Adding debian version 1.65.0+dfsg1-2.debian/1.65.0+dfsg1-2

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

27 files changed, 831 insertions, 569 deletions

diff --git a/compiler/rustc_borrowck/src/constraint_generation.rs b/compiler/rustc_borrowck/src/constraint_generation.rs
index 5e9cec5c3..144fd15fc 100644
--- a/compiler/rustc_borrowck/src/constraint_generation.rs
+++ b/compiler/rustc_borrowck/src/constraint_generation.rs
@@ -31,7 +31,7 @@ pub(super) fn generate_constraints<'cx, 'tcx>(
         body,
     };
 
-    for (bb, data) in body.basic_blocks().iter_enumerated() {
+    for (bb, data) in body.basic_blocks.iter_enumerated() {
         cg.visit_basic_block_data(bb, data);
     }
 }
diff --git a/compiler/rustc_borrowck/src/constraints/mod.rs b/compiler/rustc_borrowck/src/constraints/mod.rs
index a504d0c91..df0412813 100644
--- a/compiler/rustc_borrowck/src/constraints/mod.rs
+++ b/compiler/rustc_borrowck/src/constraints/mod.rs
@@ -21,10 +21,7 @@ pub(crate) struct OutlivesConstraintSet<'tcx> {
 
 impl<'tcx> OutlivesConstraintSet<'tcx> {
     pub(crate) fn push(&mut self, constraint: OutlivesConstraint<'tcx>) {
-        debug!(
-            "OutlivesConstraintSet::push({:?}: {:?} @ {:?}",
-            constraint.sup, constraint.sub, constraint.locations
-        );
+        debug!("OutlivesConstraintSet::push({:?})", constraint);
         if constraint.sup == constraint.sub {
             // 'a: 'a is pretty uninteresting
             return;
@@ -73,7 +70,7 @@ impl<'tcx> Index<OutlivesConstraintIndex> for OutlivesConstraintSet<'tcx> {
     }
 }
 
-#[derive(Clone, PartialEq, Eq)]
+#[derive(Copy, Clone, PartialEq, Eq)]
 pub struct OutlivesConstraint<'tcx> {
     // NB. The ordering here is not significant for correctness, but
     // it is for convenience. Before we dump the constraints in the
@@ -105,8 +102,8 @@ impl<'tcx> fmt::Debug for OutlivesConstraint<'tcx> {
     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             formatter,
-            "({:?}: {:?}) due to {:?} ({:?})",
-            self.sup, self.sub, self.locations, self.variance_info
+            "({:?}: {:?}) due to {:?} ({:?}) ({:?})",
+            self.sup, self.sub, self.locations, self.variance_info, self.category,
         )
     }
 }
diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 97d5a8d15..9f7a4d499 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -143,7 +143,7 @@ struct OutOfScopePrecomputer<'a, 'tcx> {
 impl<'a, 'tcx> OutOfScopePrecomputer<'a, 'tcx> {
     fn new(body: &'a Body<'tcx>, regioncx: &'a RegionInferenceContext<'tcx>) -> Self {
         OutOfScopePrecomputer {
-            visited: BitSet::new_empty(body.basic_blocks().len()),
+            visited: BitSet::new_empty(body.basic_blocks.len()),
             visit_stack: vec![],
             body,
             regioncx,
@@ -391,7 +391,7 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
             | mir::StatementKind::Retag { .. }
             | mir::StatementKind::AscribeUserType(..)
             | mir::StatementKind::Coverage(..)
-            | mir::StatementKind::CopyNonOverlapping(..)
+            | mir::StatementKind::Intrinsic(..)
             | mir::StatementKind::Nop => {}
         }
     }
diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index 1ef2b0ae9..b1def1892 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -484,9 +484,7 @@ fn try_extract_error_from_region_constraints<'tcx>(
     };
     nice_error.try_report_from_nll().or_else(|| {
         if let SubregionOrigin::Subtype(trace) = cause {
-            Some(
-                infcx.report_and_explain_type_error(*trace, &TypeError::RegionsPlaceholderMismatch),
-            )
+            Some(infcx.report_and_explain_type_error(*trace, TypeError::RegionsPlaceholderMismatch))
         } else {
             None
         }
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 8bc8964bb..f2204c242 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -258,7 +258,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             let ty = place.ty(self.body, self.infcx.tcx).ty;
 
             // If we're in pattern, we do nothing in favor of the previous suggestion (#80913).
-            if is_loop_move & !in_pattern {
+            // Same for if we're in a loop, see #101119.
+            if is_loop_move & !in_pattern && !matches!(use_spans, UseSpans::ClosureUse { .. }) {
                 if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
                     // We have a `&mut` ref, we need to reborrow on each iteration (#62112).
                     err.span_suggestion_verbose(
@@ -451,7 +452,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
     fn suggest_borrow_fn_like(
         &self,
-        err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>,
+        err: &mut Diagnostic,
         ty: Ty<'tcx>,
         move_sites: &[MoveSite],
         value_name: &str,
@@ -526,12 +527,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         true
     }
 
-    fn suggest_adding_copy_bounds(
-        &self,
-        err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>,
-        ty: Ty<'tcx>,
-        span: Span,
-    ) {
+    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());
 
@@ -1124,6 +1120,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
     /// short a lifetime. (But sometimes it is more useful to report
     /// it as a more direct conflict between the execution of a
     /// `Drop::drop` with an aliasing borrow.)
+    #[instrument(level = "debug", skip(self))]
     pub(crate) fn report_borrowed_value_does_not_live_long_enough(
         &mut self,
         location: Location,
@@ -1131,13 +1128,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         place_span: (Place<'tcx>, Span),
         kind: Option<WriteKind>,
     ) {
-        debug!(
-            "report_borrowed_value_does_not_live_long_enough(\
-             {:?}, {:?}, {:?}, {:?}\
-             )",
-            location, borrow, place_span, kind
-        );
-
         let drop_span = place_span.1;
         let root_place =
             self.prefixes(borrow.borrowed_place.as_ref(), PrefixSet::All).last().unwrap();
@@ -1194,10 +1184,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let kind_place = kind.filter(|_| place_desc.is_some()).map(|k| (k, place_span.0));
         let explanation = self.explain_why_borrow_contains_point(location, &borrow, kind_place);
 
-        debug!(
-            "report_borrowed_value_does_not_live_long_enough(place_desc: {:?}, explanation: {:?})",
-            place_desc, explanation
-        );
+        debug!(?place_desc, ?explanation);
+
         let err = match (place_desc, explanation) {
             // If the outlives constraint comes from inside the closure,
             // for example:
@@ -1469,6 +1457,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         err
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn report_temporary_value_does_not_live_long_enough(
         &mut self,
         location: Location,
@@ -1478,13 +1467,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         proper_span: Span,
         explanation: BorrowExplanation<'tcx>,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
-        debug!(
-            "report_temporary_value_does_not_live_long_enough(\
-             {:?}, {:?}, {:?}, {:?}\
-             )",
-            location, borrow, drop_span, proper_span
-        );
-
         if let BorrowExplanation::MustBeValidFor { category, span, from_closure: false, .. } =
             explanation
         {
diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index 72aee0267..1c01e78ab 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -15,7 +15,7 @@ use rustc_middle::ty::{self, RegionVid, TyCtxt};
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, DesugaringKind, Span};
 
-use crate::region_infer::BlameConstraint;
+use crate::region_infer::{BlameConstraint, ExtraConstraintInfo};
 use crate::{
     borrow_set::BorrowData, nll::ConstraintDescription, region_infer::Cause, MirBorrowckCtxt,
     WriteKind,
@@ -38,6 +38,7 @@ pub(crate) enum BorrowExplanation<'tcx> {
         span: Span,
         region_name: RegionName,
         opt_place_desc: Option<String>,
+        extra_info: Vec<ExtraConstraintInfo>,
     },
     Unexplained,
 }
@@ -243,6 +244,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
                 ref region_name,
                 ref opt_place_desc,
                 from_closure: _,
+                ref extra_info,
             } => {
                 region_name.highlight_region_name(err);
 
@@ -268,18 +270,30 @@ impl<'tcx> BorrowExplanation<'tcx> {
                     );
                 };
 
+                for extra in extra_info {
+                    match extra {
+                        ExtraConstraintInfo::PlaceholderFromPredicate(span) => {
+                            err.span_note(*span, format!("due to current limitations in the borrow checker, this implies a `'static` lifetime"));
+                        }
+                    }
+                }
+
                 self.add_lifetime_bound_suggestion_to_diagnostic(err, &category, span, region_name);
             }
             _ => {}
         }
     }
-    pub(crate) fn add_lifetime_bound_suggestion_to_diagnostic(
+
+    fn add_lifetime_bound_suggestion_to_diagnostic(
         &self,
         err: &mut Diagnostic,
         category: &ConstraintCategory<'tcx>,
         span: Span,
         region_name: &RegionName,
     ) {
+        if !span.is_desugaring(DesugaringKind::OpaqueTy) {
+            return;
+        }
         if let ConstraintCategory::OpaqueType = category {
             let suggestable_name =
                 if region_name.was_named() { region_name.name } else { kw::UnderscoreLifetime };
@@ -305,18 +319,17 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         &self,
         borrow_region: RegionVid,
         outlived_region: RegionVid,
-    ) -> (ConstraintCategory<'tcx>, bool, Span, Option<RegionName>) {
-        let BlameConstraint { category, from_closure, cause, variance_info: _ } =
-            self.regioncx.best_blame_constraint(
-                &self.body,
-                borrow_region,
-                NllRegionVariableOrigin::FreeRegion,
-                |r| self.regioncx.provides_universal_region(r, borrow_region, outlived_region),
-            );
+    ) -> (ConstraintCategory<'tcx>, bool, Span, Option<RegionName>, Vec<ExtraConstraintInfo>) {
+        let (blame_constraint, extra_info) = self.regioncx.best_blame_constraint(
+            borrow_region,
+            NllRegionVariableOrigin::FreeRegion,
+            |r| self.regioncx.provides_universal_region(r, borrow_region, outlived_region),
+        );
+        let BlameConstraint { category, from_closure, cause, .. } = blame_constraint;
 
         let outlived_fr_name = self.give_region_a_name(outlived_region);
 
-        (category, from_closure, cause.span, outlived_fr_name)
+        (category, from_closure, cause.span, outlived_fr_name, extra_info)
     }
 
     /// Returns structured explanation for *why* the borrow contains the
@@ -332,26 +345,22 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
     ///   - second half is the place being accessed
     ///
     /// [d]: https://rust-lang.github.io/rfcs/2094-nll.html#leveraging-intuition-framing-errors-in-terms-of-points
+    #[instrument(level = "debug", skip(self))]
     pub(crate) fn explain_why_borrow_contains_point(
         &self,
         location: Location,
         borrow: &BorrowData<'tcx>,
         kind_place: Option<(WriteKind, Place<'tcx>)>,
     ) -> BorrowExplanation<'tcx> {
-        debug!(
-            "explain_why_borrow_contains_point(location={:?}, borrow={:?}, kind_place={:?})",
-            location, borrow, kind_place
-        );
-
         let regioncx = &self.regioncx;
         let body: &Body<'_> = &self.body;
         let tcx = self.infcx.tcx;
 
         let borrow_region_vid = borrow.region;
-        debug!("explain_why_borrow_contains_point: borrow_region_vid={:?}", borrow_region_vid);
+        debug!(?borrow_region_vid);
 
         let region_sub = self.regioncx.find_sub_region_live_at(borrow_region_vid, location);
-        debug!("explain_why_borrow_contains_point: region_sub={:?}", region_sub);
+        debug!(?region_sub);
 
         match find_use::find(body, regioncx, tcx, region_sub, location) {
             Some(Cause::LiveVar(local, location)) => {
@@ -392,7 +401,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
             None => {
                 if let Some(region) = self.to_error_region_vid(borrow_region_vid) {
-                    let (category, from_closure, span, region_name) =
+                    let (category, from_closure, span, region_name, extra_info) =
                         self.free_region_constraint_info(borrow_region_vid, region);
                     if let Some(region_name) = region_name {
                         let opt_place_desc = self.describe_place(borrow.borrowed_place.as_ref());
@@ -402,19 +411,14 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             span,
                             region_name,
                             opt_place_desc,
+                            extra_info,
                         }
                     } else {
-                        debug!(
-                            "explain_why_borrow_contains_point: \
-                             Could not generate a region name"
-                        );
+                        debug!("Could not generate a region name");
                         BorrowExplanation::Unexplained
                     }
                 } else {
-                    debug!(
-                        "explain_why_borrow_contains_point: \
-                         Could not generate an error region vid"
-                    );
+                    debug!("Could not generate an error region vid");
                     BorrowExplanation::Unexplained
                 }
             }
@@ -455,7 +459,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 return outmost_back_edge;
             }
 
