_ty = generic_kind.to_ty(tcx);
         let Some(subject) = self.try_promote_type_test_subject(infcx, generic_ty) else {
@@ -959,7 +948,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             propagated_outlives_requirements.push(ClosureOutlivesRequirement {
                 subject,
                 outlived_free_region: static_r,
-                blame_span: locations.span(body),
+                blame_span: type_test.span,
                 category: ConstraintCategory::Boring,
             });
 
@@ -1011,7 +1000,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 let requirement = ClosureOutlivesRequirement {
                     subject,
                     outlived_free_region: upper_bound,
-                    blame_span: locations.span(body),
+                    blame_span: type_test.span,
                     category: ConstraintCategory::Boring,
                 };
                 debug!("try_promote_type_test: pushing {:#?}", requirement);
@@ -1716,6 +1705,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         });
     }
 
+    #[instrument(level = "debug", skip(self, infcx, errors_buffer))]
     fn check_member_constraints(
         &self,
         infcx: &InferCtxt<'tcx>,
@@ -1723,22 +1713,21 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ) {
         let member_constraints = self.member_constraints.clone();
         for m_c_i in member_constraints.all_indices() {
-            debug!("check_member_constraint(m_c_i={:?})", m_c_i);
+            debug!(?m_c_i);
             let m_c = &member_constraints[m_c_i];
             let member_region_vid = m_c.member_region_vid;
             debug!(
-                "check_member_constraint: member_region_vid={:?} with value {}",
-                member_region_vid,
-                self.region_value_str(member_region_vid),
+                ?member_region_vid,
+                value = ?self.region_value_str(member_region_vid),
             );
             let choice_regions = member_constraints.choice_regions(m_c_i);
-            debug!("check_member_constraint: choice_regions={:?}", choice_regions);
+            debug!(?choice_regions);
 
             // Did the member region wind up equal to any of the option regions?
             if let Some(o) =
                 choice_regions.iter().find(|&&o_r| self.eval_equal(o_r, m_c.member_region_vid))
             {
-                debug!("check_member_constraint: evaluated as equal to {:?}", o);
+                debug!("evaluated as equal to {:?}", o);
                 continue;
             }
 
@@ -1804,18 +1793,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         }
     }
 
-    pub(crate) fn retrieve_closure_constraint_info(
-        &self,
-        constraint: OutlivesConstraint<'tcx>,
-    ) -> Option<(ConstraintCategory<'tcx>, Span)> {
-        match constraint.locations {
-            Locations::All(_) => None,
-            Locations::Single(loc) => {
-                self.closure_bounds_mapping[&loc].get(&(constraint.sup, constraint.sub)).copied()
-            }
-        }
-    }
-
     /// Finds a good `ObligationCause` to blame for the fact that `fr1` outlives `fr2`.
     pub(crate) fn find_outlives_blame_span(
         &self,
@@ -1921,6 +1898,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     span: p_c.definition_span,
                     category: ConstraintCategory::OpaqueType,
                     variance_info: ty::VarianceDiagInfo::default(),
+                    from_closure: false,
                 };
                 handle_constraint(constraint);
             }
@@ -2066,31 +2044,12 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // Classify each of the constraints along the path.
         let mut categorized_path: Vec<BlameConstraint<'tcx>> = path
             .iter()
-            .map(|constraint| {
-                let (category, span, from_closure, cause_code) =
-                    if constraint.category == ConstraintCategory::ClosureBounds {
-                        if let Some((category, span)) =
-                            self.retrieve_closure_constraint_info(*constraint)
-                        {
-                            (category, span, true, ObligationCauseCode::MiscObligation)
-                        } else {
-                            (
-                                constraint.category,
-                                constraint.span,
-                                false,
-                                ObligationCauseCode::MiscObligation,
-                            )
-                        }
-                    } else {
-                        (constraint.category, constraint.span, false, cause_code.clone())
-                    };
-                BlameConstraint {
-                    category,
-                    from_closure,
-                    cause: ObligationCause::new(span, CRATE_HIR_ID, cause_code),
-                    variance_info: constraint.variance_info,
-                    outlives_constraint: *constraint,
-                }
+            .map(|constraint| BlameConstraint {
+                category: constraint.category,
+                from_closure: constraint.from_closure,
+                cause: ObligationCause::new(constraint.span, CRATE_HIR_ID, cause_code.clone()),
+                variance_info: constraint.variance_info,
+                outlives_constraint: *constraint,
             })
             .collect();
         debug!("categorized_path={:#?}", categorized_path);
@@ -2274,92 +2233,6 @@ impl<'tcx> RegionDefinition<'tcx> {
     }
 }
 
-pub trait ClosureRegionRequirementsExt<'tcx> {
-    fn apply_requirements(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        closure_def_id: DefId,
-        closure_substs: SubstsRef<'tcx>,
-    ) -> Vec<QueryOutlivesConstraint<'tcx>>;
-}
-
-impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx> {
-    /// Given an instance T of the closure type, this method
-    /// instantiates the "extra" requirements that we computed for the
-    /// closure into the inference context. This has the effect of
-    /// adding new outlives obligations to existing variables.
-    ///
-    /// As described on `ClosureRegionRequirements`, the extra
-    /// requirements are expressed in terms of regionvids that index
-    /// into the free regions that appear on the closure type. So, to
-    /// do this, we first copy those regions out from the type T into
-    /// a vector. Then we can just index into that vector to extract
-    /// out the corresponding region from T and apply the
-    /// requirements.
-    fn apply_requirements(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        closure_def_id: DefId,
-        closure_substs: SubstsRef<'tcx>,
-    ) -> Vec<QueryOutlivesConstraint<'tcx>> {
-        debug!(
-            "apply_requirements(closure_def_id={:?}, closure_substs={:?})",
-            closure_def_id, closure_substs
-        );
-
-        // Extract the values of the free regions in `closure_substs`
-        // into a vector.  These are the regions that we will be
-        // relating to one another.
-        let closure_mapping = &UniversalRegions::closure_mapping(
-            tcx,
-            closure_substs,
-            self.num_external_vids,
-            tcx.typeck_root_def_id(closure_def_id),
-        );
-        debug!("apply_requirements: closure_mapping={:?}", closure_mapping);
-
-        // Create the predicates.
-        self.outlives_requirements
-            .iter()
-            .map(|outlives_requirement| {
-                let outlived_region = closure_mapping[outlives_requirement.outlived_free_region];
-
-                match outlives_requirement.subject {
-                    ClosureOutlivesSubject::Region(region) => {
-                        let region = closure_mapping[region];
-                        debug!(
-                            "apply_requirements: region={:?} \
-                             outlived_region={:?} \
-                             outlives_requirement={:?}",
-                            region, outlived_region, outlives_requirement,
-                        );
-                        (
-                            ty::Binder::dummy(ty::OutlivesPredicate(
-                                region.into(),
-                                outlived_region,
-                            )),
-                            ConstraintCategory::BoringNoLocation,
-                        )
-                    }
-
-                    ClosureOutlivesSubject::Ty(ty) => {
-                        debug!(
-                            "apply_requirements: ty={:?} \
-                             outlived_region={:?} \
-                             outlives_requirement={:?}",
-                            ty, outlived_region, outlives_requirement,
-                        );
-                        (
-                            ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), outlived_region)),
-                            ConstraintCategory::BoringNoLocation,
-                        )
-                    }
-                }
-            })
-            .collect()
-    }
-}
-
 #[derive(Clone, Debug)]
 pub struct BlameConstraint<'tcx> {
     pub category: ConstraintCategory<'tcx>,
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index 465f353aa..516a08077 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -1,18 +1,16 @@
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_data_structures::vec_map::VecMap;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::OpaqueTyOrigin;
 use rustc_infer::infer::TyCtxtInferExt as _;
 use rustc_infer::infer::{DefiningAnchor, InferCtxt};
-use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine};
+use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
 use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{
-    self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt, TypeFoldable,
-};
+use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
-use rustc_trait_selection::traits::TraitEngineExt as _;
+use rustc_trait_selection::traits::ObligationCtxt;
 
 use super::RegionInferenceContext;
 
