Merging upstream version 1.66.0+dfsg1.

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

71 files changed, 2415 insertions, 4275 deletions

diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
index cca17a4ec..de916ea8c 100644
--- a/compiler/rustc_middle/Cargo.toml
+++ b/compiler/rustc_middle/Cargo.toml
@@ -12,8 +12,6 @@ chalk-ir = "0.80.0"
 either = "1.5.0"
 gsgdt = "0.1.2"
 polonius-engine = "0.13.0"
-rand = "0.8.4"
-rand_xoshiro = "0.6.0"
 rustc_apfloat = { path = "../rustc_apfloat" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
diff --git a/compiler/rustc_middle/benches/lib.rs b/compiler/rustc_middle/benches/lib.rs
deleted file mode 100644
index 237751bcb..000000000
--- a/compiler/rustc_middle/benches/lib.rs
+++ /dev/null
@@ -1,54 +0,0 @@
-#![feature(test)]
-
-extern crate test;
-
-use test::Bencher;
-
-// Static/dynamic method dispatch
-
-struct Struct {
-    field: isize,
-}
-
-trait Trait {
-    fn method(&self) -> isize;
-}
-
-impl Trait for Struct {
-    fn method(&self) -> isize {
-        self.field
-    }
-}
-
-#[bench]
-fn trait_vtable_method_call(b: &mut Bencher) {
-    let s = Struct { field: 10 };
-    let t = &s as &dyn Trait;
-    b.iter(|| t.method());
-}
-
-#[bench]
-fn trait_static_method_call(b: &mut Bencher) {
-    let s = Struct { field: 10 };
-    b.iter(|| s.method());
-}
-
-// Overhead of various match forms
-
-#[bench]
-fn option_some(b: &mut Bencher) {
-    let x = Some(10);
-    b.iter(|| match x {
-        Some(y) => y,
-        None => 11,
-    });
-}
-
-#[bench]
-fn vec_pattern(b: &mut Bencher) {
-    let x = [1, 2, 3, 4, 5, 6];
-    b.iter(|| match x {
-        [1, 2, 3, ..] => 10,
-        _ => 11,
-    });
-}
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 6bdf5a023..f8aae86fe 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -77,7 +77,7 @@ macro_rules! arena_types {
                     rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::ty::Ty<'tcx>>
                 >,
             [] all_traits: Vec<rustc_hir::def_id::DefId>,
-            [] privacy_access_levels: rustc_middle::middle::privacy::AccessLevels,
+            [] effective_visibilities: rustc_middle::middle::privacy::EffectiveVisibilities,
             [] foreign_module: rustc_session::cstore::ForeignModule,
             [] foreign_modules: Vec<rustc_session::cstore::ForeignModule>,
             [] upvars_mentioned: rustc_data_structures::fx::FxIndexMap<rustc_hir::HirId, rustc_hir::Upvar>,
@@ -96,13 +96,14 @@ macro_rules! arena_types {
             // since we need to allocate this type on both the `rustc_hir` arena
             // (during lowering) and the `librustc_middle` arena (for decoding MIR)
             [decode] asm_template: rustc_ast::InlineAsmTemplatePiece,
-            [decode] used_trait_imports: rustc_data_structures::fx::FxHashSet<rustc_hir::def_id::LocalDefId>,
+            [decode] used_trait_imports: rustc_data_structures::unord::UnordSet<rustc_hir::def_id::LocalDefId>,
             [decode] is_late_bound_map: rustc_data_structures::fx::FxIndexSet<rustc_hir::def_id::LocalDefId>,
             [decode] impl_source: rustc_middle::traits::ImplSource<'tcx, ()>,
 
             [] dep_kind: rustc_middle::dep_graph::DepKindStruct<'tcx>,
 
             [decode] trait_impl_trait_tys: rustc_data_structures::fx::FxHashMap<rustc_hir::def_id::DefId, rustc_middle::ty::Ty<'tcx>>,
+            [] bit_set_u32: rustc_index::bit_set::BitSet<u32>,
         ]);
     )
 }
diff --git a/compiler/rustc_middle/src/dep_graph/dep_node.rs b/compiler/rustc_middle/src/dep_graph/dep_node.rs
index 1fa0c6bab..6b5568269 100644
--- a/compiler/rustc_middle/src/dep_graph/dep_node.rs
+++ b/compiler/rustc_middle/src/dep_graph/dep_node.rs
@@ -62,86 +62,13 @@ use crate::ty::TyCtxt;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 use rustc_hir::definitions::DefPathHash;
-use rustc_hir::HirId;
+use rustc_hir::{HirId, ItemLocalId, OwnerId};
 use rustc_query_system::dep_graph::FingerprintStyle;
 use rustc_span::symbol::Symbol;
 use std::hash::Hash;
 
 pub use rustc_query_system::dep_graph::{DepContext, DepNodeParams};
 
-/// This struct stores metadata about each DepKind.
-///
-/// Information is retrieved by indexing the `DEP_KINDS` array using the integer value
-/// of the `DepKind`. Overall, this allows to implement `DepContext` using this manual
-/// jump table instead of large matches.
-pub struct DepKindStruct<'tcx> {
-    /// Anonymous queries cannot be replayed from one compiler invocation to the next.
-    /// When their result is needed, it is recomputed. They are useful for fine-grained
-    /// dependency tracking, and caching within one compiler invocation.
-    pub is_anon: bool,
-
-    /// Eval-always queries do not track their dependencies, and are always recomputed, even if
-    /// their inputs have not changed since the last compiler invocation. The result is still
-    /// cached within one compiler invocation.
-    pub is_eval_always: bool,
-
-    /// Whether the query key can be recovered from the hashed fingerprint.
-    /// See [DepNodeParams] trait for the behaviour of each key type.
-    pub fingerprint_style: FingerprintStyle,
-
-    /// The red/green evaluation system will try to mark a specific DepNode in the
-    /// dependency graph as green by recursively trying to mark the dependencies of
-    /// that `DepNode` as green. While doing so, it will sometimes encounter a `DepNode`
-    /// where we don't know if it is red or green and we therefore actually have
-    /// to recompute its value in order to find out. Since the only piece of
-    /// information that we have at that point is the `DepNode` we are trying to
-    /// re-evaluate, we need some way to re-run a query from just that. This is what
-    /// `force_from_dep_node()` implements.
-    ///
-    /// In the general case, a `DepNode` consists of a `DepKind` and an opaque
-    /// GUID/fingerprint that will uniquely identify the node. This GUID/fingerprint
-    /// is usually constructed by computing a stable hash of the query-key that the
-    /// `DepNode` corresponds to. Consequently, it is not in general possible to go
-    /// back from hash to query-key (since hash functions are not reversible). For
-    /// this reason `force_from_dep_node()` is expected to fail from time to time
-    /// because we just cannot find out, from the `DepNode` alone, what the
-    /// corresponding query-key is and therefore cannot re-run the query.
-    ///
-    /// The system deals with this case letting `try_mark_green` fail which forces
-    /// the root query to be re-evaluated.
-    ///
-    /// Now, if `force_from_dep_node()` would always fail, it would be pretty useless.
-    /// Fortunately, we can use some contextual information that will allow us to
-    /// reconstruct query-keys for certain kinds of `DepNode`s. In particular, we
-    /// enforce by construction that the GUID/fingerprint of certain `DepNode`s is a
-    /// valid `DefPathHash`. Since we also always build a huge table that maps every
-    /// `DefPathHash` in the current codebase to the corresponding `DefId`, we have
-    /// everything we need to re-run the query.
-    ///
-    /// Take the `mir_promoted` query as an example. Like many other queries, it
-    /// just has a single parameter: the `DefId` of the item it will compute the
-    /// validated MIR for. Now, when we call `force_from_dep_node()` on a `DepNode`
-    /// with kind `MirValidated`, we know that the GUID/fingerprint of the `DepNode`
-    /// is actually a `DefPathHash`, and can therefore just look up the corresponding
-    /// `DefId` in `tcx.def_path_hash_to_def_id`.
-    pub force_from_dep_node: Option<fn(tcx: TyCtxt<'tcx>, dep_node: DepNode) -> bool>,
-
-    /// Invoke a query to put the on-disk cached value in memory.
-    pub try_load_from_on_disk_cache: Option<fn(TyCtxt<'tcx>, DepNode)>,
-}
-
-impl DepKind {
-    #[inline(always)]
-    pub fn fingerprint_style(self, tcx: TyCtxt<'_>) -> FingerprintStyle {
-        // Only fetch the DepKindStruct once.
-        let data = tcx.query_kind(self);
-        if data.is_anon {
-            return FingerprintStyle::Opaque;
-        }
-        data.fingerprint_style
-    }
-}
-
 macro_rules! define_dep_nodes {
     (
      $($(#[$attr:meta])*
@@ -159,7 +86,7 @@ macro_rules! define_dep_nodes {
             $( $( #[$attr] )* $variant),*
         }
 
-        fn dep_kind_from_label_string(label: &str) -> Result<DepKind, ()> {
+        pub(super) fn dep_kind_from_label_string(label: &str) -> Result<DepKind, ()> {
             match label {
                 $(stringify!($variant) => Ok(DepKind::$variant),)*
                 _ => Err(()),
@@ -214,11 +141,6 @@ static_assert_size!(DepNode, 18);
 static_assert_size!(DepNode, 24);
 
 pub trait DepNodeExt: Sized {
-    /// Construct a DepNode from the given DepKind and DefPathHash. This
-    /// method will assert that the given DepKind actually requires a
-    /// single DefId/DefPathHash parameter.
-    fn from_def_path_hash(tcx: TyCtxt<'_>, def_path_hash: DefPathHash, kind: DepKind) -> Self;
-
     /// Extracts the DefId corresponding to this DepNode. This will work
     /// if two conditions are met:
     ///
@@ -243,14 +165,6 @@ pub trait DepNodeExt: Sized {
 }
 
 impl DepNodeExt for DepNode {
-    /// Construct a DepNode from the given DepKind and DefPathHash. This
-    /// method will assert that the given DepKind actually requires a
-    /// single DefId/DefPathHash parameter.
-    fn from_def_path_hash(tcx: TyCtxt<'_>, def_path_hash: DefPathHash, kind: DepKind) -> DepNode {
-        debug_assert!(kind.fingerprint_style(tcx) == FingerprintStyle::DefPathHash);
-        DepNode { kind, hash: def_path_hash.0.into() }
-    }
-
     /// Extracts the DefId corresponding to this DepNode. This will work
     /// if two conditions are met:
     ///
@@ -262,7 +176,7 @@ impl DepNodeExt for DepNode {
     /// refers to something from the previous compilation session that
     /// has been removed.
     fn extract_def_id<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Option<DefId> {
-        if self.kind.fingerprint_style(tcx) == FingerprintStyle::DefPathHash {
+        if tcx.fingerprint_style(self.kind) == FingerprintStyle::DefPathHash {
             Some(tcx.def_path_hash_to_def_id(DefPathHash(self.hash.into()), &mut || {
                 panic!("Failed to extract DefId: {:?} {}", self.kind, self.hash)
             }))
@@ -279,8 +193,8 @@ impl DepNodeExt for DepNode {
     ) -> Result<DepNode, ()> {
         let kind = dep_kind_from_label_string(label)?;
 
-        match kind.fingerprint_style(tcx) {
-            FingerprintStyle::Opaque => Err(()),
+        match tcx.fingerprint_style(kind) {
+            FingerprintStyle::Opaque | FingerprintStyle::HirId => Err(()),
             FingerprintStyle::Unit => Ok(DepNode::new_no_params(tcx, kind)),
             FingerprintStyle::DefPathHash => {
                 Ok(DepNode::from_def_path_hash(tcx, def_path_hash, kind))
@@ -355,6 +269,28 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for LocalDefId {
     }
 }
 
+impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for OwnerId {
+    #[inline(always)]
+    fn fingerprint_style() -> FingerprintStyle {
+        FingerprintStyle::DefPathHash
+    }
+
+    #[inline(always)]
+    fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint {
+        self.to_def_id().to_fingerprint(tcx)
+    }
+
+    #[inline(always)]
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
+        self.to_def_id().to_debug_str(tcx)
+    }
+
+    #[inline(always)]
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
+        dep_node.extract_def_id(tcx).map(|id| OwnerId { def_id: id.expect_local() })
+    }
+}
+
 impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for CrateNum {
     #[inline(always)]
     fn fingerprint_style() -> FingerprintStyle {
@@ -408,7 +344,7 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for (DefId, DefId) {
 impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for HirId {
     #[inline(always)]
     fn fingerprint_style() -> FingerprintStyle {
-        FingerprintStyle::Opaque
+        FingerprintStyle::HirId
     }
 
     // We actually would not need to specialize the implementation of this
@@ -417,10 +353,36 @@ impl<'tcx> DepNodeParams<TyCtxt<'tcx>> for HirId {
     #[inline(always)]
     fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint {
         let HirId { owner, local_id } = *self;
-
         let def_path_hash = tcx.def_path_hash(owner.to_def_id());
-        let local_id = Fingerprint::from_smaller_hash(local_id.as_u32().into());
+        Fingerprint::new(
+            // `owner` is local, so is completely defined by the local hash
+            def_path_hash.local_hash(),
+            local_id.as_u32().into(),
+        )
+    }
+
+    #[inline(always)]
+    fn to_debug_str(&self, tcx: TyCtxt<'tcx>) -> String {
+        let HirId { owner, local_id } = *self;
+        format!("{}.{}", tcx.def_path_str(owner.to_def_id()), local_id.as_u32())
+    }
 
-        def_path_hash.0.combine(local_id)
+    #[inline(always)]
+    fn recover(tcx: TyCtxt<'tcx>, dep_node: &DepNode) -> Option<Self> {
+        if tcx.fingerprint_style(dep_node.kind) == FingerprintStyle::HirId {
+            let (local_hash, local_id) = Fingerprint::from(dep_node.hash).as_value();
+            let def_path_hash = DefPathHash::new(tcx.sess.local_stable_crate_id(), local_hash);
+            let def_id = tcx
+                .def_path_hash_to_def_id(def_path_hash, &mut || {
+                    panic!("Failed to extract HirId: {:?} {}", dep_node.kind, dep_node.hash)
+                })
+                .expect_local();
+            let local_id = local_id
+                .try_into()
+                .unwrap_or_else(|_| panic!("local id should be u32, found {:?}", local_id));
+            Some(HirId { owner: OwnerId { def_id }, local_id: ItemLocalId::from_u32(local_id) })
+        } else {
+            None
+        }
     }
 }
diff --git a/compiler/rustc_middle/src/dep_graph/mod.rs b/compiler/rustc_middle/src/dep_graph/mod.rs
index c8b3b52b0..2e62bebc8 100644
--- a/compiler/rustc_middle/src/dep_graph/mod.rs
+++ b/compiler/rustc_middle/src/dep_graph/mod.rs
@@ -11,15 +11,17 @@ pub use rustc_query_system::dep_graph::{
     SerializedDepNodeIndex, WorkProduct, WorkProductId,
 };
 
-pub use dep_node::{label_strs, DepKind, DepKindStruct, DepNode, DepNodeExt};
+pub use dep_node::{label_strs, DepKind, DepNode, DepNodeExt};
 pub(crate) use dep_node::{make_compile_codegen_unit, make_compile_mono_item};
 
 pub type DepGraph = rustc_query_system::dep_graph::DepGraph<DepKind>;
+
 pub type TaskDeps = rustc_query_system::dep_graph::TaskDeps<DepKind>;
 pub type TaskDepsRef<'a> = rustc_query_system::dep_graph::TaskDepsRef<'a, DepKind>;
 pub type DepGraphQuery = rustc_query_system::dep_graph::DepGraphQuery<DepKind>;
 pub type SerializedDepGraph = rustc_query_system::dep_graph::SerializedDepGraph<DepKind>;
 pub type EdgeFilter = rustc_query_system::dep_graph::debug::EdgeFilter<DepKind>;
+pub type DepKindStruct<'tcx> = rustc_query_system::dep_graph::DepKindStruct<TyCtxt<'tcx>>;
 
 impl rustc_query_system::dep_graph::DepKind for DepKind {
     const NULL: Self = DepKind::Null;
@@ -91,50 +93,8 @@ impl<'tcx> DepContext for TyCtxt<'tcx> {
         self.sess
     }
 
-    #[inline(always)]
-    fn fingerprint_style(&self, kind: DepKind) -> rustc_query_system::dep_graph::FingerprintStyle {
-        kind.fingerprint_style(*self)
-    }
-
-    #[inline(always)]
-    fn is_eval_always(&self, kind: DepKind) -> bool {
-        self.query_kind(kind).is_eval_always
-    }
-
-    fn try_force_from_dep_node(&self, dep_node: DepNode) -> bool {
-        debug!("try_force_from_dep_node({:?}) --- trying to force", dep_node);
-
-        // We must avoid ever having to call `force_from_dep_node()` for a
-        // `DepNode::codegen_unit`:
-        // Since we cannot reconstruct the query key of a `DepNode::codegen_unit`, we
-        // would always end up having to evaluate the first caller of the
-        // `codegen_unit` query that *is* reconstructible. This might very well be
-        // the `compile_codegen_unit` query, thus re-codegenning the whole CGU just
-        // to re-trigger calling the `codegen_unit` query with the right key. At
-        // that point we would already have re-done all the work we are trying to
-        // avoid doing in the first place.
-        // The solution is simple: Just explicitly call the `codegen_unit` query for
-        // each CGU, right after partitioning. This way `try_mark_green` will always
-        // hit the cache instead of having to go through `force_from_dep_node`.
-        // This assertion makes sure, we actually keep applying the solution above.
-        debug_assert!(
-            dep_node.kind != DepKind::codegen_unit,
-            "calling force_from_dep_node() on DepKind::codegen_unit"
-        );
-
-        let cb = self.query_kind(dep_node.kind);
-        if let Some(f) = cb.force_from_dep_node {
-            f(*self, dep_node);
-            true
-        } else {
-            false
-        }
-    }
-
-    fn try_load_from_on_disk_cache(&self, dep_node: DepNode) {
-        let cb = self.query_kind(dep_node.kind);
-        if let Some(f) = cb.try_load_from_on_disk_cache {
-            f(*self, dep_node)
-        }
+    #[inline]
+    fn dep_kind_info(&self, dep_kind: DepKind) -> &DepKindStruct<'tcx> {
+        &self.query_kinds[dep_kind as usize]
     }
 }
diff --git a/compiler/rustc_middle/src/error.rs b/compiler/rustc_middle/src/error.rs
index 18b31a75b..a7a7ac059 100644
--- a/compiler/rustc_middle/src/error.rs
+++ b/compiler/rustc_middle/src/error.rs
@@ -1,10 +1,10 @@
-use rustc_macros::SessionDiagnostic;
+use rustc_macros::Diagnostic;
 use rustc_span::Span;
 
 use crate::ty::Ty;
 
-#[derive(SessionDiagnostic)]
-#[diag(middle::drop_check_overflow, code = "E0320")]
+#[derive(Diagnostic)]
+#[diag(middle_drop_check_overflow, code = "E0320")]
 #[note]
 pub struct DropCheckOverflow<'tcx> {
     #[primary_span]
@@ -13,8 +13,8 @@ pub struct DropCheckOverflow<'tcx> {
     pub overflow_ty: Ty<'tcx>,
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(middle::opaque_hidden_type_mismatch)]
+#[derive(Diagnostic)]
+#[diag(middle_opaque_hidden_type_mismatch)]
 pub struct OpaqueHiddenTypeMismatch<'tcx> {
     pub self_ty: Ty<'tcx>,
     pub other_ty: Ty<'tcx>,
@@ -25,22 +25,22 @@ pub struct OpaqueHiddenTypeMismatch<'tcx> {
     pub sub: TypeMismatchReason,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum TypeMismatchReason {
-    #[label(middle::conflict_types)]
+    #[label(middle_conflict_types)]
     ConflictType {
         #[primary_span]
         span: Span,
     },
-    #[note(middle::previous_use_here)]
+    #[note(middle_previous_use_here)]
     PreviousUse {
         #[primary_span]
         span: Span,
     },
 }
 
-#[derive(SessionDiagnostic)]
-#[diag(middle::limit_invalid)]
+#[derive(Diagnostic)]
+#[diag(middle_limit_invalid)]
 pub struct LimitInvalid<'a> {
     #[primary_span]
     pub span: Span,
@@ -48,3 +48,10 @@ pub struct LimitInvalid<'a> {
     pub value_span: Span,
     pub error_str: &'a str,
 }
+
+#[derive(Diagnostic)]
+#[diag(middle_const_eval_non_int)]
+pub struct ConstEvalNonIntError {
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 30a23c342..83a4d16d7 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -14,7 +14,7 @@ use rustc_index::vec::Idx;
 use rustc_middle::hir::nested_filter;
 use rustc_span::def_id::StableCrateId;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
 
 #[inline]
@@ -61,7 +61,7 @@ pub struct ParentHirIterator<'hir> {
 }
 
 impl<'hir> Iterator for ParentHirIterator<'hir> {
-    type Item = (HirId, Node<'hir>);
+    type Item = HirId;
 
     fn next(&mut self) -> Option<Self::Item> {
         if self.current_id == CRATE_HIR_ID {
@@ -77,10 +77,7 @@ impl<'hir> Iterator for ParentHirIterator<'hir> {
             }
 
             self.current_id = parent_id;
-            if let Some(node) = self.map.find(parent_id) {
-                return Some((parent_id, node));
-            }
-            // If this `HirId` doesn't have an entry, skip it and look for its `parent_id`.
+            return Some(parent_id);
         }
     }
 }
@@ -93,7 +90,7 @@ pub struct ParentOwnerIterator<'hir> {
 }
 
 impl<'hir> Iterator for ParentOwnerIterator<'hir> {
-    type Item = (LocalDefId, OwnerNode<'hir>);
+    type Item = (OwnerId, OwnerNode<'hir>);
 
     fn next(&mut self) -> Option<Self::Item> {
         if self.current_id.local_id.index() != 0 {
@@ -107,13 +104,13 @@ impl<'hir> Iterator for ParentOwnerIterator<'hir> {
         }
         loop {
             // There are nodes that do not have entries, so we need to skip them.
-            let parent_id = self.map.def_key(self.current_id.owner).parent;
+            let parent_id = self.map.def_key(self.current_id.owner.def_id).parent;
 
-            let parent_id = parent_id.map_or(CRATE_HIR_ID.owner, |local_def_index| {
+            let parent_id = parent_id.map_or(CRATE_OWNER_ID, |local_def_index| {
                 let def_id = LocalDefId { local_def_index };
                 self.map.local_def_id_to_hir_id(def_id).owner
             });
-            self.current_id = HirId::make_owner(parent_id);
+            self.current_id = HirId::make_owner(parent_id.def_id);
 
             // If this `HirId` doesn't have an entry, skip it and look for its `parent_id`.
             if let Some(node) = self.map.tcx.hir_owner(self.current_id.owner) {
@@ -131,7 +128,7 @@ impl<'hir> Map<'hir> {
 
     #[inline]
     pub fn root_module(self) -> &'hir Mod<'hir> {
-        match self.tcx.hir_owner(CRATE_DEF_ID).map(|o| o.node) {
+        match self.tcx.hir_owner(CRATE_OWNER_ID).map(|o| o.node) {
             Some(OwnerNode::Crate(item)) => item,
             _ => bug!(),
         }
@@ -186,7 +183,7 @@ impl<'hir> Map<'hir> {
     #[inline]
     pub fn opt_local_def_id(self, hir_id: HirId) -> Option<LocalDefId> {
         if hir_id.local_id == ItemLocalId::new(0) {
-            Some(hir_id.owner)
+            Some(hir_id.owner.def_id)
         } else {
             self.tcx
                 .hir_owner_nodes(hir_id.owner)
@@ -244,7 +241,7 @@ impl<'hir> Map<'hir> {
             Node::ImplItem(item) => match item.kind {
                 ImplItemKind::Const(..) => DefKind::AssocConst,
                 ImplItemKind::Fn(..) => DefKind::AssocFn,
-                ImplItemKind::TyAlias(..) => DefKind::AssocTy,
+                ImplItemKind::Type(..) => DefKind::AssocTy,
             },
             Node::Variant(_) => DefKind::Variant,
             Node::Ctor(variant_data) => {
@@ -352,24 +349,24 @@ impl<'hir> Map<'hir> {
     }
 
     pub fn get_generics(self, id: LocalDefId) -> Option<&'hir Generics<'hir>> {
-        let node = self.tcx.hir_owner(id)?;
+        let node = self.tcx.hir_owner(OwnerId { def_id: id })?;
         node.node.generics()
     }
 
     pub fn item(self, id: ItemId) -> &'hir Item<'hir> {
-        self.tcx.hir_owner(id.def_id).unwrap().node.expect_item()
+        self.tcx.hir_owner(id.owner_id).unwrap().node.expect_item()
     }
 
     pub fn trait_item(self, id: TraitItemId) -> &'hir TraitItem<'hir> {
-        self.tcx.hir_owner(id.def_id).unwrap().node.expect_trait_item()
+        self.tcx.hir_owner(id.owner_id).unwrap().node.expect_trait_item()
     }
 
     pub fn impl_item(self, id: ImplItemId) -> &'hir ImplItem<'hir> {
-        self.tcx.hir_owner(id.def_id).unwrap().node.expect_impl_item()
+        self.tcx.hir_owner(id.owner_id).unwrap().node.expect_impl_item()
     }
 
     pub fn foreign_item(self, id: ForeignItemId) -> &'hir ForeignItem<'hir> {
-        self.tcx.hir_owner(id.def_id).unwrap().node.expect_foreign_item()
+        self.tcx.hir_owner(id.owner_id).unwrap().node.expect_foreign_item()
     }
 
     pub fn body(self, id: BodyId) -> &'hir Body<'hir> {
@@ -393,8 +390,8 @@ impl<'hir> Map<'hir> {
     }
 
     pub fn enclosing_body_owner(self, hir_id: HirId) -> LocalDefId {
-        for (parent, _) in self.parent_iter(hir_id) {
-            if let Some(body) = self.find(parent).map(associated_body).flatten() {
+        for (_, node) in self.parent_iter(hir_id) {
+            if let Some(body) = associated_body(node) {
                 return self.body_owner_def_id(body);
             }
         }
@@ -532,7 +529,7 @@ impl<'hir> Map<'hir> {
 
     pub fn get_module(self, module: LocalDefId) -> (&'hir Mod<'hir>, Span, HirId) {
         let hir_id = HirId::make_owner(module);
-        match self.tcx.hir_owner(module).map(|o| o.node) {
+        match self.tcx.hir_owner(hir_id.owner).map(|o| o.node) {
             Some(OwnerNode::Item(&Item { span, kind: ItemKind::Mod(ref m), .. })) => {
                 (m, span, hir_id)
             }
@@ -622,26 +619,33 @@ impl<'hir> Map<'hir> {
     pub fn for_each_module(self, mut f: impl FnMut(LocalDefId)) {
         let crate_items = self.tcx.hir_crate_items(());
         for module in crate_items.submodules.iter() {
-            f(*module)
+            f(module.def_id)
         }
     }
 
     #[inline]
     pub fn par_for_each_module(self, f: impl Fn(LocalDefId) + Sync + Send) {
         let crate_items = self.tcx.hir_crate_items(());
-        par_for_each_in(&crate_items.submodules[..], |module| f(*module))
+        par_for_each_in(&crate_items.submodules[..], |module| f(module.def_id))
     }
 
     /// Returns an iterator for the nodes in the ancestor tree of the `current_id`
     /// until the crate root is reached. Prefer this over your own loop using `get_parent_node`.
     #[inline]
-    pub fn parent_iter(self, current_id: HirId) -> ParentHirIterator<'hir> {
+    pub fn parent_id_iter(self, current_id: HirId) -> impl Iterator<Item = HirId> + 'hir {
         ParentHirIterator { current_id, map: self }
     }
 
     /// Returns an iterator for the nodes in the ancestor tree of the `current_id`
     /// until the crate root is reached. Prefer this over your own loop using `get_parent_node`.
     #[inline]
+    pub fn parent_iter(self, current_id: HirId) -> impl Iterator<Item = (HirId, Node<'hir>)> {
+        self.parent_id_iter(current_id).filter_map(move |id| Some((id, self.find(id)?)))
+    }
+
+    /// Returns an iterator for the nodes in the ancestor tree of the `current_id`
+    /// until the crate root is reached. Prefer this over your own loop using `get_parent_node`.
+    #[inline]
     pub fn parent_owner_iter(self, current_id: HirId) -> ParentOwnerIterator<'hir> {
         ParentOwnerIterator { current_id, map: self }
     }
@@ -721,27 +725,27 @@ impl<'hir> Map<'hir> {
         None
     }
 
-    /// Retrieves the `HirId` for `id`'s parent item, or `id` itself if no
+    /// Retrieves the `OwnerId` for `id`'s parent item, or `id` itself if no
     /// parent item is in this map. The "parent item" is the closest parent node
     /// in the HIR which is recorded by the map and is an item, either an item
     /// in a module, trait, or impl.
-    pub fn get_parent_item(self, hir_id: HirId) -> LocalDefId {
+    pub fn get_parent_item(self, hir_id: HirId) -> OwnerId {
         if let Some((def_id, _node)) = self.parent_owner_iter(hir_id).next() {
             def_id
         } else {
-            CRATE_DEF_ID
+            CRATE_OWNER_ID
         }
     }
 
-    /// Returns the `HirId` of `id`'s nearest module parent, or `id` itself if no
+    /// Returns the `OwnerId` of `id`'s nearest module parent, or `id` itself if no
     /// module parent is in this map.
-    pub(super) fn get_module_parent_node(self, hir_id: HirId) -> LocalDefId {
+    pub(super) fn get_module_parent_node(self, hir_id: HirId) -> OwnerId {
         for (def_id, node) in self.parent_owner_iter(hir_id) {
             if let OwnerNode::Item(&Item { kind: ItemKind::Mod(_), .. }) = node {
                 return def_id;
             }
         }
-        CRATE_DEF_ID
+        CRATE_OWNER_ID
     }
 
     /// When on an if expression, a match arm tail expression or a match arm, give back
@@ -814,30 +818,30 @@ impl<'hir> Map<'hir> {
         }
         bug!(
             "expected foreign mod or inlined parent, found {}",
-            self.node_to_string(HirId::make_owner(parent))
+            self.node_to_string(HirId::make_owner(parent.def_id))
         )
     }
 
-    pub fn expect_owner(self, id: LocalDefId) -> OwnerNode<'hir> {
+    pub fn expect_owner(self, id: OwnerId) -> OwnerNode<'hir> {
         self.tcx.hir_owner(id).unwrap_or_else(|| bug!("expected owner for {:?}", id)).node
     }
 
     pub fn expect_item(self, id: LocalDefId) -> &'hir Item<'hir> {
-        match self.tcx.hir_owner(id) {
+        match self.tcx.hir_owner(OwnerId { def_id: id }) {
             Some(Owner { node: OwnerNode::Item(item), .. }) => item,
             _ => bug!("expected item, found {}", self.node_to_string(HirId::make_owner(id))),
         }
     }
 
     pub fn expect_impl_item(self, id: LocalDefId) -> &'hir ImplItem<'hir> {
-        match self.tcx.hir_owner(id) {
+        match self.tcx.hir_owner(OwnerId { def_id: id }) {
             Some(Owner { node: OwnerNode::ImplItem(item), .. }) => item,
             _ => bug!("expected impl item, found {}", self.node_to_string(HirId::make_owner(id))),
         }
     }
 
     pub fn expect_trait_item(self, id: LocalDefId) -> &'hir TraitItem<'hir> {
-        match self.tcx.hir_owner(id) {
+        match self.tcx.hir_owner(OwnerId { def_id: id }) {
             Some(Owner { node: OwnerNode::TraitItem(item), .. }) => item,
             _ => bug!("expected trait item, found {}", self.node_to_string(HirId::make_owner(id))),
         }
@@ -850,11 +854,14 @@ impl<'hir> Map<'hir> {
         }
     }
 