-            let block = &self.body.basic_blocks()[location.block];
+            let block = &self.body.basic_blocks[location.block];
 
             if location.statement_index < block.statements.len() {
                 let successor = location.successor_within_block();
@@ -514,7 +518,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
 
         if loop_head.dominates(from, &self.dominators) {
-            let block = &self.body.basic_blocks()[from.block];
+            let block = &self.body.basic_blocks[from.block];
 
             if from.statement_index < block.statements.len() {
                 let successor = from.successor_within_block();
@@ -564,7 +568,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             UseSpans::PatUse(span)
             | UseSpans::OtherUse(span)
             | UseSpans::FnSelfUse { var_span: span, .. } => {
-                let block = &self.body.basic_blocks()[location.block];
+                let block = &self.body.basic_blocks[location.block];
 
                 let kind = if let Some(&Statement {
                     kind: StatementKind::FakeRead(box (FakeReadCause::ForLet(_), _)),
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index 098e8de94..683084cf0 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -1086,14 +1086,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             ),
                         );
                     }
-                    if is_option_or_result && maybe_reinitialized_locations_is_empty {
-                        err.span_suggestion_verbose(
-                            fn_call_span.shrink_to_lo(),
-                            "consider calling `.as_ref()` to borrow the type's contents",
-                            "as_ref().",
-                            Applicability::MachineApplicable,
-                        );
-                    }
                     // Avoid pointing to the same function in multiple different
                     // error messages.
                     if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {
@@ -1102,6 +1094,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             &format!("this function takes ownership of the receiver `self`, which moves {}", place_name)
                         );
                     }
+                    if is_option_or_result && maybe_reinitialized_locations_is_empty {
+                        err.span_label(
+                            var_span,
+                            "help: consider calling `.as_ref()` or `.as_mut()` to borrow the type's contents",
+                        );
+                    }
                 }
                 // Other desugarings takes &self, which cannot cause a move
                 _ => {}
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
index cb3cd479a..8d4c38d3a 100644
--- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -88,7 +88,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 if let Some(StatementKind::Assign(box (
                     place,
                     Rvalue::Use(Operand::Move(move_from)),
-                ))) = self.body.basic_blocks()[location.block]
+                ))) = self.body.basic_blocks[location.block]
                     .statements
                     .get(location.statement_index)
                     .map(|stmt| &stmt.kind)
@@ -360,7 +360,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                 diag.span_label(upvar_span, "captured outer variable");
                 diag.span_label(
-                    self.body.span,
+                    self.infcx.tcx.def_span(def_id),
                     format!("captured by this `{closure_kind}` closure"),
                 );
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 0ad4abbce..6b5014fa9 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -1,23 +1,23 @@
+use rustc_errors::{
+    Applicability, Diagnostic, DiagnosticBuilder, EmissionGuarantee, ErrorGuaranteed,
+};
 use rustc_hir as hir;
+use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
 use rustc_middle::hir::map::Map;
 use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{
     hir::place::PlaceBase,
-    mir::{
-        self, BindingForm, ClearCrossCrate, ImplicitSelfKind, Local, LocalDecl, LocalInfo,
-        LocalKind, Location,
-    },
+    mir::{self, BindingForm, ClearCrossCrate, Local, LocalDecl, LocalInfo, LocalKind, Location},
 };
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::{kw, Symbol};
-use rustc_span::{BytePos, Span};
+use rustc_span::{sym, BytePos, Span};
 
 use crate::diagnostics::BorrowedContentSource;
 use crate::MirBorrowckCtxt;
 use rustc_const_eval::util::collect_writes::FindAssignments;
-use rustc_errors::{Applicability, Diagnostic};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub(crate) enum AccessKind {
@@ -309,7 +309,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     && !matches!(
                         decl.local_info,
                         Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(
-                            ImplicitSelfKind::MutRef
+                            hir::ImplicitSelfKind::MutRef
                         ))))
                     )
                 {
@@ -364,7 +364,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                 if let Some(Node::Pat(pat)) = self.infcx.tcx.hir().find(upvar_hir_id)
                     && let hir::PatKind::Binding(
-                        hir::BindingAnnotation::Unannotated,
+                        hir::BindingAnnotation::NONE,
                         _,
                         upvar_ident,
                         _,
@@ -614,6 +614,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                             "trait `IndexMut` is required to modify indexed content, \
                                 but it is not implemented for `{ty}`",
                         ));
+                        self.suggest_map_index_mut_alternatives(ty, &mut err, span);
                     }
                     _ => (),
                 }
@@ -627,6 +628,127 @@ 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,
+    ) {
+        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> {
+                assign_span: Span,
+                err: &'a mut DiagnosticBuilder<'b, G>,
+                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>) {
+                    hir::intravisit::walk_stmt(self, stmt);
+                    let expr = match stmt.kind {
+                        hir::StmtKind::Semi(expr) | hir::StmtKind::Expr(expr) => expr,
+                        hir::StmtKind::Local(hir::Local { init: Some(expr), .. }) => expr,
+                        _ => {
+                            return;
+                        }
+                    };
+                    if let hir::ExprKind::Assign(place, rv, _sp) = expr.kind
+                        && let hir::ExprKind::Index(val, index) = place.kind
+                        && (expr.span == self.assign_span || place.span == self.assign_span)
+                    {
+                        // val[index] = rv;
+                        // ---------- place
+                        self.err.multipart_suggestions(
+                            &format!(
+                                "to modify a `{}`, use `.get_mut()`, `.insert()` or the entry API",
+                                self.ty,
+                            ),
+                            vec![
+                                vec![ // val.insert(index, rv);
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".insert(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(rv.span.lo()),
+                                        ", ".to_string(),
+                                    ),
+                                    (rv.span.shrink_to_hi(), ")".to_string()),
+                                ],
+                                vec![ // val.get_mut(index).map(|v| { *v = rv; });
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".get_mut(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(place.span.hi()),
+                                        ").map(|val| { *val".to_string(),
+                                    ),
+                                    (
+                                        rv.span.shrink_to_hi(),
+                                        "; })".to_string(),
+                                    ),
+                                ],
+                                vec![ // let x = val.entry(index).or_insert(rv);
+                                    (val.span.shrink_to_lo(), "let val = ".to_string()),
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".entry(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(rv.span.lo()),
+                                        ").or_insert(".to_string(),
+                                    ),
+                                    (rv.span.shrink_to_hi(), ")".to_string()),
+                                ],
+                            ].into_iter(),
+                            Applicability::MachineApplicable,
+                        );
+                        self.suggested = true;
+                    } else if let hir::ExprKind::MethodCall(_path, receiver, _, sp) = expr.kind
+                        && let hir::ExprKind::Index(val, index) = receiver.kind
+                        && expr.span == self.assign_span
+                    {
+                        // val[index].path(args..);
+                        self.err.multipart_suggestion(
+                            &format!("to modify a `{}` use `.get_mut()`", self.ty),
+                            vec![
+                                (
+                                    val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                    ".get_mut(".to_string(),
+                                ),
+                                (
+                                    index.span.shrink_to_hi().with_hi(receiver.span.hi()),
+                                    ").map(|val| val".to_string(),
+                                ),
+                                (sp.shrink_to_hi(), ")".to_string()),
+                            ],
+                            Applicability::MachineApplicable,
+                        );
+                        self.suggested = true;
+                    }
+                }
+            }
+            let hir_map = self.infcx.tcx.hir();
+            let def_id = self.body.source.def_id();
+            let hir_id = hir_map.local_def_id_to_hir_id(def_id.as_local().unwrap());
+            let node = hir_map.find(hir_id);
+            let Some(hir::Node::Item(item)) = node else { return; };
+            let hir::ItemKind::Fn(.., body_id) = item.kind else { return; };
+            let body = self.infcx.tcx.hir().body(body_id);
+            let mut v = V { assign_span: span, err, ty, suggested: false };
+            v.visit_body(body);
+            if !v.suggested {
+                err.help(&format!(
+                    "to modify a `{ty}`, use `.get_mut()`, `.insert()` or the entry API",
+                ));
+            }
+        }
+    }
+
     /// User cannot make signature of a trait mutable without changing the
     /// trait. So we find if this error belongs to a trait and if so we move
     /// suggestion to the trait or disable it if it is out of scope of this crate
@@ -786,11 +908,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                                         [
                                                             Expr {
                                                                 kind:
-                                                                    MethodCall(
-                                                                        path_segment,
-                                                                        _args,
-                                                                        span,
-                                                                    ),
+                                                                    MethodCall(path_segment, _, _, span),
                                                                 hir_id,
                                                                 ..
                                                             },
@@ -810,10 +928,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 _,
             ) = hir_map.body(fn_body_id).value.kind
             {
-                let opt_suggestions = path_segment
-                    .hir_id
-                    .map(|path_hir_id| self.infcx.tcx.typeck(path_hir_id.owner))
-                    .and_then(|typeck| typeck.type_dependent_def_id(*hir_id))
+                let opt_suggestions = self
+                    .infcx
+                    .tcx
+                    .typeck(path_segment.hir_id.owner)
+                    .type_dependent_def_id(*hir_id)
                     .and_then(|def_id| self.infcx.tcx.impl_of_method(def_id))
                     .map(|def_id| self.infcx.tcx.associated_items(def_id))
                     .map(|assoc_items| {
@@ -851,6 +970,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
         let hir = self.infcx.tcx.hir();
         let closure_id = self.mir_hir_id();
+        let closure_span = self.infcx.tcx.def_span(self.mir_def_id());
         let fn_call_id = hir.get_parent_node(closure_id);
         let node = hir.get(fn_call_id);
         let def_id = hir.enclosing_body_owner(fn_call_id);
@@ -902,7 +1022,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 if let Some(span) = arg {
                     err.span_label(span, "change this to accept `FnMut` instead of `Fn`");
                     err.span_label(func.span, "expects `Fn` instead of `FnMut`");
-                    err.span_label(self.body.span, "in this closure");
+                    err.span_label(closure_span, "in this closure");
                     look_at_return = false;
                 }
             }
@@ -928,7 +1048,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                         sig.decl.output.span(),
                         "change this to return `FnMut` instead of `Fn`",
                     );
-                    err.span_label(self.body.span, "in this closure");
+                    err.span_label(closure_span, "in this closure");
                 }
                 _ => {}
             }
@@ -952,7 +1072,7 @@ fn mut_borrow_of_mutable_ref(local_decl: &LocalDecl<'_>, local_name: Option<Symb
             //
             // Deliberately fall into this case for all implicit self types,
             // so that we don't fall in to the next case with them.
-            *kind == mir::ImplicitSelfKind::MutRef
+            *kind == hir::ImplicitSelfKind::MutRef
         }
         _ if Some(kw::SelfLower) == local_name => {
             // Otherwise, check if the name is the `self` keyword - in which case
diff --git a/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs b/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs
index d359d7efb..35c3df768 100644
--- a/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs
@@ -6,7 +6,6 @@ use rustc_errors::Diagnostic;
 use rustc_middle::ty::RegionVid;
 use smallvec::SmallVec;
 use std::collections::BTreeMap;
-use tracing::debug;
 
 use crate::MirBorrowckCtxt;
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index 176090c3b..34be2874f 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -1,3 +1,5 @@
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 //! Error reporting machinery for lifetime errors.
 
 use rustc_data_structures::fx::FxHashSet;
@@ -23,10 +25,13 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::Span;
 
 use crate::borrowck_errors;
-use crate::session_diagnostics::GenericDoesNotLiveLongEnough;
+use crate::session_diagnostics::{
+    FnMutError, FnMutReturnTypeErr, GenericDoesNotLiveLongEnough, LifetimeOutliveErr,
+    LifetimeReturnCategoryErr, RequireStaticErr, VarHereDenote,
+};
 
 use super::{OutlivesSuggestionBuilder, RegionName};
-use crate::region_infer::BlameConstraint;
+use crate::region_infer::{BlameConstraint, ExtraConstraintInfo};
 use crate::{
     nll::ConstraintDescription,
     region_infer::{values::RegionElement, TypeTest},
@@ -229,7 +234,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                     // Find the code to blame for the fact that `longer_fr` outlives `error_fr`.
                     let (_, cause) = self.regioncx.find_outlives_blame_span(
-                        &self.body,
                         longer_fr,
                         NllRegionVariableOrigin::Placeholder(placeholder),
                         error_vid,
@@ -350,10 +354,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     ) {
         debug!("report_region_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr);
 
-        let BlameConstraint { category, cause, variance_info, from_closure: _ } =
-            self.regioncx.best_blame_constraint(&self.body, fr, fr_origin, |r| {
+        let (blame_constraint, extra_info) =
+            self.regioncx.best_blame_constraint(fr, fr_origin, |r| {
                 self.regioncx.provides_universal_region(r, fr, outlived_fr)
             });
+        let BlameConstraint { category, cause, variance_info, .. } = blame_constraint;
 
         debug!("report_region_error: category={:?} {:?} {:?}", category, cause, variance_info);
 
@@ -462,6 +467,14 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             }
         }
 
