diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index d0e0203bf8c44..ea3602e8a056a 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -495,8 +495,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     }
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // For existential, regions, nothing to do.
                 }
             }
@@ -1410,8 +1409,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     self.check_bound_universal_region(fr, placeholder, errors_buffer);
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // nothing to check here
                 }
             }
@@ -1513,8 +1511,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     self.check_bound_universal_region(fr, placeholder, errors_buffer);
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // nothing to check here
                 }
             }
@@ -1788,9 +1785,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 universe1.cannot_name(placeholder.universe)
             }
 
-            NllRegionVariableOrigin::RootEmptyRegion
-            | NllRegionVariableOrigin::FreeRegion
-            | NllRegionVariableOrigin::Existential { .. } => false,
+            NllRegionVariableOrigin::FreeRegion | NllRegionVariableOrigin::Existential { .. } => {
+                false
+            }
         }
     }
 
@@ -2152,8 +2149,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let blame_source = match from_region_origin {
             NllRegionVariableOrigin::FreeRegion
             | NllRegionVariableOrigin::Existential { from_forall: false } => true,
-            NllRegionVariableOrigin::RootEmptyRegion
-            | NllRegionVariableOrigin::Placeholder(_)
+            NllRegionVariableOrigin::Placeholder(_)
             | NllRegionVariableOrigin::Existential { from_forall: true } => false,
         };
 
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index d129e8454265b..7c1fa28b8dfcc 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -1,11 +1,20 @@
+use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::vec_map::VecMap;
 use rustc_hir::def_id::DefId;
 use rustc_hir::OpaqueTyOrigin;
+use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
 use rustc_infer::infer::InferCtxt;
+use rustc_infer::infer::TyCtxtInferExt as _;
+use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine};
+use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts};
+use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{
-    self, OpaqueHiddenType, OpaqueTypeKey, TyCtxt, TypeFoldable, TypeVisitable,
+    self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt, TypeFoldable,
 };
-use rustc_trait_selection::opaque_types::InferCtxtExt;
+use rustc_span::Span;
+use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
+use rustc_trait_selection::traits::TraitEngineExt as _;
 
 use super::RegionInferenceContext;
 
@@ -173,3 +182,474 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         })
     }
 }
+
+pub trait InferCtxtExt<'tcx> {
+    fn infer_opaque_definition_from_instantiation(
+        &self,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        instantiated_ty: OpaqueHiddenType<'tcx>,
+        origin: OpaqueTyOrigin,
+    ) -> Ty<'tcx>;
+}
+
+impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
+    /// Given the fully resolved, instantiated type for an opaque
+    /// type, i.e., the value of an inference variable like C1 or C2
+    /// (*), computes the "definition type" for an opaque type
+    /// definition -- that is, the inferred value of `Foo1<'x>` or
+    /// `Foo2<'x>` that we would conceptually use in its definition:
+    /// ```ignore (illustrative)
+    /// type Foo1<'x> = impl Bar<'x> = AAA;  // <-- this type AAA
+    /// type Foo2<'x> = impl Bar<'x> = BBB;  // <-- or this type BBB
+    /// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
+    /// ```
+    /// Note that these values are defined in terms of a distinct set of
+    /// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
+    /// purpose of this function is to do that translation.
+    ///
+    /// (*) C1 and C2 were introduced in the comments on
+    /// `register_member_constraints`. Read that comment for more context.
+    ///
+    /// # Parameters
+    ///
+    /// - `def_id`, the `impl Trait` type
+    /// - `substs`, the substs  used to instantiate this opaque type
+    /// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
+    ///   `opaque_defn.concrete_ty`
+    #[instrument(level = "debug", skip(self))]
+    fn infer_opaque_definition_from_instantiation(
+        &self,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        instantiated_ty: OpaqueHiddenType<'tcx>,
+        origin: OpaqueTyOrigin,
+    ) -> Ty<'tcx> {
+        if self.is_tainted_by_errors() {
+            return self.tcx.ty_error();
+        }
+
+        let OpaqueTypeKey { def_id, substs } = opaque_type_key;
+
+        // Use substs to build up a reverse map from regions to their
+        // identity mappings. This is necessary because of `impl
+        // Trait` lifetimes are computed by replacing existing
+        // lifetimes with 'static and remapping only those used in the
+        // `impl Trait` return type, resulting in the parameters
+        // shifting.
+        let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id);
+        debug!(?id_substs);
+        let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> =
+            substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect();
+        debug!("map = {:#?}", map);
+
+        // Convert the type from the function into a type valid outside
+        // the function, by replacing invalid regions with 'static,
+        // after producing an error for each of them.
+        let definition_ty = instantiated_ty.ty.fold_with(&mut ReverseMapper::new(
+            self.tcx,
+            def_id,
+            map,
+            instantiated_ty.ty,
+            instantiated_ty.span,
+        ));
+        debug!(?definition_ty);
+
+        if !check_opaque_type_parameter_valid(
+            self.tcx,
+            opaque_type_key,
+            origin,
+            instantiated_ty.span,
+        ) {
+            return self.tcx.ty_error();
+        }
+
+        // Only check this for TAIT. RPIT already supports `src/test/ui/impl-trait/nested-return-type2.rs`
+        // on stable and we'd break that.
+        if let OpaqueTyOrigin::TyAlias = origin {
+            // This logic duplicates most of `check_opaque_meets_bounds`.
+            // FIXME(oli-obk): Also do region checks here and then consider removing `check_opaque_meets_bounds` entirely.
+            let param_env = self.tcx.param_env(def_id);
+            let body_id = self.tcx.local_def_id_to_hir_id(def_id.as_local().unwrap());
+            self.tcx.infer_ctxt().enter(move |infcx| {
+                // Require the hidden type to be well-formed with only the generics of the opaque type.
+                // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
+                // hidden type is well formed even without those bounds.
+                let predicate =
+                    ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into()))
+                        .to_predicate(infcx.tcx);
+                let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
+
+                // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
+                // the bounds that the function supplies.
+                match infcx.register_hidden_type(
+                    OpaqueTypeKey { def_id, substs: id_substs },
+                    ObligationCause::misc(instantiated_ty.span, body_id),
+                    param_env,
+                    definition_ty,
+                    origin,
+                ) {
+                    Ok(infer_ok) => {
+                        for obligation in infer_ok.obligations {
+                            fulfillment_cx.register_predicate_obligation(&infcx, obligation);
+                        }
+                    }
+                    Err(err) => {
+                        infcx
+                            .report_mismatched_types(
+                                &ObligationCause::misc(instantiated_ty.span, body_id),
+                                self.tcx.mk_opaque(def_id, id_substs),
+                                definition_ty,
+                                err,
+                            )
+                            .emit();
+                    }
+                }
+
+                fulfillment_cx.register_predicate_obligation(
+                    &infcx,
+                    Obligation::misc(instantiated_ty.span, body_id, param_env, predicate),
+                );
+
+                // Check that all obligations are satisfied by the implementation's
+                // version.
+                let errors = fulfillment_cx.select_all_or_error(&infcx);
+
+                let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
+
+                if errors.is_empty() {
+                    definition_ty
+                } else {
+                    infcx.report_fulfillment_errors(&errors, None, false);
+                    self.tcx.ty_error()
+                }
+            })
+        } else {
+            definition_ty
+        }
+    }
+}
+
+fn check_opaque_type_parameter_valid(
+    tcx: TyCtxt<'_>,
+    opaque_type_key: OpaqueTypeKey<'_>,
+    origin: OpaqueTyOrigin,
+    span: Span,
+) -> bool {
+    match origin {
+        // No need to check return position impl trait (RPIT)
+        // because for type and const parameters they are correct
+        // by construction: we convert
+        //
+        // fn foo<P0..Pn>() -> impl Trait
+        //
+        // into
+        //
+        // type Foo<P0...Pn>
+        // fn foo<P0..Pn>() -> Foo<P0...Pn>.
+        //
+        // For lifetime parameters we convert
+        //
+        // fn foo<'l0..'ln>() -> impl Trait<'l0..'lm>
+        //
+        // into
+        //
+        // type foo::<'p0..'pn>::Foo<'q0..'qm>
+        // fn foo<l0..'ln>() -> foo::<'static..'static>::Foo<'l0..'lm>.
+        //
+        // which would error here on all of the `'static` args.
+        OpaqueTyOrigin::FnReturn(..) | OpaqueTyOrigin::AsyncFn(..) => return true,
+        // Check these
+        OpaqueTyOrigin::TyAlias => {}
+    }
+    let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
+    let mut seen_params: FxHashMap<_, Vec<_>> = FxHashMap::default();
+    for (i, arg) in opaque_type_key.substs.iter().enumerate() {
+        let arg_is_param = match arg.unpack() {
+            GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
+            GenericArgKind::Lifetime(lt) if lt.is_static() => {
+                tcx.sess
+                    .struct_span_err(span, "non-defining opaque type use in defining scope")
+                    .span_label(
+                        tcx.def_span(opaque_generics.param_at(i, tcx).def_id),
+                        "cannot use static lifetime; use a bound lifetime \
+                                    instead or remove the lifetime parameter from the \
+                                    opaque type",
+                    )
+                    .emit();
+                return false;
+            }
+            GenericArgKind::Lifetime(lt) => {
+                matches!(*lt, ty::ReEarlyBound(_) | ty::ReFree(_))
+            }
+            GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
+        };
+
+        if arg_is_param {
+            seen_params.entry(arg).or_default().push(i);
+        } else {
+            // Prevent `fn foo() -> Foo<u32>` from being defining.
+            let opaque_param = opaque_generics.param_at(i, tcx);
+            tcx.sess
+                .struct_span_err(span, "non-defining opaque type use in defining scope")
+                .span_note(
+                    tcx.def_span(opaque_param.def_id),
+                    &format!(
+                        "used non-generic {} `{}` for generic parameter",
+                        opaque_param.kind.descr(),
+                        arg,
+                    ),
+                )
+                .emit();
+            return false;
+        }
+    }
+
+    for (_, indices) in seen_params {
+        if indices.len() > 1 {
+            let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
+            let spans: Vec<_> = indices
+                .into_iter()
+                .map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
+                .collect();
+            tcx.sess
+                .struct_span_err(span, "non-defining opaque type use in defining scope")
+                .span_note(spans, &format!("{} used multiple times", descr))
+                .emit();
+            return false;
+        }
+    }
+    true
+}
+
+struct ReverseMapper<'tcx> {
+    tcx: TyCtxt<'tcx>,
+
+    opaque_type_def_id: DefId,
+    map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
+    map_missing_regions_to_empty: bool,
+
+    /// initially `Some`, set to `None` once error has been reported
+    hidden_ty: Option<Ty<'tcx>>,
+
+    /// Span of function being checked.
+    span: Span,
+}
+
+impl<'tcx> ReverseMapper<'tcx> {
+    fn new(
+        tcx: TyCtxt<'tcx>,
+        opaque_type_def_id: DefId,
+        map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
+        hidden_ty: Ty<'tcx>,
+        span: Span,
+    ) -> Self {
+        Self {
+            tcx,
+            opaque_type_def_id,
+            map,
+            map_missing_regions_to_empty: 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;
+        let kind = kind.fold_with(self);
+        self.map_missing_regions_to_empty = false;
+        kind
+    }
+
+    fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
+        assert!(!self.map_missing_regions_to_empty);
+        kind.fold_with(self)
+    }
+}
+
+impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    #[instrument(skip(self), level = "debug")]
+    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
+        match *r {
+            // Ignore bound regions and `'static` regions that appear in the
+            // type, we only need to remap regions that reference lifetimes
+            // from the function declaration.
+            // This would ignore `'r` in a type like `for<'r> fn(&'r u32)`.
+            ty::ReLateBound(..) | ty::ReStatic => return r,
+
+            // If regions have been erased (by writeback), don't try to unerase
+            // them.
+            ty::ReErased => return r,
+
+            // The regions that we expect from borrow checking.
+            ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReEmpty(ty::UniverseIndex::ROOT) => {}
+
+            ty::ReEmpty(_) | 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.
+                bug!("unexpected region kind in opaque type: {:?}", r);
+            }
+        }
+
+        let generics = self.tcx().generics_of(self.opaque_type_def_id);
+        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 generics.parent.is_some() => {
+                if let Some(hidden_ty) = self.hidden_ty.take() {
+                    unexpected_hidden_region_diagnostic(
+                        self.tcx,
+                        self.tcx.def_span(self.opaque_type_def_id),
+                        hidden_ty,
+                        r,
+                    )
+                    .emit();
+                }
+                self.tcx.lifetimes.re_root_empty
+            }
+            None => {
+                self.tcx
+                    .sess
+                    .struct_span_err(self.span, "non-defining opaque type use in defining scope")
+                    .span_label(
+                        self.span,
+                        format!(
+                            "lifetime `{}` is part of concrete type but not used in \
+                                 parameter list of the `impl Trait` type alias",
+                            r
+                        ),
+                    )
+                    .emit();
+
+                self.tcx().lifetimes.re_static
+            }
+        }
+    }
+
+    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
+        match *ty.kind() {
+            ty::Closure(def_id, substs) => {
+                // I am a horrible monster and I pray for death. When
+                // we encounter a closure here, it is always a closure
+                // from within the function that we are currently
+                // type-checking -- one that is now being encapsulated
+                // in an opaque type. Ideally, we would
+                // go through the types/lifetimes that it references
+                // and treat them just like we would any other type,
+                // which means we would error out if we find any
+                // reference to a type/region that is not in the
+                // "reverse map".
+                //
+                // **However,** in the case of closures, there is a
+                // somewhat subtle (read: hacky) consideration. The
+                // problem is that our closure types currently include
+                // all the lifetime parameters declared on the
+                // enclosing function, even if they are unused by the
+                // closure itself. We can't readily filter them out,
+                // so here we replace those values with `'empty`. This
+                // can't really make a difference to the rest of the
+                // compiler; those regions are ignored for the
+                // outlives relation, and hence don't affect trait
+                // selection or auto traits, and they are erased
+                // during codegen.
+
+                let generics = self.tcx.generics_of(def_id);
+                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)
+                    } else {
+                        // ...but not elsewhere.
+                        self.fold_kind_normally(kind)
+                    }
+                }));
+
+                self.tcx.mk_closure(def_id, substs)
+            }
+
+            ty::Generator(def_id, substs, movability) => {
+                let generics = self.tcx.generics_of(def_id);
+                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)
+                    } else {
+                        // ...but not elsewhere.
+                        self.fold_kind_normally(kind)
+                    }
+                }));
+
+                self.tcx.mk_generator(def_id, substs, movability)
+            }
+
+            ty::Param(param) => {
+                // Look it up in the substitution list.
+                match self.map.get(&ty.into()).map(|k| k.unpack()) {
+                    // Found it in the substitution list; replace with the parameter from the
+                    // opaque type.
+                    Some(GenericArgKind::Type(t1)) => t1,
+                    Some(u) => panic!("type mapped to unexpected kind: {:?}", u),
+                    None => {
+                        debug!(?param, ?self.map);
+                        self.tcx
+                            .sess
+                            .struct_span_err(
+                                self.span,
+                                &format!(
+                                    "type parameter `{}` is part of concrete type but not \
+                                          used in parameter list for the `impl Trait` type alias",
+                                    ty
+                                ),
+                            )
+                            .emit();
+
+                        self.tcx().ty_error()
+                    }
+                }
+            }
+
+            _ => ty.super_fold_with(self),
+        }
+    }
+
+    fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
+        trace!("checking const {:?}", ct);
+        // Find a const parameter
+        match ct.kind() {
+            ty::ConstKind::Param(..) => {
+                // Look it up in the substitution list.
+                match self.map.get(&ct.into()).map(|k| k.unpack()) {
+                    // Found it in the substitution list, replace with the parameter from the
+                    // opaque type.
+                    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().const_error(ct.ty())
+                    }
+                }
+            }
+
+            _ => ct,
+        }
+    }
+}
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 89d84fcf09cfe..2a7713bc4df3b 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -503,7 +503,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
 
         let root_empty = self
             .infcx
-            .next_nll_region_var(NllRegionVariableOrigin::RootEmptyRegion)
+            .next_nll_region_var(NllRegionVariableOrigin::Existential { from_forall: true })
             .to_region_vid();
 
         UniversalRegions {
diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
index ef72e6efb946b..48972321a9f40 100644
--- a/compiler/rustc_codegen_cranelift/src/constant.rs
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -167,6 +167,7 @@ pub(crate) fn codegen_const_value<'tcx>(
     }
 
     match const_val {
+        ConstValue::ZeroSized => unreachable!(), // we already handles ZST above
         ConstValue::Scalar(x) => match x {
             Scalar::Int(int) => {
                 if fx.clif_type(layout.ty).is_some() {
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
index ce341406eaf45..ea3007951d6c5 100644
--- a/compiler/rustc_codegen_gcc/src/common.rs
+++ b/compiler/rustc_codegen_gcc/src/common.rs
@@ -9,7 +9,6 @@ use rustc_codegen_ssa::traits::{
     StaticMethods,
 };
 use rustc_middle::mir::Mutability;
-use rustc_middle::ty::ScalarInt;
 use rustc_middle::ty::layout::{TyAndLayout, LayoutOf};
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
 use rustc_span::Symbol;
@@ -157,13 +156,13 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         None
     }
 
+    fn zst_to_backend(&self, _ty: Type<'gcc>) -> RValue<'gcc> {
+        self.const_undef(self.type_ix(0))
+    }
+
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, ty: Type<'gcc>) -> RValue<'gcc> {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
-            Scalar::Int(ScalarInt::ZST) => {
-                assert_eq!(0, layout.size(self).bytes());
-                self.const_undef(self.type_ix(0))
-            }
             Scalar::Int(int) => {
                 let data = int.assert_bits(layout.size(self));
 
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
index d37aadeb523a1..40356af295db6 100644
--- a/compiler/rustc_codegen_llvm/src/common.rs
+++ b/compiler/rustc_codegen_llvm/src/common.rs
@@ -13,7 +13,6 @@ use rustc_codegen_ssa::traits::*;
 use rustc_middle::bug;
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
-use rustc_middle::ty::ScalarInt;
 use rustc_span::symbol::Symbol;
 use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size};
 
@@ -219,13 +218,13 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         })
     }
 
+    fn zst_to_backend(&self, _llty: &'ll Type) -> &'ll Value {
+        self.const_undef(self.type_ix(0))
+    }
+
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: &'ll Type) -> &'ll Value {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
-            Scalar::Int(ScalarInt::ZST) => {
-                assert_eq!(0, layout.size(self).bytes());
-                self.const_undef(self.type_ix(0))
-            }
             Scalar::Int(int) => {
                 let data = int.assert_bits(layout.size(self));
                 let llval = self.const_uint_big(self.type_ix(bitsize), data);
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index 2e655ae94cc8b..c612634fce2a6 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -84,6 +84,10 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
                 let llval = bx.scalar_to_backend(x, scalar, bx.immediate_backend_type(layout));
                 OperandValue::Immediate(llval)
             }
+            ConstValue::ZeroSized => {
+                let llval = bx.zst_to_backend(bx.immediate_backend_type(layout));
+                OperandValue::Immediate(llval)
+            }
             ConstValue::Slice { data, start, end } => {
                 let Abi::ScalarPair(a_scalar, _) = layout.abi else {
                     bug!("from_const: invalid ScalarPair layout: {:#?}", layout);
diff --git a/compiler/rustc_codegen_ssa/src/traits/consts.rs b/compiler/rustc_codegen_ssa/src/traits/consts.rs
index c3519a24d5325..8ba4b0d89ee9e 100644
--- a/compiler/rustc_codegen_ssa/src/traits/consts.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/consts.rs
@@ -30,6 +30,7 @@ pub trait ConstMethods<'tcx>: BackendTypes {
     fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value;
 
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: Self::Type) -> Self::Value;
+    fn zst_to_backend(&self, llty: Self::Type) -> Self::Value;
     fn from_const_alloc(
         &self,
         layout: TyAndLayout<'tcx>,
diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
index f84dd9521ee57..b18976302b4ff 100644
--- a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
@@ -2,7 +2,7 @@ use super::{CompileTimeEvalContext, CompileTimeInterpreter, ConstEvalErr};
 use crate::interpret::eval_nullary_intrinsic;
 use crate::interpret::{
     intern_const_alloc_recursive, Allocation, ConstAlloc, ConstValue, CtfeValidationMode, GlobalId,
-    Immediate, InternKind, InterpCx, InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking, Scalar,
+    Immediate, InternKind, InterpCx, InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking,
     ScalarMaybeUninit, StackPopCleanup,
 };
 
@@ -157,7 +157,7 @@ pub(super) fn op_to_const<'tcx>(
                     "this MPlaceTy must come from a validated constant, thus we can assume the \
                 alignment is correct",
                 );
-                ConstValue::Scalar(Scalar::ZST)
+                ConstValue::ZeroSized
             }
         }
     };
diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
index f8b390aaf50e1..2288a4e7b6c78 100644
--- a/compiler/rustc_const_eval/src/const_eval/valtrees.rs
+++ b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
@@ -272,7 +272,7 @@ pub fn valtree_to_const_value<'tcx>(
     match ty.kind() {
         ty::FnDef(..) => {
             assert!(valtree.unwrap_branch().is_empty());
-            ConstValue::Scalar(Scalar::ZST)
+            ConstValue::ZeroSized
         }
         ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => match valtree {
             ty::ValTree::Leaf(scalar_int) => ConstValue::Scalar(Scalar::Int(scalar_int)),
@@ -344,11 +344,7 @@ fn valtree_into_mplace<'tcx>(
 
     match ty.kind() {
         ty::FnDef(_, _) => {
-            ecx.write_immediate(
-                Immediate::Scalar(ScalarMaybeUninit::Scalar(Scalar::ZST)),
-                &place.into(),
-            )
-            .unwrap();
+            ecx.write_immediate(Immediate::Uninit, &place.into()).unwrap();
         }
         ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
             let scalar_int = valtree.unwrap_leaf();
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 3892d1920cef7..2e47cf8921073 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -15,7 +15,7 @@ use rustc_middle::ty::layout::{
 use rustc_middle::ty::{
     self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable,
 };
-use rustc_mir_dataflow::storage::always_live_locals;
+use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_session::Limit;
 use rustc_span::{Pos, Span};
@@ -707,7 +707,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let mut locals = IndexVec::from_elem(dummy, &body.local_decls);
 
         // Now mark those locals as live that have no `Storage*` annotations.
-        let always_live = always_live_locals(self.body());
+        let always_live = always_storage_live_locals(self.body());
         for local in locals.indices() {
             if always_live.contains(local) {
                 locals[local].value = LocalValue::Live(Operand::Immediate(Immediate::Uninit));
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index 805dcb3889539..5e9290d7f1fcc 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -293,8 +293,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         let Some(alloc) = self.get_place_alloc(mplace)? else {
             return Ok(Some(ImmTy {
-                // zero-sized type
-                imm: Scalar::ZST.into(),
+                // zero-sized type can be left uninit
+                imm: Immediate::Uninit,
                 layout: mplace.layout,
             }));
         };
@@ -437,8 +437,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // This makes several assumptions about what layouts we will encounter; we match what
         // codegen does as good as we can (see `extract_field` in `rustc_codegen_ssa/src/mir/operand.rs`).
         let field_val: Immediate<_> = match (*base, base.layout.abi) {
-            // the field contains no information
-            _ if field_layout.is_zst() => Scalar::ZST.into(),
+            // the field contains no information, can be left uninit
+            _ if field_layout.is_zst() => Immediate::Uninit,
             // the field covers the entire type
             _ if field_layout.size == base.layout.size => {
                 assert!(match (base.layout.abi, field_layout.abi) {
@@ -549,8 +549,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, OpTy<'tcx, M::PointerTag>> {
         let layout = self.layout_of_local(frame, local, layout)?;
         let op = if layout.is_zst() {
-            // Do not read from ZST, they might not be initialized
-            Operand::Immediate(Scalar::ZST.into())
+            // Bypass `access_local` (helps in ConstProp)
+            Operand::Immediate(Immediate::Uninit)
         } else {
             *M::access_local(frame, local)?
         };
@@ -705,6 +705,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 Operand::Indirect(MemPlace::from_ptr(ptr.into()))
             }
             ConstValue::Scalar(x) => Operand::Immediate(tag_scalar(x)?.into()),
+            ConstValue::ZeroSized => Operand::Immediate(Immediate::Uninit),
             ConstValue::Slice { data, start, end } => {
                 // We rely on mutability being set correctly in `data` to prevent writes
                 // where none should happen.
diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index 56ecc5535285b..2dfe226030aac 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -15,7 +15,7 @@ use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeFoldable, TypeVisitable};
 use rustc_mir_dataflow::impls::MaybeStorageLive;
-use rustc_mir_dataflow::storage::always_live_locals;
+use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::{Analysis, ResultsCursor};
 use rustc_target::abi::{Size, VariantIdx};
 
@@ -49,7 +49,7 @@ impl<'tcx> MirPass<'tcx> for Validator {
         let param_env = tcx.param_env(def_id);
         let mir_phase = self.mir_phase;
 
-        let always_live_locals = always_live_locals(body);
+        let always_live_locals = always_storage_live_locals(body);
         let storage_liveness = MaybeStorageLive::new(always_live_locals)
             .into_engine(tcx, body)
             .iterate_to_fixpoint()
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 6d74e9a9f2b9e..85ea8eb393782 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -63,7 +63,7 @@ impl HumanReadableErrorType {
         bundle: Option<Lrc<FluentBundle>>,
         fallback_bundle: LazyFallbackBundle,
         teach: bool,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> EmitterWriter {
         let (short, color_config) = self.unzip();
@@ -76,7 +76,7 @@ impl HumanReadableErrorType {
             short,
             teach,
             color,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         )
     }
@@ -710,7 +710,7 @@ pub struct EmitterWriter {
     short_message: bool,
     teach: bool,
     ui_testing: bool,
-    terminal_width: Option<usize>,
+    diagnostic_width: Option<usize>,
 
     macro_backtrace: bool,
 }
@@ -730,7 +730,7 @@ impl EmitterWriter {
         fallback_bundle: LazyFallbackBundle,
         short_message: bool,
         teach: bool,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> EmitterWriter {
         let dst = Destination::from_stderr(color_config);
@@ -742,7 +742,7 @@ impl EmitterWriter {
             short_message,
             teach,
             ui_testing: false,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         }
     }
@@ -755,7 +755,7 @@ impl EmitterWriter {
         short_message: bool,
         teach: bool,
         colored: bool,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> EmitterWriter {
         EmitterWriter {
@@ -766,7 +766,7 @@ impl EmitterWriter {
             short_message,
             teach,
             ui_testing: false,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         }
     }
@@ -1615,7 +1615,7 @@ impl EmitterWriter {
                     width_offset + annotated_file.multiline_depth + 1
                 };
 
-                let column_width = if let Some(width) = self.terminal_width {
+                let column_width = if let Some(width) = self.diagnostic_width {
                     width.saturating_sub(code_offset)
                 } else if self.ui_testing {
                     DEFAULT_COLUMN_WIDTH
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index d4d1491c16945..b8cd334b4c6c6 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -42,7 +42,7 @@ pub struct JsonEmitter {
     pretty: bool,
     ui_testing: bool,
     json_rendered: HumanReadableErrorType,
-    terminal_width: Option<usize>,
+    diagnostic_width: Option<usize>,
     macro_backtrace: bool,
 }
 
@@ -54,7 +54,7 @@ impl JsonEmitter {
         fallback_bundle: LazyFallbackBundle,
         pretty: bool,
         json_rendered: HumanReadableErrorType,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> JsonEmitter {
         JsonEmitter {
@@ -66,7 +66,7 @@ impl JsonEmitter {
             pretty,
             ui_testing: false,
             json_rendered,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         }
     }
@@ -76,7 +76,7 @@ impl JsonEmitter {
         json_rendered: HumanReadableErrorType,
         fluent_bundle: Option<Lrc<FluentBundle>>,
         fallback_bundle: LazyFallbackBundle,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> JsonEmitter {
         let file_path_mapping = FilePathMapping::empty();
@@ -87,7 +87,7 @@ impl JsonEmitter {
             fallback_bundle,
             pretty,
             json_rendered,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         )
     }
@@ -100,7 +100,7 @@ impl JsonEmitter {
         fallback_bundle: LazyFallbackBundle,
         pretty: bool,
         json_rendered: HumanReadableErrorType,
-        terminal_width: Option<usize>,
+        diagnostic_width: Option<usize>,
         macro_backtrace: bool,
     ) -> JsonEmitter {
         JsonEmitter {
@@ -112,7 +112,7 @@ impl JsonEmitter {
             pretty,
             ui_testing: false,
             json_rendered,
-            terminal_width,
+            diagnostic_width,
             macro_backtrace,
         }
     }
@@ -345,7 +345,7 @@ impl Diagnostic {
                 je.fluent_bundle.clone(),
                 je.fallback_bundle.clone(),
                 false,
-                je.terminal_width,
+                je.diagnostic_width,
                 je.macro_backtrace,
             )
             .ui_testing(je.ui_testing)
diff --git a/compiler/rustc_infer/src/infer/free_regions.rs b/compiler/rustc_infer/src/infer/free_regions.rs
index fad949a3bc6a1..d566634a49203 100644
--- a/compiler/rustc_infer/src/infer/free_regions.rs
+++ b/compiler/rustc_infer/src/infer/free_regions.rs
@@ -4,7 +4,7 @@
 //! and use that to decide when one free region outlives another, and so forth.
 
 use rustc_data_structures::transitive_relation::TransitiveRelation;
-use rustc_middle::ty::{self, Lift, Region, TyCtxt};
+use rustc_middle::ty::{Lift, Region, TyCtxt};
 
 /// Combines a `FreeRegionMap` and a `TyCtxt`.
 ///
@@ -49,7 +49,7 @@ impl<'tcx> FreeRegionMap<'tcx> {
     // (with the exception that `'static: 'x` is not notable)
     pub fn relate_regions(&mut self, sub: Region<'tcx>, sup: Region<'tcx>) {
         debug!("relate_regions(sub={:?}, sup={:?})", sub, sup);
-        if self.is_free_or_static(sub) && self.is_free(sup) {
+        if sub.is_free_or_static() && sup.is_free() {
             self.relation.add(sub, sup)
         }
     }
@@ -68,7 +68,7 @@ impl<'tcx> FreeRegionMap<'tcx> {
         r_a: Region<'tcx>,
         r_b: Region<'tcx>,
     ) -> bool {
-        assert!(self.is_free_or_static(r_a) && self.is_free_or_static(r_b));
+        assert!(r_a.is_free_or_static() && r_b.is_free_or_static());
         let re_static = tcx.lifetimes.re_static;
         if self.check_relation(re_static, r_b) {
             // `'a <= 'static` is always true, and not stored in the
@@ -85,20 +85,6 @@ impl<'tcx> FreeRegionMap<'tcx> {
         r_a == r_b || self.relation.contains(r_a, r_b)
     }
 
-    /// True for free regions other than `'static`.
-    pub fn is_free(&self, r: Region<'_>) -> bool {
-        matches!(*r, ty::ReEarlyBound(_) | ty::ReFree(_))
-    }
-
-    /// True if `r` is a free region or static of the sort that this
-    /// free region map can be used with.
-    pub fn is_free_or_static(&self, r: Region<'_>) -> bool {
-        match *r {
-            ty::ReStatic => true,
-            _ => self.is_free(r),
-        }
-    }
-
     /// Computes the least-upper-bound of two free regions. In some
     /// cases, this is more conservative than necessary, in order to
     /// avoid making arbitrary choices. See
@@ -110,8 +96,8 @@ impl<'tcx> FreeRegionMap<'tcx> {
         r_b: Region<'tcx>,
     ) -> Region<'tcx> {
         debug!("lub_free_regions(r_a={:?}, r_b={:?})", r_a, r_b);
-        assert!(self.is_free(r_a));
-        assert!(self.is_free(r_b));
+        assert!(r_a.is_free());
+        assert!(r_b.is_free());
         let result = if r_a == r_b {
             r_a
         } else {
diff --git a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
index 87fa22b3835ef..3783cfb4cc5c8 100644
--- a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
+++ b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
@@ -47,7 +47,6 @@ pub(crate) fn resolve<'tcx>(
 #[derive(Clone)]
 pub struct LexicalRegionResolutions<'tcx> {
     pub(crate) values: IndexVec<RegionVid, VarValue<'tcx>>,
-    pub(crate) error_region: ty::Region<'tcx>,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -140,7 +139,6 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
     /// empty region. The `expansion` phase will grow this larger.
     fn construct_var_data(&self, tcx: TyCtxt<'tcx>) -> LexicalRegionResolutions<'tcx> {
         LexicalRegionResolutions {
-            error_region: tcx.lifetimes.re_static,
             values: IndexVec::from_fn_n(
                 |vid| {
                     let vid_universe = self.var_infos[vid].universe;
@@ -310,7 +308,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
 
         // Check for the case where we know that `'b: 'static` -- in that case,
         // `a <= b` for all `a`.
-        let b_free_or_static = self.region_rels.free_regions.is_free_or_static(b);
+        let b_free_or_static = b.is_free_or_static();
         if b_free_or_static && sub_free_regions(tcx.lifetimes.re_static, b) {
             return true;
         }
@@ -320,7 +318,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
         // `lub` relationship defined below, since sometimes the "lub"
         // is actually the `postdom_upper_bound` (see
         // `TransitiveRelation` for more details).
-        let a_free_or_static = self.region_rels.free_regions.is_free_or_static(a);
+        let a_free_or_static = a.is_free_or_static();
         if a_free_or_static && b_free_or_static {
             return sub_free_regions(a, b);
         }
@@ -864,10 +862,7 @@ impl<'tcx> LexicalRegionResolutions<'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        tcx.fold_regions(value, |r, _db| match *r {
-            ty::ReVar(rid) => self.resolve_var(rid),
-            _ => r,
-        })
+        tcx.fold_regions(value, |r, _db| self.resolve_region(tcx, r))
     }
 
     fn value(&self, rid: RegionVid) -> &VarValue<'tcx> {
@@ -878,12 +873,19 @@ impl<'tcx> LexicalRegionResolutions<'tcx> {
         &mut self.values[rid]
     }
 
-    pub fn resolve_var(&self, rid: RegionVid) -> ty::Region<'tcx> {
-        let result = match self.values[rid] {
-            VarValue::Value(r) => r,
-            VarValue::ErrorValue => self.error_region,
+    pub(crate) fn resolve_region(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        r: ty::Region<'tcx>,
+    ) -> ty::Region<'tcx> {
+        let result = match *r {
+            ty::ReVar(rid) => match self.values[rid] {
+                VarValue::Value(r) => r,
+                VarValue::ErrorValue => tcx.lifetimes.re_static,
+            },
+            _ => r,
         };
-        debug!("resolve_var({:?}) = {:?}", rid, result);
+        debug!("resolve_region({:?}) = {:?}", r, result);
         result
     }
 }
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 991fd23ab4344..6e0f2d687437b 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -466,9 +466,6 @@ pub enum NllRegionVariableOrigin {
     /// from a `for<'a> T` binder). Meant to represent "any region".
     Placeholder(ty::PlaceholderRegion),
 
-    /// The variable we create to represent `'empty(U0)`.
-    RootEmptyRegion,
-
     Existential {
         /// If this is true, then this variable was created to represent a lifetime
         /// bound in a `for` binder. For example, it might have been created to
@@ -1250,7 +1247,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         };
 
         let lexical_region_resolutions = LexicalRegionResolutions {
-            error_region: self.tcx.lifetimes.re_static,
             values: rustc_index::vec::IndexVec::from_elem_n(
                 crate::infer::lexical_region_resolve::VarValue::Value(self.tcx.lifetimes.re_erased),
                 var_infos.len(),
diff --git a/compiler/rustc_infer/src/infer/resolve.rs b/compiler/rustc_infer/src/infer/resolve.rs
index a614568742920..3d99f0958f7f9 100644
--- a/compiler/rustc_infer/src/infer/resolve.rs
+++ b/compiler/rustc_infer/src/infer/resolve.rs
@@ -206,13 +206,13 @@ impl<'a, 'tcx> FallibleTypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> {
 
     fn try_fold_region(&mut self, r: ty::Region<'tcx>) -> Result<ty::Region<'tcx>, Self::Error> {
         match *r {
-            ty::ReVar(rid) => Ok(self
+            ty::ReVar(_) => Ok(self
                 .infcx
                 .lexical_region_resolutions
                 .borrow()
                 .as_ref()
                 .expect("region resolution not performed")
-                .resolve_var(rid)),
+                .resolve_region(self.infcx.tcx, r)),
             _ => Ok(r),
         }
     }
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 30a29ed6ed38f..1bb79a0264dd1 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -649,6 +649,7 @@ fn test_debugging_options_tracking_hash() {
     untracked!(dlltool, Some(PathBuf::from("custom_dlltool.exe")));
     untracked!(dont_buffer_diagnostics, true);
     untracked!(dump_dep_graph, true);
+    untracked!(dump_drop_tracking_cfg, Some("cfg.dot".to_string()));
     untracked!(dump_mir, Some(String::from("abc")));
     untracked!(dump_mir_dataflow, true);
     untracked!(dump_mir_dir, String::from("abc"));
@@ -689,7 +690,6 @@ fn test_debugging_options_tracking_hash() {
     untracked!(span_debug, true);
     untracked!(span_free_formats, true);
     untracked!(temps_dir, Some(String::from("abc")));
-    untracked!(terminal_width, Some(80));
     untracked!(threads, 99);
     untracked!(time, true);
     untracked!(time_llvm_passes, true);
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 46c34247d4027..ef06c457bf4bc 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -59,6 +59,7 @@
 #![feature(drain_filter)]
 #![feature(intra_doc_pointers)]
 #![feature(yeet_expr)]
+#![feature(const_option)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]
 
diff --git a/compiler/rustc_middle/src/mir/interpret/value.rs b/compiler/rustc_middle/src/mir/interpret/value.rs
index 8ecbb5ab0b31f..22bbe29c10555 100644
--- a/compiler/rustc_middle/src/mir/interpret/value.rs
+++ b/compiler/rustc_middle/src/mir/interpret/value.rs
@@ -29,11 +29,14 @@ pub struct ConstAlloc<'tcx> {
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
 #[derive(HashStable)]
 pub enum ConstValue<'tcx> {
-    /// Used only for types with `layout::abi::Scalar` ABI and ZSTs.
+    /// Used only for types with `layout::abi::Scalar` ABI.
     ///
     /// Not using the enum `Value` to encode that this must not be `Uninit`.
     Scalar(Scalar),
 