-    pub fn expect_foreign_item(self, id: LocalDefId) -> &'hir ForeignItem<'hir> {
+    pub fn expect_foreign_item(self, id: OwnerId) -> &'hir ForeignItem<'hir> {
         match self.tcx.hir_owner(id) {
             Some(Owner { node: OwnerNode::ForeignItem(item), .. }) => item,
             _ => {
-                bug!("expected foreign item, found {}", self.node_to_string(HirId::make_owner(id)))
+                bug!(
+                    "expected foreign item, found {}",
+                    self.node_to_string(HirId::make_owner(id.def_id))
+                )
             }
         }
     }
@@ -934,9 +941,19 @@ impl<'hir> Map<'hir> {
 
         let span = match self.find(hir_id)? {
             // Function-like.
-            Node::Item(Item { kind: ItemKind::Fn(sig, ..), .. })
-            | Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(sig, ..), .. })
-            | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(sig, ..), .. }) => sig.span,
+            Node::Item(Item { kind: ItemKind::Fn(sig, ..), span: outer_span, .. })
+            | Node::TraitItem(TraitItem {
+                kind: TraitItemKind::Fn(sig, ..),
+                span: outer_span,
+                ..
+            })
+            | Node::ImplItem(ImplItem {
+                kind: ImplItemKind::Fn(sig, ..), span: outer_span, ..
+            }) => {
+                // Ensure that the returned span has the item's SyntaxContext, and not the
+                // SyntaxContext of the visibility.
+                sig.span.find_ancestor_in_same_ctxt(*outer_span).unwrap_or(*outer_span)
+            }
             // Constants and Statics.
             Node::Item(Item {
                 kind:
@@ -978,7 +995,11 @@ impl<'hir> Map<'hir> {
             }
             // Other cases.
             Node::Item(item) => match &item.kind {
-                ItemKind::Use(path, _) => path.span,
+                ItemKind::Use(path, _) => {
+                    // Ensure that the returned span has the item's SyntaxContext, and not the
+                    // SyntaxContext of the path.
+                    path.span.find_ancestor_in_same_ctxt(item.span).unwrap_or(item.span)
+                }
                 _ => named_span(item.span, item.ident, item.kind.generics()),
             },
             Node::Variant(variant) => named_span(variant.span, variant.ident, None),
@@ -988,11 +1009,17 @@ impl<'hir> Map<'hir> {
                 _ => named_span(item.span, item.ident, None),
             },
             Node::Ctor(_) => return self.opt_span(self.get_parent_node(hir_id)),
-            Node::Expr(Expr { kind: ExprKind::Closure(Closure { fn_decl_span, .. }), .. }) => {
-                *fn_decl_span
+            Node::Expr(Expr {
+                kind: ExprKind::Closure(Closure { fn_decl_span, .. }),
+                span,
+                ..
+            }) => {
+                // Ensure that the returned span has the item's SyntaxContext.
+                fn_decl_span.find_ancestor_in_same_ctxt(*span).unwrap_or(*span)
             }
             _ => self.span_with_body(hir_id),
         };
+        debug_assert_eq!(span.ctxt(), self.span_with_body(hir_id).ctxt());
         Some(span)
     }
 
@@ -1128,7 +1155,7 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
                 .filter_map(|(def_id, info)| {
                     let _ = info.as_owner()?;
                     let def_path_hash = definitions.def_path_hash(def_id);
-                    let span = resolutions.source_span[def_id];
+                    let span = resolutions.source_span.get(def_id).unwrap_or(&DUMMY_SP);
                     debug_assert_eq!(span.parent(), None);
                     Some((def_path_hash, span))
                 })
@@ -1217,7 +1244,7 @@ fn hir_id_to_string(map: Map<'_>, id: HirId) -> String {
                 format!("assoc const {} in {}{}", ii.ident, path_str(), id_str)
             }
             ImplItemKind::Fn(..) => format!("method {} in {}{}", ii.ident, path_str(), id_str),
-            ImplItemKind::TyAlias(_) => {
+            ImplItemKind::Type(_) => {
                 format!("assoc type {} in {}{}", ii.ident, path_str(), id_str)
             }
         },
@@ -1290,7 +1317,7 @@ pub(crate) fn hir_crate_items(tcx: TyCtxt<'_>, _: ()) -> ModuleItems {
     // A "crate collector" and "module collector" start at a
     // module item (the former starts at the crate root) but only
     // the former needs to collect it. ItemCollector does not do this for us.
-    collector.submodules.push(CRATE_DEF_ID);
+    collector.submodules.push(CRATE_OWNER_ID);
     tcx.hir().walk_toplevel_module(&mut collector);
 
     let ItemCollector {
@@ -1318,7 +1345,7 @@ struct ItemCollector<'tcx> {
     // otherwise it collects items in some module.
     crate_collector: bool,
     tcx: TyCtxt<'tcx>,
-    submodules: Vec<LocalDefId>,
+    submodules: Vec<OwnerId>,
     items: Vec<ItemId>,
     trait_items: Vec<TraitItemId>,
     impl_items: Vec<ImplItemId>,
@@ -1350,14 +1377,14 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
 
     fn visit_item(&mut self, item: &'hir Item<'hir>) {
         if associated_body(Node::Item(item)).is_some() {
-            self.body_owners.push(item.def_id);
+            self.body_owners.push(item.owner_id.def_id);
         }
 
         self.items.push(item.item_id());
 
         // Items that are modules are handled here instead of in visit_mod.
         if let ItemKind::Mod(module) = &item.kind {
-            self.submodules.push(item.def_id);
+            self.submodules.push(item.owner_id);
             // A module collector does not recurse inside nested modules.
             if self.crate_collector {
                 intravisit::walk_mod(self, module, item.hir_id());
@@ -1386,7 +1413,7 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
 
     fn visit_trait_item(&mut self, item: &'hir TraitItem<'hir>) {
         if associated_body(Node::TraitItem(item)).is_some() {
-            self.body_owners.push(item.def_id);
+            self.body_owners.push(item.owner_id.def_id);
         }
 
         self.trait_items.push(item.trait_item_id());
@@ -1395,7 +1422,7 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
 
     fn visit_impl_item(&mut self, item: &'hir ImplItem<'hir>) {
         if associated_body(Node::ImplItem(item)).is_some() {
-            self.body_owners.push(item.def_id);
+            self.body_owners.push(item.owner_id.def_id);
         }
 
         self.impl_items.push(item.impl_item_id());
diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index 211a61471..1c6264ad0 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -39,7 +39,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Owner<'tcx> {
 /// bodies.  The Ids are in visitor order.  This is used to partition a pass between modules.
 #[derive(Debug, HashStable, Encodable, Decodable)]
 pub struct ModuleItems {
-    submodules: Box<[LocalDefId]>,
+    submodules: Box<[OwnerId]>,
     items: Box<[ItemId]>,
     trait_items: Box<[TraitItemId]>,
     impl_items: Box<[ImplItemId]>,
@@ -67,10 +67,10 @@ impl ModuleItems {
     pub fn definitions(&self) -> impl Iterator<Item = LocalDefId> + '_ {
         self.items
             .iter()
-            .map(|id| id.def_id)
-            .chain(self.trait_items.iter().map(|id| id.def_id))
-            .chain(self.impl_items.iter().map(|id| id.def_id))
-            .chain(self.foreign_items.iter().map(|id| id.def_id))
+            .map(|id| id.owner_id.def_id)
+            .chain(self.trait_items.iter().map(|id| id.owner_id.def_id))
+            .chain(self.impl_items.iter().map(|id| id.owner_id.def_id))
+            .chain(self.foreign_items.iter().map(|id| id.owner_id.def_id))
     }
 
     pub fn par_items(&self, f: impl Fn(ItemId) + Send + Sync) {
@@ -97,7 +97,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn parent_module(self, id: HirId) -> LocalDefId {
-        self.parent_module_from_def_id(id.owner)
+        self.parent_module_from_def_id(id.owner.def_id)
     }
 
     pub fn impl_subject(self, def_id: DefId) -> ImplSubject<'tcx> {
@@ -110,13 +110,13 @@ impl<'tcx> TyCtxt<'tcx> {
 pub fn provide(providers: &mut Providers) {
     providers.parent_module_from_def_id = |tcx, id| {
         let hir = tcx.hir();
-        hir.get_module_parent_node(hir.local_def_id_to_hir_id(id))
+        hir.get_module_parent_node(hir.local_def_id_to_hir_id(id)).def_id
     };
     providers.hir_crate_items = map::hir_crate_items;
     providers.crate_hash = map::crate_hash;
     providers.hir_module_items = map::hir_module_items;
     providers.hir_owner = |tcx, id| {
-        let owner = tcx.hir_crate(()).owners.get(id)?.as_owner()?;
+        let owner = tcx.hir_crate(()).owners.get(id.def_id)?.as_owner()?;
         let node = owner.node();
         Some(Owner { node, hash_without_bodies: owner.nodes.hash_without_bodies })
     };
@@ -128,21 +128,24 @@ pub fn provide(providers: &mut Providers) {
             MaybeOwner::NonOwner(hir_id) => hir_id,
         }
     };
-    providers.hir_owner_nodes = |tcx, id| tcx.hir_crate(()).owners[id].map(|i| &i.nodes);
+    providers.hir_owner_nodes = |tcx, id| tcx.hir_crate(()).owners[id.def_id].map(|i| &i.nodes);
     providers.hir_owner_parent = |tcx, id| {
         // Accessing the local_parent is ok since its value is hashed as part of `id`'s DefPathHash.
-        tcx.opt_local_parent(id).map_or(CRATE_HIR_ID, |parent| {
+        tcx.opt_local_parent(id.def_id).map_or(CRATE_HIR_ID, |parent| {
             let mut parent_hir_id = tcx.hir().local_def_id_to_hir_id(parent);
-            if let Some(local_id) =
-                tcx.hir_crate(()).owners[parent_hir_id.owner].unwrap().parenting.get(&id)
+            if let Some(local_id) = tcx.hir_crate(()).owners[parent_hir_id.owner.def_id]
+                .unwrap()
+                .parenting
+                .get(&id.def_id)
             {
                 parent_hir_id.local_id = *local_id;
             }
             parent_hir_id
         })
     };
-    providers.hir_attrs =
-        |tcx, id| tcx.hir_crate(()).owners[id].as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs);
+    providers.hir_attrs = |tcx, id| {
+        tcx.hir_crate(()).owners[id.def_id].as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs)
+    };
     providers.source_span =
         |tcx, def_id| tcx.resolutions(()).source_span.get(def_id).copied().unwrap_or(DUMMY_SP);
     providers.def_span = |tcx, def_id| {
@@ -177,6 +180,7 @@ pub fn provide(providers: &mut Providers) {
         let id = id.expect_local();
         tcx.resolutions(()).expn_that_defined.get(&id).copied().unwrap_or(ExpnId::root())
     };
-    providers.in_scope_traits_map =
-        |tcx, id| tcx.hir_crate(()).owners[id].as_owner().map(|owner_info| &owner_info.trait_map);
+    providers.in_scope_traits_map = |tcx, id| {
+        tcx.hir_crate(()).owners[id.def_id].as_owner().map(|owner_info| &owner_info.trait_map)
+    };
 }
diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs
index f2627885d..41d8c7ffd 100644
--- a/compiler/rustc_middle/src/infer/unify_key.rs
+++ b/compiler/rustc_middle/src/infer/unify_key.rs
@@ -129,7 +129,7 @@ impl<'tcx> UnifyKey for ty::ConstVid<'tcx> {
 }
 
 impl<'tcx> UnifyValue for ConstVarValue<'tcx> {
-    type Error = (ty::Const<'tcx>, ty::Const<'tcx>);
+    type Error = NoError;
 
     fn unify_values(&value1: &Self, &value2: &Self) -> Result<Self, Self::Error> {
         Ok(match (value1.val, value2.val) {
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 01b9277b9..a58cbc376 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -31,22 +31,19 @@
 #![feature(discriminant_kind)]
 #![feature(exhaustive_patterns)]
 #![feature(get_mut_unchecked)]
-#![cfg_attr(bootstrap, feature(generic_associated_types))]
 #![feature(if_let_guard)]
-#![feature(map_first_last)]
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(extern_types)]
 #![feature(new_uninit)]
 #![feature(once_cell)]
 #![feature(let_chains)]
-#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(min_specialization)]
 #![feature(trusted_len)]
 #![feature(type_alias_impl_trait)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
-#![feature(half_open_range_patterns)]
+#![cfg_attr(bootstrap, feature(half_open_range_patterns))]
 #![feature(control_flow_enum)]
 #![feature(associated_type_defaults)]
 #![feature(trusted_step)]
@@ -58,6 +55,7 @@
 #![feature(drain_filter)]
 #![feature(intra_doc_pointers)]
 #![feature(yeet_expr)]
+#![feature(result_option_inspect)]
 #![feature(const_option)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 2f45222de..79522bd0b 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -1,20 +1,20 @@
 use std::cmp;
 
 use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_errors::{Diagnostic, DiagnosticId, LintDiagnosticBuilder, MultiSpan};
-use rustc_hir::HirId;
-use rustc_index::vec::IndexVec;
-use rustc_query_system::ich::StableHashingContext;
+use rustc_data_structures::sorted_map::SortedMap;
+use rustc_errors::{Diagnostic, DiagnosticBuilder, DiagnosticId, DiagnosticMessage, MultiSpan};
+use rustc_hir::{HirId, ItemLocalId};
 use rustc_session::lint::{
     builtin::{self, FORBIDDEN_LINT_GROUPS},
-    FutureIncompatibilityReason, Level, Lint, LintExpectationId, LintId,
+    FutureIncompatibilityReason, Level, Lint, LintId,
 };
 use rustc_session::Session;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::{DesugaringKind, ExpnKind};
 use rustc_span::{symbol, Span, Symbol, DUMMY_SP};
 
+use crate::ty::TyCtxt;
+
 /// How a lint level was set.
 #[derive(Clone, Copy, PartialEq, Eq, HashStable, Debug)]
 pub enum LintLevelSource {
@@ -23,7 +23,12 @@ pub enum LintLevelSource {
     Default,
 
     /// Lint level was set by an attribute.
-    Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */),
+    Node {
+        name: Symbol,
+        span: Span,
+        /// RFC 2383 reason
+        reason: Option<Symbol>,
+    },
 
     /// Lint level was set by a command-line flag.
     /// The provided `Level` is the level specified on the command line.
@@ -35,7 +40,7 @@ impl LintLevelSource {
     pub fn name(&self) -> Symbol {
         match *self {
             LintLevelSource::Default => symbol::kw::Default,
-            LintLevelSource::Node(name, _, _) => name,
+            LintLevelSource::Node { name, .. } => name,
             LintLevelSource::CommandLine(name, _) => name,
         }
     }
@@ -43,7 +48,7 @@ impl LintLevelSource {
     pub fn span(&self) -> Span {
         match *self {
             LintLevelSource::Default => DUMMY_SP,
-            LintLevelSource::Node(_, span, _) => span,
+            LintLevelSource::Node { span, .. } => span,
             LintLevelSource::CommandLine(_, _) => DUMMY_SP,
         }
     }
@@ -52,145 +57,137 @@ impl LintLevelSource {
 /// A tuple of a lint level and its source.
 pub type LevelAndSource = (Level, LintLevelSource);
 
-#[derive(Debug, HashStable)]
-pub struct LintLevelSets {
-    pub list: IndexVec<LintStackIndex, LintSet>,
-    pub lint_cap: Level,
-}
-
-rustc_index::newtype_index! {
-    #[derive(HashStable)]
-    pub struct LintStackIndex {
-        const COMMAND_LINE = 0,
-    }
-}
-
-#[derive(Debug, HashStable)]
-pub struct LintSet {
-    // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
-    // flag.
-    pub specs: FxHashMap<LintId, LevelAndSource>,
-
-    pub parent: LintStackIndex,
+/// Return type for the `shallow_lint_levels_on` query.
+///
+/// This map represents the set of allowed lints and allowance levels given
+/// by the attributes for *a single HirId*.
+#[derive(Default, Debug, HashStable)]
+pub struct ShallowLintLevelMap {
+    pub specs: SortedMap<ItemLocalId, FxHashMap<LintId, LevelAndSource>>,
 }
 
-impl LintLevelSets {
-    pub fn new() -> Self {
-        LintLevelSets { list: IndexVec::new(), lint_cap: Level::Forbid }
-    }
-
-    pub fn get_lint_level(
-        &self,
-        lint: &'static Lint,
-        idx: LintStackIndex,
-        aux: Option<&FxHashMap<LintId, LevelAndSource>>,
-        sess: &Session,
-    ) -> LevelAndSource {
-        let (level, mut src) = self.get_lint_id_level(LintId::of(lint), idx, aux);
-
-        // If `level` is none then we actually assume the default level for this
-        // lint.
-        let mut level = level.unwrap_or_else(|| lint.default_level(sess.edition()));
-
-        // If we're about to issue a warning, check at the last minute for any
-        // directives against the warnings "lint". If, for example, there's an
-        // `allow(warnings)` in scope then we want to respect that instead.
-        //
-        // We exempt `FORBIDDEN_LINT_GROUPS` from this because it specifically
-        // triggers in cases (like #80988) where you have `forbid(warnings)`,
-        // and so if we turned that into an error, it'd defeat the purpose of the
-        // future compatibility warning.
-        if level == Level::Warn && LintId::of(lint) != LintId::of(FORBIDDEN_LINT_GROUPS) {
-            let (warnings_level, warnings_src) =
-                self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux);
-            if let Some(configured_warning_level) = warnings_level {
-                if configured_warning_level != Level::Warn {
-                    level = configured_warning_level;
-                    src = warnings_src;
-                }
+/// From an initial level and source, verify the effect of special annotations:
+/// `warnings` lint level and lint caps.
+///
+/// The return of this function is suitable for diagnostics.
+pub fn reveal_actual_level(
+    level: Option<Level>,
+    src: &mut LintLevelSource,
+    sess: &Session,
+    lint: LintId,
+    probe_for_lint_level: impl FnOnce(LintId) -> (Option<Level>, LintLevelSource),
+) -> Level {
+    // If `level` is none then we actually assume the default level for this lint.
+    let mut level = level.unwrap_or_else(|| lint.lint.default_level(sess.edition()));
+
+    // If we're about to issue a warning, check at the last minute for any
+    // directives against the warnings "lint". If, for example, there's an
+    // `allow(warnings)` in scope then we want to respect that instead.
+    //
+    // We exempt `FORBIDDEN_LINT_GROUPS` from this because it specifically
+    // triggers in cases (like #80988) where you have `forbid(warnings)`,
+    // and so if we turned that into an error, it'd defeat the purpose of the
+    // future compatibility warning.
+    if level == Level::Warn && lint != LintId::of(FORBIDDEN_LINT_GROUPS) {
+        let (warnings_level, warnings_src) = probe_for_lint_level(LintId::of(builtin::WARNINGS));
+        if let Some(configured_warning_level) = warnings_level {
+            if configured_warning_level != Level::Warn {
+                level = configured_warning_level;
+                *src = warnings_src;
             }
         }
+    }
 
-        // Ensure that we never exceed the `--cap-lints` argument
-        // unless the source is a --force-warn
-        level = if let LintLevelSource::CommandLine(_, Level::ForceWarn(_)) = src {
-            level
-        } else {
-            cmp::min(level, self.lint_cap)
-        };
-
-        if let Some(driver_level) = sess.driver_lint_caps.get(&LintId::of(lint)) {
-            // Ensure that we never exceed driver level.
-            level = cmp::min(*driver_level, level);
-        }
+    // Ensure that we never exceed the `--cap-lints` argument unless the source is a --force-warn
+    level = if let LintLevelSource::CommandLine(_, Level::ForceWarn(_)) = src {
+        level
+    } else {
+        cmp::min(level, sess.opts.lint_cap.unwrap_or(Level::Forbid))
+    };
 
-        (level, src)
+    if let Some(driver_level) = sess.driver_lint_caps.get(&lint) {
+        // Ensure that we never exceed driver level.
+        level = cmp::min(*driver_level, level);
     }
 
-    pub fn get_lint_id_level(
+    level
+}
+
+impl ShallowLintLevelMap {
+    /// Perform a deep probe in the HIR tree looking for the actual level for the lint.
+    /// This lint level is not usable for diagnostics, it needs to be corrected by
+    /// `reveal_actual_level` beforehand.
+    #[instrument(level = "trace", skip(self, tcx), ret)]
+    fn probe_for_lint_level(
         &self,
+        tcx: TyCtxt<'_>,
         id: LintId,
-        mut idx: LintStackIndex,
-        aux: Option<&FxHashMap<LintId, LevelAndSource>>,
+        start: HirId,
     ) -> (Option<Level>, LintLevelSource) {
-        if let Some(specs) = aux {
-            if let Some(&(level, src)) = specs.get(&id) {
-                return (Some(level), src);
-            }
+        if let Some(map) = self.specs.get(&start.local_id)
+            && let Some(&(level, src)) = map.get(&id)
+        {
+            return (Some(level), src);
         }
-        loop {
-            let LintSet { ref specs, parent } = self.list[idx];
-            if let Some(&(level, src)) = specs.get(&id) {
-                return (Some(level), src);
+
+        let mut owner = start.owner;
+        let mut specs = &self.specs;
+
+        for parent in tcx.hir().parent_id_iter(start) {
+            if parent.owner != owner {
+                owner = parent.owner;
+                specs = &tcx.shallow_lint_levels_on(owner).specs;
             }
-            if idx == COMMAND_LINE {
-                return (None, LintLevelSource::Default);
+            if let Some(map) = specs.get(&parent.local_id)
+                && let Some(&(level, src)) = map.get(&id)
+            {
+                return (Some(level), src);
             }
-            idx = parent;
         }
-    }
-}
 
-#[derive(Debug)]
-pub struct LintLevelMap {
-    /// This is a collection of lint expectations as described in RFC 2383, that
-    /// can be fulfilled during this compilation session. This means that at least
-    /// one expected lint is currently registered in the lint store.
-    ///
-    /// The [`LintExpectationId`] is stored as a part of the [`Expect`](Level::Expect)
-    /// lint level.
-    pub lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
-    pub sets: LintLevelSets,
-    pub id_to_set: FxHashMap<HirId, LintStackIndex>,
-}
+        (None, LintLevelSource::Default)
+    }
 
-impl LintLevelMap {
-    /// If the `id` was previously registered with `register_id` when building
-    /// this `LintLevelMap` this returns the corresponding lint level and source
-    /// of the lint level for the lint provided.
-    ///
-    /// If the `id` was not previously registered, returns `None`. If `None` is
-    /// returned then the parent of `id` should be acquired and this function
-    /// should be called again.
-    pub fn level_and_source(
+    /// Fetch and return the user-visible lint level for the given lint at the given HirId.
+    #[instrument(level = "trace", skip(self, tcx), ret)]
+    pub fn lint_level_id_at_node(
         &self,
-        lint: &'static Lint,
-        id: HirId,
-        session: &Session,
-    ) -> Option<LevelAndSource> {
-        self.id_to_set.get(&id).map(|idx| self.sets.get_lint_level(lint, *idx, None, session))
+        tcx: TyCtxt<'_>,
+        lint: LintId,
+        cur: HirId,
+    ) -> (Level, LintLevelSource) {
+        let (level, mut src) = self.probe_for_lint_level(tcx, lint, cur);
+        let level = reveal_actual_level(level, &mut src, tcx.sess, lint, |lint| {
+            self.probe_for_lint_level(tcx, lint, cur)
+        });
+        (level, src)
     }
 }
 
-impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
-    #[inline]
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        let LintLevelMap { ref sets, ref id_to_set, ref lint_expectations } = *self;
+impl TyCtxt<'_> {
+    /// Fetch and return the user-visible lint level for the given lint at the given HirId.
+    pub fn lint_level_at_node(self, lint: &'static Lint, id: HirId) -> (Level, LintLevelSource) {
+        self.shallow_lint_levels_on(id.owner).lint_level_id_at_node(self, LintId::of(lint), id)
+    }
 
-        id_to_set.hash_stable(hcx, hasher);
-        lint_expectations.hash_stable(hcx, hasher);
+    /// Walks upwards from `id` to find a node which might change lint levels with attributes.
+    /// It stops at `bound` and just returns it if reached.
+    pub fn maybe_lint_level_root_bounded(self, mut id: HirId, bound: HirId) -> HirId {
+        let hir = self.hir();
+        loop {
+            if id == bound {
+                return bound;
+            }
 
-        hcx.while_hashing_spans(true, |hcx| sets.hash_stable(hcx, hasher))
+            if hir.attrs(id).iter().any(|attr| Level::from_attr(attr).is_some()) {
+                return id;
+            }
+            let next = hir.get_parent_node(id);
+            if next == id {
+                bug!("lint traversal reached the root of the crate");
+            }
+            id = next;
+        }
     }
 }
 
@@ -261,11 +258,11 @@ pub fn explain_lint_level_source(
                 ));
             }
         }
-        LintLevelSource::Node(lint_attr_name, src, reason) => {
+        LintLevelSource::Node { name: lint_attr_name, span, reason, .. } => {
             if let Some(rationale) = reason {
                 err.note(rationale.as_str());
             }
-            err.span_note_once(src, "the lint level is defined here");
+            err.span_note_once(span, "the lint level is defined here");
             if lint_attr_name.as_str() != name {
                 let level_str = level.as_str();
                 err.note_once(&format!(
@@ -277,23 +274,65 @@ pub fn explain_lint_level_source(
     }
 }
 
-pub fn struct_lint_level<'s, 'd>(
-    sess: &'s Session,
+/// The innermost function for emitting lints.
+///
+/// If you are loocking to implement a lint, look for higher level functions,
+/// for example:
+/// - [`TyCtxt::emit_spanned_lint`]
+/// - [`TyCtxt::struct_span_lint_hir`]
+/// - [`TyCtxt::emit_lint`]
+/// - [`TyCtxt::struct_lint_node`]
+/// - `LintContext::lookup`
+///
+/// ## `decorate` signature
+///
+/// The return value of `decorate` is ignored by this function. So what is the
+/// point of returning `&'b mut DiagnosticBuilder<'a, ()>`?
+///
+/// There are 2 reasons for this signature.
+///
+/// First of all, it prevents accidental use of `.emit()` -- it's clear that the
+/// builder will be later used and shouldn't be emitted right away (this is
+/// especially important because the old API expected you to call `.emit()` in
+/// the closure).
+///
+/// Second of all, it makes the most common case of adding just a single label
+/// /suggestion much nicer, since [`DiagnosticBuilder`] methods return
+/// `&mut DiagnosticBuilder`, you can just chain methods, without needed
+/// awkward `{ ...; }`:
+/// ```ignore pseudo-code
+/// struct_lint_level(
+///     ...,
+///     |lint| lint.span_label(sp, "lbl")
+///     //          ^^^^^^^^^^^^^^^^^^^^^ returns `&mut DiagnosticBuilder` by default
+/// )
+/// ```
+pub fn struct_lint_level(
+    sess: &Session,
     lint: &'static Lint,
     level: Level,
     src: LintLevelSource,
     span: Option<MultiSpan>,
-    decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) + 'd,
+    msg: impl Into<DiagnosticMessage>,
+    decorate: impl for<'a, 'b> FnOnce(
+        &'b mut DiagnosticBuilder<'a, ()>,
+    ) -> &'b mut DiagnosticBuilder<'a, ()>,
 ) {
     // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
     // the "real" work.
-    fn struct_lint_level_impl<'s, 'd>(
-        sess: &'s Session,
+    fn struct_lint_level_impl(
+        sess: &Session,
         lint: &'static Lint,
         level: Level,
         src: LintLevelSource,
         span: Option<MultiSpan>,
-        decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b, ()>) + 'd>,
+        msg: impl Into<DiagnosticMessage>,
+        decorate: Box<
+            dyn '_
+                + for<'a, 'b> FnOnce(
+                    &'b mut DiagnosticBuilder<'a, ()>,
+                ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        >,
     ) {
         // Check for future incompatibility lints and issue a stronger warning.
         let future_incompatible = lint.future_incompatible;
@@ -344,6 +383,8 @@ pub fn struct_lint_level<'s, 'd>(
             (Level::Deny | Level::Forbid, None) => sess.diagnostic().struct_err_lint(""),
         };
 
+        err.set_is_lint();
+
         // If this code originates in a foreign macro, aka something that this crate
         // did not itself author, then it's likely that there's nothing this crate
         // can do about it. We probably want to skip the lint entirely.
@@ -366,6 +407,10 @@ pub fn struct_lint_level<'s, 'd>(
             }
         }
 
+        // Delay evaluating and setting the primary message until after we've
+        // suppressed the lint due to macros.
+        err.set_primary_message(msg);
+
         // Lint diagnostics that are covered by the expect level will not be emitted outside
         // the compiler. It is therefore not necessary to add any information for the user.
         // This will therefore directly call the decorate function which will in turn emit
@@ -373,12 +418,12 @@ pub fn struct_lint_level<'s, 'd>(
         if let Level::Expect(_) = level {
             let name = lint.name_lower();
             err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn: false });
-            decorate(LintDiagnosticBuilder::new(err));
+
+            decorate(&mut err);
+            err.emit();
             return;
         }
 
-        explain_lint_level_source(lint, level, src, &mut err);
-
         let name = lint.name_lower();
         let is_force_warn = matches!(level, Level::ForceWarn(_));
         err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn });
@@ -417,10 +462,12 @@ pub fn struct_lint_level<'s, 'd>(
             }
         }
 
-        // Finally, run `decorate`. This function is also responsible for emitting the diagnostic.
-        decorate(LintDiagnosticBuilder::new(err));
+        // Finally, run `decorate`.
+        decorate(&mut err);
+        explain_lint_level_source(lint, level, src, &mut *err);
+        err.emit()
     }
-    struct_lint_level_impl(sess, lint, level, src, span, Box::new(decorate))
+    struct_lint_level_impl(sess, lint, level, src, span, msg, Box::new(decorate))
 }
 