@@ -63,17 +61,21 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         opaque_ty_decls: VecMap<OpaqueTypeKey<'tcx>, (OpaqueHiddenType<'tcx>, OpaqueTyOrigin)>,
     ) -> VecMap<LocalDefId, OpaqueHiddenType<'tcx>> {
         let mut result: VecMap<LocalDefId, OpaqueHiddenType<'tcx>> = VecMap::new();
+
+        let member_constraints: FxHashMap<_, _> = self
+            .member_constraints
+            .all_indices()
+            .map(|ci| (self.member_constraints[ci].key, ci))
+            .collect();
+        debug!(?member_constraints);
+
         for (opaque_type_key, (concrete_type, origin)) in opaque_ty_decls {
             let substs = opaque_type_key.substs;
             debug!(?concrete_type, ?substs);
 
             let mut subst_regions = vec![self.universal_regions.fr_static];
-            let universal_substs = infcx.tcx.fold_regions(substs, |region, _| {
-                if let ty::RePlaceholder(..) = region.kind() {
-                    // Higher kinded regions don't need remapping, they don't refer to anything outside of this the substs.
-                    return region;
-                }
-                let vid = self.to_region_vid(region);
+
+            let to_universal_region = |vid, subst_regions: &mut Vec<_>| {
                 trace!(?vid);
                 let scc = self.constraint_sccs.scc(vid);
                 trace!(?scc);
@@ -94,10 +96,33 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         infcx.tcx.lifetimes.re_static
                     }
                 }
+            };
+
+            // Start by inserting universal regions from the member_constraint choice regions.
+            // This will ensure they get precedence when folding the regions in the concrete type.
+            if let Some(&ci) = member_constraints.get(&opaque_type_key) {
+                for &vid in self.member_constraints.choice_regions(ci) {
+                    to_universal_region(vid, &mut subst_regions);
+                }
+            }
+            debug!(?subst_regions);
+
+            // Next, insert universal regions from substs, so we can translate regions that appear
+            // in them but are not subject to member constraints, for instance closure substs.
+            let universal_substs = infcx.tcx.fold_regions(substs, |region, _| {
+                if let ty::RePlaceholder(..) = region.kind() {
+                    // Higher kinded regions don't need remapping, they don't refer to anything outside of this the substs.
+                    return region;
+                }
+                let vid = self.to_region_vid(region);
+                to_universal_region(vid, &mut subst_regions)
             });
+            debug!(?universal_substs);
+            debug!(?subst_regions);
 
-            subst_regions.sort();
-            subst_regions.dedup();
+            // Deduplicate the set of regions while keeping the chosen order.
+            let subst_regions = subst_regions.into_iter().collect::<FxIndexSet<_>>();
+            debug!(?subst_regions);
 
             let universal_concrete_type =
                 infcx.tcx.fold_regions(concrete_type, |region, _| match *region {
@@ -108,8 +133,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         .unwrap_or(infcx.tcx.lifetimes.re_erased),
                     _ => region,
                 });
-
-            debug!(?universal_concrete_type, ?universal_substs);
+            debug!(?universal_concrete_type);
 
             let opaque_type_key =
                 OpaqueTypeKey { def_id: opaque_type_key.def_id, substs: universal_substs };
@@ -221,12 +245,12 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         instantiated_ty: OpaqueHiddenType<'tcx>,
         origin: OpaqueTyOrigin,
     ) -> Ty<'tcx> {
-        if self.is_tainted_by_errors() {
-            return self.tcx.ty_error();
+        if let Some(e) = self.tainted_by_errors() {
+            return self.tcx.ty_error_with_guaranteed(e);
         }
 
         let definition_ty = instantiated_ty
-            .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false, origin)
+            .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false)
             .ty;
 
         if !check_opaque_type_parameter_valid(
@@ -252,48 +276,45 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         // type-alias-impl-trait/issue-67844-nested-opaque.rs
         let infcx =
             self.tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).build();
+        let ocx = ObligationCtxt::new(&infcx);
         // Require the hidden type to be well-formed with only the generics of the opaque type.
         // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
         // hidden type is well formed even without those bounds.
-        let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into()))
-            .to_predicate(infcx.tcx);
-        let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
+        let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into()));
 
         let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id.to_def_id());
 
         // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
         // the bounds that the function supplies.
         let opaque_ty = self.tcx.mk_opaque(def_id.to_def_id(), id_substs);
-        match infcx
-            .at(&ObligationCause::misc(instantiated_ty.span, body_id), param_env)
-            .eq(opaque_ty, definition_ty)
-        {
-            Ok(infer_ok) => {
-                for obligation in infer_ok.obligations {
-                    fulfillment_cx.register_predicate_obligation(&infcx, obligation);
-                }
-            }
-            Err(err) => {
-                infcx
-                    .err_ctxt()
-                    .report_mismatched_types(
-                        &ObligationCause::misc(instantiated_ty.span, body_id),
-                        opaque_ty,
-                        definition_ty,
-                        err,
-                    )
-                    .emit();
-            }
+        if let Err(err) = ocx.eq(
+            &ObligationCause::misc(instantiated_ty.span, body_id),
+            param_env,
+            opaque_ty,
+            definition_ty,
+        ) {
+            infcx
+                .err_ctxt()
+                .report_mismatched_types(
+                    &ObligationCause::misc(instantiated_ty.span, body_id),
+                    opaque_ty,
+                    definition_ty,
+                    err,
+                )
+                .emit();
         }
 
-        fulfillment_cx.register_predicate_obligation(
-            &infcx,
-            Obligation::misc(instantiated_ty.span, body_id, param_env, predicate),
-        );
+        ocx.register_obligation(Obligation::misc(
+            infcx.tcx,
+            instantiated_ty.span,
+            body_id,
+            param_env,
+            predicate,
+        ));
 
         // Check that all obligations are satisfied by the implementation's
         // version.
-        let errors = fulfillment_cx.select_all_or_error(&infcx);
+        let errors = ocx.select_all_or_error();
 