+    /// Only used for ZSTs.
+    ZeroSized,
+
     /// Used only for `&[u8]` and `&str`
     Slice { data: ConstAllocation<'tcx>, start: usize, end: usize },
 
@@ -55,6 +58,7 @@ impl<'a, 'tcx> Lift<'tcx> for ConstValue<'a> {
     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ConstValue<'tcx>> {
         Some(match self {
             ConstValue::Scalar(s) => ConstValue::Scalar(s),
+            ConstValue::ZeroSized => ConstValue::ZeroSized,
             ConstValue::Slice { data, start, end } => {
                 ConstValue::Slice { data: tcx.lift(data)?, start, end }
             }
@@ -69,7 +73,7 @@ impl<'tcx> ConstValue<'tcx> {
     #[inline]
     pub fn try_to_scalar(&self) -> Option<Scalar<AllocId>> {
         match *self {
-            ConstValue::ByRef { .. } | ConstValue::Slice { .. } => None,
+            ConstValue::ByRef { .. } | ConstValue::Slice { .. } | ConstValue::ZeroSized => None,
             ConstValue::Scalar(val) => Some(val),
         }
     }
@@ -111,10 +115,6 @@ impl<'tcx> ConstValue<'tcx> {
     pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self {
         ConstValue::Scalar(Scalar::from_machine_usize(i, cx))
     }
-
-    pub fn zst() -> Self {
-        Self::Scalar(Scalar::ZST)
-    }
 }
 
 /// A `Scalar` represents an immediate, primitive value existing outside of a
@@ -194,8 +194,6 @@ impl<Tag> From<ScalarInt> for Scalar<Tag> {
 }
 
 impl<Tag> Scalar<Tag> {
-    pub const ZST: Self = Scalar::Int(ScalarInt::ZST);
-
     #[inline(always)]
     pub fn from_pointer(ptr: Pointer<Tag>, cx: &impl HasDataLayout) -> Self {
         Scalar::Ptr(ptr, u8::try_from(cx.pointer_size().bytes()).unwrap())
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 9368612810198..fc8b3112b871f 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -1048,6 +1048,8 @@ impl BasicBlock {
 ///////////////////////////////////////////////////////////////////////////
 // BasicBlockData
 
+/// Data for a basic block, including a list of its statements.
+///
 /// See [`BasicBlock`] for documentation on what basic blocks are at a high level.
 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
 pub struct BasicBlockData<'tcx> {
@@ -1079,7 +1081,7 @@ impl<'tcx> BasicBlockData<'tcx> {
     /// Accessor for terminator.
     ///
     /// Terminator may not be None after construction of the basic block is complete. This accessor
-    /// provides a convenience way to reach the terminator.
+    /// provides a convenient way to reach the terminator.
     #[inline]
     pub fn terminator(&self) -> &Terminator<'tcx> {
         self.terminator.as_ref().expect("invalid terminator state")
@@ -1286,6 +1288,7 @@ impl<O: fmt::Debug> fmt::Debug for AssertKind<O> {
 ///////////////////////////////////////////////////////////////////////////
 // Statements
 
+/// A statement in a basic block, including information about its source code.
 #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
 pub struct Statement<'tcx> {
     pub source_info: SourceInfo,
@@ -1708,7 +1711,7 @@ impl<'tcx> Operand<'tcx> {
         Operand::Constant(Box::new(Constant {
             span,
             user_ty: None,
-            literal: ConstantKind::Val(ConstValue::zst(), ty),
+            literal: ConstantKind::Val(ConstValue::ZeroSized, ty),
         }))
     }
 
@@ -2193,7 +2196,7 @@ impl<'tcx> ConstantKind<'tcx> {
 
     #[inline]
     pub fn zero_sized(ty: Ty<'tcx>) -> Self {
-        let cv = ConstValue::Scalar(Scalar::ZST);
+        let cv = ConstValue::ZeroSized;
         Self::Val(cv, ty)
     }
 
@@ -2769,6 +2772,13 @@ fn pretty_print_const_value<'tcx>(
                 fmt.write_str(&cx.into_buffer())?;
                 return Ok(());
             }
+            (ConstValue::ZeroSized, ty::FnDef(d, s)) => {
+                let mut cx = FmtPrinter::new(tcx, Namespace::ValueNS);
+                cx.print_alloc_ids = true;
+                let cx = cx.print_value_path(*d, s)?;
+                fmt.write_str(&cx.into_buffer())?;
+                return Ok(());
+            }
             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
             // their fields instead of just dumping the memory.
             _ => {}
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 24c6cd91d0a54..e2fa37ee7be80 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -448,7 +448,9 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                 self.push(&format!("+ user_ty: {:?}", user_ty));
             }
 
+            // FIXME: this is a poor version of `pretty_print_const_value`.
             let fmt_val = |val: &ConstValue<'tcx>| match val {
+                ConstValue::ZeroSized => format!("<ZST>"),
                 ConstValue::Scalar(s) => format!("Scalar({:?})", s),
                 ConstValue::Slice { .. } => format!("Slice(..)"),
                 ConstValue::ByRef { .. } => format!("ByRef(..)"),
@@ -679,6 +681,7 @@ pub fn write_allocations<'tcx>(
             ConstValue::Scalar(interpret::Scalar::Int { .. }) => {
                 Either::Left(Either::Right(std::iter::empty()))
             }
+            ConstValue::ZeroSized => Either::Left(Either::Right(std::iter::empty())),
             ConstValue::ByRef { alloc, .. } | ConstValue::Slice { data: alloc, .. } => {
                 Either::Right(alloc_ids_from_alloc(alloc))
             }
diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs
index 03c11c2863fbb..3fe6394ad7e9c 100644
--- a/compiler/rustc_middle/src/thir.rs
+++ b/compiler/rustc_middle/src/thir.rs
@@ -419,6 +419,10 @@ pub enum ExprKind<'tcx> {
         lit: ty::ScalarInt,
         user_ty: Option<Canonical<'tcx, UserType<'tcx>>>,
     },
+    /// A literal of a ZST type.
+    ZstLiteral {
+        user_ty: Option<Canonical<'tcx, UserType<'tcx>>>,
+    },
     /// Associated constants and named constants
     NamedConst {
         def_id: DefId,
@@ -454,12 +458,6 @@ pub enum ExprKind<'tcx> {
     },
 }
 
-impl<'tcx> ExprKind<'tcx> {
-    pub fn zero_sized_literal(user_ty: Option<Canonical<'tcx, UserType<'tcx>>>) -> Self {
-        ExprKind::NonHirLiteral { lit: ty::ScalarInt::ZST, user_ty }
-    }
-}
-
 /// Represents the association of a field identifier and an expression.
 ///
 /// This is used in struct constructors.
diff --git a/compiler/rustc_middle/src/thir/visit.rs b/compiler/rustc_middle/src/thir/visit.rs
index 8c8ebb0a6b87a..c8d09875c2896 100644
--- a/compiler/rustc_middle/src/thir/visit.rs
+++ b/compiler/rustc_middle/src/thir/visit.rs
@@ -129,6 +129,7 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
         Closure { closure_id: _, substs: _, upvars: _, movability: _, fake_reads: _ } => {}
         Literal { lit: _, neg: _ } => {}
         NonHirLiteral { lit: _, user_ty: _ } => {}
+        ZstLiteral { user_ty: _ } => {}
         NamedConst { def_id: _, substs: _, user_ty: _ } => {}
         ConstParam { param: _, def_id: _ } => {}
         StaticRef { alloc_id: _, ty: _, def_id: _ } => {}
diff --git a/compiler/rustc_middle/src/ty/consts/int.rs b/compiler/rustc_middle/src/ty/consts/int.rs
index c7c2692281ebb..7436f0f6f4d33 100644
--- a/compiler/rustc_middle/src/ty/consts/int.rs
+++ b/compiler/rustc_middle/src/ty/consts/int.rs
@@ -4,6 +4,7 @@ use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use rustc_target::abi::Size;
 use std::convert::{TryFrom, TryInto};
 use std::fmt;
+use std::num::NonZeroU8;
 
 use crate::ty::TyCtxt;
 
@@ -123,7 +124,7 @@ pub struct ScalarInt {
     /// The first `size` bytes of `data` are the value.
     /// Do not try to read less or more bytes than that. The remaining bytes must be 0.
     data: u128,
-    size: u8,
+    size: NonZeroU8,
 }
 
 // Cannot derive these, as the derives take references to the fields, and we
@@ -135,33 +136,31 @@ impl<CTX> crate::ty::HashStable<CTX> for ScalarInt {
         // Since `Self` is a packed struct, that would create a possibly unaligned reference,
         // which is UB.
         { self.data }.hash_stable(hcx, hasher);
-        self.size.hash_stable(hcx, hasher);
+        self.size.get().hash_stable(hcx, hasher);
     }
 }
 
 impl<S: Encoder> Encodable<S> for ScalarInt {
     fn encode(&self, s: &mut S) {
         s.emit_u128(self.data);
-        s.emit_u8(self.size);
+        s.emit_u8(self.size.get());
     }
 }
 
 impl<D: Decoder> Decodable<D> for ScalarInt {
     fn decode(d: &mut D) -> ScalarInt {
-        ScalarInt { data: d.read_u128(), size: d.read_u8() }
+        ScalarInt { data: d.read_u128(), size: NonZeroU8::new(d.read_u8()).unwrap() }
     }
 }
 
 impl ScalarInt {
-    pub const TRUE: ScalarInt = ScalarInt { data: 1_u128, size: 1 };
+    pub const TRUE: ScalarInt = ScalarInt { data: 1_u128, size: NonZeroU8::new(1).unwrap() };
 
-    pub const FALSE: ScalarInt = ScalarInt { data: 0_u128, size: 1 };
-
-    pub const ZST: ScalarInt = ScalarInt { data: 0_u128, size: 0 };
+    pub const FALSE: ScalarInt = ScalarInt { data: 0_u128, size: NonZeroU8::new(1).unwrap() };
 
     #[inline]
     pub fn size(self) -> Size {
-        Size::from_bytes(self.size)
+        Size::from_bytes(self.size.get())
     }
 
     /// Make sure the `data` fits in `size`.
@@ -185,7 +184,7 @@ impl ScalarInt {
 
     #[inline]
     pub fn null(size: Size) -> Self {
-        Self { data: 0, size: size.bytes() as u8 }
+        Self { data: 0, size: NonZeroU8::new(size.bytes() as u8).unwrap() }
     }
 
     #[inline]
@@ -197,7 +196,7 @@ impl ScalarInt {
     pub fn try_from_uint(i: impl Into<u128>, size: Size) -> Option<Self> {
         let data = i.into();
         if size.truncate(data) == data {
-            Some(Self { data, size: size.bytes() as u8 })
+            Some(Self { data, size: NonZeroU8::new(size.bytes() as u8).unwrap() })
         } else {
             None
         }
@@ -209,7 +208,7 @@ impl ScalarInt {
         // `into` performed sign extension, we have to truncate
         let truncated = size.truncate(i as u128);
         if size.sign_extend(truncated) as i128 == i {
-            Some(Self { data: truncated, size: size.bytes() as u8 })
+            Some(Self { data: truncated, size: NonZeroU8::new(size.bytes() as u8).unwrap() })
         } else {
             None
         }
@@ -225,7 +224,7 @@ impl ScalarInt {
     #[inline]
     pub fn to_bits(self, target_size: Size) -> Result<u128, Size> {
         assert_ne!(target_size.bytes(), 0, "you should never look at the bits of a ZST");
-        if target_size.bytes() == u64::from(self.size) {
+        if target_size.bytes() == u64::from(self.size.get()) {
             self.check_data();
             Ok(self.data)
         } else {
@@ -339,7 +338,7 @@ macro_rules! from {
                 fn from(u: $ty) -> Self {
                     Self {
                         data: u128::from(u),
-                        size: std::mem::size_of::<$ty>() as u8,
+                        size: NonZeroU8::new(std::mem::size_of::<$ty>() as u8).unwrap(),
                     }
                 }
             }
@@ -382,7 +381,7 @@ impl TryFrom<ScalarInt> for bool {
 impl From<char> for ScalarInt {
     #[inline]
     fn from(c: char) -> Self {
-        Self { data: c as u128, size: std::mem::size_of::<char>() as u8 }
+        Self { data: c as u128, size: NonZeroU8::new(std::mem::size_of::<char>() as u8).unwrap() }
     }
 }
 
@@ -409,7 +408,7 @@ impl From<Single> for ScalarInt {
     #[inline]
     fn from(f: Single) -> Self {
         // We trust apfloat to give us properly truncated data.
-        Self { data: f.to_bits(), size: 4 }
+        Self { data: f.to_bits(), size: NonZeroU8::new((Single::BITS / 8) as u8).unwrap() }
     }
 }
 
@@ -425,7 +424,7 @@ impl From<Double> for ScalarInt {
     #[inline]
     fn from(f: Double) -> Self {
         // We trust apfloat to give us properly truncated data.
-        Self { data: f.to_bits(), size: 8 }
+        Self { data: f.to_bits(), size: NonZeroU8::new((Double::BITS / 8) as u8).unwrap() }
     }
 }
 
@@ -439,13 +438,8 @@ impl TryFrom<ScalarInt> for Double {
 
 impl fmt::Debug for ScalarInt {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.size == 0 {
-            self.check_data();
-            write!(f, "<ZST>")
-        } else {
-            // Dispatch to LowerHex below.
-            write!(f, "0x{:x}", self)
-        }
+        // Dispatch to LowerHex below.
+        write!(f, "0x{:x}", self)
     }
 }
 
@@ -463,7 +457,7 @@ impl fmt::LowerHex for ScalarInt {
         // would thus borrow `self.data`. Since `Self`
         // is a packed struct, that would create a possibly unaligned reference, which
         // is UB.
-        write!(f, "{:01$x}", { self.data }, self.size as usize * 2)
+        write!(f, "{:01$x}", { self.data }, self.size.get() as usize * 2)
     }
 }
 
@@ -477,7 +471,7 @@ impl fmt::UpperHex for ScalarInt {
         // would thus borrow `self.data`. Since `Self`
         // is a packed struct, that would create a possibly unaligned reference, which
         // is UB.
-        write!(f, "{:01$X}", { self.data }, self.size as usize * 2)
+        write!(f, "{:01$X}", { self.data }, self.size.get() as usize * 2)
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 887236c484bcb..f721a175c9834 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1355,10 +1355,6 @@ pub trait PrettyPrinter<'tcx>:
                     " as ",
                 )?;
             }
-            // For function type zsts just printing the path is enough
-            ty::FnDef(d, s) if int == ScalarInt::ZST => {
-                p!(print_value_path(*d, s))
-            }
             // Nontrivial types with scalar bit representation
             _ => {
                 let print = |mut this: Self| {
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 815e39aab5715..03e4319bbf1a8 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1570,6 +1570,19 @@ impl<'tcx> Region<'tcx> {
             _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
         }
     }
+
+    /// True for free regions other than `'static`.
+    pub fn is_free(self) -> bool {
+        matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
+    }
+
+    /// True if `self` is a free region or static.
+    pub fn is_free_or_static(self) -> bool {
+        match *self {
+            ty::ReStatic => true,
+            _ => self.is_free(),
+        }
+    }
 }
 
 /// Type utilities
diff --git a/compiler/rustc_mir_build/src/build/expr/as_constant.rs b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
index 3d6e50f0c0622..648d10b9e42a8 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_constant.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
@@ -49,11 +49,22 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         inferred_ty: ty,
                     })
                 });
-
                 let literal = ConstantKind::Val(ConstValue::Scalar(Scalar::Int(lit)), ty);
 
                 Constant { span, user_ty: user_ty, literal }
             }
+            ExprKind::ZstLiteral { user_ty } => {
+                let user_ty = user_ty.map(|user_ty| {
+                    this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
+                        span,
+                        user_ty,
+                        inferred_ty: ty,
+                    })
+                });
+                let literal = ConstantKind::Val(ConstValue::ZeroSized, ty);
+
+                Constant { span, user_ty: user_ty, literal }
+            }
             ExprKind::NamedConst { def_id, substs, user_ty } => {
                 let user_ty = user_ty.map(|user_ty| {
                     this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation {
diff --git a/compiler/rustc_mir_build/src/build/expr/as_place.rs b/compiler/rustc_mir_build/src/build/expr/as_place.rs
index e77f5931dd65d..e88f9dc1f08f5 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_place.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_place.rs
@@ -603,6 +603,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             | ExprKind::Literal { .. }
             | ExprKind::NamedConst { .. }
             | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ZstLiteral { .. }
             | ExprKind::ConstParam { .. }
             | ExprKind::ConstBlock { .. }
             | ExprKind::StaticRef { .. }
diff --git a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
index e3a383f86a76a..15f2d17c4e08b 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
@@ -415,6 +415,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             ExprKind::Literal { .. }
             | ExprKind::NamedConst { .. }
             | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ZstLiteral { .. }
             | ExprKind::ConstParam { .. }
             | ExprKind::ConstBlock { .. }
             | ExprKind::StaticRef { .. } => {
diff --git a/compiler/rustc_mir_build/src/build/expr/category.rs b/compiler/rustc_mir_build/src/build/expr/category.rs
index b1a706439342e..a4386319dc1aa 100644
--- a/compiler/rustc_mir_build/src/build/expr/category.rs
+++ b/compiler/rustc_mir_build/src/build/expr/category.rs
@@ -72,6 +72,7 @@ impl Category {
             ExprKind::ConstBlock { .. }
             | ExprKind::Literal { .. }
             | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ZstLiteral { .. }
             | ExprKind::ConstParam { .. }
             | ExprKind::StaticRef { .. }
             | ExprKind::NamedConst { .. } => Some(Category::Constant),
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index cffb67ef01328..017d43d10a9a9 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -559,6 +559,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             | ExprKind::Literal { .. }
             | ExprKind::NamedConst { .. }
             | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ZstLiteral { .. }
             | ExprKind::ConstParam { .. }
             | ExprKind::ThreadLocalRef(_)
             | ExprKind::StaticRef { .. } => {
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 94b2722dca86d..8585199faaf5a 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -307,6 +307,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
             | ExprKind::Literal { .. }
             | ExprKind::NamedConst { .. }
             | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ZstLiteral { .. }
             | ExprKind::ConstParam { .. }
             | ExprKind::ConstBlock { .. }
             | ExprKind::Deref { .. }
diff --git a/compiler/rustc_mir_build/src/thir/cx/expr.rs b/compiler/rustc_mir_build/src/thir/cx/expr.rs
index 4bc3d216a40d6..4eb3607e9cca0 100644
--- a/compiler/rustc_mir_build/src/thir/cx/expr.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/expr.rs
@@ -799,7 +799,7 @@ impl<'tcx> Cx<'tcx> {
             }
         };
         let ty = self.tcx().mk_fn_def(def_id, substs);
-        Expr { temp_lifetime, ty, span, kind: ExprKind::zero_sized_literal(user_ty) }
+        Expr { temp_lifetime, ty, span, kind: ExprKind::ZstLiteral { user_ty } }
     }
 
     fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> ArmId {
@@ -828,7 +828,7 @@ impl<'tcx> Cx<'tcx> {
             | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
             | Res::SelfCtor(_) => {
                 let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
-                ExprKind::zero_sized_literal(user_ty)
+                ExprKind::ZstLiteral { user_ty }
             }
 
             Res::Def(DefKind::ConstParam, def_id) => {
diff --git a/compiler/rustc_mir_dataflow/src/storage.rs b/compiler/rustc_mir_dataflow/src/storage.rs
index 4a354c4c65b08..566c9d2d5054e 100644
--- a/compiler/rustc_mir_dataflow/src/storage.rs
+++ b/compiler/rustc_mir_dataflow/src/storage.rs
@@ -7,7 +7,7 @@ use rustc_middle::mir::{self, Local};
 //
 // FIXME: Currently, we need to traverse the entire MIR to compute this. We should instead store it
 // as a field in the `LocalDecl` for each `Local`.
-pub fn always_live_locals(body: &mir::Body<'_>) -> BitSet<Local> {
+pub fn always_storage_live_locals(body: &mir::Body<'_>) -> BitSet<Local> {
     let mut always_live_locals = BitSet::new_filled(body.local_decls.len());
 
     for block in body.basic_blocks() {
diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs
index 9078b8a1cb7cd..9fdea8359671f 100644
--- a/compiler/rustc_mir_transform/src/generator.rs
+++ b/compiler/rustc_mir_transform/src/generator.rs
@@ -67,7 +67,7 @@ use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
 use rustc_mir_dataflow::impls::{
     MaybeBorrowedLocals, MaybeLiveLocals, MaybeRequiresStorage, MaybeStorageLive,
 };
-use rustc_mir_dataflow::storage;
+use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::{self, Analysis};
 use rustc_target::abi::VariantIdx;
 use rustc_target::spec::PanicStrategy;
@@ -1379,7 +1379,7 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
             },
         );
 
-        let always_live_locals = storage::always_live_locals(&body);
+        let always_live_locals = always_storage_live_locals(&body);
 
         let liveness_info =
             locals_live_across_suspend_points(tcx, body, &always_live_locals, movable);
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 2c43563b10474..f9387e29262ae 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1393,7 +1393,9 @@ impl<'a> Parser<'a> {
             self.parse_yield_expr(attrs)
         } else if self.is_do_yeet() {
             self.parse_yeet_expr(attrs)
-        } else if self.eat_keyword(kw::Let) {
+        } else if self.check_keyword(kw::Let) {
+            self.manage_let_chains_context();
+            self.bump();
             self.parse_let_expr(attrs)
         } else if self.eat_keyword(kw::Underscore) {
             Ok(self.mk_expr(self.prev_token.span, ExprKind::Underscore, attrs))
@@ -2355,16 +2357,30 @@ impl<'a> Parser<'a> {
         Ok(cond)
     }
 
+    // Checks if `let` is in an invalid position like `let x = let y = 1;` or
+    // if the current `let` is in a let_chains context but nested in another
+    // expression like `if let Some(_) = _opt && [1, 2, 3][let _ = ()] = 1`.
+    //
+    // This method expects that the current token is `let`.
+    fn manage_let_chains_context(&mut self) {
+        debug_assert!(matches!(self.token.kind, TokenKind::Ident(kw::Let, _)));
+        let is_in_a_let_chains_context_but_nested_in_other_expr = self.let_expr_allowed
+            && !matches!(
+                self.prev_token.kind,
+                TokenKind::AndAnd
+                    | TokenKind::CloseDelim(Delimiter::Brace)
+                    | TokenKind::Ident(kw::If, _)
+                    | TokenKind::Ident(kw::While, _)
+            );
+        if !self.let_expr_allowed || is_in_a_let_chains_context_but_nested_in_other_expr {
+            self.struct_span_err(self.token.span, "expected expression, found `let` statement")
+                .emit();
+        }
+    }
+
     /// Parses a `let $pat = $expr` pseudo-expression.
     /// The `let` token has already been eaten.
     fn parse_let_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> {
-        if !self.let_expr_allowed {
-            self.struct_span_err(
-                self.prev_token.span,
-                "expected expression, found `let` statement",
-            )
-            .emit();
-        }
         let lo = self.prev_token.span;
         let pat = self.parse_pat_allow_top_alt(
             None,
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index e7717f1367cb0..b7da0f229420b 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -726,6 +726,7 @@ impl Default for Options {
             prints: Vec::new(),
             cg: Default::default(),
             error_format: ErrorOutputType::default(),
+            diagnostic_width: None,
             externs: Externs(BTreeMap::new()),
             crate_name: None,
             libs: Vec::new(),
@@ -1427,6 +1428,12 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
                                  never  = never colorize output",
             "auto|always|never",
         ),
+        opt::opt_s(
+            "",
+            "diagnostic-width",
+            "Inform rustc of the width of the output so that diagnostics can be truncated to fit",
+            "WIDTH",
+        ),
         opt::multi_s(
             "",
             "remap-path-prefix",
@@ -2202,6 +2209,10 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let error_format = parse_error_format(matches, color, json_rendered);
 
+    let diagnostic_width = matches.opt_get("diagnostic-width").unwrap_or_else(|_| {
+        early_error(error_format, "`--diagnostic-width` must be an positive integer");
+    });
+
     let unparsed_crate_types = matches.opt_strs("crate-type");
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
         .unwrap_or_else(|e| early_error(error_format, &e));
@@ -2474,6 +2485,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         prints,
         cg,
         error_format,
+        diagnostic_width,
         externs,
         unstable_features: UnstableFeatures::from_environment(crate_name.as_deref()),
         crate_name,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index be70ea5d5e480..b617eb02eb6e3 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -170,6 +170,7 @@ top_level_options!(
 
         test: bool [TRACKED],
         error_format: ErrorOutputType [UNTRACKED],
+        diagnostic_width: Option<usize> [UNTRACKED],
 
         /// If `Some`, enable incremental compilation, using the given
         /// directory to store intermediate results.
@@ -1245,6 +1246,8 @@ options! {
     dump_dep_graph: bool = (false, parse_bool, [UNTRACKED],
         "dump the dependency graph to $RUST_DEP_GRAPH (default: /tmp/dep_graph.gv) \
         (default: no)"),
+    dump_drop_tracking_cfg: Option<String> = (None, parse_opt_string, [UNTRACKED],
+        "dump drop-tracking control-flow graph as a `.dot` file (default: no)"),
     dump_mir: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "dump MIR state to file.
         `val` is used to select which passes and functions to dump. For example:
@@ -1388,6 +1391,8 @@ options! {
         "panic strategy for out-of-memory handling"),
     osx_rpath_install_name: bool = (false, parse_bool, [TRACKED],
         "pass `-install_name @rpath/...` to the macOS linker (default: no)"),
+    diagnostic_width: Option<usize> = (None, parse_opt_number, [UNTRACKED],
+        "set the current output width for diagnostic truncation"),
     panic_abort_tests: bool = (false, parse_bool, [TRACKED],
         "support compiling tests with panic=abort (default: no)"),
     panic_in_drop: PanicStrategy = (PanicStrategy::Unwind, parse_panic_strategy, [TRACKED],
@@ -1514,8 +1519,6 @@ options! {
         "show extended diagnostic help (default: no)"),
     temps_dir: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "the directory the intermediate files are written to"),
-    terminal_width: Option<usize> = (None, parse_opt_number, [UNTRACKED],
-        "set the current terminal width"),
     // Diagnostics are considered side-effects of a query (see `QuerySideEffects`) and are saved
     // alongside query results and changes to translation options can affect diagnostics - so
     // translation options should be tracked.
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 2a5ddd4e9e420..52b9ee9471802 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1162,7 +1162,7 @@ fn default_emitter(
                         fallback_bundle,
                         short,
                         sopts.debugging_opts.teach,
-                        sopts.debugging_opts.terminal_width,
+                        sopts.diagnostic_width,
                         macro_backtrace,
                     ),
                     Some(dst) => EmitterWriter::new(
@@ -1173,7 +1173,7 @@ fn default_emitter(
                         short,
                         false, // no teach messages when writing to a buffer
                         false, // no colors when writing to a buffer
-                        None,  // no terminal width
+                        None,  // no diagnostic width
                         macro_backtrace,
                     ),
                 };
@@ -1188,7 +1188,7 @@ fn default_emitter(
                 fallback_bundle,
                 pretty,
                 json_rendered,
-                sopts.debugging_opts.terminal_width,
+                sopts.diagnostic_width,
                 macro_backtrace,
             )
             .ui_testing(sopts.debugging_opts.ui_testing),
@@ -1202,7 +1202,7 @@ fn default_emitter(
                 fallback_bundle,
                 pretty,
                 json_rendered,
-                sopts.debugging_opts.terminal_width,
+                sopts.diagnostic_width,
                 macro_backtrace,
             )
             .ui_testing(sopts.debugging_opts.ui_testing),
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index 44ff3fd73061e..282ee632ce581 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -37,5 +37,4 @@ extern crate smallvec;
 