 /// Returns whether `span` originates in a foreign crate's external macro.
@@ -432,7 +479,9 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
     match expn_data.kind {
         ExpnKind::Inlined
         | ExpnKind::Root
-        | ExpnKind::Desugaring(DesugaringKind::ForLoop | DesugaringKind::WhileLoop) => false,
+        | ExpnKind::Desugaring(
+            DesugaringKind::ForLoop | DesugaringKind::WhileLoop | DesugaringKind::OpaqueTy,
+        ) => false,
         ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
         ExpnKind::Macro(MacroKind::Bang, _) => {
             // Dummy span for the `def_site` means it's an external macro.
diff --git a/compiler/rustc_middle/src/macros.rs b/compiler/rustc_middle/src/macros.rs
index 0e85c60a3..01fe72de6 100644
--- a/compiler/rustc_middle/src/macros.rs
+++ b/compiler/rustc_middle/src/macros.rs
@@ -54,13 +54,22 @@ macro_rules! TrivialTypeTraversalImpls {
             impl<$tcx> $crate::ty::fold::TypeFoldable<$tcx> for $ty {
                 fn try_fold_with<F: $crate::ty::fold::FallibleTypeFolder<$tcx>>(
                     self,
-                    _: &mut F
-                ) -> ::std::result::Result<$ty, F::Error> {
+                    _: &mut F,
+                ) -> ::std::result::Result<Self, F::Error> {
                     Ok(self)
                 }
+
+                #[inline]
+                fn fold_with<F: $crate::ty::fold::TypeFolder<$tcx>>(
+                    self,
+                    _: &mut F,
+                ) -> Self {
+                    self
+                }
             }
 
             impl<$tcx> $crate::ty::visit::TypeVisitable<$tcx> for $ty {
+                #[inline]
                 fn visit_with<F: $crate::ty::visit::TypeVisitor<$tcx>>(
                     &self,
                     _: &mut F)
diff --git a/compiler/rustc_middle/src/middle/limits.rs b/compiler/rustc_middle/src/middle/limits.rs
index 53c4d9267..12aef66bc 100644
--- a/compiler/rustc_middle/src/middle/limits.rs
+++ b/compiler/rustc_middle/src/middle/limits.rs
@@ -38,7 +38,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
             tcx.hir().krate_attrs(),
             tcx.sess,
             sym::const_eval_limit,
-            1_000_000,
+            2_000_000,
         ),
     }
 }
diff --git a/compiler/rustc_middle/src/middle/privacy.rs b/compiler/rustc_middle/src/middle/privacy.rs
index 751c7f464..9c68c7504 100644
--- a/compiler/rustc_middle/src/middle/privacy.rs
+++ b/compiler/rustc_middle/src/middle/privacy.rs
@@ -1,64 +1,218 @@
 //! A pass that checks to make sure private fields and methods aren't used
 //! outside their scopes. This pass will also generate a set of exported items
 //! which are available for use externally when compiled as a library.
-
+use crate::ty::{DefIdTree, Visibility};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_macros::HashStable;
 use rustc_query_system::ich::StableHashingContext;
-use rustc_span::def_id::LocalDefId;
+use rustc_span::def_id::{DefId, LocalDefId};
 use std::hash::Hash;
 
-/// Represents the levels of accessibility an item can have.
+/// Represents the levels of effective visibility an item can have.
 ///
-/// The variants are sorted in ascending order of accessibility.
+/// The variants are sorted in ascending order of directness.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, HashStable)]
-pub enum AccessLevel {
-    /// Superset of `AccessLevel::Reachable` used to mark impl Trait items.
-    ReachableFromImplTrait,
-    /// Exported items + items participating in various kinds of public interfaces,
-    /// but not directly nameable. For example, if function `fn f() -> T {...}` is
-    /// public, then type `T` is reachable. Its values can be obtained by other crates
-    /// even if the type itself is not nameable.
+pub enum Level {
+    /// Superset of `Reachable` including items leaked through return position `impl Trait`.
+    ReachableThroughImplTrait,
+    /// Item is either reexported, or leaked through any kind of interface.
+    /// For example, if function `fn f() -> T {...}` is directly public, then type `T` is publicly
+    /// reachable and its values can be obtained by other crates even if the type itself is not
+    /// nameable.
     Reachable,
-    /// Public items + items accessible to other crates with the help of `pub use` re-exports.
-    Exported,
-    /// Items accessible to other crates directly, without the help of re-exports.
-    Public,
+    /// Item is accessible either directly, or with help of `use` reexports.
+    Reexported,
+    /// Item is directly accessible, without help of reexports.
+    Direct,
+}
+
+impl Level {
+    pub fn all_levels() -> [Level; 4] {
+        [Level::Direct, Level::Reexported, Level::Reachable, Level::ReachableThroughImplTrait]
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
+pub struct EffectiveVisibility {
+    direct: Visibility,
+    reexported: Visibility,
+    reachable: Visibility,
+    reachable_through_impl_trait: Visibility,
+}
+
+impl EffectiveVisibility {
+    pub fn at_level(&self, level: Level) -> &Visibility {
+        match level {
+            Level::Direct => &self.direct,
+            Level::Reexported => &self.reexported,
+            Level::Reachable => &self.reachable,
+            Level::ReachableThroughImplTrait => &self.reachable_through_impl_trait,
+        }
+    }
+
+    fn at_level_mut(&mut self, level: Level) -> &mut Visibility {
+        match level {
+            Level::Direct => &mut self.direct,
+            Level::Reexported => &mut self.reexported,
+            Level::Reachable => &mut self.reachable,
+            Level::ReachableThroughImplTrait => &mut self.reachable_through_impl_trait,
+        }
+    }
+
+    pub fn is_public_at_level(&self, level: Level) -> bool {
+        self.at_level(level).is_public()
+    }
+
+    pub fn from_vis(vis: Visibility) -> EffectiveVisibility {
+        EffectiveVisibility {
+            direct: vis,
+            reexported: vis,
+            reachable: vis,
+            reachable_through_impl_trait: vis,
+        }
+    }
 }
 
-/// Holds a map of accessibility levels for reachable HIR nodes.
+/// Holds a map of effective visibilities for reachable HIR nodes.
 #[derive(Debug, Clone)]
-pub struct AccessLevels<Id = LocalDefId> {
-    pub map: FxHashMap<Id, AccessLevel>,
+pub struct EffectiveVisibilities<Id = LocalDefId> {
+    map: FxHashMap<Id, EffectiveVisibility>,
 }
 
-impl<Id: Hash + Eq> AccessLevels<Id> {
-    /// See `AccessLevel::Reachable`.
+impl<Id: Hash + Eq + Copy> EffectiveVisibilities<Id> {
+    pub fn is_public_at_level(&self, id: Id, level: Level) -> bool {
+        self.effective_vis(id)
+            .map_or(false, |effective_vis| effective_vis.is_public_at_level(level))
+    }
+
+    /// See `Level::Reachable`.
     pub fn is_reachable(&self, id: Id) -> bool {
-        self.map.get(&id) >= Some(&AccessLevel::Reachable)
+        self.is_public_at_level(id, Level::Reachable)
     }
 
-    /// See `AccessLevel::Exported`.
+    /// See `Level::Reexported`.
     pub fn is_exported(&self, id: Id) -> bool {
-        self.map.get(&id) >= Some(&AccessLevel::Exported)
+        self.is_public_at_level(id, Level::Reexported)
+    }
+
+    /// See `Level::Direct`.
+    pub fn is_directly_public(&self, id: Id) -> bool {
+        self.is_public_at_level(id, Level::Direct)
+    }
+
+    pub fn public_at_level(&self, id: Id) -> Option<Level> {
+        self.effective_vis(id).and_then(|effective_vis| {
+            for level in Level::all_levels() {
+                if effective_vis.is_public_at_level(level) {
+                    return Some(level);
+                }
+            }
+            None
+        })
+    }
+
+    pub fn effective_vis(&self, id: Id) -> Option<&EffectiveVisibility> {
+        self.map.get(&id)
     }
 
-    /// See `AccessLevel::Public`.
-    pub fn is_public(&self, id: Id) -> bool {
-        self.map.get(&id) >= Some(&AccessLevel::Public)
+    pub fn iter(&self) -> impl Iterator<Item = (&Id, &EffectiveVisibility)> {
+        self.map.iter()
+    }
+
+    pub fn map_id<OutId: Hash + Eq + Copy>(
+        &self,
+        f: impl Fn(Id) -> OutId,
+    ) -> EffectiveVisibilities<OutId> {
+        EffectiveVisibilities { map: self.map.iter().map(|(k, v)| (f(*k), *v)).collect() }
+    }
+
+    pub fn set_public_at_level(
+        &mut self,
+        id: Id,
+        default_vis: impl FnOnce() -> Visibility,
+        level: Level,
+    ) {
+        let mut effective_vis = self
+            .effective_vis(id)
+            .copied()
+            .unwrap_or_else(|| EffectiveVisibility::from_vis(default_vis()));
+        for l in Level::all_levels() {
+            if l <= level {
+                *effective_vis.at_level_mut(l) = Visibility::Public;
+            }
+        }
+        self.map.insert(id, effective_vis);
+    }
+}
+
+impl<Id: Hash + Eq + Copy + Into<DefId>> EffectiveVisibilities<Id> {
+    // `parent_id` is not necessarily a parent in source code tree,
+    // it is the node from which the maximum effective visibility is inherited.
+    pub fn update(
+        &mut self,
+        id: Id,
+        nominal_vis: Visibility,
+        default_vis: impl FnOnce() -> Visibility,
+        parent_id: Id,
+        level: Level,
+        tree: impl DefIdTree,
+    ) -> bool {
+        let mut changed = false;
+        let mut current_effective_vis = self.effective_vis(id).copied().unwrap_or_else(|| {
+            if id.into().is_crate_root() {
+                EffectiveVisibility::from_vis(Visibility::Public)
+            } else {
+                EffectiveVisibility::from_vis(default_vis())
+            }
+        });
+        if let Some(inherited_effective_vis) = self.effective_vis(parent_id) {
+            let mut inherited_effective_vis_at_prev_level =
+                *inherited_effective_vis.at_level(level);
+            let mut calculated_effective_vis = inherited_effective_vis_at_prev_level;
+            for l in Level::all_levels() {
+                if level >= l {
+                    let inherited_effective_vis_at_level = *inherited_effective_vis.at_level(l);
+                    let current_effective_vis_at_level = current_effective_vis.at_level_mut(l);
+                    // effective visibility for id shouldn't be recalculated if
+                    // inherited from parent_id effective visibility isn't changed at next level
+                    if !(inherited_effective_vis_at_prev_level == inherited_effective_vis_at_level
+                        && level != l)
+                    {
+                        calculated_effective_vis =
+                            if nominal_vis.is_at_least(inherited_effective_vis_at_level, tree) {
+                                inherited_effective_vis_at_level
+                            } else {
+                                nominal_vis
+                            };
+                    }
+                    // effective visibility can't be decreased at next update call for the
+                    // same id
+                    if *current_effective_vis_at_level != calculated_effective_vis
+                        && calculated_effective_vis
+                            .is_at_least(*current_effective_vis_at_level, tree)
+                    {
+                        changed = true;
+                        *current_effective_vis_at_level = calculated_effective_vis;
+                    }
+                    inherited_effective_vis_at_prev_level = inherited_effective_vis_at_level;
+                }
+            }
+        }
+        self.map.insert(id, current_effective_vis);
+        changed
     }
 }
 
-impl<Id> Default for AccessLevels<Id> {
+impl<Id> Default for EffectiveVisibilities<Id> {
     fn default() -> Self {
-        AccessLevels { map: Default::default() }
+        EffectiveVisibilities { map: Default::default() }
     }
 }
 
-impl<'a> HashStable<StableHashingContext<'a>> for AccessLevels {
+impl<'a> HashStable<StableHashingContext<'a>> for EffectiveVisibilities {
     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        let AccessLevels { ref map } = *self;
+        let EffectiveVisibilities { ref map } = *self;
         map.hash_stable(hcx, hasher);
     }
 }
diff --git a/compiler/rustc_middle/src/middle/resolve_lifetime.rs b/compiler/rustc_middle/src/middle/resolve_lifetime.rs
index a171f5711..c3bf1c717 100644
--- a/compiler/rustc_middle/src/middle/resolve_lifetime.rs
+++ b/compiler/rustc_middle/src/middle/resolve_lifetime.rs
@@ -2,9 +2,9 @@
 
 use crate::ty;
 
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::ItemLocalId;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::def_id::DefId;
+use rustc_hir::{ItemLocalId, OwnerId};
 use rustc_macros::HashStable;
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)]
@@ -49,12 +49,7 @@ pub enum ObjectLifetimeDefault {
 pub struct ResolveLifetimes {
     /// Maps from every use of a named (not anonymous) lifetime to a
     /// `Region` describing how that region is bound
-    pub defs: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Region>>,
+    pub defs: FxHashMap<OwnerId, FxHashMap<ItemLocalId, Region>>,
 
-    /// Set of lifetime def ids that are late-bound; a region can
-    /// be late-bound if (a) it does NOT appear in a where-clause and
-    /// (b) it DOES appear in the arguments.
-    pub late_bound: FxHashMap<LocalDefId, FxHashSet<LocalDefId>>,
-
-    pub late_bound_vars: FxHashMap<LocalDefId, FxHashMap<ItemLocalId, Vec<ty::BoundVariableKind>>>,
+    pub late_bound_vars: FxHashMap<OwnerId, FxHashMap<ItemLocalId, Vec<ty::BoundVariableKind>>>,
 }
diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs
index d182929c4..61bc089e4 100644
--- a/compiler/rustc_middle/src/middle/stability.rs
+++ b/compiler/rustc_middle/src/middle/stability.rs
@@ -253,13 +253,12 @@ fn late_report_deprecation(
         return;
     }
     let method_span = method_span.unwrap_or(span);
-    tcx.struct_span_lint_hir(lint, hir_id, method_span, |lint| {
-        let mut diag = lint.build(message);
+    tcx.struct_span_lint_hir(lint, hir_id, method_span, message, |diag| {
         if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
             let kind = tcx.def_kind(def_id).descr(def_id);
-            deprecation_suggestion(&mut diag, kind, suggestion, method_span);
+            deprecation_suggestion(diag, kind, suggestion, method_span);
         }
-        diag.emit();
+        diag
     });
 }
 
@@ -621,9 +620,7 @@ impl<'tcx> TyCtxt<'tcx> {
         unmarked: impl FnOnce(Span, DefId),
     ) -> bool {
         let soft_handler = |lint, span, msg: &_| {
-            self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {
-                lint.build(msg).emit();
-            })
+            self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg, |lint| lint)
         };
         let eval_result =
             self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable);
diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs
index e4039cc7c..b5a50cc15 100644
--- a/compiler/rustc_middle/src/mir/interpret/error.rs
+++ b/compiler/rustc_middle/src/mir/interpret/error.rs
@@ -479,12 +479,7 @@ impl<T: Any> AsAny for T {
 }
 
 /// A trait for machine-specific errors (or other "machine stop" conditions).
-pub trait MachineStopType: AsAny + fmt::Display + Send {
-    /// If `true`, emit a hard error instead of going through the `CONST_ERR` lint
-    fn is_hard_err(&self) -> bool {
-        false
-    }
-}
+pub trait MachineStopType: AsAny + fmt::Display + Send {}
 
 impl dyn MachineStopType {
     #[inline(always)]
@@ -543,16 +538,4 @@ impl InterpError<'_> {
                 | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_))
         )
     }
-
-    /// Should this error be reported as a hard error, preventing compilation, or a soft error,
-    /// causing a deny-by-default lint?
-    pub fn is_hard_err(&self) -> bool {
-        use InterpError::*;
-        match *self {
-            MachineStop(ref err) => err.is_hard_err(),
-            UndefinedBehavior(_) => true,
-            ResourceExhaustion(ResourceExhaustionInfo::MemoryExhausted) => true,
-            _ => false,
-        }
-    }
 }
diff --git a/compiler/rustc_middle/src/mir/interpret/pointer.rs b/compiler/rustc_middle/src/mir/interpret/pointer.rs
index 95e52e391..23c2ce647 100644
--- a/compiler/rustc_middle/src/mir/interpret/pointer.rs
+++ b/compiler/rustc_middle/src/mir/interpret/pointer.rs
@@ -43,7 +43,7 @@ pub trait PointerArithmetic: HasDataLayout {
         let val = val as i64;
         // Now wrap-around into the machine_isize range.
         if val > self.machine_isize_max() {
-            // This can only happen the the ptr size is < 64, so we know max_usize_plus_1 fits into
+            // This can only happen if the ptr size is < 64, so we know max_usize_plus_1 fits into
             // i64.
             debug_assert!(self.pointer_size().bits() < 64);
             let max_usize_plus_1 = 1u128 << self.pointer_size().bits();
diff --git a/compiler/rustc_middle/src/mir/interpret/queries.rs b/compiler/rustc_middle/src/mir/interpret/queries.rs
index 4207988d7..473894ac1 100644
--- a/compiler/rustc_middle/src/mir/interpret/queries.rs
+++ b/compiler/rustc_middle/src/mir/interpret/queries.rs
@@ -4,7 +4,9 @@ use crate::mir;
 use crate::ty::subst::InternalSubsts;
 use crate::ty::visit::TypeVisitable;
 use crate::ty::{self, query::TyCtxtAt, query::TyCtxtEnsure, TyCtxt};
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
+use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 
 impl<'tcx> TyCtxt<'tcx> {
@@ -36,7 +38,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn const_eval_resolve(
         self,
         param_env: ty::ParamEnv<'tcx>,
-        ct: ty::Unevaluated<'tcx>,
+        ct: mir::UnevaluatedConst<'tcx>,
         span: Option<Span>,
     ) -> EvalToConstValueResult<'tcx> {
         // Cannot resolve `Unevaluated` constants that contain inference
@@ -45,11 +47,15 @@ impl<'tcx> TyCtxt<'tcx> {
         //
         // When trying to evaluate constants containing inference variables,
         // use `Infcx::const_eval_resolve` instead.
-        if ct.substs.has_infer_types_or_consts() {
+        if ct.substs.has_non_region_infer() {
             bug!("did not expect inference variables here");
         }
 
-        match ty::Instance::resolve_opt_const_arg(self, param_env, ct.def, ct.substs) {
+        match ty::Instance::resolve_opt_const_arg(
+            self, param_env,
+            // FIXME: maybe have a separate version for resolving mir::UnevaluatedConst?
+            ct.def, ct.substs,
+        ) {
             Ok(Some(instance)) => {
                 let cid = GlobalId { instance, promoted: ct.promoted };
                 self.const_eval_global_id(param_env, cid, span)
@@ -63,7 +69,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn const_eval_resolve_for_typeck(
         self,
         param_env: ty::ParamEnv<'tcx>,
-        ct: ty::Unevaluated<'tcx, ()>,
+        ct: ty::UnevaluatedConst<'tcx>,
         span: Option<Span>,
     ) -> EvalToValTreeResult<'tcx> {
         // Cannot resolve `Unevaluated` constants that contain inference
@@ -72,14 +78,36 @@ impl<'tcx> TyCtxt<'tcx> {
         //
         // When trying to evaluate constants containing inference variables,
         // use `Infcx::const_eval_resolve` instead.
-        if ct.substs.has_infer_types_or_consts() {
+        if ct.substs.has_non_region_infer() {
             bug!("did not expect inference variables here");
         }
 
         match ty::Instance::resolve_opt_const_arg(self, param_env, ct.def, ct.substs) {
             Ok(Some(instance)) => {
                 let cid = GlobalId { instance, promoted: None };
-                self.const_eval_global_id_for_typeck(param_env, cid, span)
+                self.const_eval_global_id_for_typeck(param_env, cid, span).inspect(|_| {
+                    // We are emitting the lint here instead of in `is_const_evaluatable`
+                    // as we normalize obligations before checking them, and normalization
+                    // uses this function to evaluate this constant.
+                    //
+                    // @lcnr believes that successfully evaluating even though there are
+                    // used generic parameters is a bug of evaluation, so checking for it
+                    // here does feel somewhat sensible.
+                    if !self.features().generic_const_exprs && ct.substs.has_non_region_param() {
+                        assert!(matches!(self.def_kind(ct.def.did), DefKind::AnonConst));
+                        let mir_body = self.mir_for_ctfe_opt_const_arg(ct.def);
+                        if mir_body.is_polymorphic {
+                            let Some(local_def_id) = ct.def.did.as_local() else { return };
+                            self.struct_span_lint_hir(
+                                lint::builtin::CONST_EVALUATABLE_UNCHECKED,
+                                self.hir().local_def_id_to_hir_id(local_def_id),
+                                self.def_span(ct.def.did),
+                                "cannot use constants which depend on generic parameters in types",
+                                |err| err,
+                            )
+                        }
+                    }
+                })
             }
             Ok(None) => Err(ErrorHandled::TooGeneric),
             Err(error_reported) => Err(ErrorHandled::Reported(error_reported)),
@@ -211,7 +239,7 @@ impl<'tcx> TyCtxt<'tcx> {
         self,
         param_env: ty::ParamEnv<'tcx>,
         constant: mir::ConstantKind<'tcx>,
-    ) -> mir::DestructuredMirConstant<'tcx> {
+    ) -> mir::DestructuredConstant<'tcx> {
         self.try_destructure_mir_constant(param_env.and(constant)).unwrap()
     }
 }
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 3d7a6230e..79db35a76 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -7,12 +7,12 @@ use crate::mir::interpret::{
 };
 use crate::mir::visit::MirVisitable;
 use crate::ty::codec::{TyDecoder, TyEncoder};
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
+use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
 use crate::ty::print::{FmtPrinter, Printer};
-use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
-use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use crate::ty::visit::{TypeVisitable, TypeVisitor};
 use crate::ty::{self, List, Ty, TyCtxt};
 use crate::ty::{AdtDef, InstanceDef, ScalarInt, UserTypeAnnotationIndex};
+use crate::ty::{GenericArg, InternalSubsts, SubstsRef};
 
 use rustc_data_structures::captures::Captures;
 use rustc_errors::ErrorGuaranteed;
@@ -116,11 +116,6 @@ pub trait MirPass<'tcx> {
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
 
-    /// If this pass causes the MIR to enter a new phase, return that phase.
-    fn phase_change(&self) -> Option<MirPhase> {
-        None
-    }
-
     fn is_mir_dump_enabled(&self) -> bool {
         true
     }
@@ -145,6 +140,35 @@ impl MirPhase {
     }
 }
 
+impl Display for MirPhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            MirPhase::Built => write!(f, "built"),
+            MirPhase::Analysis(p) => write!(f, "analysis-{}", p),
+            MirPhase::Runtime(p) => write!(f, "runtime-{}", p),
+        }
+    }
+}
+
+impl Display for AnalysisPhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            AnalysisPhase::Initial => write!(f, "initial"),
+            AnalysisPhase::PostCleanup => write!(f, "post_cleanup"),
+        }
+    }
+}
+
+impl Display for RuntimePhase {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            RuntimePhase::Initial => write!(f, "initial"),
+            RuntimePhase::PostCleanup => write!(f, "post_cleanup"),
+            RuntimePhase::Optimized => write!(f, "optimized"),
+        }
+    }
+}
+
 /// Where a specific `mir::Body` comes from.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
@@ -207,6 +231,9 @@ pub struct Body<'tcx> {
     /// us to see the difference and forego optimization on the inlined promoted items.
     pub phase: MirPhase,
 
+    /// How many passses we have executed since starting the current phase. Used for debug output.
+    pub pass_count: usize,
+
     pub source: MirSource<'tcx>,
 
     /// A list of source scopes; these are referenced by statements
@@ -292,6 +319,7 @@ impl<'tcx> Body<'tcx> {
 
         let mut body = Body {
             phase: MirPhase::Built,
+            pass_count: 1,
             source,
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes,
@@ -313,7 +341,7 @@ impl<'tcx> Body<'tcx> {
             is_polymorphic: false,
             tainted_by_errors,
         };
-        body.is_polymorphic = body.has_param_types_or_consts();
+        body.is_polymorphic = body.has_non_region_param();
         body
     }
 
@@ -325,6 +353,7 @@ impl<'tcx> Body<'tcx> {
     pub fn new_cfg_only(basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>) -> Self {
         let mut body = Body {
             phase: MirPhase::Built,
+            pass_count: 1,
             source: MirSource::item(CRATE_DEF_ID.to_def_id()),
             basic_blocks: BasicBlocks::new(basic_blocks),
             source_scopes: IndexVec::new(),
@@ -339,7 +368,7 @@ impl<'tcx> Body<'tcx> {
             is_polymorphic: false,
             tainted_by_errors: None,
         };
-        body.is_polymorphic = body.has_param_types_or_consts();
+        body.is_polymorphic = body.has_non_region_param();
         body
     }
 
@@ -1380,6 +1409,7 @@ impl<V, T> ProjectionElem<V, T> {
 
             Self::Field(_, _)
             | Self::Index(_)
+            | Self::OpaqueCast(_)
             | Self::ConstantIndex { .. }
             | Self::Subslice { .. }
             | Self::Downcast(_, _) => false,
@@ -1574,7 +1604,9 @@ impl Debug for Place<'_> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         for elem in self.projection.iter().rev() {
             match elem {
-                ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => {
+                ProjectionElem::OpaqueCast(_)
+                | ProjectionElem::Downcast(_, _)
+                | ProjectionElem::Field(_, _) => {
                     write!(fmt, "(").unwrap();
                 }
                 ProjectionElem::Deref => {
@@ -1590,6 +1622,9 @@ impl Debug for Place<'_> {
 
         for elem in self.projection.iter() {
             match elem {
+                ProjectionElem::OpaqueCast(ty) => {
+                    write!(fmt, " as {})", ty)?;
+                }
                 ProjectionElem::Downcast(Some(name), _index) => {
                     write!(fmt, " as {})", name)?;
                 }
@@ -1818,7 +1853,6 @@ impl<'tcx> Rvalue<'tcx> {
             // While the model is undecided, we should be conservative. See
             // <https://www.ralfj.de/blog/2022/04/11/provenance-exposed.html>
             Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
-            Rvalue::Cast(CastKind::DynStar, _, _) => false,
 
             Rvalue::Use(_)
             | Rvalue::CopyForDeref(_)
@@ -1828,7 +1862,15 @@ impl<'tcx> Rvalue<'tcx> {
             | Rvalue::AddressOf(_, _)
             | Rvalue::Len(_)
             | Rvalue::Cast(
-                CastKind::Misc | CastKind::Pointer(_) | CastKind::PointerFromExposedAddress,
+                CastKind::IntToInt
+                | CastKind::FloatToInt
+                | CastKind::FloatToFloat
+                | CastKind::IntToFloat
+                | CastKind::FnPtrToPtr
+                | CastKind::PtrToPtr
+                | CastKind::Pointer(_)
+                | CastKind::PointerFromExposedAddress
+                | CastKind::DynStar,
                 _,
                 _,
             )
@@ -2043,13 +2085,13 @@ pub struct Constant<'tcx> {
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)]
-#[derive(Lift)]
+#[derive(Lift, TypeFoldable, TypeVisitable)]
 pub enum ConstantKind<'tcx> {
     /// This constant came from the type system
     Ty(ty::Const<'tcx>),
 
     /// An unevaluated mir constant which is not part of the type system.
-    Unevaluated(ty::Unevaluated<'tcx, Option<Promoted>>, Ty<'tcx>),
+    Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>),
 
     /// This constant cannot go back into the type system, as it represents
     /// something the type system cannot handle (e.g. pointers).
@@ -2309,12 +2351,11 @@ impl<'tcx> ConstantKind<'tcx> {
             ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
                 .substs;
 
-        let uneval = ty::Unevaluated {
+        let uneval = UnevaluatedConst {
             def: ty::WithOptConstParam::unknown(def_id).to_global(),
             substs,
             promoted: None,
         };
-
         debug_assert!(!uneval.has_free_regions());
 
         Self::Unevaluated(uneval, ty)
@@ -2398,7 +2439,7 @@ impl<'tcx> ConstantKind<'tcx> {
 
         let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
         let span = tcx.hir().span(hir_id);
-        let uneval = ty::Unevaluated::new(def.to_global(), substs);
+        let uneval = UnevaluatedConst::new(def.to_global(), substs);
         debug!(?span, ?param_env);
 
         match tcx.const_eval_resolve(param_env, uneval, Some(span)) {
@@ -2411,7 +2452,7 @@ impl<'tcx> ConstantKind<'tcx> {
                 // Error was handled in `const_eval_resolve`. Here we just create a
                 // new unevaluated const and error hard later in codegen
                 Self::Unevaluated(
-                    ty::Unevaluated {
+                    UnevaluatedConst {
                         def: def.to_global(),
                         substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
                         promoted: None,
@@ -2434,6 +2475,34 @@ impl<'tcx> ConstantKind<'tcx> {
     }
 }
 
+/// An unevaluated (potentially generic) constant used in MIR.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Lift)]
+#[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
+pub struct UnevaluatedConst<'tcx> {
+    pub def: ty::WithOptConstParam<DefId>,
+    pub substs: SubstsRef<'tcx>,
+    pub promoted: Option<Promoted>,
+}
+
+impl<'tcx> UnevaluatedConst<'tcx> {
+    // FIXME: probably should get rid of this method. It's also wrong to
+    // shrink and then later expand a promoted.
+    #[inline]
+    pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> {
+        ty::UnevaluatedConst { def: self.def, substs: self.substs }
+    }
+}
+
+impl<'tcx> UnevaluatedConst<'tcx> {
+    #[inline]
+    pub fn new(
+        def: ty::WithOptConstParam<DefId>,
+        substs: SubstsRef<'tcx>,
+    ) -> UnevaluatedConst<'tcx> {
+        UnevaluatedConst { def, substs, promoted: Default::default() }
+    }
+}
+
 /// A collection of projections into user types.
 ///
 /// They are projections because a binding can occur a part of a
@@ -2727,7 +2796,7 @@ fn pretty_print_const_value<'tcx>(
             }
             // Aggregates, printed as array/tuple/struct/variant construction syntax.
             //
-            // NB: the `has_param_types_or_consts` check ensures that we can use
+            // NB: the `has_non_region_param` check ensures that we can use
             // the `destructure_const` query with an empty `ty::ParamEnv` without
             // introducing ICEs (e.g. via `layout_of`) from missing bounds.
             // E.g. `transmute([0usize; 2]): (u8, *mut T)` needs to know `T: Sized`
@@ -2735,7 +2804,7 @@ fn pretty_print_const_value<'tcx>(
             //
             // FIXME(eddyb) for `--emit=mir`/`-Z dump-mir`, we should provide the
             // correct `ty::ParamEnv` to allow printing *all* constant values.
-            (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_param_types_or_consts() => {
+            (_, ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) if !ty.has_non_region_param() => {
                 let ct = tcx.lift(ct).unwrap();
                 let ty = tcx.lift(ty).unwrap();
                 if let Some(contents) = tcx.try_destructure_mir_constant(
@@ -2906,11 +2975,12 @@ impl Location {
 mod size_asserts {
     use super::*;
     use rustc_data_structures::static_assert_size;
-    // These are in alphabetical order, which is easy to maintain.
+    // tidy-alphabetical-start
     static_assert_size!(BasicBlockData<'_>, 144);
     static_assert_size!(LocalDecl<'_>, 56);
     static_assert_size!(Statement<'_>, 32);
     static_assert_size!(StatementKind<'_>, 16);
     static_assert_size!(Terminator<'_>, 112);
     static_assert_size!(TerminatorKind<'_>, 96);
+    // tidy-alphabetical-end
 }
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 21ae121e1..15a24aa4a 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -81,7 +81,7 @@ impl<'tcx> MonoItem<'tcx> {
             MonoItem::Fn(instance) => tcx.symbol_name(instance),
             MonoItem::Static(def_id) => tcx.symbol_name(Instance::mono(tcx, def_id)),
             MonoItem::GlobalAsm(item_id) => {
-                SymbolName::new(tcx, &format!("global_asm_{:?}", item_id.def_id))
+                SymbolName::new(tcx, &format!("global_asm_{:?}", item_id.owner_id))
             }
         }
     }
@@ -182,7 +182,7 @@ impl<'tcx> MonoItem<'tcx> {
         match *self {
             MonoItem::Fn(Instance { def, .. }) => def.def_id().as_local(),
             MonoItem::Static(def_id) => def_id.as_local(),
-            MonoItem::GlobalAsm(item_id) => Some(item_id.def_id),
+            MonoItem::GlobalAsm(item_id) => Some(item_id.owner_id.def_id),
         }
         .map(|def_id| tcx.def_span(def_id))
     }
@@ -373,7 +373,7 @@ impl<'tcx> CodegenUnit<'tcx> {
                         }
                     }
                     MonoItem::Static(def_id) => def_id.as_local().map(Idx::index),
-                    MonoItem::GlobalAsm(item_id) => Some(item_id.def_id.index()),
+                    MonoItem::GlobalAsm(item_id) => Some(item_id.owner_id.def_id.index()),
                 },
                 item.symbol_name(tcx),
             )
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 0b42137d4..05dcfba77 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -466,10 +466,9 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                     ty::ConstKind::Param(p) => format!("Param({})", p),
                     ty::ConstKind::Unevaluated(uv) => {
                         format!(
-                            "Unevaluated({}, {:?}, {:?})",
+                            "Unevaluated({}, {:?})",
                             self.tcx.def_path_str(uv.def.did),
                             uv.substs,
-                            uv.promoted,
                         )
                     }
                     ty::ConstKind::Value(val) => format!("Value({})", fmt_valtree(&val)),
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index d89efe2b3..efd7357af 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -392,16 +392,9 @@ pub enum ClosureOutlivesSubject<'tcx> {
     Region(ty::RegionVid),
 }
 