         // This is still required for many(half of the tests in ui/type-alias-impl-trait)
         // tests to pass
@@ -302,8 +323,8 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
         if errors.is_empty() {
             definition_ty
         } else {
-            infcx.err_ctxt().report_fulfillment_errors(&errors, None, false);
-            self.tcx.ty_error()
+            let reported = infcx.err_ctxt().report_fulfillment_errors(&errors, None);
+            self.tcx.ty_error_with_guaranteed(reported)
         }
     }
 }
diff --git a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
index 1e6798eee..167f66460 100644
--- a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
+++ b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use crate::constraints::ConstraintSccIndex;
 use crate::RegionInferenceContext;
 use itertools::Itertools;
diff --git a/compiler/rustc_borrowck/src/region_infer/values.rs b/compiler/rustc_borrowck/src/region_infer/values.rs
index de20a4bb4..7498ddccf 100644
--- a/compiler/rustc_borrowck/src/region_infer/values.rs
+++ b/compiler/rustc_borrowck/src/region_infer/values.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_index::bit_set::SparseBitMatrix;
 use rustc_index::interval::IntervalSet;
diff --git a/compiler/rustc_borrowck/src/renumber.rs b/compiler/rustc_borrowck/src/renumber.rs
index f30237690..084754830 100644
--- a/compiler/rustc_borrowck/src/renumber.rs
+++ b/compiler/rustc_borrowck/src/renumber.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_middle::mir::visit::{MutVisitor, TyContext};
diff --git a/compiler/rustc_borrowck/src/session_diagnostics.rs b/compiler/rustc_borrowck/src/session_diagnostics.rs
index cff3089c3..577332c07 100644
--- a/compiler/rustc_borrowck/src/session_diagnostics.rs
+++ b/compiler/rustc_borrowck/src/session_diagnostics.rs
@@ -49,7 +49,7 @@ pub(crate) struct GenericDoesNotLiveLongEnough {
 #[derive(LintDiagnostic)]
 #[diag(borrowck_var_does_not_need_mut)]
 pub(crate) struct VarNeedNotMut {
-    #[suggestion_short(applicability = "machine-applicable", code = "")]
+    #[suggestion(style = "short", applicability = "machine-applicable", code = "")]
     pub span: Span,
 }
 #[derive(Diagnostic)]
@@ -148,3 +148,95 @@ pub(crate) enum RequireStaticErr {
         multi_span: MultiSpan,
     },
 }
+
+#[derive(Subdiagnostic)]
+pub(crate) enum CaptureVarPathUseCause {
+    #[label(borrowck_borrow_due_to_use_generator)]
+    BorrowInGenerator {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_use_due_to_use_generator)]
+    UseInGenerator {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_assign_due_to_use_generator)]
+    AssignInGenerator {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_assign_part_due_to_use_generator)]
+    AssignPartInGenerator {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_borrow_due_to_use_closure)]
+    BorrowInClosure {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_use_due_to_use_closure)]
+    UseInClosure {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_assign_due_to_use_closure)]
+    AssignInClosure {
+        #[primary_span]
+        path_span: Span,
+    },
+    #[label(borrowck_assign_part_due_to_use_closure)]
+    AssignPartInClosure {
+        #[primary_span]
+        path_span: Span,
+    },
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum CaptureVarKind {
+    #[label(borrowck_capture_immute)]
+    Immute {
+        #[primary_span]
+        kind_span: Span,
+    },
+    #[label(borrowck_capture_mut)]
+    Mut {
+        #[primary_span]
+        kind_span: Span,
+    },
+    #[label(borrowck_capture_move)]
+    Move {
+        #[primary_span]
+        kind_span: Span,
+    },
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum CaptureVarCause {
+    #[label(borrowck_var_borrow_by_use_place_in_generator)]
+    BorrowUsePlaceGenerator {
+        place: String,
+        #[primary_span]
+        var_span: Span,
+    },
+    #[label(borrowck_var_borrow_by_use_place_in_closure)]
+    BorrowUsePlaceClosure {
+        place: String,
+        #[primary_span]
+        var_span: Span,
+    },
+}
+
+#[derive(Diagnostic)]
+#[diag(borrowck_cannot_move_when_borrowed, code = "E0505")]
+pub(crate) struct MoveBorrow<'a> {
+    pub place: &'a str,
+    pub borrow_place: &'a str,
+    pub value_place: &'a str,
+    #[primary_span]
+    #[label(move_label)]
+    pub span: Span,
+    #[label]
+    pub borrow_span: Span,
+}
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index a581726a1..3617bf58b 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -88,12 +88,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         category: ConstraintCategory<'tcx>,
     ) {
         self.prove_predicate(
-            ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
+            ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::Trait(ty::TraitPredicate {
                 trait_ref,
                 constness: ty::BoundConstness::NotConst,
                 polarity: ty::ImplPolarity::Positive,
-            }))
-            .to_predicate(self.tcx()),
+            }))),
             locations,
             category,
         );
@@ -122,14 +121,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
     pub(super) fn prove_predicates(
         &mut self,
-        predicates: impl IntoIterator<Item = impl ToPredicate<'tcx>>,
+        predicates: impl IntoIterator<Item = impl ToPredicate<'tcx> + std::fmt::Debug>,
         locations: Locations,
         category: ConstraintCategory<'tcx>,
     ) {
         for predicate in predicates {
-            let predicate = predicate.to_predicate(self.tcx());
-            debug!("prove_predicates(predicate={:?}, locations={:?})", predicate, locations,);
-
             self.prove_predicate(predicate, locations, category);
         }
     }
@@ -137,11 +133,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     pub(super) fn prove_predicate(
         &mut self,
-        predicate: ty::Predicate<'tcx>,
+        predicate: impl ToPredicate<'tcx> + std::fmt::Debug,
         locations: Locations,
         category: ConstraintCategory<'tcx>,
     ) {
         let param_env = self.param_env;
+        let predicate = predicate.to_predicate(self.tcx());
         self.fully_perform_op(
             locations,
             category,
diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
index d5bfc2f52..ce7f857e2 100644
--- a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
+++ b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -1,10 +1,10 @@
-use rustc_infer::infer::canonical::QueryOutlivesConstraint;
+use rustc_hir::def_id::DefId;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_infer::infer::outlives::obligations::{TypeOutlives, TypeOutlivesDelegate};
 use rustc_infer::infer::region_constraints::{GenericKind, VerifyBound};
 use rustc_infer::infer::{self, InferCtxt, SubregionOrigin};
-use rustc_middle::mir::ConstraintCategory;
+use rustc_middle::mir::{ClosureOutlivesSubject, ClosureRegionRequirements, ConstraintCategory};
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, TyCtxt};
@@ -38,6 +38,7 @@ pub(crate) struct ConstraintConversion<'a, 'tcx> {
     locations: Locations,
     span: Span,
     category: ConstraintCategory<'tcx>,
+    from_closure: bool,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
 }
 
@@ -64,6 +65,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             span,
             category,
             constraints,
+            from_closure: false,
         }
     }
 
@@ -81,12 +83,62 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         }
         self.constraints.member_constraints = tmp;
 