+        for extra in extra_info {
+            match extra {
+                ExtraConstraintInfo::PlaceholderFromPredicate(span) => {
+                    diag.span_note(span, format!("due to current limitations in the borrow checker, this implies a `'static` lifetime"));
+                }
+            }
+        }
+
         self.buffer_error(diag);
     }
 
@@ -488,12 +501,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let ErrorConstraintInfo { outlived_fr, span, .. } = errci;
 
-        let mut diag = self
-            .infcx
-            .tcx
-            .sess
-            .struct_span_err(*span, "captured variable cannot escape `FnMut` closure body");
-
         let mut output_ty = self.regioncx.universal_regions().unnormalized_output_ty;
         if let ty::Opaque(def_id, _) = *output_ty.kind() {
             output_ty = self.infcx.tcx.type_of(def_id)
@@ -501,19 +508,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
         debug!("report_fnmut_error: output_ty={:?}", output_ty);
 
-        let message = match output_ty.kind() {
-            ty::Closure(_, _) => {
-                "returns a closure that contains a reference to a captured variable, which then \
-                 escapes the closure body"
-            }
-            ty::Adt(def, _) if self.infcx.tcx.is_diagnostic_item(sym::gen_future, def.did()) => {
-                "returns an `async` block that contains a reference to a captured variable, which then \
-                 escapes the closure body"
-            }
-            _ => "returns a reference to a captured variable which escapes the closure body",
+        let err = FnMutError {
+            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()) =>
+                {
+                    FnMutReturnTypeErr::ReturnAsyncBlock { span: *span }
+                }
+                _ => FnMutReturnTypeErr::ReturnRef { span: *span },
+            },
         };
 
-        diag.span_label(*span, message);
+        let mut diag = self.infcx.tcx.sess.create_err(err);
 
         if let ReturnConstraint::ClosureUpvar(upvar_field) = kind {
             let def_id = match self.regioncx.universal_regions().defining_ty {
@@ -532,20 +540,16 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let upvars_map = self.infcx.tcx.upvars_mentioned(def_id).unwrap();
                 let upvar_def_span = self.infcx.tcx.hir().span(def_hir);
                 let upvar_span = upvars_map.get(&def_hir).unwrap().span;
-                diag.span_label(upvar_def_span, "variable defined here");
-                diag.span_label(upvar_span, "variable captured here");
+                diag.subdiagnostic(VarHereDenote::Defined { span: upvar_def_span });
+                diag.subdiagnostic(VarHereDenote::Captured { span: upvar_span });
             }
         }
 
         if let Some(fr_span) = self.give_region_a_name(*outlived_fr).unwrap().span() {
-            diag.span_label(fr_span, "inferred to be a `FnMut` closure");
+            diag.subdiagnostic(VarHereDenote::FnMutInferred { span: fr_span });
         }
 
-        diag.note(
-            "`FnMut` closures only have access to their captured variables while they are \
-             executing...",
-        );
-        diag.note("...therefore, they cannot allow references to captured variables to escape");
+        self.suggest_move_on_borrowing_closure(&mut diag);
 
         diag
     }
@@ -562,6 +566,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     /// LL |     ref_obj(x)
     ///    |     ^^^^^^^^^^ `x` escapes the function body here
     /// ```
+    #[instrument(level = "debug", skip(self))]
     fn report_escaping_data_error(
         &self,
         errci: &ErrorConstraintInfo<'tcx>,
@@ -680,42 +685,37 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             ..
         } = errci;
 
-        let mut diag =
-            self.infcx.tcx.sess.struct_span_err(*span, "lifetime may not live long enough");
-
         let (_, mir_def_name) =
             self.infcx.tcx.article_and_description(self.mir_def_id().to_def_id());
 
+        let err = LifetimeOutliveErr { span: *span };
+        let mut diag = self.infcx.tcx.sess.create_err(err);
+
         let fr_name = self.give_region_a_name(*fr).unwrap();
         fr_name.highlight_region_name(&mut diag);
         let outlived_fr_name = self.give_region_a_name(*outlived_fr).unwrap();
         outlived_fr_name.highlight_region_name(&mut diag);
 
-        match (category, outlived_fr_is_local, fr_is_local) {
-            (ConstraintCategory::Return(_), true, _) => {
-                diag.span_label(
-                    *span,
-                    format!(
-                        "{mir_def_name} was supposed to return data with lifetime `{outlived_fr_name}` but it is returning \
-                         data with lifetime `{fr_name}`",
-                    ),
-                );
-            }
-            _ => {
-                diag.span_label(
-                    *span,
-                    format!(
-                        "{}requires that `{}` must outlive `{}`",
-                        category.description(),
-                        fr_name,
-                        outlived_fr_name,
-                    ),
-                );
-            }
-        }
+        let err_category = match (category, outlived_fr_is_local, fr_is_local) {
+            (ConstraintCategory::Return(_), true, _) => LifetimeReturnCategoryErr::WrongReturn {
+                span: *span,
+                mir_def_name,
+                outlived_fr_name,
+                fr_name: &fr_name,
+            },
+            _ => LifetimeReturnCategoryErr::ShortReturn {
+                span: *span,
+                category_desc: category.description(),
+                free_region_name: &fr_name,
+                outlived_fr_name,
+            },
+        };
+
+        diag.subdiagnostic(err_category);
 
         self.add_static_impl_trait_suggestion(&mut diag, *fr, fr_name, *outlived_fr);
         self.suggest_adding_lifetime_params(&mut diag, *fr, *outlived_fr);
+        self.suggest_move_on_borrowing_closure(&mut diag);
 
         diag
     }
@@ -783,7 +783,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
     fn maybe_suggest_constrain_dyn_trait_impl(
         &self,
-        diag: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>,
+        diag: &mut Diagnostic,
         f: Region<'tcx>,
         o: Region<'tcx>,
         category: &ConstraintCategory<'tcx>,
@@ -860,7 +860,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     ident.span,
                     "calling this method introduces the `impl`'s 'static` requirement",
                 );
-                err.span_note(multi_span, "the used `impl` has a `'static` requirement");
+                err.subdiagnostic(RequireStaticErr::UsedImpl { multi_span });
                 err.span_suggestion_verbose(
                     span.shrink_to_hi(),
                     "consider relaxing the implicit `'static` requirement",
@@ -901,4 +901,46 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
         suggest_adding_lifetime_params(self.infcx.tcx, sub, ty_sup, ty_sub, diag);
     }
+
+    fn suggest_move_on_borrowing_closure(&self, diag: &mut Diagnostic) {
+        let map = self.infcx.tcx.hir();
+        let body_id = map.body_owned_by(self.mir_def_id());
+        let expr = &map.body(body_id).value;
+        let mut closure_span = None::<rustc_span::Span>;
+        match expr.kind {
+            hir::ExprKind::MethodCall(.., args, _) => {
+                for arg in args {
+                    if let hir::ExprKind::Closure(hir::Closure {
+                        capture_clause: hir::CaptureBy::Ref,
+                        ..
+                    }) = arg.kind
+                    {
+                        closure_span = Some(arg.span.shrink_to_lo());
+                        break;
+                    }
+                }
+            }
+            hir::ExprKind::Block(blk, _) => {
+                if let Some(ref expr) = blk.expr {
+                    // only when the block is a closure
+                    if let hir::ExprKind::Closure(hir::Closure {
+                        capture_clause: hir::CaptureBy::Ref,
+                        ..
+                    }) = expr.kind
+                    {
+                        closure_span = Some(expr.span.shrink_to_lo());
+                    }
+                }
+            }
+            _ => {}
+        }
+        if let Some(closure_span) = closure_span {
+            diag.span_suggestion_verbose(
+                closure_span,
+                "consider adding 'move' keyword before the nested closure",
+                "move ",
+                Applicability::MaybeIncorrect,
+            );
+        }
+    }
 }
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index a87e8bd5b..6c1eaa809 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -265,7 +265,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
     /// *user* has a name for. In that case, we'll be able to map
     /// `fr` to a `Region<'tcx>`, and that region will be one of
     /// named variants.
-    #[tracing::instrument(level = "trace", skip(self))]
+    #[instrument(level = "trace", skip(self))]
     fn give_name_from_error_region(&self, fr: RegionVid) -> Option<RegionName> {
         let error_region = self.to_error_region(fr)?;
 
@@ -357,11 +357,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                 ty::BoundRegionKind::BrAnon(_) => None,
             },
 
-            ty::ReLateBound(..)
-            | ty::ReVar(..)
-            | ty::RePlaceholder(..)
-            | ty::ReEmpty(_)
-            | ty::ReErased => None,
+            ty::ReLateBound(..) | ty::ReVar(..) | ty::RePlaceholder(..) | ty::ReErased => None,
         }
     }
 
@@ -373,7 +369,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
     ///  | fn foo(x: &u32) { .. }
     ///           ------- fully elaborated type of `x` is `&'1 u32`
     /// ```
-    #[tracing::instrument(level = "trace", skip(self))]
+    #[instrument(level = "trace", skip(self))]
     fn give_name_if_anonymous_region_appears_in_arguments(
         &self,
         fr: RegionVid,
@@ -662,7 +658,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
     ///  | let x = Some(&22);
     ///        - fully elaborated type of `x` is `Option<&'1 u32>`
     /// ```
-    #[tracing::instrument(level = "trace", skip(self))]
+    #[instrument(level = "trace", skip(self))]
     fn give_name_if_anonymous_region_appears_in_upvars(&self, fr: RegionVid) -> Option<RegionName> {
         let upvar_index = self.regioncx.get_upvar_index_for_region(self.infcx.tcx, fr)?;
         let (upvar_name, upvar_span) = self.regioncx.get_upvar_name_and_span_for_region(
@@ -682,7 +678,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
     /// must be a closure since, in a free fn, such an argument would
     /// have to either also appear in an argument (if using elision)
     /// or be early bound (named, not in argument).
-    #[tracing::instrument(level = "trace", skip(self))]
+    #[instrument(level = "trace", skip(self))]
     fn give_name_if_anonymous_region_appears_in_output(&self, fr: RegionVid) -> Option<RegionName> {
         let tcx = self.infcx.tcx;
         let hir = tcx.hir();
@@ -772,7 +768,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
     fn get_future_inner_return_ty(&self, hir_ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {
         let hir = self.infcx.tcx.hir();
 
-        let hir::TyKind::OpaqueDef(id, _) = hir_ty.kind else {
+        let hir::TyKind::OpaqueDef(id, _, _) = hir_ty.kind else {
             span_bug!(
                 hir_ty.span,
                 "lowered return type of async fn is not OpaqueDef: {:?}",
@@ -814,7 +810,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
         }
     }
 
-    #[tracing::instrument(level = "trace", skip(self))]
+    #[instrument(level = "trace", skip(self))]
     fn give_name_if_anonymous_region_appears_in_yield_ty(
         &self,
         fr: RegionVid,
diff --git a/compiler/rustc_borrowck/src/invalidation.rs b/compiler/rustc_borrowck/src/invalidation.rs
index ec521b1cf..3157f861d 100644
--- a/compiler/rustc_borrowck/src/invalidation.rs
+++ b/compiler/rustc_borrowck/src/invalidation.rs
@@ -1,6 +1,6 @@
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_middle::mir::visit::Visitor;
-use rustc_middle::mir::{BasicBlock, Body, Location, Place, Rvalue};
+use rustc_middle::mir::{self, BasicBlock, Body, Location, NonDivergingIntrinsic, Place, Rvalue};
 use rustc_middle::mir::{BorrowKind, Mutability, Operand};
 use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind};
 use rustc_middle::mir::{Statement, StatementKind};
@@ -63,23 +63,24 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             StatementKind::FakeRead(box (_, _)) => {
                 // Only relevant for initialized/liveness/safety checks.
             }
-            StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping {
+            StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(op)) => {
+                self.consume_operand(location, op);
+            }
+            StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(mir::CopyNonOverlapping {
                 ref src,
                 ref dst,
                 ref count,
-            }) => {
+            })) => {
                 self.consume_operand(location, src);
                 self.consume_operand(location, dst);
                 self.consume_operand(location, count);
             }
-            StatementKind::Nop
+            // Only relevant for mir typeck
+            StatementKind::AscribeUserType(..)
+            // Doesn't have any language semantics
             | StatementKind::Coverage(..)
-            | StatementKind::AscribeUserType(..)
-            | StatementKind::Retag { .. }
-            | StatementKind::StorageLive(..) => {
-                // `Nop`, `AscribeUserType`, `Retag`, and `StorageLive` are irrelevant
-                // to borrow check.
-            }
+            // Does not actually affect borrowck
+            | StatementKind::StorageLive(..) => {}
             StatementKind::StorageDead(local) => {
                 self.access_place(
                     location,
@@ -88,7 +89,10 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                     LocalMutationIsAllowed::Yes,
                 );
             }
-            StatementKind::Deinit(..) | StatementKind::SetDiscriminant { .. } => {
+            StatementKind::Nop
+            | StatementKind::Retag { .. }
+            | StatementKind::Deinit(..)
+            | StatementKind::SetDiscriminant { .. } => {
                 bug!("Statement not allowed in this MIR phase")
             }
         }
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 3d8b07382..86da87d06 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -3,7 +3,7 @@
 #![allow(rustc::potential_query_instability)]
 #![feature(box_patterns)]
 #![feature(let_chains)]
-#![feature(let_else)]
+#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
@@ -19,15 +19,15 @@ extern crate tracing;
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::dominators::Dominators;
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::bit_set::ChunkedBitSet;
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::{DefiningAnchor, InferCtxt, TyCtxtInferExt};
 use rustc_middle::mir::{
-    traversal, Body, ClearCrossCrate, Local, Location, Mutability, Operand, Place, PlaceElem,
-    PlaceRef, VarDebugInfoContents,
+    traversal, Body, ClearCrossCrate, Local, Location, Mutability, NonDivergingIntrinsic, Operand,
+    Place, PlaceElem, PlaceRef, VarDebugInfoContents,
 };
 use rustc_middle::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind};
 use rustc_middle::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKind};
@@ -51,6 +51,8 @@ use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult, MoveData, MoveE
 use rustc_mir_dataflow::Analysis;
 use rustc_mir_dataflow::MoveDataParamEnv;
 