-/// The constituent parts of a type level constant of kind ADT or array.
-#[derive(Copy, Clone, Debug, HashStable)]
-pub struct DestructuredConst<'tcx> {
-    pub variant: Option<VariantIdx>,
-    pub fields: &'tcx [ty::Const<'tcx>],
-}
-
 /// The constituent parts of a mir constant of kind ADT or array.
 #[derive(Copy, Clone, Debug, HashStable)]
-pub struct DestructuredMirConstant<'tcx> {
+pub struct DestructuredConstant<'tcx> {
     pub variant: Option<VariantIdx>,
     pub fields: &'tcx [ConstantKind<'tcx>],
 }
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index c7d0283aa..85ef51f12 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -82,9 +82,10 @@ pub enum MirPhase {
     ///    access to. This occurs in generator bodies. Such locals do not behave like other locals,
     ///    because they eg may be aliased in surprising ways. Runtime MIR has no such special locals -
     ///    all generator bodies are lowered and so all places that look like locals really are locals.
-    ///  - Const prop lints: The lint pass which reports eg `200_u8 + 200_u8` as an error is run as a
-    ///    part of analysis to runtime MIR lowering. This means that transformations which may supress
-    ///    such errors may not run on analysis MIR.
+    ///
+    /// Also note that the lint pass which reports eg `200_u8 + 200_u8` as an error is run as a part
+    /// of analysis to runtime MIR lowering. To ensure lints are reported reliably, this means that
+    /// transformations which may supress such errors should not run on analysis MIR.
     Runtime(RuntimePhase),
 }
 
@@ -829,6 +830,9 @@ pub type AssertMessage<'tcx> = AssertKind<Operand<'tcx>>;
 ///    generator has more than one variant, the parent place's variant index must be set, indicating
 ///    which variant is being used. If it has just one variant, the variant index may or may not be
 ///    included - the single possible variant is inferred if it is not included.
+///  - [`OpaqueCast`](ProjectionElem::OpaqueCast): This projection changes the place's type to the
+///    given one, and makes no other changes. A `OpaqueCast` projection on any type other than an
+///    opaque type from the current crate is not well-formed.
 ///  - [`ConstantIndex`](ProjectionElem::ConstantIndex): Computes an offset in units of `T` into the
 ///    place as described in the documentation for the `ProjectionElem`. The resulting address is
 ///    the parent's address plus that offset, and the type is `T`. This is only legal if the parent
@@ -928,6 +932,10 @@ pub enum ProjectionElem<V, T> {
     ///
     /// The included Symbol is the name of the variant, used for printing MIR.
     Downcast(Option<Symbol>, VariantIdx),
+
+    /// Like an explicit cast from an opaque type to a concrete type, but without
+    /// requiring an intermediate variable.
+    OpaqueCast(T),
 }
 
 /// Alias for projections as they appear in places, where the base is a place
@@ -1141,8 +1149,12 @@ pub enum CastKind {
     Pointer(PointerCast),
     /// Cast into a dyn* object.
     DynStar,
-    /// Remaining unclassified casts.
-    Misc,
+    IntToInt,
+    FloatToInt,
+    FloatToFloat,
+    IntToFloat,
+    PtrToPtr,
+    FnPtrToPtr,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
@@ -1233,11 +1245,11 @@ pub enum BinOp {
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
 mod size_asserts {
     use super::*;
-    // These are in alphabetical order, which is easy to maintain.
-    #[cfg(not(bootstrap))]
+    // tidy-alphabetical-start
     static_assert_size!(AggregateKind<'_>, 40);
     static_assert_size!(Operand<'_>, 24);
     static_assert_size!(Place<'_>, 16);
     static_assert_size!(PlaceElem<'_>, 24);
     static_assert_size!(Rvalue<'_>, 40);
+    // tidy-alphabetical-end
 }
diff --git a/compiler/rustc_middle/src/mir/tcx.rs b/compiler/rustc_middle/src/mir/tcx.rs
index 405003156..fa3adafd4 100644
--- a/compiler/rustc_middle/src/mir/tcx.rs
+++ b/compiler/rustc_middle/src/mir/tcx.rs
@@ -4,7 +4,6 @@
  */
 
 use crate::mir::*;
-use crate::ty::subst::Subst;
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_hir as hir;
 use rustc_target::abi::VariantIdx;
@@ -57,7 +56,7 @@ impl<'tcx> PlaceTy<'tcx> {
     /// `PlaceElem`, where we can just use the `Ty` that is already
     /// stored inline on field projection elems.
     pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> {
-        self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty)
+        self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty, |_, ty| ty)
     }
 
     /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })`
@@ -71,6 +70,7 @@ impl<'tcx> PlaceTy<'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         elem: &ProjectionElem<V, T>,
         mut handle_field: impl FnMut(&Self, Field, T) -> Ty<'tcx>,
+        mut handle_opaque_cast: impl FnMut(&Self, T) -> Ty<'tcx>,
     ) -> PlaceTy<'tcx>
     where
         V: ::std::fmt::Debug,
@@ -109,6 +109,7 @@ impl<'tcx> PlaceTy<'tcx> {
                 PlaceTy { ty: self.ty, variant_index: Some(index) }
             }
             ProjectionElem::Field(f, fty) => PlaceTy::from_ty(handle_field(&self, f, fty)),
+            ProjectionElem::OpaqueCast(ty) => PlaceTy::from_ty(handle_opaque_cast(&self, ty)),
         };
         debug!("projection_ty self: {:?} elem: {:?} yields: {:?}", self, elem, answer);
         answer
diff --git a/compiler/rustc_middle/src/mir/type_foldable.rs b/compiler/rustc_middle/src/mir/type_foldable.rs
index 9d098c808..4c0974f86 100644
--- a/compiler/rustc_middle/src/mir/type_foldable.rs
+++ b/compiler/rustc_middle/src/mir/type_foldable.rs
@@ -26,6 +26,12 @@ TrivialTypeTraversalAndLiftImpls! {
     GeneratorSavedLocal,
 }
 
+TrivialTypeTraversalImpls! {
+    for <'tcx> {
+        ConstValue<'tcx>,
+    }
+}
+
 impl<'tcx> TypeFoldable<'tcx> for &'tcx [InlineAsmTemplatePiece] {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
         Ok(self)
@@ -49,25 +55,3 @@ impl<'tcx, R: Idx, C: Idx> TypeFoldable<'tcx> for BitMatrix<R, C> {
         Ok(self)
     }
 }
-
-impl<'tcx> TypeFoldable<'tcx> for ConstantKind<'tcx> {
-    #[inline(always)]
-    fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        folder.try_fold_mir_const(self)
-    }
-}
-
-impl<'tcx> TypeSuperFoldable<'tcx> for ConstantKind<'tcx> {
-    fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
-        self,
-        folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        match self {
-            ConstantKind::Ty(c) => Ok(ConstantKind::Ty(c.try_fold_with(folder)?)),
-            ConstantKind::Val(v, t) => Ok(ConstantKind::Val(v, t.try_fold_with(folder)?)),
-            ConstantKind::Unevaluated(uv, t) => {
-                Ok(ConstantKind::Unevaluated(uv.try_fold_with(folder)?, t.try_fold_with(folder)?))
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_middle/src/mir/type_visitable.rs b/compiler/rustc_middle/src/mir/type_visitable.rs
index be19bb486..e7cd497b2 100644
--- a/compiler/rustc_middle/src/mir/type_visitable.rs
+++ b/compiler/rustc_middle/src/mir/type_visitable.rs
@@ -7,22 +7,3 @@ impl<'tcx, R: Idx, C: Idx> TypeVisitable<'tcx> for BitMatrix<R, C> {
         ControlFlow::CONTINUE
     }
 }
-
-impl<'tcx> TypeVisitable<'tcx> for ConstantKind<'tcx> {
-    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        visitor.visit_mir_const(*self)
-    }
-}
-
-impl<'tcx> TypeSuperVisitable<'tcx> for ConstantKind<'tcx> {
-    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        match *self {
-            ConstantKind::Ty(c) => c.visit_with(visitor),
-            ConstantKind::Val(_, t) => t.visit_with(visitor),
-            ConstantKind::Unevaluated(uv, t) => {
-                uv.visit_with(visitor)?;
-                t.visit_with(visitor)
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index d9b24566b..ddcf3711b 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -1084,6 +1084,11 @@ macro_rules! visit_place_fns {
                     self.visit_ty(&mut new_ty, TyContext::Location(location));
                     if ty != new_ty { Some(PlaceElem::Field(field, new_ty)) } else { None }
                 }
+                PlaceElem::OpaqueCast(ty) => {
+                    let mut new_ty = ty;
+                    self.visit_ty(&mut new_ty, TyContext::Location(location));
+                    if ty != new_ty { Some(PlaceElem::OpaqueCast(new_ty)) } else { None }
+                }
                 PlaceElem::Deref
                 | PlaceElem::ConstantIndex { .. }
                 | PlaceElem::Subslice { .. }
@@ -1153,7 +1158,7 @@ macro_rules! visit_place_fns {
             location: Location,
         ) {
             match elem {
-                ProjectionElem::Field(_field, ty) => {
+                ProjectionElem::OpaqueCast(ty) | ProjectionElem::Field(_, ty) => {
                     self.visit_ty(ty, TyContext::Location(location));
                 }
                 ProjectionElem::Index(local) => {
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 4b336ea62..3d720f09b 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -4,6 +4,9 @@
 //! ["Queries: demand-driven compilation"](https://rustc-dev-guide.rust-lang.org/query.html).
 //! This chapter includes instructions for adding new queries.
 
+use crate::ty::{self, print::describe_as_module, TyCtxt};
+use rustc_span::def_id::LOCAL_CRATE;
+
 // Each of these queries corresponds to a function pointer field in the
 // `Providers` struct for requesting a value of that type, and a method
 // on `tcx: TyCtxt` (and `tcx.at(span)`) for doing that request in a way
@@ -17,19 +20,19 @@
 // as they will raise an fatal error on query cycles instead.
 rustc_queries! {
     query trigger_delay_span_bug(key: DefId) -> () {
-        desc { "trigger a delay span bug" }
+        desc { "triggering a delay span bug" }
     }
 
-    query resolutions(_: ()) -> &'tcx ty::ResolverOutputs {
+    query resolutions(_: ()) -> &'tcx ty::ResolverGlobalCtxt {
         eval_always
         no_hash
-        desc { "get the resolver outputs" }
+        desc { "getting the resolver outputs" }
     }
 
     query resolver_for_lowering(_: ()) -> &'tcx Steal<ty::ResolverAstLowering> {
         eval_always
         no_hash
-        desc { "get the resolver for lowering" }
+        desc { "getting the resolver for lowering" }
     }
 
     /// Return the span for a definition.
@@ -37,7 +40,7 @@ rustc_queries! {
     /// This span is meant for dep-tracking rather than diagnostics. It should not be used outside
     /// of rustc_middle::hir::source_map.
     query source_span(key: LocalDefId) -> Span {
-        desc { "get the source span" }
+        desc { "getting the source span" }
     }
 
     /// Represents crate as a whole (as distinct from the top-level crate module).
@@ -49,14 +52,14 @@ rustc_queries! {
     query hir_crate(key: ()) -> Crate<'tcx> {
         arena_cache
         eval_always
-        desc { "get the crate HIR" }
+        desc { "getting the crate HIR" }
     }
 
     /// All items in the crate.
     query hir_crate_items(_: ()) -> rustc_middle::hir::ModuleItems {
         arena_cache
         eval_always
-        desc { "get HIR crate items" }
+        desc { "getting HIR crate items" }
     }
 
     /// The items in a module.
@@ -65,7 +68,7 @@ rustc_queries! {
     /// Avoid calling this query directly.
     query hir_module_items(key: LocalDefId) -> rustc_middle::hir::ModuleItems {
         arena_cache
-        desc { |tcx| "HIR module items in `{}`", tcx.def_path_str(key.to_def_id()) }
+        desc { |tcx| "getting HIR module items in `{}`", tcx.def_path_str(key.to_def_id()) }
         cache_on_disk_if { true }
     }
 
@@ -73,8 +76,8 @@ rustc_queries! {
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
-    query hir_owner(key: LocalDefId) -> Option<crate::hir::Owner<'tcx>> {
-        desc { |tcx| "HIR owner of `{}`", tcx.def_path_str(key.to_def_id()) }
+    query hir_owner(key: hir::OwnerId) -> Option<crate::hir::Owner<'tcx>> {
+        desc { |tcx| "getting HIR owner of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// Gives access to the HIR ID for the given `LocalDefId` owner `key`.
@@ -82,31 +85,31 @@ rustc_queries! {
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
     query local_def_id_to_hir_id(key: LocalDefId) -> hir::HirId {
-        desc { |tcx| "HIR ID of `{}`", tcx.def_path_str(key.to_def_id()) }
+        desc { |tcx| "getting HIR ID of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// Gives access to the HIR node's parent for the HIR owner `key`.
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
-    query hir_owner_parent(key: LocalDefId) -> hir::HirId {
-        desc { |tcx| "HIR parent of `{}`", tcx.def_path_str(key.to_def_id()) }
+    query hir_owner_parent(key: hir::OwnerId) -> hir::HirId {
+        desc { |tcx| "getting HIR parent of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// Gives access to the HIR nodes and bodies inside the HIR owner `key`.
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
-    query hir_owner_nodes(key: LocalDefId) -> hir::MaybeOwner<&'tcx hir::OwnerNodes<'tcx>> {
-        desc { |tcx| "HIR owner items in `{}`", tcx.def_path_str(key.to_def_id()) }
+    query hir_owner_nodes(key: hir::OwnerId) -> hir::MaybeOwner<&'tcx hir::OwnerNodes<'tcx>> {
+        desc { |tcx| "getting HIR owner items in `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// Gives access to the HIR attributes inside the HIR owner `key`.
     ///
     /// This can be conveniently accessed by methods on `tcx.hir()`.
     /// Avoid calling this query directly.
-    query hir_attrs(key: LocalDefId) -> &'tcx hir::AttributeMap<'tcx> {
-        desc { |tcx| "HIR owner attributes in `{}`", tcx.def_path_str(key.to_def_id()) }
+    query hir_attrs(key: hir::OwnerId) -> &'tcx hir::AttributeMap<'tcx> {
+        desc { |tcx| "getting HIR owner attributes in `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// Computes the `DefId` of the corresponding const parameter in case the `key` is a
@@ -135,7 +138,7 @@ rustc_queries! {
     /// Given the def_id of a const-generic parameter, computes the associated default const
     /// parameter. e.g. `fn example<const N: usize=3>` called on `N` would return `3`.
     query const_param_default(param: DefId) -> ty::Const<'tcx> {
-        desc { |tcx| "compute const default for a given parameter `{}`", tcx.def_path_str(param)  }
+        desc { |tcx| "computing const default for a given parameter `{}`", tcx.def_path_str(param)  }
         cache_on_disk_if { param.is_local() }
         separate_provide_extern
     }
@@ -164,7 +167,7 @@ rustc_queries! {
     query collect_trait_impl_trait_tys(key: DefId)
         -> Result<&'tcx FxHashMap<DefId, Ty<'tcx>>, ErrorGuaranteed>
     {
-        desc { "compare an impl and trait method signature, inferring any hidden `impl Trait` types in the process" }
+        desc { "comparing an impl and trait method signature, inferring any hidden `impl Trait` types in the process" }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
@@ -274,19 +277,24 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query lint_levels(_: ()) -> LintLevelMap {
+    query shallow_lint_levels_on(key: hir::OwnerId) -> rustc_middle::lint::ShallowLintLevelMap {
+        eval_always // fetches `resolutions`
         arena_cache
-        eval_always
-        desc { "computing the lint levels for items in this crate" }
+        desc { |tcx| "looking up lint levels for `{}`", tcx.def_path_str(key.to_def_id()) }
+    }
+
+    query lint_expectations(_: ()) -> Vec<(LintExpectationId, LintExpectation)> {
+        arena_cache
+        desc { "computing `#[expect]`ed lints in this crate" }
     }
 
     query parent_module_from_def_id(key: LocalDefId) -> LocalDefId {
         eval_always
-        desc { |tcx| "parent module of `{}`", tcx.def_path_str(key.to_def_id()) }
+        desc { |tcx| "getting the parent module of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     query expn_that_defined(key: DefId) -> rustc_span::ExpnId {
-        desc { |tcx| "expansion that defined `{}`", tcx.def_path_str(key) }
+        desc { |tcx| "getting the expansion that defined `{}`", tcx.def_path_str(key) }
         separate_provide_extern
     }
 
@@ -296,6 +304,32 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    /// Checks whether a type is representable or infinitely sized
+    query representability(_: LocalDefId) -> rustc_middle::ty::Representability {
+        desc { "checking if `{}` is representable", tcx.def_path_str(key.to_def_id()) }
+        // infinitely sized types will cause a cycle
+        cycle_delay_bug
+        // we don't want recursive representability calls to be forced with
+        // incremental compilation because, if a cycle occurs, we need the
+        // entire cycle to be in memory for diagnostics
+        anon
+    }
+
+    /// An implementation detail for the `representability` query
+    query representability_adt_ty(_: Ty<'tcx>) -> rustc_middle::ty::Representability {
+        desc { "checking if `{}` is representable", key }
+        cycle_delay_bug
+        anon
+    }
+
+    /// Set of param indexes for type params that are in the type's representation
+    query params_in_repr(key: DefId) -> rustc_index::bit_set::BitSet<u32> {
+        desc { "finding type parameters in the representation" }
+        arena_cache
+        no_hash
+        separate_provide_extern
+    }
+
     /// Fetch the THIR for a given body. If typeck for that body failed, returns an empty `Thir`.
     query thir_body(key: ty::WithOptConstParam<LocalDefId>)
         -> Result<(&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId), ErrorGuaranteed>
@@ -349,7 +383,7 @@ rustc_queries! {
     /// See the README for the `mir` module for details.
     query mir_const(key: ty::WithOptConstParam<LocalDefId>) -> &'tcx Steal<mir::Body<'tcx>> {
         desc {
-            |tcx| "processing MIR for {}`{}`",
+            |tcx| "preparing {}`{}` for borrow checking",
             if key.const_param_did.is_some() { "the const argument " } else { "" },
             tcx.def_path_str(key.did.to_def_id()),
         }
@@ -361,7 +395,7 @@ rustc_queries! {
         key: DefId
     ) -> Result<Option<&'tcx [ty::abstract_const::Node<'tcx>]>, ErrorGuaranteed> {
         desc {
-            |tcx| "building an abstract representation for {}", tcx.def_path_str(key),
+            |tcx| "building an abstract representation for `{}`", tcx.def_path_str(key),
         }
         separate_provide_extern
     }
@@ -371,16 +405,16 @@ rustc_queries! {
     ) -> Result<Option<&'tcx [ty::abstract_const::Node<'tcx>]>, ErrorGuaranteed> {
         desc {
             |tcx|
-            "building an abstract representation for the const argument {}",
+            "building an abstract representation for the const argument `{}`",
             tcx.def_path_str(key.0.to_def_id()),
         }
     }
 
     query try_unify_abstract_consts(key:
-        ty::ParamEnvAnd<'tcx, (ty::Unevaluated<'tcx, ()>, ty::Unevaluated<'tcx, ()>
+        ty::ParamEnvAnd<'tcx, (ty::UnevaluatedConst<'tcx>, ty::UnevaluatedConst<'tcx>
     )>) -> bool {
         desc {
-            |tcx| "trying to unify the generic constants {} and {}",
+            |tcx| "trying to unify the generic constants `{}` and `{}`",
             tcx.def_path_str(key.value.0.def.did), tcx.def_path_str(key.value.1.def.did)
         }
     }
@@ -402,7 +436,7 @@ rustc_queries! {
 
     query mir_for_ctfe_of_const_arg(key: (LocalDefId, DefId)) -> &'tcx mir::Body<'tcx> {
         desc {
-            |tcx| "MIR for CTFE of the const argument `{}`",
+            |tcx| "caching MIR for CTFE of the const argument `{}`",
             tcx.def_path_str(key.0.to_def_id())
         }
     }
@@ -414,7 +448,7 @@ rustc_queries! {
         ) {
         no_hash
         desc {
-            |tcx| "processing {}`{}`",
+            |tcx| "processing MIR for {}`{}`",
             if key.const_param_did.is_some() { "the const argument " } else { "" },
             tcx.def_path_str(key.did.to_def_id()),
         }
@@ -425,7 +459,7 @@ rustc_queries! {
     ) -> Vec<rustc_span::Symbol> {
         arena_cache
         desc {
-            |tcx| "symbols for captures of closure `{}` in `{}`",
+            |tcx| "finding symbols for captures of closure `{}` in `{}`",
             tcx.def_path_str(key.1.to_def_id()),
             tcx.def_path_str(key.0.to_def_id())
         }
@@ -487,12 +521,12 @@ rustc_queries! {
         // queries). Making it anonymous avoids hashing the result, which
         // may save a bit of time.
         anon
-        desc { "erasing regions from `{:?}`", ty }
+        desc { "erasing regions from `{}`", ty }
     }
 
     query wasm_import_module_map(_: CrateNum) -> FxHashMap<DefId, String> {
         arena_cache
-        desc { "wasm import module map" }
+        desc { "getting wasm import module map" }
     }
 
     /// Maps from the `DefId` of an item (trait/struct/enum/fn) to the
@@ -582,16 +616,8 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    // The cycle error here should be reported as an error by `check_representable`.
-    // We consider the type as Sized in the meanwhile to avoid
-    // further errors (done in impl Value for AdtSizedConstraint).
-    // Use `cycle_delay_bug` to delay the cycle error here to be emitted later
-    // in case we accidentally otherwise don't emit an error.
-    query adt_sized_constraint(
-        key: DefId
-    ) -> AdtSizedConstraint<'tcx> {
+    query adt_sized_constraint(key: DefId) -> &'tcx [Ty<'tcx>] {
         desc { |tcx| "computing `Sized` constraints for `{}`", tcx.def_path_str(key) }
-        cycle_delay_bug
     }
 
     query adt_dtorck_constraint(
@@ -680,7 +706,7 @@ rustc_queries! {
     /// Collects the associated items defined on a trait or impl.
     query associated_items(key: DefId) -> ty::AssocItems<'tcx> {
         arena_cache
-        desc { |tcx| "collecting associated items of {}", tcx.def_path_str(key) }
+        desc { |tcx| "collecting associated items of `{}`", tcx.def_path_str(key) }
     }
 
     /// Maps from associated items on a trait to the corresponding associated
@@ -706,7 +732,7 @@ rustc_queries! {
     ///`{ trait_f: impl_f, trait_g: impl_g }`
     query impl_item_implementor_ids(impl_id: DefId) -> FxHashMap<DefId, DefId> {
         arena_cache
-        desc { |tcx| "comparing impl items against trait for {}", tcx.def_path_str(impl_id) }
+        desc { |tcx| "comparing impl items against trait for `{}`", tcx.def_path_str(impl_id) }
     }
 
     /// Given an `impl_id`, return the trait it implements.
@@ -778,7 +804,7 @@ rustc_queries! {
     /// Note that we've liberated the late bound regions of function signatures, so
     /// this can not be used to check whether these types are well formed.
     query assumed_wf_types(key: DefId) -> &'tcx ty::List<Ty<'tcx>> {
-        desc { |tcx| "computing the implied bounds of {}", tcx.def_path_str(key) }
+        desc { |tcx| "computing the implied bounds of `{}`", tcx.def_path_str(key) }
     }
 
     /// Computes the signature of the function.
@@ -827,7 +853,7 @@ rustc_queries! {
     }
 
     query check_liveness(key: DefId) {
-        desc { |tcx| "checking liveness of variables in {}", tcx.def_path_str(key) }
+        desc { |tcx| "checking liveness of variables in `{}`", tcx.def_path_str(key) }
     }
 
     /// Return the live symbols in the crate for dead code check.
@@ -839,7 +865,7 @@ rustc_queries! {
         FxHashMap<LocalDefId, Vec<(DefId, DefId)>>
     ) {
         arena_cache
-        desc { "find live symbols in crate" }
+        desc { "finding live symbols in crate" }
     }
 
     query check_mod_deathness(key: LocalDefId) -> () {
@@ -886,8 +912,8 @@ rustc_queries! {
         cache_on_disk_if { true }
     }
 
-    query used_trait_imports(key: LocalDefId) -> &'tcx FxHashSet<LocalDefId> {
-        desc { |tcx| "used_trait_imports `{}`", tcx.def_path_str(key.to_def_id()) }
+    query used_trait_imports(key: LocalDefId) -> &'tcx UnordSet<LocalDefId> {
+        desc { |tcx| "finding used_trait_imports `{}`", tcx.def_path_str(key.to_def_id()) }
         cache_on_disk_if { true }
     }
 
@@ -916,7 +942,7 @@ rustc_queries! {
     /// Not meant to be used directly outside of coherence.
     query crate_inherent_impls(k: ()) -> CrateInherentImpls {
         arena_cache
-        desc { "all inherent impls defined in crate" }
+        desc { "finding all inherent impls defined in crate" }
     }
 
     /// Checks all types in the crate for overlap in their inherent impls. Reports errors.
@@ -1003,8 +1029,10 @@ rustc_queries! {
 
     /// Tries to destructure an `mir::ConstantKind` ADT or array into its variant index
     /// and its field values.
-    query try_destructure_mir_constant(key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>) -> Option<mir::DestructuredMirConstant<'tcx>> {
-        desc { "destructuring mir constant"}
+    query try_destructure_mir_constant(
+        key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
+    ) -> Option<mir::DestructuredConstant<'tcx>> {
+        desc { "destructuring MIR constant"}
         remap_env_constness
     }
 
@@ -1013,12 +1041,12 @@ rustc_queries! {
     query deref_mir_constant(
         key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
     ) -> mir::ConstantKind<'tcx> {
-        desc { "dereferencing mir constant" }
+        desc { "dereferencing MIR constant" }
         remap_env_constness
     }
 
     query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> ConstValue<'tcx> {
-        desc { "get a &core::panic::Location referring to a span" }
+        desc { "getting a &core::panic::Location referring to a span" }
     }
 
     // FIXME get rid of this with valtrees
@@ -1037,10 +1065,10 @@ rustc_queries! {
         cache_on_disk_if { key.is_local() }
     }
 
-    /// Performs part of the privacy check and computes "access levels".
-    query privacy_access_levels(_: ()) -> &'tcx AccessLevels {
+    /// Performs part of the privacy check and computes effective visibilities.
+    query effective_visibilities(_: ()) -> &'tcx EffectiveVisibilities {
         eval_always
-        desc { "privacy access levels" }
+        desc { "checking effective visibilities" }
     }
     query check_private_in_public(_: ()) -> () {
         eval_always
@@ -1124,6 +1152,11 @@ rustc_queries! {
         desc { |tcx| "checking whether `{}` is `doc(hidden)`", tcx.def_path_str(def_id) }
     }
 
+    /// Determines whether an item is annotated with `doc(notable_trait)`.
+    query is_doc_notable_trait(def_id: DefId) -> bool {
+        desc { |tcx| "checking whether `{}` is `doc(notable_trait)`", tcx.def_path_str(def_id) }
+    }
+
     /// Returns the attributes on the item at `def_id`.
     ///
     /// Do not use this directly, use `tcx.get_attrs` instead.
@@ -1163,29 +1196,29 @@ rustc_queries! {
     }
 
     query is_ctfe_mir_available(key: DefId) -> bool {
-        desc { |tcx| "checking if item has ctfe mir available: `{}`", tcx.def_path_str(key) }
+        desc { |tcx| "checking if item has CTFE MIR available: `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
     query is_mir_available(key: DefId) -> bool {
-        desc { |tcx| "checking if item has mir available: `{}`", tcx.def_path_str(key) }
+        desc { |tcx| "checking if item has MIR available: `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
 
     query own_existential_vtable_entries(
-        key: ty::PolyExistentialTraitRef<'tcx>
+        key: DefId
     ) -> &'tcx [DefId] {
-        desc { |tcx| "finding all existential vtable entries for trait {}", tcx.def_path_str(key.def_id()) }
+        desc { |tcx| "finding all existential vtable entries for trait `{}`", tcx.def_path_str(key) }
     }
 
     query vtable_entries(key: ty::PolyTraitRef<'tcx>)
                         -> &'tcx [ty::VtblEntry<'tcx>] {
-        desc { |tcx| "finding all vtable entries for trait {}", tcx.def_path_str(key.def_id()) }
+        desc { |tcx| "finding all vtable entries for trait `{}`", tcx.def_path_str(key.def_id()) }
     }
 
-    query vtable_trait_upcasting_coercion_new_vptr_slot(key: (ty::Ty<'tcx>, ty::Ty<'tcx>)) -> Option<usize> {
-        desc { |tcx| "finding the slot within vtable for trait object {} vtable ptr during trait upcasting coercion from {} vtable",
+    query vtable_trait_upcasting_coercion_new_vptr_slot(key: (Ty<'tcx>, Ty<'tcx>)) -> Option<usize> {
+        desc { |tcx| "finding the slot within vtable for trait object `{}` vtable ptr during trait upcasting coercion from `{}` vtable",
             key.1, key.0 }
     }
 
@@ -1205,13 +1238,13 @@ rustc_queries! {
 
     /// Return all `impl` blocks in the current crate.
     query all_local_trait_impls(_: ()) -> &'tcx rustc_data_structures::fx::FxIndexMap<DefId, Vec<LocalDefId>> {
-        desc { "local trait impls" }
+        desc { "finding local trait impls" }
     }
 
     /// Given a trait `trait_id`, return all known `impl` blocks.
     query trait_impls_of(trait_id: DefId) -> ty::trait_def::TraitImpls {
         arena_cache
-        desc { |tcx| "trait impls of `{}`", tcx.def_path_str(trait_id) }
+        desc { |tcx| "finding trait impls of `{}`", tcx.def_path_str(trait_id) }
     }
 
     query specialization_graph_of(trait_id: DefId) -> specialization_graph::Graph {
@@ -1220,7 +1253,7 @@ rustc_queries! {
         cache_on_disk_if { true }
     }
     query object_safety_violations(trait_id: DefId) -> &'tcx [traits::ObjectSafetyViolation] {
-        desc { |tcx| "determine object safety of trait `{}`", tcx.def_path_str(trait_id) }
+        desc { |tcx| "determining object safety of trait `{}`", tcx.def_path_str(trait_id) }
     }
 