-        for query_constraint in outlives {
-            self.convert(query_constraint);
+        for (predicate, constraint_category) in outlives {
+            // At the moment, we never generate any "higher-ranked"
+            // region constraints like `for<'a> 'a: 'b`. At some point
+            // when we move to universes, we will, and this assertion
+            // will start to fail.
+            let predicate = predicate.no_bound_vars().unwrap_or_else(|| {
+                bug!("query_constraint {:?} contained bound vars", predicate,);
+            });
+
+            self.convert(predicate, *constraint_category);
         }
     }
 
-    fn convert(&mut self, query_constraint: &QueryOutlivesConstraint<'tcx>) {
+    /// Given an instance of the closure type, this method instantiates the "extra" requirements
+    /// that we computed for the closure. This has the effect of adding new outlives obligations
+    /// to existing region variables in `closure_substs`.
+    #[instrument(skip(self), level = "debug")]
+    pub fn apply_closure_requirements(
+        &mut self,
+        closure_requirements: &ClosureRegionRequirements<'tcx>,
+        closure_def_id: DefId,
+        closure_substs: ty::SubstsRef<'tcx>,
+    ) {
+        // Extract the values of the free regions in `closure_substs`
+        // into a vector.  These are the regions that we will be
+        // relating to one another.
+        let closure_mapping = &UniversalRegions::closure_mapping(
+            self.tcx,
+            closure_substs,
+            closure_requirements.num_external_vids,
+            closure_def_id.expect_local(),
+        );
+        debug!(?closure_mapping);
+
+        // Create the predicates.
+        let backup = (self.category, self.span, self.from_closure);
+        self.from_closure = true;
+        for outlives_requirement in &closure_requirements.outlives_requirements {
+            let outlived_region = closure_mapping[outlives_requirement.outlived_free_region];
+            let subject = match outlives_requirement.subject {
+                ClosureOutlivesSubject::Region(re) => closure_mapping[re].into(),
+                ClosureOutlivesSubject::Ty(ty) => ty.into(),
+            };
+
+            self.category = outlives_requirement.category;
+            self.span = outlives_requirement.blame_span;
+            self.convert(ty::OutlivesPredicate(subject, outlived_region), self.category);
+        }
+        (self.category, self.span, self.from_closure) = backup;
+    }
+
+    fn convert(
+        &mut self,
+        predicate: ty::OutlivesPredicate<ty::GenericArg<'tcx>, ty::Region<'tcx>>,
+        constraint_category: ConstraintCategory<'tcx>,
+    ) {
         debug!("generate: constraints at: {:#?}", self.locations);
 
         // Extract out various useful fields we'll need below.
@@ -94,17 +146,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             tcx, region_bound_pairs, implicit_region_bound, param_env, ..
         } = *self;
 
-        // At the moment, we never generate any "higher-ranked"
-        // region constraints like `for<'a> 'a: 'b`. At some point
-        // when we move to universes, we will, and this assertion
-        // will start to fail.
-        let ty::OutlivesPredicate(k1, r2) =
-            query_constraint.0.no_bound_vars().unwrap_or_else(|| {
-                bug!("query_constraint {:?} contained bound vars", query_constraint,);
-            });
-
-        let constraint_category = query_constraint.1;
-
+        let ty::OutlivesPredicate(k1, r2) = predicate;
         match k1.unpack() {
             GenericArgKind::Lifetime(r1) => {
                 let r1_vid = self.to_region_vid(r1);
@@ -127,10 +169,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
                 .type_must_outlive(origin, t1, r2, constraint_category);
             }
 
-            GenericArgKind::Const(_) => {
-                // Consts cannot outlive one another, so we
-                // don't need to handle any relations here.
-            }
+            GenericArgKind::Const(_) => unreachable!(),
         }
     }
 
@@ -160,7 +199,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         verify_bound: VerifyBound<'tcx>,
     ) -> TypeTest<'tcx> {
         let lower_bound = self.to_region_vid(region);
-        TypeTest { generic_kind, lower_bound, locations: self.locations, verify_bound }
+        TypeTest { generic_kind, lower_bound, span: self.span, verify_bound }
     }
 
     fn to_region_vid(&mut self, r: ty::Region<'tcx>) -> ty::RegionVid {
@@ -188,6 +227,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             sub,
             sup,
             variance_info: ty::VarianceDiagInfo::default(),
+            from_closure: self.from_closure,
         });
     }
 
diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
index 029095926..14cfc3613 100644
--- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
+++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
@@ -247,12 +247,13 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
                     .and(type_op::normalize::Normalize::new(ty))
                     .fully_perform(self.infcx)
                     .unwrap_or_else(|_| {
-                        self.infcx
+                        let reported = self
+                            .infcx
                             .tcx
                             .sess
                             .delay_span_bug(span, &format!("failed to normalize {:?}", ty));
                         TypeOpOutput {
-                            output: self.infcx.tcx.ty_error(),
+                            output: self.infcx.tcx.ty_error_with_guaranteed(reported),
                             constraints: None,
                             error_info: None,
                         }
diff --git a/compiler/rustc_borrowck/src/type_check/input_output.rs b/compiler/rustc_borrowck/src/type_check/input_output.rs
index a66ddd27d..62c6f9581 100644
--- a/compiler/rustc_borrowck/src/type_check/input_output.rs
+++ b/compiler/rustc_borrowck/src/type_check/input_output.rs
@@ -42,8 +42,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             user_provided_sig = None;
         } else {
             let typeck_results = self.tcx().typeck(mir_def_id);
-            user_provided_sig = typeck_results.user_provided_sigs.get(&mir_def_id.to_def_id()).map(
-                |user_provided_poly_sig| {
+            user_provided_sig =
+                typeck_results.user_provided_sigs.get(&mir_def_id).map(|user_provided_poly_sig| {
                     // Instantiate the canonicalized variables from
                     // user-provided signature (e.g., the `_` in the code
                     // above) with fresh variables.
@@ -60,8 +60,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         LateBoundRegionConversionTime::FnCall,
                         poly_sig,
                     )
-                },
-            );
+                });
         }
 
         debug!(?normalized_input_tys, ?body.local_decls);
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs b/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs
index bc76a465e..b344ab46a 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/polonius.rs
@@ -121,8 +121,8 @@ pub(super) fn populate_access_facts<'a, 'tcx>(
     }
 }
 
-// For every potentially drop()-touched region `region` in `local`'s type
-// (`kind`), emit a Polonius `use_of_var_derefs_origin(local, origin)` fact.
+/// For every potentially drop()-touched region `region` in `local`'s type
+/// (`kind`), emit a Polonius `use_of_var_derefs_origin(local, origin)` fact.
 pub(super) fn add_drop_of_var_derefs_origin<'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     local: Local,
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 3c1c3ab45..6d4ec6b72 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! This pass type-checks the MIR to ensure it is not broken.
 