+use crate::session_diagnostics::VarNeedNotMut;
+
 use self::diagnostics::{AccessKind, RegionName};
 use self::location::LocationTable;
 use self::prefixes::PrefixSet;
@@ -425,17 +427,9 @@ fn do_mir_borrowck<'a, 'tcx>(
             continue;
         }
 
-        tcx.struct_span_lint_hir(UNUSED_MUT, lint_root, span, |lint| {
-            let mut_span = tcx.sess.source_map().span_until_non_whitespace(span);
-            lint.build("variable does not need to be mutable")
-                .span_suggestion_short(
-                    mut_span,
-                    "remove this `mut`",
-                    "",
-                    Applicability::MachineApplicable,
-                )
-                .emit();
-        })
+        let mut_span = tcx.sess.source_map().span_until_non_whitespace(span);
+
+        tcx.emit_spanned_lint(UNUSED_MUT, lint_root, span, VarNeedNotMut { span: mut_span })
     }
 
     let tainted_by_errors = mbcx.emit_errors();
@@ -597,22 +591,19 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                     flow_state,
                 );
             }
-            StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping {
-                ..
-            }) => {
-                span_bug!(
+            StatementKind::Intrinsic(box ref kind) => match kind {
+                NonDivergingIntrinsic::Assume(op) => self.consume_operand(location, (op, span), flow_state),
+                NonDivergingIntrinsic::CopyNonOverlapping(..) => span_bug!(
                     span,
                     "Unexpected CopyNonOverlapping, should only appear after lower_intrinsics",
                 )
             }
-            StatementKind::Nop
+            // Only relevant for mir typeck
+            StatementKind::AscribeUserType(..)
+            // Doesn't have any language semantics
             | StatementKind::Coverage(..)
-            | StatementKind::AscribeUserType(..)
-            | StatementKind::Retag { .. }
-            | StatementKind::StorageLive(..) => {
-                // `Nop`, `AscribeUserType`, `Retag`, and `StorageLive` are irrelevant
-                // to borrow check.
-            }
+            // Does not actually affect borrowck
+            | StatementKind::StorageLive(..) => {}
             StatementKind::StorageDead(local) => {
                 self.access_place(
                     location,
@@ -622,7 +613,10 @@ impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtx
                     flow_state,
                 );
             }
-            StatementKind::Deinit(..) | StatementKind::SetDiscriminant { .. } => {
+            StatementKind::Nop
+            | StatementKind::Retag { .. }
+            | StatementKind::Deinit(..)
+            | StatementKind::SetDiscriminant { .. } => {
                 bug!("Statement not allowed in this MIR phase")
             }
         }
@@ -982,6 +976,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self, flow_state))]
     fn check_access_for_conflict(
         &mut self,
         location: Location,
@@ -990,11 +985,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         rw: ReadOrWrite,
         flow_state: &Flows<'cx, 'tcx>,
     ) -> bool {
-        debug!(
-            "check_access_for_conflict(location={:?}, place_span={:?}, sd={:?}, rw={:?})",
-            location, place_span, sd, rw,
-        );
-
         let mut error_reported = false;
         let tcx = self.infcx.tcx;
         let body = self.body;
@@ -1458,13 +1448,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
     /// Checks whether a borrow of this place is invalidated when the function
     /// exits
+    #[instrument(level = "debug", skip(self))]
     fn check_for_invalidation_at_exit(
         &mut self,
         location: Location,
         borrow: &BorrowData<'tcx>,
         span: Span,
     ) {
-        debug!("check_for_invalidation_at_exit({:?})", borrow);
         let place = borrow.borrowed_place;
         let mut root_place = PlaceRef { local: place.local, projection: &[] };
 
diff --git a/compiler/rustc_borrowck/src/location.rs b/compiler/rustc_borrowck/src/location.rs
index 70a311694..877944d3d 100644
--- a/compiler/rustc_borrowck/src/location.rs
+++ b/compiler/rustc_borrowck/src/location.rs
@@ -33,7 +33,7 @@ impl LocationTable {
     pub(crate) fn new(body: &Body<'_>) -> Self {
         let mut num_points = 0;
         let statements_before_block = body
-            .basic_blocks()
+            .basic_blocks
             .iter()
             .map(|block_data| {
                 let v = num_points;
@@ -86,8 +86,7 @@ impl LocationTable {
         let (block, &first_index) = self
             .statements_before_block
             .iter_enumerated()
-            .filter(|(_, first_index)| **first_index <= point_index)
-            .last()
+            .rfind(|&(_, &first_index)| first_index <= point_index)
             .unwrap();
 
         let statement_index = (point_index - first_index) / 2;
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 0961203d7..12b2481cc 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -389,8 +389,9 @@ pub(super) fn dump_annotation<'a, 'tcx>(
     // viewing the intraprocedural state, the -Zdump-mir output is
     // better.
 
+    let def_span = tcx.def_span(body.source.def_id());
     let mut err = if let Some(closure_region_requirements) = closure_region_requirements {
-        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "external requirements");
+        let mut err = tcx.sess.diagnostic().span_note_diag(def_span, "external requirements");
 
         regioncx.annotate(tcx, &mut err);
 
@@ -409,7 +410,7 @@ pub(super) fn dump_annotation<'a, 'tcx>(
 
         err
     } else {
-        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "no external requirements");
+        let mut err = tcx.sess.diagnostic().span_note_diag(def_span, "no external requirements");
         regioncx.annotate(tcx, &mut err);
 
         err
diff --git a/compiler/rustc_borrowck/src/places_conflict.rs b/compiler/rustc_borrowck/src/places_conflict.rs
index 97335fd0d..6e5a96bee 100644
--- a/compiler/rustc_borrowck/src/places_conflict.rs
+++ b/compiler/rustc_borrowck/src/places_conflict.rs
@@ -44,6 +44,7 @@ pub(crate) fn places_conflict<'tcx>(
 /// access depth. The `bias` parameter is used to determine how the unknowable (comparing runtime
 /// array indices, for example) should be interpreted - this depends on what the caller wants in
 /// order to make the conservative choice and preserve soundness.
+#[instrument(level = "debug", skip(tcx, body))]
 pub(super) fn borrow_conflicts_with_place<'tcx>(
     tcx: TyCtxt<'tcx>,
     body: &Body<'tcx>,
@@ -53,11 +54,6 @@ pub(super) fn borrow_conflicts_with_place<'tcx>(
     access: AccessDepth,
     bias: PlaceConflictBias,
 ) -> bool {
-    debug!(
-        "borrow_conflicts_with_place({:?}, {:?}, {:?}, {:?})",
-        borrow_place, access_place, access, bias,
-    );
-
     // This Local/Local case is handled by the more general code below, but
     // it's so common that it's a speed win to check for it first.
     if let Some(l1) = borrow_place.as_local() && let Some(l2) = access_place.as_local() {
@@ -140,10 +136,9 @@ fn place_components_conflict<'tcx>(
     for (i, (borrow_c, &access_c)) in
         iter::zip(borrow_place.projection, access_place.projection).enumerate()
     {
-        debug!("borrow_conflicts_with_place: borrow_c = {:?}", borrow_c);
-        let borrow_proj_base = &borrow_place.projection[..i];
+        debug!(?borrow_c, ?access_c);
 
-        debug!("borrow_conflicts_with_place: access_c = {:?}", access_c);
+        let borrow_proj_base = &borrow_place.projection[..i];
 
         // Borrow and access path both have more components.
         //
@@ -180,7 +175,7 @@ fn place_components_conflict<'tcx>(
                 // idea, at least for now, so just give up and
                 // report a conflict. This is unsafe code anyway so
                 // the user could always use raw pointers.
-                debug!("borrow_conflicts_with_place: arbitrary -> conflict");
+                debug!("arbitrary -> conflict");
                 return true;
             }
             Overlap::EqualOrDisjoint => {
@@ -189,7 +184,7 @@ fn place_components_conflict<'tcx>(
             Overlap::Disjoint => {
                 // We have proven the borrow disjoint - further
                 // projections will remain disjoint.
-                debug!("borrow_conflicts_with_place: disjoint");
+                debug!("disjoint");
                 return false;
             }
         }
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 2894c6d29..244e6e342 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -135,7 +135,6 @@ 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(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd)]
 pub(crate) struct AppliedMemberConstraint {
     /// The SCC that was affected. (The "member region".)
     ///
@@ -246,6 +245,11 @@ enum Trace<'tcx> {
     NotVisited,
 }
 
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum ExtraConstraintInfo {
+    PlaceholderFromPredicate(Span),
+}
+
 impl<'tcx> RegionInferenceContext<'tcx> {
     /// Creates a new region inference context with a total of
     /// `num_region_variables` valid inference variables; the first N
@@ -591,13 +595,12 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // constraints were too strong, and if so, emit or propagate those errors.
         if infcx.tcx.sess.opts.unstable_opts.polonius {
             self.check_polonius_subset_errors(
-                body,
                 outlives_requirements.as_mut(),
                 &mut errors_buffer,
                 polonius_output.expect("Polonius output is unavailable despite `-Z polonius`"),
             );
         } else {
-            self.check_universal_regions(body, outlives_requirements.as_mut(), &mut errors_buffer);
+            self.check_universal_regions(outlives_requirements.as_mut(), &mut errors_buffer);
         }
 
         if errors_buffer.is_empty() {
@@ -1139,7 +1142,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///   include the CFG anyhow.
     /// - For each `end('x)` element in `'r`, compute the mutual LUB, yielding
     ///   a result `'y`.
-    #[instrument(skip(self), level = "debug")]
+    #[instrument(skip(self), level = "debug", ret)]
     pub(crate) fn universal_upper_bound(&self, r: RegionVid) -> RegionVid {
         debug!(r = %self.region_value_str(r));
 
@@ -1151,8 +1154,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             lub = self.universal_region_relations.postdom_upper_bound(lub, ur);
         }
 
-        debug!(?lub);
-
         lub
     }
 
@@ -1167,8 +1168,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// Therefore, this method should only be used in diagnostic code,
     /// where displaying *some* named universal region is better than
     /// falling back to 'static.
+    #[instrument(level = "debug", skip(self))]
     pub(crate) fn approx_universal_upper_bound(&self, r: RegionVid) -> RegionVid {
-        debug!("approx_universal_upper_bound(r={:?}={})", r, self.region_value_str(r));
+        debug!("{}", self.region_value_str(r));
 
         // Find the smallest universal region that contains all other
         // universal regions within `region`.
@@ -1177,7 +1179,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let static_r = self.universal_regions.fr_static;
         for ur in self.scc_values.universal_regions_outlived_by(r_scc) {
             let new_lub = self.universal_region_relations.postdom_upper_bound(lub, ur);
-            debug!("approx_universal_upper_bound: ur={:?} lub={:?} new_lub={:?}", ur, lub, new_lub);
+            debug!(?ur, ?lub, ?new_lub);
             // The upper bound of two non-static regions is static: this
             // means we know nothing about the relationship between these
             // two regions. Pick a 'better' one to use when constructing
@@ -1201,7 +1203,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             }
         }
 