 pub mod autoderef;
 pub mod infer;
-pub mod opaque_types;
 pub mod traits;
diff --git a/compiler/rustc_trait_selection/src/opaque_types.rs b/compiler/rustc_trait_selection/src/opaque_types.rs
deleted file mode 100644
index d290f7b074cb5..0000000000000
--- a/compiler/rustc_trait_selection/src/opaque_types.rs
+++ /dev/null
@@ -1,545 +0,0 @@
-use crate::traits;
-use crate::traits::error_reporting::InferCtxtExt as _;
-use crate::traits::TraitEngineExt as _;
-use rustc_data_structures::fx::FxHashMap;
-use rustc_hir::def_id::DefId;
-use rustc_hir::OpaqueTyOrigin;
-use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
-use rustc_infer::infer::{InferCtxt, TyCtxtInferExt as _};
-use rustc_infer::traits::{Obligation, ObligationCause, TraitEngine};
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
-use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts};
-use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, ToPredicate, Ty, TyCtxt};
-use rustc_span::Span;
-
-pub trait InferCtxtExt<'tcx> {
-    fn infer_opaque_definition_from_instantiation(
-        &self,
-        opaque_type_key: OpaqueTypeKey<'tcx>,
-        instantiated_ty: OpaqueHiddenType<'tcx>,
-        origin: OpaqueTyOrigin,
-    ) -> Ty<'tcx>;
-}
-
-impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
-    /// Given the fully resolved, instantiated type for an opaque
-    /// type, i.e., the value of an inference variable like C1 or C2
-    /// (*), computes the "definition type" for an opaque type
-    /// definition -- that is, the inferred value of `Foo1<'x>` or
-    /// `Foo2<'x>` that we would conceptually use in its definition:
-    /// ```ignore (illustrative)
-    /// type Foo1<'x> = impl Bar<'x> = AAA;  // <-- this type AAA
-    /// type Foo2<'x> = impl Bar<'x> = BBB;  // <-- or this type BBB
-    /// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
-    /// ```
-    /// Note that these values are defined in terms of a distinct set of
-    /// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
-    /// purpose of this function is to do that translation.
-    ///
-    /// (*) C1 and C2 were introduced in the comments on
-    /// `register_member_constraints`. Read that comment for more context.
-    ///
-    /// # Parameters
-    ///
-    /// - `def_id`, the `impl Trait` type
-    /// - `substs`, the substs  used to instantiate this opaque type
-    /// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
-    ///   `opaque_defn.concrete_ty`
-    #[instrument(level = "debug", skip(self))]
-    fn infer_opaque_definition_from_instantiation(
-        &self,
-        opaque_type_key: OpaqueTypeKey<'tcx>,
-        instantiated_ty: OpaqueHiddenType<'tcx>,
-        origin: OpaqueTyOrigin,
-    ) -> Ty<'tcx> {
-        if self.is_tainted_by_errors() {
-            return self.tcx.ty_error();
-        }
-
-        let OpaqueTypeKey { def_id, substs } = opaque_type_key;
-
-        // Use substs to build up a reverse map from regions to their
-        // identity mappings. This is necessary because of `impl
-        // Trait` lifetimes are computed by replacing existing
-        // lifetimes with 'static and remapping only those used in the
-        // `impl Trait` return type, resulting in the parameters
-        // shifting.
-        let id_substs = InternalSubsts::identity_for_item(self.tcx, def_id);
-        debug!(?id_substs);
-        let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> =
-            substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect();
-        debug!("map = {:#?}", map);
-
-        // Convert the type from the function into a type valid outside
-        // the function, by replacing invalid regions with 'static,
-        // after producing an error for each of them.
-        let definition_ty = instantiated_ty.ty.fold_with(&mut ReverseMapper::new(
-            self.tcx,
-            def_id,
-            map,
-            instantiated_ty.ty,
-            instantiated_ty.span,
-        ));
-        debug!(?definition_ty);
-
-        if !check_opaque_type_parameter_valid(
-            self.tcx,
-            opaque_type_key,
-            origin,
-            instantiated_ty.span,
-        ) {
-            return self.tcx.ty_error();
-        }
-
-        // Only check this for TAIT. RPIT already supports `src/test/ui/impl-trait/nested-return-type2.rs`
-        // on stable and we'd break that.
-        if let OpaqueTyOrigin::TyAlias = origin {
-            // This logic duplicates most of `check_opaque_meets_bounds`.
-            // FIXME(oli-obk): Also do region checks here and then consider removing `check_opaque_meets_bounds` entirely.
-            let param_env = self.tcx.param_env(def_id);
-            let body_id = self.tcx.local_def_id_to_hir_id(def_id.as_local().unwrap());
-            self.tcx.infer_ctxt().enter(move |infcx| {
-                // Require the hidden type to be well-formed with only the generics of the opaque type.
-                // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
-                // hidden type is well formed even without those bounds.
-                let predicate =
-                    ty::Binder::dummy(ty::PredicateKind::WellFormed(definition_ty.into()))
-                        .to_predicate(infcx.tcx);
-                let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
-
-                // Require that the hidden type actually fulfills all the bounds of the opaque type, even without
-                // the bounds that the function supplies.
-                match infcx.register_hidden_type(
-                    OpaqueTypeKey { def_id, substs: id_substs },
-                    ObligationCause::misc(instantiated_ty.span, body_id),
-                    param_env,
-                    definition_ty,
-                    origin,
-                ) {
-                    Ok(infer_ok) => {
-                        for obligation in infer_ok.obligations {
-                            fulfillment_cx.register_predicate_obligation(&infcx, obligation);
-                        }
-                    }
-                    Err(err) => {
-                        infcx
-                            .report_mismatched_types(
-                                &ObligationCause::misc(instantiated_ty.span, body_id),
-                                self.tcx.mk_opaque(def_id, id_substs),
-                                definition_ty,
-                                err,
-                            )
-                            .emit();
-                    }
-                }
-
-                fulfillment_cx.register_predicate_obligation(
-                    &infcx,
-                    Obligation::misc(instantiated_ty.span, body_id, param_env, predicate),
-                );
-
-                // Check that all obligations are satisfied by the implementation's
-                // version.
-                let errors = fulfillment_cx.select_all_or_error(&infcx);
-
-                let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
-
-                if errors.is_empty() {
-                    definition_ty
-                } else {
-                    infcx.report_fulfillment_errors(&errors, None, false);
-                    self.tcx.ty_error()
-                }
-            })
-        } else {
-            definition_ty
-        }
-    }
-}
-
-fn check_opaque_type_parameter_valid(
-    tcx: TyCtxt<'_>,
-    opaque_type_key: OpaqueTypeKey<'_>,
-    origin: OpaqueTyOrigin,
-    span: Span,
-) -> bool {
-    match origin {
-        // No need to check return position impl trait (RPIT)
-        // because for type and const parameters they are correct
-        // by construction: we convert
-        //
-        // fn foo<P0..Pn>() -> impl Trait
-        //
-        // into
-        //
-        // type Foo<P0...Pn>
-        // fn foo<P0..Pn>() -> Foo<P0...Pn>.
-        //
-        // For lifetime parameters we convert
-        //
-        // fn foo<'l0..'ln>() -> impl Trait<'l0..'lm>
-        //
-        // into
-        //
-        // type foo::<'p0..'pn>::Foo<'q0..'qm>
-        // fn foo<l0..'ln>() -> foo::<'static..'static>::Foo<'l0..'lm>.
-        //
-        // which would error here on all of the `'static` args.
-        OpaqueTyOrigin::FnReturn(..) | OpaqueTyOrigin::AsyncFn(..) => return true,
-        // Check these
-        OpaqueTyOrigin::TyAlias => {}
-    }
-    let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
-    let mut seen_params: FxHashMap<_, Vec<_>> = FxHashMap::default();
-    for (i, arg) in opaque_type_key.substs.iter().enumerate() {
-        let arg_is_param = match arg.unpack() {
-            GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
-            GenericArgKind::Lifetime(lt) if lt.is_static() => {
-                tcx.sess
-                    .struct_span_err(span, "non-defining opaque type use in defining scope")
-                    .span_label(
-                        tcx.def_span(opaque_generics.param_at(i, tcx).def_id),
-                        "cannot use static lifetime; use a bound lifetime \
-                                    instead or remove the lifetime parameter from the \
-                                    opaque type",
-                    )
-                    .emit();
-                return false;
-            }
-            GenericArgKind::Lifetime(lt) => {
-                matches!(*lt, ty::ReEarlyBound(_) | ty::ReFree(_))
-            }
-            GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
-        };
-
-        if arg_is_param {
-            seen_params.entry(arg).or_default().push(i);
-        } else {
-            // Prevent `fn foo() -> Foo<u32>` from being defining.
-            let opaque_param = opaque_generics.param_at(i, tcx);
-            tcx.sess
-                .struct_span_err(span, "non-defining opaque type use in defining scope")
-                .span_note(
-                    tcx.def_span(opaque_param.def_id),
-                    &format!(
-                        "used non-generic {} `{}` for generic parameter",
-                        opaque_param.kind.descr(),
-                        arg,
-                    ),
-                )
-                .emit();
-            return false;
-        }
-    }
-
-    for (_, indices) in seen_params {
-        if indices.len() > 1 {
-            let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
-            let spans: Vec<_> = indices
-                .into_iter()
-                .map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
-                .collect();
-            tcx.sess
-                .struct_span_err(span, "non-defining opaque type use in defining scope")
-                .span_note(spans, &format!("{} used multiple times", descr))
-                .emit();
-            return false;
-        }
-    }
-    true
-}
-
-struct ReverseMapper<'tcx> {
-    tcx: TyCtxt<'tcx>,
-
-    opaque_type_def_id: DefId,
-    map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
-    map_missing_regions_to_empty: bool,
-
-    /// initially `Some`, set to `None` once error has been reported
-    hidden_ty: Option<Ty<'tcx>>,
-
-    /// Span of function being checked.
-    span: Span,
-}
-
-impl<'tcx> ReverseMapper<'tcx> {
-    fn new(
-        tcx: TyCtxt<'tcx>,
-        opaque_type_def_id: DefId,
-        map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
-        hidden_ty: Ty<'tcx>,
-        span: Span,
-    ) -> Self {
-        Self {
-            tcx,
-            opaque_type_def_id,
-            map,
-            map_missing_regions_to_empty: 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;
-        let kind = kind.fold_with(self);
-        self.map_missing_regions_to_empty = false;
-        kind
-    }
-
-    fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
-        assert!(!self.map_missing_regions_to_empty);
-        kind.fold_with(self)
-    }
-}
-
-impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> {
-    fn tcx(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    #[instrument(skip(self), level = "debug")]
-    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        match *r {
-            // Ignore bound regions and `'static` regions that appear in the
-            // type, we only need to remap regions that reference lifetimes
-            // from the function declaration.
-            // This would ignore `'r` in a type like `for<'r> fn(&'r u32)`.
-            ty::ReLateBound(..) | ty::ReStatic => return r,
-
-            // If regions have been erased (by writeback), don't try to unerase
-            // them.
-            ty::ReErased => return r,
-
-            // The regions that we expect from borrow checking.
-            ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReEmpty(ty::UniverseIndex::ROOT) => {}
-
-            ty::ReEmpty(_) | 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.
-                bug!("unexpected region kind in opaque type: {:?}", r);
-            }
-        }
-
-        let generics = self.tcx().generics_of(self.opaque_type_def_id);
-        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 generics.parent.is_some() => {
-                if let Some(hidden_ty) = self.hidden_ty.take() {
-                    unexpected_hidden_region_diagnostic(
-                        self.tcx,
-                        self.tcx.def_span(self.opaque_type_def_id),
-                        hidden_ty,
-                        r,
-                    )
-                    .emit();
-                }
-                self.tcx.lifetimes.re_root_empty
-            }
-            None => {
-                self.tcx
-                    .sess
-                    .struct_span_err(self.span, "non-defining opaque type use in defining scope")
-                    .span_label(
-                        self.span,
-                        format!(
-                            "lifetime `{}` is part of concrete type but not used in \
-                                 parameter list of the `impl Trait` type alias",
-                            r
-                        ),
-                    )
-                    .emit();
-
-                self.tcx().lifetimes.re_static
-            }
-        }
-    }
-
-    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        match *ty.kind() {
-            ty::Closure(def_id, substs) => {
-                // I am a horrible monster and I pray for death. When
-                // we encounter a closure here, it is always a closure
-                // from within the function that we are currently
-                // type-checking -- one that is now being encapsulated
-                // in an opaque type. Ideally, we would
-                // go through the types/lifetimes that it references
-                // and treat them just like we would any other type,
-                // which means we would error out if we find any
-                // reference to a type/region that is not in the
-                // "reverse map".
-                //
-                // **However,** in the case of closures, there is a
-                // somewhat subtle (read: hacky) consideration. The
-                // problem is that our closure types currently include
-                // all the lifetime parameters declared on the
-                // enclosing function, even if they are unused by the
-                // closure itself. We can't readily filter them out,
-                // so here we replace those values with `'empty`. This
-                // can't really make a difference to the rest of the
-                // compiler; those regions are ignored for the
-                // outlives relation, and hence don't affect trait
-                // selection or auto traits, and they are erased
-                // during codegen.
-
-                let generics = self.tcx.generics_of(def_id);
-                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)
-                    } else {
-                        // ...but not elsewhere.
-                        self.fold_kind_normally(kind)
-                    }
-                }));
-
-                self.tcx.mk_closure(def_id, substs)
-            }
-
-            ty::Generator(def_id, substs, movability) => {
-                let generics = self.tcx.generics_of(def_id);
-                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)
-                    } else {
-                        // ...but not elsewhere.
-                        self.fold_kind_normally(kind)
-                    }
-                }));
-
-                self.tcx.mk_generator(def_id, substs, movability)
-            }
-
-            ty::Param(param) => {
-                // Look it up in the substitution list.
-                match self.map.get(&ty.into()).map(|k| k.unpack()) {
-                    // Found it in the substitution list; replace with the parameter from the
-                    // opaque type.
-                    Some(GenericArgKind::Type(t1)) => t1,
-                    Some(u) => panic!("type mapped to unexpected kind: {:?}", u),
-                    None => {
-                        debug!(?param, ?self.map);
-                        self.tcx
-                            .sess
-                            .struct_span_err(
-                                self.span,
-                                &format!(
-                                    "type parameter `{}` is part of concrete type but not \
-                                          used in parameter list for the `impl Trait` type alias",
-                                    ty
-                                ),
-                            )
-                            .emit();
-
-                        self.tcx().ty_error()
-                    }
-                }
-            }
-
-            _ => ty.super_fold_with(self),
-        }
-    }
-
-    fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
-        trace!("checking const {:?}", ct);
-        // Find a const parameter
-        match ct.kind() {
-            ty::ConstKind::Param(..) => {
-                // Look it up in the substitution list.
-                match self.map.get(&ct.into()).map(|k| k.unpack()) {
-                    // Found it in the substitution list, replace with the parameter from the
-                    // opaque type.
-                    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().const_error(ct.ty())
-                    }
-                }
-            }
-
-            _ => ct,
-        }
-    }
-}
-
-/// Given a set of predicates that apply to an object type, returns
-/// the region bounds that the (erased) `Self` type must
-/// outlive. Precisely *because* the `Self` type is erased, the
-/// parameter `erased_self_ty` must be supplied to indicate what type
-/// has been used to represent `Self` in the predicates
-/// themselves. This should really be a unique type; `FreshTy(0)` is a
-/// popular choice.
-///
-/// N.B., in some cases, particularly around higher-ranked bounds,
-/// this function returns a kind of conservative approximation.
-/// That is, all regions returned by this function are definitely
-/// required, but there may be other region bounds that are not
-/// returned, as well as requirements like `for<'a> T: 'a`.
-///
-/// Requires that trait definitions have been processed so that we can
-/// elaborate predicates and walk supertraits.
-#[instrument(skip(tcx, predicates), level = "debug")]
-pub(crate) fn required_region_bounds<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    erased_self_ty: Ty<'tcx>,
-    predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
-) -> Vec<ty::Region<'tcx>> {
-    assert!(!erased_self_ty.has_escaping_bound_vars());
-
-    traits::elaborate_predicates(tcx, predicates)
-        .filter_map(|obligation| {
-            debug!(?obligation);
-            match obligation.predicate.kind().skip_binder() {
-                ty::PredicateKind::Projection(..)
-                | ty::PredicateKind::Trait(..)
-                | ty::PredicateKind::Subtype(..)
-                | ty::PredicateKind::Coerce(..)
-                | ty::PredicateKind::WellFormed(..)
-                | ty::PredicateKind::ObjectSafe(..)
-                | ty::PredicateKind::ClosureKind(..)
-                | ty::PredicateKind::RegionOutlives(..)
-                | ty::PredicateKind::ConstEvaluatable(..)
-                | ty::PredicateKind::ConstEquate(..)
-                | ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
-                ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ref t, ref r)) => {
-                    // Search for a bound of the form `erased_self_ty
-                    // : 'a`, but be wary of something like `for<'a>
-                    // erased_self_ty : 'a` (we interpret a
-                    // higher-ranked bound like that as 'static,
-                    // though at present the code in `fulfill.rs`
-                    // considers such bounds to be unsatisfiable, so
-                    // it's kind of a moot point since you could never
-                    // construct such an object, but this seems
-                    // correct even if that code changes).
-                    if t == &erased_self_ty && !r.has_escaping_bound_vars() {
-                        Some(*r)
-                    } else {
-                        None
-                    }
-                }
-            }
-        })
-        .collect()
-}
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index f9b4a1583cc74..3a152eff485db 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -451,6 +451,10 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
                 let val = ty::ValTree::from_scalar_int(lit);
                 self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, val, node.ty)))
             }
+            &ExprKind::ZstLiteral { user_ty: _ } => {
+                let val = ty::ValTree::zst();
+                self.nodes.push(Node::Leaf(ty::Const::from_value(self.tcx, val, node.ty)))
+            }
             &ExprKind::NamedConst { def_id, substs, user_ty: _ } => {
                 let uneval = ty::Unevaluated::new(ty::WithOptConstParam::unknown(def_id), substs);
 
diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index d43b3c9091fc6..3dfc7a9cacd97 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -1,5 +1,4 @@
 use crate::infer::InferCtxt;
-use crate::opaque_types::required_region_bounds;
 use crate::traits;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
@@ -810,3 +809,63 @@ pub fn object_region_bounds<'tcx>(
 
     required_region_bounds(tcx, open_ty, predicates)
 }
+
+/// Given a set of predicates that apply to an object type, returns
+/// the region bounds that the (erased) `Self` type must
+/// outlive. Precisely *because* the `Self` type is erased, the
+/// parameter `erased_self_ty` must be supplied to indicate what type
+/// has been used to represent `Self` in the predicates
+/// themselves. This should really be a unique type; `FreshTy(0)` is a
+/// popular choice.
+///
+/// N.B., in some cases, particularly around higher-ranked bounds,
+/// this function returns a kind of conservative approximation.
+/// That is, all regions returned by this function are definitely
+/// required, but there may be other region bounds that are not
+/// returned, as well as requirements like `for<'a> T: 'a`.
+///
+/// Requires that trait definitions have been processed so that we can
+/// elaborate predicates and walk supertraits.
+#[instrument(skip(tcx, predicates), level = "debug")]
+pub(crate) fn required_region_bounds<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    erased_self_ty: Ty<'tcx>,
+    predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
+) -> Vec<ty::Region<'tcx>> {
+    assert!(!erased_self_ty.has_escaping_bound_vars());
+
+    traits::elaborate_predicates(tcx, predicates)
+        .filter_map(|obligation| {
+            debug!(?obligation);
+            match obligation.predicate.kind().skip_binder() {
+                ty::PredicateKind::Projection(..)
+                | ty::PredicateKind::Trait(..)
+                | ty::PredicateKind::Subtype(..)
+                | ty::PredicateKind::Coerce(..)
+                | ty::PredicateKind::WellFormed(..)
+                | ty::PredicateKind::ObjectSafe(..)
+                | ty::PredicateKind::ClosureKind(..)
+                | ty::PredicateKind::RegionOutlives(..)
+                | ty::PredicateKind::ConstEvaluatable(..)
+                | ty::PredicateKind::ConstEquate(..)
+                | ty::PredicateKind::TypeWellFormedFromEnv(..) => None,
+                ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ref t, ref r)) => {
+                    // Search for a bound of the form `erased_self_ty
+                    // : 'a`, but be wary of something like `for<'a>
+                    // erased_self_ty : 'a` (we interpret a
+                    // higher-ranked bound like that as 'static,
+                    // though at present the code in `fulfill.rs`
+                    // considers such bounds to be unsatisfiable, so
+                    // it's kind of a moot point since you could never
+                    // construct such an object, but this seems
+                    // correct even if that code changes).
+                    if t == &erased_self_ty && !r.has_escaping_bound_vars() {
+                        Some(*r)
+                    } else {
+                        None
+                    }
+                }
+            }
+        })
+        .collect()
+}
diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs
index c2b4c478ba387..887c791af76c2 100644
--- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs
@@ -109,7 +109,7 @@ rustc_index::newtype_index! {
 }
 
 /// Identifies a value whose drop state we need to track.
-#[derive(PartialEq, Eq, Hash, Debug, Clone, Copy)]
+#[derive(PartialEq, Eq, Hash, Clone, Copy)]
 enum TrackedValue {
     /// Represents a named variable, such as a let binding, parameter, or upvar.
     ///
@@ -121,6 +121,21 @@ enum TrackedValue {
     Temporary(HirId),
 }
 
+impl Debug for TrackedValue {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        ty::tls::with_opt(|opt_tcx| {
+            if let Some(tcx) = opt_tcx {
+                write!(f, "{}", tcx.hir().node_to_string(self.hir_id()))
+            } else {
+                match self {
+                    Self::Variable(hir_id) => write!(f, "Variable({:?})", hir_id),
+                    Self::Temporary(hir_id) => write!(f, "Temporary({:?})", hir_id),
+                }
+            }
+        })
+    }
+}
+
 impl TrackedValue {
     fn hir_id(&self) -> HirId {
         match self {
@@ -148,7 +163,7 @@ enum TrackedValueConversionError {
     /// Place projects are not currently supported.
     ///
     /// The reasoning around these is kind of subtle, so we choose to be more
-    /// conservative around these for now. There is not reason in theory we
+    /// conservative around these for now. There is no reason in theory we
     /// cannot support these, we just have not implemented it yet.
     PlaceProjectionsNotSupported,
 }
diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs
index 365ff429243f1..111d534abf83b 100644
--- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs
@@ -33,6 +33,9 @@ pub(super) fn build_control_flow_graph<'tcx>(
     intravisit::walk_body(&mut drop_range_visitor, body);
 
     drop_range_visitor.drop_ranges.process_deferred_edges();
+    if let Some(filename) = &tcx.sess.opts.debugging_opts.dump_drop_tracking_cfg {
+        super::cfg_visualize::write_graph_to_file(&drop_range_visitor.drop_ranges, filename, tcx);
+    }
 
     (drop_range_visitor.drop_ranges, drop_range_visitor.places.borrowed_temporaries)
 }
@@ -126,13 +129,14 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> {
     /// ExprUseVisitor's consume callback doesn't go deep enough for our purposes in all
     /// expressions. This method consumes a little deeper into the expression when needed.
     fn consume_expr(&mut self, expr: &hir::Expr<'_>) {
-        debug!("consuming expr {:?}, count={:?}", expr.hir_id, self.expr_index);
+        debug!("consuming expr {:?}, count={:?}", expr.kind, self.expr_index);
         let places = self
             .places
             .consumed
             .get(&expr.hir_id)
             .map_or(vec![], |places| places.iter().cloned().collect());
         for place in places {
+            trace!(?place, "consuming place");
             for_each_consumable(self.hir, place, |value| self.record_drop(value));
         }
     }
diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs
index 20aad7aedf775..c0a0bfe8e1c00 100644
--- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_visualize.rs
@@ -2,6 +2,7 @@
 //! flow graph when needed for debugging.
 
 use rustc_graphviz as dot;
+use rustc_middle::ty::TyCtxt;
 
 use super::{DropRangesBuilder, PostOrderId};
 
@@ -9,22 +10,35 @@ use super::{DropRangesBuilder, PostOrderId};
 ///
 /// It is not normally called, but is kept around to easily add debugging
 /// code when needed.
-#[allow(dead_code)]
-pub(super) fn write_graph_to_file(drop_ranges: &DropRangesBuilder, filename: &str) {
-    dot::render(drop_ranges, &mut std::fs::File::create(filename).unwrap()).unwrap();
+pub(super) fn write_graph_to_file(
+    drop_ranges: &DropRangesBuilder,
+    filename: &str,
+    tcx: TyCtxt<'_>,
+) {
+    dot::render(
+        &DropRangesGraph { drop_ranges, tcx },
+        &mut std::fs::File::create(filename).unwrap(),
+    )
+    .unwrap();
 }
 
-impl<'a> dot::GraphWalk<'a> for DropRangesBuilder {
+struct DropRangesGraph<'a, 'tcx> {
+    drop_ranges: &'a DropRangesBuilder,
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'a> dot::GraphWalk<'a> for DropRangesGraph<'_, '_> {
     type Node = PostOrderId;
 
     type Edge = (PostOrderId, PostOrderId);
 
     fn nodes(&'a self) -> dot::Nodes<'a, Self::Node> {
-        self.nodes.iter_enumerated().map(|(i, _)| i).collect()
+        self.drop_ranges.nodes.iter_enumerated().map(|(i, _)| i).collect()
     }
 
     fn edges(&'a self) -> dot::Edges<'a, Self::Edge> {
-        self.nodes
+        self.drop_ranges
+            .nodes
             .iter_enumerated()
             .flat_map(|(i, node)| {
                 if node.successors.len() == 0 {
@@ -45,7 +59,7 @@ impl<'a> dot::GraphWalk<'a> for DropRangesBuilder {
     }
 }
 
-impl<'a> dot::Labeller<'a> for DropRangesBuilder {
+impl<'a> dot::Labeller<'a> for DropRangesGraph<'_, '_> {
     type Node = PostOrderId;
 
     type Edge = (PostOrderId, PostOrderId);
@@ -61,15 +75,15 @@ impl<'a> dot::Labeller<'a> for DropRangesBuilder {
     fn node_label(&'a self, n: &Self::Node) -> dot::LabelText<'a> {
         dot::LabelText::LabelStr(
             format!(
-                "{:?}, local_id: {}",
-                n,
-                self.post_order_map
+                "{n:?}: {}",
+                self.drop_ranges
+                    .post_order_map
                     .iter()
                     .find(|(_hir_id, &post_order_id)| post_order_id == *n)
-                    .map_or("<unknown>".into(), |(hir_id, _)| format!(
-                        "{}",
-                        hir_id.local_id.index()
-                    ))
+                    .map_or("<unknown>".into(), |(hir_id, _)| self
+                        .tcx
+                        .hir()
+                        .node_to_string(*hir_id))
             )
             .into(),
         )
diff --git a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs
index b22b791f629d7..67cc46f21f00b 100644
--- a/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs
@@ -75,6 +75,7 @@ impl<'tcx> ExprUseDelegate<'tcx> {
         if !self.places.consumed.contains_key(&consumer) {
             self.places.consumed.insert(consumer, <_>::default());
         }
+        debug!(?consumer, ?target, "mark_consumed");
         self.places.consumed.get_mut(&consumer).map(|places| places.insert(target));
     }
 
@@ -136,13 +137,16 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
         place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
         diag_expr_id: HirId,
     ) {
-        let parent = match self.tcx.hir().find_parent_node(place_with_id.hir_id) {
+        let hir = self.tcx.hir();
+        let parent = match hir.find_parent_node(place_with_id.hir_id) {
             Some(parent) => parent,
             None => place_with_id.hir_id,
         };
         debug!(
-            "consume {:?}; diag_expr_id={:?}, using parent {:?}",
-            place_with_id, diag_expr_id, parent
+            "consume {:?}; diag_expr_id={}, using parent {}",
+            place_with_id,
+            hir.node_to_string(diag_expr_id),
+            hir.node_to_string(parent)
         );
         place_with_id
             .try_into()
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 2e89abe202cf6..fa6a5ee1668f8 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -949,6 +949,7 @@ impl<'a> Builder<'a> {
     }
 
     pub(crate) fn download_component(&self, url: &str, dest_path: &Path, help_on_error: &str) {
+        self.verbose(&format!("download {url}"));
         // Use a temporary file in case we crash while downloading, to avoid a corrupt download in cache/.
         let tempfile = self.tempdir().join(dest_path.file_name().unwrap());
         // While bootstrap itself only supports http and https downloads, downstream forks might
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index e71fbff14dd12..ee3b072fe35f2 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -1558,7 +1558,7 @@ fn download_ci_rustc(builder: &Builder<'_>, commit: &str) {
         builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustc"));
         builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustdoc"));
         let lib_dir = bin_root.join("lib");
-        for lib in t!(fs::read_dir(lib_dir)) {
+        for lib in t!(fs::read_dir(&lib_dir), lib_dir.display().to_string()) {
             let lib = t!(lib);
             if lib.path().extension() == Some(OsStr::new("so")) {
                 builder.fix_bin_or_dylib(&lib.path());
@@ -1634,6 +1634,7 @@ fn download_component(
         }
         Some(sha256)
     } else if tarball.exists() {
+        builder.unpack(&tarball, &bin_root, prefix);
         return;
     } else {
         None
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 7ec6eb0be6527..272188f82994c 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -73,6 +73,8 @@ pub(crate) struct Options {
     pub(crate) proc_macro_crate: bool,
     /// How to format errors and warnings.
     pub(crate) error_format: ErrorOutputType,
+    /// Width of output buffer to truncate errors appropriately.
+    pub(crate) diagnostic_width: Option<usize>,
     /// Library search paths to hand to the compiler.
     pub(crate) libs: Vec<SearchPath>,
     /// Library search paths strings to hand to the compiler.
@@ -331,11 +333,12 @@ impl Options {
         let config::JsonConfig { json_rendered, json_unused_externs, .. } =
             config::parse_json(matches);
         let error_format = config::parse_error_format(matches, color, json_rendered);
+        let diagnostic_width = matches.opt_get("diagnostic-width").unwrap_or_default();
 
         let codegen_options = CodegenOptions::build(matches, error_format);
         let debugging_opts = DebuggingOptions::build(matches, error_format);
 
-        let diag = new_handler(error_format, None, &debugging_opts);
+        let diag = new_handler(error_format, None, diagnostic_width, &debugging_opts);
 
         // check for deprecated options
         check_deprecated_options(matches, &diag);
@@ -699,6 +702,7 @@ impl Options {
             input,
             proc_macro_crate,
             error_format,
+            diagnostic_width,
             libs,
             lib_strs,
             externs,
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 51b245e36ba3b..8c494ee28cc1f 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -154,6 +154,7 @@ impl<'tcx> DocContext<'tcx> {
 pub(crate) fn new_handler(
     error_format: ErrorOutputType,
     source_map: Option<Lrc<source_map::SourceMap>>,
+    diagnostic_width: Option<usize>,
     debugging_opts: &DebuggingOptions,
 ) -> rustc_errors::Handler {
     let fallback_bundle =
@@ -169,7 +170,7 @@ pub(crate) fn new_handler(
                     fallback_bundle,
                     short,
                     debugging_opts.teach,
-                    debugging_opts.terminal_width,
+                    diagnostic_width,
                     false,
                 )
                 .ui_testing(debugging_opts.ui_testing),
@@ -187,7 +188,7 @@ pub(crate) fn new_handler(
                     fallback_bundle,
                     pretty,
                     json_rendered,
-                    debugging_opts.terminal_width,
+                    diagnostic_width,
                     false,
                 )
                 .ui_testing(debugging_opts.ui_testing),
@@ -208,6 +209,7 @@ pub(crate) fn create_config(
         crate_name,
         proc_macro_crate,
         error_format,
+        diagnostic_width,
         libs,
         externs,
         mut cfgs,
@@ -266,6 +268,7 @@ pub(crate) fn create_config(
         actually_rustdoc: true,
         debugging_opts,
         error_format,
+        diagnostic_width,
         edition,
         describe_lints,
         crate_name,
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index ded3d9951bd35..0d3ec7ecb6448 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -462,6 +462,14 @@ fn opts() -> Vec<RustcOptGroup> {
                 "human|json|short",
             )
         }),
+        unstable("diagnostic-width", |o| {
+            o.optopt(
+                "",
+                "diagnostic-width",
+                "Provide width of the output for truncated error messages",
+                "WIDTH",
+            )
+        }),
         stable("json", |o| {
             o.optopt("", "json", "Configure the structure of JSON diagnostics", "CONFIG")
         }),
@@ -733,7 +741,12 @@ fn run_renderer<'tcx, T: formats::FormatRenderer<'tcx>>(
 }
 
 fn main_options(options: config::Options) -> MainResult {
-    let diag = core::new_handler(options.error_format, None, &options.debugging_opts);
+    let diag = core::new_handler(
+        options.error_format,
+        None,
+        options.diagnostic_width,
+        &options.debugging_opts,
+    );
 
     match (options.should_test, options.markdown_input()) {
         (true, true) => return wrap_return(&diag, markdown::test(options)),
diff --git a/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.32bit.mir b/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.32bit.mir
index deb5dbad7de67..c8848caa02709 100644
--- a/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.32bit.mir
+++ b/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.32bit.mir
@@ -39,7 +39,7 @@ fn main() -> () {
         _5 = foo(move _6) -> bb1;        // scope 4 at $DIR/array-index-is-temporary.rs:16:21: 16:27
                                          // mir::Constant
                                          // + span: $DIR/array-index-is-temporary.rs:16:21: 16:24
-                                         // + literal: Const { ty: unsafe fn(*mut usize) -> u32 {foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(*mut usize) -> u32 {foo}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.64bit.mir b/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.64bit.mir
index deb5dbad7de67..c8848caa02709 100644
--- a/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.64bit.mir
+++ b/src/test/mir-opt/array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.64bit.mir
@@ -39,7 +39,7 @@ fn main() -> () {
         _5 = foo(move _6) -> bb1;        // scope 4 at $DIR/array-index-is-temporary.rs:16:21: 16:27
                                          // mir::Constant
                                          // + span: $DIR/array-index-is-temporary.rs:16:21: 16:24
-                                         // + literal: Const { ty: unsafe fn(*mut usize) -> u32 {foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(*mut usize) -> u32 {foo}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/box_expr.main.ElaborateDrops.before.mir b/src/test/mir-opt/box_expr.main.ElaborateDrops.before.mir
index 5b1ffc76fe5b3..9b35beccbcc5a 100644
--- a/src/test/mir-opt/box_expr.main.ElaborateDrops.before.mir
+++ b/src/test/mir-opt/box_expr.main.ElaborateDrops.before.mir
@@ -22,7 +22,7 @@ fn main() -> () {
         _4 = alloc::alloc::exchange_malloc(move _2, move _3) -> bb1; // scope 2 at $DIR/box_expr.rs:7:13: 7:25
                                          // mir::Constant
                                          // + span: $DIR/box_expr.rs:7:13: 7:25
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -31,7 +31,7 @@ fn main() -> () {
         (*_5) = S::new() -> [return: bb2, unwind: bb8]; // scope 0 at $DIR/box_expr.rs:7:17: 7:25
                                          // mir::Constant
                                          // + span: $DIR/box_expr.rs:7:17: 7:23
-                                         // + literal: Const { ty: fn() -> S {S::new}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> S {S::new}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -47,7 +47,7 @@ fn main() -> () {
         _6 = std::mem::drop::<Box<S>>(move _7) -> [return: bb4, unwind: bb6]; // scope 1 at $DIR/box_expr.rs:8:5: 8:12
                                          // mir::Constant
                                          // + span: $DIR/box_expr.rs:8:5: 8:9
-                                         // + literal: Const { ty: fn(Box<S>) {std::mem::drop::<Box<S>>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Box<S>) {std::mem::drop::<Box<S>>}, val: Value(<ZST>) }
     }
 
     bb4: {
diff --git a/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff b/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff
index b1ff480324f6b..7ecd67d7c679a 100644
--- a/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff
+++ b/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff
@@ -24,7 +24,7 @@
           _2 = <T as Clone>::clone(move _3) -> bb1; // scope 0 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
                                            // mir::Constant
                                            // + span: $DIR/combine_clone_of_primitives.rs:8:5: 8:9
-                                           // + literal: Const { ty: for<'r> fn(&'r T) -> T {<T as Clone>::clone}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r T) -> T {<T as Clone>::clone}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -37,7 +37,7 @@
 -         _5 = <u64 as Clone>::clone(move _6) -> [return: bb2, unwind: bb4]; // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 -                                          // mir::Constant
 -                                          // + span: $DIR/combine_clone_of_primitives.rs:9:5: 9:11
--                                          // + literal: Const { ty: for<'r> fn(&'r u64) -> u64 {<u64 as Clone>::clone}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r u64) -> u64 {<u64 as Clone>::clone}, val: Value(<ZST>) }
 +         _6 = _7;                         // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 +         _5 = (*_6);                      // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 +         goto -> bb2;                     // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
@@ -53,7 +53,7 @@
 -         _8 = <[f32; 3] as Clone>::clone(move _9) -> [return: bb3, unwind: bb4]; // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 -                                          // mir::Constant
 -                                          // + span: $DIR/combine_clone_of_primitives.rs:10:5: 10:16
--                                          // + literal: Const { ty: for<'r> fn(&'r [f32; 3]) -> [f32; 3] {<[f32; 3] as Clone>::clone}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r [f32; 3]) -> [f32; 3] {<[f32; 3] as Clone>::clone}, val: Value(<ZST>) }
 +         _9 = _10;                        // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 +         _8 = (*_9);                      // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 +         goto -> bb3;                     // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
diff --git a/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
index 268d8f464646f..bc82222d11856 100644
--- a/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
+++ b/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
@@ -33,7 +33,7 @@
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
                                            // mir::Constant
                                            // + span: $DIR/const-promotion-extern-static.rs:9:36: 9:42
-                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
index 322a1b206f948..39dcf2f10c6f2 100644
--- a/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
+++ b/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
@@ -35,7 +35,7 @@
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
                                            // mir::Constant
                                            // + span: $DIR/const-promotion-extern-static.rs:13:47: 13:53
-                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/boxes.main.ConstProp.diff b/src/test/mir-opt/const_prop/boxes.main.ConstProp.diff
index 87302424914d9..919b909435197 100644
--- a/src/test/mir-opt/const_prop/boxes.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/boxes.main.ConstProp.diff
@@ -32,7 +32,7 @@
 +         _6 = alloc::alloc::exchange_malloc(const 4_usize, const 4_usize) -> bb1; // scope 2 at $DIR/boxes.rs:12:14: 12:22
                                            // mir::Constant
                                            // + span: $DIR/boxes.rs:12:14: 12:22
-                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/const_prop_fails_gracefully.main.ConstProp.diff b/src/test/mir-opt/const_prop/const_prop_fails_gracefully.main.ConstProp.diff
index 84d72202d527e..852a2419f558d 100644
--- a/src/test/mir-opt/const_prop/const_prop_fails_gracefully.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/const_prop_fails_gracefully.main.ConstProp.diff
@@ -30,7 +30,7 @@
           _4 = read(move _5) -> bb1;       // scope 1 at $DIR/const_prop_fails_gracefully.rs:8:5: 8:12
                                            // mir::Constant
                                            // + span: $DIR/const_prop_fails_gracefully.rs:8:5: 8:9
-                                           // + literal: Const { ty: fn(usize) {read}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(usize) {read}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/control_flow_simplification.hello.ConstProp.diff b/src/test/mir-opt/const_prop/control_flow_simplification.hello.ConstProp.diff
index d7636c817099a..d0287cc2b2b64 100644
--- a/src/test/mir-opt/const_prop/control_flow_simplification.hello.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/control_flow_simplification.hello.ConstProp.diff
@@ -19,7 +19,7 @@
           _2 = begin_panic::<&str>(const "explicit panic"); // scope 0 at $SRC_DIR/std/src/panic.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-                                           // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/std/src/panic.rs:LL:COL
                                            // + literal: Const { ty: &str, val: Value(Slice(..)) }
diff --git a/src/test/mir-opt/const_prop/issue_66971.main.ConstProp.diff b/src/test/mir-opt/const_prop/issue_66971.main.ConstProp.diff
index e874adebbe01b..5991d7637f50f 100644
--- a/src/test/mir-opt/const_prop/issue_66971.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/issue_66971.main.ConstProp.diff
@@ -20,7 +20,7 @@
           _1 = encode(move _2) -> bb1;     // scope 0 at $DIR/issue-66971.rs:16:5: 16:23
                                            // mir::Constant
                                            // + span: $DIR/issue-66971.rs:16:5: 16:11
-                                           // + literal: Const { ty: fn(((), u8, u8)) {encode}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(((), u8, u8)) {encode}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/issue_67019.main.ConstProp.diff b/src/test/mir-opt/const_prop/issue_67019.main.ConstProp.diff
index 69d31b681b4e5..149a60c0bbb54 100644
--- a/src/test/mir-opt/const_prop/issue_67019.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/issue_67019.main.ConstProp.diff
@@ -21,7 +21,7 @@
           _1 = test(move _2) -> bb1;       // scope 0 at $DIR/issue-67019.rs:11:5: 11:20
                                            // mir::Constant
                                            // + span: $DIR/issue-67019.rs:11:5: 11:9
-                                           // + literal: Const { ty: fn(((u8, u8),)) {test}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(((u8, u8),)) {test}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/mutable_variable_aggregate_partial_read.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable_aggregate_partial_read.main.ConstProp.diff
index 86fac1270d0fc..724cf096f5946 100644
--- a/src/test/mir-opt/const_prop/mutable_variable_aggregate_partial_read.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/mutable_variable_aggregate_partial_read.main.ConstProp.diff
@@ -17,7 +17,7 @@
           _1 = foo() -> bb1;               // scope 0 at $DIR/mutable_variable_aggregate_partial_read.rs:5:29: 5:34
                                            // mir::Constant
                                            // + span: $DIR/mutable_variable_aggregate_partial_read.rs:5:29: 5:32
-                                           // + literal: Const { ty: fn() -> (i32, i32) {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> (i32, i32) {foo}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/mutable_variable_unprop_assign.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable_unprop_assign.main.ConstProp.diff
index 247d8f32432c0..a22efa7eaf50a 100644
--- a/src/test/mir-opt/const_prop/mutable_variable_unprop_assign.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/mutable_variable_unprop_assign.main.ConstProp.diff
@@ -26,7 +26,7 @@
           _1 = foo() -> bb1;               // scope 0 at $DIR/mutable_variable_unprop_assign.rs:5:13: 5:18
                                            // mir::Constant
                                            // + span: $DIR/mutable_variable_unprop_assign.rs:5:13: 5:16
-                                           // + literal: Const { ty: fn() -> i32 {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> i32 {foo}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/reify_fn_ptr.main.ConstProp.diff b/src/test/mir-opt/const_prop/reify_fn_ptr.main.ConstProp.diff
index 037febdf3a579..80f461a4c02cf 100644
--- a/src/test/mir-opt/const_prop/reify_fn_ptr.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/reify_fn_ptr.main.ConstProp.diff
@@ -16,7 +16,7 @@
           _3 = main as fn() (Pointer(ReifyFnPointer)); // scope 0 at $DIR/reify_fn_ptr.rs:4:13: 4:17
                                            // mir::Constant
                                            // + span: $DIR/reify_fn_ptr.rs:4:13: 4:17
-                                           // + literal: Const { ty: fn() {main}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {main}, val: Value(<ZST>) }
           _2 = move _3 as usize (PointerExposeAddress); // scope 0 at $DIR/reify_fn_ptr.rs:4:13: 4:26
           StorageDead(_3);                 // scope 0 at $DIR/reify_fn_ptr.rs:4:25: 4:26
           _1 = move _2 as *const fn() (PointerFromExposedAddress); // scope 0 at $DIR/reify_fn_ptr.rs:4:13: 4:41
diff --git a/src/test/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff b/src/test/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff
index af48ff0b098e7..6343ee80a2562 100644
--- a/src/test/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff
@@ -21,7 +21,7 @@
 +         _2 = consume(const 1_u32) -> bb1; // scope 1 at $DIR/scalar_literal_propagation.rs:4:5: 4:15
                                            // mir::Constant
                                            // + span: $DIR/scalar_literal_propagation.rs:4:5: 4:12
-                                           // + literal: Const { ty: fn(u32) {consume}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(u32) {consume}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/const_prop/switch_int.main.ConstProp.diff b/src/test/mir-opt/const_prop/switch_int.main.ConstProp.diff
index f031a703a9d72..5dfa05a46d377 100644
--- a/src/test/mir-opt/const_prop/switch_int.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/switch_int.main.ConstProp.diff
@@ -16,14 +16,14 @@
           _0 = foo(const -1_i32) -> bb3;   // scope 0 at $DIR/switch_int.rs:9:14: 9:21
                                            // mir::Constant
                                            // + span: $DIR/switch_int.rs:9:14: 9:17
-                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(<ZST>) }
       }
   
       bb2: {
           _0 = foo(const 0_i32) -> bb3;    // scope 0 at $DIR/switch_int.rs:8:14: 8:20
                                            // mir::Constant
                                            // + span: $DIR/switch_int.rs:8:14: 8:17
-                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(<ZST>) }
       }
   
       bb3: {
diff --git a/src/test/mir-opt/const_prop/switch_int.main.SimplifyConstCondition-after-const-prop.diff b/src/test/mir-opt/const_prop/switch_int.main.SimplifyConstCondition-after-const-prop.diff
index f2b02551146eb..704b4bbe018d5 100644
--- a/src/test/mir-opt/const_prop/switch_int.main.SimplifyConstCondition-after-const-prop.diff
+++ b/src/test/mir-opt/const_prop/switch_int.main.SimplifyConstCondition-after-const-prop.diff
@@ -16,14 +16,14 @@
           _0 = foo(const -1_i32) -> bb3;   // scope 0 at $DIR/switch_int.rs:9:14: 9:21
                                            // mir::Constant
                                            // + span: $DIR/switch_int.rs:9:14: 9:17
-                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(<ZST>) }
       }
   