 use std::rc::Rc;
@@ -27,12 +29,11 @@ use rustc_middle::mir::AssertKind;
 use rustc_middle::mir::*;
 use rustc_middle::ty::adjustment::PointerCast;
 use rustc_middle::ty::cast::CastTy;
-use rustc_middle::ty::subst::{GenericArgKind, SubstsRef, UserSubsts};
+use rustc_middle::ty::subst::{SubstsRef, UserSubsts};
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{
     self, Binder, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, Dynamic,
-    OpaqueHiddenType, OpaqueTypeKey, RegionVid, ToPredicate, Ty, TyCtxt, UserType,
-    UserTypeAnnotationIndex,
+    OpaqueHiddenType, OpaqueTypeKey, RegionVid, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,
 };
 use rustc_span::def_id::CRATE_DEF_ID;
 use rustc_span::{Span, DUMMY_SP};
@@ -61,7 +62,7 @@ use crate::{
     region_infer::values::{
         LivenessValues, PlaceholderIndex, PlaceholderIndices, RegionValueElements,
     },
-    region_infer::{ClosureRegionRequirementsExt, TypeTest},
+    region_infer::TypeTest,
     type_check::free_region_relations::{CreateResult, UniversalRegionRelations},
     universal_regions::{DefiningTy, UniversalRegions},
     Upvar,
@@ -144,7 +145,6 @@ pub(crate) fn type_check<'mir, 'tcx>(
         liveness_constraints: LivenessValues::new(elements.clone()),
         outlives_constraints: OutlivesConstraintSet::default(),
         member_constraints: MemberConstraintSet::default(),
-        closure_bounds_mapping: Default::default(),
         type_tests: Vec::default(),
         universe_causes: FxHashMap::default(),
     };
@@ -234,11 +234,11 @@ pub(crate) fn type_check<'mir, 'tcx>(
             let mut hidden_type = infcx.resolve_vars_if_possible(decl.hidden_type);
             trace!("finalized opaque type {:?} to {:#?}", opaque_type_key, hidden_type.ty.kind());
             if hidden_type.has_non_region_infer() {
-                infcx.tcx.sess.delay_span_bug(
+                let reported = infcx.tcx.sess.delay_span_bug(
                     decl.hidden_type.span,
                     &format!("could not resolve {:#?}", hidden_type.ty.kind()),
                 );
-                hidden_type.ty = infcx.tcx.ty_error();
+                hidden_type.ty = infcx.tcx.ty_error_with_guaranteed(reported);
             }
 
             (opaque_type_key, (hidden_type, decl.origin))
@@ -547,10 +547,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
 
         if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context {
             let tcx = self.tcx();
-            let trait_ref = ty::TraitRef {
-                def_id: tcx.require_lang_item(LangItem::Copy, Some(self.last_span)),
-                substs: tcx.mk_substs_trait(place_ty.ty, &[]),
-            };
+            let trait_ref = tcx.at(self.last_span).mk_trait_ref(LangItem::Copy, [place_ty.ty]);
 
             // To have a `Copy` operand, the type `T` of the
             // value must be `Copy`. Note that we prove that `T: Copy`,
@@ -584,8 +581,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         // modify their locations.
         let all_facts = &mut None;
         let mut constraints = Default::default();
-        let mut type_tests = Default::default();
-        let mut closure_bounds = Default::default();
         let mut liveness_constraints =
             LivenessValues::new(Rc::new(RegionValueElements::new(&promoted_body)));
         // Don't try to add borrow_region facts for the promoted MIR
@@ -596,11 +591,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 &mut this.cx.borrowck_context.constraints.outlives_constraints,
                 &mut constraints,
             );
-            mem::swap(&mut this.cx.borrowck_context.constraints.type_tests, &mut type_tests);
-            mem::swap(
-                &mut this.cx.borrowck_context.constraints.closure_bounds_mapping,
-                &mut closure_bounds,
-            );
             mem::swap(
                 &mut this.cx.borrowck_context.constraints.liveness_constraints,
                 &mut liveness_constraints,
@@ -621,13 +611,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         swap_constraints(self);
 
         let locations = location.to_locations();
-
-        // Use location of promoted const in collected constraints
-        for type_test in type_tests.iter() {
-            let mut type_test = type_test.clone();
-            type_test.locations = locations;
-            self.cx.borrowck_context.constraints.type_tests.push(type_test)
-        }
         for constraint in constraints.outlives().iter() {
             let mut constraint = constraint.clone();
             constraint.locations = locations;
@@ -653,18 +636,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                     .add_element(region, location);
             }
         }
-
-        if !closure_bounds.is_empty() {
-            let combined_bounds_mapping =
-                closure_bounds.into_iter().flat_map(|(_, value)| value).collect();
-            let existing = self
-                .cx
-                .borrowck_context
-                .constraints
-                .closure_bounds_mapping
-                .insert(location, combined_bounds_mapping);
-            assert!(existing.is_none(), "Multiple promoteds/closures at the same location.");
-        }
     }
 
     fn sanitize_projection(
@@ -941,9 +912,6 @@ pub(crate) struct MirTypeckRegionConstraints<'tcx> {
 
     pub(crate) member_constraints: MemberConstraintSet<'tcx, RegionVid>,
 
-    pub(crate) closure_bounds_mapping:
-        FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory<'tcx>, Span)>>,
-
     pub(crate) universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
 
     pub(crate) type_tests: Vec<TypeTest<'tcx>>,
@@ -1097,8 +1065,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     }
 
                     self.prove_predicate(
-                        ty::Binder::dummy(ty::PredicateKind::WellFormed(inferred_ty.into()))
-                            .to_predicate(self.tcx()),
+                        ty::Binder::dummy(ty::PredicateKind::WellFormed(inferred_ty.into())),
                         Locations::All(span),
                         ConstraintCategory::TypeAnnotation,
                     );
@@ -1222,8 +1189,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) {
         let tcx = self.tcx();
         debug!("stmt kind: {:?}", stmt.kind);
-        match stmt.kind {
-            StatementKind::Assign(box (ref place, ref rv)) => {
+        match &stmt.kind {
+            StatementKind::Assign(box (place, rv)) => {
                 // Assignments to temporaries are not "interesting";
                 // they are not caused by the user, but rather artifacts
                 // of lowering. Assignments to other sorts of places *are* interesting
@@ -1303,10 +1270,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
                 self.check_rvalue(body, rv, location);
                 if !self.unsized_feature_enabled() {
-                    let trait_ref = ty::TraitRef {
-                        def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
-                        substs: tcx.mk_substs_trait(place_ty, &[]),
-                    };
+                    let trait_ref =
+                        tcx.at(self.last_span).mk_trait_ref(LangItem::Sized, [place_ty]);
                     self.prove_trait_ref(
                         trait_ref,
                         location.to_locations(),
@@ -1314,11 +1279,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            StatementKind::AscribeUserType(box (ref place, ref projection), variance) => {
+            StatementKind::AscribeUserType(box (place, projection), variance) => {
                 let place_ty = place.ty(body, tcx).ty;
                 if let Err(terr) = self.relate_type_and_user_type(
                     place_ty,
-                    variance,
+                    *variance,
                     projection,
                     Locations::All(stmt.source_info.span),
                     ConstraintCategory::TypeAnnotation,
@@ -1335,7 +1300,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            StatementKind::Intrinsic(box ref kind) => match kind {
+            StatementKind::Intrinsic(box kind) => match kind {
                 NonDivergingIntrinsic::Assume(op) => self.check_operand(op, location),
                 NonDivergingIntrinsic::CopyNonOverlapping(..) => span_bug!(
                     stmt.source_info.span,
@@ -1363,7 +1328,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     ) {
         let tcx = self.tcx();
         debug!("terminator kind: {:?}", term.kind);
-        match term.kind {
+        match &term.kind {
             TerminatorKind::Goto { .. }
             | TerminatorKind::Resume
             | TerminatorKind::Abort
@@ -1377,7 +1342,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 // no checks needed for these
             }
 