     /// Gets the ParameterEnvironment for a given item; this environment
@@ -1278,7 +1311,7 @@ rustc_queries! {
     /// correctly.
     query has_structural_eq_impls(ty: Ty<'tcx>) -> bool {
         desc {
-            "computing whether `{:?}` implements `PartialStructuralEq` and `StructuralEq`",
+            "computing whether `{}` implements `PartialStructuralEq` and `StructuralEq`",
             ty
         }
     }
@@ -1337,13 +1370,13 @@ rustc_queries! {
 
     query dylib_dependency_formats(_: CrateNum)
                                     -> &'tcx [(CrateNum, LinkagePreference)] {
-        desc { "dylib dependency formats of crate" }
+        desc { "getting dylib dependency formats of crate" }
         separate_provide_extern
     }
 
     query dependency_formats(_: ()) -> Lrc<crate::middle::dependency_format::Dependencies> {
         arena_cache
-        desc { "get the linkage format of all dependencies" }
+        desc { "getting the linkage format of all dependencies" }
     }
 
     query is_compiler_builtins(_: CrateNum) -> bool {
@@ -1365,31 +1398,31 @@ rustc_queries! {
     }
     query is_profiler_runtime(_: CrateNum) -> bool {
         fatal_cycle
-        desc { "query a crate is `#![profiler_runtime]`" }
+        desc { "checking if a crate is `#![profiler_runtime]`" }
         separate_provide_extern
     }
     query has_ffi_unwind_calls(key: LocalDefId) -> bool {
-        desc { |tcx| "check if `{}` contains FFI-unwind calls", tcx.def_path_str(key.to_def_id()) }
+        desc { |tcx| "checking if `{}` contains FFI-unwind calls", tcx.def_path_str(key.to_def_id()) }
         cache_on_disk_if { true }
     }
     query required_panic_strategy(_: CrateNum) -> Option<PanicStrategy> {
         fatal_cycle
-        desc { "query a crate's required panic strategy" }
+        desc { "getting a crate's required panic strategy" }
         separate_provide_extern
     }
     query panic_in_drop_strategy(_: CrateNum) -> PanicStrategy {
         fatal_cycle
-        desc { "query a crate's configured panic-in-drop strategy" }
+        desc { "getting a crate's configured panic-in-drop strategy" }
         separate_provide_extern
     }
     query is_no_builtins(_: CrateNum) -> bool {
         fatal_cycle
-        desc { "test whether a crate has `#![no_builtins]`" }
+        desc { "getting whether a crate has `#![no_builtins]`" }
         separate_provide_extern
     }
     query symbol_mangling_version(_: CrateNum) -> SymbolManglingVersion {
         fatal_cycle
-        desc { "query a crate's symbol mangling version" }
+        desc { "getting a crate's symbol mangling version" }
         separate_provide_extern
     }
 
@@ -1402,9 +1435,9 @@ rustc_queries! {
     query specializes(_: (DefId, DefId)) -> bool {
         desc { "computing whether impls specialize one another" }
     }
-    query in_scope_traits_map(_: LocalDefId)
+    query in_scope_traits_map(_: hir::OwnerId)
         -> Option<&'tcx FxHashMap<ItemLocalId, Box<[TraitCandidate]>>> {
-        desc { "traits in scope at a block" }
+        desc { "getting traits in scope at a block" }
     }
 
     query module_reexports(def_id: LocalDefId) -> Option<&'tcx [ModChild]> {
@@ -1417,7 +1450,7 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query check_well_formed(key: LocalDefId) -> () {
+    query check_well_formed(key: hir::OwnerId) -> () {
         desc { |tcx| "checking that `{}` is well-formed", tcx.def_path_str(key.to_def_id()) }
     }
 
@@ -1554,18 +1587,8 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query is_dllimport_foreign_item(def_id: DefId) -> bool {
-        desc { |tcx| "is_dllimport_foreign_item({})", tcx.def_path_str(def_id) }
-    }
-    query is_statically_included_foreign_item(def_id: DefId) -> bool {
-        desc { |tcx| "is_statically_included_foreign_item({})", tcx.def_path_str(def_id) }
-    }
-    query native_library_kind(def_id: DefId)
-        -> Option<NativeLibKind> {
-        desc { |tcx| "native_library_kind({})", tcx.def_path_str(def_id) }
-    }
     query native_library(def_id: DefId) -> Option<&'tcx NativeLib> {
-        desc { |tcx| "native_library({})", tcx.def_path_str(def_id) }
+        desc { |tcx| "getting the native library for `{}`", tcx.def_path_str(def_id) }
     }
 
     /// Does lifetime resolution, but does not descend into trait items. This
@@ -1584,7 +1607,7 @@ rustc_queries! {
         arena_cache
         desc { "resolving lifetimes" }
     }
-    query named_region_map(_: LocalDefId) ->
+    query named_region_map(_: hir::OwnerId) ->
         Option<&'tcx FxHashMap<ItemLocalId, Region>> {
         desc { "looking up a named region" }
     }
@@ -1600,7 +1623,7 @@ rustc_queries! {
         desc { "looking up lifetime defaults for generic parameter `{}`", tcx.def_path_str(key) }
         separate_provide_extern
     }
-    query late_bound_vars_map(_: LocalDefId)
+    query late_bound_vars_map(_: hir::OwnerId)
         -> Option<&'tcx FxHashMap<ItemLocalId, Vec<ty::BoundVariableKind>>> {
         desc { "looking up late bound vars" }
     }
@@ -1620,14 +1643,13 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    /// Computes the set of modules from which this type is visibly uninhabited.
-    /// To check whether a type is uninhabited at all (not just from a given module), you could
-    /// check whether the forest is empty.
-    query type_uninhabited_from(
-        key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
-    ) -> ty::inhabitedness::DefIdForest<'tcx> {
-        desc { "computing the inhabitedness of `{:?}`", key }
-        remap_env_constness
+    query inhabited_predicate_adt(key: DefId) -> ty::inhabitedness::InhabitedPredicate<'tcx> {
+        desc { "computing the uninhabited predicate of `{:?}`", key }
+    }
+
+    /// Do not call this query directly: invoke `Ty::inhabited_predicate` instead.
+    query inhabited_predicate_type(key: Ty<'tcx>) -> ty::inhabitedness::InhabitedPredicate<'tcx> {
+        desc { "computing the uninhabited predicate of `{}`", key }
     }
 
     query dep_kind(_: CrateNum) -> CrateDepKind {
@@ -1665,7 +1687,7 @@ rustc_queries! {
     }
     /// Whether the function is an intrinsic
     query is_intrinsic(def_id: DefId) -> bool {
-        desc { |tcx| "is_intrinsic({})", tcx.def_path_str(def_id) }
+        desc { |tcx| "checking whether `{}` is an intrinsic", tcx.def_path_str(def_id) }
         separate_provide_extern
     }
     /// Returns the lang items defined in another crate by loading it from metadata.
@@ -1732,12 +1754,12 @@ rustc_queries! {
     /// is marked as a private dependency
     query is_private_dep(c: CrateNum) -> bool {
         eval_always
-        desc { "check whether crate {} is a private dependency", c }
+        desc { "checking whether crate `{}` is a private dependency", c }
         separate_provide_extern
     }
     query allocator_kind(_: ()) -> Option<AllocatorKind> {
         eval_always
-        desc { "allocator kind for the current crate" }
+        desc { "getting the allocator kind for the current crate" }
     }
 
     query upvars_mentioned(def_id: DefId) -> Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>> {
@@ -1750,7 +1772,7 @@ rustc_queries! {
         desc { "looking up all possibly unused extern crates" }
     }
     query names_imported_by_glob_use(def_id: LocalDefId) -> &'tcx FxHashSet<Symbol> {
-        desc { |tcx| "names_imported_by_glob_use for `{}`", tcx.def_path_str(def_id.to_def_id()) }
+        desc { |tcx| "finding names imported by glob use for `{}`", tcx.def_path_str(def_id.to_def_id()) }
     }
 
     query stability_index(_: ()) -> stability::Index {
@@ -1776,7 +1798,7 @@ rustc_queries! {
     ///   correspond to a publicly visible symbol in `cnum` machine code.
     /// - The `exported_symbols` sets of different crates do not intersect.
     query exported_symbols(cnum: CrateNum) -> &'tcx [(ExportedSymbol<'tcx>, SymbolExportInfo)] {
-        desc { "exported_symbols" }
+        desc { "collecting exported symbols for crate `{}`", cnum}
         cache_on_disk_if { *cnum == LOCAL_CRATE }
         separate_provide_extern
     }
@@ -1785,6 +1807,7 @@ rustc_queries! {
         eval_always
         desc { "collect_and_partition_mono_items" }
     }
+
     query is_codegened_item(def_id: DefId) -> bool {
         desc { |tcx| "determining whether `{}` needs codegen", tcx.def_path_str(def_id) }
     }
@@ -1792,12 +1815,13 @@ rustc_queries! {
     /// All items participating in code generation together with items inlined into them.
     query codegened_and_inlined_items(_: ()) -> &'tcx DefIdSet {
         eval_always
-       desc { "codegened_and_inlined_items" }
+        desc { "collecting codegened and inlined items" }
     }
 
-    query codegen_unit(_: Symbol) -> &'tcx CodegenUnit<'tcx> {
-        desc { "codegen_unit" }
+    query codegen_unit(sym: Symbol) -> &'tcx CodegenUnit<'tcx> {
+        desc { "getting codegen unit `{sym}`" }
     }
+
     query unused_generic_params(key: ty::InstanceDef<'tcx>) -> FiniteBitSet<u32> {
         cache_on_disk_if { key.def_id().is_local() }
         desc {
@@ -1806,6 +1830,7 @@ rustc_queries! {
         }
         separate_provide_extern
     }
+
     query backend_optimization_level(_: ()) -> OptLevel {
         desc { "optimization level used by backend" }
     }
@@ -1816,7 +1841,7 @@ rustc_queries! {
     /// has been destroyed.
     query output_filenames(_: ()) -> &'tcx Arc<OutputFilenames> {
         eval_always
-        desc { "output_filenames" }
+        desc { "getting output filenames" }
     }
 
     /// Do not call this query directly: invoke `normalize` instead.
@@ -1826,7 +1851,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, NormalizationResult<'tcx>>>,
         NoSolution,
     > {
-        desc { "normalizing `{:?}`", goal }
+        desc { "normalizing `{}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1838,21 +1863,13 @@ rustc_queries! {
         remap_env_constness
     }
 
-    /// Do not call this query directly: invoke `try_normalize_erasing_regions` instead.
-    query try_normalize_mir_const_after_erasing_regions(
-        goal: ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
-    ) -> Result<mir::ConstantKind<'tcx>, NoSolution> {
-        desc { "normalizing `{}`", goal.value }
-        remap_env_constness
-    }
-
     query implied_outlives_bounds(
         goal: CanonicalTyGoal<'tcx>
     ) -> Result<
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>,
         NoSolution,
     > {
-        desc { "computing implied outlives bounds for `{:?}`", goal }
+        desc { "computing implied outlives bounds for `{}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1864,7 +1881,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, DropckOutlivesResult<'tcx>>>,
         NoSolution,
     > {
-        desc { "computing dropck types for `{:?}`", goal }
+        desc { "computing dropck types for `{}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1892,7 +1909,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>,
         NoSolution,
     > {
-        desc { "evaluating `type_op_ascribe_user_type` `{:?}`", goal }
+        desc { "evaluating `type_op_ascribe_user_type` `{:?}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1903,7 +1920,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>,
         NoSolution,
     > {
-        desc { "evaluating `type_op_eq` `{:?}`", goal }
+        desc { "evaluating `type_op_eq` `{:?}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1914,7 +1931,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>,
         NoSolution,
     > {
-        desc { "evaluating `type_op_subtype` `{:?}`", goal }
+        desc { "evaluating `type_op_subtype` `{:?}`", goal.value.value }
         remap_env_constness
     }
 
@@ -1925,7 +1942,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ()>>,
         NoSolution,
     > {
-        desc { "evaluating `type_op_prove_predicate` `{:?}`", goal }
+        desc { "evaluating `type_op_prove_predicate` `{:?}`", goal.value.value }
     }
 
     /// Do not call this query directly: part of the `Normalize` type-op
@@ -1935,7 +1952,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Ty<'tcx>>>,
         NoSolution,
     > {
-        desc { "normalizing `{:?}`", goal }
+        desc { "normalizing `{}`", goal.value.value.value }
         remap_env_constness
     }
 
@@ -1946,7 +1963,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::Predicate<'tcx>>>,
         NoSolution,
     > {
-        desc { "normalizing `{:?}`", goal }
+        desc { "normalizing `{:?}`", goal.value.value.value }
         remap_env_constness
     }
 
@@ -1957,7 +1974,7 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::PolyFnSig<'tcx>>>,
         NoSolution,
     > {
-        desc { "normalizing `{:?}`", goal }
+        desc { "normalizing `{:?}`", goal.value.value.value }
         remap_env_constness
     }
 
@@ -1968,20 +1985,20 @@ rustc_queries! {
         &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, ty::FnSig<'tcx>>>,
         NoSolution,
     > {
-        desc { "normalizing `{:?}`", goal }
+        desc { "normalizing `{:?}`", goal.value.value.value }
         remap_env_constness
     }
 
     query subst_and_check_impossible_predicates(key: (DefId, SubstsRef<'tcx>)) -> bool {
         desc { |tcx|
-            "impossible substituted predicates:`{}`",
+            "checking impossible substituted predicates: `{}`",
             tcx.def_path_str(key.0)
         }
     }
 
     query is_impossible_method(key: (DefId, DefId)) -> bool {
         desc { |tcx|
-            "checking if {} is impossible to call within {}",
+            "checking if `{}` is impossible to call within `{}`",
             tcx.def_path_str(key.1),
             tcx.def_path_str(key.0),
         }
@@ -1990,7 +2007,7 @@ rustc_queries! {
     query method_autoderef_steps(
         goal: CanonicalTyGoal<'tcx>
     ) -> MethodAutoderefStepsResult<'tcx> {
-        desc { "computing autoderef types for `{:?}`", goal }
+        desc { "computing autoderef types for `{}`", goal.value.value }
         remap_env_constness
     }
 
@@ -2038,7 +2055,7 @@ rustc_queries! {
     }
 
     query normalize_opaque_types(key: &'tcx ty::List<ty::Predicate<'tcx>>) -> &'tcx ty::List<ty::Predicate<'tcx>> {
-        desc { "normalizing opaque types in {:?}", key }
+        desc { "normalizing opaque types in `{:?}`", key }
     }
 
     /// Checks whether a type is definitely uninhabited. This is
@@ -2048,7 +2065,7 @@ rustc_queries! {
     /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
     /// size, to account for partial initialisation. See #49298 for details.)
     query conservative_is_privately_uninhabited(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
-        desc { "conservatively checking if {:?} is privately uninhabited", key }
+        desc { "conservatively checking if `{}` is privately uninhabited", key.value }
         remap_env_constness
     }
 
@@ -2068,7 +2085,7 @@ rustc_queries! {
         arena_cache
         eval_always
         no_hash
-        desc { "performing HIR wf-checking for predicate {:?} at item {:?}", key.0, key.1 }
+        desc { "performing HIR wf-checking for predicate `{:?}` at item `{:?}`", key.0, key.1 }
     }
 
 
@@ -2087,10 +2104,21 @@ rustc_queries! {
     }
 
     query permits_uninit_init(key: TyAndLayout<'tcx>) -> bool {
-        desc { "checking to see if {:?} permits being left uninit", key.ty }
+        desc { "checking to see if `{}` permits being left uninit", key.ty }
     }
 
     query permits_zero_init(key: TyAndLayout<'tcx>) -> bool {
-        desc { "checking to see if {:?} permits being left zeroed", key.ty }
+        desc { "checking to see if `{}` permits being left zeroed", key.ty }
+    }
+
+    query compare_assoc_const_impl_item_with_trait_item(
+        key: (LocalDefId, DefId)
+    ) -> Result<(), ErrorGuaranteed> {
+        desc { |tcx| "checking assoc const `{}` has the same type as trait item", tcx.def_path_str(key.0.to_def_id()) }
+    }
+
+    query deduced_param_attrs(def_id: DefId) -> &'tcx [ty::DeducedParamAttrs] {
+        desc { |tcx| "deducing parameter attributes for {}", tcx.def_path_str(def_id) }
+        separate_provide_extern
     }
 }
diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs
index 86b415050..ea7a507d7 100644
--- a/compiler/rustc_middle/src/thir.rs
+++ b/compiler/rustc_middle/src/thir.rs
@@ -203,7 +203,7 @@ pub enum StmtKind<'tcx> {
         /// `let pat: ty = <INIT>`
         initializer: Option<ExprId>,
 
-        /// `let pat: ty = <INIT> else { <ELSE> }
+        /// `let pat: ty = <INIT> else { <ELSE> }`
         else_block: Option<BlockId>,
 
         /// The lint level for this `let` statement.
@@ -848,16 +848,13 @@ impl<'tcx> fmt::Display for Pat<'tcx> {
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
 mod size_asserts {
     use super::*;
-    // These are in alphabetical order, which is easy to maintain.
+    // tidy-alphabetical-start
     static_assert_size!(Block, 56);
     static_assert_size!(Expr<'_>, 64);
     static_assert_size!(ExprKind<'_>, 40);
-    #[cfg(not(bootstrap))]
     static_assert_size!(Pat<'_>, 72);
-    #[cfg(not(bootstrap))]
     static_assert_size!(PatKind<'_>, 56);
-    #[cfg(not(bootstrap))]
     static_assert_size!(Stmt<'_>, 48);
-    #[cfg(not(bootstrap))]
     static_assert_size!(StmtKind<'_>, 40);
+    // tidy-alphabetical-end
 }
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 68a7af0b8..e73d44bbb 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -598,11 +598,6 @@ pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
 ///     // type parameters, ImplSource will carry resolutions for those as well:
 ///     concrete.clone(); // ImplSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])])
 ///
-///     // Case A: ImplSource points at a specific impl. Only possible when
-///     // type is concretely known. If the impl itself has bounded
-///     // type parameters, ImplSource will carry resolutions for those as well:
-///     concrete.clone(); // ImplSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])])
-///
 ///     // Case B: ImplSource must be provided by caller. This applies when
 ///     // type is a type parameter.
 ///     param.clone();    // ImplSource::Param
@@ -664,10 +659,6 @@ pub enum ImplSource<'tcx, N> {
 
     /// ImplSource for a `const Drop` implementation.
     ConstDestruct(ImplSourceConstDestructData<N>),
-
-    /// ImplSource for a `std::marker::Tuple` implementation.
-    /// This has no nested predicates ever, so no data.
-    Tuple,
 }
 
 impl<'tcx, N> ImplSource<'tcx, N> {
@@ -682,8 +673,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::Object(d) => d.nested,
             ImplSource::FnPointer(d) => d.nested,
             ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData)
-            | ImplSource::Tuple => Vec::new(),
+            | ImplSource::Pointee(ImplSourcePointeeData) => vec![],
             ImplSource::TraitAlias(d) => d.nested,
             ImplSource::TraitUpcasting(d) => d.nested,
             ImplSource::ConstDestruct(i) => i.nested,
@@ -701,8 +691,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::Object(d) => &d.nested,
             ImplSource::FnPointer(d) => &d.nested,
             ImplSource::DiscriminantKind(ImplSourceDiscriminantKindData)
-            | ImplSource::Pointee(ImplSourcePointeeData)
-            | ImplSource::Tuple => &[],
+            | ImplSource::Pointee(ImplSourcePointeeData) => &[],
             ImplSource::TraitAlias(d) => &d.nested,
             ImplSource::TraitUpcasting(d) => &d.nested,
             ImplSource::ConstDestruct(i) => &i.nested,
@@ -769,7 +758,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                     nested: i.nested.into_iter().map(f).collect(),
                 })
             }
-            ImplSource::Tuple => ImplSource::Tuple,
         }
     }
 }
diff --git a/compiler/rustc_middle/src/traits/query.rs b/compiler/rustc_middle/src/traits/query.rs
index 0e6cacb9f..fb152b63f 100644
--- a/compiler/rustc_middle/src/traits/query.rs
+++ b/compiler/rustc_middle/src/traits/query.rs
@@ -8,8 +8,9 @@
 use crate::error::DropCheckOverflow;
 use crate::infer::canonical::{Canonical, QueryResponse};
 use crate::ty::error::TypeError;
-use crate::ty::subst::GenericArg;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, Ty, TyCtxt};
+use rustc_hir::def_id::DefId;
 use rustc_span::source_map::Span;
 use std::iter::FromIterator;
 
@@ -219,4 +220,5 @@ pub enum OutlivesBound<'tcx> {
     RegionSubRegion(ty::Region<'tcx>, ty::Region<'tcx>),
     RegionSubParam(ty::Region<'tcx>, ty::ParamTy),
     RegionSubProjection(ty::Region<'tcx>, ty::ProjectionTy<'tcx>),
+    RegionSubOpaque(ty::Region<'tcx>, DefId, SubstsRef<'tcx>),
 }
diff --git a/compiler/rustc_middle/src/traits/select.rs b/compiler/rustc_middle/src/traits/select.rs
index 53af3e905..85ead3171 100644
--- a/compiler/rustc_middle/src/traits/select.rs
+++ b/compiler/rustc_middle/src/traits/select.rs
@@ -115,12 +115,13 @@ pub enum SelectionCandidate<'tcx> {
 
     ParamCandidate(ty::PolyTraitPredicate<'tcx>),
     ImplCandidate(DefId),
-    AutoImplCandidate(DefId),
+    AutoImplCandidate,
 
     /// This is a trait matching with a projected type as `Self`, and we found
     /// an applicable bound in the trait definition. The `usize` is an index
-    /// into the list returned by `tcx.item_bounds`.
-    ProjectionCandidate(usize),
+    /// into the list returned by `tcx.item_bounds`. The constness is the
+    /// constness of the bound in the trait.
+    ProjectionCandidate(usize, ty::BoundConstness),
 
     /// Implementation of a `Fn`-family trait by one of the anonymous types
     /// generated for an `||` expression.
@@ -142,7 +143,7 @@ pub enum SelectionCandidate<'tcx> {
     /// Builtin implementation of `Pointee`.
     PointeeCandidate,
 
-    TraitAliasCandidate(DefId),
+    TraitAliasCandidate,
 
     /// Matching `dyn Trait` with a supertrait of `Trait`. The index is the
     /// position in the iterator returned by
@@ -160,9 +161,6 @@ pub enum SelectionCandidate<'tcx> {
 
     /// Implementation of `const Destruct`, optionally from a custom `impl const Drop`.
     ConstDestructCandidate(Option<DefId>),
-
-    /// Witnesses the fact that a type is a tuple.
-    TupleCandidate,
 }
 
 /// The result of trait evaluation. The order is important
diff --git a/compiler/rustc_middle/src/traits/structural_impls.rs b/compiler/rustc_middle/src/traits/structural_impls.rs
index c526344e1..7fbd57ac7 100644
--- a/compiler/rustc_middle/src/traits/structural_impls.rs
+++ b/compiler/rustc_middle/src/traits/structural_impls.rs
@@ -34,8 +34,6 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
             super::ImplSource::TraitUpcasting(ref d) => write!(f, "{:?}", d),
 
             super::ImplSource::ConstDestruct(ref d) => write!(f, "{:?}", d),
-
-            super::ImplSource::Tuple => write!(f, "ImplSource::Tuple"),
         }
     }
 }
diff --git a/compiler/rustc_middle/src/ty/abstract_const.rs b/compiler/rustc_middle/src/ty/abstract_const.rs
index 8f79b4705..1aa4df778 100644
--- a/compiler/rustc_middle/src/ty/abstract_const.rs
+++ b/compiler/rustc_middle/src/ty/abstract_const.rs
@@ -1,7 +1,7 @@
 //! A subset of a mir body used for const evaluatability checking.
 use crate::mir;
 use crate::ty::visit::TypeVisitable;
-use crate::ty::{self, subst::Subst, DelaySpanBugEmitted, EarlyBinder, SubstsRef, Ty, TyCtxt};
+use crate::ty::{self, DelaySpanBugEmitted, EarlyBinder, SubstsRef, Ty, TyCtxt};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use std::cmp;
@@ -30,7 +30,7 @@ pub struct AbstractConst<'tcx> {
 impl<'tcx> AbstractConst<'tcx> {
     pub fn new(
         tcx: TyCtxt<'tcx>,
-        uv: ty::Unevaluated<'tcx, ()>,
+        uv: ty::UnevaluatedConst<'tcx>,
     ) -> Result<Option<AbstractConst<'tcx>>, ErrorGuaranteed> {
         let inner = tcx.thir_abstract_const_opt_const_arg(uv.def)?;
         debug!("AbstractConst::new({:?}) = {:?}", uv, inner);
@@ -71,16 +71,16 @@ impl<'tcx> AbstractConst<'tcx> {
         walk_abstract_const::<!, _>(tcx, self, |node| {
             match node.root(tcx) {
                 Node::Leaf(leaf) => {
-                    if leaf.has_infer_types_or_consts() {
+                    if leaf.has_non_region_infer() {
                         failure_kind = FailureKind::MentionsInfer;
-                    } else if leaf.has_param_types_or_consts() {
+                    } else if leaf.has_non_region_param() {
                         failure_kind = cmp::min(failure_kind, FailureKind::MentionsParam);
                     }
                 }
                 Node::Cast(_, _, ty) => {
-                    if ty.has_infer_types_or_consts() {
+                    if ty.has_non_region_infer() {
                         failure_kind = FailureKind::MentionsInfer;
-                    } else if ty.has_param_types_or_consts() {
+                    } else if ty.has_non_region_param() {
                         failure_kind = cmp::min(failure_kind, FailureKind::MentionsParam);
                     }
                 }
diff --git a/compiler/rustc_middle/src/ty/adjustment.rs b/compiler/rustc_middle/src/ty/adjustment.rs
index b809f1767..4682ac96b 100644
--- a/compiler/rustc_middle/src/ty/adjustment.rs
+++ b/compiler/rustc_middle/src/ty/adjustment.rs
@@ -101,6 +101,9 @@ pub enum Adjust<'tcx> {
     Borrow(AutoBorrow<'tcx>),
 
     Pointer(PointerCast),
+
+    /// Cast into a dyn* object.
+    DynStar,
 }
 
 /// An overloaded autoderef step, representing a `Deref(Mut)::deref(_mut)`
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index 2e596b275..b0a2412ab 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -26,9 +26,6 @@ use super::{
     Destructor, FieldDef, GenericPredicates, ReprOptions, Ty, TyCtxt, VariantDef, VariantDiscr,
 };
 
-#[derive(Copy, Clone, HashStable, Debug)]
-pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
-
 bitflags! {
     #[derive(HashStable, TyEncodable, TyDecodable)]
     pub struct AdtFlags: u32 {
@@ -332,13 +329,13 @@ impl<'tcx> AdtDef<'tcx> {
         self.flags().contains(AdtFlags::IS_PHANTOM_DATA)
     }
 
-    /// Returns `true` if this is Box<T>.
+    /// Returns `true` if this is `Box<T>`.
     #[inline]
     pub fn is_box(self) -> bool {
         self.flags().contains(AdtFlags::IS_BOX)
     }
 
-    /// Returns `true` if this is UnsafeCell<T>.
+    /// Returns `true` if this is `UnsafeCell<T>`.
     #[inline]
     pub fn is_unsafe_cell(self) -> bool {
         self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
@@ -438,7 +435,8 @@ impl<'tcx> AdtDef<'tcx> {
             | Res::Def(DefKind::Union, _)
             | Res::Def(DefKind::TyAlias, _)
             | Res::Def(DefKind::AssocTy, _)
-            | Res::SelfTy { .. }
+            | Res::SelfTyParam { .. }
+            | Res::SelfTyAlias { .. }
             | Res::SelfCtor(..) => self.non_enum_variant(),
             _ => bug!("unexpected res {:?} in variant_of_res", res),
         }
@@ -457,11 +455,9 @@ impl<'tcx> AdtDef<'tcx> {
                     Some(Discr { val: b, ty })
                 } else {
                     info!("invalid enum discriminant: {:#?}", val);
-                    crate::mir::interpret::struct_error(
-                        tcx.at(tcx.def_span(expr_did)),
-                        "constant evaluation of enum discriminant resulted in non-integer",
-                    )
-                    .emit();
+                    tcx.sess.emit_err(crate::error::ConstEvalNonIntError {
+                        span: tcx.def_span(expr_did),
+                    });
                     None
                 }
             }
@@ -564,6 +560,13 @@ impl<'tcx> AdtDef<'tcx> {
     /// Due to normalization being eager, this applies even if
     /// the associated type is behind a pointer (e.g., issue #31299).
     pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> ty::EarlyBinder<&'tcx [Ty<'tcx>]> {
-        ty::EarlyBinder(tcx.adt_sized_constraint(self.did()).0)
+        ty::EarlyBinder(tcx.adt_sized_constraint(self.did()))
     }
 }
+
+#[derive(Clone, Copy, Debug)]
+#[derive(HashStable)]
+pub enum Representability {
+    Representable,
+    Infinite,
+}
diff --git a/compiler/rustc_middle/src/ty/cast.rs b/compiler/rustc_middle/src/ty/cast.rs
index 981e2d3b6..e65585955 100644
--- a/compiler/rustc_middle/src/ty/cast.rs
+++ b/compiler/rustc_middle/src/ty/cast.rs
@@ -2,6 +2,7 @@
 // typeck and codegen.
 
 use crate::ty::{self, Ty};
+use rustc_middle::mir;
 
 use rustc_macros::HashStable;
 
@@ -38,7 +39,7 @@ pub enum CastTy<'tcx> {
 }
 
 /// Cast Kind. See [RFC 401](https://rust-lang.github.io/rfcs/0401-coercions.html)
-/// (or librustc_typeck/check/cast.rs).
+/// (or rustc_hir_analysis/check/cast.rs).
 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum CastKind {
     CoercionCast,
@@ -75,3 +76,28 @@ impl<'tcx> CastTy<'tcx> {
         }
     }
 }
+
+/// Returns `mir::CastKind` from the given parameters.
+pub fn mir_cast_kind<'tcx>(from_ty: Ty<'tcx>, cast_ty: Ty<'tcx>) -> mir::CastKind {
+    let from = CastTy::from_ty(from_ty);
+    let cast = CastTy::from_ty(cast_ty);
+    let cast_kind = match (from, cast) {
+        (Some(CastTy::Ptr(_) | CastTy::FnPtr), Some(CastTy::Int(_))) => {
+            mir::CastKind::PointerExposeAddress
+        }
+        (Some(CastTy::Int(_)), Some(CastTy::Ptr(_))) => mir::CastKind::PointerFromExposedAddress,
+        (_, Some(CastTy::DynStar)) => mir::CastKind::DynStar,
+        (Some(CastTy::Int(_)), Some(CastTy::Int(_))) => mir::CastKind::IntToInt,
+        (Some(CastTy::FnPtr), Some(CastTy::Ptr(_))) => mir::CastKind::FnPtrToPtr,
+
+        (Some(CastTy::Float), Some(CastTy::Int(_))) => mir::CastKind::FloatToInt,
+        (Some(CastTy::Int(_)), Some(CastTy::Float)) => mir::CastKind::IntToFloat,
+        (Some(CastTy::Float), Some(CastTy::Float)) => mir::CastKind::FloatToFloat,
+        (Some(CastTy::Ptr(_)), Some(CastTy::Ptr(_))) => mir::CastKind::PtrToPtr,
+
+        (_, _) => {
+            bug!("Attempting to cast non-castable types {:?} and {:?}", from_ty, cast_ty)
+        }
+    };
+    cast_kind
+}
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 51137c526..14ec88b7e 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -455,6 +455,7 @@ impl_arena_copy_decoder! {<'tcx>
     rustc_span::def_id::DefId,
     rustc_span::def_id::LocalDefId,
     (rustc_middle::middle::exported_symbols::ExportedSymbol<'tcx>, rustc_middle::middle::exported_symbols::SymbolExportInfo),
+    ty::DeducedParamAttrs,
 }
 