       bb2: {
           _0 = foo(const 0_i32) -> bb3;    // scope 0 at $DIR/switch_int.rs:8:14: 8:20
                                            // mir::Constant
                                            // + span: $DIR/switch_int.rs:8:14: 8:17
-                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(i32) {foo}, val: Value(<ZST>) }
       }
   
       bb3: {
diff --git a/src/test/mir-opt/const_prop/tuple_literal_propagation.main.ConstProp.diff b/src/test/mir-opt/const_prop/tuple_literal_propagation.main.ConstProp.diff
index 2bcd10f160b82..adb182314ac5e 100644
--- a/src/test/mir-opt/const_prop/tuple_literal_propagation.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/tuple_literal_propagation.main.ConstProp.diff
@@ -22,7 +22,7 @@
           _2 = consume(move _3) -> bb1;    // scope 1 at $DIR/tuple_literal_propagation.rs:5:5: 5:15
                                            // mir::Constant
                                            // + span: $DIR/tuple_literal_propagation.rs:5:5: 5:12
-                                           // + literal: Const { ty: fn((u32, u32)) {consume}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn((u32, u32)) {consume}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/dead-store-elimination/cycle.cycle.DeadStoreElimination.diff b/src/test/mir-opt/dead-store-elimination/cycle.cycle.DeadStoreElimination.diff
index 6037f89086dc1..5f8019ac975a3 100644
--- a/src/test/mir-opt/dead-store-elimination/cycle.cycle.DeadStoreElimination.diff
+++ b/src/test/mir-opt/dead-store-elimination/cycle.cycle.DeadStoreElimination.diff
@@ -28,7 +28,7 @@
           _5 = cond() -> bb2;              // scope 0 at $DIR/cycle.rs:12:11: 12:17
                                            // mir::Constant
                                            // + span: $DIR/cycle.rs:12:11: 12:15
-                                           // + literal: Const { ty: fn() -> bool {cond}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {cond}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff b/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
index 372b14eb7c92a..688015f68d37e 100644
--- a/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
+++ b/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
@@ -27,7 +27,7 @@
 +         _2 = transmute::<&str, &[u8]>(move _8) -> bb12; // scope 2 at $SRC_DIR/core/src/str/mod.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/str/mod.rs:LL:COL
-                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&str) -> &[u8] {transmute::<&str, &[u8]>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&str) -> &[u8] {transmute::<&str, &[u8]>}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/derefer_complex_case.main.Derefer.diff b/src/test/mir-opt/derefer_complex_case.main.Derefer.diff
index f5eabf8696796..571efc9117102 100644
--- a/src/test/mir-opt/derefer_complex_case.main.Derefer.diff
+++ b/src/test/mir-opt/derefer_complex_case.main.Derefer.diff
@@ -36,7 +36,7 @@
           _1 = <&[i32; 2] as IntoIterator>::into_iter(move _2) -> bb1; // scope 0 at $DIR/derefer_complex_case.rs:4:17: 4:26
                                            // mir::Constant
                                            // + span: $DIR/derefer_complex_case.rs:4:17: 4:26
-                                           // + literal: Const { ty: fn(&[i32; 2]) -> <&[i32; 2] as IntoIterator>::IntoIter {<&[i32; 2] as IntoIterator>::into_iter}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(&[i32; 2]) -> <&[i32; 2] as IntoIterator>::IntoIter {<&[i32; 2] as IntoIterator>::into_iter}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -56,7 +56,7 @@
           _7 = <std::slice::Iter<i32> as Iterator>::next(move _8) -> bb3; // scope 1 at $DIR/derefer_complex_case.rs:4:17: 4:26
                                            // mir::Constant
                                            // + span: $DIR/derefer_complex_case.rs:4:17: 4:26
-                                           // + literal: Const { ty: for<'r> fn(&'r mut std::slice::Iter<i32>) -> Option<<std::slice::Iter<i32> as Iterator>::Item> {<std::slice::Iter<i32> as Iterator>::next}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r mut std::slice::Iter<i32>) -> Option<<std::slice::Iter<i32> as Iterator>::Item> {<std::slice::Iter<i32> as Iterator>::next}, val: Value(<ZST>) }
       }
   
       bb3: {
@@ -77,7 +77,7 @@
           _6 = std::mem::drop::<i32>(move _13) -> bb7; // scope 2 at $DIR/derefer_complex_case.rs:4:29: 4:38
                                            // mir::Constant
                                            // + span: $DIR/derefer_complex_case.rs:4:29: 4:33
-                                           // + literal: Const { ty: fn(i32) {std::mem::drop::<i32>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(i32) {std::mem::drop::<i32>}, val: Value(<ZST>) }
       }
   
       bb5: {
diff --git a/src/test/mir-opt/derefer_inline_test.main.Derefer.diff b/src/test/mir-opt/derefer_inline_test.main.Derefer.diff
index e131adae2b683..09cce1c165442 100644
--- a/src/test/mir-opt/derefer_inline_test.main.Derefer.diff
+++ b/src/test/mir-opt/derefer_inline_test.main.Derefer.diff
@@ -19,7 +19,7 @@
           _4 = alloc::alloc::exchange_malloc(move _2, move _3) -> bb1; // scope 1 at $DIR/derefer_inline_test.rs:10:5: 10:12
                                            // mir::Constant
                                            // + span: $DIR/derefer_inline_test.rs:10:5: 10:12
-                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -28,7 +28,7 @@
           (*_5) = f() -> [return: bb2, unwind: bb5]; // scope 0 at $DIR/derefer_inline_test.rs:10:9: 10:12
                                            // mir::Constant
                                            // + span: $DIR/derefer_inline_test.rs:10:9: 10:10
-                                           // + literal: Const { ty: fn() -> Box<u32> {f}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> Box<u32> {f}, val: Value(<ZST>) }
       }
   
       bb2: {
@@ -59,7 +59,7 @@
           _6 = alloc::alloc::box_free::<Box<u32>, std::alloc::Global>(move (_5.0: std::ptr::Unique<std::boxed::Box<u32>>), move (_5.1: std::alloc::Global)) -> bb6; // scope 0 at $DIR/derefer_inline_test.rs:10:11: 10:12
                                            // mir::Constant
                                            // + span: $DIR/derefer_inline_test.rs:10:11: 10:12
-                                           // + literal: Const { ty: unsafe fn(Unique<Box<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Box<u32>, std::alloc::Global>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(Unique<Box<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Box<u32>, std::alloc::Global>}, val: Value(<ZST>) }
       }
   
       bb8 (cleanup): {
diff --git a/src/test/mir-opt/derefer_terminator_test.main.Derefer.diff b/src/test/mir-opt/derefer_terminator_test.main.Derefer.diff
index 8b91a65bf3d7d..cb110afe0190c 100644
--- a/src/test/mir-opt/derefer_terminator_test.main.Derefer.diff
+++ b/src/test/mir-opt/derefer_terminator_test.main.Derefer.diff
@@ -33,7 +33,7 @@
           _1 = foo() -> bb1;               // scope 0 at $DIR/derefer_terminator_test.rs:3:13: 3:18
                                            // mir::Constant
                                            // + span: $DIR/derefer_terminator_test.rs:3:13: 3:16
-                                           // + literal: Const { ty: fn() -> bool {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {foo}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -41,7 +41,7 @@
           _2 = foo() -> bb2;               // scope 1 at $DIR/derefer_terminator_test.rs:4:13: 4:18
                                            // mir::Constant
                                            // + span: $DIR/derefer_terminator_test.rs:4:13: 4:16
-                                           // + literal: Const { ty: fn() -> bool {foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {foo}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/dest-prop/branch.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/branch.main.DestinationPropagation.diff
index c3aa19e6c5f84..97fb7fce14e40 100644
--- a/src/test/mir-opt/dest-prop/branch.main.DestinationPropagation.diff
+++ b/src/test/mir-opt/dest-prop/branch.main.DestinationPropagation.diff
@@ -19,7 +19,7 @@
           _1 = val() -> bb1;               // scope 0 at $DIR/branch.rs:13:13: 13:18
                                            // mir::Constant
                                            // + span: $DIR/branch.rs:13:13: 13:16
-                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -28,7 +28,7 @@
           _3 = cond() -> bb2;              // scope 1 at $DIR/branch.rs:15:16: 15:22
                                            // mir::Constant
                                            // + span: $DIR/branch.rs:15:16: 15:20
-                                           // + literal: Const { ty: fn() -> bool {cond}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {cond}, val: Value(<ZST>) }
       }
   
       bb2: {
@@ -45,7 +45,7 @@
           _4 = val() -> bb5;               // scope 1 at $DIR/branch.rs:18:9: 18:14
                                            // mir::Constant
                                            // + span: $DIR/branch.rs:18:9: 18:12
-                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(<ZST>) }
       }
   
       bb5: {
diff --git a/src/test/mir-opt/dest-prop/copy_propagation_arg.bar.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/copy_propagation_arg.bar.DestinationPropagation.diff
index 3f9ba4ad4f0ac..11a0d1f609f72 100644
--- a/src/test/mir-opt/dest-prop/copy_propagation_arg.bar.DestinationPropagation.diff
+++ b/src/test/mir-opt/dest-prop/copy_propagation_arg.bar.DestinationPropagation.diff
@@ -14,7 +14,7 @@
           _2 = dummy(move _3) -> bb1;      // scope 0 at $DIR/copy_propagation_arg.rs:16:5: 16:13
                                            // mir::Constant
                                            // + span: $DIR/copy_propagation_arg.rs:16:5: 16:10
-                                           // + literal: Const { ty: fn(u8) -> u8 {dummy}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(u8) -> u8 {dummy}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/dest-prop/copy_propagation_arg.foo.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/copy_propagation_arg.foo.DestinationPropagation.diff
index 963881d7ae062..1346a04938a20 100644
--- a/src/test/mir-opt/dest-prop/copy_propagation_arg.foo.DestinationPropagation.diff
+++ b/src/test/mir-opt/dest-prop/copy_propagation_arg.foo.DestinationPropagation.diff
@@ -14,7 +14,7 @@
           _2 = dummy(move _3) -> bb1;      // scope 0 at $DIR/copy_propagation_arg.rs:11:9: 11:17
                                            // mir::Constant
                                            // + span: $DIR/copy_propagation_arg.rs:11:9: 11:14
-                                           // + literal: Const { ty: fn(u8) -> u8 {dummy}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(u8) -> u8 {dummy}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/dest-prop/cycle.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/cycle.main.DestinationPropagation.diff
index 8e44d68d9348e..516180fbec68d 100644
--- a/src/test/mir-opt/dest-prop/cycle.main.DestinationPropagation.diff
+++ b/src/test/mir-opt/dest-prop/cycle.main.DestinationPropagation.diff
@@ -27,7 +27,7 @@
           _1 = val() -> bb1;               // scope 0 at $DIR/cycle.rs:9:17: 9:22
                                            // mir::Constant
                                            // + span: $DIR/cycle.rs:9:17: 9:20
-                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> i32 {val}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/dest-prop/union.main.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/union.main.DestinationPropagation.diff
index 582a1738cbf96..acfd3c18fc930 100644
--- a/src/test/mir-opt/dest-prop/union.main.DestinationPropagation.diff
+++ b/src/test/mir-opt/dest-prop/union.main.DestinationPropagation.diff
@@ -22,7 +22,7 @@
           _2 = val() -> bb1;               // scope 0 at $DIR/union.rs:13:23: 13:28
                                            // mir::Constant
                                            // + span: $DIR/union.rs:13:23: 13:26
-                                           // + literal: Const { ty: fn() -> u32 {val}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> u32 {val}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff b/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
index 15409fa0dd23c..a930d83b9e798 100644
--- a/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
+++ b/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
@@ -41,7 +41,7 @@
           _4 = Formatter::sign_plus(move _5) -> bb1; // scope 0 at $DIR/funky_arms.rs:15:22: 15:37
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:15:26: 15:35
-                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> bool {Formatter::sign_plus}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> bool {Formatter::sign_plus}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -69,7 +69,7 @@
           _7 = Formatter::precision(move _8) -> bb5; // scope 3 at $DIR/funky_arms.rs:24:30: 24:45
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:24:34: 24:43
-                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> Option<usize> {Formatter::precision}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> Option<usize> {Formatter::precision}, val: Value(<ZST>) }
       }
   
       bb5: {
@@ -100,7 +100,7 @@
           _0 = float_to_exponential_common_exact::<T>(move _11, move _12, move _13, move _14, move _17) -> bb7; // scope 3 at $DIR/funky_arms.rs:26:9: 26:87
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:26:9: 26:42
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, u32, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_exact::<T>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, u32, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_exact::<T>}, val: Value(<ZST>) }
       }
   
       bb7: {
@@ -125,7 +125,7 @@
           _0 = float_to_exponential_common_shortest::<T>(move _18, move _19, move _20, move _21) -> bb9; // scope 2 at $DIR/funky_arms.rs:28:9: 28:68
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:28:9: 28:45
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_shortest::<T>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_shortest::<T>}, val: Value(<ZST>) }
       }
   
       bb9: {
diff --git a/src/test/mir-opt/generator_storage_dead_unwind.main-{closure#0}.StateTransform.before.mir b/src/test/mir-opt/generator_storage_dead_unwind.main-{closure#0}.StateTransform.before.mir
index 739492d7d249f..a184b55b6d1ec 100644
--- a/src/test/mir-opt/generator_storage_dead_unwind.main-{closure#0}.StateTransform.before.mir
+++ b/src/test/mir-opt/generator_storage_dead_unwind.main-{closure#0}.StateTransform.before.mir
@@ -41,7 +41,7 @@ yields ()
         _7 = take::<Foo>(move _8) -> [return: bb2, unwind: bb9]; // scope 2 at $DIR/generator-storage-dead-unwind.rs:26:9: 26:16
                                          // mir::Constant
                                          // + span: $DIR/generator-storage-dead-unwind.rs:26:9: 26:13
-                                         // + literal: Const { ty: fn(Foo) {take::<Foo>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Foo) {take::<Foo>}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -53,7 +53,7 @@ yields ()
         _9 = take::<Bar>(move _10) -> [return: bb3, unwind: bb8]; // scope 2 at $DIR/generator-storage-dead-unwind.rs:27:9: 27:16
                                          // mir::Constant
                                          // + span: $DIR/generator-storage-dead-unwind.rs:27:9: 27:13
-                                         // + literal: Const { ty: fn(Bar) {take::<Bar>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Bar) {take::<Bar>}, val: Value(<ZST>) }
     }
 
     bb3: {
diff --git a/src/test/mir-opt/generator_tiny.main-{closure#0}.generator_resume.0.mir b/src/test/mir-opt/generator_tiny.main-{closure#0}.generator_resume.0.mir
index 7f5ebe2a59b55..53ce6a037c4a4 100644
--- a/src/test/mir-opt/generator_tiny.main-{closure#0}.generator_resume.0.mir
+++ b/src/test/mir-opt/generator_tiny.main-{closure#0}.generator_resume.0.mir
@@ -61,7 +61,7 @@ fn main::{closure#0}(_1: Pin<&mut [generator@$DIR/generator-tiny.rs:19:16: 25:6]
         _8 = callee() -> bb4;            // scope 1 at $DIR/generator-tiny.rs:23:13: 23:21
                                          // mir::Constant
                                          // + span: $DIR/generator-tiny.rs:23:13: 23:19
-                                         // + literal: Const { ty: fn() {callee}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {callee}, val: Value(<ZST>) }
     }
 
     bb4: {
diff --git a/src/test/mir-opt/inline/caller_with_trivial_bound.foo.Inline.diff b/src/test/mir-opt/inline/caller_with_trivial_bound.foo.Inline.diff
index 5d236373a4ce0..d30c74897b342 100644
--- a/src/test/mir-opt/inline/caller_with_trivial_bound.foo.Inline.diff
+++ b/src/test/mir-opt/inline/caller_with_trivial_bound.foo.Inline.diff
@@ -13,7 +13,7 @@
           _1 = bar::<T>() -> bb1;          // scope 0 at $DIR/caller-with-trivial-bound.rs:20:51: 20:61
                                            // mir::Constant
                                            // + span: $DIR/caller-with-trivial-bound.rs:20:51: 20:59
-                                           // + literal: Const { ty: fn() -> <IntFactory as Factory<T>>::Item {bar::<T>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> <IntFactory as Factory<T>>::Item {bar::<T>}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/cycle.f.Inline.diff b/src/test/mir-opt/inline/cycle.f.Inline.diff
index d42b8397c505e..1376ba99d992c 100644
--- a/src/test/mir-opt/inline/cycle.f.Inline.diff
+++ b/src/test/mir-opt/inline/cycle.f.Inline.diff
@@ -17,7 +17,7 @@
           _2 = <impl Fn() as Fn<()>>::call(move _3, move _4) -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/cycle.rs:6:5: 6:8
                                            // mir::Constant
                                            // + span: $DIR/cycle.rs:6:5: 6:6
-                                           // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/cycle.g.Inline.diff b/src/test/mir-opt/inline/cycle.g.Inline.diff
index 450157e64284f..5a8c147a32723 100644
--- a/src/test/mir-opt/inline/cycle.g.Inline.diff
+++ b/src/test/mir-opt/inline/cycle.g.Inline.diff
@@ -5,11 +5,11 @@
       let mut _0: ();                      // return place in scope 0 at $DIR/cycle.rs:11:8: 11:8
       let _1: ();                          // in scope 0 at $DIR/cycle.rs:12:5: 12:12
 +     let mut _2: fn() {main};             // in scope 0 at $DIR/cycle.rs:12:5: 12:12
-+     let mut _5: ();                      // in scope 0 at $DIR/cycle.rs:6:5: 6:8
 +     scope 1 (inlined f::<fn() {main}>) { // at $DIR/cycle.rs:12:5: 12:12
 +         debug g => _2;                   // in scope 1 at $DIR/cycle.rs:5:6: 5:7
 +         let _3: ();                      // in scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         let mut _4: &fn() {main};        // in scope 1 at $DIR/cycle.rs:6:5: 6:6
++         let mut _5: ();                  // in scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         scope 2 (inlined <fn() {main} as Fn<()>>::call - shim(fn() {main})) { // at $DIR/cycle.rs:6:5: 6:8
 +         }
 +     }
@@ -21,15 +21,14 @@
 +         _2 = main;                       // scope 0 at $DIR/cycle.rs:12:5: 12:12
                                            // mir::Constant
 -                                          // + span: $DIR/cycle.rs:12:5: 12:6
--                                          // + literal: Const { ty: fn(fn() {main}) {f::<fn() {main}>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn(fn() {main}) {f::<fn() {main}>}, val: Value(<ZST>) }
 -                                          // mir::Constant
                                            // + span: $DIR/cycle.rs:12:7: 12:11
-                                           // + literal: Const { ty: fn() {main}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {main}, val: Value(<ZST>) }
 +         StorageLive(_3);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         StorageLive(_4);                 // scope 1 at $DIR/cycle.rs:6:5: 6:6
 +         _4 = &_2;                        // scope 1 at $DIR/cycle.rs:6:5: 6:6
 +         StorageLive(_5);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
-+         _5 = const ();                   // scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         _3 = move (*_4)() -> [return: bb4, unwind: bb2]; // scope 2 at $SRC_DIR/core/src/ops/function.rs:LL:COL
       }
   
@@ -49,7 +48,7 @@
 +     }
 + 
 +     bb4: {
-+         StorageDead(_5);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
++         StorageDead(_5);                 // scope 1 at $DIR/cycle.rs:6:7: 6:8
 +         StorageDead(_4);                 // scope 1 at $DIR/cycle.rs:6:7: 6:8
 +         StorageDead(_3);                 // scope 1 at $DIR/cycle.rs:6:8: 6:9
 +         drop(_2) -> bb1;                 // scope 1 at $DIR/cycle.rs:7:1: 7:2
diff --git a/src/test/mir-opt/inline/cycle.main.Inline.diff b/src/test/mir-opt/inline/cycle.main.Inline.diff
index 5e2f70799e41e..e102c65090587 100644
--- a/src/test/mir-opt/inline/cycle.main.Inline.diff
+++ b/src/test/mir-opt/inline/cycle.main.Inline.diff
@@ -5,11 +5,11 @@
       let mut _0: ();                      // return place in scope 0 at $DIR/cycle.rs:16:11: 16:11
       let _1: ();                          // in scope 0 at $DIR/cycle.rs:17:5: 17:9
 +     let mut _2: fn() {g};                // in scope 0 at $DIR/cycle.rs:17:5: 17:9
-+     let mut _5: ();                      // in scope 0 at $DIR/cycle.rs:6:5: 6:8
 +     scope 1 (inlined f::<fn() {g}>) {    // at $DIR/cycle.rs:17:5: 17:9
 +         debug g => _2;                   // in scope 1 at $DIR/cycle.rs:5:6: 5:7
 +         let _3: ();                      // in scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         let mut _4: &fn() {g};           // in scope 1 at $DIR/cycle.rs:6:5: 6:6
++         let mut _5: ();                  // in scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         scope 2 (inlined <fn() {g} as Fn<()>>::call - shim(fn() {g})) { // at $DIR/cycle.rs:6:5: 6:8
 +             scope 3 (inlined g) {        // at $SRC_DIR/core/src/ops/function.rs:LL:COL
 +                 let mut _6: fn() {main}; // in scope 3 at $DIR/cycle.rs:12:5: 12:12
@@ -31,15 +31,14 @@
 +         _2 = g;                          // scope 0 at $DIR/cycle.rs:17:5: 17:9
                                            // mir::Constant
 -                                          // + span: $DIR/cycle.rs:17:5: 17:6
--                                          // + literal: Const { ty: fn(fn() {g}) {f::<fn() {g}>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn(fn() {g}) {f::<fn() {g}>}, val: Value(<ZST>) }
 -                                          // mir::Constant
                                            // + span: $DIR/cycle.rs:17:7: 17:8
-                                           // + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {g}, val: Value(<ZST>) }
 +         StorageLive(_3);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         StorageLive(_4);                 // scope 1 at $DIR/cycle.rs:6:5: 6:6
 +         _4 = &_2;                        // scope 1 at $DIR/cycle.rs:6:5: 6:6
 +         StorageLive(_5);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
-+         _5 = const ();                   // scope 1 at $DIR/cycle.rs:6:5: 6:8
 +         StorageLive(_6);                 // scope 3 at $DIR/cycle.rs:12:5: 12:12
 +         StorageLive(_7);                 // scope 4 at $DIR/cycle.rs:6:5: 6:8
 +         StorageLive(_8);                 // scope 4 at $DIR/cycle.rs:6:5: 6:6
@@ -66,7 +65,7 @@
 +         StorageDead(_8);                 // scope 4 at $DIR/cycle.rs:6:7: 6:8
 +         StorageDead(_7);                 // scope 4 at $DIR/cycle.rs:6:8: 6:9
 +         StorageDead(_6);                 // scope 3 at $DIR/cycle.rs:12:5: 12:12
-+         StorageDead(_5);                 // scope 1 at $DIR/cycle.rs:6:5: 6:8
++         StorageDead(_5);                 // scope 1 at $DIR/cycle.rs:6:7: 6:8
 +         StorageDead(_4);                 // scope 1 at $DIR/cycle.rs:6:7: 6:8
 +         StorageDead(_3);                 // scope 1 at $DIR/cycle.rs:6:8: 6:9
 +         drop(_2) -> bb1;                 // scope 1 at $DIR/cycle.rs:7:1: 7:2
diff --git a/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff b/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff
index d1ab29b8a21ab..7b306dd9482ca 100644
--- a/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff
+++ b/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff
@@ -28,7 +28,7 @@
                                            // mir::Constant
                                            // + span: $DIR/dyn-trait.rs:33:13: 33:21
                                            // + user_ty: UserType(0)
-                                           // + literal: Const { ty: for<'r> fn(&'r T) -> &'r <Q as Query>::C {<Q as Query>::cache::<T>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r T) -> &'r <Q as Query>::C {<Q as Query>::cache::<T>}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -46,9 +46,9 @@
 +         _0 = <dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache(move _7) -> bb2; // scope 3 at $DIR/dyn-trait.rs:21:5: 21:22
                                            // mir::Constant
 -                                          // + span: $DIR/dyn-trait.rs:34:5: 34:22
--                                          // + literal: Const { ty: for<'r> fn(&'r <Q as Query>::C) {try_execute_query::<<Q as Query>::C>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r <Q as Query>::C) {try_execute_query::<<Q as Query>::C>}, val: Value(<ZST>) }
 +                                          // + span: $DIR/dyn-trait.rs:21:7: 21:20
-+                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <Q as Query>::V>) {<dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache}, val: Value(Scalar(<ZST>)) }
++                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <Q as Query>::V>) {<dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff b/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff
index 27309328052c7..2a909702a6dc0 100644
--- a/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff
+++ b/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff
@@ -12,7 +12,7 @@
           _0 = <dyn Cache<V = V> as Cache>::store_nocache(move _2) -> bb1; // scope 0 at $DIR/dyn-trait.rs:21:5: 21:22
                                            // mir::Constant
                                            // + span: $DIR/dyn-trait.rs:21:7: 21:20
-                                           // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = V>) {<dyn Cache<V = V> as Cache>::store_nocache}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = V>) {<dyn Cache<V = V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff b/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff
index 0c44c3ada0f8c..01ebc999cb3ec 100644
--- a/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff
+++ b/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff
@@ -23,9 +23,9 @@
 +         _0 = <dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache(move _4) -> bb1; // scope 1 at $DIR/dyn-trait.rs:21:5: 21:22
                                            // mir::Constant
 -                                          // + span: $DIR/dyn-trait.rs:27:5: 27:13
--                                          // + literal: Const { ty: for<'r> fn(&'r (dyn Cache<V = <C as Cache>::V> + 'r)) {mk_cycle::<<C as Cache>::V>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r (dyn Cache<V = <C as Cache>::V> + 'r)) {mk_cycle::<<C as Cache>::V>}, val: Value(<ZST>) }
 +                                          // + span: $DIR/dyn-trait.rs:21:7: 21:20
-+                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <C as Cache>::V>) {<dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache}, val: Value(Scalar(<ZST>)) }
++                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <C as Cache>::V>) {<dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_any_operand.bar.Inline.after.mir b/src/test/mir-opt/inline/inline_any_operand.bar.Inline.after.mir
index ade6ccfc7f144..ff338ae58cd87 100644
--- a/src/test/mir-opt/inline/inline_any_operand.bar.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_any_operand.bar.Inline.after.mir
@@ -21,7 +21,7 @@ fn bar() -> bool {
         _1 = foo;                        // scope 0 at $DIR/inline-any-operand.rs:11:13: 11:16
                                          // mir::Constant
                                          // + span: $DIR/inline-any-operand.rs:11:13: 11:16
-                                         // + literal: Const { ty: fn(i32, i32) -> bool {foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(i32, i32) -> bool {foo}, val: Value(<ZST>) }
         StorageLive(_2);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:6
         _2 = _1;                         // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:6
         StorageLive(_3);                 // scope 1 at $DIR/inline-any-operand.rs:12:5: 12:13
diff --git a/src/test/mir-opt/inline/inline_compatibility.inlined_no_sanitize.Inline.diff b/src/test/mir-opt/inline/inline_compatibility.inlined_no_sanitize.Inline.diff
index fd9a540ca16e2..34762b97c3b2f 100644
--- a/src/test/mir-opt/inline/inline_compatibility.inlined_no_sanitize.Inline.diff
+++ b/src/test/mir-opt/inline/inline_compatibility.inlined_no_sanitize.Inline.diff
@@ -12,7 +12,7 @@
 -         _1 = no_sanitize() -> bb1;       // scope 0 at $DIR/inline-compatibility.rs:24:5: 24:18
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-compatibility.rs:24:5: 24:16
--                                          // + literal: Const { ty: unsafe fn() {no_sanitize}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn() {no_sanitize}, val: Value(<ZST>) }
 -     }
 - 
 -     bb1: {
diff --git a/src/test/mir-opt/inline/inline_compatibility.inlined_target_feature.Inline.diff b/src/test/mir-opt/inline/inline_compatibility.inlined_target_feature.Inline.diff
index e7db7aa382fae..fd1e1983d1e0d 100644
--- a/src/test/mir-opt/inline/inline_compatibility.inlined_target_feature.Inline.diff
+++ b/src/test/mir-opt/inline/inline_compatibility.inlined_target_feature.Inline.diff
@@ -12,7 +12,7 @@
 -         _1 = target_feature() -> bb1;    // scope 0 at $DIR/inline-compatibility.rs:13:5: 13:21
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-compatibility.rs:13:5: 13:19
--                                          // + literal: Const { ty: unsafe fn() {target_feature}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn() {target_feature}, val: Value(<ZST>) }
 -     }
 - 
 -     bb1: {
diff --git a/src/test/mir-opt/inline/inline_compatibility.not_inlined_c_variadic.Inline.diff b/src/test/mir-opt/inline/inline_compatibility.not_inlined_c_variadic.Inline.diff
index 09bca903c80e8..bced3f6fe56a7 100644
--- a/src/test/mir-opt/inline/inline_compatibility.not_inlined_c_variadic.Inline.diff
+++ b/src/test/mir-opt/inline/inline_compatibility.not_inlined_c_variadic.Inline.diff
@@ -13,7 +13,7 @@
           _1 = sum(const 4_u32, const 4_u32, const 30_u32, const 200_u32, const 1000_u32) -> bb1; // scope 0 at $DIR/inline-compatibility.rs:42:13: 42:52
                                            // mir::Constant
                                            // + span: $DIR/inline-compatibility.rs:42:13: 42:16
-                                           // + literal: Const { ty: unsafe extern "C" fn(u32, ...) -> u32 {sum}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe extern "C" fn(u32, ...) -> u32 {sum}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_compatibility.not_inlined_no_sanitize.Inline.diff b/src/test/mir-opt/inline/inline_compatibility.not_inlined_no_sanitize.Inline.diff
index 5af3946f2e501..a4989cbfa096d 100644
--- a/src/test/mir-opt/inline/inline_compatibility.not_inlined_no_sanitize.Inline.diff
+++ b/src/test/mir-opt/inline/inline_compatibility.not_inlined_no_sanitize.Inline.diff
@@ -10,7 +10,7 @@
           _1 = no_sanitize() -> bb1;       // scope 0 at $DIR/inline-compatibility.rs:29:5: 29:18
                                            // mir::Constant
                                            // + span: $DIR/inline-compatibility.rs:29:5: 29:16
-                                           // + literal: Const { ty: unsafe fn() {no_sanitize}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn() {no_sanitize}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_compatibility.not_inlined_target_feature.Inline.diff b/src/test/mir-opt/inline/inline_compatibility.not_inlined_target_feature.Inline.diff
index 8c9fa573ce218..49dd90c971cb4 100644
--- a/src/test/mir-opt/inline/inline_compatibility.not_inlined_target_feature.Inline.diff
+++ b/src/test/mir-opt/inline/inline_compatibility.not_inlined_target_feature.Inline.diff
@@ -10,7 +10,7 @@
           _1 = target_feature() -> bb1;    // scope 0 at $DIR/inline-compatibility.rs:18:5: 18:21
                                            // mir::Constant
                                            // + span: $DIR/inline-compatibility.rs:18:5: 18:19
-                                           // + literal: Const { ty: unsafe fn() {target_feature}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn() {target_feature}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_cycle.one.Inline.diff b/src/test/mir-opt/inline/inline_cycle.one.Inline.diff
index 3b32cb809113e..8128797d27eae 100644
--- a/src/test/mir-opt/inline/inline_cycle.one.Inline.diff
+++ b/src/test/mir-opt/inline/inline_cycle.one.Inline.diff
@@ -18,7 +18,7 @@
                                            // mir::Constant
 -                                          // + span: $DIR/inline-cycle.rs:14:5: 14:22
 +                                          // + span: $DIR/inline-cycle.rs:36:9: 36:26
-                                           // + literal: Const { ty: fn() {<C as Call>::call}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {<C as Call>::call}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_cycle.two.Inline.diff b/src/test/mir-opt/inline/inline_cycle.two.Inline.diff
index c7f8a64afcd8d..29c793d7bd8cd 100644
--- a/src/test/mir-opt/inline/inline_cycle.two.Inline.diff
+++ b/src/test/mir-opt/inline/inline_cycle.two.Inline.diff
@@ -5,11 +5,11 @@
       let mut _0: ();                      // return place in scope 0 at $DIR/inline-cycle.rs:48:10: 48:10
       let _1: ();                          // in scope 0 at $DIR/inline-cycle.rs:49:5: 49:12
 +     let mut _2: fn() {f};                // in scope 0 at $DIR/inline-cycle.rs:49:5: 49:12
-+     let mut _5: ();                      // in scope 0 at $DIR/inline-cycle.rs:54:5: 54:8
 +     scope 1 (inlined call::<fn() {f}>) { // at $DIR/inline-cycle.rs:49:5: 49:12
 +         debug f => _2;                   // in scope 1 at $DIR/inline-cycle.rs:53:22: 53:23
 +         let _3: ();                      // in scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
 +         let mut _4: fn() {f};            // in scope 1 at $DIR/inline-cycle.rs:54:5: 54:6
++         let mut _5: ();                  // in scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
 +         scope 2 (inlined <fn() {f} as FnOnce<()>>::call_once - shim(fn() {f})) { // at $DIR/inline-cycle.rs:54:5: 54:8
 +             scope 3 (inlined f) {        // at $SRC_DIR/core/src/ops/function.rs:LL:COL
 +                 let _6: ();              // in scope 3 at $DIR/inline-cycle.rs:59:5: 59:12
@@ -25,26 +25,25 @@
                                            // mir::Constant
 -                                          // + span: $DIR/inline-cycle.rs:49:5: 49:9
 +                                          // + span: $DIR/inline-cycle.rs:49:10: 49:11
-+                                          // + literal: Const { ty: fn() {f}, val: Value(Scalar(<ZST>)) }
++                                          // + literal: Const { ty: fn() {f}, val: Value(<ZST>) }
 +         StorageLive(_3);                 // scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
 +         StorageLive(_4);                 // scope 1 at $DIR/inline-cycle.rs:54:5: 54:6
 +         _4 = move _2;                    // scope 1 at $DIR/inline-cycle.rs:54:5: 54:6
 +         StorageLive(_5);                 // scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
-+         _5 = const ();                   // scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
 +         StorageLive(_6);                 // scope 3 at $DIR/inline-cycle.rs:59:5: 59:12
 +         _6 = call::<fn() {f}>(f) -> bb1; // scope 3 at $DIR/inline-cycle.rs:59:5: 59:12
 +                                          // mir::Constant
 +                                          // + span: $DIR/inline-cycle.rs:59:5: 59:9
-                                           // + literal: Const { ty: fn(fn() {f}) {call::<fn() {f}>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(fn() {f}) {call::<fn() {f}>}, val: Value(<ZST>) }
                                            // mir::Constant
 -                                          // + span: $DIR/inline-cycle.rs:49:10: 49:11
 +                                          // + span: $DIR/inline-cycle.rs:59:10: 59:11
-                                           // + literal: Const { ty: fn() {f}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {f}, val: Value(<ZST>) }
       }
   