-            TerminatorKind::DropAndReplace { ref place, ref value, target: _, unwind: _ } => {
+            TerminatorKind::DropAndReplace { place, value, target: _, unwind: _ } => {
                 let place_ty = place.ty(body, tcx).ty;
                 let rv_ty = value.ty(body, tcx);
 
@@ -1395,13 +1360,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            TerminatorKind::SwitchInt { ref discr, switch_ty, .. } => {
+            TerminatorKind::SwitchInt { discr, switch_ty, .. } => {
                 self.check_operand(discr, term_location);
 
                 let discr_ty = discr.ty(body, tcx);
                 if let Err(terr) = self.sub_types(
                     discr_ty,
-                    switch_ty,
+                    *switch_ty,
                     term_location.to_locations(),
                     ConstraintCategory::Assignment,
                 ) {
@@ -1419,14 +1384,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 }
                 // FIXME: check the values
             }
-            TerminatorKind::Call {
-                ref func,
-                ref args,
-                ref destination,
-                from_hir_call,
-                target,
-                ..
-            } => {
+            TerminatorKind::Call { func, args, destination, from_hir_call, target, .. } => {
                 self.check_operand(func, term_location);
                 for arg in args {
                     self.check_operand(arg, term_location);
@@ -1466,7 +1424,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     ConstraintCategory::Boring,
                 );
                 let sig = self.normalize(sig, term_location);
-                self.check_call_dest(body, term, &sig, *destination, target, term_location);
+                self.check_call_dest(body, term, &sig, *destination, *target, term_location);
 
                 // The ordinary liveness rules will ensure that all
                 // regions in the type of the callee are live here. We
@@ -1484,9 +1442,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         .add_element(region_vid, term_location);
                 }
 
-                self.check_call_inputs(body, term, &sig, args, term_location, from_hir_call);
+                self.check_call_inputs(body, term, &sig, args, term_location, *from_hir_call);
             }
-            TerminatorKind::Assert { ref cond, ref msg, .. } => {
+            TerminatorKind::Assert { cond, msg, .. } => {
                 self.check_operand(cond, term_location);
 
                 let cond_ty = cond.ty(body, tcx);
@@ -1494,7 +1452,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty);
                 }
 
-                if let AssertKind::BoundsCheck { ref len, ref index } = *msg {
+                if let AssertKind::BoundsCheck { len, index } = msg {
                     if len.ty(body, tcx) != tcx.types.usize {
                         span_mirbug!(self, len, "bounds-check length non-usize {:?}", len)
                     }
@@ -1503,7 +1461,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     }
                 }
             }
-            TerminatorKind::Yield { ref value, .. } => {
+            TerminatorKind::Yield { value, .. } => {
                 self.check_operand(value, term_location);
 
                 let value_ty = value.ty(body, tcx);
@@ -1594,10 +1552,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 }
             }
             None => {
-                if !self
-                    .tcx()
-                    .conservative_is_privately_uninhabited(self.param_env.and(sig.output()))
-                {
+                if !sig.output().is_privately_uninhabited(self.tcx(), self.param_env) {
                     span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
                 }
             }
@@ -1873,6 +1828,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     #[instrument(skip(self, body), level = "debug")]
     fn check_rvalue(&mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
         let tcx = self.tcx();
+        let span = body.source_info(location).span;
 
         match rvalue {
             Rvalue::Aggregate(ak, ops) => {
@@ -1896,12 +1852,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         }
                         Operand::Move(place) => {
                             // Make sure that repeated elements implement `Copy`.
-                            let span = body.source_info(location).span;
                             let ty = place.ty(body, tcx).ty;
-                            let trait_ref = ty::TraitRef::new(
-                                tcx.require_lang_item(LangItem::Copy, Some(span)),
-                                tcx.mk_substs_trait(ty, &[]),
-                            );
+                            let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Copy, [ty]);
 
                             self.prove_trait_ref(
                                 trait_ref,
@@ -1914,10 +1866,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             }
 
             &Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, ty) => {
-                let trait_ref = ty::TraitRef {
-                    def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
-                    substs: tcx.mk_substs_trait(ty, &[]),
-                };
+                let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Sized, [ty]);
 
                 self.prove_trait_ref(
                     trait_ref,
@@ -1929,10 +1878,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             Rvalue::ShallowInitBox(operand, ty) => {
                 self.check_operand(operand, location);
 
-                let trait_ref = ty::TraitRef {
-                    def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
-                    substs: tcx.mk_substs_trait(*ty, &[]),
-                };
+                let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Sized, [*ty]);
 
                 self.prove_trait_ref(
                     trait_ref,
@@ -2029,11 +1975,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
                     CastKind::Pointer(PointerCast::Unsize) => {
                         let &ty = ty;
-                        let trait_ref = ty::TraitRef {
-                            def_id: tcx
-                                .require_lang_item(LangItem::CoerceUnsized, Some(self.last_span)),
-                            substs: tcx.mk_substs_trait(op.ty(body, tcx), &[ty.into()]),
-                        };
+                        let trait_ref = tcx
+                            .at(span)
+                            .mk_trait_ref(LangItem::CoerceUnsized, [op.ty(body, tcx), ty]);
 
                         self.prove_trait_ref(
                             trait_ref,
@@ -2062,8 +2006,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         );
 
                         let outlives_predicate =
-                            tcx.mk_predicate(Binder::dummy(ty::PredicateKind::TypeOutlives(
-                                ty::OutlivesPredicate(self_ty, *region),
+                            tcx.mk_predicate(Binder::dummy(ty::PredicateKind::Clause(
+                                ty::Clause::TypeOutlives(ty::OutlivesPredicate(self_ty, *region)),
                             )));
                         self.prove_predicate(
                             outlives_predicate,
@@ -2562,6 +2506,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                                 span: location.to_locations().span(body),
                                 category,
                                 variance_info: ty::VarianceDiagInfo::default(),
+                                from_closure: false,
                             });
 
                             match mutbl {
@@ -2636,7 +2581,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             }
 