-        debug!("approx_universal_upper_bound: r={:?} lub={:?}", r, lub);
+        debug!(?r, ?lub);
 
         lub
     }
@@ -1332,15 +1334,15 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     // Evaluate whether `sup_region: sub_region`.
-    #[instrument(skip(self), level = "debug")]
+    #[instrument(skip(self), level = "debug", ret)]
     fn eval_outlives(&self, sup_region: RegionVid, sub_region: RegionVid) -> bool {
         debug!(
-            "eval_outlives: sup_region's value = {:?} universal={:?}",
+            "sup_region's value = {:?} universal={:?}",
             self.region_value_str(sup_region),
             self.universal_regions.is_universal_region(sup_region),
         );
         debug!(
-            "eval_outlives: sub_region's value = {:?} universal={:?}",
+            "sub_region's value = {:?} universal={:?}",
             self.region_value_str(sub_region),
             self.universal_regions.is_universal_region(sub_region),
         );
@@ -1353,7 +1355,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // true if `'sup` outlives static.
         if !self.universe_compatible(sub_region_scc, sup_region_scc) {
             debug!(
-                "eval_outlives: sub universe `{sub_region_scc:?}` is not nameable \
+                "sub universe `{sub_region_scc:?}` is not nameable \
                 by super `{sup_region_scc:?}`, promoting to static",
             );
 
@@ -1374,9 +1376,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             });
 
         if !universal_outlives {
-            debug!(
-                "eval_outlives: returning false because sub region contains a universal region not present in super"
-            );
+            debug!("sub region contains a universal region not present in super");
             return false;
         }
 
@@ -1385,15 +1385,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         if self.universal_regions.is_universal_region(sup_region) {
             // Micro-opt: universal regions contain all points.
-            debug!(
-                "eval_outlives: returning true because super is universal and hence contains all points"
-            );
+            debug!("super is universal and hence contains all points");
             return true;
         }
 
-        let result = self.scc_values.contains_points(sup_region_scc, sub_region_scc);
-        debug!("returning {} because of comparison between points in sup/sub", result);
-        result
+        debug!("comparison between points in sup/sub");
+
+        self.scc_values.contains_points(sup_region_scc, sub_region_scc)
     }
 
     /// Once regions have been propagated, this method is used to see
@@ -1415,7 +1413,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// report them as errors.
     fn check_universal_regions(
         &self,
-        body: &Body<'tcx>,
         mut propagated_outlives_requirements: Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
         errors_buffer: &mut RegionErrors<'tcx>,
     ) {
@@ -1426,7 +1423,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     // they did not grow too large, accumulating any requirements
                     // for our caller into the `outlives_requirements` vector.
                     self.check_universal_region(
-                        body,
                         fr,
                         &mut propagated_outlives_requirements,
                         errors_buffer,
@@ -1467,7 +1463,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// report them as errors.
     fn check_polonius_subset_errors(
         &self,
-        body: &Body<'tcx>,
         mut propagated_outlives_requirements: Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
         errors_buffer: &mut RegionErrors<'tcx>,
         polonius_output: Rc<PoloniusOutput>,
@@ -1514,7 +1509,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             let propagated = self.try_propagate_universal_region_error(
                 *longer_fr,
                 *shorter_fr,
-                body,
                 &mut propagated_outlives_requirements,
             );
             if propagated == RegionRelationCheckResult::Error {
@@ -1554,13 +1548,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///
     /// Things that are to be propagated are accumulated into the
     /// `outlives_requirements` vector.
-    #[instrument(
-        skip(self, body, propagated_outlives_requirements, errors_buffer),
-        level = "debug"
-    )]
+    #[instrument(skip(self, propagated_outlives_requirements, errors_buffer), level = "debug")]
     fn check_universal_region(
         &self,
-        body: &Body<'tcx>,
         longer_fr: RegionVid,
         propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
         errors_buffer: &mut RegionErrors<'tcx>,
@@ -1583,7 +1573,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             if let RegionRelationCheckResult::Error = self.check_universal_region_relation(
                 longer_fr,
                 representative,
-                body,
                 propagated_outlives_requirements,
             ) {
                 errors_buffer.push(RegionErrorKind::RegionError {
@@ -1603,7 +1592,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             if let RegionRelationCheckResult::Error = self.check_universal_region_relation(
                 longer_fr,
                 shorter_fr,
-                body,
                 propagated_outlives_requirements,
             ) {
                 // We only report the first region error. Subsequent errors are hidden so as
@@ -1628,7 +1616,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         &self,
         longer_fr: RegionVid,
         shorter_fr: RegionVid,
-        body: &Body<'tcx>,
         propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
     ) -> RegionRelationCheckResult {
         // If it is known that `fr: o`, carry on.
@@ -1644,7 +1631,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             self.try_propagate_universal_region_error(
                 longer_fr,
                 shorter_fr,
-                body,
                 propagated_outlives_requirements,
             )
         }
@@ -1656,7 +1642,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         &self,
         longer_fr: RegionVid,
         shorter_fr: RegionVid,
-        body: &Body<'tcx>,
         propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
     ) -> RegionRelationCheckResult {
         if let Some(propagated_outlives_requirements) = propagated_outlives_requirements {
@@ -1668,7 +1653,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 debug!("try_propagate_universal_region_error: fr_minus={:?}", fr_minus);
 
                 let blame_span_category = self.find_outlives_blame_span(
-                    body,
                     longer_fr,
                     NllRegionVariableOrigin::FreeRegion,
                     shorter_fr,
@@ -1822,50 +1806,26 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
     pub(crate) fn retrieve_closure_constraint_info(
         &self,
-        _body: &Body<'tcx>,
-        constraint: &OutlivesConstraint<'tcx>,
-    ) -> BlameConstraint<'tcx> {
-        let loc = match constraint.locations {
-            Locations::All(span) => {
-                return BlameConstraint {
-                    category: constraint.category,
-                    from_closure: false,
-                    cause: ObligationCause::dummy_with_span(span),
-                    variance_info: constraint.variance_info,
-                };
+        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()
             }
-            Locations::Single(loc) => loc,
-        };
-
-        let opt_span_category =
-            self.closure_bounds_mapping[&loc].get(&(constraint.sup, constraint.sub));
-        opt_span_category
-            .map(|&(category, span)| BlameConstraint {
-                category,
-                from_closure: true,
-                cause: ObligationCause::dummy_with_span(span),
-                variance_info: constraint.variance_info,
-            })
-            .unwrap_or(BlameConstraint {
-                category: constraint.category,
-                from_closure: false,
-                cause: ObligationCause::dummy_with_span(constraint.span),
-                variance_info: constraint.variance_info,
-            })
+        }
     }
 
     /// Finds a good `ObligationCause` to blame for the fact that `fr1` outlives `fr2`.
     pub(crate) fn find_outlives_blame_span(
         &self,
-        body: &Body<'tcx>,
         fr1: RegionVid,
         fr1_origin: NllRegionVariableOrigin,
         fr2: RegionVid,
     ) -> (ConstraintCategory<'tcx>, ObligationCause<'tcx>) {
-        let BlameConstraint { category, cause, .. } =
-            self.best_blame_constraint(body, fr1, fr1_origin, |r| {
-                self.provides_universal_region(r, fr1, fr2)
-            });
+        let BlameConstraint { category, cause, .. } = self
+            .best_blame_constraint(fr1, fr1_origin, |r| self.provides_universal_region(r, fr1, fr2))
+            .0;
         (category, cause)
     }
 
@@ -1970,7 +1930,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     /// Finds some region R such that `fr1: R` and `R` is live at `elem`.
-    #[instrument(skip(self), level = "trace")]
+    #[instrument(skip(self), level = "trace", ret)]
     pub(crate) fn find_sub_region_live_at(&self, fr1: RegionVid, elem: Location) -> RegionVid {
         trace!(scc = ?self.constraint_sccs.scc(fr1));
         trace!(universe = ?self.scc_universes[self.constraint_sccs.scc(fr1)]);
@@ -2048,23 +2008,18 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// creating a constraint path that forces `R` to outlive
     /// `from_region`, and then finding the best choices within that
     /// path to blame.
+    #[instrument(level = "debug", skip(self, target_test))]
     pub(crate) fn best_blame_constraint(
         &self,
-        body: &Body<'tcx>,
         from_region: RegionVid,
         from_region_origin: NllRegionVariableOrigin,
         target_test: impl Fn(RegionVid) -> bool,
-    ) -> BlameConstraint<'tcx> {
-        debug!(
-            "best_blame_constraint(from_region={:?}, from_region_origin={:?})",
-            from_region, from_region_origin
-        );
-
+    ) -> (BlameConstraint<'tcx>, Vec<ExtraConstraintInfo>) {
         // Find all paths
         let (path, target_region) =
             self.find_constraint_paths_between_regions(from_region, target_test).unwrap();
         debug!(
-            "best_blame_constraint: path={:#?}",
+            "path={:#?}",
             path.iter()
                 .map(|c| format!(
                     "{:?} ({:?}: {:?})",
@@ -2075,6 +2030,18 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 .collect::<Vec<_>>()
         );
 
+        let mut extra_info = vec![];
+        for constraint in path.iter() {
+            let outlived = constraint.sub;
+            let Some(origin) = self.var_infos.get(outlived) else { continue; };
+            let RegionVariableOrigin::Nll(NllRegionVariableOrigin::Placeholder(p)) = origin.origin else { continue; };
+            debug!(?constraint, ?p);
+            let ConstraintCategory::Predicate(span) = constraint.category else { continue; };
+            extra_info.push(ExtraConstraintInfo::PlaceholderFromPredicate(span));
+            // We only want to point to one
+            break;
+        }
+
         // We try to avoid reporting a `ConstraintCategory::Predicate` as our best constraint.
         // Instead, we use it to produce an improved `ObligationCauseCode`.
         // FIXME - determine what we should do if we encounter multiple `ConstraintCategory::Predicate`
@@ -2100,23 +2067,33 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let mut categorized_path: Vec<BlameConstraint<'tcx>> = path
             .iter()
             .map(|constraint| {
-                if constraint.category == ConstraintCategory::ClosureBounds {
-                    self.retrieve_closure_constraint_info(body, &constraint)
-                } else {
-                    BlameConstraint {
-                        category: constraint.category,
-                        from_closure: false,
-                        cause: ObligationCause::new(
-                            constraint.span,
-                            CRATE_HIR_ID,
-                            cause_code.clone(),
-                        ),
-                        variance_info: constraint.variance_info,
-                    }
+                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,
                 }
             })
             .collect();
-        debug!("best_blame_constraint: categorized_path={:#?}", categorized_path);
+        debug!("categorized_path={:#?}", categorized_path);
 
         // To find the best span to cite, we first try to look for the
         // final constraint that is interesting and where the `sup` is
@@ -2214,10 +2191,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let best_choice =
             if blame_source { range.rev().find(find_region) } else { range.find(find_region) };
 
-        debug!(
-            "best_blame_constraint: best_choice={:?} blame_source={}",
-            best_choice, blame_source
-        );
+        debug!(?best_choice, ?blame_source, ?extra_info);
 
         if let Some(i) = best_choice {
             if let Some(next) = categorized_path.get(i + 1) {
@@ -2226,7 +2200,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 {
                     // The return expression is being influenced by the return type being
                     // impl Trait, point at the return type and not the return expr.
-                    return next.clone();
+                    return (next.clone(), extra_info);
                 }
             }
 
@@ -2246,7 +2220,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 }
             }
 
-            return categorized_path[i].clone();
+            return (categorized_path[i].clone(), extra_info);
         }
 
         // If that search fails, that is.. unusual. Maybe everything
@@ -2254,9 +2228,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // appears to be the most interesting point to report to the
         // user via an even more ad-hoc guess.
         categorized_path.sort_by(|p0, p1| p0.category.cmp(&p1.category));
-        debug!("best_blame_constraint: sorted_path={:#?}", categorized_path);
+        debug!("sorted_path={:#?}", categorized_path);
 
-        categorized_path.remove(0)
+        (categorized_path.remove(0), extra_info)
     }
 
     pub(crate) fn universe_info(&self, universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
@@ -2338,7 +2312,13 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
                              outlives_requirement={:?}",
                             region, outlived_region, outlives_requirement,
                         );
-                        ty::Binder::dummy(ty::OutlivesPredicate(region.into(), outlived_region))
+                        (
+                            ty::Binder::dummy(ty::OutlivesPredicate(
+                                region.into(),
+                                outlived_region,
+                            )),
+                            ConstraintCategory::BoringNoLocation,
+                        )
                     }
 
                     ClosureOutlivesSubject::Ty(ty) => {
@@ -2348,7 +2328,10 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
                              outlives_requirement={:?}",
                             ty, outlived_region, outlives_requirement,
                         );
-                        ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), outlived_region))
+                        (
+                            ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), outlived_region)),
+                            ConstraintCategory::BoringNoLocation,
+                        )
                     }
                 }
             })
@@ -2362,4 +2345,5 @@ pub struct BlameConstraint<'tcx> {
     pub from_closure: bool,
     pub cause: ObligationCause<'tcx>,
     pub variance_info: ty::VarianceDiagInfo<'tcx>,
+    pub outlives_constraint: OutlivesConstraint<'tcx>,
 }
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index d6712b6a4..9d088642f 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -16,6 +16,8 @@ use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
 use rustc_trait_selection::traits::TraitEngineExt as _;
 