       bb1: {
 +         StorageDead(_6);                 // scope 3 at $DIR/inline-cycle.rs:59:12: 59:13
-+         StorageDead(_5);                 // scope 1 at $DIR/inline-cycle.rs:54:5: 54:8
++         StorageDead(_5);                 // scope 1 at $DIR/inline-cycle.rs:54:7: 54:8
 +         StorageDead(_4);                 // scope 1 at $DIR/inline-cycle.rs:54:7: 54:8
 +         StorageDead(_3);                 // scope 1 at $DIR/inline-cycle.rs:54:8: 54:9
 +         StorageDead(_2);                 // scope 0 at $DIR/inline-cycle.rs:49:5: 49:12
diff --git a/src/test/mir-opt/inline/inline_cycle_generic.main.Inline.diff b/src/test/mir-opt/inline/inline_cycle_generic.main.Inline.diff
index 2a19b21510a10..2ccd39e7931ed 100644
--- a/src/test/mir-opt/inline/inline_cycle_generic.main.Inline.diff
+++ b/src/test/mir-opt/inline/inline_cycle_generic.main.Inline.diff
@@ -20,7 +20,7 @@
                                            // mir::Constant
 -                                          // + span: $DIR/inline-cycle-generic.rs:9:5: 9:22
 +                                          // + span: $DIR/inline-cycle-generic.rs:31:9: 31:26
-                                           // + literal: Const { ty: fn() {<C as Call>::call}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {<C as Call>::call}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/inline/inline_diverging.f.Inline.diff b/src/test/mir-opt/inline/inline_diverging.f.Inline.diff
index ff25c5b4bc337..7cdc1a6b546a2 100644
--- a/src/test/mir-opt/inline/inline_diverging.f.Inline.diff
+++ b/src/test/mir-opt/inline/inline_diverging.f.Inline.diff
@@ -13,7 +13,7 @@
 -         _2 = sleep();                    // scope 0 at $DIR/inline-diverging.rs:8:5: 8:12
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-diverging.rs:8:5: 8:10
--                                          // + literal: Const { ty: fn() -> ! {sleep}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> ! {sleep}, val: Value(<ZST>) }
 +         goto -> bb1;                     // scope 0 at $DIR/inline-diverging.rs:8:5: 8:12
 +     }
 + 
diff --git a/src/test/mir-opt/inline/inline_diverging.g.Inline.diff b/src/test/mir-opt/inline/inline_diverging.g.Inline.diff
index da55260e284ea..595df0aed5ff8 100644
--- a/src/test/mir-opt/inline/inline_diverging.g.Inline.diff
+++ b/src/test/mir-opt/inline/inline_diverging.g.Inline.diff
@@ -38,9 +38,9 @@
 +         _7 = begin_panic::<&str>(const "explicit panic"); // scope 1 at $SRC_DIR/std/src/panic.rs:LL:COL
                                            // mir::Constant
 -                                          // + span: $DIR/inline-diverging.rs:16:9: 16:14
--                                          // + literal: Const { ty: fn() -> ! {panic}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> ! {panic}, val: Value(<ZST>) }
 +                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-+                                          // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
++                                          // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(<ZST>) }
 +                                          // mir::Constant
 +                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
 +                                          // + literal: Const { ty: &str, val: Value(Slice(..)) }
diff --git a/src/test/mir-opt/inline/inline_diverging.h.Inline.diff b/src/test/mir-opt/inline/inline_diverging.h.Inline.diff
index 0a19daa5045c9..32066cf2e3e73 100644
--- a/src/test/mir-opt/inline/inline_diverging.h.Inline.diff
+++ b/src/test/mir-opt/inline/inline_diverging.h.Inline.diff
@@ -5,20 +5,20 @@
       let mut _0: ();                      // return place in scope 0 at $DIR/inline-diverging.rs:21:12: 21:12
       let _1: (!, !);                      // in scope 0 at $DIR/inline-diverging.rs:22:5: 22:22
 +     let mut _2: fn() -> ! {sleep};       // in scope 0 at $DIR/inline-diverging.rs:22:5: 22:22
-+     let mut _9: ();                      // in scope 0 at $DIR/inline-diverging.rs:27:13: 27:16
-+     let mut _10: ();                     // in scope 0 at $DIR/inline-diverging.rs:28:13: 28:16
 +     scope 1 (inlined call_twice::<!, fn() -> ! {sleep}>) { // at $DIR/inline-diverging.rs:22:5: 22:22
 +         debug f => _2;                   // in scope 1 at $DIR/inline-diverging.rs:26:36: 26:37
 +         let _3: !;                       // in scope 1 at $DIR/inline-diverging.rs:27:9: 27:10
 +         let mut _4: &fn() -> ! {sleep};  // in scope 1 at $DIR/inline-diverging.rs:27:13: 27:14
-+         let mut _6: &fn() -> ! {sleep};  // in scope 1 at $DIR/inline-diverging.rs:28:13: 28:14
-+         let mut _7: !;                   // in scope 1 at $DIR/inline-diverging.rs:29:6: 29:7
-+         let mut _8: !;                   // in scope 1 at $DIR/inline-diverging.rs:29:9: 29:10
++         let mut _5: ();                  // in scope 1 at $DIR/inline-diverging.rs:27:13: 27:16
++         let mut _7: &fn() -> ! {sleep};  // in scope 1 at $DIR/inline-diverging.rs:28:13: 28:14
++         let mut _8: ();                  // in scope 1 at $DIR/inline-diverging.rs:28:13: 28:16
++         let mut _9: !;                   // in scope 1 at $DIR/inline-diverging.rs:29:6: 29:7
++         let mut _10: !;                  // in scope 1 at $DIR/inline-diverging.rs:29:9: 29:10
 +         scope 2 {
 +             debug a => _3;               // in scope 2 at $DIR/inline-diverging.rs:27:9: 27:10
-+             let _5: !;                   // in scope 2 at $DIR/inline-diverging.rs:28:9: 28:10
++             let _6: !;                   // in scope 2 at $DIR/inline-diverging.rs:28:9: 28:10
 +             scope 3 {
-+                 debug b => _5;           // in scope 3 at $DIR/inline-diverging.rs:28:9: 28:10
++                 debug b => _6;           // in scope 3 at $DIR/inline-diverging.rs:28:9: 28:10
 +             }
 +             scope 6 (inlined <fn() -> ! {sleep} as Fn<()>>::call - shim(fn() -> ! {sleep})) { // at $DIR/inline-diverging.rs:28:13: 28:16
 +                 scope 7 (inlined sleep) { // at $SRC_DIR/core/src/ops/function.rs:LL:COL
@@ -38,15 +38,14 @@
 +         _2 = sleep;                      // scope 0 at $DIR/inline-diverging.rs:22:5: 22:22
                                            // mir::Constant
 -                                          // + span: $DIR/inline-diverging.rs:22:5: 22:15
--                                          // + literal: Const { ty: fn(fn() -> ! {sleep}) -> (!, !) {call_twice::<!, fn() -> ! {sleep}>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn(fn() -> ! {sleep}) -> (!, !) {call_twice::<!, fn() -> ! {sleep}>}, val: Value(<ZST>) }
 -                                          // mir::Constant
                                            // + span: $DIR/inline-diverging.rs:22:16: 22:21
-                                           // + literal: Const { ty: fn() -> ! {sleep}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> ! {sleep}, val: Value(<ZST>) }
 +         StorageLive(_3);                 // scope 1 at $DIR/inline-diverging.rs:27:9: 27:10
 +         StorageLive(_4);                 // scope 1 at $DIR/inline-diverging.rs:27:13: 27:14
 +         _4 = &_2;                        // scope 1 at $DIR/inline-diverging.rs:27:13: 27:14
-+         StorageLive(_9);                 // scope 1 at $DIR/inline-diverging.rs:27:13: 27:16
-+         _9 = const ();                   // scope 1 at $DIR/inline-diverging.rs:27:13: 27:16
++         StorageLive(_5);                 // scope 1 at $DIR/inline-diverging.rs:27:13: 27:16
 +         goto -> bb1;                     // scope 5 at $DIR/inline-diverging.rs:39:5: 39:12
 +     }
 + 
diff --git a/src/test/mir-opt/inline/inline_generator.main.Inline.diff b/src/test/mir-opt/inline/inline_generator.main.Inline.diff
index 3e1c4a4670143..3bc516ea808c7 100644
--- a/src/test/mir-opt/inline/inline_generator.main.Inline.diff
+++ b/src/test/mir-opt/inline/inline_generator.main.Inline.diff
@@ -43,7 +43,7 @@
 -         _4 = g() -> bb1;                 // scope 0 at $DIR/inline-generator.rs:9:28: 9:31
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-generator.rs:9:28: 9:29
--                                          // + literal: Const { ty: fn() -> impl Generator<bool> {g}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> impl Generator<bool> {g}, val: Value(<ZST>) }
 -     }
 - 
 -     bb1: {
@@ -54,7 +54,7 @@
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-generator.rs:9:14: 9:22
 -                                          // + user_ty: UserType(0)
--                                          // + literal: Const { ty: fn(&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]) -> Pin<&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]> {Pin::<&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]>::new}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn(&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]) -> Pin<&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]> {Pin::<&mut [generator@$DIR/inline-generator.rs:15:5: 15:41]>::new}, val: Value(<ZST>) }
 -     }
 - 
 -     bb2: {
@@ -70,7 +70,7 @@
 -         _1 = <[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::resume(move _2, const false) -> [return: bb3, unwind: bb4]; // scope 0 at $DIR/inline-generator.rs:9:14: 9:46
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-generator.rs:9:33: 9:39
--                                          // + literal: Const { ty: for<'r> fn(Pin<&'r mut [generator@$DIR/inline-generator.rs:15:5: 15:41]>, bool) -> GeneratorState<<[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::Yield, <[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::Return> {<[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::resume}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(Pin<&'r mut [generator@$DIR/inline-generator.rs:15:5: 15:41]>, bool) -> GeneratorState<<[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::Yield, <[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::Return> {<[generator@$DIR/inline-generator.rs:15:5: 15:41] as Generator<bool>>::resume}, val: Value(<ZST>) }
 +         StorageLive(_7);                 // scope 0 at $DIR/inline-generator.rs:9:14: 9:46
 +         _7 = const false;                // scope 0 at $DIR/inline-generator.rs:9:14: 9:46
 +         StorageLive(_10);                // scope 0 at $DIR/inline-generator.rs:9:14: 9:46
diff --git a/src/test/mir-opt/inline/inline_instruction_set.default.Inline.diff b/src/test/mir-opt/inline/inline_instruction_set.default.Inline.diff
index 65891cbb660e1..05bd99b62cd1f 100644
--- a/src/test/mir-opt/inline/inline_instruction_set.default.Inline.diff
+++ b/src/test/mir-opt/inline/inline_instruction_set.default.Inline.diff
@@ -14,7 +14,7 @@
           _1 = instruction_set_a32() -> bb1; // scope 0 at $DIR/inline-instruction-set.rs:51:5: 51:26
                                            // mir::Constant
                                            // + span: $DIR/inline-instruction-set.rs:51:5: 51:24
-                                           // + literal: Const { ty: fn() {instruction_set_a32}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {instruction_set_a32}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -23,7 +23,7 @@
           _2 = instruction_set_t32() -> bb2; // scope 0 at $DIR/inline-instruction-set.rs:52:5: 52:26
                                            // mir::Constant
                                            // + span: $DIR/inline-instruction-set.rs:52:5: 52:24
-                                           // + literal: Const { ty: fn() {instruction_set_t32}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {instruction_set_t32}, val: Value(<ZST>) }
       }
   
       bb2: {
@@ -32,7 +32,7 @@
 -         _3 = instruction_set_default() -> bb3; // scope 0 at $DIR/inline-instruction-set.rs:53:5: 53:30
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-instruction-set.rs:53:5: 53:28
--                                          // + literal: Const { ty: fn() {instruction_set_default}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() {instruction_set_default}, val: Value(<ZST>) }
 -     }
 - 
 -     bb3: {
diff --git a/src/test/mir-opt/inline/inline_instruction_set.t32.Inline.diff b/src/test/mir-opt/inline/inline_instruction_set.t32.Inline.diff
index 20e1d0ae4d5da..cb0d01428c946 100644
--- a/src/test/mir-opt/inline/inline_instruction_set.t32.Inline.diff
+++ b/src/test/mir-opt/inline/inline_instruction_set.t32.Inline.diff
@@ -14,7 +14,7 @@
           _1 = instruction_set_a32() -> bb1; // scope 0 at $DIR/inline-instruction-set.rs:42:5: 42:26
                                            // mir::Constant
                                            // + span: $DIR/inline-instruction-set.rs:42:5: 42:24
-                                           // + literal: Const { ty: fn() {instruction_set_a32}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {instruction_set_a32}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -23,7 +23,7 @@
 -         _2 = instruction_set_t32() -> bb2; // scope 0 at $DIR/inline-instruction-set.rs:43:5: 43:26
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-instruction-set.rs:43:5: 43:24
--                                          // + literal: Const { ty: fn() {instruction_set_t32}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() {instruction_set_t32}, val: Value(<ZST>) }
 -     }
 - 
 -     bb2: {
@@ -33,7 +33,7 @@
 +         _3 = instruction_set_default() -> bb2; // scope 0 at $DIR/inline-instruction-set.rs:46:5: 46:30
                                            // mir::Constant
                                            // + span: $DIR/inline-instruction-set.rs:46:5: 46:28
-                                           // + literal: Const { ty: fn() {instruction_set_default}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {instruction_set_default}, val: Value(<ZST>) }
       }
   
 -     bb3: {
diff --git a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
index 89414574898a6..17050f184cb48 100644
--- a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
+++ b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff
@@ -28,7 +28,7 @@
           _4 = alloc::alloc::exchange_malloc(move _2, move _3) -> bb1; // scope 2 at $DIR/inline-into-box-place.rs:8:29: 8:43
                                            // mir::Constant
                                            // + span: $DIR/inline-into-box-place.rs:8:29: 8:43
-                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -44,7 +44,7 @@
                                            // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:33: 8:41
 -                                          // + user_ty: UserType(1)
--                                          // + literal: Const { ty: fn() -> Vec<u32> {Vec::<u32>::new}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> Vec<u32> {Vec::<u32>::new}, val: Value(<ZST>) }
 -     }
 - 
 -     bb2: {
@@ -75,7 +75,7 @@
 -         _6 = alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>(move (_5.0: std::ptr::Unique<std::vec::Vec<u32>>), move (_5.1: std::alloc::Global)) -> bb5; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:42: 8:43
--                                          // + literal: Const { ty: unsafe fn(Unique<Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn(Unique<Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>}, val: Value(<ZST>) }
 -     }
 - 
 -     bb5 (cleanup): {
diff --git a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
index 89414574898a6..17050f184cb48 100644
--- a/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
+++ b/src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff
@@ -28,7 +28,7 @@
           _4 = alloc::alloc::exchange_malloc(move _2, move _3) -> bb1; // scope 2 at $DIR/inline-into-box-place.rs:8:29: 8:43
                                            // mir::Constant
                                            // + span: $DIR/inline-into-box-place.rs:8:29: 8:43
-                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -44,7 +44,7 @@
                                            // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:33: 8:41
 -                                          // + user_ty: UserType(1)
--                                          // + literal: Const { ty: fn() -> Vec<u32> {Vec::<u32>::new}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> Vec<u32> {Vec::<u32>::new}, val: Value(<ZST>) }
 -     }
 - 
 -     bb2: {
@@ -75,7 +75,7 @@
 -         _6 = alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>(move (_5.0: std::ptr::Unique<std::vec::Vec<u32>>), move (_5.1: std::alloc::Global)) -> bb5; // scope 0 at $DIR/inline-into-box-place.rs:8:42: 8:43
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-into-box-place.rs:8:42: 8:43
--                                          // + literal: Const { ty: unsafe fn(Unique<Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn(Unique<Vec<u32>>, std::alloc::Global) {alloc::alloc::box_free::<Vec<u32>, std::alloc::Global>}, val: Value(<ZST>) }
 -     }
 - 
 -     bb5 (cleanup): {
diff --git a/src/test/mir-opt/inline/inline_options.main.Inline.after.mir b/src/test/mir-opt/inline/inline_options.main.Inline.after.mir
index eca76df576bf6..45023083be668 100644
--- a/src/test/mir-opt/inline/inline_options.main.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_options.main.Inline.after.mir
@@ -15,7 +15,7 @@ fn main() -> () {
         _1 = not_inlined() -> bb1;       // scope 0 at $DIR/inline-options.rs:9:5: 9:18
                                          // mir::Constant
                                          // + span: $DIR/inline-options.rs:9:5: 9:16
-                                         // + literal: Const { ty: fn() {not_inlined}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {not_inlined}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -25,7 +25,7 @@ fn main() -> () {
         _3 = g() -> bb2;                 // scope 1 at $DIR/inline-options.rs:16:23: 16:26
                                          // mir::Constant
                                          // + span: $DIR/inline-options.rs:16:23: 16:24
-                                         // + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {g}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -34,7 +34,7 @@ fn main() -> () {
         _4 = g() -> bb3;                 // scope 1 at $DIR/inline-options.rs:16:28: 16:31
                                          // mir::Constant
                                          // + span: $DIR/inline-options.rs:16:28: 16:29
-                                         // + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {g}, val: Value(<ZST>) }
     }
 
     bb3: {
@@ -43,7 +43,7 @@ fn main() -> () {
         _5 = g() -> bb4;                 // scope 1 at $DIR/inline-options.rs:16:33: 16:36
                                          // mir::Constant
                                          // + span: $DIR/inline-options.rs:16:33: 16:34
-                                         // + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {g}, val: Value(<ZST>) }
     }
 
     bb4: {
diff --git a/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir b/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
index 2d85ff9a0cbc2..fcc1767578eb2 100644
--- a/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
@@ -27,7 +27,7 @@ fn bar() -> bool {
         _1 = foo;                        // scope 0 at $DIR/inline-retag.rs:11:13: 11:16
                                          // mir::Constant
                                          // + span: $DIR/inline-retag.rs:11:13: 11:16
-                                         // + literal: Const { ty: for<'r, 's> fn(&'r i32, &'s i32) -> bool {foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r, 's> fn(&'r i32, &'s i32) -> bool {foo}, val: Value(<ZST>) }
         StorageLive(_2);                 // scope 1 at $DIR/inline-retag.rs:12:5: 12:6
         _2 = _1;                         // scope 1 at $DIR/inline-retag.rs:12:5: 12:6
         StorageLive(_3);                 // scope 1 at $DIR/inline-retag.rs:12:7: 12:9
diff --git a/src/test/mir-opt/inline/inline_shims.clone.Inline.diff b/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
index 7170cd4057200..d67b07b0181b4 100644
--- a/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
+++ b/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
@@ -14,7 +14,7 @@
 -         _0 = <fn(A, B) as Clone>::clone(move _2) -> bb1; // scope 0 at $DIR/inline-shims.rs:6:5: 6:14
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-shims.rs:6:7: 6:12
--                                          // + literal: Const { ty: for<'r> fn(&'r fn(A, B)) -> fn(A, B) {<fn(A, B) as Clone>::clone}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r fn(A, B)) -> fn(A, B) {<fn(A, B) as Clone>::clone}, val: Value(<ZST>) }
 -     }
 - 
 -     bb1: {
diff --git a/src/test/mir-opt/inline/inline_shims.drop.Inline.diff b/src/test/mir-opt/inline/inline_shims.drop.Inline.diff
index aa55c90fcfb55..5c7cbc9b41900 100644
--- a/src/test/mir-opt/inline/inline_shims.drop.Inline.diff
+++ b/src/test/mir-opt/inline/inline_shims.drop.Inline.diff
@@ -24,7 +24,7 @@
           _3 = std::ptr::drop_in_place::<Vec<A>>(move _4) -> bb1; // scope 1 at $DIR/inline-shims.rs:11:14: 11:40
                                            // mir::Constant
                                            // + span: $DIR/inline-shims.rs:11:14: 11:37
-                                           // + literal: Const { ty: unsafe fn(*mut Vec<A>) {std::ptr::drop_in_place::<Vec<A>>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe fn(*mut Vec<A>) {std::ptr::drop_in_place::<Vec<A>>}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -35,7 +35,7 @@
 -         _0 = std::ptr::drop_in_place::<Option<B>>(move _5) -> bb2; // scope 2 at $DIR/inline-shims.rs:12:14: 12:40
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-shims.rs:12:14: 12:37
--                                          // + literal: Const { ty: unsafe fn(*mut Option<B>) {std::ptr::drop_in_place::<Option<B>>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe fn(*mut Option<B>) {std::ptr::drop_in_place::<Option<B>>}, val: Value(<ZST>) }
 +         StorageLive(_6);                 // scope 2 at $DIR/inline-shims.rs:12:14: 12:40
 +         StorageLive(_7);                 // scope 2 at $DIR/inline-shims.rs:12:14: 12:40
 +         _6 = discriminant((*_5));        // scope 3 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
diff --git a/src/test/mir-opt/inline/inline_specialization.main.Inline.diff b/src/test/mir-opt/inline/inline_specialization.main.Inline.diff
index 8e93baf6a7050..747eeb9845073 100644
--- a/src/test/mir-opt/inline/inline_specialization.main.Inline.diff
+++ b/src/test/mir-opt/inline/inline_specialization.main.Inline.diff
@@ -15,7 +15,7 @@
 -         _1 = <Vec<()> as Foo>::bar() -> bb1; // scope 0 at $DIR/inline-specialization.rs:5:13: 5:38
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-specialization.rs:5:13: 5:36
--                                          // + literal: Const { ty: fn() -> u32 {<Vec<()> as Foo>::bar}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: fn() -> u32 {<Vec<()> as Foo>::bar}, val: Value(<ZST>) }
 -     }
 - 
 -     bb1: {
diff --git a/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir b/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
index 0be979901ac03..1646de9289a81 100644
--- a/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
@@ -11,7 +11,7 @@ fn test(_1: &dyn X) -> u32 {
         _0 = <dyn X as X>::y(move _2) -> bb1; // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:10
                                          // mir::Constant
                                          // + span: $DIR/inline-trait-method.rs:9:7: 9:8
-                                         // + literal: Const { ty: for<'r> fn(&'r dyn X) -> u32 {<dyn X as X>::y}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r dyn X) -> u32 {<dyn X as X>::y}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/inline/inline_trait_method_2.test2.Inline.after.mir b/src/test/mir-opt/inline/inline_trait_method_2.test2.Inline.after.mir
index 64375b6edc93e..eb6c09c1cd798 100644
--- a/src/test/mir-opt/inline/inline_trait_method_2.test2.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_trait_method_2.test2.Inline.after.mir
@@ -21,7 +21,7 @@ fn test2(_1: &dyn X) -> bool {
         _0 = <dyn X as X>::y(move _4) -> bb1; // scope 1 at $DIR/inline-trait-method_2.rs:10:5: 10:10
                                          // mir::Constant
                                          // + span: $DIR/inline-trait-method_2.rs:10:7: 10:8
-                                         // + literal: Const { ty: for<'r> fn(&'r dyn X) -> bool {<dyn X as X>::y}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r dyn X) -> bool {<dyn X as X>::y}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/inline/issue_78442.bar.Inline.diff b/src/test/mir-opt/inline/issue_78442.bar.Inline.diff
index b44f9900d6c6a..f91d352622626 100644
--- a/src/test/mir-opt/inline/issue_78442.bar.Inline.diff
+++ b/src/test/mir-opt/inline/issue_78442.bar.Inline.diff
@@ -19,7 +19,7 @@
 +         _4 = hide_foo() -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/issue-78442.rs:11:5: 11:15
                                            // mir::Constant
                                            // + span: $DIR/issue-78442.rs:11:5: 11:13
-                                           // + literal: Const { ty: fn() -> impl Fn() {hide_foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> impl Fn() {hide_foo}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -29,7 +29,7 @@
 -         _2 = <fn() {foo} as Fn<()>>::call(move _3, move _5) -> [return: bb2, unwind: bb4]; // scope 0 at $DIR/issue-78442.rs:11:5: 11:17
 -                                          // mir::Constant
 -                                          // + span: $DIR/issue-78442.rs:11:5: 11:15
--                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r fn() {foo}, ()) -> <fn() {foo} as FnOnce<()>>::Output {<fn() {foo} as Fn<()>>::call}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r fn() {foo}, ()) -> <fn() {foo} as FnOnce<()>>::Output {<fn() {foo} as Fn<()>>::call}, val: Value(<ZST>) }
 +         _2 = move (*_3)() -> [return: bb5, unwind: bb3]; // scope 1 at $SRC_DIR/core/src/ops/function.rs:LL:COL
       }
   
diff --git a/src/test/mir-opt/inline/issue_78442.bar.RevealAll.diff b/src/test/mir-opt/inline/issue_78442.bar.RevealAll.diff
index 8a998fb50006c..4446280e72004 100644
--- a/src/test/mir-opt/inline/issue_78442.bar.RevealAll.diff
+++ b/src/test/mir-opt/inline/issue_78442.bar.RevealAll.diff
@@ -18,7 +18,7 @@
           _4 = hide_foo() -> [return: bb1, unwind: bb4]; // scope 0 at $DIR/issue-78442.rs:11:5: 11:15
                                            // mir::Constant
                                            // + span: $DIR/issue-78442.rs:11:5: 11:13
-                                           // + literal: Const { ty: fn() -> impl Fn() {hide_foo}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> impl Fn() {hide_foo}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -29,8 +29,8 @@
 +         _2 = <fn() {foo} as Fn<()>>::call(move _3, move _5) -> [return: bb2, unwind: bb4]; // scope 0 at $DIR/issue-78442.rs:11:5: 11:17
                                            // mir::Constant
                                            // + span: $DIR/issue-78442.rs:11:5: 11:15
--                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(Scalar(<ZST>)) }
-+                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r fn() {foo}, ()) -> <fn() {foo} as FnOnce<()>>::Output {<fn() {foo} as Fn<()>>::call}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(<ZST>) }
++                                          // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r fn() {foo}, ()) -> <fn() {foo} as FnOnce<()>>::Output {<fn() {foo} as Fn<()>>::call}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/issue_41110.main.ElaborateDrops.after.mir b/src/test/mir-opt/issue_41110.main.ElaborateDrops.after.mir
index 7113c42b9c77f..19110894dc720 100644
--- a/src/test/mir-opt/issue_41110.main.ElaborateDrops.after.mir
+++ b/src/test/mir-opt/issue_41110.main.ElaborateDrops.after.mir
@@ -23,7 +23,7 @@ fn main() -> () {
         _3 = S::id(move _4) -> [return: bb1, unwind: bb4]; // scope 0 at $DIR/issue-41110.rs:8:21: 8:27
                                          // mir::Constant
                                          // + span: $DIR/issue-41110.rs:8:23: 8:25
-                                         // + literal: Const { ty: fn(S) -> S {S::id}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(S) -> S {S::id}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -32,7 +32,7 @@ fn main() -> () {
         _1 = S::other(move _2, move _3) -> [return: bb2, unwind: bb3]; // scope 0 at $DIR/issue-41110.rs:8:13: 8:28
                                          // mir::Constant
                                          // + span: $DIR/issue-41110.rs:8:15: 8:20
-                                         // + literal: Const { ty: fn(S, S) {S::other}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(S, S) {S::other}, val: Value(<ZST>) }
     }
 
     bb2: {
diff --git a/src/test/mir-opt/issue_41110.test.ElaborateDrops.after.mir b/src/test/mir-opt/issue_41110.test.ElaborateDrops.after.mir
index c4e852ca3212a..1901ea1747ed2 100644
--- a/src/test/mir-opt/issue_41110.test.ElaborateDrops.after.mir
+++ b/src/test/mir-opt/issue_41110.test.ElaborateDrops.after.mir
@@ -28,7 +28,7 @@ fn test() -> () {
         _3 = std::mem::drop::<S>(move _4) -> [return: bb1, unwind: bb7]; // scope 2 at $DIR/issue-41110.rs:17:5: 17:12
                                          // mir::Constant
                                          // + span: $DIR/issue-41110.rs:17:5: 17:9
-                                         // + literal: Const { ty: fn(S) {std::mem::drop::<S>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(S) {std::mem::drop::<S>}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/issue_41888.main.ElaborateDrops.after.mir b/src/test/mir-opt/issue_41888.main.ElaborateDrops.after.mir
index ce7ca20358e12..a4ff718f42258 100644
--- a/src/test/mir-opt/issue_41888.main.ElaborateDrops.after.mir
+++ b/src/test/mir-opt/issue_41888.main.ElaborateDrops.after.mir
@@ -29,7 +29,7 @@ fn main() -> () {
         _2 = cond() -> [return: bb1, unwind: bb11]; // scope 1 at $DIR/issue-41888.rs:8:8: 8:14
                                          // mir::Constant
                                          // + span: $DIR/issue-41888.rs:8:8: 8:12
-                                         // + literal: Const { ty: fn() -> bool {cond}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> bool {cond}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/issue_49232.main.mir_map.0.mir b/src/test/mir-opt/issue_49232.main.mir_map.0.mir
index 2f8931382a69e..6301763449b90 100644
--- a/src/test/mir-opt/issue_49232.main.mir_map.0.mir
+++ b/src/test/mir-opt/issue_49232.main.mir_map.0.mir
@@ -59,7 +59,7 @@ fn main() -> () {
         _5 = std::mem::drop::<&i32>(move _6) -> [return: bb9, unwind: bb11]; // scope 1 at $DIR/issue-49232.rs:13:9: 13:22
                                          // mir::Constant
                                          // + span: $DIR/issue-49232.rs:13:9: 13:13
-                                         // + literal: Const { ty: fn(&i32) {std::mem::drop::<&i32>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(&i32) {std::mem::drop::<&i32>}, val: Value(<ZST>) }
     }
 
     bb9: {
diff --git a/src/test/mir-opt/issue_62289.test.ElaborateDrops.before.mir b/src/test/mir-opt/issue_62289.test.ElaborateDrops.before.mir
index 4d06b91e6dc61..f21e9bbd270a2 100644
--- a/src/test/mir-opt/issue_62289.test.ElaborateDrops.before.mir
+++ b/src/test/mir-opt/issue_62289.test.ElaborateDrops.before.mir
@@ -34,7 +34,7 @@ fn test() -> Option<Box<u32>> {
         _4 = alloc::alloc::exchange_malloc(move _2, move _3) -> bb1; // scope 1 at $DIR/issue-62289.rs:9:10: 9:21
                                          // mir::Constant
                                          // + span: $DIR/issue-62289.rs:9:10: 9:21
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -46,7 +46,7 @@ fn test() -> Option<Box<u32>> {
         _6 = <Option<u32> as Try>::branch(move _7) -> [return: bb2, unwind: bb12]; // scope 0 at $DIR/issue-62289.rs:9:15: 9:20
                                          // mir::Constant
                                          // + span: $DIR/issue-62289.rs:9:15: 9:20
-                                         // + literal: Const { ty: fn(Option<u32>) -> ControlFlow<<Option<u32> as Try>::Residual, <Option<u32> as Try>::Output> {<Option<u32> as Try>::branch}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Option<u32>) -> ControlFlow<<Option<u32> as Try>::Residual, <Option<u32> as Try>::Output> {<Option<u32> as Try>::branch}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -76,7 +76,7 @@ fn test() -> Option<Box<u32>> {
         _0 = <Option<Box<u32>> as FromResidual<Option<Infallible>>>::from_residual(move _11) -> [return: bb6, unwind: bb12]; // scope 3 at $DIR/issue-62289.rs:9:15: 9:20
                                          // mir::Constant
                                          // + span: $DIR/issue-62289.rs:9:19: 9:20
-                                         // + literal: Const { ty: fn(Option<Infallible>) -> Option<Box<u32>> {<Option<Box<u32>> as FromResidual<Option<Infallible>>>::from_residual}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Option<Infallible>) -> Option<Box<u32>> {<Option<Box<u32>> as FromResidual<Option<Infallible>>>::from_residual}, val: Value(<ZST>) }
     }
 
     bb6: {
diff --git a/src/test/mir-opt/issue_72181.main.mir_map.0.32bit.mir b/src/test/mir-opt/issue_72181.main.mir_map.0.32bit.mir
index 2e6783b7f3c9d..f4602d147c947 100644
--- a/src/test/mir-opt/issue_72181.main.mir_map.0.32bit.mir
+++ b/src/test/mir-opt/issue_72181.main.mir_map.0.32bit.mir
@@ -25,7 +25,7 @@ fn main() -> () {
         _1 = std::mem::size_of::<Foo>() -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
                                          // mir::Constant
                                          // + span: $DIR/issue-72181.rs:24:13: 24:32
-                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/issue_72181.main.mir_map.0.64bit.mir b/src/test/mir-opt/issue_72181.main.mir_map.0.64bit.mir
index 2e6783b7f3c9d..f4602d147c947 100644
--- a/src/test/mir-opt/issue_72181.main.mir_map.0.64bit.mir
+++ b/src/test/mir-opt/issue_72181.main.mir_map.0.64bit.mir
@@ -25,7 +25,7 @@ fn main() -> () {
         _1 = std::mem::size_of::<Foo>() -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
                                          // mir::Constant
                                          // + span: $DIR/issue-72181.rs:24:13: 24:32
-                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir b/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
index 899c84687890b..9842e26ab6993 100644
--- a/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
+++ b/src/test/mir-opt/issue_72181_1.main.mir_map.0.mir
@@ -24,7 +24,7 @@ fn main() -> () {
         _2 = transmute::<(), Void>(move _3) -> bb4; // scope 2 at $DIR/issue-72181-1.rs:17:9: 17:44
                                          // mir::Constant
                                          // + span: $DIR/issue-72181-1.rs:17:9: 17:40
-                                         // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(()) -> Void {transmute::<(), Void>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(()) -> Void {transmute::<(), Void>}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -37,7 +37,7 @@ fn main() -> () {
         _4 = f(move _5) -> bb4;          // scope 1 at $DIR/issue-72181-1.rs:20:5: 20:9
                                          // mir::Constant
                                          // + span: $DIR/issue-72181-1.rs:20:5: 20:6
-                                         // + literal: Const { ty: fn(Void) -> ! {f}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(Void) -> ! {f}, val: Value(<ZST>) }
     }
 
     bb2: {
diff --git a/src/test/mir-opt/issue_73223.main.PreCodegen.32bit.diff b/src/test/mir-opt/issue_73223.main.PreCodegen.32bit.diff
index 8b0a73ec4ba61..9295265154424 100644
--- a/src/test/mir-opt/issue_73223.main.PreCodegen.32bit.diff
+++ b/src/test/mir-opt/issue_73223.main.PreCodegen.32bit.diff
@@ -98,7 +98,7 @@
           _14 = core::panicking::assert_failed::<i32, i32>(const core::panicking::AssertKind::Eq, move _15, move _17, move _19); // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // + literal: Const { ty: core::panicking::AssertKind, val: Value(Scalar(0x00)) }
diff --git a/src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff b/src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff
index 8b0a73ec4ba61..9295265154424 100644
--- a/src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff
+++ b/src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff
@@ -98,7 +98,7 @@
           _14 = core::panicking::assert_failed::<i32, i32>(const core::panicking::AssertKind::Eq, move _15, move _17, move _19); // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // + literal: Const { ty: core::panicking::AssertKind, val: Value(Scalar(0x00)) }
diff --git a/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff b/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff
index c96a6641bab91..f52b1a953c120 100644
--- a/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff
+++ b/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff
@@ -135,7 +135,7 @@
           _21 = core::panicking::assert_failed::<i32, i32>(const core::panicking::AssertKind::Eq, move _23, move _25, move _27); // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // + literal: Const { ty: core::panicking::AssertKind, val: Value(Scalar(0x00)) }
diff --git a/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff b/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff
index c96a6641bab91..f52b1a953c120 100644
--- a/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff
+++ b/src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff
@@ -135,7 +135,7 @@
           _21 = core::panicking::assert_failed::<i32, i32>(const core::panicking::AssertKind::Eq, move _23, move _25, move _27); // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r i32, &'s i32, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<i32, i32>}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // + literal: Const { ty: core::panicking::AssertKind, val: Value(Scalar(0x00)) }
diff --git a/src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff b/src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff
index 29bcef26518a1..14bb66910fe3c 100644
--- a/src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff
+++ b/src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff
@@ -70,7 +70,7 @@
           _22 = core::panicking::panic(const "internal error: entered unreachable code"); // scope 1 at $SRC_DIR/core/src/panic.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/panic.rs:LL:COL
-                                           // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(<ZST>) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/panic.rs:LL:COL
                                            // + literal: Const { ty: &str, val: Value(Slice(..)) }
diff --git a/src/test/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.mir b/src/test/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.mir
index 40e7b74453a7c..dd85434d879c3 100644
--- a/src/test/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.mir
+++ b/src/test/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.mir
@@ -39,7 +39,7 @@ fn num_to_digit(_1: char) -> u32 {
         _7 = char::methods::<impl char>::to_digit(move _8, const 8_u32) -> bb5; // scope 1 at $SRC_DIR/core/src/char/methods.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/char/methods.rs:LL:COL
-                                         // + literal: Const { ty: fn(char, u32) -> Option<u32> {char::methods::<impl char>::to_digit}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(char, u32) -> Option<u32> {char::methods::<impl char>::to_digit}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -50,7 +50,7 @@ fn num_to_digit(_1: char) -> u32 {
         _3 = char::methods::<impl char>::to_digit(move _4, const 8_u32) -> bb2; // scope 0 at $DIR/issue-59352.rs:14:26: 14:41
                                          // mir::Constant
                                          // + span: $DIR/issue-59352.rs:14:30: 14:38
-                                         // + literal: Const { ty: fn(char, u32) -> Option<u32> {char::methods::<impl char>::to_digit}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(char, u32) -> Option<u32> {char::methods::<impl char>::to_digit}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -90,7 +90,7 @@ fn num_to_digit(_1: char) -> u32 {
         _11 = core::panicking::panic(const "called `Option::unwrap()` on a `None` value"); // scope 3 at $SRC_DIR/core/src/option.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/option.rs:LL:COL
-                                         // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(<ZST>) }
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/option.rs:LL:COL
                                          // + literal: Const { ty: &str, val: Value(Slice(..)) }
diff --git a/src/test/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff b/src/test/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff
index b8023a6a8e690..08ff3b67655ce 100644
--- a/src/test/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff
+++ b/src/test/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff
@@ -27,7 +27,7 @@
           _2 = transmute::<[u8; 16], [u32; 4]>(move _3) -> bb1; // scope 2 at $DIR/issue-75439.rs:7:37: 7:53
                                            // mir::Constant
                                            // + span: $DIR/issue-75439.rs:7:37: 7:46
-                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn([u8; 16]) -> [u32; 4] {transmute::<[u8; 16], [u32; 4]>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn([u8; 16]) -> [u32; 4] {transmute::<[u8; 16], [u32; 4]>}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -50,7 +50,7 @@
           _5 = transmute::<u32, [u8; 4]>(move _6) -> bb7; // scope 4 at $DIR/issue-75439.rs:10:23: 10:36
                                            // mir::Constant
                                            // + span: $DIR/issue-75439.rs:10:23: 10:32
-                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(u32) -> [u8; 4] {transmute::<u32, [u8; 4]>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(u32) -> [u8; 4] {transmute::<u32, [u8; 4]>}, val: Value(<ZST>) }
       }
   