 #[macro_export]
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index 339ff4d35..f998e6083 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -1,9 +1,6 @@
 use crate::mir::interpret::LitToConstInput;
 use crate::mir::ConstantKind;
-use crate::ty::{
-    self, InlineConstSubsts, InlineConstSubstsParts, InternalSubsts, ParamEnv, ParamEnvAnd, Ty,
-    TyCtxt, TypeVisitable,
-};
+use crate::ty::{self, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_data_structures::intern::Interned;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
@@ -81,10 +78,9 @@ impl<'tcx> Const<'tcx> {
         match Self::try_eval_lit_or_param(tcx, ty, expr) {
             Some(v) => v,
             None => tcx.mk_const(ty::ConstS {
-                kind: ty::ConstKind::Unevaluated(ty::Unevaluated {
+                kind: ty::ConstKind::Unevaluated(ty::UnevaluatedConst {
                     def: def.to_global(),
                     substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
-                    promoted: (),
                 }),
                 ty,
             }),
@@ -151,46 +147,6 @@ impl<'tcx> Const<'tcx> {
         }
     }
 
-    pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
-        debug!("Const::from_inline_const(def_id={:?})", def_id);
-
-        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-
-        let body_id = match tcx.hir().get(hir_id) {
-            hir::Node::AnonConst(ac) => ac.body,
-            _ => span_bug!(
-                tcx.def_span(def_id.to_def_id()),
-                "from_inline_const can only process anonymous constants"
-            ),
-        };
-
-        let expr = &tcx.hir().body(body_id).value;
-
-        let ty = tcx.typeck(def_id).node_type(hir_id);
-
-        let ret = match Self::try_eval_lit_or_param(tcx, ty, expr) {
-            Some(v) => v,
-            None => {
-                let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
-                let parent_substs =
-                    tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
-                let substs =
-                    InlineConstSubsts::new(tcx, InlineConstSubstsParts { parent_substs, ty })
-                        .substs;
-                tcx.mk_const(ty::ConstS {
-                    kind: ty::ConstKind::Unevaluated(ty::Unevaluated {
-                        def: ty::WithOptConstParam::unknown(def_id).to_global(),
-                        substs,
-                        promoted: (),
-                    }),
-                    ty,
-                })
-            }
-        };
-        debug_assert!(!ret.has_free_regions());
-        ret
-    }
-
     /// Interns the given value as a constant.
     #[inline]
     pub fn from_value(tcx: TyCtxt<'tcx>, val: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Self {
@@ -307,6 +263,10 @@ impl<'tcx> Const<'tcx> {
         self.try_eval_usize(tcx, param_env)
             .unwrap_or_else(|| bug!("expected usize, got {:#?}", self))
     }
+
+    pub fn is_ct_infer(self) -> bool {
+        matches!(self.kind(), ty::ConstKind::Infer(_))
+    }
 }
 
 pub fn const_param_default<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Const<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/consts/kind.rs b/compiler/rustc_middle/src/ty/consts/kind.rs
index 455015280..4ab761e07 100644
--- a/compiler/rustc_middle/src/ty/consts/kind.rs
+++ b/compiler/rustc_middle/src/ty/consts/kind.rs
@@ -1,10 +1,11 @@
 use std::convert::TryInto;
 
+use crate::mir;
 use crate::mir::interpret::{AllocId, ConstValue, Scalar};
-use crate::mir::Promoted;
 use crate::ty::subst::{InternalSubsts, SubstsRef};
 use crate::ty::ParamEnv;
 use crate::ty::{self, TyCtxt, TypeVisitable};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
@@ -12,40 +13,34 @@ use rustc_target::abi::Size;
 
 use super::ScalarInt;
 
-/// An unevaluated, potentially generic, constant.
+/// An unevaluated (potentially generic) constant used in the type-system.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Lift)]
-#[derive(Hash, HashStable)]
-pub struct Unevaluated<'tcx, P = Option<Promoted>> {
+#[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
+pub struct UnevaluatedConst<'tcx> {
     pub def: ty::WithOptConstParam<DefId>,
     pub substs: SubstsRef<'tcx>,
-    pub promoted: P,
 }
 
-impl rustc_errors::IntoDiagnosticArg for Unevaluated<'_> {
+impl rustc_errors::IntoDiagnosticArg for UnevaluatedConst<'_> {
     fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
         format!("{:?}", self).into_diagnostic_arg()
     }
 }
 
-impl<'tcx> Unevaluated<'tcx> {
-    #[inline]
-    pub fn shrink(self) -> Unevaluated<'tcx, ()> {
-        debug_assert_eq!(self.promoted, None);
-        Unevaluated { def: self.def, substs: self.substs, promoted: () }
-    }
-}
-
-impl<'tcx> Unevaluated<'tcx, ()> {
+impl<'tcx> UnevaluatedConst<'tcx> {
     #[inline]
-    pub fn expand(self) -> Unevaluated<'tcx> {
-        Unevaluated { def: self.def, substs: self.substs, promoted: None }
+    pub fn expand(self) -> mir::UnevaluatedConst<'tcx> {
+        mir::UnevaluatedConst { def: self.def, substs: self.substs, promoted: None }
     }
 }
 
-impl<'tcx, P: Default> Unevaluated<'tcx, P> {
+impl<'tcx> UnevaluatedConst<'tcx> {
     #[inline]
-    pub fn new(def: ty::WithOptConstParam<DefId>, substs: SubstsRef<'tcx>) -> Unevaluated<'tcx, P> {
-        Unevaluated { def, substs, promoted: Default::default() }
+    pub fn new(
+        def: ty::WithOptConstParam<DefId>,
+        substs: SubstsRef<'tcx>,
+    ) -> UnevaluatedConst<'tcx> {
+        UnevaluatedConst { def, substs }
     }
 }
 
@@ -67,7 +62,7 @@ pub enum ConstKind<'tcx> {
 
     /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
     /// variants when the code is monomorphic enough for that.
-    Unevaluated(Unevaluated<'tcx, ()>),
+    Unevaluated(UnevaluatedConst<'tcx>),
 
     /// Used to hold computed value.
     Value(ty::ValTree<'tcx>),
@@ -114,7 +109,6 @@ impl<'tcx> ConstKind<'tcx> {
 
 /// An inference variable for a const, for use in const generics.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
-#[derive(HashStable)]
 pub enum InferConst<'tcx> {
     /// Infer the value of the const.
     Var(ty::ConstVid<'tcx>),
@@ -122,6 +116,15 @@ pub enum InferConst<'tcx> {
     Fresh(u32),
 }
 
+impl<CTX> HashStable<CTX> for InferConst<'_> {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        match self {
+            InferConst::Var(_) => panic!("const variables should not be hashed: {self:?}"),
+            InferConst::Fresh(i) => i.hash_stable(hcx, hasher),
+        }
+    }
+}
+
 enum EvalMode {
     Typeck,
     Mir,
@@ -185,8 +188,6 @@ impl<'tcx> ConstKind<'tcx> {
         if let ConstKind::Unevaluated(unevaluated) = self {
             use crate::mir::interpret::ErrorHandled;
 
-            assert_eq!(unevaluated.promoted, ());
-
             // HACK(eddyb) this erases lifetimes even though `const_eval_resolve`
             // also does later, but we want to do it before checking for
             // inference variables.
@@ -204,10 +205,9 @@ impl<'tcx> ConstKind<'tcx> {
             // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that
             // we can call `infcx.const_eval_resolve` which handles inference variables.
             let param_env_and = if param_env_and.needs_infer() {
-                tcx.param_env(unevaluated.def.did).and(ty::Unevaluated {
+                tcx.param_env(unevaluated.def.did).and(ty::UnevaluatedConst {
                     def: unevaluated.def,
                     substs: InternalSubsts::identity_for_item(tcx, unevaluated.def.did),
-                    promoted: (),
                 })
             } else {
                 param_env_and
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 0b497fa4a..3d7e2a083 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1,10 +1,10 @@
 //! Type context book-keeping.
 
 use crate::arena::Arena;
-use crate::dep_graph::{DepGraph, DepKind, DepKindStruct};
+use crate::dep_graph::{DepGraph, DepKindStruct};
 use crate::hir::place::Place as HirPlace;
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
-use crate::lint::{struct_lint_level, LintLevelSource};
+use crate::lint::struct_lint_level;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::resolve_lifetime;
 use crate::middle::stability;
@@ -15,7 +15,6 @@ use crate::mir::{
 use crate::thir::Thir;
 use crate::traits;
 use crate::ty::query::{self, TyCtxtAt};
-use crate::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSubsts};
 use crate::ty::{
     self, AdtDef, AdtDefData, AdtKind, Binder, BindingMode, BoundVar, CanonicalPolyFnSig,
     ClosureSizeProfileData, Const, ConstS, ConstVid, DefIdTree, ExistentialPredicate, FloatTy,
@@ -24,6 +23,7 @@ use crate::ty::{
     RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind, TyS, TyVar, TyVid, TypeAndMut, UintTy,
     Visibility,
 };
+use crate::ty::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef, UserSubsts};
 use rustc_ast as ast;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -34,12 +34,16 @@ use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::sync::{self, Lock, Lrc, ReadGuard, RwLock, WorkerLocal};
+use rustc_data_structures::unord::UnordSet;
 use rustc_data_structures::vec_map::VecMap;
-use rustc_errors::{DecorateLint, ErrorGuaranteed, LintDiagnosticBuilder, MultiSpan};
+use rustc_errors::{
+    DecorateLint, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, MultiSpan,
+};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
+use rustc_hir::hir_id::OwnerId;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{
@@ -53,7 +57,7 @@ use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{CrateType, OutputFilenames};
 use rustc_session::cstore::CrateStoreDyn;
-use rustc_session::lint::{Level, Lint};
+use rustc_session::lint::Lint;
 use rustc_session::Limit;
 use rustc_session::Session;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
@@ -76,7 +80,7 @@ use std::mem;
 use std::ops::{Bound, Deref};
 use std::sync::Arc;
 
-use super::{ImplPolarity, RvalueScopes};
+use super::{ImplPolarity, ResolverOutputs, RvalueScopes};
 
 pub trait OnDiskCache<'tcx>: rustc_data_structures::sync::Sync {
     /// Creates a new `OnDiskCache` instance from the serialized data in `data`.
@@ -195,9 +199,9 @@ impl<'tcx> CtxtInterners<'tcx> {
                 .intern(kind, |kind| {
                     let flags = super::flags::FlagComputation::for_kind(&kind);
 
-                    // It's impossible to hash inference regions (and will ICE), so we don't need to try to cache them.
+                    // It's impossible to hash inference variables (and will ICE), so we don't need to try to cache them.
                     // Without incremental, we rarely stable-hash types, so let's not do it proactively.
-                    let stable_hash = if flags.flags.intersects(TypeFlags::HAS_RE_INFER)
+                    let stable_hash = if flags.flags.intersects(TypeFlags::NEEDS_INFER)
                         || sess.opts.incremental.is_none()
                     {
                         Fingerprint::ZERO
@@ -288,7 +292,7 @@ pub struct CommonConsts<'tcx> {
 }
 
 pub struct LocalTableInContext<'a, V> {
-    hir_owner: LocalDefId,
+    hir_owner: OwnerId,
     data: &'a ItemLocalMap<V>,
 }
 
@@ -300,7 +304,7 @@ pub struct LocalTableInContext<'a, V> {
 /// would result in lookup errors, or worse, in silently wrong data being
 /// stored/returned.
 #[inline]
-fn validate_hir_id_for_typeck_results(hir_owner: LocalDefId, hir_id: hir::HirId) {
+fn validate_hir_id_for_typeck_results(hir_owner: OwnerId, hir_id: hir::HirId) {
     if hir_id.owner != hir_owner {
         invalid_hir_id_for_typeck_results(hir_owner, hir_id);
     }
@@ -308,7 +312,7 @@ fn validate_hir_id_for_typeck_results(hir_owner: LocalDefId, hir_id: hir::HirId)
 
 #[cold]
 #[inline(never)]
-fn invalid_hir_id_for_typeck_results(hir_owner: LocalDefId, hir_id: hir::HirId) {
+fn invalid_hir_id_for_typeck_results(hir_owner: OwnerId, hir_id: hir::HirId) {
     ty::tls::with(|tcx| {
         bug!(
             "node {} with HirId::owner {:?} cannot be placed in TypeckResults with hir_owner {:?}",
@@ -344,7 +348,7 @@ impl<'a, V> ::std::ops::Index<hir::HirId> for LocalTableInContext<'a, V> {
 }
 
 pub struct LocalTableInContextMut<'a, V> {
-    hir_owner: LocalDefId,
+    hir_owner: OwnerId,
     data: &'a mut ItemLocalMap<V>,
 }
 
@@ -416,7 +420,7 @@ pub struct GeneratorDiagnosticData<'tcx> {
 #[derive(TyEncodable, TyDecodable, Debug, HashStable)]
 pub struct TypeckResults<'tcx> {
     /// The `HirId::owner` all `ItemLocalId`s in this table are relative to.
-    pub hir_owner: LocalDefId,
+    pub hir_owner: OwnerId,
 
     /// Resolved definitions for `<T>::X` associated paths and
     /// method calls, including those of overloaded operators.
@@ -528,19 +532,17 @@ pub struct TypeckResults<'tcx> {
     /// This is used for warning unused imports. During type
     /// checking, this `Lrc` should not be cloned: it must have a ref-count
     /// of 1 so that we can insert things into the set mutably.
-    pub used_trait_imports: Lrc<FxHashSet<LocalDefId>>,
+    pub used_trait_imports: Lrc<UnordSet<LocalDefId>>,
 
     /// If any errors occurred while type-checking this body,
     /// this field will be set to `Some(ErrorGuaranteed)`.
     pub tainted_by_errors: Option<ErrorGuaranteed>,
 
     /// All the opaque types that have hidden types set
-    /// by this function. For return-position-impl-trait we also store the
-    /// type here, so that mir-borrowck can figure out hidden types,
+    /// by this function. We also store the
+    /// type here, so that mir-borrowck can use it as a hint for figuring out hidden types,
     /// even if they are only set in dead code (which doesn't show up in MIR).
-    /// For type-alias-impl-trait, this map is only used to prevent query cycles,
-    /// so the hidden types are all `None`.
-    pub concrete_opaque_types: VecMap<LocalDefId, Option<Ty<'tcx>>>,
+    pub concrete_opaque_types: VecMap<LocalDefId, ty::OpaqueHiddenType<'tcx>>,
 
     /// Tracks the minimum captures required for a closure;
     /// see `MinCaptureInformationMap` for more details.
@@ -572,7 +574,7 @@ pub struct TypeckResults<'tcx> {
 
     /// Tracks the rvalue scoping rules which defines finer scoping for rvalue expressions
     /// by applying extended parameter rules.
-    /// Details may be find in `rustc_typeck::check::rvalue_scopes`.
+    /// Details may be find in `rustc_hir_analysis::check::rvalue_scopes`.
     pub rvalue_scopes: RvalueScopes,
 
     /// Stores the type, expression, span and optional scope span of all types
@@ -591,7 +593,7 @@ pub struct TypeckResults<'tcx> {
 }
 
 impl<'tcx> TypeckResults<'tcx> {
-    pub fn new(hir_owner: LocalDefId) -> TypeckResults<'tcx> {
+    pub fn new(hir_owner: OwnerId) -> TypeckResults<'tcx> {
         TypeckResults {
             hir_owner,
             type_dependent_defs: Default::default(),
@@ -1066,10 +1068,9 @@ pub struct GlobalCtxt<'tcx> {
     pub consts: CommonConsts<'tcx>,
 
     definitions: RwLock<Definitions>,
-    cstore: Box<CrateStoreDyn>,
 
     /// Output of the resolver.
-    pub(crate) untracked_resolutions: ty::ResolverOutputs,
+    pub(crate) untracked_resolutions: ty::ResolverGlobalCtxt,
     untracked_resolver_for_lowering: Steal<ty::ResolverAstLowering>,
     /// The entire crate as AST. This field serves as the input for the hir_crate query,
     /// which lowers it from AST to HIR. It must not be read or used by anything else.
@@ -1083,7 +1084,7 @@ pub struct GlobalCtxt<'tcx> {
 
     pub queries: &'tcx dyn query::QueryEngine<'tcx>,
     pub query_caches: query::QueryCaches<'tcx>,
-    query_kinds: &'tcx [DepKindStruct<'tcx>],
+    pub(crate) query_kinds: &'tcx [DepKindStruct<'tcx>],
 
     // Internal caches for metadata decoding. No need to track deps on this.
     pub ty_rcache: Lock<FxHashMap<ty::CReaderCacheKey, Ty<'tcx>>>,
@@ -1232,10 +1233,7 @@ impl<'tcx> TyCtxt<'tcx> {
         lint_store: Lrc<dyn Any + sync::Send + sync::Sync>,
         arena: &'tcx WorkerLocal<Arena<'tcx>>,
         hir_arena: &'tcx WorkerLocal<hir::Arena<'tcx>>,
-        definitions: Definitions,
-        cstore: Box<CrateStoreDyn>,
-        untracked_resolutions: ty::ResolverOutputs,
-        untracked_resolver_for_lowering: ty::ResolverAstLowering,
+        resolver_outputs: ResolverOutputs,
         krate: Lrc<ast::Crate>,
         dep_graph: DepGraph,
         on_disk_cache: Option<&'tcx dyn OnDiskCache<'tcx>>,
@@ -1244,6 +1242,11 @@ impl<'tcx> TyCtxt<'tcx> {
         crate_name: &str,
         output_filenames: OutputFilenames,
     ) -> GlobalCtxt<'tcx> {
+        let ResolverOutputs {
+            definitions,
+            global_ctxt: untracked_resolutions,
+            ast_lowering: untracked_resolver_for_lowering,
+        } = resolver_outputs;
         let data_layout = TargetDataLayout::parse(&s.target).unwrap_or_else(|err| {
             s.emit_fatal(err);
         });
@@ -1252,7 +1255,7 @@ impl<'tcx> TyCtxt<'tcx> {
             &interners,
             s,
             &definitions,
-            &*cstore,
+            &*untracked_resolutions.cstore,
             // This is only used to create a stable hashing context.
             &untracked_resolutions.source_span,
         );
@@ -1267,7 +1270,6 @@ impl<'tcx> TyCtxt<'tcx> {
             interners,
             dep_graph,
             definitions: RwLock::new(definitions),
-            cstore,
             prof: s.prof.clone(),
             types: common_types,
             lifetimes: common_lifetimes,
@@ -1290,10 +1292,6 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    pub(crate) fn query_kind(self, k: DepKind) -> &'tcx DepKindStruct<'tcx> {
-        &self.query_kinds[k as usize]
-    }
-
     /// Constructs a `TyKind::Error` type and registers a `delay_span_bug` to ensure it gets used.
     #[track_caller]
     pub fn ty_error(self) -> Ty<'tcx> {
@@ -1372,7 +1370,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if let Some(id) = id.as_local() {
             self.definitions_untracked().def_key(id)
         } else {
-            self.cstore.def_key(id)
+            self.untracked_resolutions.cstore.def_key(id)
         }
     }
 
@@ -1386,7 +1384,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if let Some(id) = id.as_local() {
             self.definitions_untracked().def_path(id)
         } else {
-            self.cstore.def_path(id)
+            self.untracked_resolutions.cstore.def_path(id)
         }
     }
 
@@ -1396,7 +1394,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if let Some(def_id) = def_id.as_local() {
             self.definitions_untracked().def_path_hash(def_id)
         } else {
-            self.cstore.def_path_hash(def_id)
+            self.untracked_resolutions.cstore.def_path_hash(def_id)
         }
     }
 
@@ -1405,7 +1403,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if crate_num == LOCAL_CRATE {
             self.sess.local_stable_crate_id()
         } else {
-            self.cstore.stable_crate_id(crate_num)
+            self.untracked_resolutions.cstore.stable_crate_id(crate_num)
         }
     }
 
@@ -1416,7 +1414,7 @@ impl<'tcx> TyCtxt<'tcx> {
         if stable_crate_id == self.sess.local_stable_crate_id() {
             LOCAL_CRATE
         } else {
-            self.cstore.stable_crate_id_to_crate_num(stable_crate_id)
+            self.untracked_resolutions.cstore.stable_crate_id_to_crate_num(stable_crate_id)
         }
     }
 
@@ -1435,8 +1433,9 @@ impl<'tcx> TyCtxt<'tcx> {
         } else {
             // If this is a DefPathHash from an upstream crate, let the CrateStore map
             // it to a DefId.
-            let cnum = self.cstore.stable_crate_id_to_crate_num(stable_crate_id);
-            self.cstore.def_path_hash_to_def_id(cnum, hash)
+            let cstore = &*self.untracked_resolutions.cstore;
+            let cnum = cstore.stable_crate_id_to_crate_num(stable_crate_id);
+            cstore.def_path_hash_to_def_id(cnum, hash)
         }
     }
 
@@ -1448,7 +1447,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let (crate_name, stable_crate_id) = if def_id.is_local() {
             (self.crate_name, self.sess.local_stable_crate_id())
         } else {
-            let cstore = &self.cstore;
+            let cstore = &*self.untracked_resolutions.cstore;
             (cstore.crate_name(def_id.krate), cstore.stable_crate_id(def_id.krate))
         };
 
@@ -1523,7 +1522,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Note that this is *untracked* and should only be used within the query
     /// system if the result is otherwise tracked through queries
     pub fn cstore_untracked(self) -> &'tcx CrateStoreDyn {
-        &*self.cstore
+        &*self.untracked_resolutions.cstore
     }
 
     /// Note that this is *untracked* and should only be used within the query
@@ -1549,7 +1548,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let hcx = StableHashingContext::new(
             self.sess,
             &*definitions,
-            &*self.cstore,
+            &*self.untracked_resolutions.cstore,
             &self.untracked_resolutions.source_span,
         );
         f(hcx)
@@ -1725,7 +1724,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
     #[inline]
     pub fn local_visibility(self, def_id: LocalDefId) -> Visibility {
-        self.visibility(def_id.to_def_id()).expect_local()
+        self.visibility(def_id).expect_local()
     }
 }
 
@@ -2367,7 +2366,7 @@ impl<'tcx> TyCtxt<'tcx> {
             st,
             self.sess,
             &self.definitions.read(),
-            &*self.cstore,
+            &*self.untracked_resolutions.cstore,
             // This is only used to create a stable hashing context.
             &self.untracked_resolutions.source_span,
         )
@@ -2812,44 +2811,6 @@ impl<'tcx> TyCtxt<'tcx> {
         iter.intern_with(|xs| self.intern_bound_variable_kinds(xs))
     }
 
-    /// Walks upwards from `id` to find a node which might change lint levels with attributes.
-    /// It stops at `bound` and just returns it if reached.
-    pub fn maybe_lint_level_root_bounded(self, mut id: HirId, bound: HirId) -> HirId {
-        let hir = self.hir();
-        loop {
-            if id == bound {
-                return bound;
-            }
-
-            if hir.attrs(id).iter().any(|attr| Level::from_attr(attr).is_some()) {
-                return id;
-            }
-            let next = hir.get_parent_node(id);
-            if next == id {
-                bug!("lint traversal reached the root of the crate");
-            }
-            id = next;
-        }
-    }
-
-    pub fn lint_level_at_node(
-        self,
-        lint: &'static Lint,
-        mut id: hir::HirId,
-    ) -> (Level, LintLevelSource) {
-        let sets = self.lint_levels(());
-        loop {
-            if let Some(pair) = sets.level_and_source(lint, id, self.sess) {
-                return pair;
-            }
-            let next = self.hir().get_parent_node(id);
-            if next == id {
-                bug!("lint traversal reached the root of the crate");
-            }
-            id = next;
-        }
-    }
-
     /// Emit a lint at `span` from a lint struct (some type that implements `DecorateLint`,
     /// typically generated by `#[derive(LintDiagnostic)]`).
     pub fn emit_spanned_lint(
@@ -2859,18 +2820,28 @@ impl<'tcx> TyCtxt<'tcx> {
         span: impl Into<MultiSpan>,
         decorator: impl for<'a> DecorateLint<'a, ()>,
     ) {
-        self.struct_span_lint_hir(lint, hir_id, span, |diag| decorator.decorate_lint(diag))
+        self.struct_span_lint_hir(lint, hir_id, span, decorator.msg(), |diag| {
+            decorator.decorate_lint(diag)
+        })
     }
 
+    /// Emit a lint at the appropriate level for a hir node, with an associated span.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     pub fn struct_span_lint_hir(
         self,
         lint: &'static Lint,
         hir_id: HirId,
         span: impl Into<MultiSpan>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
+        msg: impl Into<DiagnosticMessage>,
+        decorate: impl for<'a, 'b> FnOnce(
+            &'b mut DiagnosticBuilder<'a, ()>,
+        ) -> &'b mut DiagnosticBuilder<'a, ()>,
     ) {
         let (level, src) = self.lint_level_at_node(lint, hir_id);
-        struct_lint_level(self.sess, lint, level, src, Some(span.into()), decorate);
+        struct_lint_level(self.sess, lint, level, src, Some(span.into()), msg, decorate);
     }
 
     /// Emit a lint from a lint struct (some type that implements `DecorateLint`, typically
@@ -2881,17 +2852,25 @@ impl<'tcx> TyCtxt<'tcx> {
         id: HirId,
         decorator: impl for<'a> DecorateLint<'a, ()>,
     ) {
-        self.struct_lint_node(lint, id, |diag| decorator.decorate_lint(diag))
+        self.struct_lint_node(lint, id, decorator.msg(), |diag| decorator.decorate_lint(diag))
     }
 
+    /// Emit a lint at the appropriate level for a hir node.
+    ///
+    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
+    ///
+    /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     pub fn struct_lint_node(
         self,
         lint: &'static Lint,
         id: HirId,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
+        msg: impl Into<DiagnosticMessage>,
+        decorate: impl for<'a, 'b> FnOnce(
+            &'b mut DiagnosticBuilder<'a, ()>,
+        ) -> &'b mut DiagnosticBuilder<'a, ()>,
     ) {
         let (level, src) = self.lint_level_at_node(lint, id);
-        struct_lint_level(self.sess, lint, level, src, None, decorate);
+        struct_lint_level(self.sess, lint, level, src, None, msg, decorate);
     }
 
     pub fn in_scope_traits(self, id: HirId) -> Option<&'tcx [TraitCandidate]> {
@@ -2906,7 +2885,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn is_late_bound(self, id: HirId) -> bool {
-        self.is_late_bound_map(id.owner).map_or(false, |set| {
+        self.is_late_bound_map(id.owner.def_id).map_or(false, |set| {
             let def_id = self.hir().local_def_id(id);
             set.contains(&def_id)
         })
@@ -2977,6 +2956,21 @@ impl<'tcx> TyCtxtAt<'tcx> {
     }
 }
 
+/// Parameter attributes that can only be determined by examining the body of a function instead
+/// of just its signature.
+///
+/// These can be useful for optimization purposes when a function is directly called. We compute
+/// them and store them into the crate metadata so that downstream crates can make use of them.
+///
+/// Right now, we only have `read_only`, but `no_capture` and `no_alias` might be useful in the
+/// future.
+#[derive(Clone, Copy, PartialEq, Debug, Default, TyDecodable, TyEncodable, HashStable)]
+pub struct DeducedParamAttrs {
+    /// The parameter is marked immutable in the function and contains no `UnsafeCell` (i.e. its
+    /// type is freeze).
+    pub read_only: bool,
+}
+
 // We are comparing types with different invariant lifetimes, so `ptr::eq`
 // won't work for us.
 fn ptr_eq<T, U>(t: *const T, u: *const U) -> bool {
diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index 855917fb8..b8fd01e6a 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -511,3 +511,11 @@ impl<'tcx> TypeVisitor<'tcx> for IsSuggestableVisitor<'tcx> {
         c.super_visit_with(self)
     }
 }
+
+#[derive(Diagnostic)]
+#[diag(borrowck_const_not_used_in_type_alias)]
+pub(super) struct ConstNotUsedTraitAlias {
+    pub ct: String,
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_middle/src/ty/erase_regions.rs b/compiler/rustc_middle/src/ty/erase_regions.rs
index 3226950e7..ffdac93bc 100644
--- a/compiler/rustc_middle/src/ty/erase_regions.rs
+++ b/compiler/rustc_middle/src/ty/erase_regions.rs
@@ -1,4 +1,3 @@
-use crate::mir;
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use crate::ty::visit::TypeVisitable;
 use crate::ty::{self, Ty, TyCtxt, TypeFlags};
@@ -67,8 +66,4 @@ impl<'tcx> TypeFolder<'tcx> for RegionEraserVisitor<'tcx> {
             _ => self.tcx.lifetimes.re_erased,
         }
     }
-
-    fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
-        c.super_fold_with(self)
-    }
 }
diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index 01e1e97b2..4e6cdb786 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -861,7 +861,7 @@ fn foo(&self) -> Self::T { String::new() }
         // When `body_owner` is an `impl` or `trait` item, look in its associated types for
         // `expected` and point at it.
         let parent_id = self.hir().get_parent_item(hir_id);
-        let item = self.hir().find_by_def_id(parent_id);
+        let item = self.hir().find_by_def_id(parent_id.def_id);
         debug!("expected_projection parent item {:?}", item);
         match item {
             Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., items), .. })) => {
@@ -872,9 +872,9 @@ fn foo(&self) -> Self::T { String::new() }
                             // FIXME: account for returning some type in a trait fn impl that has
                             // an assoc type as a return type (#72076).
                             if let hir::Defaultness::Default { has_value: true } =
-                                self.impl_defaultness(item.id.def_id)
+                                self.impl_defaultness(item.id.owner_id)
                             {
-                                if self.type_of(item.id.def_id) == found {
+                                if self.type_of(item.id.owner_id) == found {
                                     diag.span_label(
                                         item.span,
                                         "associated type defaults can't be assumed inside the \
@@ -894,7 +894,7 @@ fn foo(&self) -> Self::T { String::new() }
             })) => {
                 for item in &items[..] {
                     if let hir::AssocItemKind::Type = item.kind {
-                        if self.type_of(item.id.def_id) == found {
+                        if self.type_of(item.id.owner_id) == found {
                             diag.span_label(item.span, "expected this associated type");
                             return true;
                         }
diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs
index 8d019a3ba..3be0bc4de 100644
--- a/compiler/rustc_middle/src/ty/fast_reject.rs
+++ b/compiler/rustc_middle/src/ty/fast_reject.rs
@@ -132,7 +132,7 @@ pub fn simplify_type<'tcx>(
             // don't unify with anything else as long as they are fully normalized.
             //
             // We will have to be careful with lazy normalization here.
-            TreatParams::AsPlaceholder if !ty.has_infer_types_or_consts() => {
+            TreatParams::AsPlaceholder if !ty.has_non_region_infer() => {
                 debug!("treating `{}` as a placeholder", ty);
                 Some(PlaceholderSimplifiedType)
             }
@@ -384,14 +384,7 @@ impl DeepRejectCtxt {
             // they might unify with any value.
             ty::ConstKind::Unevaluated(_) | ty::ConstKind::Error(_) => true,
             ty::ConstKind::Value(obl) => match k {
-                ty::ConstKind::Value(imp) => {
-                    // FIXME(valtrees): Once we have valtrees, we can just
-                    // compare them directly here.
-                    match (obl.try_to_scalar_int(), imp.try_to_scalar_int()) {
-                        (Some(obl), Some(imp)) => obl == imp,
-                        _ => true,
-                    }
-                }
+                ty::ConstKind::Value(imp) => obl == imp,
                 _ => true,
             },
 
diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs
index 98b8a7386..7201737be 100644
--- a/compiler/rustc_middle/src/ty/flags.rs
+++ b/compiler/rustc_middle/src/ty/flags.rs
@@ -34,12 +34,6 @@ impl FlagComputation {
         result.flags
     }
 