+use crate::session_diagnostics::ConstNotUsedTraitAlias;
+
 use super::RegionInferenceContext;
 
 impl<'tcx> RegionInferenceContext<'tcx> {
@@ -58,7 +60,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// Calling `universal_upper_bound` for such a region gives `fr_fn_body`,
     /// which has no `external_name` in which case we use `'empty` as the
     /// region to pass to `infer_opaque_definition_from_instantiation`.
-    #[instrument(level = "debug", skip(self, infcx))]
+    #[instrument(level = "debug", skip(self, infcx), ret)]
     pub(crate) fn infer_opaque_types(
         &self,
         infcx: &InferCtxt<'_, 'tcx>,
@@ -107,7 +109,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         .iter()
                         .find(|ur_vid| self.eval_equal(vid, **ur_vid))
                         .and_then(|ur_vid| self.definitions[*ur_vid].external_name)
-                        .unwrap_or(infcx.tcx.lifetimes.re_root_empty),
+                        .unwrap_or(infcx.tcx.lifetimes.re_erased),
                     _ => region,
                 });
 
@@ -431,7 +433,7 @@ struct ReverseMapper<'tcx> {
 
     key: ty::OpaqueTypeKey<'tcx>,
     map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
-    map_missing_regions_to_empty: bool,
+    do_not_error: bool,
 
     /// initially `Some`, set to `None` once error has been reported
     hidden_ty: Option<Ty<'tcx>>,
@@ -448,29 +450,19 @@ impl<'tcx> ReverseMapper<'tcx> {
         hidden_ty: Ty<'tcx>,
         span: Span,
     ) -> Self {
-        Self {
-            tcx,
-            key,
-            map,
-            map_missing_regions_to_empty: false,
-            hidden_ty: Some(hidden_ty),
-            span,
-        }
+        Self { tcx, key, map, do_not_error: false, hidden_ty: Some(hidden_ty), span }
     }
 
-    fn fold_kind_mapping_missing_regions_to_empty(
-        &mut self,
-        kind: GenericArg<'tcx>,
-    ) -> GenericArg<'tcx> {
-        assert!(!self.map_missing_regions_to_empty);
-        self.map_missing_regions_to_empty = true;
+    fn fold_kind_no_missing_regions_error(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
+        assert!(!self.do_not_error);
+        self.do_not_error = true;
         let kind = kind.fold_with(self);
-        self.map_missing_regions_to_empty = false;
+        self.do_not_error = false;
         kind
     }
 
     fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
-        assert!(!self.map_missing_regions_to_empty);
+        assert!(!self.do_not_error);
         kind.fold_with(self)
     }
 }
@@ -494,9 +486,9 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
             ty::ReErased => return r,
 
             // The regions that we expect from borrow checking.
-            ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReEmpty(ty::UniverseIndex::ROOT) => {}
+            ty::ReEarlyBound(_) | ty::ReFree(_) => {}
 
-            ty::ReEmpty(_) | ty::RePlaceholder(_) | ty::ReVar(_) => {
+            ty::RePlaceholder(_) | ty::ReVar(_) => {
                 // All of the regions in the type should either have been
                 // erased by writeback, or mapped back to named regions by
                 // borrow checking.
@@ -508,7 +500,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
         match self.map.get(&r.into()).map(|k| k.unpack()) {
             Some(GenericArgKind::Lifetime(r1)) => r1,
             Some(u) => panic!("region mapped to unexpected kind: {:?}", u),
-            None if self.map_missing_regions_to_empty => self.tcx.lifetimes.re_root_empty,
+            None if self.do_not_error => self.tcx.lifetimes.re_static,
             None if generics.parent.is_some() => {
                 if let Some(hidden_ty) = self.hidden_ty.take() {
                     unexpected_hidden_region_diagnostic(
@@ -520,7 +512,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
                     )
                     .emit();
                 }
-                self.tcx.lifetimes.re_root_empty
+                self.tcx.lifetimes.re_static
             }
             None => {
                 self.tcx
@@ -572,7 +564,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
                 let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| {
                     if index < generics.parent_count {
                         // Accommodate missing regions in the parent kinds...
-                        self.fold_kind_mapping_missing_regions_to_empty(kind)
+                        self.fold_kind_no_missing_regions_error(kind)
                     } else {
                         // ...but not elsewhere.
                         self.fold_kind_normally(kind)
@@ -587,7 +579,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
                 let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| {
                     if index < generics.parent_count {
                         // Accommodate missing regions in the parent kinds...
-                        self.fold_kind_mapping_missing_regions_to_empty(kind)
+                        self.fold_kind_no_missing_regions_error(kind)
                     } else {
                         // ...but not elsewhere.
                         self.fold_kind_normally(kind)
@@ -639,17 +631,10 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
                     Some(GenericArgKind::Const(c1)) => c1,
                     Some(u) => panic!("const mapped to unexpected kind: {:?}", u),
                     None => {
-                        self.tcx
-                            .sess
-                            .struct_span_err(
-                                self.span,
-                                &format!(
-                                    "const parameter `{}` is part of concrete type but not \
-                                          used in parameter list for the `impl Trait` type alias",
-                                    ct
-                                ),
-                            )
-                            .emit();
+                        self.tcx.sess.emit_err(ConstNotUsedTraitAlias {
+                            ct: ct.to_string(),
+                            span: self.span,
+                        });
 
                         self.tcx().const_error(ct.ty())
                     }
diff --git a/compiler/rustc_borrowck/src/region_infer/values.rs b/compiler/rustc_borrowck/src/region_infer/values.rs
index c81ef10f7..de20a4bb4 100644
--- a/compiler/rustc_borrowck/src/region_infer/values.rs
+++ b/compiler/rustc_borrowck/src/region_infer/values.rs
@@ -25,7 +25,7 @@ impl RegionValueElements {
     pub(crate) fn new(body: &Body<'_>) -> Self {
         let mut num_points = 0;
         let statements_before_block: IndexVec<BasicBlock, usize> = body
-            .basic_blocks()
+            .basic_blocks
             .iter()
             .map(|block_data| {
                 let v = num_points;
@@ -37,7 +37,7 @@ impl RegionValueElements {
         debug!("RegionValueElements: num_points={:#?}", num_points);
 
         let mut basic_blocks = IndexVec::with_capacity(num_points);
-        for (bb, bb_data) in body.basic_blocks().iter_enumerated() {
+        for (bb, bb_data) in body.basic_blocks.iter_enumerated() {
             basic_blocks.extend((0..=bb_data.statements.len()).map(|_| bb));
         }
 
diff --git a/compiler/rustc_borrowck/src/renumber.rs b/compiler/rustc_borrowck/src/renumber.rs
index 7a8ce621c..63b2088f7 100644
--- a/compiler/rustc_borrowck/src/renumber.rs
+++ b/compiler/rustc_borrowck/src/renumber.rs
@@ -2,6 +2,7 @@ use rustc_index::vec::IndexVec;
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_middle::mir::visit::{MutVisitor, TyContext};
 use rustc_middle::mir::{Body, Location, Promoted};
+use rustc_middle::mir::{Constant, ConstantKind};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
 
@@ -37,6 +38,21 @@ where
     })
 }
 
+// FIXME(valtrees): This function is necessary because `fold_regions`
+// panics for mir constants in the visitor.
+//
+// Once `visit_mir_constant` is removed we can also remove this function
+// and just use `renumber_regions`.
+fn renumber_regions_in_mir_constant<'tcx>(
+    infcx: &InferCtxt<'_, 'tcx>,
+    value: ConstantKind<'tcx>,
+) -> ConstantKind<'tcx> {
+    infcx.tcx.super_fold_regions(value, |_region, _depth| {
+        let origin = NllRegionVariableOrigin::Existential { from_forall: false };
+        infcx.next_nll_region_var(origin)
+    })
+}
+
 struct NllVisitor<'a, 'tcx> {
     infcx: &'a InferCtxt<'a, 'tcx>,
 }
@@ -48,6 +64,13 @@ impl<'a, 'tcx> NllVisitor<'a, 'tcx> {
     {
         renumber_regions(self.infcx, value)
     }
+
+    fn renumber_regions_in_mir_constant(
+        &mut self,
+        value: ConstantKind<'tcx>,
+    ) -> ConstantKind<'tcx> {
+        renumber_regions_in_mir_constant(self.infcx, value)
+    }
 }
 
 impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
@@ -77,7 +100,10 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
         debug!(?region);
     }
 
-    fn visit_const(&mut self, constant: &mut ty::Const<'tcx>, _location: Location) {
-        *constant = self.renumber_regions(*constant);
+    #[instrument(skip(self), level = "debug")]
+    fn visit_constant(&mut self, constant: &mut Constant<'tcx>, _location: Location) {
+        let literal = constant.literal;
+        constant.literal = self.renumber_regions_in_mir_constant(literal);
+        debug!("constant: {:#?}", constant);
     }
 }
diff --git a/compiler/rustc_borrowck/src/session_diagnostics.rs b/compiler/rustc_borrowck/src/session_diagnostics.rs
index 895723d44..5d750c6ca 100644
--- a/compiler/rustc_borrowck/src/session_diagnostics.rs
+++ b/compiler/rustc_borrowck/src/session_diagnostics.rs
@@ -1,9 +1,12 @@
-use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
+use rustc_errors::{IntoDiagnosticArg, MultiSpan};
+use rustc_macros::{LintDiagnostic, SessionDiagnostic, SessionSubdiagnostic};
 use rustc_middle::ty::Ty;
 use rustc_span::Span;
 
+use crate::diagnostics::RegionName;
+
 #[derive(SessionDiagnostic)]
-#[error(borrowck::move_unsized, code = "E0161")]
+#[diag(borrowck::move_unsized, code = "E0161")]
 pub(crate) struct MoveUnsized<'tcx> {
     pub ty: Ty<'tcx>,
     #[primary_span]
@@ -12,7 +15,7 @@ pub(crate) struct MoveUnsized<'tcx> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(borrowck::higher_ranked_lifetime_error)]
+#[diag(borrowck::higher_ranked_lifetime_error)]
 pub(crate) struct HigherRankedLifetimeError {
     #[subdiagnostic]
     pub cause: Option<HigherRankedErrorCause>,
@@ -29,16 +32,128 @@ pub(crate) enum HigherRankedErrorCause {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(borrowck::higher_ranked_subtype_error)]
+#[diag(borrowck::higher_ranked_subtype_error)]
 pub(crate) struct HigherRankedSubtypeError {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(borrowck::generic_does_not_live_long_enough)]
+#[diag(borrowck::generic_does_not_live_long_enough)]
 pub(crate) struct GenericDoesNotLiveLongEnough {
     pub kind: String,
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(borrowck::var_does_not_need_mut)]
+pub(crate) struct VarNeedNotMut {
+    #[suggestion_short(applicability = "machine-applicable", code = "")]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(borrowck::const_not_used_in_type_alias)]
+pub(crate) struct ConstNotUsedTraitAlias {
+    pub ct: String,
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(borrowck::var_cannot_escape_closure)]
+#[note]
+#[note(borrowck::cannot_escape)]
+pub(crate) struct FnMutError {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub ty_err: FnMutReturnTypeErr,
+}
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum VarHereDenote {
+    #[label(borrowck::var_here_captured)]
+    Captured {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(borrowck::var_here_defined)]
+    Defined {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(borrowck::closure_inferred_mut)]
+    FnMutInferred {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum FnMutReturnTypeErr {
+    #[label(borrowck::returned_closure_escaped)]
+    ReturnClosure {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(borrowck::returned_async_block_escaped)]
+    ReturnAsyncBlock {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(borrowck::returned_ref_escaped)]
+    ReturnRef {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(borrowck::lifetime_constraints_error)]
+pub(crate) struct LifetimeOutliveErr {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum LifetimeReturnCategoryErr<'a> {
+    #[label(borrowck::returned_lifetime_wrong)]
+    WrongReturn {
+        #[primary_span]
+        span: Span,
+        mir_def_name: &'a str,
+        outlived_fr_name: RegionName,
+        fr_name: &'a RegionName,
+    },
+    #[label(borrowck::returned_lifetime_short)]
+    ShortReturn {
+        #[primary_span]
+        span: Span,
+        category_desc: &'static str,
+        free_region_name: &'a RegionName,
+        outlived_fr_name: RegionName,
+    },
+}
+
+impl IntoDiagnosticArg for &RegionName {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        format!("{}", self).into_diagnostic_arg()
+    }
+}
+
+impl IntoDiagnosticArg for RegionName {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        format!("{}", self).into_diagnostic_arg()
+    }
+}
+
+#[derive(SessionSubdiagnostic)]
+pub(crate) enum RequireStaticErr {
+    #[note(borrowck::used_impl_require_static)]
+    UsedImpl {
+        #[primary_span]
+        multi_span: MultiSpan,
+    },
+}
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index 6cfe5efb6..9271a2f4d 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -24,8 +24,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     /// **Any `rustc_infer::infer` operations that might generate region
     /// constraints should occur within this method so that those
     /// constraints can be properly localized!**
-    #[instrument(skip(self, category, op), level = "trace")]
-    pub(super) fn fully_perform_op<R, Op>(
+    #[instrument(skip(self, op), level = "trace")]
+    pub(super) fn fully_perform_op<R: fmt::Debug, Op>(
         &mut self,
         locations: Locations,
         category: ConstraintCategory<'tcx>,
@@ -39,6 +39,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
         let TypeOpOutput { output, constraints, error_info } = op.fully_perform(self.infcx)?;
 