       bb5: {
diff --git a/src/test/mir-opt/lower_intrinsics.align_of.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.align_of.LowerIntrinsics.diff
index 3f5f71f80825d..1b9e46c6a6d0a 100644
--- a/src/test/mir-opt/lower_intrinsics.align_of.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.align_of.LowerIntrinsics.diff
@@ -8,7 +8,7 @@
 -         _0 = std::intrinsics::min_align_of::<T>() -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:19:5: 19:42
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:19:5: 19:40
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::min_align_of::<T>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::min_align_of::<T>}, val: Value(<ZST>) }
 +         _0 = AlignOf(T);                 // scope 0 at $DIR/lower_intrinsics.rs:19:5: 19:42
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:19:5: 19:42
       }
diff --git a/src/test/mir-opt/lower_intrinsics.discriminant.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.discriminant.LowerIntrinsics.diff
index 88d2867fc42ab..9bda88ce2c7e8 100644
--- a/src/test/mir-opt/lower_intrinsics.discriminant.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.discriminant.LowerIntrinsics.diff
@@ -32,7 +32,7 @@
 -         _2 = discriminant_value::<T>(move _3) -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:74:5: 74:45
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:74:5: 74:41
--                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r T) -> <T as DiscriminantKind>::Discriminant {discriminant_value::<T>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r T) -> <T as DiscriminantKind>::Discriminant {discriminant_value::<T>}, val: Value(<ZST>) }
 +         _2 = discriminant((*_3));        // scope 0 at $DIR/lower_intrinsics.rs:74:5: 74:45
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:74:5: 74:45
       }
@@ -53,7 +53,7 @@
 -         _5 = discriminant_value::<i32>(move _6) -> bb2; // scope 0 at $DIR/lower_intrinsics.rs:75:5: 75:45
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:75:5: 75:41
--                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r i32) -> <i32 as DiscriminantKind>::Discriminant {discriminant_value::<i32>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r i32) -> <i32 as DiscriminantKind>::Discriminant {discriminant_value::<i32>}, val: Value(<ZST>) }
 +         _5 = discriminant((*_6));        // scope 0 at $DIR/lower_intrinsics.rs:75:5: 75:45
 +         goto -> bb2;                     // scope 0 at $DIR/lower_intrinsics.rs:75:5: 75:45
       }
@@ -74,7 +74,7 @@
 -         _9 = discriminant_value::<()>(move _10) -> bb3; // scope 0 at $DIR/lower_intrinsics.rs:76:5: 76:46
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:76:5: 76:41
--                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r ()) -> <() as DiscriminantKind>::Discriminant {discriminant_value::<()>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r ()) -> <() as DiscriminantKind>::Discriminant {discriminant_value::<()>}, val: Value(<ZST>) }
 +         _9 = discriminant((*_10));       // scope 0 at $DIR/lower_intrinsics.rs:76:5: 76:46
 +         goto -> bb3;                     // scope 0 at $DIR/lower_intrinsics.rs:76:5: 76:46
       }
@@ -95,7 +95,7 @@
 -         _13 = discriminant_value::<E>(move _14) -> bb4; // scope 0 at $DIR/lower_intrinsics.rs:77:5: 77:48
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:77:5: 77:41
--                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r E) -> <E as DiscriminantKind>::Discriminant {discriminant_value::<E>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> extern "rust-intrinsic" fn(&'r E) -> <E as DiscriminantKind>::Discriminant {discriminant_value::<E>}, val: Value(<ZST>) }
 +         _13 = discriminant((*_14));      // scope 0 at $DIR/lower_intrinsics.rs:77:5: 77:48
 +         goto -> bb4;                     // scope 0 at $DIR/lower_intrinsics.rs:77:5: 77:48
       }
diff --git a/src/test/mir-opt/lower_intrinsics.f_u64.PreCodegen.before.mir b/src/test/mir-opt/lower_intrinsics.f_u64.PreCodegen.before.mir
index 7750624db30fb..a12aa1d6686a9 100644
--- a/src/test/mir-opt/lower_intrinsics.f_u64.PreCodegen.before.mir
+++ b/src/test/mir-opt/lower_intrinsics.f_u64.PreCodegen.before.mir
@@ -20,7 +20,7 @@ fn f_u64() -> () {
         _2 = f_non_zst::<u64>(move _3) -> bb1; // scope 1 at $DIR/lower_intrinsics.rs:48:9: 48:21
                                          // mir::Constant
                                          // + span: $DIR/lower_intrinsics.rs:48:9: 48:18
-                                         // + literal: Const { ty: fn(u64) {f_non_zst::<u64>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(u64) {f_non_zst::<u64>}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/lower_intrinsics.f_unit.PreCodegen.before.mir b/src/test/mir-opt/lower_intrinsics.f_unit.PreCodegen.before.mir
index 4d4e65d311416..49e3b9144a59a 100644
--- a/src/test/mir-opt/lower_intrinsics.f_unit.PreCodegen.before.mir
+++ b/src/test/mir-opt/lower_intrinsics.f_unit.PreCodegen.before.mir
@@ -6,6 +6,7 @@ fn f_unit() -> () {
     scope 1 (inlined f_dispatch::<()>) { // at $DIR/lower_intrinsics.rs:34:5: 34:19
         debug t => _1;                   // in scope 1 at $DIR/lower_intrinsics.rs:44:22: 44:23
         let _2: ();                      // in scope 1 at $DIR/lower_intrinsics.rs:46:9: 46:17
+        let mut _3: ();                  // in scope 1 at $DIR/lower_intrinsics.rs:46:15: 46:16
         scope 2 (inlined std::mem::size_of::<()>) { // at $DIR/lower_intrinsics.rs:45:8: 45:32
         }
     }
@@ -13,13 +14,15 @@ fn f_unit() -> () {
     bb0: {
         StorageLive(_1);                 // scope 0 at $DIR/lower_intrinsics.rs:34:16: 34:18
         StorageLive(_2);                 // scope 1 at $DIR/lower_intrinsics.rs:46:9: 46:17
-        _2 = f_zst::<()>(const ()) -> bb1; // scope 1 at $DIR/lower_intrinsics.rs:46:9: 46:17
+        StorageLive(_3);                 // scope 1 at $DIR/lower_intrinsics.rs:46:15: 46:16
+        _2 = f_zst::<()>(move _3) -> bb1; // scope 1 at $DIR/lower_intrinsics.rs:46:9: 46:17
                                          // mir::Constant
                                          // + span: $DIR/lower_intrinsics.rs:46:9: 46:14
-                                         // + literal: Const { ty: fn(()) {f_zst::<()>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(()) {f_zst::<()>}, val: Value(<ZST>) }
     }
 
     bb1: {
+        StorageDead(_3);                 // scope 1 at $DIR/lower_intrinsics.rs:46:16: 46:17
         StorageDead(_2);                 // scope 1 at $DIR/lower_intrinsics.rs:46:17: 46:18
         StorageDead(_1);                 // scope 0 at $DIR/lower_intrinsics.rs:34:18: 34:19
         return;                          // scope 0 at $DIR/lower_intrinsics.rs:35:2: 35:2
diff --git a/src/test/mir-opt/lower_intrinsics.forget.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.forget.LowerIntrinsics.diff
index 7e1e066366c11..6c99e1b7ca6cb 100644
--- a/src/test/mir-opt/lower_intrinsics.forget.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.forget.LowerIntrinsics.diff
@@ -12,7 +12,7 @@
 -         _0 = std::intrinsics::forget::<T>(move _2) -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:24:5: 24:32
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:24:5: 24:29
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn(T) {std::intrinsics::forget::<T>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn(T) {std::intrinsics::forget::<T>}, val: Value(<ZST>) }
 +         _0 = const ();                   // scope 0 at $DIR/lower_intrinsics.rs:24:5: 24:32
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:24:5: 24:32
       }
diff --git a/src/test/mir-opt/lower_intrinsics.non_const.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.non_const.LowerIntrinsics.diff
index 276227d8c018a..41dac17dcb640 100644
--- a/src/test/mir-opt/lower_intrinsics.non_const.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.non_const.LowerIntrinsics.diff
@@ -14,7 +14,7 @@
           _1 = std::intrinsics::size_of::<T>; // scope 0 at $DIR/lower_intrinsics.rs:62:21: 62:51
                                            // mir::Constant
                                            // + span: $DIR/lower_intrinsics.rs:62:21: 62:51
-                                           // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::size_of::<T>}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::size_of::<T>}, val: Value(<ZST>) }
           StorageLive(_2);                 // scope 1 at $DIR/lower_intrinsics.rs:63:5: 63:14
           _2 = _1;                         // scope 1 at $DIR/lower_intrinsics.rs:63:5: 63:14
 -         _0 = move _2() -> bb1;           // scope 1 at $DIR/lower_intrinsics.rs:63:5: 63:16
diff --git a/src/test/mir-opt/lower_intrinsics.size_of.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.size_of.LowerIntrinsics.diff
index b5a77702a8ef0..cd6da6f1dc745 100644
--- a/src/test/mir-opt/lower_intrinsics.size_of.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.size_of.LowerIntrinsics.diff
@@ -8,7 +8,7 @@
 -         _0 = std::intrinsics::size_of::<T>() -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:14:5: 14:37
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:14:5: 14:35
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::size_of::<T>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn() -> usize {std::intrinsics::size_of::<T>}, val: Value(<ZST>) }
 +         _0 = SizeOf(T);                  // scope 0 at $DIR/lower_intrinsics.rs:14:5: 14:37
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:14:5: 14:37
       }
diff --git a/src/test/mir-opt/lower_intrinsics.unreachable.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.unreachable.LowerIntrinsics.diff
index eb463afbf7795..0ce8d85070c70 100644
--- a/src/test/mir-opt/lower_intrinsics.unreachable.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.unreachable.LowerIntrinsics.diff
@@ -15,7 +15,7 @@
 -         _3 = std::intrinsics::unreachable(); // scope 1 at $DIR/lower_intrinsics.rs:29:14: 29:45
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:29:14: 29:43
--                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn() -> ! {std::intrinsics::unreachable}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: unsafe extern "rust-intrinsic" fn() -> ! {std::intrinsics::unreachable}, val: Value(<ZST>) }
 +         unreachable;                     // scope 1 at $DIR/lower_intrinsics.rs:29:14: 29:45
       }
   
diff --git a/src/test/mir-opt/lower_intrinsics.wrapping.LowerIntrinsics.diff b/src/test/mir-opt/lower_intrinsics.wrapping.LowerIntrinsics.diff
index 5a0286bad2fb7..ebe240121cc5f 100644
--- a/src/test/mir-opt/lower_intrinsics.wrapping.LowerIntrinsics.diff
+++ b/src/test/mir-opt/lower_intrinsics.wrapping.LowerIntrinsics.diff
@@ -33,7 +33,7 @@
 -         _3 = wrapping_add::<i32>(move _4, move _5) -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:7:14: 7:50
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:7:14: 7:44
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_add::<i32>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_add::<i32>}, val: Value(<ZST>) }
 +         _3 = Add(move _4, move _5);      // scope 0 at $DIR/lower_intrinsics.rs:7:14: 7:50
 +         goto -> bb1;                     // scope 0 at $DIR/lower_intrinsics.rs:7:14: 7:50
       }
@@ -49,7 +49,7 @@
 -         _6 = wrapping_sub::<i32>(move _7, move _8) -> bb2; // scope 1 at $DIR/lower_intrinsics.rs:8:14: 8:50
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:8:14: 8:44
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_sub::<i32>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_sub::<i32>}, val: Value(<ZST>) }
 +         _6 = Sub(move _7, move _8);      // scope 1 at $DIR/lower_intrinsics.rs:8:14: 8:50
 +         goto -> bb2;                     // scope 1 at $DIR/lower_intrinsics.rs:8:14: 8:50
       }
@@ -65,7 +65,7 @@
 -         _9 = wrapping_mul::<i32>(move _10, move _11) -> bb3; // scope 2 at $DIR/lower_intrinsics.rs:9:14: 9:50
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_intrinsics.rs:9:14: 9:44
--                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_mul::<i32>}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: extern "rust-intrinsic" fn(i32, i32) -> i32 {wrapping_mul::<i32>}, val: Value(<ZST>) }
 +         _9 = Mul(move _10, move _11);    // scope 2 at $DIR/lower_intrinsics.rs:9:14: 9:50
 +         goto -> bb3;                     // scope 2 at $DIR/lower_intrinsics.rs:9:14: 9:50
       }
diff --git a/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
index 13241d882f210..96404f0506cf2 100644
--- a/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
+++ b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
@@ -23,7 +23,7 @@
 -         _5 = core::slice::<impl [u8]>::len(move _6) -> bb1; // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_slice_len.rs:5:22: 5:25
--                                          // + literal: Const { ty: for<'r> fn(&'r [u8]) -> usize {core::slice::<impl [u8]>::len}, val: Value(Scalar(<ZST>)) }
+-                                          // + literal: Const { ty: for<'r> fn(&'r [u8]) -> usize {core::slice::<impl [u8]>::len}, val: Value(<ZST>) }
 +         _5 = Len((*_6));                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
 +         goto -> bb1;                     // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
       }
diff --git a/src/test/mir-opt/match_false_edges.full_tested_match.PromoteTemps.after.mir b/src/test/mir-opt/match_false_edges.full_tested_match.PromoteTemps.after.mir
index 0d0204e126a6c..722097630f79b 100644
--- a/src/test/mir-opt/match_false_edges.full_tested_match.PromoteTemps.after.mir
+++ b/src/test/mir-opt/match_false_edges.full_tested_match.PromoteTemps.after.mir
@@ -61,7 +61,7 @@ fn full_tested_match() -> () {
         _7 = guard() -> [return: bb6, unwind: bb11]; // scope 0 at $DIR/match_false_edges.rs:14:20: 14:27
                                          // mir::Constant
                                          // + span: $DIR/match_false_edges.rs:14:20: 14:25
-                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(<ZST>) }
     }
 
     bb6: {
diff --git a/src/test/mir-opt/match_false_edges.full_tested_match2.PromoteTemps.before.mir b/src/test/mir-opt/match_false_edges.full_tested_match2.PromoteTemps.before.mir
index 270cc85ce032a..df052e32157db 100644
--- a/src/test/mir-opt/match_false_edges.full_tested_match2.PromoteTemps.before.mir
+++ b/src/test/mir-opt/match_false_edges.full_tested_match2.PromoteTemps.before.mir
@@ -62,7 +62,7 @@ fn full_tested_match2() -> () {
         _7 = guard() -> [return: bb6, unwind: bb11]; // scope 0 at $DIR/match_false_edges.rs:25:20: 25:27
                                          // mir::Constant
                                          // + span: $DIR/match_false_edges.rs:25:20: 25:25
-                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(<ZST>) }
     }
 
     bb6: {
diff --git a/src/test/mir-opt/match_false_edges.main.PromoteTemps.before.mir b/src/test/mir-opt/match_false_edges.main.PromoteTemps.before.mir
index 2f76e0137bd69..fc50db397fdcf 100644
--- a/src/test/mir-opt/match_false_edges.main.PromoteTemps.before.mir
+++ b/src/test/mir-opt/match_false_edges.main.PromoteTemps.before.mir
@@ -70,7 +70,7 @@ fn main() -> () {
         _8 = guard() -> [return: bb6, unwind: bb15]; // scope 0 at $DIR/match_false_edges.rs:34:21: 34:28
                                          // mir::Constant
                                          // + span: $DIR/match_false_edges.rs:34:21: 34:26
-                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> bool {guard}, val: Value(<ZST>) }
     }
 
     bb6: {
@@ -113,7 +113,7 @@ fn main() -> () {
         _12 = guard2(move _13) -> [return: bb11, unwind: bb15]; // scope 0 at $DIR/match_false_edges.rs:36:20: 36:29
                                          // mir::Constant
                                          // + span: $DIR/match_false_edges.rs:36:20: 36:26
-                                         // + literal: Const { ty: fn(i32) -> bool {guard2}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(i32) -> bool {guard2}, val: Value(<ZST>) }
     }
 
     bb11: {
diff --git a/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.32bit.mir b/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.32bit.mir
index 7d9e012bb296e..e1d870ef9a4e9 100644
--- a/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.32bit.mir
+++ b/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.32bit.mir
@@ -70,30 +70,30 @@ fn main() -> () {
         StorageLive(_8);                 // bb2[0]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
         StorageLive(_9);                 // bb2[1]: scope 3 at $DIR/region-subtyping-basic.rs:21:15: 21:17
         _9 = (*_6);                      // bb2[2]: scope 3 at $DIR/region-subtyping-basic.rs:21:15: 21:17
-        _8 = ConstValue(Scalar(<ZST>): fn(usize) -> bool {use_x})(move _9) -> [return: bb3, unwind: bb7]; // bb2[3]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
+        _8 = ConstValue(ZeroSized: fn(usize) -> bool {use_x})(move _9) -> [return: bb3, unwind: bb7]; // bb2[3]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
                                          // mir::Constant
                                          // + span: $DIR/region-subtyping-basic.rs:21:9: 21:14
-                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(<ZST>) }
     }
 
     bb3: {
         StorageDead(_9);                 // bb3[0]: scope 3 at $DIR/region-subtyping-basic.rs:21:17: 21:18
         StorageDead(_8);                 // bb3[1]: scope 3 at $DIR/region-subtyping-basic.rs:21:18: 21:19
-        _0 = const ConstValue(Scalar(<ZST>): ()); // bb3[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:13: 22:6
+        _0 = const ConstValue(ZeroSized: ()); // bb3[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:13: 22:6
         goto -> bb6;                     // bb3[3]: scope 3 at $DIR/region-subtyping-basic.rs:20:5: 24:6
     }
 
     bb4: {
         StorageLive(_10);                // bb4[0]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
-        _10 = ConstValue(Scalar(<ZST>): fn(usize) -> bool {use_x})(const ConstValue(Scalar(0x00000016): usize)) -> [return: bb5, unwind: bb7]; // bb4[1]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
+        _10 = ConstValue(ZeroSized: fn(usize) -> bool {use_x})(const ConstValue(Scalar(0x00000016): usize)) -> [return: bb5, unwind: bb7]; // bb4[1]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
                                          // mir::Constant
                                          // + span: $DIR/region-subtyping-basic.rs:23:9: 23:14
-                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(<ZST>) }
     }
 
     bb5: {
         StorageDead(_10);                // bb5[0]: scope 3 at $DIR/region-subtyping-basic.rs:23:18: 23:19
-        _0 = const ConstValue(Scalar(<ZST>): ()); // bb5[1]: scope 3 at $DIR/region-subtyping-basic.rs:22:12: 24:6
+        _0 = const ConstValue(ZeroSized: ()); // bb5[1]: scope 3 at $DIR/region-subtyping-basic.rs:22:12: 24:6
         goto -> bb6;                     // bb5[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:5: 24:6
     }
 
diff --git a/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.64bit.mir b/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.64bit.mir
index c555e0441f423..2f9dff00b631b 100644
--- a/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.64bit.mir
+++ b/src/test/mir-opt/nll/region_subtyping_basic.main.nll.0.64bit.mir
@@ -70,30 +70,30 @@ fn main() -> () {
         StorageLive(_8);                 // bb2[0]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
         StorageLive(_9);                 // bb2[1]: scope 3 at $DIR/region-subtyping-basic.rs:21:15: 21:17
         _9 = (*_6);                      // bb2[2]: scope 3 at $DIR/region-subtyping-basic.rs:21:15: 21:17
-        _8 = ConstValue(Scalar(<ZST>): fn(usize) -> bool {use_x})(move _9) -> [return: bb3, unwind: bb7]; // bb2[3]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
+        _8 = ConstValue(ZeroSized: fn(usize) -> bool {use_x})(move _9) -> [return: bb3, unwind: bb7]; // bb2[3]: scope 3 at $DIR/region-subtyping-basic.rs:21:9: 21:18
                                          // mir::Constant
                                          // + span: $DIR/region-subtyping-basic.rs:21:9: 21:14
-                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(<ZST>) }
     }
 
     bb3: {
         StorageDead(_9);                 // bb3[0]: scope 3 at $DIR/region-subtyping-basic.rs:21:17: 21:18
         StorageDead(_8);                 // bb3[1]: scope 3 at $DIR/region-subtyping-basic.rs:21:18: 21:19
-        _0 = const ConstValue(Scalar(<ZST>): ()); // bb3[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:13: 22:6
+        _0 = const ConstValue(ZeroSized: ()); // bb3[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:13: 22:6
         goto -> bb6;                     // bb3[3]: scope 3 at $DIR/region-subtyping-basic.rs:20:5: 24:6
     }
 
     bb4: {
         StorageLive(_10);                // bb4[0]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
-        _10 = ConstValue(Scalar(<ZST>): fn(usize) -> bool {use_x})(const ConstValue(Scalar(0x0000000000000016): usize)) -> [return: bb5, unwind: bb7]; // bb4[1]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
+        _10 = ConstValue(ZeroSized: fn(usize) -> bool {use_x})(const ConstValue(Scalar(0x0000000000000016): usize)) -> [return: bb5, unwind: bb7]; // bb4[1]: scope 3 at $DIR/region-subtyping-basic.rs:23:9: 23:18
                                          // mir::Constant
                                          // + span: $DIR/region-subtyping-basic.rs:23:9: 23:14
-                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(usize) -> bool {use_x}, val: Value(<ZST>) }
     }
 
     bb5: {
         StorageDead(_10);                // bb5[0]: scope 3 at $DIR/region-subtyping-basic.rs:23:18: 23:19
-        _0 = const ConstValue(Scalar(<ZST>): ()); // bb5[1]: scope 3 at $DIR/region-subtyping-basic.rs:22:12: 24:6
+        _0 = const ConstValue(ZeroSized: ()); // bb5[1]: scope 3 at $DIR/region-subtyping-basic.rs:22:12: 24:6
         goto -> bb6;                     // bb5[2]: scope 3 at $DIR/region-subtyping-basic.rs:20:5: 24:6
     }
 
diff --git a/src/test/mir-opt/no_drop_for_inactive_variant.unwrap.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/no_drop_for_inactive_variant.unwrap.SimplifyCfg-elaborate-drops.after.mir
index 8a297cea2b956..fda6cd6120771 100644
--- a/src/test/mir-opt/no_drop_for_inactive_variant.unwrap.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/no_drop_for_inactive_variant.unwrap.SimplifyCfg-elaborate-drops.after.mir
@@ -23,7 +23,7 @@ fn unwrap(_1: Option<T>) -> T {
         _4 = begin_panic::<&str>(const "explicit panic") -> bb4; // scope 0 at $SRC_DIR/std/src/panic.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-                                         // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(<ZST>) }
                                          // mir::Constant
                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
                                          // + literal: Const { ty: &str, val: Value(Slice(..)) }
diff --git a/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir b/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
index bdab2d9322210..0c814fd9d8dda 100644
--- a/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
+++ b/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
@@ -20,7 +20,7 @@ fn main() -> () {
         _2 = <str as ToString>::to_string(move _3) -> bb1; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
                                          // mir::Constant
                                          // + span: $DIR/no-spurious-drop-after-call.rs:9:23: 9:32
-                                         // + literal: Const { ty: for<'r> fn(&'r str) -> String {<str as ToString>::to_string}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r str) -> String {<str as ToString>::to_string}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -28,7 +28,7 @@ fn main() -> () {
         _1 = std::mem::drop::<String>(move _2) -> [return: bb2, unwind: bb3]; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:5: 9:35
                                          // mir::Constant
                                          // + span: $DIR/no-spurious-drop-after-call.rs:9:5: 9:19
-                                         // + literal: Const { ty: fn(String) {std::mem::drop::<String>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(String) {std::mem::drop::<String>}, val: Value(<ZST>) }
     }
 
     bb2: {
diff --git a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
index 5bf8655fcecdc..8ee81e679ec47 100644
--- a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
+++ b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
@@ -32,7 +32,7 @@ fn main() -> () {
         _1 = null_mut::<Test>() -> [return: bb1, unwind: bb4]; // scope 0 at $DIR/receiver-ptr-mutability.rs:14:26: 14:46
                                          // mir::Constant
                                          // + span: $DIR/receiver-ptr-mutability.rs:14:26: 14:44
-                                         // + literal: Const { ty: fn() -> *mut Test {null_mut::<Test>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> *mut Test {null_mut::<Test>}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -47,7 +47,7 @@ fn main() -> () {
         _2 = Test::x(move _3) -> [return: bb2, unwind: bb4]; // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
                                          // mir::Constant
                                          // + span: $DIR/receiver-ptr-mutability.rs:15:9: 15:10
-                                         // + literal: Const { ty: fn(*const Test) {Test::x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(*const Test) {Test::x}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -75,7 +75,7 @@ fn main() -> () {
         _10 = Test::x(move _11) -> [return: bb3, unwind: bb4]; // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
                                          // mir::Constant
                                          // + span: $DIR/receiver-ptr-mutability.rs:19:13: 19:14
-                                         // + literal: Const { ty: fn(*const Test) {Test::x}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(*const Test) {Test::x}, val: Value(<ZST>) }
     }
 
     bb3: {
diff --git a/src/test/mir-opt/remove_storage_markers.main.RemoveStorageMarkers.diff b/src/test/mir-opt/remove_storage_markers.main.RemoveStorageMarkers.diff
index 447fe654c0cca..b2bfe4280b0af 100644
--- a/src/test/mir-opt/remove_storage_markers.main.RemoveStorageMarkers.diff
+++ b/src/test/mir-opt/remove_storage_markers.main.RemoveStorageMarkers.diff
@@ -60,7 +60,7 @@
           _7 = <std::ops::Range<i32> as iter::range::RangeIteratorImpl>::spec_next(move _14) -> bb4; // scope 5 at $SRC_DIR/core/src/iter/range.rs:LL:COL
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/iter/range.rs:LL:COL
-                                           // + literal: Const { ty: for<'r> fn(&'r mut std::ops::Range<i32>) -> Option<<std::ops::Range<i32> as iter::range::RangeIteratorImpl>::Item> {<std::ops::Range<i32> as iter::range::RangeIteratorImpl>::spec_next}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: for<'r> fn(&'r mut std::ops::Range<i32>) -> Option<<std::ops::Range<i32> as iter::range::RangeIteratorImpl>::Item> {<std::ops::Range<i32> as iter::range::RangeIteratorImpl>::spec_next}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
index c8c45da19137f..05e83b13a50c4 100644
--- a/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
@@ -81,7 +81,7 @@ fn array_casts() -> () {
         _6 = ptr::mut_ptr::<impl *mut usize>::add(move _7, const 1_usize) -> bb1; // scope 3 at $DIR/retag.rs:60:15: 60:23
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:60:17: 60:20
-                                         // + literal: Const { ty: unsafe fn(*mut usize, usize) -> *mut usize {ptr::mut_ptr::<impl *mut usize>::add}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(*mut usize, usize) -> *mut usize {ptr::mut_ptr::<impl *mut usize>::add}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -112,7 +112,7 @@ fn array_casts() -> () {
         _16 = ptr::const_ptr::<impl *const usize>::add(move _17, const 1_usize) -> bb2; // scope 6 at $DIR/retag.rs:64:26: 64:34
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:64:28: 64:31
-                                         // + literal: Const { ty: unsafe fn(*const usize, usize) -> *const usize {ptr::const_ptr::<impl *const usize>::add}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(*const usize, usize) -> *const usize {ptr::const_ptr::<impl *const usize>::add}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -176,7 +176,7 @@ fn array_casts() -> () {
         _28 = core::panicking::assert_failed::<usize, usize>(move _29, move _30, move _32, move _34); // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
-                                         // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r usize, &'s usize, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<usize, usize>}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r, 's, 't0> fn(core::panicking::AssertKind, &'r usize, &'s usize, Option<Arguments<'t0>>) -> ! {core::panicking::assert_failed::<usize, usize>}, val: Value(<ZST>) }
     }
 
     bb4: {
diff --git a/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir b/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
index 09cf06cacd920..8057aa13a9ffb 100644
--- a/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
+++ b/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
@@ -11,7 +11,7 @@ fn std::ptr::drop_in_place(_1: *mut Test) -> () {
         _3 = <Test as Drop>::drop(move _2) -> bb1; // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                                         // + literal: Const { ty: for<'r> fn(&'r mut Test) {<Test as Drop>::drop}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r mut Test) {<Test as Drop>::drop}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
index 2fda8c949b00c..722c1f82ac999 100644
--- a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
@@ -74,7 +74,7 @@ fn main() -> () {
         _3 = Test::foo(move _4, move _6) -> [return: bb1, unwind: bb8]; // scope 1 at $DIR/retag.rs:32:17: 32:36
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:32:25: 32:28
-                                         // + literal: Const { ty: for<'r, 'x> fn(&'r Test, &'x mut i32) -> &'x mut i32 {Test::foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r, 'x> fn(&'r Test, &'x mut i32) -> &'x mut i32 {Test::foo}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -159,7 +159,7 @@ fn main() -> () {
         _19 = Test::foo_shr(move _20, move _22) -> [return: bb4, unwind: bb7]; // scope 7 at $DIR/retag.rs:47:5: 47:24
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:47:13: 47:20
-                                         // + literal: Const { ty: for<'r, 'x> fn(&'r Test, &'x i32) -> &'x i32 {Test::foo_shr}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r, 'x> fn(&'r Test, &'x i32) -> &'x i32 {Test::foo_shr}, val: Value(<ZST>) }
     }
 
     bb4: {
@@ -183,7 +183,7 @@ fn main() -> () {
         _27 = array_casts() -> bb6;      // scope 8 at $DIR/retag.rs:52:5: 52:18
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:52:5: 52:16
-                                         // + literal: Const { ty: fn() {array_casts}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() {array_casts}, val: Value(<ZST>) }
     }
 
     bb6: {
diff --git a/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-early-opt.diff b/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-early-opt.diff
index 1c5a890023648..6d41d5b7437f5 100644
--- a/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-early-opt.diff
+++ b/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-early-opt.diff
@@ -21,7 +21,7 @@
 +         _2 = bar() -> [return: bb2, unwind: bb5]; // scope 0 at $DIR/simplify_cfg.rs:9:12: 9:17
                                            // mir::Constant
                                            // + span: $DIR/simplify_cfg.rs:9:12: 9:15
-                                           // + literal: Const { ty: fn() -> bool {bar}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {bar}, val: Value(<ZST>) }
       }
   
 -     bb3: {
diff --git a/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-initial.diff b/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-initial.diff
index b079bd7b57c42..78841d28b85b1 100644
--- a/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-initial.diff
+++ b/src/test/mir-opt/simplify_cfg.main.SimplifyCfg-initial.diff
@@ -22,7 +22,7 @@
 +         _2 = bar() -> [return: bb3, unwind: bb6]; // scope 0 at $DIR/simplify_cfg.rs:9:12: 9:17
                                            // mir::Constant
                                            // + span: $DIR/simplify_cfg.rs:9:12: 9:15
-                                           // + literal: Const { ty: fn() -> bool {bar}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> bool {bar}, val: Value(<ZST>) }
       }
   
       bb3: {
diff --git a/src/test/mir-opt/simplify_if.main.SimplifyConstCondition-after-const-prop.diff b/src/test/mir-opt/simplify_if.main.SimplifyConstCondition-after-const-prop.diff
index d11c70b1efec6..f729b53b20410 100644
--- a/src/test/mir-opt/simplify_if.main.SimplifyConstCondition-after-const-prop.diff
+++ b/src/test/mir-opt/simplify_if.main.SimplifyConstCondition-after-const-prop.diff
@@ -18,7 +18,7 @@
           _2 = noop() -> bb2;              // scope 0 at $DIR/simplify_if.rs:7:9: 7:15
                                            // mir::Constant
                                            // + span: $DIR/simplify_if.rs:7:9: 7:13
-                                           // + literal: Const { ty: fn() {noop}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {noop}, val: Value(<ZST>) }
       }
   
       bb2: {
diff --git a/src/test/mir-opt/simplify_locals_removes_unused_consts.main.SimplifyLocals.diff b/src/test/mir-opt/simplify_locals_removes_unused_consts.main.SimplifyLocals.diff
index 1bba1e9e88a4e..f4f1b9d4eb87e 100644
--- a/src/test/mir-opt/simplify_locals_removes_unused_consts.main.SimplifyLocals.diff
+++ b/src/test/mir-opt/simplify_locals_removes_unused_consts.main.SimplifyLocals.diff
@@ -15,7 +15,8 @@
 -     let mut _10: u8;                     // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:16:12: 16:30
 -     let mut _11: Temp;                   // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:16:12: 16:28
 +     let _1: ();                          // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
-+     let _2: ();                          // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
++     let mut _2: ((), ());                // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:14:13: 14:21
++     let _3: ();                          // in scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
       scope 1 {
       }
   