-    pub fn for_unevaluated_const(uv: ty::Unevaluated<'_>) -> TypeFlags {
-        let mut result = FlagComputation::new();
-        result.add_unevaluated_const(uv);
-        result.flags
-    }
-
     fn add_flags(&mut self, flags: TypeFlags) {
         self.flags = self.flags | flags;
     }
@@ -256,7 +250,7 @@ impl FlagComputation {
                 self.add_substs(substs);
             }
             ty::PredicateKind::ConstEvaluatable(uv) => {
-                self.add_unevaluated_const(uv);
+                self.add_const(uv);
             }
             ty::PredicateKind::ConstEquate(expected, found) => {
                 self.add_const(expected);
@@ -289,7 +283,10 @@ impl FlagComputation {
     fn add_const(&mut self, c: ty::Const<'_>) {
         self.add_ty(c.ty());
         match c.kind() {
-            ty::ConstKind::Unevaluated(unevaluated) => self.add_unevaluated_const(unevaluated),
+            ty::ConstKind::Unevaluated(uv) => {
+                self.add_substs(uv.substs);
+                self.add_flags(TypeFlags::HAS_CT_PROJECTION);
+            }
             ty::ConstKind::Infer(infer) => {
                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
                 match infer {
@@ -313,11 +310,6 @@ impl FlagComputation {
         }
     }
 
-    fn add_unevaluated_const<P>(&mut self, ct: ty::Unevaluated<'_, P>) {
-        self.add_substs(ct.substs);
-        self.add_flags(TypeFlags::HAS_CT_PROJECTION);
-    }
-
     fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
         self.add_substs(projection.substs);
         match projection.term.unpack() {
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index cac95e14a..54f1499eb 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -13,8 +13,7 @@
 //!
 //! There are three groups of traits involved in each traversal.
 //! - `TypeFoldable`. This is implemented once for many types, including:
-//!   - Types of interest, for which the the methods delegate to the
-//!     folder.
+//!   - Types of interest, for which the methods delegate to the folder.
 //!   - All other types, including generic containers like `Vec` and `Option`.
 //!     It defines a "skeleton" of how they should be folded.
 //! - `TypeSuperFoldable`. This is implemented only for each type of interest,
@@ -43,7 +42,6 @@
 //!     - ty.super_fold_with(folder)
 //! - u.fold_with(folder)
 //! ```
-use crate::mir;
 use crate::ty::{self, Binder, BoundTy, Ty, TyCtxt, TypeVisitable};
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_hir::def_id::DefId;
@@ -128,17 +126,9 @@ pub trait TypeFolder<'tcx>: FallibleTypeFolder<'tcx, Error = !> {
         c.super_fold_with(self)
     }
 
-    fn fold_unevaluated(&mut self, uv: ty::Unevaluated<'tcx>) -> ty::Unevaluated<'tcx> {
-        uv.super_fold_with(self)
-    }
-
     fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
         p.super_fold_with(self)
     }
-
-    fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
-        bug!("most type folders should not be folding MIR datastructures: {:?}", c)
-    }
 }
 
 /// This trait is implemented for every folding traversal. There is a fold
@@ -172,26 +162,12 @@ pub trait FallibleTypeFolder<'tcx>: Sized {
         c.try_super_fold_with(self)
     }
 
-    fn try_fold_unevaluated(
-        &mut self,
-        c: ty::Unevaluated<'tcx>,
-    ) -> Result<ty::Unevaluated<'tcx>, Self::Error> {
-        c.try_super_fold_with(self)
-    }
-
     fn try_fold_predicate(
         &mut self,
         p: ty::Predicate<'tcx>,
     ) -> Result<ty::Predicate<'tcx>, Self::Error> {
         p.try_super_fold_with(self)
     }
-
-    fn try_fold_mir_const(
-        &mut self,
-        c: mir::ConstantKind<'tcx>,
-    ) -> Result<mir::ConstantKind<'tcx>, Self::Error> {
-        bug!("most type folders should not be folding MIR datastructures: {:?}", c)
-    }
 }
 
 // This blanket implementation of the fallible trait for infallible folders
@@ -225,23 +201,9 @@ where
         Ok(self.fold_const(c))
     }
 
-    fn try_fold_unevaluated(
-        &mut self,
-        c: ty::Unevaluated<'tcx>,
-    ) -> Result<ty::Unevaluated<'tcx>, !> {
-        Ok(self.fold_unevaluated(c))
-    }
-
     fn try_fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> Result<ty::Predicate<'tcx>, !> {
         Ok(self.fold_predicate(p))
     }
-
-    fn try_fold_mir_const(
-        &mut self,
-        c: mir::ConstantKind<'tcx>,
-    ) -> Result<mir::ConstantKind<'tcx>, !> {
-        Ok(self.fold_mir_const(c))
-    }
 }
 
 ///////////////////////////////////////////////////////////////////////////
diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index 0c8bdde9c..19754d145 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -1,6 +1,5 @@
 use crate::ty;
-use crate::ty::subst::{Subst, SubstsRef};
-use crate::ty::EarlyBinder;
+use crate::ty::{EarlyBinder, SubstsRef};
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::DefId;
diff --git a/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs b/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs
deleted file mode 100644
index c4ad698ba..000000000
--- a/compiler/rustc_middle/src/ty/inhabitedness/def_id_forest.rs
+++ /dev/null
@@ -1,145 +0,0 @@
-use crate::ty::context::TyCtxt;
-use crate::ty::{DefId, DefIdTree};
-use rustc_span::def_id::CRATE_DEF_ID;
-use smallvec::SmallVec;
-use std::mem;
-
-use DefIdForest::*;
-
-/// Represents a forest of `DefId`s closed under the ancestor relation. That is,
-/// if a `DefId` representing a module is contained in the forest then all
-/// `DefId`s defined in that module or submodules are also implicitly contained
-/// in the forest.
-///
-/// This is used to represent a set of modules in which a type is visibly
-/// uninhabited.
-///
-/// We store the minimal set of `DefId`s required to represent the whole set. If A and B are
-/// `DefId`s in the `DefIdForest`, and A is a parent of B, then only A will be stored. When this is
-/// used with `type_uninhabited_from`, there will very rarely be more than one `DefId` stored.
-#[derive(Copy, Clone, HashStable, Debug)]
-pub enum DefIdForest<'a> {
-    Empty,
-    Single(DefId),
-    /// This variant is very rare.
-    /// Invariant: >1 elements
-    Multiple(&'a [DefId]),
-}
-
-/// Tests whether a slice of roots contains a given DefId.
-#[inline]
-fn slice_contains<'tcx>(tcx: TyCtxt<'tcx>, slice: &[DefId], id: DefId) -> bool {
-    slice.iter().any(|root_id| tcx.is_descendant_of(id, *root_id))
-}
-
-impl<'tcx> DefIdForest<'tcx> {
-    /// Creates an empty forest.
-    pub fn empty() -> DefIdForest<'tcx> {
-        DefIdForest::Empty
-    }
-
-    /// Creates a forest consisting of a single tree representing the entire
-    /// crate.
-    #[inline]
-    pub fn full() -> DefIdForest<'tcx> {
-        DefIdForest::from_id(CRATE_DEF_ID.to_def_id())
-    }
-
-    /// Creates a forest containing a `DefId` and all its descendants.
-    pub fn from_id(id: DefId) -> DefIdForest<'tcx> {
-        DefIdForest::Single(id)
-    }
-
-    fn as_slice(&self) -> &[DefId] {
-        match self {
-            Empty => &[],
-            Single(id) => std::slice::from_ref(id),
-            Multiple(root_ids) => root_ids,
-        }
-    }
-
-    // Only allocates in the rare `Multiple` case.
-    fn from_vec(tcx: TyCtxt<'tcx>, root_ids: SmallVec<[DefId; 1]>) -> DefIdForest<'tcx> {
-        match &root_ids[..] {
-            [] => Empty,
-            [id] => Single(*id),
-            _ => DefIdForest::Multiple(tcx.arena.alloc_from_iter(root_ids)),
-        }
-    }
-
-    /// Tests whether the forest is empty.
-    pub fn is_empty(&self) -> bool {
-        match self {
-            Empty => true,
-            Single(..) | Multiple(..) => false,
-        }
-    }
-
-    /// Iterate over the set of roots.
-    fn iter(&self) -> impl Iterator<Item = DefId> + '_ {
-        self.as_slice().iter().copied()
-    }
-
-    /// Tests whether the forest contains a given DefId.
-    pub fn contains(&self, tcx: TyCtxt<'tcx>, id: DefId) -> bool {
-        slice_contains(tcx, self.as_slice(), id)
-    }
-
-    /// Calculate the intersection of a collection of forests.
-    pub fn intersection<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest<'tcx>
-    where
-        I: IntoIterator<Item = DefIdForest<'tcx>>,
-    {
-        let mut iter = iter.into_iter();
-        let mut ret: SmallVec<[_; 1]> = if let Some(first) = iter.next() {
-            SmallVec::from_slice(first.as_slice())
-        } else {
-            return DefIdForest::full();
-        };
-
-        let mut next_ret: SmallVec<[_; 1]> = SmallVec::new();
-        for next_forest in iter {
-            // No need to continue if the intersection is already empty.
-            if ret.is_empty() || next_forest.is_empty() {
-                return DefIdForest::empty();
-            }
-
-            // We keep the elements in `ret` that are also in `next_forest`.
-            next_ret.extend(ret.iter().copied().filter(|&id| next_forest.contains(tcx, id)));
-            // We keep the elements in `next_forest` that are also in `ret`.
-            next_ret.extend(next_forest.iter().filter(|&id| slice_contains(tcx, &ret, id)));
-
-            mem::swap(&mut next_ret, &mut ret);
-            next_ret.clear();
-        }
-        DefIdForest::from_vec(tcx, ret)
-    }
-
-    /// Calculate the union of a collection of forests.
-    pub fn union<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest<'tcx>
-    where
-        I: IntoIterator<Item = DefIdForest<'tcx>>,
-    {
-        let mut ret: SmallVec<[_; 1]> = SmallVec::new();
-        let mut next_ret: SmallVec<[_; 1]> = SmallVec::new();
-        for next_forest in iter {
-            // Union with the empty set is a no-op.
-            if next_forest.is_empty() {
-                continue;
-            }
-
-            // We add everything in `ret` that is not in `next_forest`.
-            next_ret.extend(ret.iter().copied().filter(|&id| !next_forest.contains(tcx, id)));
-            // We add everything in `next_forest` that we haven't added yet.
-            for id in next_forest.iter() {
-                if !slice_contains(tcx, &next_ret, id) {
-                    next_ret.push(id);
-                }
-            }
-
-            mem::swap(&mut next_ret, &mut ret);
-            next_ret.clear();
-        }
-        DefIdForest::from_vec(tcx, ret)
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
new file mode 100644
index 000000000..b7aa45572
--- /dev/null
+++ b/compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs
@@ -0,0 +1,204 @@
+use crate::ty::context::TyCtxt;
+use crate::ty::{self, DefId, DefIdTree, ParamEnv, Ty};
+
+/// Represents whether some type is inhabited in a given context.
+/// Examples of uninhabited types are `!`, `enum Void {}`, or a struct
+/// containing either of those types.
+/// A type's inhabitedness may depend on the `ParamEnv` as well as what types
+/// are visible in the current module.
+#[derive(Clone, Copy, Debug, PartialEq, HashStable)]
+pub enum InhabitedPredicate<'tcx> {
+    /// Inhabited
+    True,
+    /// Uninhabited
+    False,
+    /// Uninhabited when a const value is non-zero. This occurs when there is an
+    /// array of uninhabited items, but the array is inhabited if it is empty.
+    ConstIsZero(ty::Const<'tcx>),
+    /// Uninhabited if within a certain module. This occurs when an uninhabited
+    /// type has restricted visibility.
+    NotInModule(DefId),
+    /// Inhabited if some generic type is inhabited.
+    /// These are replaced by calling [`Self::subst`].
+    GenericType(Ty<'tcx>),
+    /// A AND B
+    And(&'tcx [InhabitedPredicate<'tcx>; 2]),
+    /// A OR B
+    Or(&'tcx [InhabitedPredicate<'tcx>; 2]),
+}
+
+impl<'tcx> InhabitedPredicate<'tcx> {
+    /// Returns true if the corresponding type is inhabited in the given
+    /// `ParamEnv` and module
+    pub fn apply(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, module_def_id: DefId) -> bool {
+        let Ok(result) = self
+            .apply_inner::<!>(tcx, param_env, &|id| Ok(tcx.is_descendant_of(module_def_id, id)));
+        result
+    }
+
+    /// Same as `apply`, but returns `None` if self contains a module predicate
+    pub fn apply_any_module(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
+        self.apply_inner(tcx, param_env, &|_| Err(())).ok()
+    }
+
+    fn apply_inner<E>(
+        self,
+        tcx: TyCtxt<'tcx>,
+        param_env: ParamEnv<'tcx>,
+        in_module: &impl Fn(DefId) -> Result<bool, E>,
+    ) -> Result<bool, E> {
+        match self {
+            Self::False => Ok(false),
+            Self::True => Ok(true),
+            Self::ConstIsZero(const_) => match const_.try_eval_usize(tcx, param_env) {
+                None | Some(0) => Ok(true),
+                Some(1..) => Ok(false),
+            },
+            Self::NotInModule(id) => in_module(id).map(|in_mod| !in_mod),
+            Self::GenericType(_) => Ok(true),
+            Self::And([a, b]) => try_and(a, b, |x| x.apply_inner(tcx, param_env, in_module)),
+            Self::Or([a, b]) => try_or(a, b, |x| x.apply_inner(tcx, param_env, in_module)),
+        }
+    }
+
+    pub fn and(self, tcx: TyCtxt<'tcx>, other: Self) -> Self {
+        self.reduce_and(tcx, other).unwrap_or_else(|| Self::And(tcx.arena.alloc([self, other])))
+    }
+
+    pub fn or(self, tcx: TyCtxt<'tcx>, other: Self) -> Self {
+        self.reduce_or(tcx, other).unwrap_or_else(|| Self::Or(tcx.arena.alloc([self, other])))
+    }
+
+    pub fn all(tcx: TyCtxt<'tcx>, iter: impl IntoIterator<Item = Self>) -> Self {
+        let mut result = Self::True;
+        for pred in iter {
+            if matches!(pred, Self::False) {
+                return Self::False;
+            }
+            result = result.and(tcx, pred);
+        }
+        result
+    }
+
+    pub fn any(tcx: TyCtxt<'tcx>, iter: impl IntoIterator<Item = Self>) -> Self {
+        let mut result = Self::False;
+        for pred in iter {
+            if matches!(pred, Self::True) {
+                return Self::True;
+            }
+            result = result.or(tcx, pred);
+        }
+        result
+    }
+
+    fn reduce_and(self, tcx: TyCtxt<'tcx>, other: Self) -> Option<Self> {
+        match (self, other) {
+            (Self::True, a) | (a, Self::True) => Some(a),
+            (Self::False, _) | (_, Self::False) => Some(Self::False),
+            (Self::ConstIsZero(a), Self::ConstIsZero(b)) if a == b => Some(Self::ConstIsZero(a)),
+            (Self::NotInModule(a), Self::NotInModule(b)) if a == b => Some(Self::NotInModule(a)),
+            (Self::NotInModule(a), Self::NotInModule(b)) if tcx.is_descendant_of(a, b) => {
+                Some(Self::NotInModule(b))
+            }
+            (Self::NotInModule(a), Self::NotInModule(b)) if tcx.is_descendant_of(b, a) => {
+                Some(Self::NotInModule(a))
+            }
+            (Self::GenericType(a), Self::GenericType(b)) if a == b => Some(Self::GenericType(a)),
+            (Self::And(&[a, b]), c) | (c, Self::And(&[a, b])) => {
+                if let Some(ac) = a.reduce_and(tcx, c) {
+                    Some(ac.and(tcx, b))
+                } else if let Some(bc) = b.reduce_and(tcx, c) {
+                    Some(Self::And(tcx.arena.alloc([a, bc])))
+                } else {
+                    None
+                }
+            }
+            _ => None,
+        }
+    }
+
+    fn reduce_or(self, tcx: TyCtxt<'tcx>, other: Self) -> Option<Self> {
+        match (self, other) {
+            (Self::True, _) | (_, Self::True) => Some(Self::True),
+            (Self::False, a) | (a, Self::False) => Some(a),
+            (Self::ConstIsZero(a), Self::ConstIsZero(b)) if a == b => Some(Self::ConstIsZero(a)),
+            (Self::NotInModule(a), Self::NotInModule(b)) if a == b => Some(Self::NotInModule(a)),
+            (Self::NotInModule(a), Self::NotInModule(b)) if tcx.is_descendant_of(a, b) => {
+                Some(Self::NotInModule(a))
+            }
+            (Self::NotInModule(a), Self::NotInModule(b)) if tcx.is_descendant_of(b, a) => {
+                Some(Self::NotInModule(b))
+            }
+            (Self::GenericType(a), Self::GenericType(b)) if a == b => Some(Self::GenericType(a)),
+            (Self::Or(&[a, b]), c) | (c, Self::Or(&[a, b])) => {
+                if let Some(ac) = a.reduce_or(tcx, c) {
+                    Some(ac.or(tcx, b))
+                } else if let Some(bc) = b.reduce_or(tcx, c) {
+                    Some(Self::Or(tcx.arena.alloc([a, bc])))
+                } else {
+                    None
+                }
+            }
+            _ => None,
+        }
+    }
+
+    /// Replaces generic types with its corresponding predicate
+    pub fn subst(self, tcx: TyCtxt<'tcx>, substs: ty::SubstsRef<'tcx>) -> Self {
+        self.subst_opt(tcx, substs).unwrap_or(self)
+    }
+
+    fn subst_opt(self, tcx: TyCtxt<'tcx>, substs: ty::SubstsRef<'tcx>) -> Option<Self> {
+        match self {
+            Self::ConstIsZero(c) => {
+                let c = ty::EarlyBinder(c).subst(tcx, substs);
+                let pred = match c.kind().try_to_machine_usize(tcx) {
+                    Some(0) => Self::True,
+                    Some(1..) => Self::False,
+                    None => Self::ConstIsZero(c),
+                };
+                Some(pred)
+            }
+            Self::GenericType(t) => {
+                Some(ty::EarlyBinder(t).subst(tcx, substs).inhabited_predicate(tcx))
+            }
+            Self::And(&[a, b]) => match a.subst_opt(tcx, substs) {
+                None => b.subst_opt(tcx, substs).map(|b| a.and(tcx, b)),
+                Some(InhabitedPredicate::False) => Some(InhabitedPredicate::False),
+                Some(a) => Some(a.and(tcx, b.subst_opt(tcx, substs).unwrap_or(b))),
+            },
+            Self::Or(&[a, b]) => match a.subst_opt(tcx, substs) {
+                None => b.subst_opt(tcx, substs).map(|b| a.or(tcx, b)),
+                Some(InhabitedPredicate::True) => Some(InhabitedPredicate::True),
+                Some(a) => Some(a.or(tcx, b.subst_opt(tcx, substs).unwrap_or(b))),
+            },
+            _ => None,
+        }
+    }
+}
+
+// this is basically like `f(a)? && f(b)?` but different in the case of
+// `Ok(false) && Err(_) -> Ok(false)`
+fn try_and<T, E>(a: T, b: T, f: impl Fn(T) -> Result<bool, E>) -> Result<bool, E> {
+    let a = f(a);
+    if matches!(a, Ok(false)) {
+        return Ok(false);
+    }
+    match (a, f(b)) {
+        (_, Ok(false)) | (Ok(false), _) => Ok(false),
+        (Ok(true), Ok(true)) => Ok(true),
+        (Err(e), _) | (_, Err(e)) => Err(e),
+    }
+}
+
+fn try_or<T, E>(a: T, b: T, f: impl Fn(T) -> Result<bool, E>) -> Result<bool, E> {
+    let a = f(a);
+    if matches!(a, Ok(true)) {
+        return Ok(true);
+    }
+    match (a, f(b)) {
+        (_, Ok(true)) | (Ok(true), _) => Ok(true),
+        (Ok(false), Ok(false)) => Ok(false),
+        (Err(e), _) | (_, Err(e)) => Err(e),
+    }
+}
diff --git a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
index aaa66deb2..279a728ea 100644
--- a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
+++ b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
@@ -1,57 +1,60 @@
-pub use self::def_id_forest::DefIdForest;
+//! This module contains logic for determining whether a type is inhabited or
+//! uninhabited. The [`InhabitedPredicate`] type captures the minimum
+//! information needed to determine whether a type is inhabited given a
+//! `ParamEnv` and module ID.
+//!
+//! # Example
+//! ```rust
+//! enum Void {}
+//! mod a {
+//!     pub mod b {
+//!         pub struct SecretlyUninhabited {
+//!             _priv: !,
+//!         }
+//!     }
+//! }
+//!
+//! mod c {
+//!     pub struct AlsoSecretlyUninhabited {
+//!         _priv: Void,
+//!     }
+//!     mod d {
+//!     }
+//! }
+//!
+//! struct Foo {
+//!     x: a::b::SecretlyUninhabited,
+//!     y: c::AlsoSecretlyUninhabited,
+//! }
+//! ```
+//! In this code, the type `Foo` will only be visibly uninhabited inside the
+//! modules `b`, `c` and `d`. Calling `uninhabited_predicate` on `Foo` will
+//! return `NotInModule(b) AND NotInModule(c)`.
+//!
+//! We need this information for pattern-matching on `Foo` or types that contain
+//! `Foo`.
+//!
+//! # Example
+//! ```rust
+//! let foo_result: Result<T, Foo> = ... ;
+//! let Ok(t) = foo_result;
+//! ```
+//! This code should only compile in modules where the uninhabitedness of `Foo`
+//! is visible.
 
-use crate::ty;
 use crate::ty::context::TyCtxt;
-use crate::ty::{AdtDef, FieldDef, Ty, VariantDef};
-use crate::ty::{AdtKind, Visibility};
-use crate::ty::{DefId, SubstsRef};
+use crate::ty::{self, DefId, Ty, VariantDef, Visibility};
 
 use rustc_type_ir::sty::TyKind::*;
 
-mod def_id_forest;
+pub mod inhabited_predicate;
 
-// The methods in this module calculate `DefIdForest`s of modules in which an
-// `AdtDef`/`VariantDef`/`FieldDef` is visibly uninhabited.
-//
-// # Example
-// ```rust
-// enum Void {}
-// mod a {
-//     pub mod b {
-//         pub struct SecretlyUninhabited {
-//             _priv: !,
-//         }
-//     }
-// }
-//
-// mod c {
-//     pub struct AlsoSecretlyUninhabited {
-//         _priv: Void,
-//     }
-//     mod d {
-//     }
-// }
-//
-// struct Foo {
-//     x: a::b::SecretlyUninhabited,
-//     y: c::AlsoSecretlyUninhabited,
-// }
-// ```
-// In this code, the type `Foo` will only be visibly uninhabited inside the
-// modules `b`, `c` and `d`. Calling `uninhabited_from` on `Foo` or its `AdtDef` will
-// return the forest of modules {`b`, `c`->`d`} (represented in a `DefIdForest` by the
-// set {`b`, `c`}).
-//
-// We need this information for pattern-matching on `Foo` or types that contain
-// `Foo`.
-//
-// # Example
-// ```rust
-// let foo_result: Result<T, Foo> = ... ;
-// let Ok(t) = foo_result;
-// ```
-// This code should only compile in modules where the uninhabitedness of `Foo` is
-// visible.
+pub use inhabited_predicate::InhabitedPredicate;
+
+pub(crate) fn provide(providers: &mut ty::query::Providers) {
+    *providers =
+        ty::query::Providers { inhabited_predicate_adt, inhabited_predicate_type, ..*providers };
+}
 
 impl<'tcx> TyCtxt<'tcx> {
     /// Checks whether a type is visibly uninhabited from a particular module.
@@ -100,131 +103,92 @@ impl<'tcx> TyCtxt<'tcx> {
         ty: Ty<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> bool {
-        // To check whether this type is uninhabited at all (not just from the
-        // given node), you could check whether the forest is empty.
-        // ```
-        // forest.is_empty()
-        // ```
-        ty.uninhabited_from(self, param_env).contains(self, module)
+        !ty.inhabited_predicate(self).apply(self, param_env, module)
     }
 }
 
-impl<'tcx> AdtDef<'tcx> {
-    /// Calculates the forest of `DefId`s from which this ADT is visibly uninhabited.
-    fn uninhabited_from(
-        self,
-        tcx: TyCtxt<'tcx>,
-        substs: SubstsRef<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> DefIdForest<'tcx> {
-        // Non-exhaustive ADTs from other crates are always considered inhabited.
-        if self.is_variant_list_non_exhaustive() && !self.did().is_local() {
-            DefIdForest::empty()
-        } else {
-            DefIdForest::intersection(
-                tcx,
-                self.variants()
-                    .iter()
-                    .map(|v| v.uninhabited_from(tcx, substs, self.adt_kind(), param_env)),
-            )
+/// Returns an `InhabitedPredicate` that is generic over type parameters and
+/// requires calling [`InhabitedPredicate::subst`]
+fn inhabited_predicate_adt(tcx: TyCtxt<'_>, def_id: DefId) -> InhabitedPredicate<'_> {
+    if let Some(def_id) = def_id.as_local() {
+        if matches!(tcx.representability(def_id), ty::Representability::Infinite) {
+            return InhabitedPredicate::True;
         }
     }
+    let adt = tcx.adt_def(def_id);
+    InhabitedPredicate::any(
+        tcx,
+        adt.variants().iter().map(|variant| variant.inhabited_predicate(tcx, adt)),
+    )
 }
 
 impl<'tcx> VariantDef {
     /// Calculates the forest of `DefId`s from which this variant is visibly uninhabited.
-    pub fn uninhabited_from(
+    pub fn inhabited_predicate(
         &self,
         tcx: TyCtxt<'tcx>,
-        substs: SubstsRef<'tcx>,
-        adt_kind: AdtKind,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> DefIdForest<'tcx> {
-        let is_enum = match adt_kind {
-            // For now, `union`s are never considered uninhabited.
-            // The precise semantics of inhabitedness with respect to unions is currently undecided.
-            AdtKind::Union => return DefIdForest::empty(),
-            AdtKind::Enum => true,
-            AdtKind::Struct => false,
-        };
-        // Non-exhaustive variants from other crates are always considered inhabited.
+        adt: ty::AdtDef<'_>,
+    ) -> InhabitedPredicate<'tcx> {
+        debug_assert!(!adt.is_union());
         if self.is_field_list_non_exhaustive() && !self.def_id.is_local() {
-            DefIdForest::empty()
-        } else {
-            DefIdForest::union(
-                tcx,
-                self.fields.iter().map(|f| f.uninhabited_from(tcx, substs, is_enum, param_env)),
-            )
+            // Non-exhaustive variants from other crates are always considered inhabited.
+            return InhabitedPredicate::True;
         }
-    }
-}
-
-impl<'tcx> FieldDef {
-    /// Calculates the forest of `DefId`s from which this field is visibly uninhabited.
-    fn uninhabited_from(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        substs: SubstsRef<'tcx>,
-        is_enum: bool,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> DefIdForest<'tcx> {
-        let data_uninhabitedness = move || self.ty(tcx, substs).uninhabited_from(tcx, param_env);
-        if is_enum {
-            data_uninhabitedness()
-        } else {
-            match self.vis {
-                Visibility::Restricted(from) => {
-                    let forest = DefIdForest::from_id(from);
-                    let iter = Some(forest).into_iter().chain(Some(data_uninhabitedness()));
-                    DefIdForest::intersection(tcx, iter)
+        InhabitedPredicate::all(
+            tcx,
+            self.fields.iter().map(|field| {
+                let pred = tcx.type_of(field.did).inhabited_predicate(tcx);
+                if adt.is_enum() {
+                    return pred;
                 }
-                Visibility::Public => data_uninhabitedness(),
-            }
-        }
+                match field.vis {
+                    Visibility::Public => pred,
+                    Visibility::Restricted(from) => {
+                        pred.or(tcx, InhabitedPredicate::NotInModule(from))
+                    }
+                }
+            }),
+        )
     }
 }
 
 impl<'tcx> Ty<'tcx> {
-    /// Calculates the forest of `DefId`s from which this type is visibly uninhabited.
-    fn uninhabited_from(
-        self,
-        tcx: TyCtxt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> DefIdForest<'tcx> {
-        tcx.type_uninhabited_from(param_env.and(self))
+    pub fn inhabited_predicate(self, tcx: TyCtxt<'tcx>) -> InhabitedPredicate<'tcx> {
+        match self.kind() {
+            // For now, union`s are always considered inhabited
+            Adt(adt, _) if adt.is_union() => InhabitedPredicate::True,
+            // Non-exhaustive ADTs from other crates are always considered inhabited
+            Adt(adt, _) if adt.is_variant_list_non_exhaustive() && !adt.did().is_local() => {
+                InhabitedPredicate::True
+            }
+            Never => InhabitedPredicate::False,
+            Param(_) | Projection(_) => InhabitedPredicate::GenericType(self),
+            Tuple(tys) if tys.is_empty() => InhabitedPredicate::True,
+            // use a query for more complex cases
+            Adt(..) | Array(..) | Tuple(_) => tcx.inhabited_predicate_type(self),
+            // references and other types are inhabited
+            _ => InhabitedPredicate::True,
+        }
     }
 }
 
-// Query provider for `type_uninhabited_from`.
-pub(crate) fn type_uninhabited_from<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-) -> DefIdForest<'tcx> {
-    let ty = key.value;
-    let param_env = key.param_env;
+/// N.B. this query should only be called through `Ty::inhabited_predicate`
+fn inhabited_predicate_type<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> InhabitedPredicate<'tcx> {
     match *ty.kind() {
-        Adt(def, substs) => def.uninhabited_from(tcx, substs, param_env),
+        Adt(adt, substs) => tcx.inhabited_predicate_adt(adt.did()).subst(tcx, substs),
 
-        Never => DefIdForest::full(),
-
-        Tuple(ref tys) => {
-            DefIdForest::union(tcx, tys.iter().map(|ty| ty.uninhabited_from(tcx, param_env)))
+        Tuple(tys) => {
+            InhabitedPredicate::all(tcx, tys.iter().map(|ty| ty.inhabited_predicate(tcx)))
         }
 
-        Array(ty, len) => match len.try_eval_usize(tcx, param_env) {
-            Some(0) | None => DefIdForest::empty(),
-            // If the array is definitely non-empty, it's uninhabited if
-            // the type of its elements is uninhabited.
-            Some(1..) => ty.uninhabited_from(tcx, param_env),
+        // If we can evaluate the array length before having a `ParamEnv`, then
+        // we can simplify the predicate. This is an optimization.
+        Array(ty, len) => match len.kind().try_to_machine_usize(tcx) {
+            Some(0) => InhabitedPredicate::True,
+            Some(1..) => ty.inhabited_predicate(tcx),
+            None => ty.inhabited_predicate(tcx).or(tcx, InhabitedPredicate::ConstIsZero(len)),
         },
 