+        debug!(?output, ?constraints);
+
         if let Some(data) = constraints {
             self.push_region_constraints(locations, category, data);
         }
@@ -90,17 +92,19 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         locations: Locations,
         category: ConstraintCategory<'tcx>,
     ) {
-        self.prove_predicates(
-            Some(ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
+        self.prove_predicate(
+            ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
                 trait_ref,
                 constness: ty::BoundConstness::NotConst,
                 polarity: ty::ImplPolarity::Positive,
-            }))),
+            }))
+            .to_predicate(self.tcx()),
             locations,
             category,
         );
     }
 
+    #[instrument(level = "debug", skip(self))]
     pub(super) fn normalize_and_prove_instantiated_predicates(
         &mut self,
         // Keep this parameter for now, in case we start using
@@ -115,8 +119,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             .zip(instantiated_predicates.spans.into_iter())
         {
             debug!(?predicate);
-            let predicate = self.normalize(predicate, locations);
-            self.prove_predicate(predicate, locations, ConstraintCategory::Predicate(span));
+            let category = ConstraintCategory::Predicate(span);
+            let predicate = self.normalize_with_category(predicate, locations, category);
+            self.prove_predicate(predicate, locations, category);
         }
     }
 
@@ -152,15 +157,27 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         })
     }
 
-    #[instrument(skip(self), level = "debug")]
     pub(super) fn normalize<T>(&mut self, value: T, location: impl NormalizeLocation) -> T
     where
         T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,
     {
+        self.normalize_with_category(value, location, ConstraintCategory::Boring)
+    }
+
+    #[instrument(skip(self), level = "debug")]
+    pub(super) fn normalize_with_category<T>(
+        &mut self,
+        value: T,
+        location: impl NormalizeLocation,
+        category: ConstraintCategory<'tcx>,
+    ) -> T
+    where
+        T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,
+    {
         let param_env = self.param_env;
         self.fully_perform_op(
             location.to_locations(),
-            ConstraintCategory::Boring,
+            category,
             param_env.and(type_op::normalize::Normalize::new(value)),
         )
         .unwrap_or_else(|NoSolution| {
diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
index 167960918..71eae0583 100644
--- a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
+++ b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -6,7 +6,7 @@ use rustc_infer::infer::region_constraints::{GenericKind, VerifyBound};
 use rustc_infer::infer::{self, InferCtxt, SubregionOrigin};
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::subst::GenericArgKind;
-use rustc_middle::ty::TypeVisitable;
+use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::{Span, DUMMY_SP};
 
@@ -86,7 +86,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         }
     }
 
-    pub(super) fn convert(&mut self, query_constraint: &QueryOutlivesConstraint<'tcx>) {
+    fn convert(&mut self, query_constraint: &QueryOutlivesConstraint<'tcx>) {
         debug!("generate: constraints at: {:#?}", self.locations);
 
         // Extract out various useful fields we'll need below.
@@ -98,34 +98,25 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         // 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.no_bound_vars().unwrap_or_else(|| {
-            bug!("query_constraint {:?} contained bound vars", query_constraint,);
-        });
+        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;
 
         match k1.unpack() {
             GenericArgKind::Lifetime(r1) => {
                 let r1_vid = self.to_region_vid(r1);
                 let r2_vid = self.to_region_vid(r2);
-                self.add_outlives(r1_vid, r2_vid);
+                self.add_outlives(r1_vid, r2_vid, constraint_category);
             }
 
-            GenericArgKind::Type(mut t1) => {
+            GenericArgKind::Type(t1) => {
                 // we don't actually use this for anything, but
                 // the `TypeOutlives` code needs an origin.
                 let origin = infer::RelateParamBound(DUMMY_SP, t1, None);
 
-                // Placeholder regions need to be converted now because it may
-                // create new region variables, which can't be done later when
-                // verifying these bounds.
-                if t1.has_placeholders() {
-                    t1 = tcx.fold_regions(t1, |r, _| match *r {
-                        ty::RePlaceholder(placeholder) => {
-                            self.constraints.placeholder_region(self.infcx, placeholder)
-                        }
-                        _ => r,
-                    });
-                }
-
                 TypeOutlives::new(
                     &mut *self,
                     tcx,
@@ -133,7 +124,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
                     Some(implicit_region_bound),
                     param_env,
                 )
-                .type_must_outlive(origin, t1, r2);
+                .type_must_outlive(origin, t1, r2, constraint_category);
             }
 
             GenericArgKind::Const(_) => {
@@ -143,6 +134,25 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         }
     }
 
+    /// Placeholder regions need to be converted eagerly because it may
+    /// create new region variables, which we must not do when verifying
+    /// our region bounds.
+    ///
+    /// FIXME: This should get removed once higher ranked region obligations
+    /// are dealt with during trait solving.
+    fn replace_placeholders_with_nll<T: TypeFoldable<'tcx>>(&mut self, value: T) -> T {
+        if value.has_placeholders() {
+            self.tcx.fold_regions(value, |r, _| match *r {
+                ty::RePlaceholder(placeholder) => {
+                    self.constraints.placeholder_region(self.infcx, placeholder)
+                }
+                _ => r,
+            })
+        } else {
+            value
+        }
+    }
+
     fn verify_to_type_test(
         &mut self,
         generic_kind: GenericKind<'tcx>,
@@ -150,7 +160,6 @@ 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 }
     }
 
@@ -162,10 +171,19 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         }
     }
 
-    fn add_outlives(&mut self, sup: ty::RegionVid, sub: ty::RegionVid) {
+    fn add_outlives(
+        &mut self,
+        sup: ty::RegionVid,
+        sub: ty::RegionVid,
+        category: ConstraintCategory<'tcx>,
+    ) {
+        let category = match self.category {
+            ConstraintCategory::Boring | ConstraintCategory::BoringNoLocation => category,
+            _ => self.category,
+        };
         self.constraints.outlives_constraints.push(OutlivesConstraint {
             locations: self.locations,
-            category: self.category,
+            category,
             span: self.span,
             sub,
             sup,
@@ -185,10 +203,11 @@ impl<'a, 'b, 'tcx> TypeOutlivesDelegate<'tcx> for &'a mut ConstraintConversion<'
         _origin: SubregionOrigin<'tcx>,
         a: ty::Region<'tcx>,
         b: ty::Region<'tcx>,
+        constraint_category: ConstraintCategory<'tcx>,
     ) {
         let b = self.to_region_vid(b);
         let a = self.to_region_vid(a);
-        self.add_outlives(b, a);
+        self.add_outlives(b, a, constraint_category);
     }
 
     fn push_verify(
@@ -198,6 +217,8 @@ impl<'a, 'b, 'tcx> TypeOutlivesDelegate<'tcx> for &'a mut ConstraintConversion<'
         a: ty::Region<'tcx>,
         bound: VerifyBound<'tcx>,
     ) {
+        let kind = self.replace_placeholders_with_nll(kind);
+        let bound = self.replace_placeholders_with_nll(bound);
         let type_test = self.verify_to_type_test(kind, a, bound);
         self.add_type_test(type_test);
     }
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 cc0318ede..f1b1c33a1 100644
--- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
+++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
@@ -1,5 +1,5 @@
 use rustc_data_structures::frozen::Frozen;
-use rustc_data_structures::transitive_relation::TransitiveRelation;
+use rustc_data_structures::transitive_relation::{TransitiveRelation, TransitiveRelationBuilder};
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_infer::infer::outlives;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
@@ -61,25 +61,13 @@ pub(crate) fn create<'tcx>(
         constraints,
         universal_regions: universal_regions.clone(),
         region_bound_pairs: Default::default(),
-        relations: UniversalRegionRelations {
-            universal_regions: universal_regions.clone(),
-            outlives: Default::default(),
-            inverse_outlives: Default::default(),
-        },
+        outlives: Default::default(),
+        inverse_outlives: Default::default(),
     }
     .create()
 }
 
 impl UniversalRegionRelations<'_> {
-    /// Records in the `outlives_relation` (and
-    /// `inverse_outlives_relation`) that `fr_a: fr_b`. Invoked by the
-    /// builder below.
-    fn relate_universal_regions(&mut self, fr_a: RegionVid, fr_b: RegionVid) {
-        debug!("relate_universal_regions: fr_a={:?} outlives fr_b={:?}", fr_a, fr_b);
-        self.outlives.add(fr_a, fr_b);
-        self.inverse_outlives.add(fr_b, fr_a);
-    }
-
     /// Given two universal regions, returns the postdominating
     /// upper-bound (effectively the least upper bound).
     ///
@@ -216,11 +204,20 @@ struct UniversalRegionRelationsBuilder<'this, 'tcx> {
     constraints: &'this mut MirTypeckRegionConstraints<'tcx>,
 
     // outputs:
-    relations: UniversalRegionRelations<'tcx>,
+    outlives: TransitiveRelationBuilder<RegionVid>,
+    inverse_outlives: TransitiveRelationBuilder<RegionVid>,
     region_bound_pairs: RegionBoundPairs<'tcx>,
 }
 
 impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
+    /// Records in the `outlives_relation` (and
+    /// `inverse_outlives_relation`) that `fr_a: fr_b`.
+    fn relate_universal_regions(&mut self, fr_a: RegionVid, fr_b: RegionVid) {
+        debug!("relate_universal_regions: fr_a={:?} outlives fr_b={:?}", fr_a, fr_b);
+        self.outlives.add(fr_a, fr_b);
+        self.inverse_outlives.add(fr_b, fr_a);
+    }
+
     pub(crate) fn create(mut self) -> CreateResult<'tcx> {
         let unnormalized_input_output_tys = self
             .universal_regions
@@ -242,10 +239,9 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
         let constraint_sets: Vec<_> = unnormalized_input_output_tys
             .flat_map(|ty| {
                 debug!("build: input_or_output={:?}", ty);
-                // We only add implied bounds for the normalized type as the unnormalized
-                // type may not actually get checked by the caller.
-                //
-                // Can otherwise be unsound, see #91068.
+                // We add implied bounds from both the unnormalized and normalized ty.
+                // See issue #87748
+                let constraints_implied1 = self.add_implied_bounds(ty);
                 let TypeOpOutput { output: norm_ty, constraints: constraints1, .. } = self
                     .param_env
                     .and(type_op::normalize::Normalize::new(ty))
@@ -269,13 +265,14 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
                 // }
                 // impl Foo for () {
                 //   type Bar = ();
-                //   fn foo(&self) ->&() {}
+                //   fn foo(&self) -> &() {}
                 // }
                 // ```
                 // Both &Self::Bar and &() are WF
-                let constraints_implied = self.add_implied_bounds(norm_ty);
+                let constraints_implied2 =
+                    if ty != norm_ty { self.add_implied_bounds(norm_ty) } else { None };
                 normalized_inputs_and_output.push(norm_ty);
-                constraints1.into_iter().chain(constraints_implied)
+                constraints1.into_iter().chain(constraints_implied1).chain(constraints_implied2)
             })
             .collect();
 
@@ -292,9 +289,9 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
         let fr_fn_body = self.universal_regions.fr_fn_body;
         for fr in self.universal_regions.universal_regions() {
             debug!("build: relating free region {:?} to itself and to 'static", fr);
-            self.relations.relate_universal_regions(fr, fr);
-            self.relations.relate_universal_regions(fr_static, fr);
-            self.relations.relate_universal_regions(fr, fr_fn_body);
+            self.relate_universal_regions(fr, fr);
+            self.relate_universal_regions(fr_static, fr);
+            self.relate_universal_regions(fr, fr_fn_body);
         }
 
         for data in &constraint_sets {
@@ -313,7 +310,11 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
         }
 
         CreateResult {
-            universal_region_relations: Frozen::freeze(self.relations),
+            universal_region_relations: Frozen::freeze(UniversalRegionRelations {
+                universal_regions: self.universal_regions,
+                outlives: self.outlives.freeze(),
+                inverse_outlives: self.inverse_outlives.freeze(),
+            }),
             region_bound_pairs: self.region_bound_pairs,
             normalized_inputs_and_output,
         }
@@ -346,17 +347,10 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
 
             match outlives_bound {
                 OutlivesBound::RegionSubRegion(r1, r2) => {
-                    // `where Type:` is lowered to `where Type: 'empty` so that
-                    // we check `Type` is well formed, but there's no use for
-                    // this bound here.
-                    if r1.is_empty() {
-                        return;
-                    }
-
                     // The bound says that `r1 <= r2`; we store `r2: r1`.
                     let r1 = self.universal_regions.to_region_vid(r1);
                     let r2 = self.universal_regions.to_region_vid(r2);
-                    self.relations.relate_universal_regions(r2, r1);
+                    self.relate_universal_regions(r2, r1);
                 }
 