@@ -32,12 +33,13 @@
 -         StorageLive(_7);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:18: 14:20
 -         StorageDead(_7);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:20: 14:21
 -         StorageDead(_6);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:20: 14:21
--         _4 = use_zst(const ((), ())) -> bb1; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
+-         _4 = use_zst(move _5) -> bb1;    // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
 +         StorageLive(_1);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
-+         _1 = use_zst(const ((), ())) -> bb1; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
++         StorageLive(_2);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:13: 14:21
++         _1 = use_zst(move _2) -> bb1;    // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
                                            // mir::Constant
                                            // + span: $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:12
-                                           // + literal: Const { ty: fn(((), ())) {use_zst}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(((), ())) {use_zst}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -49,19 +51,20 @@
 -         StorageLive(_11);                // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:12: 16:28
 -         StorageDead(_10);                // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:33: 16:34
 -         _8 = use_u8(const 42_u8) -> bb2; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
++         StorageDead(_2);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:21: 14:22
 +         StorageDead(_1);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:22: 14:23
-+         StorageLive(_2);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
-+         _2 = use_u8(const 42_u8) -> bb2; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
++         StorageLive(_3);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
++         _3 = use_u8(const 42_u8) -> bb2; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:35
                                            // mir::Constant
                                            // + span: $DIR/simplify-locals-removes-unused-consts.rs:16:5: 16:11
-                                           // + literal: Const { ty: fn(u8) {use_u8}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn(u8) {use_u8}, val: Value(<ZST>) }
       }
   
       bb2: {
 -         StorageDead(_9);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:34: 16:35
 -         StorageDead(_11);                // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
 -         StorageDead(_8);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
-+         StorageDead(_2);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
++         StorageDead(_3);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
           return;                          // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:17:2: 17:2
       }
   }
diff --git a/src/test/mir-opt/simplify_match.main.ConstProp.diff b/src/test/mir-opt/simplify_match.main.ConstProp.diff
index 1c8d043a6030c..6314abe6f39db 100644
--- a/src/test/mir-opt/simplify_match.main.ConstProp.diff
+++ b/src/test/mir-opt/simplify_match.main.ConstProp.diff
@@ -29,7 +29,7 @@
           _0 = noop() -> bb3;              // scope 0 at $DIR/simplify_match.rs:7:17: 7:23
                                            // mir::Constant
                                            // + span: $DIR/simplify_match.rs:7:17: 7:21
-                                           // + literal: Const { ty: fn() {noop}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {noop}, val: Value(<ZST>) }
       }
   
       bb3: {
diff --git a/src/test/mir-opt/uniform_array_move_out.move_out_by_subslice.mir_map.0.mir b/src/test/mir-opt/uniform_array_move_out.move_out_by_subslice.mir_map.0.mir
index d7d2cdf9b0c75..d36d369003a63 100644
--- a/src/test/mir-opt/uniform_array_move_out.move_out_by_subslice.mir_map.0.mir
+++ b/src/test/mir-opt/uniform_array_move_out.move_out_by_subslice.mir_map.0.mir
@@ -33,7 +33,7 @@ fn move_out_by_subslice() -> () {
         _5 = alloc::alloc::exchange_malloc(move _3, move _4) -> [return: bb1, unwind: bb12]; // scope 2 at $DIR/uniform_array_move_out.rs:11:14: 11:19
                                          // mir::Constant
                                          // + span: $DIR/uniform_array_move_out.rs:11:14: 11:19
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -52,7 +52,7 @@ fn move_out_by_subslice() -> () {
         _10 = alloc::alloc::exchange_malloc(move _8, move _9) -> [return: bb3, unwind: bb11]; // scope 3 at $DIR/uniform_array_move_out.rs:11:21: 11:26
                                          // mir::Constant
                                          // + span: $DIR/uniform_array_move_out.rs:11:21: 11:26
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb3: {
diff --git a/src/test/mir-opt/uniform_array_move_out.move_out_from_end.mir_map.0.mir b/src/test/mir-opt/uniform_array_move_out.move_out_from_end.mir_map.0.mir
index 18bc1a17c1b50..e6c8b66c25af0 100644
--- a/src/test/mir-opt/uniform_array_move_out.move_out_from_end.mir_map.0.mir
+++ b/src/test/mir-opt/uniform_array_move_out.move_out_from_end.mir_map.0.mir
@@ -33,7 +33,7 @@ fn move_out_from_end() -> () {
         _5 = alloc::alloc::exchange_malloc(move _3, move _4) -> [return: bb1, unwind: bb12]; // scope 2 at $DIR/uniform_array_move_out.rs:5:14: 5:19
                                          // mir::Constant
                                          // + span: $DIR/uniform_array_move_out.rs:5:14: 5:19
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb1: {
@@ -52,7 +52,7 @@ fn move_out_from_end() -> () {
         _10 = alloc::alloc::exchange_malloc(move _8, move _9) -> [return: bb3, unwind: bb11]; // scope 3 at $DIR/uniform_array_move_out.rs:5:21: 5:26
                                          // mir::Constant
                                          // + span: $DIR/uniform_array_move_out.rs:5:21: 5:26
-                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: unsafe fn(usize, usize) -> *mut u8 {alloc::alloc::exchange_malloc}, val: Value(<ZST>) }
     }
 
     bb3: {
diff --git a/src/test/mir-opt/unreachable.main.UnreachablePropagation.diff b/src/test/mir-opt/unreachable.main.UnreachablePropagation.diff
index 70486f546d71b..5aa4f1b343249 100644
--- a/src/test/mir-opt/unreachable.main.UnreachablePropagation.diff
+++ b/src/test/mir-opt/unreachable.main.UnreachablePropagation.diff
@@ -22,7 +22,7 @@
           _1 = empty() -> bb1;             // scope 1 at $DIR/unreachable.rs:9:23: 9:30
                                            // mir::Constant
                                            // + span: $DIR/unreachable.rs:9:23: 9:28
-                                           // + literal: Const { ty: fn() -> Option<Empty> {empty}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> Option<Empty> {empty}, val: Value(<ZST>) }
       }
   
       bb1: {
diff --git a/src/test/mir-opt/unreachable_diverging.main.UnreachablePropagation.diff b/src/test/mir-opt/unreachable_diverging.main.UnreachablePropagation.diff
index d9f2681d145e6..b95ab881ef05d 100644
--- a/src/test/mir-opt/unreachable_diverging.main.UnreachablePropagation.diff
+++ b/src/test/mir-opt/unreachable_diverging.main.UnreachablePropagation.diff
@@ -24,7 +24,7 @@
           _2 = empty() -> bb1;             // scope 2 at $DIR/unreachable_diverging.rs:14:25: 14:32
                                            // mir::Constant
                                            // + span: $DIR/unreachable_diverging.rs:14:25: 14:30
-                                           // + literal: Const { ty: fn() -> Option<Empty> {empty}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() -> Option<Empty> {empty}, val: Value(<ZST>) }
       }
   
       bb1: {
@@ -48,7 +48,7 @@
 +         _5 = loop_forever() -> bb4;      // scope 2 at $DIR/unreachable_diverging.rs:16:13: 16:27
                                            // mir::Constant
                                            // + span: $DIR/unreachable_diverging.rs:16:13: 16:25
-                                           // + literal: Const { ty: fn() {loop_forever}, val: Value(Scalar(<ZST>)) }
+                                           // + literal: Const { ty: fn() {loop_forever}, val: Value(<ZST>) }
       }
   
       bb4: {
diff --git a/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.32bit.mir b/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.32bit.mir
index 5dc81b787a9fa..54ecaccdb4fb8 100644
--- a/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.32bit.mir
+++ b/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.32bit.mir
@@ -34,6 +34,6 @@ fn std::ptr::drop_in_place(_1: *mut Vec<i32>) -> () {
         _3 = <Vec<i32> as Drop>::drop(move _2) -> [return: bb5, unwind: bb4]; // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                                         // + literal: Const { ty: for<'r> fn(&'r mut Vec<i32>) {<Vec<i32> as Drop>::drop}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r mut Vec<i32>) {<Vec<i32> as Drop>::drop}, val: Value(<ZST>) }
     }
 }
diff --git a/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.64bit.mir b/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.64bit.mir
index 5dc81b787a9fa..54ecaccdb4fb8 100644
--- a/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.64bit.mir
+++ b/src/test/mir-opt/unusual_item_types.core.ptr-drop_in_place.Vec_i32_.AddMovesForPackedDrops.before.64bit.mir
@@ -34,6 +34,6 @@ fn std::ptr::drop_in_place(_1: *mut Vec<i32>) -> () {
         _3 = <Vec<i32> as Drop>::drop(move _2) -> [return: bb5, unwind: bb4]; // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/ptr/mod.rs:LL:COL
-                                         // + literal: Const { ty: for<'r> fn(&'r mut Vec<i32>) {<Vec<i32> as Drop>::drop}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: for<'r> fn(&'r mut Vec<i32>) {<Vec<i32> as Drop>::drop}, val: Value(<ZST>) }
     }
 }
diff --git a/src/test/mir-opt/while_storage.while_loop.PreCodegen.after.mir b/src/test/mir-opt/while_storage.while_loop.PreCodegen.after.mir
index ec2d161251b00..f1c5d95df1903 100644
--- a/src/test/mir-opt/while_storage.while_loop.PreCodegen.after.mir
+++ b/src/test/mir-opt/while_storage.while_loop.PreCodegen.after.mir
@@ -19,7 +19,7 @@ fn while_loop(_1: bool) -> () {
         _2 = get_bool(move _3) -> bb2;   // scope 0 at $DIR/while-storage.rs:10:11: 10:22
                                          // mir::Constant
                                          // + span: $DIR/while-storage.rs:10:11: 10:19
-                                         // + literal: Const { ty: fn(bool) -> bool {get_bool}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(bool) -> bool {get_bool}, val: Value(<ZST>) }
     }
 
     bb2: {
@@ -34,7 +34,7 @@ fn while_loop(_1: bool) -> () {
         _4 = get_bool(move _5) -> bb4;   // scope 0 at $DIR/while-storage.rs:11:12: 11:23
                                          // mir::Constant
                                          // + span: $DIR/while-storage.rs:11:12: 11:20
-                                         // + literal: Const { ty: fn(bool) -> bool {get_bool}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn(bool) -> bool {get_bool}, val: Value(<ZST>) }
     }
 
     bb4: {
diff --git a/src/test/run-make/const_fn_mir/dump.mir b/src/test/run-make/const_fn_mir/dump.mir
index f02bccc4b2da5..ab4084c952a3d 100644
--- a/src/test/run-make/const_fn_mir/dump.mir
+++ b/src/test/run-make/const_fn_mir/dump.mir
@@ -33,7 +33,7 @@ fn main() -> () {
         _1 = foo() -> bb1;               // scope 0 at main.rs:9:5: 9:10
                                          // mir::Constant
                                          // + span: main.rs:9:5: 9:8
-                                         // + literal: Const { ty: fn() -> i32 {foo}, val: Value(Scalar(<ZST>)) }
+                                         // + literal: Const { ty: fn() -> i32 {foo}, val: Value(<ZST>) }
     }
 
     bb1: {
diff --git a/src/test/run-make/issue-88756-default-output/output-default.stdout b/src/test/run-make/issue-88756-default-output/output-default.stdout
index 6d16fe5673bc1..08877af928657 100644
--- a/src/test/run-make/issue-88756-default-output/output-default.stdout
+++ b/src/test/run-make/issue-88756-default-output/output-default.stdout
@@ -110,6 +110,9 @@ Options:
                         never = never colorize output
         --error-format human|json|short
                         How errors and other messages are produced
+        --diagnostic-width WIDTH
+                        Provide width of the output for truncated error
+                        messages
         --json CONFIG   Configure the structure of JSON diagnostics
         --disable-minification 
                         Disable minification applied on JS files
diff --git a/src/test/rustdoc-ui/diagnostic-width.rs b/src/test/rustdoc-ui/diagnostic-width.rs
new file mode 100644
index 0000000000000..61961d5ec710e
--- /dev/null
+++ b/src/test/rustdoc-ui/diagnostic-width.rs
@@ -0,0 +1,5 @@
+// compile-flags: -Zunstable-options --diagnostic-width=10
+#![deny(rustdoc::bare_urls)]
+
+/// This is a long line that contains a http://link.com
+pub struct Foo; //~^ ERROR
diff --git a/src/test/rustdoc-ui/diagnostic-width.stderr b/src/test/rustdoc-ui/diagnostic-width.stderr
new file mode 100644
index 0000000000000..fed049d2b37bc
--- /dev/null
+++ b/src/test/rustdoc-ui/diagnostic-width.stderr
@@ -0,0 +1,15 @@
+error: this URL is not a hyperlink
+  --> $DIR/diagnostic-width.rs:4:41
+   |
+LL | ... a http://link.com
+   |       ^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://link.com>`
+   |
+note: the lint level is defined here
+  --> $DIR/diagnostic-width.rs:2:9
+   |
+LL | ...ny(rustdoc::bare_url...
+   |       ^^^^^^^^^^^^^^^^^^
+   = note: bare URLs are not automatically turned into clickable links
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/diagnostic-width/flag-human.rs b/src/test/ui/diagnostic-width/flag-human.rs
new file mode 100644
index 0000000000000..289bfbabd949b
--- /dev/null
+++ b/src/test/ui/diagnostic-width/flag-human.rs
@@ -0,0 +1,9 @@
+// compile-flags: --diagnostic-width=20
+
+// This test checks that `-Z output-width` effects the human error output by restricting it to an
+// arbitrarily low value so that the effect is visible.
+
+fn main() {
+    let _: () = 42;
+    //~^ ERROR mismatched types
+}
diff --git a/src/test/ui/terminal-width/flag-human.stderr b/src/test/ui/diagnostic-width/flag-human.stderr
similarity index 100%
rename from src/test/ui/terminal-width/flag-human.stderr
rename to src/test/ui/diagnostic-width/flag-human.stderr
diff --git a/src/test/ui/diagnostic-width/flag-json.rs b/src/test/ui/diagnostic-width/flag-json.rs
new file mode 100644
index 0000000000000..51a1fb447c7d2
--- /dev/null
+++ b/src/test/ui/diagnostic-width/flag-json.rs
@@ -0,0 +1,9 @@
+// compile-flags: --diagnostic-width=20 --error-format=json
+
+// This test checks that `-Z output-width` effects the JSON error output by restricting it to an
+// arbitrarily low value so that the effect is visible.
+
+fn main() {
+    let _: () = 42;
+    //~^ ERROR arguments to this function are incorrect
+}
diff --git a/src/test/ui/terminal-width/flag-json.stderr b/src/test/ui/diagnostic-width/flag-json.stderr
similarity index 93%
rename from src/test/ui/terminal-width/flag-json.stderr
rename to src/test/ui/diagnostic-width/flag-json.stderr
index 93c246cb3f501..b21391d1640ef 100644
--- a/src/test/ui/terminal-width/flag-json.stderr
+++ b/src/test/ui/diagnostic-width/flag-json.stderr
@@ -24,7 +24,7 @@ This error occurs when an expression was used in a place where the compiler
 expected an expression of a different type. It can occur in several cases, the
 most common being when calling a function and passing an argument which has a
 different type than the matching type in the function declaration.
-"},"level":"error","spans":[{"file_name":"$DIR/flag-json.rs","byte_start":244,"byte_end":246,"line_start":7,"line_end":7,"column_start":17,"column_end":19,"is_primary":true,"text":[{"text":"    let _: () = 42;","highlight_start":17,"highlight_end":19}],"label":"expected `()`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/flag-json.rs","byte_start":239,"byte_end":241,"line_start":7,"line_end":7,"column_start":12,"column_end":14,"is_primary":false,"text":[{"text":"    let _: () = 42;","highlight_start":12,"highlight_end":14}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0308]: mismatched types
+"},"level":"error","spans":[{"file_name":"$DIR/flag-json.rs","byte_start":243,"byte_end":245,"line_start":7,"line_end":7,"column_start":17,"column_end":19,"is_primary":true,"text":[{"text":"    let _: () = 42;","highlight_start":17,"highlight_end":19}],"label":"expected `()`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/flag-json.rs","byte_start":238,"byte_end":240,"line_start":7,"line_end":7,"column_start":12,"column_end":14,"is_primary":false,"text":[{"text":"    let _: () = 42;","highlight_start":12,"highlight_end":14}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0308]: mismatched types
   --> $DIR/flag-json.rs:7:17
    |
 LL | ..._: () = 42;
diff --git a/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.rs b/src/test/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs
similarity index 100%
rename from src/test/ui/terminal-width/non-1-width-unicode-multiline-label.rs
rename to src/test/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs
diff --git a/src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr b/src/test/ui/diagnostic-width/non-1-width-unicode-multiline-label.stderr
similarity index 100%
rename from src/test/ui/terminal-width/non-1-width-unicode-multiline-label.stderr
rename to src/test/ui/diagnostic-width/non-1-width-unicode-multiline-label.stderr
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming-2.rs b/src/test/ui/diagnostic-width/non-whitespace-trimming-2.rs
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming-2.rs
rename to src/test/ui/diagnostic-width/non-whitespace-trimming-2.rs
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming-2.stderr b/src/test/ui/diagnostic-width/non-whitespace-trimming-2.stderr
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming-2.stderr
rename to src/test/ui/diagnostic-width/non-whitespace-trimming-2.stderr
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming-unicode.rs b/src/test/ui/diagnostic-width/non-whitespace-trimming-unicode.rs
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming-unicode.rs
rename to src/test/ui/diagnostic-width/non-whitespace-trimming-unicode.rs
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming-unicode.stderr b/src/test/ui/diagnostic-width/non-whitespace-trimming-unicode.stderr
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming-unicode.stderr
rename to src/test/ui/diagnostic-width/non-whitespace-trimming-unicode.stderr
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming.rs b/src/test/ui/diagnostic-width/non-whitespace-trimming.rs
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming.rs
rename to src/test/ui/diagnostic-width/non-whitespace-trimming.rs
diff --git a/src/test/ui/terminal-width/non-whitespace-trimming.stderr b/src/test/ui/diagnostic-width/non-whitespace-trimming.stderr
similarity index 100%
rename from src/test/ui/terminal-width/non-whitespace-trimming.stderr
rename to src/test/ui/diagnostic-width/non-whitespace-trimming.stderr
diff --git a/src/test/ui/terminal-width/tabs-trimming.rs b/src/test/ui/diagnostic-width/tabs-trimming.rs
similarity index 100%
rename from src/test/ui/terminal-width/tabs-trimming.rs
rename to src/test/ui/diagnostic-width/tabs-trimming.rs
diff --git a/src/test/ui/terminal-width/tabs-trimming.stderr b/src/test/ui/diagnostic-width/tabs-trimming.stderr
similarity index 100%
rename from src/test/ui/terminal-width/tabs-trimming.stderr
rename to src/test/ui/diagnostic-width/tabs-trimming.stderr
diff --git a/src/test/ui/terminal-width/whitespace-trimming-2.rs b/src/test/ui/diagnostic-width/whitespace-trimming-2.rs
similarity index 100%
rename from src/test/ui/terminal-width/whitespace-trimming-2.rs
rename to src/test/ui/diagnostic-width/whitespace-trimming-2.rs
diff --git a/src/test/ui/terminal-width/whitespace-trimming-2.stderr b/src/test/ui/diagnostic-width/whitespace-trimming-2.stderr
similarity index 100%
rename from src/test/ui/terminal-width/whitespace-trimming-2.stderr
rename to src/test/ui/diagnostic-width/whitespace-trimming-2.stderr
diff --git a/src/test/ui/terminal-width/whitespace-trimming.rs b/src/test/ui/diagnostic-width/whitespace-trimming.rs
similarity index 100%
rename from src/test/ui/terminal-width/whitespace-trimming.rs
rename to src/test/ui/diagnostic-width/whitespace-trimming.rs
diff --git a/src/test/ui/terminal-width/whitespace-trimming.stderr b/src/test/ui/diagnostic-width/whitespace-trimming.stderr
similarity index 100%
rename from src/test/ui/terminal-width/whitespace-trimming.stderr
rename to src/test/ui/diagnostic-width/whitespace-trimming.stderr
diff --git a/src/test/ui/rfc-2294-if-let-guard/feature-gate.rs b/src/test/ui/rfc-2294-if-let-guard/feature-gate.rs
index bb1aff70d8995..d8febd273c96e 100644
--- a/src/test/ui/rfc-2294-if-let-guard/feature-gate.rs
+++ b/src/test/ui/rfc-2294-if-let-guard/feature-gate.rs
@@ -9,9 +9,11 @@ fn _if_let_guard() {
 
         () if (let 0 = 1) => {}
         //~^ ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
 
         () if (((let 0 = 1))) => {}
         //~^ ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
 
         () if true && let 0 = 1 => {}
         //~^ ERROR `if let` guards are experimental
@@ -23,13 +25,17 @@ fn _if_let_guard() {
 
         () if (let 0 = 1) && true => {}
         //~^ ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
 
         () if true && (let 0 = 1) => {}
         //~^ ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
 
         () if (let 0 = 1) && (let 0 = 1) => {}
         //~^ ERROR `let` expressions in this position are unstable
         //~| ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
+        //~| ERROR expected expression, found `let` statement
 
         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
         //~^ ERROR `if let` guards are experimental
@@ -38,6 +44,7 @@ fn _if_let_guard() {
         //~| ERROR `let` expressions in this position are unstable
         //~| ERROR `let` expressions in this position are unstable
         //~| ERROR `let` expressions in this position are unstable
+        //~| ERROR expected expression, found `let` statement
 
         () if let Range { start: _, end: _ } = (true..true) && false => {}
         //~^ ERROR `if let` guards are experimental
diff --git a/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr b/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
index 370a57318fdd0..52b5bca628ac7 100644
--- a/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
+++ b/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
@@ -1,17 +1,59 @@
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:59:16
+  --> $DIR/feature-gate.rs:10:16
+   |
+LL |         () if (let 0 = 1) => {}
+   |                ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:14:18
+   |
+LL |         () if (((let 0 = 1))) => {}
+   |                  ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:26:16
+   |
+LL |         () if (let 0 = 1) && true => {}
+   |                ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:30:24
+   |
+LL |         () if true && (let 0 = 1) => {}
+   |                        ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:34:16
+   |
+LL |         () if (let 0 = 1) && (let 0 = 1) => {}
+   |                ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:34:31
+   |
+LL |         () if (let 0 = 1) && (let 0 = 1) => {}
+   |                               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:40:42
+   |
+LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
+   |                                          ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/feature-gate.rs:66:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:62:16
+  --> $DIR/feature-gate.rs:69:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^
 
 error: no rules expected the token `let`
-  --> $DIR/feature-gate.rs:71:15
+  --> $DIR/feature-gate.rs:78:15
    |
 LL |     macro_rules! use_expr {
    |     --------------------- when calling this macro
@@ -30,7 +72,7 @@ LL |         () if let 0 = 1 => {}
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:16:12
+  --> $DIR/feature-gate.rs:18:12
    |
 LL |         () if true && let 0 = 1 => {}
    |            ^^^^^^^^^^^^^^^^^^^^
@@ -40,7 +82,7 @@ LL |         () if true && let 0 = 1 => {}
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:20:12
+  --> $DIR/feature-gate.rs:22:12
    |
 LL |         () if let 0 = 1 && true => {}
    |            ^^^^^^^^^^^^^^^^^^^^
@@ -50,7 +92,7 @@ LL |         () if let 0 = 1 && true => {}
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:34:12
+  --> $DIR/feature-gate.rs:40:12
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -60,7 +102,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:42:12
+  --> $DIR/feature-gate.rs:49:12
    |
 LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -70,7 +112,7 @@ LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
 
 error[E0658]: `if let` guards are experimental
-  --> $DIR/feature-gate.rs:67:12
+  --> $DIR/feature-gate.rs:74:12
    |
 LL |         () if let 0 = 1 => {}
    |            ^^^^^^^^^^^^
@@ -89,7 +131,7 @@ LL |         () if (let 0 = 1) => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:13:18
+  --> $DIR/feature-gate.rs:14:18
    |
 LL |         () if (((let 0 = 1))) => {}
    |                  ^^^^^^^^^
@@ -98,7 +140,7 @@ LL |         () if (((let 0 = 1))) => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:16:23
+  --> $DIR/feature-gate.rs:18:23
    |
 LL |         () if true && let 0 = 1 => {}
    |                       ^^^^^^^^^
@@ -107,7 +149,7 @@ LL |         () if true && let 0 = 1 => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:20:15
+  --> $DIR/feature-gate.rs:22:15
    |
 LL |         () if let 0 = 1 && true => {}
    |               ^^^^^^^^^
@@ -116,7 +158,7 @@ LL |         () if let 0 = 1 && true => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:24:16
+  --> $DIR/feature-gate.rs:26:16
    |
 LL |         () if (let 0 = 1) && true => {}
    |                ^^^^^^^^^
@@ -125,7 +167,7 @@ LL |         () if (let 0 = 1) && true => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:27:24
+  --> $DIR/feature-gate.rs:30:24
    |
 LL |         () if true && (let 0 = 1) => {}
    |                        ^^^^^^^^^
@@ -134,7 +176,7 @@ LL |         () if true && (let 0 = 1) => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:30:16
+  --> $DIR/feature-gate.rs:34:16
    |
 LL |         () if (let 0 = 1) && (let 0 = 1) => {}
    |                ^^^^^^^^^
@@ -143,7 +185,7 @@ LL |         () if (let 0 = 1) && (let 0 = 1) => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:30:31
+  --> $DIR/feature-gate.rs:34:31
    |
 LL |         () if (let 0 = 1) && (let 0 = 1) => {}
    |                               ^^^^^^^^^
@@ -152,7 +194,7 @@ LL |         () if (let 0 = 1) && (let 0 = 1) => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:34:15
+  --> $DIR/feature-gate.rs:40:15
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |               ^^^^^^^^^
@@ -161,7 +203,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:34:28
+  --> $DIR/feature-gate.rs:40:28
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |                            ^^^^^^^^^
@@ -170,7 +212,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:34:42
+  --> $DIR/feature-gate.rs:40:42
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |                                          ^^^^^^^^^
@@ -179,7 +221,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:34:55
+  --> $DIR/feature-gate.rs:40:55
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |                                                       ^^^^^^^^^
@@ -188,7 +230,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:34:68
+  --> $DIR/feature-gate.rs:40:68
    |
 LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) => {}
    |                                                                    ^^^^^^^^^
@@ -197,7 +239,7 @@ LL |         () if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 =
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:42:15
+  --> $DIR/feature-gate.rs:49:15
    |
 LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -206,7 +248,7 @@ LL |         () if let Range { start: _, end: _ } = (true..true) && false => {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:59:16
+  --> $DIR/feature-gate.rs:66:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^^^^^^^
@@ -215,7 +257,7 @@ LL |     use_expr!((let 0 = 1 && 0 == 0));
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:62:16
+  --> $DIR/feature-gate.rs:69:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^^^^^^^
@@ -223,6 +265,6 @@ LL |     use_expr!((let 0 = 1));
    = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
-error: aborting due to 25 previous errors
+error: aborting due to 32 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.rs b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.rs
index 36b730505c29e..069d2dc414dea 100644
--- a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.rs
+++ b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.rs
@@ -28,47 +28,61 @@ fn main() {}
 fn _if() {
     if (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     if (((let 0 = 1))) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     if (let 0 = 1) && true {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     if true && (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     if (let 0 = 1) && (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
 
     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 }
 
 fn _while() {
     while (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     while (((let 0 = 1))) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     while (let 0 = 1) && true {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     while true && (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 
     while (let 0 = 1) && (let 0 = 1) {}
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
 
     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 }
 
 fn _macros() {
@@ -89,39 +103,64 @@ fn _macros() {
 }
 
 fn nested_within_if_expr() {
-    if &let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    if &let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
-    if !let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    if *let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR type `bool` cannot be dereferenced
-    if -let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR cannot apply unary operator `-` to type `bool`
+    if !let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    if *let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR type `bool` cannot be dereferenced
+    //~| ERROR expected expression, found `let` statement
+    if -let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR cannot apply unary operator `-` to type `bool`
+    //~| ERROR expected expression, found `let` statement
 
     fn _check_try_binds_tighter() -> Result<(), ()> {
         if let 0 = 0? {}
         //~^ ERROR the `?` operator can only be applied to values that implement `Try`
         Ok(())
     }
-    if (let 0 = 0)? {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR the `?` operator can only be applied to values that implement `Try`
+    if (let 0 = 0)? {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR the `?` operator can only be applied to values that implement `Try`
     //~| ERROR the `?` operator can only be used in a function that returns `Result`
+    //~| ERROR expected expression, found `let` statement
 
-    if true || let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    if (true || let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    if true && (true || let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    if true || (true && let 0 = 0) {} //~ ERROR `let` expressions are not supported here
+    if true || let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    if (true || let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    if true && (true || let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    if true || (true && let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
 
     let mut x = true;
-    if x = let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    if x = let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
-    if true..(let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
-    if ..(let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
-    if (let 0 = 0).. {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    if true..(let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
+    if ..(let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
+    if (let 0 = 0).. {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
     // Binds as `(let ... = true)..true &&/|| false`.
     if let Range { start: _, end: _ } = true..true && false {}
@@ -151,42 +190,68 @@ fn nested_within_if_expr() {
 
     if let true = let true = true {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 }
 
 fn nested_within_while_expr() {
-    while &let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    while &let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
-    while !let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    while *let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR type `bool` cannot be dereferenced
-    while -let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR cannot apply unary operator `-` to type `bool`
+    while !let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    while *let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR type `bool` cannot be dereferenced
+    //~| ERROR expected expression, found `let` statement
+    while -let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR cannot apply unary operator `-` to type `bool`
+    //~| ERROR expected expression, found `let` statement
 
     fn _check_try_binds_tighter() -> Result<(), ()> {
         while let 0 = 0? {}
         //~^ ERROR the `?` operator can only be applied to values that implement `Try`
         Ok(())
     }
-    while (let 0 = 0)? {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR the `?` operator can only be applied to values that implement `Try`
+    while (let 0 = 0)? {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR the `?` operator can only be applied to values that implement `Try`
     //~| ERROR the `?` operator can only be used in a function that returns `Result`
+    //~| ERROR expected expression, found `let` statement
 
-    while true || let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    while (true || let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    while true && (true || let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    while true || (true && let 0 = 0) {} //~ ERROR `let` expressions are not supported here
+    while true || let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    while (true || let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    while true && (true || let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    while true || (true && let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
 
     let mut x = true;
-    while x = let 0 = 0 {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    while x = let 0 = 0 {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
-    while true..(let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
-    while ..(let 0 = 0) {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
-    while (let 0 = 0).. {} //~ ERROR `let` expressions are not supported here
-    //~^ ERROR mismatched types
+    while true..(let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
+    while ..(let 0 = 0) {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
+    while (let 0 = 0).. {}
+    //~^ ERROR `let` expressions are not supported here
+    //~| ERROR mismatched types
+    //~| ERROR expected expression, found `let` statement
 
     // Binds as `(let ... = true)..true &&/|| false`.
     while let Range { start: _, end: _ } = true..true && false {}
@@ -216,6 +281,7 @@ fn nested_within_while_expr() {
 
     while let true = let true = true {}
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
 }
 
 fn not_error_because_clarified_intent() {
@@ -316,15 +382,18 @@ fn inside_const_generic_arguments() {
     impl<const B: bool> A<{B}> { const O: u32 = 5; }
 
     if let A::<{
-        true && let 1 = 1 //~ ERROR `let` expressions are not supported here
+        true && let 1 = 1
+        //~^ ERROR `let` expressions are not supported here
     }>::O = 5 {}
 
     while let A::<{
-        true && let 1 = 1 //~ ERROR `let` expressions are not supported here
+        true && let 1 = 1
+        //~^ ERROR `let` expressions are not supported here
     }>::O = 5 {}
 
     if A::<{
-        true && let 1 = 1 //~ ERROR `let` expressions are not supported here
+        true && let 1 = 1
+        //~^ ERROR `let` expressions are not supported here
     }>::O == 5 {}
 
     // In the cases above we have `ExprKind::Block` to help us out.
@@ -345,14 +414,18 @@ fn with_parenthesis() {
 
     if (let Some(a) = opt && true) {
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
     }
 
     if (let Some(a) = opt) && true {
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
     }
     if (let Some(a) = opt) && (let Some(b) = a) {
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
     }
     if let Some(a) = opt && (true && true) {
     }
@@ -360,13 +433,18 @@ fn with_parenthesis() {
     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
     }
     if (let Some(a) = opt && (let Some(b) = a)) && true {
     //~^ ERROR `let` expressions are not supported here
     //~| ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
+    //~| ERROR expected expression, found `let` statement
     }
     if (let Some(a) = opt && (true)) && true {
     //~^ ERROR `let` expressions are not supported here
+    //~| ERROR expected expression, found `let` statement
     }
 
     if (true && (true)) && let Some(a) = opt {
diff --git a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
index 5cf06cf4b27cd..20512e8ee31aa 100644
--- a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
+++ b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
@@ -1,113 +1,353 @@
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:232:6
+  --> $DIR/disallowed-positions.rs:29:9
+   |
+LL |     if (let 0 = 1) {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:33:11
+   |
+LL |     if (((let 0 = 1))) {}
+   |           ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:37:9
+   |
+LL |     if (let 0 = 1) && true {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:41:17
+   |
+LL |     if true && (let 0 = 1) {}
+   |                 ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:45:9
+   |
+LL |     if (let 0 = 1) && (let 0 = 1) {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:45:24
+   |
+LL |     if (let 0 = 1) && (let 0 = 1) {}
+   |                        ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:51:35
+   |
+LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
+   |                                   ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:59:12
+   |
+LL |     while (let 0 = 1) {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:63:14
+   |
+LL |     while (((let 0 = 1))) {}
+   |              ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:67:12
+   |
+LL |     while (let 0 = 1) && true {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:71:20
+   |
+LL |     while true && (let 0 = 1) {}
+   |                    ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:75:12
+   |
+LL |     while (let 0 = 1) && (let 0 = 1) {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:75:27
+   |
+LL |     while (let 0 = 1) && (let 0 = 1) {}
+   |                           ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:81:38
+   |
+LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
+   |                                      ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:106:9
+   |
+LL |     if &let 0 = 0 {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:111:9
+   |
+LL |     if !let 0 = 0 {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:114:9
+   |
+LL |     if *let 0 = 0 {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:118:9
+   |
+LL |     if -let 0 = 0 {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:128:9
+   |
+LL |     if (let 0 = 0)? {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:134:16
+   |
+LL |     if true || let 0 = 0 {}
+   |                ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:137:17
+   |
+LL |     if (true || let 0 = 0) {}
+   |                 ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:140:25
+   |
+LL |     if true && (true || let 0 = 0) {}
+   |                         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:147:12
+   |
+LL |     if x = let 0 = 0 {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:152:15
+   |
+LL |     if true..(let 0 = 0) {}
+   |               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:156:11
+   |
+LL |     if ..(let 0 = 0) {}
+   |           ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:160:9
+   |
+LL |     if (let 0 = 0).. {}
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:191:19
+   |
+LL |     if let true = let true = true {}
+   |                   ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:197:12
+   |
+LL |     while &let 0 = 0 {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:202:12
+   |
+LL |     while !let 0 = 0 {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:205:12
+   |
+LL |     while *let 0 = 0 {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:209:12
+   |
+LL |     while -let 0 = 0 {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:219:12
+   |
+LL |     while (let 0 = 0)? {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:225:19
+   |
+LL |     while true || let 0 = 0 {}
+   |                   ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:228:20
+   |
+LL |     while (true || let 0 = 0) {}
+   |                    ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:231:28
+   |
+LL |     while true && (true || let 0 = 0) {}
+   |                            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:238:15
+   |
+LL |     while x = let 0 = 0 {}
+   |               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:243:18
+   |
+LL |     while true..(let 0 = 0) {}
+   |                  ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:247:14
+   |
+LL |     while ..(let 0 = 0) {}
+   |              ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:251:12
+   |
+LL |     while (let 0 = 0).. {}
+   |            ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:282:22
+   |
+LL |     while let true = let true = true {}
+   |                      ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:298:6
    |
 LL |     &let 0 = 0;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:236:6
+  --> $DIR/disallowed-positions.rs:302:6
    |
 LL |     !let 0 = 0;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:239:6
+  --> $DIR/disallowed-positions.rs:305:6
    |
 LL |     *let 0 = 0;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:243:6
+  --> $DIR/disallowed-positions.rs:309:6
    |
 LL |     -let 0 = 0;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:253:6
+  --> $DIR/disallowed-positions.rs:319:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:259:13
+  --> $DIR/disallowed-positions.rs:325:13
    |
 LL |     true || let 0 = 0;
    |             ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:262:14
+  --> $DIR/disallowed-positions.rs:328:14
    |
 LL |     (true || let 0 = 0);
    |              ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:265:22
+  --> $DIR/disallowed-positions.rs:331:22
    |
 LL |     true && (true || let 0 = 0);
    |                      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:270:9
+  --> $DIR/disallowed-positions.rs:336:9
    |
 LL |     x = let 0 = 0;
    |         ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:274:12
+  --> $DIR/disallowed-positions.rs:340:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:277:8
+  --> $DIR/disallowed-positions.rs:343:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:280:6
+  --> $DIR/disallowed-positions.rs:346:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:284:6
+  --> $DIR/disallowed-positions.rs:350:6
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:289:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     (let true = let true = true);
    |      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:289:17
+  --> $DIR/disallowed-positions.rs:355:17
    |
 LL |     (let true = let true = true);
    |                 ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:296:25
+  --> $DIR/disallowed-positions.rs:362:25
    |
 LL |         let x = true && let y = 1;
    |                         ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:302:19
+  --> $DIR/disallowed-positions.rs:368:19
    |
 LL |         [1, 2, 3][let _ = ()]
    |                   ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:307:6
+  --> $DIR/disallowed-positions.rs:373:6
    |
 LL |     &let 0 = 0
    |      ^^^
 