             // For closures, we have some **extra requirements** we
-            //
             // have to check. In particular, in their upvars and
             // signatures, closures often reference various regions
             // from the surrounding function -- we call those the
@@ -2679,62 +2623,22 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         substs: SubstsRef<'tcx>,
         location: Location,
     ) -> ty::InstantiatedPredicates<'tcx> {
-        if let Some(ref closure_region_requirements) = tcx.mir_borrowck(def_id).closure_requirements
-        {
-            let closure_constraints = QueryRegionConstraints {
-                outlives: closure_region_requirements.apply_requirements(
-                    tcx,
-                    def_id.to_def_id(),
-                    substs,
-                ),
-
-                // Presently, closures never propagate member
-                // constraints to their parents -- they are enforced
-                // locally.  This is largely a non-issue as member
-                // constraints only come from `-> impl Trait` and
-                // friends which don't appear (thus far...) in
-                // closures.
-                member_constraints: vec![],
-            };
-
-            let bounds_mapping = closure_constraints
-                .outlives
-                .iter()
-                .enumerate()
-                .filter_map(|(idx, constraint)| {
-                    let ty::OutlivesPredicate(k1, r2) =
-                        constraint.0.no_bound_vars().unwrap_or_else(|| {
-                            bug!("query_constraint {:?} contained bound vars", constraint,);
-                        });
-
-                    match k1.unpack() {
-                        GenericArgKind::Lifetime(r1) => {
-                            // constraint is r1: r2
-                            let r1_vid = self.borrowck_context.universal_regions.to_region_vid(r1);
-                            let r2_vid = self.borrowck_context.universal_regions.to_region_vid(r2);
-                            let outlives_requirements =
-                                &closure_region_requirements.outlives_requirements[idx];
-                            Some((
-                                (r1_vid, r2_vid),
-                                (outlives_requirements.category, outlives_requirements.blame_span),
-                            ))
-                        }
-                        GenericArgKind::Type(_) | GenericArgKind::Const(_) => None,
-                    }
-                })
-                .collect();
-
-            let existing = self
-                .borrowck_context
-                .constraints
-                .closure_bounds_mapping
-                .insert(location, bounds_mapping);
-            assert!(existing.is_none(), "Multiple closures at the same location.");
-
-            self.push_region_constraints(
+        if let Some(closure_requirements) = &tcx.mir_borrowck(def_id).closure_requirements {
+            constraint_conversion::ConstraintConversion::new(
+                self.infcx,
+                self.borrowck_context.universal_regions,
+                self.region_bound_pairs,
+                self.implicit_region_bound,
+                self.param_env,
                 location.to_locations(),
-                ConstraintCategory::ClosureBounds,
-                &closure_constraints,
+                DUMMY_SP,                   // irrelevant; will be overrided.
+                ConstraintCategory::Boring, // same as above.
+                &mut self.borrowck_context.constraints,
+            )
+            .apply_closure_requirements(
+                &closure_requirements,
+                def_id.to_def_id(),
+                substs,
             );
         }
 
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index 4f2dc263b..b2702eafd 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -2,9 +2,8 @@ use rustc_infer::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRe
 use rustc_infer::infer::NllRegionVariableOrigin;
 use rustc_infer::traits::PredicateObligations;
 use rustc_middle::mir::ConstraintCategory;
-use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::TypeRelation;
-use rustc_middle::ty::{self, Const, Ty};
+use rustc_middle::ty::{self, Ty};
 use rustc_span::Span;
 use rustc_trait_selection::traits::query::Fallible;
 
@@ -136,17 +135,11 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
                 span: self.locations.span(self.type_checker.body),
                 category: self.category,
                 variance_info: info,
+                from_closure: false,
             },
         );
     }
 
-    // We don't have to worry about the equality of consts during borrow checking
-    // as consts always have a static lifetime.
-    // FIXME(oli-obk): is this really true? We can at least have HKL and with
-    // inline consts we may have further lifetimes that may be unsound to treat as
-    // 'static.
-    fn const_equate(&mut self, _a: Const<'tcx>, _b: Const<'tcx>) {}
-
     fn normalization() -> NormalizationStrategy {
         NormalizationStrategy::Eager
     }
@@ -155,10 +148,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
         true
     }
 
-    fn register_opaque_type_obligations(
-        &mut self,
-        obligations: PredicateObligations<'tcx>,
-    ) -> Result<(), TypeError<'tcx>> {
+    fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
         self.type_checker
             .fully_perform_op(
                 self.locations,
@@ -171,6 +161,5 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
                 },
             )
             .unwrap();
-        Ok(())
     }
 }
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 2beb5e0ab..a4a0c5b90 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -22,7 +22,9 @@ use rustc_hir::{BodyOwnerKind, HirId};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{self, InlineConstSubsts, InlineConstSubstsParts, RegionVid, Ty, TyCtxt};
+use rustc_middle::ty::{
+    self, DefIdTree, InlineConstSubsts, InlineConstSubstsParts, RegionVid, Ty, TyCtxt,
+};
 use rustc_middle::ty::{InternalSubsts, SubstsRef};
 use std::iter;
 
@@ -241,7 +243,7 @@ impl<'tcx> UniversalRegions<'tcx> {
         tcx: TyCtxt<'tcx>,
         closure_substs: SubstsRef<'tcx>,
         expected_num_vars: usize,
-        typeck_root_def_id: DefId,
+        closure_def_id: LocalDefId,
     ) -> IndexVec<RegionVid, ty::Region<'tcx>> {
         let mut region_mapping = IndexVec::with_capacity(expected_num_vars);
         region_mapping.push(tcx.lifetimes.re_static);
@@ -249,7 +251,7 @@ impl<'tcx> UniversalRegions<'tcx> {
             region_mapping.push(fr);
         });
 
-        for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
+        for_each_late_bound_region_in_recursive_scope(tcx, tcx.local_parent(closure_def_id), |r| {
             region_mapping.push(r);
         });
 
@@ -339,9 +341,8 @@ impl<'tcx> UniversalRegions<'tcx> {
                 // tests, and the resulting print-outs include def-ids
                 // and other things that are not stable across tests!
                 // So we just include the region-vid. Annoying.
-                let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
-                for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
-                    err.note(&format!("late-bound region is {:?}", self.to_region_vid(r),));
+                for_each_late_bound_region_in_recursive_scope(tcx, def_id.expect_local(), |r| {
+                    err.note(&format!("late-bound region is {:?}", self.to_region_vid(r)));
                 });
             }
             DefiningTy::Generator(def_id, substs, _) => {
@@ -354,9 +355,8 @@ impl<'tcx> UniversalRegions<'tcx> {
                 // FIXME: As above, we'd like to print out the region
                 // `r` but doing so is not stable across architectures
                 // and so forth.
-                let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
-                for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
-                    err.note(&format!("late-bound region is {:?}", self.to_region_vid(r),));
+                for_each_late_bound_region_in_recursive_scope(tcx, def_id.expect_local(), |r| {
+                    err.note(&format!("late-bound region is {:?}", self.to_region_vid(r)));
                 });
             }
             DefiningTy::FnDef(def_id, substs) => {
@@ -421,13 +421,24 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             first_extern_index
         } else {
             // If this is a closure, generator, or inline-const, then the late-bound regions from the enclosing
-            // function are actually external regions to us. For example, here, 'a is not local
+            // function/closures are actually external regions to us. For example, here, 'a is not local
             // to the closure c (although it is local to the fn foo):
             // fn foo<'a>() {
             //     let c = || { let x: &'a u32 = ...; }
             // }
-            self.infcx
-                .replace_late_bound_regions_with_nll_infer_vars(self.mir_def.did, &mut indices);
+            for_each_late_bound_region_in_recursive_scope(
+                self.infcx.tcx,
+                self.infcx.tcx.local_parent(self.mir_def.did),
+                |r| {
+                    debug!(?r);
+                    if !indices.indices.contains_key(&r) {
+                        let region_vid = self.infcx.next_nll_region_var(FR);
+                        debug!(?region_vid);
+                        indices.insert_late_bound_region(r, region_vid.to_region_vid());
+                    }
+                },
+            );
+
             // Any regions created during the execution of `defining_ty` or during the above
             // late-bound region replacement are all considered 'extern' regions
             self.infcx.num_region_vars()
@@ -444,12 +455,16 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             bound_inputs_and_output,
             &mut indices,
         );
-        // Converse of above, if this is a function then the late-bound regions declared on its
-        // signature are local to the fn.
-        if self.mir_def.did.to_def_id() == typeck_root_def_id {
-            self.infcx
-                .replace_late_bound_regions_with_nll_infer_vars(self.mir_def.did, &mut indices);
-        }
+        // Converse of above, if this is a function/closure then the late-bound regions declared on its
+        // signature are local.
+        for_each_late_bound_region_in_item(self.infcx.tcx, self.mir_def.did, |r| {
+            debug!(?r);
+            if !indices.indices.contains_key(&r) {
+                let region_vid = self.infcx.next_nll_region_var(FR);
+                debug!(?region_vid);
+                indices.insert_late_bound_region(r, region_vid.to_region_vid());
+            }
+        });
 