                 OutlivesBound::RegionSubParam(r_a, param_b) => {
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index d32b1edcd..3713ec3f5 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -30,8 +30,9 @@ use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef, UserSubsts};
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{
-    self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, OpaqueHiddenType,
-    OpaqueTypeKey, RegionVid, ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,
+    self, Binder, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, Dynamic,
+    OpaqueHiddenType, OpaqueTypeKey, RegionVid, ToPredicate, Ty, TyCtxt, UserType,
+    UserTypeAnnotationIndex,
 };
 use rustc_span::def_id::CRATE_DEF_ID;
 use rustc_span::{Span, DUMMY_SP};
@@ -178,97 +179,15 @@ pub(crate) fn type_check<'mir, 'tcx>(
         upvars,
     };
 
-    let opaque_type_values = type_check_internal(
+    let mut checker = TypeChecker::new(
         infcx,
-        param_env,
         body,
-        promoted,
+        param_env,
         &region_bound_pairs,
         implicit_region_bound,
         &mut borrowck_context,
-        |mut cx| {
-            debug!("inside extra closure of type_check_internal");
-            cx.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output);
-            liveness::generate(
-                &mut cx,
-                body,
-                elements,
-                flow_inits,
-                move_data,
-                location_table,
-                use_polonius,
-            );
-
-            translate_outlives_facts(&mut cx);
-            let opaque_type_values =
-                infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
-
-            opaque_type_values
-                .into_iter()
-                .map(|(opaque_type_key, decl)| {
-                    cx.fully_perform_op(
-                        Locations::All(body.span),
-                        ConstraintCategory::OpaqueType,
-                        CustomTypeOp::new(
-                            |infcx| {
-                                infcx.register_member_constraints(
-                                    param_env,
-                                    opaque_type_key,
-                                    decl.hidden_type.ty,
-                                    decl.hidden_type.span,
-                                );
-                                Ok(InferOk { value: (), obligations: vec![] })
-                            },
-                            || "opaque_type_map".to_string(),
-                        ),
-                    )
-                    .unwrap();
-                    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_infer_types_or_consts() {
-                        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();
-                    }
-
-                    (opaque_type_key, (hidden_type, decl.origin))
-                })
-                .collect()
-        },
     );
 
-    MirTypeckResults { constraints, universal_region_relations, opaque_type_values }
-}
-
-#[instrument(
-    skip(infcx, body, promoted, region_bound_pairs, borrowck_context, extra),
-    level = "debug"
-)]
-fn type_check_internal<'a, 'tcx, R>(
-    infcx: &'a InferCtxt<'a, 'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    body: &'a Body<'tcx>,
-    promoted: &'a IndexVec<Promoted, Body<'tcx>>,
-    region_bound_pairs: &'a RegionBoundPairs<'tcx>,
-    implicit_region_bound: ty::Region<'tcx>,
-    borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>,
-    extra: impl FnOnce(TypeChecker<'a, 'tcx>) -> R,
-) -> R {
-    debug!("body: {:#?}", body);
-    let mut checker = TypeChecker::new(
-        infcx,
-        body,
-        param_env,
-        region_bound_pairs,
-        implicit_region_bound,
-        borrowck_context,
-    );
     let errors_reported = {
         let mut verifier = TypeVerifier::new(&mut checker, promoted);
         verifier.visit_body(&body);
@@ -280,7 +199,56 @@ fn type_check_internal<'a, 'tcx, R>(
         checker.typeck_mir(body);
     }
 
-    extra(checker)
+    checker.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output);
+    liveness::generate(
+        &mut checker,
+        body,
+        elements,
+        flow_inits,
+        move_data,
+        location_table,
+        use_polonius,
+    );
+
+    translate_outlives_facts(&mut checker);
+    let opaque_type_values = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
+
+    let opaque_type_values = opaque_type_values
+        .into_iter()
+        .map(|(opaque_type_key, decl)| {
+            checker
+                .fully_perform_op(
+                    Locations::All(body.span),
+                    ConstraintCategory::OpaqueType,
+                    CustomTypeOp::new(
+                        |infcx| {
+                            infcx.register_member_constraints(
+                                param_env,
+                                opaque_type_key,
+                                decl.hidden_type.ty,
+                                decl.hidden_type.span,
+                            );
+                            Ok(InferOk { value: (), obligations: vec![] })
+                        },
+                        || "opaque_type_map".to_string(),
+                    ),
+                )
+                .unwrap();
+            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_infer_types_or_consts() {
+                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();
+            }
+
+            (opaque_type_key, (hidden_type, decl.origin))
+        })
+        .collect();
+
+    MirTypeckResults { constraints, universal_region_relations, opaque_type_values }
 }
 
 fn translate_outlives_facts(typeck: &mut TypeChecker<'_, '_>) {
@@ -344,6 +312,8 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
     }
 
     fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
+        debug!(?constant, ?location, "visit_constant");
+
         self.super_constant(constant, location);
         let ty = self.sanitize_type(constant, constant.literal.ty());
 
@@ -387,11 +357,15 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
             let tcx = self.tcx();
             let maybe_uneval = match constant.literal {
                 ConstantKind::Ty(ct) => match ct.kind() {
-                    ty::ConstKind::Unevaluated(uv) => Some(uv),
+                    ty::ConstKind::Unevaluated(_) => {
+                        bug!("should not encounter unevaluated ConstantKind::Ty here, got {:?}", ct)
+                    }
                     _ => None,
                 },
+                ConstantKind::Unevaluated(uv, _) => Some(uv),
                 _ => None,
             };
+
             if let Some(uv) = maybe_uneval {
                 if let Some(promoted) = uv.promoted {
                     let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>,
@@ -1076,6 +1050,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             let CanonicalUserTypeAnnotation { span, ref user_ty, inferred_ty } = *user_annotation;
             let inferred_ty = self.normalize(inferred_ty, Locations::All(span));
             let annotation = self.instantiate_canonical_with_fresh_inference_vars(span, user_ty);
+            debug!(?annotation);
             match annotation {
                 UserType::Ty(mut ty) => {
                     ty = self.normalize(ty, Locations::All(span));
@@ -1334,12 +1309,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping {
-                ..
-            }) => span_bug!(
-                stmt.source_info.span,
-                "Unexpected StatementKind::CopyNonOverlapping, should only appear after lowering_intrinsics",
-            ),
+            StatementKind::Intrinsic(box ref kind) => match kind {
+                NonDivergingIntrinsic::Assume(op) => self.check_operand(op, location),
+                NonDivergingIntrinsic::CopyNonOverlapping(..) => span_bug!(
+                    stmt.source_info.span,
+                    "Unexpected NonDivergingIntrinsic::CopyNonOverlapping, should only appear after lowering_intrinsics",
+                ),
+            },
             StatementKind::FakeRead(..)
             | StatementKind::StorageLive(..)
             | StatementKind::StorageDead(..)
@@ -1448,9 +1424,14 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     ))
                 });
                 debug!(?sig);
-                let sig = self.normalize(sig, term_location);
-                self.check_call_dest(body, term, &sig, *destination, target, term_location);
-
+                // IMPORTANT: We have to prove well formed for the function signature before
+                // we normalize it, as otherwise types like `<&'a &'b () as Trait>::Assoc`
+                // get normalized away, causing us to ignore the `'b: 'a` bound used by the function.
+                //
+                // Normalization results in a well formed type if the input is well formed, so we
+                // don't have to check it twice.
+                //
+                // See #91068 for an example.
                 self.prove_predicates(
                     sig.inputs_and_output
                         .iter()
@@ -1458,6 +1439,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     term_location.to_locations(),
                     ConstraintCategory::Boring,
                 );
+                let sig = self.normalize(sig, 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
@@ -1834,14 +1817,14 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     }
 
     fn check_operand(&mut self, op: &Operand<'tcx>, location: Location) {
+        debug!(?op, ?location, "check_operand");
+
         if let Operand::Constant(constant) = op {
             let maybe_uneval = match constant.literal {
-                ConstantKind::Ty(ct) => match ct.kind() {
-                    ty::ConstKind::Unevaluated(uv) => Some(uv),
-                    _ => None,
-                },
-                _ => None,
+                ConstantKind::Val(..) | ConstantKind::Ty(_) => None,
+                ConstantKind::Unevaluated(uv, _) => Some(uv),
             };
+
             if let Some(uv) = maybe_uneval {
                 if uv.promoted.is_none() {
                     let tcx = self.tcx();
@@ -1904,7 +1887,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 }
             }
 
-            &Rvalue::NullaryOp(_, ty) => {
+            &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, &[]),
@@ -2033,6 +2016,36 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         );
                     }
 
+                    CastKind::DynStar => {
+                        // get the constraints from the target type (`dyn* Clone`)
+                        //
+                        // apply them to prove that the source type `Foo` implements `Clone` etc
+                        let (existential_predicates, region) = match ty.kind() {
+                            Dynamic(predicates, region, ty::DynStar) => (predicates, region),
+                            _ => panic!("Invalid dyn* cast_ty"),
+                        };
+
+                        let self_ty = op.ty(body, tcx);
+
+                        self.prove_predicates(
+                            existential_predicates
+                                .iter()
+                                .map(|predicate| predicate.with_self_ty(tcx, self_ty)),
+                            location.to_locations(),
+                            ConstraintCategory::Cast,
+                        );
+
+                        let outlives_predicate =
+                            tcx.mk_predicate(Binder::dummy(ty::PredicateKind::TypeOutlives(
+                                ty::OutlivesPredicate(self_ty, *region),
+                            )));
+                        self.prove_predicate(
+                            outlives_predicate,
+                            location.to_locations(),
+                            ConstraintCategory::Cast,
+                        );
+                    }
+
                     CastKind::Pointer(PointerCast::MutToConstPointer) => {
                         let ty::RawPtr(ty::TypeAndMut {
                             ty: ty_from,
@@ -2584,7 +2597,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 .enumerate()
                 .filter_map(|(idx, constraint)| {
                     let ty::OutlivesPredicate(k1, r2) =
-                        constraint.no_bound_vars().unwrap_or_else(|| {
+                        constraint.0.no_bound_vars().unwrap_or_else(|| {
                             bug!("query_constraint {:?} contained bound vars", constraint,);
                         });
 
@@ -2659,7 +2672,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             self.check_local(&body, local, local_decl);
         }
 
-        for (block, block_data) in body.basic_blocks().iter_enumerated() {
+        for (block, block_data) in body.basic_blocks.iter_enumerated() {
             let mut location = Location { block, statement_index: 0 };
             for stmt in &block_data.statements {
                 if !stmt.source_info.span.is_dummy() {
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 2a7713bc4..8cf9ed53d 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -54,13 +54,6 @@ pub struct UniversalRegions<'tcx> {
     /// The total number of universal region variables instantiated.
     num_universals: usize,
 
-    /// A special region variable created for the `'empty(U0)` region.
-    /// Note that this is **not** a "universal" region, as it doesn't
-    /// represent a universally bound placeholder or any such thing.
-    /// But we do create it here in this type because it's a useful region
-    /// to have around in a few limited cases.
-    pub root_empty: RegionVid,
-
     /// The "defining" type for this function, with all universal
     /// regions instantiated. For a closure or generator, this is the
     /// closure type, but for a top-level function it's the `FnDef`.
@@ -323,11 +316,7 @@ impl<'tcx> UniversalRegions<'tcx> {
 
     /// See `UniversalRegionIndices::to_region_vid`.
     pub fn to_region_vid(&self, r: ty::Region<'tcx>) -> RegionVid {
-        if let ty::ReEmpty(ty::UniverseIndex::ROOT) = *r {
-            self.root_empty
-        } else {
-            self.indices.to_region_vid(r)
-        }
+        self.indices.to_region_vid(r)
     }
 
     /// As part of the NLL unit tests, you can annotate a function with
@@ -501,16 +490,10 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             _ => None,
         };
 
-        let root_empty = self
-            .infcx
-            .next_nll_region_var(NllRegionVariableOrigin::Existential { from_forall: true })
-            .to_region_vid();
-
         UniversalRegions {
             indices,
             fr_static,
             fr_fn_body,
-            root_empty,
             first_extern_index,
             first_local_index,
             num_universals,
@@ -768,10 +751,9 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
         mir_def_id: LocalDefId,
         indices: &mut UniversalRegionIndices<'tcx>,
     ) {
-        debug!("replace_late_bound_regions_with_nll_infer_vars(mir_def_id={:?})", mir_def_id);
         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| {
-            debug!("replace_late_bound_regions_with_nll_infer_vars: r={:?}", r);
+            debug!(?r);
             if !indices.indices.contains_key(&r) {
                 let region_vid = self.next_nll_region_var(FR);
                 debug!(?region_vid);