 error: expressions must be enclosed in braces to be used as const generic arguments
-  --> $DIR/disallowed-positions.rs:337:9
+  --> $DIR/disallowed-positions.rs:406:9
    |
 LL |         true && let 1 = 1
    |         ^^^^^^^^^^^^^^^^^
@@ -118,25 +358,79 @@ LL |         { true && let 1 = 1 }
    |         +                   +
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:384:22
+  --> $DIR/disallowed-positions.rs:415:9
+   |
+LL |     if (let Some(a) = opt && true) {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:420:9
+   |
+LL |     if (let Some(a) = opt) && true {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:424:9
+   |
+LL |     if (let Some(a) = opt) && (let Some(b) = a) {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:424:32
+   |
+LL |     if (let Some(a) = opt) && (let Some(b) = a) {
+   |                                ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:433:9
+   |
+LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:433:31
+   |
+LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
+   |                               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:439:9
+   |
+LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:439:31
+   |
+LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
+   |                               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:445:9
+   |
+LL |     if (let Some(a) = opt && (true)) && true {
+   |         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/disallowed-positions.rs:462:22
    |
 LL |     let x = (true && let y = 1);
    |                      ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:389:20
+  --> $DIR/disallowed-positions.rs:467:20
    |
 LL |         ([1, 2, 3][let _ = ()])
    |                    ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:81:16
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/disallowed-positions.rs:85:16
+  --> $DIR/disallowed-positions.rs:99:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^
@@ -155,280 +449,280 @@ LL |     if (let 0 = 1) {}
    |         ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:32:11
+  --> $DIR/disallowed-positions.rs:33:11
    |
 LL |     if (((let 0 = 1))) {}
    |           ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:32:11
+  --> $DIR/disallowed-positions.rs:33:11
    |
 LL |     if (((let 0 = 1))) {}
    |           ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:35:9
+  --> $DIR/disallowed-positions.rs:37:9
    |
 LL |     if (let 0 = 1) && true {}
    |         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:35:9
+  --> $DIR/disallowed-positions.rs:37:9
    |
 LL |     if (let 0 = 1) && true {}
    |         ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:38:17
+  --> $DIR/disallowed-positions.rs:41:17
    |
 LL |     if true && (let 0 = 1) {}
    |                 ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:38:17
+  --> $DIR/disallowed-positions.rs:41:17
    |
 LL |     if true && (let 0 = 1) {}
    |                 ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:41:9
+  --> $DIR/disallowed-positions.rs:45:9
    |
 LL |     if (let 0 = 1) && (let 0 = 1) {}
    |         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:41:9
+  --> $DIR/disallowed-positions.rs:45:9
    |
 LL |     if (let 0 = 1) && (let 0 = 1) {}
    |         ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:41:24
+  --> $DIR/disallowed-positions.rs:45:24
    |
 LL |     if (let 0 = 1) && (let 0 = 1) {}
    |                        ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:41:24
+  --> $DIR/disallowed-positions.rs:45:24
    |
 LL |     if (let 0 = 1) && (let 0 = 1) {}
    |                        ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:45:35
+  --> $DIR/disallowed-positions.rs:51:35
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:45:35
+  --> $DIR/disallowed-positions.rs:51:35
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:45:48
+  --> $DIR/disallowed-positions.rs:51:48
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:45:35
+  --> $DIR/disallowed-positions.rs:51:35
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:45:61
+  --> $DIR/disallowed-positions.rs:51:61
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                                             ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:45:35
+  --> $DIR/disallowed-positions.rs:51:35
    |
 LL |     if let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:52:12
+  --> $DIR/disallowed-positions.rs:59:12
    |
 LL |     while (let 0 = 1) {}
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:52:12
+  --> $DIR/disallowed-positions.rs:59:12
    |
 LL |     while (let 0 = 1) {}
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:55:14
+  --> $DIR/disallowed-positions.rs:63:14
    |
 LL |     while (((let 0 = 1))) {}
    |              ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:55:14
+  --> $DIR/disallowed-positions.rs:63:14
    |
 LL |     while (((let 0 = 1))) {}
    |              ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:58:12
+  --> $DIR/disallowed-positions.rs:67:12
    |
 LL |     while (let 0 = 1) && true {}
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:58:12
+  --> $DIR/disallowed-positions.rs:67:12
    |
 LL |     while (let 0 = 1) && true {}
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:61:20
+  --> $DIR/disallowed-positions.rs:71:20
    |
 LL |     while true && (let 0 = 1) {}
    |                    ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:61:20
+  --> $DIR/disallowed-positions.rs:71:20
    |
 LL |     while true && (let 0 = 1) {}
    |                    ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:64:12
+  --> $DIR/disallowed-positions.rs:75:12
    |
 LL |     while (let 0 = 1) && (let 0 = 1) {}
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:64:12
+  --> $DIR/disallowed-positions.rs:75:12
    |
 LL |     while (let 0 = 1) && (let 0 = 1) {}
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:64:27
+  --> $DIR/disallowed-positions.rs:75:27
    |
 LL |     while (let 0 = 1) && (let 0 = 1) {}
    |                           ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:64:27
+  --> $DIR/disallowed-positions.rs:75:27
    |
 LL |     while (let 0 = 1) && (let 0 = 1) {}
    |                           ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:68:38
+  --> $DIR/disallowed-positions.rs:81:38
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                      ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:68:38
+  --> $DIR/disallowed-positions.rs:81:38
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:68:51
+  --> $DIR/disallowed-positions.rs:81:51
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:68:38
+  --> $DIR/disallowed-positions.rs:81:38
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:68:64
+  --> $DIR/disallowed-positions.rs:81:64
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                                                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:68:38
+  --> $DIR/disallowed-positions.rs:81:38
    |
 LL |     while let 0 = 1 && let 1 = 2 && (let 2 = 3 && let 3 = 4 && let 4 = 5) {}
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:81:16
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:81:16
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:81:16
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:81:16
+  --> $DIR/disallowed-positions.rs:95:16
    |
 LL |     use_expr!((let 0 = 1 && 0 == 0));
    |                ^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:85:16
+  --> $DIR/disallowed-positions.rs:99:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:85:16
+  --> $DIR/disallowed-positions.rs:99:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:85:16
+  --> $DIR/disallowed-positions.rs:99:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:85:16
+  --> $DIR/disallowed-positions.rs:99:16
    |
 LL |     use_expr!((let 0 = 1));
    |                ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:92:9
+  --> $DIR/disallowed-positions.rs:106:9
    |
 LL |     if &let 0 = 0 {}
    |         ^^^^^^^^^
@@ -436,7 +730,7 @@ LL |     if &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:95:9
+  --> $DIR/disallowed-positions.rs:111:9
    |
 LL |     if !let 0 = 0 {}
    |         ^^^^^^^^^
@@ -444,7 +738,7 @@ LL |     if !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:96:9
+  --> $DIR/disallowed-positions.rs:114:9
    |
 LL |     if *let 0 = 0 {}
    |         ^^^^^^^^^
@@ -452,7 +746,7 @@ LL |     if *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:98:9
+  --> $DIR/disallowed-positions.rs:118:9
    |
 LL |     if -let 0 = 0 {}
    |         ^^^^^^^^^
@@ -460,72 +754,72 @@ LL |     if -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:106:9
+  --> $DIR/disallowed-positions.rs:128:9
    |
 LL |     if (let 0 = 0)? {}
    |         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:106:9
+  --> $DIR/disallowed-positions.rs:128:9
    |
 LL |     if (let 0 = 0)? {}
    |         ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:110:16
+  --> $DIR/disallowed-positions.rs:134:16
    |
 LL |     if true || let 0 = 0 {}
    |                ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:110:13
+  --> $DIR/disallowed-positions.rs:134:13
    |
 LL |     if true || let 0 = 0 {}
    |             ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:111:17
+  --> $DIR/disallowed-positions.rs:137:17
    |
 LL |     if (true || let 0 = 0) {}
    |                 ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:111:14
+  --> $DIR/disallowed-positions.rs:137:14
    |
 LL |     if (true || let 0 = 0) {}
    |              ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:112:25
+  --> $DIR/disallowed-positions.rs:140:25
    |
 LL |     if true && (true || let 0 = 0) {}
    |                         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:112:22
+  --> $DIR/disallowed-positions.rs:140:22
    |
 LL |     if true && (true || let 0 = 0) {}
    |                      ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:113:25
+  --> $DIR/disallowed-positions.rs:143:25
    |
 LL |     if true || (true && let 0 = 0) {}
    |                         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:113:17
+  --> $DIR/disallowed-positions.rs:143:17
    |
 LL |     if true || (true && let 0 = 0) {}
    |                 ^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:116:12
+  --> $DIR/disallowed-positions.rs:147:12
    |
 LL |     if x = let 0 = 0 {}
    |            ^^^^^^^^^
@@ -533,46 +827,46 @@ LL |     if x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:119:15
+  --> $DIR/disallowed-positions.rs:152:15
    |
 LL |     if true..(let 0 = 0) {}
    |               ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:119:15
+  --> $DIR/disallowed-positions.rs:152:15
    |
 LL |     if true..(let 0 = 0) {}
    |               ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:121:11
+  --> $DIR/disallowed-positions.rs:156:11
    |
 LL |     if ..(let 0 = 0) {}
    |           ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:121:11
+  --> $DIR/disallowed-positions.rs:156:11
    |
 LL |     if ..(let 0 = 0) {}
    |           ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:123:9
+  --> $DIR/disallowed-positions.rs:160:9
    |
 LL |     if (let 0 = 0).. {}
    |         ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:123:9
+  --> $DIR/disallowed-positions.rs:160:9
    |
 LL |     if (let 0 = 0).. {}
    |         ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:127:8
+  --> $DIR/disallowed-positions.rs:166:8
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -580,7 +874,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:131:8
+  --> $DIR/disallowed-positions.rs:170:8
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -588,7 +882,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:138:8
+  --> $DIR/disallowed-positions.rs:177:8
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -596,7 +890,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:146:8
+  --> $DIR/disallowed-positions.rs:185:8
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -604,7 +898,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:152:19
+  --> $DIR/disallowed-positions.rs:191:19
    |
 LL |     if let true = let true = true {}
    |                   ^^^^^^^^^^^^^^^
@@ -612,7 +906,7 @@ LL |     if let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:157:12
+  --> $DIR/disallowed-positions.rs:197:12
    |
 LL |     while &let 0 = 0 {}
    |            ^^^^^^^^^
@@ -620,7 +914,7 @@ LL |     while &let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:160:12
+  --> $DIR/disallowed-positions.rs:202:12
    |
 LL |     while !let 0 = 0 {}
    |            ^^^^^^^^^
@@ -628,7 +922,7 @@ LL |     while !let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:161:12
+  --> $DIR/disallowed-positions.rs:205:12
    |
 LL |     while *let 0 = 0 {}
    |            ^^^^^^^^^
@@ -636,7 +930,7 @@ LL |     while *let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:163:12
+  --> $DIR/disallowed-positions.rs:209:12
    |
 LL |     while -let 0 = 0 {}
    |            ^^^^^^^^^
@@ -644,72 +938,72 @@ LL |     while -let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:171:12
+  --> $DIR/disallowed-positions.rs:219:12
    |
 LL |     while (let 0 = 0)? {}
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:171:12
+  --> $DIR/disallowed-positions.rs:219:12
    |
 LL |     while (let 0 = 0)? {}
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:175:19
+  --> $DIR/disallowed-positions.rs:225:19
    |
 LL |     while true || let 0 = 0 {}
    |                   ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:175:16
+  --> $DIR/disallowed-positions.rs:225:16
    |
 LL |     while true || let 0 = 0 {}
    |                ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:176:20
+  --> $DIR/disallowed-positions.rs:228:20
    |
 LL |     while (true || let 0 = 0) {}
    |                    ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:176:17
+  --> $DIR/disallowed-positions.rs:228:17
    |
 LL |     while (true || let 0 = 0) {}
    |                 ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:177:28
+  --> $DIR/disallowed-positions.rs:231:28
    |
 LL |     while true && (true || let 0 = 0) {}
    |                            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:177:25
+  --> $DIR/disallowed-positions.rs:231:25
    |
 LL |     while true && (true || let 0 = 0) {}
    |                         ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:178:28
+  --> $DIR/disallowed-positions.rs:234:28
    |
 LL |     while true || (true && let 0 = 0) {}
    |                            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:178:20
+  --> $DIR/disallowed-positions.rs:234:20
    |
 LL |     while true || (true && let 0 = 0) {}
    |                    ^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:181:15
+  --> $DIR/disallowed-positions.rs:238:15
    |
 LL |     while x = let 0 = 0 {}
    |               ^^^^^^^^^
@@ -717,46 +1011,46 @@ LL |     while x = let 0 = 0 {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:184:18
+  --> $DIR/disallowed-positions.rs:243:18
    |
 LL |     while true..(let 0 = 0) {}
    |                  ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:184:18
+  --> $DIR/disallowed-positions.rs:243:18
    |
 LL |     while true..(let 0 = 0) {}
    |                  ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:186:14
+  --> $DIR/disallowed-positions.rs:247:14
    |
 LL |     while ..(let 0 = 0) {}
    |              ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:186:14
+  --> $DIR/disallowed-positions.rs:247:14
    |
 LL |     while ..(let 0 = 0) {}
    |              ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:188:12
+  --> $DIR/disallowed-positions.rs:251:12
    |
 LL |     while (let 0 = 0).. {}
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:188:12
+  --> $DIR/disallowed-positions.rs:251:12
    |
 LL |     while (let 0 = 0).. {}
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:192:11
+  --> $DIR/disallowed-positions.rs:257:11
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -764,7 +1058,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:196:11
+  --> $DIR/disallowed-positions.rs:261:11
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -772,7 +1066,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:203:11
+  --> $DIR/disallowed-positions.rs:268:11
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -780,7 +1074,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:211:11
+  --> $DIR/disallowed-positions.rs:276:11
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -788,7 +1082,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:217:22
+  --> $DIR/disallowed-positions.rs:282:22
    |
 LL |     while let true = let true = true {}
    |                      ^^^^^^^^^^^^^^^
@@ -796,7 +1090,7 @@ LL |     while let true = let true = true {}
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:232:6
+  --> $DIR/disallowed-positions.rs:298:6
    |
 LL |     &let 0 = 0;
    |      ^^^^^^^^^
@@ -804,7 +1098,7 @@ LL |     &let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:236:6
+  --> $DIR/disallowed-positions.rs:302:6
    |
 LL |     !let 0 = 0;
    |      ^^^^^^^^^
@@ -812,7 +1106,7 @@ LL |     !let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:239:6
+  --> $DIR/disallowed-positions.rs:305:6
    |
 LL |     *let 0 = 0;
    |      ^^^^^^^^^
@@ -820,7 +1114,7 @@ LL |     *let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:243:6
+  --> $DIR/disallowed-positions.rs:309:6
    |
 LL |     -let 0 = 0;
    |      ^^^^^^^^^
@@ -828,59 +1122,59 @@ LL |     -let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:253:6
+  --> $DIR/disallowed-positions.rs:319:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:253:6
+  --> $DIR/disallowed-positions.rs:319:6
    |
 LL |     (let 0 = 0)?;
    |      ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:259:13
+  --> $DIR/disallowed-positions.rs:325:13
    |
 LL |     true || let 0 = 0;
    |             ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:259:10
+  --> $DIR/disallowed-positions.rs:325:10
    |
 LL |     true || let 0 = 0;
    |          ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:262:14
+  --> $DIR/disallowed-positions.rs:328:14
    |
 LL |     (true || let 0 = 0);
    |              ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:262:11
+  --> $DIR/disallowed-positions.rs:328:11
    |
 LL |     (true || let 0 = 0);
    |           ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:265:22
+  --> $DIR/disallowed-positions.rs:331:22
    |
 LL |     true && (true || let 0 = 0);
    |                      ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `||` operators are not supported in let chain expressions
-  --> $DIR/disallowed-positions.rs:265:19
+  --> $DIR/disallowed-positions.rs:331:19
    |
 LL |     true && (true || let 0 = 0);
    |                   ^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:270:9
+  --> $DIR/disallowed-positions.rs:336:9
    |
 LL |     x = let 0 = 0;
    |         ^^^^^^^^^
@@ -888,46 +1182,46 @@ LL |     x = let 0 = 0;
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:274:12
+  --> $DIR/disallowed-positions.rs:340:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:274:12
+  --> $DIR/disallowed-positions.rs:340:12
    |
 LL |     true..(let 0 = 0);
    |            ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:277:8
+  --> $DIR/disallowed-positions.rs:343:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:277:8
+  --> $DIR/disallowed-positions.rs:343:8
    |
 LL |     ..(let 0 = 0);
    |        ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:280:6
+  --> $DIR/disallowed-positions.rs:346:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:280:6
+  --> $DIR/disallowed-positions.rs:346:6
    |
 LL |     (let 0 = 0)..;
    |      ^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:284:6
+  --> $DIR/disallowed-positions.rs:350:6
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -935,20 +1229,20 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:289:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     (let true = let true = true);
    |      ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:289:6
+  --> $DIR/disallowed-positions.rs:355:6
    |
 LL |     (let true = let true = true);
    |      ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:307:6
+  --> $DIR/disallowed-positions.rs:373:6
    |
 LL |     &let 0 = 0
    |      ^^^^^^^^^
@@ -956,7 +1250,7 @@ LL |     &let 0 = 0
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:319:17
+  --> $DIR/disallowed-positions.rs:385:17
    |
 LL |         true && let 1 = 1
    |                 ^^^^^^^^^
@@ -964,7 +1258,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:323:17
+  --> $DIR/disallowed-positions.rs:390:17
    |
 LL |         true && let 1 = 1
    |                 ^^^^^^^^^
@@ -972,7 +1266,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:327:17
+  --> $DIR/disallowed-positions.rs:395:17
    |
 LL |         true && let 1 = 1
    |                 ^^^^^^^^^
@@ -980,7 +1274,7 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:337:17
+  --> $DIR/disallowed-positions.rs:406:17
    |
 LL |         true && let 1 = 1
    |                 ^^^^^^^^^
@@ -988,124 +1282,124 @@ LL |         true && let 1 = 1
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:346:9
+  --> $DIR/disallowed-positions.rs:415:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:346:9
+  --> $DIR/disallowed-positions.rs:415:9
    |
 LL |     if (let Some(a) = opt && true) {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:350:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:350:9
+  --> $DIR/disallowed-positions.rs:420:9
    |
 LL |     if (let Some(a) = opt) && true {
    |         ^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:353:9
+  --> $DIR/disallowed-positions.rs:424:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:353:9
+  --> $DIR/disallowed-positions.rs:424:9
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |         ^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:353:32
+  --> $DIR/disallowed-positions.rs:424:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:353:32
+  --> $DIR/disallowed-positions.rs:424:32
    |
 LL |     if (let Some(a) = opt) && (let Some(b) = a) {
    |                                ^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:360:9
+  --> $DIR/disallowed-positions.rs:433:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:360:9
+  --> $DIR/disallowed-positions.rs:433:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:360:31
+  --> $DIR/disallowed-positions.rs:433:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:360:31
+  --> $DIR/disallowed-positions.rs:433:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && b == 1 {
    |                               ^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:364:9
+  --> $DIR/disallowed-positions.rs:439:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:364:9
+  --> $DIR/disallowed-positions.rs:439:9
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:364:31
+  --> $DIR/disallowed-positions.rs:439:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:364:31
+  --> $DIR/disallowed-positions.rs:439:31
    |
 LL |     if (let Some(a) = opt && (let Some(b) = a)) && true {
    |                               ^^^^^^^^^^^^^^^
 
 error: `let` expressions are not supported here
-  --> $DIR/disallowed-positions.rs:368:9
+  --> $DIR/disallowed-positions.rs:445:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 note: `let`s wrapped in parentheses are not supported in a context with let chains
-  --> $DIR/disallowed-positions.rs:368:9
+  --> $DIR/disallowed-positions.rs:445:9
    |
 LL |     if (let Some(a) = opt && (true)) && true {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:92:8
+  --> $DIR/disallowed-positions.rs:106:8
    |
 LL |     if &let 0 = 0 {}
    |        ^^^^^^^^^^ expected `bool`, found `&bool`
@@ -1117,19 +1411,19 @@ LL +     if let 0 = 0 {}
    |
 
 error[E0614]: type `bool` cannot be dereferenced
-  --> $DIR/disallowed-positions.rs:96:8
+  --> $DIR/disallowed-positions.rs:114:8
    |
 LL |     if *let 0 = 0 {}
    |        ^^^^^^^^^^
 
 error[E0600]: cannot apply unary operator `-` to type `bool`
-  --> $DIR/disallowed-positions.rs:98:8
+  --> $DIR/disallowed-positions.rs:118:8
    |
 LL |     if -let 0 = 0 {}
    |        ^^^^^^^^^^ cannot apply unary operator `-`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:106:8
+  --> $DIR/disallowed-positions.rs:128:8
    |
 LL |     if (let 0 = 0)? {}
    |        ^^^^^^^^^^^^ the `?` operator cannot be applied to type `bool`
@@ -1137,7 +1431,7 @@ LL |     if (let 0 = 0)? {}
    = help: the trait `Try` is not implemented for `bool`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
-  --> $DIR/disallowed-positions.rs:106:19
+  --> $DIR/disallowed-positions.rs:128:19
    |
 LL | / fn nested_within_if_expr() {
 LL | |     if &let 0 = 0 {}
@@ -1154,7 +1448,7 @@ LL | | }
    = help: the trait `FromResidual<_>` is not implemented for `()`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:116:8
+  --> $DIR/disallowed-positions.rs:147:8
    |
 LL |     if x = let 0 = 0 {}
    |        ^^^^^^^^^^^^^ expected `bool`, found `()`
@@ -1165,7 +1459,7 @@ LL |     if x == let 0 = 0 {}
    |          ~~
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:119:8
+  --> $DIR/disallowed-positions.rs:152:8
    |
 LL |     if true..(let 0 = 0) {}
    |        ^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1174,7 +1468,7 @@ LL |     if true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:121:8
+  --> $DIR/disallowed-positions.rs:156:8
    |
 LL |     if ..(let 0 = 0) {}
    |        ^^^^^^^^^^^^^ expected `bool`, found struct `RangeTo`
@@ -1183,7 +1477,7 @@ LL |     if ..(let 0 = 0) {}
             found struct `RangeTo<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:123:8
+  --> $DIR/disallowed-positions.rs:160:8
    |
 LL |     if (let 0 = 0).. {}
    |        ^^^^^^^^^^^^^ expected `bool`, found struct `RangeFrom`
@@ -1192,7 +1486,7 @@ LL |     if (let 0 = 0).. {}
             found struct `RangeFrom<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:127:12
+  --> $DIR/disallowed-positions.rs:166:12
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1203,7 +1497,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:127:8
+  --> $DIR/disallowed-positions.rs:166:8
    |
 LL |     if let Range { start: _, end: _ } = true..true && false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1212,7 +1506,7 @@ LL |     if let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:131:12
+  --> $DIR/disallowed-positions.rs:170:12
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1223,7 +1517,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:131:8
+  --> $DIR/disallowed-positions.rs:170:8
    |
 LL |     if let Range { start: _, end: _ } = true..true || false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1232,7 +1526,7 @@ LL |     if let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:138:12
+  --> $DIR/disallowed-positions.rs:177:12
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1243,20 +1537,20 @@ LL |     if let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:138:41
+  --> $DIR/disallowed-positions.rs:177:41
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |                                         ^^^^^^^ expected `bool`, found closure
    |
    = note: expected type `bool`
-           found closure `[closure@$DIR/disallowed-positions.rs:138:41: 138:48]`
+           found closure `[closure@$DIR/disallowed-positions.rs:177:41: 177:48]`
 help: use parentheses to call this closure
    |
 LL |     if let Range { start: F, end } = F..(|| true)() {}
    |                                         +       +++
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:138:8
+  --> $DIR/disallowed-positions.rs:177:8
    |
 LL |     if let Range { start: F, end } = F..|| true {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1265,7 +1559,7 @@ LL |     if let Range { start: F, end } = F..|| true {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:146:12
+  --> $DIR/disallowed-positions.rs:185:12
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1276,7 +1570,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:146:44
+  --> $DIR/disallowed-positions.rs:185:44
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |                                            ^^^^^^^ expected `bool`, found `&&bool`
@@ -1288,7 +1582,7 @@ LL +     if let Range { start: true, end } = t..false {}
    |
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:146:8
+  --> $DIR/disallowed-positions.rs:185:8
    |
 LL |     if let Range { start: true, end } = t..&&false {}
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1297,7 +1591,7 @@ LL |     if let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<bool>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:102:20
+  --> $DIR/disallowed-positions.rs:124:20
    |
 LL |         if let 0 = 0? {}
    |                    ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1305,7 +1599,7 @@ LL |         if let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:157:11
+  --> $DIR/disallowed-positions.rs:197:11
    |
 LL |     while &let 0 = 0 {}
    |           ^^^^^^^^^^ expected `bool`, found `&bool`
@@ -1317,19 +1611,19 @@ LL +     while let 0 = 0 {}
    |
 
 error[E0614]: type `bool` cannot be dereferenced
-  --> $DIR/disallowed-positions.rs:161:11
+  --> $DIR/disallowed-positions.rs:205:11
    |
 LL |     while *let 0 = 0 {}
    |           ^^^^^^^^^^
 
 error[E0600]: cannot apply unary operator `-` to type `bool`
-  --> $DIR/disallowed-positions.rs:163:11
+  --> $DIR/disallowed-positions.rs:209:11
    |
 LL |     while -let 0 = 0 {}
    |           ^^^^^^^^^^ cannot apply unary operator `-`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:171:11
+  --> $DIR/disallowed-positions.rs:219:11
    |
 LL |     while (let 0 = 0)? {}
    |           ^^^^^^^^^^^^ the `?` operator cannot be applied to type `bool`
@@ -1337,7 +1631,7 @@ LL |     while (let 0 = 0)? {}
    = help: the trait `Try` is not implemented for `bool`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
-  --> $DIR/disallowed-positions.rs:171:22
+  --> $DIR/disallowed-positions.rs:219:22
    |
 LL | / fn nested_within_while_expr() {
 LL | |     while &let 0 = 0 {}
@@ -1354,7 +1648,7 @@ LL | | }
    = help: the trait `FromResidual<_>` is not implemented for `()`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:181:11
+  --> $DIR/disallowed-positions.rs:238:11
    |
 LL |     while x = let 0 = 0 {}
    |           ^^^^^^^^^^^^^ expected `bool`, found `()`
@@ -1365,7 +1659,7 @@ LL |     while x == let 0 = 0 {}
    |             ~~
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:184:11
+  --> $DIR/disallowed-positions.rs:243:11
    |
 LL |     while true..(let 0 = 0) {}
    |           ^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1374,7 +1668,7 @@ LL |     while true..(let 0 = 0) {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:186:11
+  --> $DIR/disallowed-positions.rs:247:11
    |
 LL |     while ..(let 0 = 0) {}
    |           ^^^^^^^^^^^^^ expected `bool`, found struct `RangeTo`
@@ -1383,7 +1677,7 @@ LL |     while ..(let 0 = 0) {}
             found struct `RangeTo<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:188:11
+  --> $DIR/disallowed-positions.rs:251:11
    |
 LL |     while (let 0 = 0).. {}
    |           ^^^^^^^^^^^^^ expected `bool`, found struct `RangeFrom`
@@ -1392,7 +1686,7 @@ LL |     while (let 0 = 0).. {}
             found struct `RangeFrom<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:192:15
+  --> $DIR/disallowed-positions.rs:257:15
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1403,7 +1697,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:192:11
+  --> $DIR/disallowed-positions.rs:257:11
    |
 LL |     while let Range { start: _, end: _ } = true..true && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1412,7 +1706,7 @@ LL |     while let Range { start: _, end: _ } = true..true && false {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:196:15
+  --> $DIR/disallowed-positions.rs:261:15
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1423,7 +1717,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:196:11
+  --> $DIR/disallowed-positions.rs:261:11
    |
 LL |     while let Range { start: _, end: _ } = true..true || false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1432,7 +1726,7 @@ LL |     while let Range { start: _, end: _ } = true..true || false {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:203:15
+  --> $DIR/disallowed-positions.rs:268:15
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `fn() -> bool`
@@ -1443,20 +1737,20 @@ LL |     while let Range { start: F, end } = F..|| true {}
                   found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:203:44
+  --> $DIR/disallowed-positions.rs:268:44
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |                                            ^^^^^^^ expected `bool`, found closure
    |
    = note: expected type `bool`
-           found closure `[closure@$DIR/disallowed-positions.rs:203:44: 203:51]`
+           found closure `[closure@$DIR/disallowed-positions.rs:268:44: 268:51]`
 help: use parentheses to call this closure
    |
 LL |     while let Range { start: F, end } = F..(|| true)() {}
    |                                            +       +++
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:203:11
+  --> $DIR/disallowed-positions.rs:268:11
    |
 LL |     while let Range { start: F, end } = F..|| true {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1465,7 +1759,7 @@ LL |     while let Range { start: F, end } = F..|| true {}
             found struct `std::ops::Range<bool>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:211:15
+  --> $DIR/disallowed-positions.rs:276:15
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^   - this expression has type `&&bool`
@@ -1476,7 +1770,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:211:47
+  --> $DIR/disallowed-positions.rs:276:47
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |                                               ^^^^^^^ expected `bool`, found `&&bool`
@@ -1488,7 +1782,7 @@ LL +     while let Range { start: true, end } = t..false {}
    |
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:211:11
+  --> $DIR/disallowed-positions.rs:276:11
    |
 LL |     while let Range { start: true, end } = t..&&false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found struct `std::ops::Range`
@@ -1497,7 +1791,7 @@ LL |     while let Range { start: true, end } = t..&&false {}
             found struct `std::ops::Range<bool>`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:167:23
+  --> $DIR/disallowed-positions.rs:215:23
    |
 LL |         while let 0 = 0? {}
    |                       ^^ the `?` operator cannot be applied to type `{integer}`
@@ -1505,19 +1799,19 @@ LL |         while let 0 = 0? {}
    = help: the trait `Try` is not implemented for `{integer}`
 
 error[E0614]: type `bool` cannot be dereferenced
-  --> $DIR/disallowed-positions.rs:239:5
+  --> $DIR/disallowed-positions.rs:305:5
    |
 LL |     *let 0 = 0;
    |     ^^^^^^^^^^
 
 error[E0600]: cannot apply unary operator `-` to type `bool`
-  --> $DIR/disallowed-positions.rs:243:5
+  --> $DIR/disallowed-positions.rs:309:5
    |
 LL |     -let 0 = 0;
    |     ^^^^^^^^^^ cannot apply unary operator `-`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:253:5
+  --> $DIR/disallowed-positions.rs:319:5
    |
 LL |     (let 0 = 0)?;
    |     ^^^^^^^^^^^^ the `?` operator cannot be applied to type `bool`
@@ -1525,7 +1819,7 @@ LL |     (let 0 = 0)?;
    = help: the trait `Try` is not implemented for `bool`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
-  --> $DIR/disallowed-positions.rs:253:16
+  --> $DIR/disallowed-positions.rs:319:16
    |
 LL | / fn outside_if_and_while_expr() {
 LL | |     &let 0 = 0;
@@ -1542,7 +1836,7 @@ LL | | }
    = help: the trait `FromResidual<_>` is not implemented for `()`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:284:10
+  --> $DIR/disallowed-positions.rs:350:10
    |
 LL |     (let Range { start: _, end: _ } = true..true || false);
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^   ---- this expression has type `bool`
@@ -1553,7 +1847,7 @@ LL |     (let Range { start: _, end: _ } = true..true || false);
             found struct `std::ops::Range<_>`
 
 error[E0308]: mismatched types
-  --> $DIR/disallowed-positions.rs:307:5
+  --> $DIR/disallowed-positions.rs:373:5
    |
 LL | fn outside_if_and_while_expr() {
    |                                - help: try adding a return type: `-> &bool`
@@ -1562,14 +1856,14 @@ LL |     &let 0 = 0
    |     ^^^^^^^^^^ expected `()`, found `&bool`
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`
-  --> $DIR/disallowed-positions.rs:249:17
+  --> $DIR/disallowed-positions.rs:315:17
    |
 LL |         let 0 = 0?;
    |                 ^^ the `?` operator cannot be applied to type `{integer}`
    |
    = help: the trait `Try` is not implemented for `{integer}`
 
-error: aborting due to 156 previous errors
+error: aborting due to 205 previous errors
 
 Some errors have detailed explanations: E0277, E0308, E0600, E0614.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/rfc-2497-if-let-chains/feature-gate.rs b/src/test/ui/rfc-2497-if-let-chains/feature-gate.rs
index 8771821130848..2b407ef510c52 100644
--- a/src/test/ui/rfc-2497-if-let-chains/feature-gate.rs
+++ b/src/test/ui/rfc-2497-if-let-chains/feature-gate.rs
@@ -19,6 +19,11 @@ fn _if() {
 
     if let Range { start: _, end: _ } = (true..true) && false {}
     //~^ ERROR `let` expressions in this position are unstable [E0658]
+
+    if let 1 = 1 && let true = { true } && false {
+    //~^ ERROR `let` expressions in this position are unstable [E0658]
+    //~| ERROR `let` expressions in this position are unstable [E0658]
+    }
 }
 
 fn _while() {
diff --git a/src/test/ui/rfc-2497-if-let-chains/feature-gate.stderr b/src/test/ui/rfc-2497-if-let-chains/feature-gate.stderr
index bcea8bbaa730b..feea1c254d8da 100644
--- a/src/test/ui/rfc-2497-if-let-chains/feature-gate.stderr
+++ b/src/test/ui/rfc-2497-if-let-chains/feature-gate.stderr
@@ -1,17 +1,17 @@
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:50:20
+  --> $DIR/feature-gate.rs:55:20
    |
 LL |     #[cfg(FALSE)] (let 0 = 1);
    |                    ^^^
 
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:40:17
+  --> $DIR/feature-gate.rs:45:17
    |
 LL |     noop_expr!((let 0 = 1));
    |                 ^^^
 
 error: no rules expected the token `let`
-  --> $DIR/feature-gate.rs:53:15
+  --> $DIR/feature-gate.rs:58:15
    |
 LL |     macro_rules! use_expr {
    |     --------------------- when calling this macro
@@ -47,7 +47,25 @@ LL |     if let Range { start: _, end: _ } = (true..true) && false {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:27:19
+  --> $DIR/feature-gate.rs:23:8
+   |
+LL |     if let 1 = 1 && let true = { true } && false {
+   |        ^^^^^^^^^
+   |
+   = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
+   = help: add `#![feature(let_chains)]` to the crate attributes to enable
+
+error[E0658]: `let` expressions in this position are unstable
+  --> $DIR/feature-gate.rs:23:21
+   |
+LL |     if let 1 = 1 && let true = { true } && false {
+   |                     ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
+   = help: add `#![feature(let_chains)]` to the crate attributes to enable
+
+error[E0658]: `let` expressions in this position are unstable
+  --> $DIR/feature-gate.rs:32:19
    |
 LL |     while true && let 0 = 1 {}
    |                   ^^^^^^^^^
@@ -56,7 +74,7 @@ LL |     while true && let 0 = 1 {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:30:11
+  --> $DIR/feature-gate.rs:35:11
    |
 LL |     while let 0 = 1 && true {}
    |           ^^^^^^^^^
@@ -65,7 +83,7 @@ LL |     while let 0 = 1 && true {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:33:11
+  --> $DIR/feature-gate.rs:38:11
    |
 LL |     while let Range { start: _, end: _ } = (true..true) && false {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -74,7 +92,7 @@ LL |     while let Range { start: _, end: _ } = (true..true) && false {}
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:50:20
+  --> $DIR/feature-gate.rs:55:20
    |
 LL |     #[cfg(FALSE)] (let 0 = 1);
    |                    ^^^^^^^^^
@@ -83,7 +101,7 @@ LL |     #[cfg(FALSE)] (let 0 = 1);
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
 error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:40:17
+  --> $DIR/feature-gate.rs:45:17
    |
 LL |     noop_expr!((let 0 = 1));
    |                 ^^^^^^^^^
@@ -91,6 +109,6 @@ LL |     noop_expr!((let 0 = 1));
    = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
 
-error: aborting due to 11 previous errors
+error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.rs b/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.rs
index 6cc53a1935b95..a942d1f4cafbf 100644
--- a/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.rs
+++ b/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.rs
@@ -1,17 +1,45 @@
-// check-pass
-// known-bug
-
 #![feature(let_chains)]
 
 fn main() {
     let _opt = Some(1i32);
 
+    #[cfg(FALSE)]
+    {
+        let _ = &&let Some(x) = Some(42);
+        //~^ ERROR expected expression, found `let` statement
+    }
+    #[cfg(FALSE)]
+    {
+        if let Some(elem) = _opt && [1, 2, 3][let _ = &&let Some(x) = Some(42)] = 1 {
+        //~^ ERROR expected expression, found `let` statement
+        //~| ERROR expected expression, found `let` statement
+            true
+        }
+    }
+
     #[cfg(FALSE)]
     {
         if let Some(elem) = _opt && {
             [1, 2, 3][let _ = ()];
+            //~^ ERROR expected expression, found `let` statement
             true
         } {
         }
     }
+
+    #[cfg(FALSE)]
+    {
+        if let Some(elem) = _opt && [1, 2, 3][let _ = ()] = 1 {
+        //~^ ERROR expected expression, found `let` statement
+            true
+        }
+    }
+    #[cfg(FALSE)]
+    {
+        if let a = 1 && {
+            let x = let y = 1;
+            //~^ ERROR expected expression, found `let` statement
+        } {
+        }
+    }
 }
diff --git a/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.stderr b/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.stderr
new file mode 100644
index 0000000000000..d1ce83c723329
--- /dev/null
+++ b/src/test/ui/rfc-2497-if-let-chains/invalid-let-in-a-valid-let-context.stderr
@@ -0,0 +1,38 @@
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:8:19
+   |
+LL |         let _ = &&let Some(x) = Some(42);
+   |                   ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:13:47
+   |
+LL |         if let Some(elem) = _opt && [1, 2, 3][let _ = &&let Some(x) = Some(42)] = 1 {
+   |                                               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:13:57
+   |
+LL |         if let Some(elem) = _opt && [1, 2, 3][let _ = &&let Some(x) = Some(42)] = 1 {
+   |                                                         ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:23:23
+   |
+LL |             [1, 2, 3][let _ = ()];
+   |                       ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:32:47
+   |
+LL |         if let Some(elem) = _opt && [1, 2, 3][let _ = ()] = 1 {
+   |                                               ^^^
+
+error: expected expression, found `let` statement
+  --> $DIR/invalid-let-in-a-valid-let-context.rs:40:21
+   |
+LL |             let x = let y = 1;
+   |                     ^^^
+
+error: aborting due to 6 previous errors
+
diff --git a/src/test/ui/terminal-width/flag-human.rs b/src/test/ui/terminal-width/flag-human.rs
deleted file mode 100644
index e445a84fd012e..0000000000000
--- a/src/test/ui/terminal-width/flag-human.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-// compile-flags: -Z terminal-width=20
-
-// This test checks that `-Z terminal-width` effects the human error output by restricting it to an
-// arbitrarily low value so that the effect is visible.
-
-fn main() {
-    let _: () = 42;
-    //~^ ERROR mismatched types
-}
diff --git a/src/test/ui/terminal-width/flag-json.rs b/src/test/ui/terminal-width/flag-json.rs
deleted file mode 100644
index 3d2530e204b33..0000000000000
--- a/src/test/ui/terminal-width/flag-json.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-// compile-flags: -Z terminal-width=20 --error-format=json
-
-// This test checks that `-Z terminal-width` effects the JSON error output by restricting it to an
-// arbitrarily low value so that the effect is visible.
-
-fn main() {
-    let _: () = 42;
-    //~^ ERROR arguments to this function are incorrect
-}
diff --git a/src/tools/clippy/clippy_lints/src/misc.rs b/src/tools/clippy/clippy_lints/src/misc.rs
index df2430ced6b62..be7df08d89f05 100644
--- a/src/tools/clippy/clippy_lints/src/misc.rs
+++ b/src/tools/clippy/clippy_lints/src/misc.rs
@@ -301,7 +301,7 @@ fn in_attributes_expansion(expr: &Expr<'_>) -> bool {
     use rustc_span::hygiene::MacroKind;
     if expr.span.from_expansion() {
         let data = expr.span.ctxt().outer_expn_data();
-        matches!(data.kind, ExpnKind::Macro(MacroKind::Attr, _))
+        matches!(data.kind, ExpnKind::Macro(MacroKind::Attr|MacroKind::Derive, _))
     } else {
         false
     }
diff --git a/src/tools/clippy/tests/ui/used_underscore_binding.rs b/src/tools/clippy/tests/ui/used_underscore_binding.rs
index 21d66d5df79ec..d20977d55d29d 100644
--- a/src/tools/clippy/tests/ui/used_underscore_binding.rs
+++ b/src/tools/clippy/tests/ui/used_underscore_binding.rs
@@ -44,6 +44,12 @@ fn in_struct_field() {
     s._underscore_field += 1;
 }
 
+/// Tests that we do not lint if the struct field is used in code created with derive.
+#[derive(Clone, Debug)]
+pub struct UnderscoreInStruct {
+    _foo: u32,
+}
+
 /// Tests that we do not lint if the underscore is not a prefix
 fn non_prefix_underscore(some_foo: u32) -> u32 {
     some_foo + 1
diff --git a/src/tools/clippy/tests/ui/used_underscore_binding.stderr b/src/tools/clippy/tests/ui/used_underscore_binding.stderr
index 790b849210c9b..61a9161d212da 100644
--- a/src/tools/clippy/tests/ui/used_underscore_binding.stderr
+++ b/src/tools/clippy/tests/ui/used_underscore_binding.stderr
@@ -31,7 +31,7 @@ LL |     s._underscore_field += 1;
    |     ^^^^^^^^^^^^^^^^^^^
 
 error: used binding `_i` which is prefixed with an underscore. A leading underscore signals that a binding will not be used
-  --> $DIR/used_underscore_binding.rs:99:16
+  --> $DIR/used_underscore_binding.rs:105:16
    |
 LL |         uses_i(_i);
    |                ^^