         let (unnormalized_output_ty, mut unnormalized_input_tys) =
             inputs_and_output.split_last().unwrap();
@@ -572,9 +587,9 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
         let typeck_root_def_id = tcx.typeck_root_def_id(self.mir_def.did.to_def_id());
         let identity_substs = InternalSubsts::identity_for_item(tcx, typeck_root_def_id);
         let fr_substs = match defining_ty {
-            DefiningTy::Closure(_, ref substs)
-            | DefiningTy::Generator(_, ref substs, _)
-            | DefiningTy::InlineConst(_, ref substs) => {
+            DefiningTy::Closure(_, substs)
+            | DefiningTy::Generator(_, substs, _)
+            | DefiningTy::InlineConst(_, substs) => {
                 // In the case of closures, we rely on the fact that
                 // the first N elements in the ClosureSubsts are
                 // inherited from the `typeck_root_def_id`.
@@ -692,7 +707,13 @@ trait InferCtxtExt<'tcx> {
     where
         T: TypeFoldable<'tcx>;
 
-    fn replace_late_bound_regions_with_nll_infer_vars(
+    fn replace_late_bound_regions_with_nll_infer_vars_in_recursive_scope(
+        &self,
+        mir_def_id: LocalDefId,
+        indices: &mut UniversalRegionIndices<'tcx>,
+    );
+
+    fn replace_late_bound_regions_with_nll_infer_vars_in_item(
         &self,
         mir_def_id: LocalDefId,
         indices: &mut UniversalRegionIndices<'tcx>,
@@ -746,13 +767,28 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
     /// set of late-bound regions and checks for any that we have not yet seen, adding them to the
     /// inputs vector.
     #[instrument(skip(self, indices))]
-    fn replace_late_bound_regions_with_nll_infer_vars(
+    fn replace_late_bound_regions_with_nll_infer_vars_in_recursive_scope(
+        &self,
+        mir_def_id: LocalDefId,
+        indices: &mut UniversalRegionIndices<'tcx>,
+    ) {
+        for_each_late_bound_region_in_recursive_scope(self.tcx, mir_def_id, |r| {
+            debug!(?r);
+            if !indices.indices.contains_key(&r) {
+                let region_vid = self.next_nll_region_var(FR);
+                debug!(?region_vid);
+                indices.insert_late_bound_region(r, region_vid.to_region_vid());
+            }
+        });
+    }
+
+    #[instrument(skip(self, indices))]
+    fn replace_late_bound_regions_with_nll_infer_vars_in_item(
         &self,
         mir_def_id: LocalDefId,
         indices: &mut UniversalRegionIndices<'tcx>,
     ) {
-        let typeck_root_def_id = self.tcx.typeck_root_def_id(mir_def_id.to_def_id());
-        for_each_late_bound_region_defined_on(self.tcx, typeck_root_def_id, |r| {
+        for_each_late_bound_region_in_item(self.tcx, mir_def_id, |r| {
             debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = self.next_nll_region_var(FR);
@@ -803,21 +839,44 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
     }
 }
 
-/// Iterates over the late-bound regions defined on fn_def_id and
-/// invokes `f` with the liberated form of each one.
-fn for_each_late_bound_region_defined_on<'tcx>(
+/// Iterates over the late-bound regions defined on `mir_def_id` and all of its
+/// parents, up to the typeck root, and invokes `f` with the liberated form
+/// of each one.
+fn for_each_late_bound_region_in_recursive_scope<'tcx>(
     tcx: TyCtxt<'tcx>,
-    fn_def_id: DefId,
+    mut mir_def_id: LocalDefId,
     mut f: impl FnMut(ty::Region<'tcx>),
 ) {
-    if let Some(late_bounds) = tcx.is_late_bound_map(fn_def_id.expect_local()) {
-        for &region_def_id in late_bounds.iter() {
-            let name = tcx.item_name(region_def_id.to_def_id());
-            let liberated_region = tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                scope: fn_def_id,
-                bound_region: ty::BoundRegionKind::BrNamed(region_def_id.to_def_id(), name),
-            }));
-            f(liberated_region);
+    let typeck_root_def_id = tcx.typeck_root_def_id(mir_def_id.to_def_id());
+
+    // Walk up the tree, collecting late-bound regions until we hit the typeck root
+    loop {
+        for_each_late_bound_region_in_item(tcx, mir_def_id, &mut f);
+
+        if mir_def_id.to_def_id() == typeck_root_def_id {
+            break;
+        } else {
+            mir_def_id = tcx.local_parent(mir_def_id);
         }
     }
 }
+
+/// Iterates over the late-bound regions defined on `mir_def_id` and all of its
+/// parents, up to the typeck root, and invokes `f` with the liberated form
+/// of each one.
+fn for_each_late_bound_region_in_item<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    mir_def_id: LocalDefId,
+    mut f: impl FnMut(ty::Region<'tcx>),
+) {
+    if !tcx.def_kind(mir_def_id).is_fn_like() {
+        return;
+    }
+
+    for bound_var in tcx.late_bound_vars(tcx.hir().local_def_id_to_hir_id(mir_def_id)) {
+        let ty::BoundVariableKind::Region(bound_region) = bound_var else { continue; };
+        let liberated_region = tcx
+            .mk_region(ty::ReFree(ty::FreeRegion { scope: mir_def_id.to_def_id(), bound_region }));
+        f(liberated_region);
+    }
+}
diff --git a/compiler/rustc_borrowck/src/used_muts.rs b/compiler/rustc_borrowck/src/used_muts.rs
index 8833753b1..e297b1230 100644
--- a/compiler/rustc_borrowck/src/used_muts.rs
+++ b/compiler/rustc_borrowck/src/used_muts.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::mir::visit::{PlaceContext, Visitor};
 use rustc_middle::mir::{