-        // References to uninitialised memory are valid for any type, including
-        // uninhabited types, in unsafe code, so we treat all references as
-        // inhabited.
-        // The precise semantics of inhabitedness with respect to references is currently
-        // undecided.
-        Ref(..) => DefIdForest::empty(),
-
-        _ => DefIdForest::empty(),
+        _ => bug!("unexpected TyKind, use `Ty::inhabited_predicate`"),
     }
 }
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index 9afd66207..6c1414f7b 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -1,9 +1,7 @@
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::ty::print::{FmtPrinter, Printer};
-use crate::ty::subst::{InternalSubsts, Subst};
-use crate::ty::{
-    self, EarlyBinder, SubstsRef, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitable,
-};
+use crate::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitable};
+use crate::ty::{EarlyBinder, InternalSubsts, SubstsRef};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::{CrateNum, DefId};
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 042eeec3f..3312f44c6 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1,41 +1,23 @@
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
 use crate::ty::normalize_erasing_regions::NormalizationError;
-use crate::ty::subst::Subst;
-use crate::ty::{
-    self, layout_sanity_check::sanity_check_layout, subst::SubstsRef, EarlyBinder, ReprOptions, Ty,
-    TyCtxt, TypeVisitable,
-};
+use crate::ty::{self, ReprOptions, Ty, TyCtxt, TypeVisitable};
 use rustc_ast as ast;
 use rustc_attr as attr;
+use rustc_errors::{DiagnosticBuilder, Handler, IntoDiagnostic};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_hir::lang_items::LangItem;
-use rustc_index::bit_set::BitSet;
-use rustc_index::vec::{Idx, IndexVec};
-use rustc_session::{config::OptLevel, DataTypeKind, FieldInfo, SizeKind, VariantInfo};
-use rustc_span::symbol::Symbol;
+use rustc_index::vec::Idx;
+use rustc_session::config::OptLevel;
 use rustc_span::{Span, DUMMY_SP};
-use rustc_target::abi::call::{
-    ArgAbi, ArgAttribute, ArgAttributes, ArgExtension, Conv, FnAbi, PassMode, Reg, RegKind,
-};
+use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::*;
 use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy, Target};
 
-use std::cmp::{self, Ordering};
+use std::cmp::{self};
 use std::fmt;
-use std::iter;
 use std::num::NonZeroUsize;
 use std::ops::Bound;
 
-use rand::{seq::SliceRandom, SeedableRng};
-use rand_xoshiro::Xoshiro128StarStar;
-
-pub fn provide(providers: &mut ty::query::Providers) {
-    *providers =
-        ty::query::Providers { layout_of, fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
-}
-
 pub trait IntegerExt {
     fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx>;
     fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer;
@@ -207,6 +189,31 @@ pub enum LayoutError<'tcx> {
     NormalizationFailure(Ty<'tcx>, NormalizationError<'tcx>),
 }
 
+impl<'a> IntoDiagnostic<'a, !> for LayoutError<'a> {
+    fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, !> {
+        let mut diag = handler.struct_fatal("");
+
+        match self {
+            LayoutError::Unknown(ty) => {
+                diag.set_arg("ty", ty);
+                diag.set_primary_message(rustc_errors::fluent::middle_unknown_layout);
+            }
+            LayoutError::SizeOverflow(ty) => {
+                diag.set_arg("ty", ty);
+                diag.set_primary_message(rustc_errors::fluent::middle_values_too_big);
+            }
+            LayoutError::NormalizationFailure(ty, e) => {
+                diag.set_arg("ty", ty);
+                diag.set_arg("failure_ty", e.get_type_for_failure());
+                diag.set_primary_message(rustc_errors::fluent::middle_cannot_be_normalized);
+            }
+        }
+        diag
+    }
+}
+
+// FIXME: Once the other errors that embed this error have been converted to translateable
+// diagnostics, this Display impl should be removed.
 impl<'tcx> fmt::Display for LayoutError<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
@@ -224,1814 +231,12 @@ impl<'tcx> fmt::Display for LayoutError<'tcx> {
     }
 }
 
-#[instrument(skip(tcx, query), level = "debug")]
-fn layout_of<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
-) -> Result<TyAndLayout<'tcx>, LayoutError<'tcx>> {
-    let (param_env, ty) = query.into_parts();
-    debug!(?ty);
-
-    let param_env = param_env.with_reveal_all_normalized(tcx);
-    let unnormalized_ty = ty;
-
-    // FIXME: We might want to have two different versions of `layout_of`:
-    // One that can be called after typecheck has completed and can use
-    // `normalize_erasing_regions` here and another one that can be called
-    // before typecheck has completed and uses `try_normalize_erasing_regions`.
-    let ty = match tcx.try_normalize_erasing_regions(param_env, ty) {
-        Ok(t) => t,
-        Err(normalization_error) => {
-            return Err(LayoutError::NormalizationFailure(ty, normalization_error));
-        }
-    };
-
-    if ty != unnormalized_ty {
-        // Ensure this layout is also cached for the normalized type.
-        return tcx.layout_of(param_env.and(ty));
-    }
-
-    let cx = LayoutCx { tcx, param_env };
-
-    let layout = cx.layout_of_uncached(ty)?;
-    let layout = TyAndLayout { ty, layout };
-
-    cx.record_layout_for_printing(layout);
-
-    sanity_check_layout(&cx, &layout);
-
-    Ok(layout)
-}
-
 #[derive(Clone, Copy)]
 pub struct LayoutCx<'tcx, C> {
     pub tcx: C,
     pub param_env: ty::ParamEnv<'tcx>,
 }
 
-#[derive(Copy, Clone, Debug)]
-enum StructKind {
-    /// A tuple, closure, or univariant which cannot be coerced to unsized.
-    AlwaysSized,
-    /// A univariant, the last field of which may be coerced to unsized.
-    MaybeUnsized,
-    /// A univariant, but with a prefix of an arbitrary size & alignment (e.g., enum tag).
-    Prefixed(Size, Align),
-}
-
-// Invert a bijective mapping, i.e. `invert(map)[y] = x` if `map[x] = y`.
-// This is used to go between `memory_index` (source field order to memory order)
-// and `inverse_memory_index` (memory order to source field order).
-// See also `FieldsShape::Arbitrary::memory_index` for more details.
-// FIXME(eddyb) build a better abstraction for permutations, if possible.
-fn invert_mapping(map: &[u32]) -> Vec<u32> {
-    let mut inverse = vec![0; map.len()];
-    for i in 0..map.len() {
-        inverse[map[i] as usize] = i as u32;
-    }
-    inverse
-}
-
-impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
-    fn scalar_pair(&self, a: Scalar, b: Scalar) -> LayoutS<'tcx> {
-        let dl = self.data_layout();
-        let b_align = b.align(dl);
-        let align = a.align(dl).max(b_align).max(dl.aggregate_align);
-        let b_offset = a.size(dl).align_to(b_align.abi);
-        let size = (b_offset + b.size(dl)).align_to(align.abi);
-
-        // HACK(nox): We iter on `b` and then `a` because `max_by_key`
-        // returns the last maximum.
-        let largest_niche = Niche::from_scalar(dl, b_offset, b)
-            .into_iter()
-            .chain(Niche::from_scalar(dl, Size::ZERO, a))
-            .max_by_key(|niche| niche.available(dl));
-
-        LayoutS {
-            variants: Variants::Single { index: VariantIdx::new(0) },
-            fields: FieldsShape::Arbitrary {
-                offsets: vec![Size::ZERO, b_offset],
-                memory_index: vec![0, 1],
-            },
-            abi: Abi::ScalarPair(a, b),
-            largest_niche,
-            align,
-            size,
-        }
-    }
-
-    fn univariant_uninterned(
-        &self,
-        ty: Ty<'tcx>,
-        fields: &[TyAndLayout<'_>],
-        repr: &ReprOptions,
-        kind: StructKind,
-    ) -> Result<LayoutS<'tcx>, LayoutError<'tcx>> {
-        let dl = self.data_layout();
-        let pack = repr.pack;
-        if pack.is_some() && repr.align.is_some() {
-            self.tcx.sess.delay_span_bug(DUMMY_SP, "struct cannot be packed and aligned");
-            return Err(LayoutError::Unknown(ty));
-        }
-
-        let mut align = if pack.is_some() { dl.i8_align } else { dl.aggregate_align };
-
-        let mut inverse_memory_index: Vec<u32> = (0..fields.len() as u32).collect();
-
-        let optimize = !repr.inhibit_struct_field_reordering_opt();
-        if optimize {
-            let end =
-                if let StructKind::MaybeUnsized = kind { fields.len() - 1 } else { fields.len() };
-            let optimizing = &mut inverse_memory_index[..end];
-            let field_align = |f: &TyAndLayout<'_>| {
-                if let Some(pack) = pack { f.align.abi.min(pack) } else { f.align.abi }
-            };
-
-            // If `-Z randomize-layout` was enabled for the type definition we can shuffle
-            // the field ordering to try and catch some code making assumptions about layouts
-            // we don't guarantee
-            if repr.can_randomize_type_layout() {
-                // `ReprOptions.layout_seed` is a deterministic seed that we can use to
-                // randomize field ordering with
-                let mut rng = Xoshiro128StarStar::seed_from_u64(repr.field_shuffle_seed);
-
-                // Shuffle the ordering of the fields
-                optimizing.shuffle(&mut rng);
-
-            // Otherwise we just leave things alone and actually optimize the type's fields
-            } else {
-                match kind {
-                    StructKind::AlwaysSized | StructKind::MaybeUnsized => {
-                        optimizing.sort_by_key(|&x| {
-                            // Place ZSTs first to avoid "interesting offsets",
-                            // especially with only one or two non-ZST fields.
-                            let f = &fields[x as usize];
-                            (!f.is_zst(), cmp::Reverse(field_align(f)))
-                        });
-                    }
-
-                    StructKind::Prefixed(..) => {
-                        // Sort in ascending alignment so that the layout stays optimal
-                        // regardless of the prefix
-                        optimizing.sort_by_key(|&x| field_align(&fields[x as usize]));
-                    }
-                }
-
-                // FIXME(Kixiron): We can always shuffle fields within a given alignment class
-                //                 regardless of the status of `-Z randomize-layout`
-            }
-        }
-
-        // inverse_memory_index holds field indices by increasing memory offset.
-        // That is, if field 5 has offset 0, the first element of inverse_memory_index is 5.
-        // We now write field offsets to the corresponding offset slot;
-        // field 5 with offset 0 puts 0 in offsets[5].
-        // At the bottom of this function, we invert `inverse_memory_index` to
-        // produce `memory_index` (see `invert_mapping`).
-
-        let mut sized = true;
-        let mut offsets = vec![Size::ZERO; fields.len()];
-        let mut offset = Size::ZERO;
-        let mut largest_niche = None;
-        let mut largest_niche_available = 0;
-
-        if let StructKind::Prefixed(prefix_size, prefix_align) = kind {
-            let prefix_align =
-                if let Some(pack) = pack { prefix_align.min(pack) } else { prefix_align };
-            align = align.max(AbiAndPrefAlign::new(prefix_align));
-            offset = prefix_size.align_to(prefix_align);
-        }
-
-        for &i in &inverse_memory_index {
-            let field = fields[i as usize];
-            if !sized {
-                self.tcx.sess.delay_span_bug(
-                    DUMMY_SP,
-                    &format!(
-                        "univariant: field #{} of `{}` comes after unsized field",
-                        offsets.len(),
-                        ty
-                    ),
-                );
-            }
-
-            if field.is_unsized() {
-                sized = false;
-            }
-
-            // Invariant: offset < dl.obj_size_bound() <= 1<<61
-            let field_align = if let Some(pack) = pack {
-                field.align.min(AbiAndPrefAlign::new(pack))
-            } else {
-                field.align
-            };
-            offset = offset.align_to(field_align.abi);
-            align = align.max(field_align);
-
-            debug!("univariant offset: {:?} field: {:#?}", offset, field);
-            offsets[i as usize] = offset;
-
-            if let Some(mut niche) = field.largest_niche {
-                let available = niche.available(dl);
-                if available > largest_niche_available {
-                    largest_niche_available = available;
-                    niche.offset += offset;
-                    largest_niche = Some(niche);
-                }
-            }
-
-            offset = offset.checked_add(field.size, dl).ok_or(LayoutError::SizeOverflow(ty))?;
-        }
-
-        if let Some(repr_align) = repr.align {
-            align = align.max(AbiAndPrefAlign::new(repr_align));
-        }
-
-        debug!("univariant min_size: {:?}", offset);
-        let min_size = offset;
-
-        // As stated above, inverse_memory_index holds field indices by increasing offset.
-        // This makes it an already-sorted view of the offsets vec.
-        // To invert it, consider:
-        // If field 5 has offset 0, offsets[0] is 5, and memory_index[5] should be 0.
-        // Field 5 would be the first element, so memory_index is i:
-        // Note: if we didn't optimize, it's already right.
-
-        let memory_index =
-            if optimize { invert_mapping(&inverse_memory_index) } else { inverse_memory_index };
-
-        let size = min_size.align_to(align.abi);
-        let mut abi = Abi::Aggregate { sized };
-
-        // Unpack newtype ABIs and find scalar pairs.
-        if sized && size.bytes() > 0 {
-            // All other fields must be ZSTs.
-            let mut non_zst_fields = fields.iter().enumerate().filter(|&(_, f)| !f.is_zst());
-
-            match (non_zst_fields.next(), non_zst_fields.next(), non_zst_fields.next()) {
-                // We have exactly one non-ZST field.
-                (Some((i, field)), None, None) => {
-                    // Field fills the struct and it has a scalar or scalar pair ABI.
-                    if offsets[i].bytes() == 0 && align.abi == field.align.abi && size == field.size
-                    {
-                        match field.abi {
-                            // For plain scalars, or vectors of them, we can't unpack
-                            // newtypes for `#[repr(C)]`, as that affects C ABIs.
-                            Abi::Scalar(_) | Abi::Vector { .. } if optimize => {
-                                abi = field.abi;
-                            }
-                            // But scalar pairs are Rust-specific and get
-                            // treated as aggregates by C ABIs anyway.
-                            Abi::ScalarPair(..) => {
-                                abi = field.abi;
-                            }
-                            _ => {}
-                        }
-                    }
-                }
-
-                // Two non-ZST fields, and they're both scalars.
-                (Some((i, a)), Some((j, b)), None) => {
-                    match (a.abi, b.abi) {
-                        (Abi::Scalar(a), Abi::Scalar(b)) => {
-                            // Order by the memory placement, not source order.
-                            let ((i, a), (j, b)) = if offsets[i] < offsets[j] {
-                                ((i, a), (j, b))
-                            } else {
-                                ((j, b), (i, a))
-                            };
-                            let pair = self.scalar_pair(a, b);
-                            let pair_offsets = match pair.fields {
-                                FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
-                                    assert_eq!(memory_index, &[0, 1]);
-                                    offsets
-                                }
-                                _ => bug!(),
-                            };
-                            if offsets[i] == pair_offsets[0]
-                                && offsets[j] == pair_offsets[1]
-                                && align == pair.align
-                                && size == pair.size
-                            {
-                                // We can use `ScalarPair` only when it matches our
-                                // already computed layout (including `#[repr(C)]`).
-                                abi = pair.abi;
-                            }
-                        }
-                        _ => {}
-                    }
-                }
-
-                _ => {}
-            }
-        }
-
-        if fields.iter().any(|f| f.abi.is_uninhabited()) {
-            abi = Abi::Uninhabited;
-        }
-
-        Ok(LayoutS {
-            variants: Variants::Single { index: VariantIdx::new(0) },
-            fields: FieldsShape::Arbitrary { offsets, memory_index },
-            abi,
-            largest_niche,
-            align,
-            size,
-        })
-    }
-
-    fn layout_of_uncached(&self, ty: Ty<'tcx>) -> Result<Layout<'tcx>, LayoutError<'tcx>> {
-        let tcx = self.tcx;
-        let param_env = self.param_env;
-        let dl = self.data_layout();
-        let scalar_unit = |value: Primitive| {
-            let size = value.size(dl);
-            assert!(size.bits() <= 128);
-            Scalar::Initialized { value, valid_range: WrappingRange::full(size) }
-        };
-        let scalar =
-            |value: Primitive| tcx.intern_layout(LayoutS::scalar(self, scalar_unit(value)));
-
-        let univariant = |fields: &[TyAndLayout<'_>], repr: &ReprOptions, kind| {
-            Ok(tcx.intern_layout(self.univariant_uninterned(ty, fields, repr, kind)?))
-        };
-        debug_assert!(!ty.has_infer_types_or_consts());
-
-        Ok(match *ty.kind() {
-            // Basic scalars.
-            ty::Bool => tcx.intern_layout(LayoutS::scalar(
-                self,
-                Scalar::Initialized {
-                    value: Int(I8, false),
-                    valid_range: WrappingRange { start: 0, end: 1 },
-                },
-            )),
-            ty::Char => tcx.intern_layout(LayoutS::scalar(
-                self,
-                Scalar::Initialized {
-                    value: Int(I32, false),
-                    valid_range: WrappingRange { start: 0, end: 0x10FFFF },
-                },
-            )),
-            ty::Int(ity) => scalar(Int(Integer::from_int_ty(dl, ity), true)),
-            ty::Uint(ity) => scalar(Int(Integer::from_uint_ty(dl, ity), false)),
-            ty::Float(fty) => scalar(match fty {
-                ty::FloatTy::F32 => F32,
-                ty::FloatTy::F64 => F64,
-            }),
-            ty::FnPtr(_) => {
-                let mut ptr = scalar_unit(Pointer);
-                ptr.valid_range_mut().start = 1;
-                tcx.intern_layout(LayoutS::scalar(self, ptr))
-            }
-
-            // The never type.
-            ty::Never => tcx.intern_layout(LayoutS {
-                variants: Variants::Single { index: VariantIdx::new(0) },
-                fields: FieldsShape::Primitive,
-                abi: Abi::Uninhabited,
-                largest_niche: None,
-                align: dl.i8_align,
-                size: Size::ZERO,
-            }),
-
-            // Potentially-wide pointers.
-            ty::Ref(_, pointee, _) | ty::RawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
-                let mut data_ptr = scalar_unit(Pointer);
-                if !ty.is_unsafe_ptr() {
-                    data_ptr.valid_range_mut().start = 1;
-                }
-
-                let pointee = tcx.normalize_erasing_regions(param_env, pointee);
-                if pointee.is_sized(tcx.at(DUMMY_SP), param_env) {
-                    return Ok(tcx.intern_layout(LayoutS::scalar(self, data_ptr)));
-                }
-
-                let unsized_part = tcx.struct_tail_erasing_lifetimes(pointee, param_env);
-                let metadata = match unsized_part.kind() {
-                    ty::Foreign(..) => {
-                        return Ok(tcx.intern_layout(LayoutS::scalar(self, data_ptr)));
-                    }
-                    ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)),
-                    ty::Dynamic(..) => {
-                        let mut vtable = scalar_unit(Pointer);
-                        vtable.valid_range_mut().start = 1;
-                        vtable
-                    }
-                    _ => return Err(LayoutError::Unknown(unsized_part)),
-                };
-
-                // Effectively a (ptr, meta) tuple.
-                tcx.intern_layout(self.scalar_pair(data_ptr, metadata))
-            }
-
-            ty::Dynamic(_, _, ty::DynStar) => {
-                let mut data = scalar_unit(Int(dl.ptr_sized_integer(), false));
-                data.valid_range_mut().start = 0;
-                let mut vtable = scalar_unit(Pointer);
-                vtable.valid_range_mut().start = 1;
-                tcx.intern_layout(self.scalar_pair(data, vtable))
-            }
-
-            // Arrays and slices.
-            ty::Array(element, mut count) => {
-                if count.has_projections() {
-                    count = tcx.normalize_erasing_regions(param_env, count);
-                    if count.has_projections() {
-                        return Err(LayoutError::Unknown(ty));
-                    }
-                }
-
-                let count = count.try_eval_usize(tcx, param_env).ok_or(LayoutError::Unknown(ty))?;
-                let element = self.layout_of(element)?;
-                let size =
-                    element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow(ty))?;
-
-                let abi =
-                    if count != 0 && tcx.conservative_is_privately_uninhabited(param_env.and(ty)) {
-                        Abi::Uninhabited
-                    } else {
-                        Abi::Aggregate { sized: true }
-                    };
-
-                let largest_niche = if count != 0 { element.largest_niche } else { None };
-
-                tcx.intern_layout(LayoutS {
-                    variants: Variants::Single { index: VariantIdx::new(0) },
-                    fields: FieldsShape::Array { stride: element.size, count },
-                    abi,
-                    largest_niche,
-                    align: element.align,
-                    size,
-                })
-            }
-            ty::Slice(element) => {
-                let element = self.layout_of(element)?;
-                tcx.intern_layout(LayoutS {
-                    variants: Variants::Single { index: VariantIdx::new(0) },
-                    fields: FieldsShape::Array { stride: element.size, count: 0 },
-                    abi: Abi::Aggregate { sized: false },
-                    largest_niche: None,
-                    align: element.align,
-                    size: Size::ZERO,
-                })
-            }
-            ty::Str => tcx.intern_layout(LayoutS {
-                variants: Variants::Single { index: VariantIdx::new(0) },
-                fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
-                abi: Abi::Aggregate { sized: false },
-                largest_niche: None,
-                align: dl.i8_align,
-                size: Size::ZERO,
-            }),
-
-            // Odd unit types.
-            ty::FnDef(..) => univariant(&[], &ReprOptions::default(), StructKind::AlwaysSized)?,
-            ty::Dynamic(_, _, ty::Dyn) | ty::Foreign(..) => {
-                let mut unit = self.univariant_uninterned(
-                    ty,
-                    &[],
-                    &ReprOptions::default(),
-                    StructKind::AlwaysSized,
-                )?;
-                match unit.abi {
-                    Abi::Aggregate { ref mut sized } => *sized = false,
-                    _ => bug!(),
-                }
-                tcx.intern_layout(unit)
-            }
-
-            ty::Generator(def_id, substs, _) => self.generator_layout(ty, def_id, substs)?,
-
-            ty::Closure(_, ref substs) => {
-                let tys = substs.as_closure().upvar_tys();
-                univariant(
-                    &tys.map(|ty| self.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
-                    &ReprOptions::default(),
-                    StructKind::AlwaysSized,
-                )?
-            }
-
-            ty::Tuple(tys) => {
-                let kind =
-                    if tys.len() == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized };
-
-                univariant(
-                    &tys.iter().map(|k| self.layout_of(k)).collect::<Result<Vec<_>, _>>()?,
-                    &ReprOptions::default(),
-                    kind,
-                )?
-            }
-
-            // SIMD vector types.
-            ty::Adt(def, substs) if def.repr().simd() => {
-                if !def.is_struct() {
-                    // Should have yielded E0517 by now.
-                    tcx.sess.delay_span_bug(
-                        DUMMY_SP,
-                        "#[repr(simd)] was applied to an ADT that is not a struct",
-                    );
-                    return Err(LayoutError::Unknown(ty));
-                }
-
-                // Supported SIMD vectors are homogeneous ADTs with at least one field:
-                //
-                // * #[repr(simd)] struct S(T, T, T, T);
-                // * #[repr(simd)] struct S { x: T, y: T, z: T, w: T }
-                // * #[repr(simd)] struct S([T; 4])
-                //
-                // where T is a primitive scalar (integer/float/pointer).
-
-                // SIMD vectors with zero fields are not supported.
-                // (should be caught by typeck)
-                if def.non_enum_variant().fields.is_empty() {
-                    tcx.sess.fatal(&format!("monomorphising SIMD type `{}` of zero length", ty));
-                }
-
-                // Type of the first ADT field:
-                let f0_ty = def.non_enum_variant().fields[0].ty(tcx, substs);
-
-                // Heterogeneous SIMD vectors are not supported:
-                // (should be caught by typeck)
-                for fi in &def.non_enum_variant().fields {
-                    if fi.ty(tcx, substs) != f0_ty {
-                        tcx.sess.fatal(&format!("monomorphising heterogeneous SIMD type `{}`", ty));
-                    }
-                }
-
-                // The element type and number of elements of the SIMD vector
-                // are obtained from:
-                //
-                // * the element type and length of the single array field, if
-                // the first field is of array type, or
-                //
-                // * the homogeneous field type and the number of fields.
-                let (e_ty, e_len, is_array) = if let ty::Array(e_ty, _) = f0_ty.kind() {
-                    // First ADT field is an array:
-
-                    // SIMD vectors with multiple array fields are not supported:
-                    // (should be caught by typeck)
-                    if def.non_enum_variant().fields.len() != 1 {
-                        tcx.sess.fatal(&format!(
-                            "monomorphising SIMD type `{}` with more than one array field",
-                            ty
-                        ));
-                    }
-
-                    // Extract the number of elements from the layout of the array field:
-                    let FieldsShape::Array { count, .. } = self.layout_of(f0_ty)?.layout.fields() else {
-                        return Err(LayoutError::Unknown(ty));
-                    };
-
-                    (*e_ty, *count, true)
-                } else {
-                    // First ADT field is not an array:
-                    (f0_ty, def.non_enum_variant().fields.len() as _, false)
-                };
-
-                // SIMD vectors of zero length are not supported.
-                // Additionally, lengths are capped at 2^16 as a fixed maximum backends must
-                // support.
-                //
-                // Can't be caught in typeck if the array length is generic.
-                if e_len == 0 {
-                    tcx.sess.fatal(&format!("monomorphising SIMD type `{}` of zero length", ty));
-                } else if e_len > MAX_SIMD_LANES {
-                    tcx.sess.fatal(&format!(
-                        "monomorphising SIMD type `{}` of length greater than {}",
-                        ty, MAX_SIMD_LANES,
-                    ));
-                }
-
-                // Compute the ABI of the element type:
-                let e_ly = self.layout_of(e_ty)?;
-                let Abi::Scalar(e_abi) = e_ly.abi else {
-                    // This error isn't caught in typeck, e.g., if
-                    // the element type of the vector is generic.
-                    tcx.sess.fatal(&format!(
-                        "monomorphising SIMD type `{}` with a non-primitive-scalar \
-                        (integer/float/pointer) element type `{}`",
-                        ty, e_ty
-                    ))
-                };
-
-                // Compute the size and alignment of the vector:
-                let size = e_ly.size.checked_mul(e_len, dl).ok_or(LayoutError::SizeOverflow(ty))?;
-                let align = dl.vector_align(size);
-                let size = size.align_to(align.abi);
-
-                // Compute the placement of the vector fields:
-                let fields = if is_array {
-                    FieldsShape::Arbitrary { offsets: vec![Size::ZERO], memory_index: vec![0] }
-                } else {
-                    FieldsShape::Array { stride: e_ly.size, count: e_len }
-                };
-
-                tcx.intern_layout(LayoutS {
-                    variants: Variants::Single { index: VariantIdx::new(0) },
-                    fields,
-                    abi: Abi::Vector { element: e_abi, count: e_len },
-                    largest_niche: e_ly.largest_niche,
-                    size,
-                    align,
-                })
-            }
-
-            // ADTs.
-            ty::Adt(def, substs) => {
-                // Cache the field layouts.
-                let variants = def
-                    .variants()
-                    .iter()
-                    .map(|v| {
-                        v.fields
-                            .iter()
-                            .map(|field| self.layout_of(field.ty(tcx, substs)))
-                            .collect::<Result<Vec<_>, _>>()
-                    })
-                    .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
-
-                if def.is_union() {
-                    if def.repr().pack.is_some() && def.repr().align.is_some() {
-                        self.tcx.sess.delay_span_bug(
-                            tcx.def_span(def.did()),
-                            "union cannot be packed and aligned",
-                        );
-                        return Err(LayoutError::Unknown(ty));
-                    }
-
-                    let mut align =
-                        if def.repr().pack.is_some() { dl.i8_align } else { dl.aggregate_align };
-
-                    if let Some(repr_align) = def.repr().align {
-                        align = align.max(AbiAndPrefAlign::new(repr_align));
-                    }
-
-                    let optimize = !def.repr().inhibit_union_abi_opt();
-                    let mut size = Size::ZERO;
-                    let mut abi = Abi::Aggregate { sized: true };
-                    let index = VariantIdx::new(0);
-                    for field in &variants[index] {
-                        assert!(!field.is_unsized());
-                        align = align.max(field.align);
-
-                        // If all non-ZST fields have the same ABI, forward this ABI
-                        if optimize && !field.is_zst() {
-                            // Discard valid range information and allow undef
-                            let field_abi = match field.abi {
-                                Abi::Scalar(x) => Abi::Scalar(x.to_union()),
-                                Abi::ScalarPair(x, y) => {
-                                    Abi::ScalarPair(x.to_union(), y.to_union())
-                                }
-                                Abi::Vector { element: x, count } => {
-                                    Abi::Vector { element: x.to_union(), count }
-                                }
-                                Abi::Uninhabited | Abi::Aggregate { .. } => {
-                                    Abi::Aggregate { sized: true }
-                                }
-                            };
-
-                            if size == Size::ZERO {
-                                // first non ZST: initialize 'abi'
-                                abi = field_abi;
-                            } else if abi != field_abi {
-                                // different fields have different ABI: reset to Aggregate
-                                abi = Abi::Aggregate { sized: true };
-                            }
-                        }
-
-                        size = cmp::max(size, field.size);
-                    }
-
-                    if let Some(pack) = def.repr().pack {
-                        align = align.min(AbiAndPrefAlign::new(pack));
-                    }
-
-                    return Ok(tcx.intern_layout(LayoutS {
-                        variants: Variants::Single { index },
-                        fields: FieldsShape::Union(
-                            NonZeroUsize::new(variants[index].len())
-                                .ok_or(LayoutError::Unknown(ty))?,
-                        ),
-                        abi,
-                        largest_niche: None,
-                        align,
-                        size: size.align_to(align.abi),
-                    }));
-                }
-
-                // A variant is absent if it's uninhabited and only has ZST fields.
-                // Present uninhabited variants only require space for their fields,
-                // but *not* an encoding of the discriminant (e.g., a tag value).
-                // See issue #49298 for more details on the need to leave space
-                // for non-ZST uninhabited data (mostly partial initialization).
-                let absent = |fields: &[TyAndLayout<'_>]| {
-                    let uninhabited = fields.iter().any(|f| f.abi.is_uninhabited());
-                    let is_zst = fields.iter().all(|f| f.is_zst());
-                    uninhabited && is_zst
-                };
-                let (present_first, present_second) = {
-                    let mut present_variants = variants
-                        .iter_enumerated()
-                        .filter_map(|(i, v)| if absent(v) { None } else { Some(i) });
-                    (present_variants.next(), present_variants.next())
-                };
-                let present_first = match present_first {
-                    Some(present_first) => present_first,
-                    // Uninhabited because it has no variants, or only absent ones.
-                    None if def.is_enum() => {
-                        return Ok(tcx.layout_of(param_env.and(tcx.types.never))?.layout);
-                    }
-                    // If it's a struct, still compute a layout so that we can still compute the
-                    // field offsets.
-                    None => VariantIdx::new(0),
-                };
-
-                let is_struct = !def.is_enum() ||
-                    // Only one variant is present.
-                    (present_second.is_none() &&
-                    // Representation optimizations are allowed.
-                    !def.repr().inhibit_enum_layout_opt());
-                if is_struct {
-                    // Struct, or univariant enum equivalent to a struct.
-                    // (Typechecking will reject discriminant-sizing attrs.)
-
-                    let v = present_first;
-                    let kind = if def.is_enum() || variants[v].is_empty() {
-                        StructKind::AlwaysSized
-                    } else {
-                        let param_env = tcx.param_env(def.did());
-                        let last_field = def.variant(v).fields.last().unwrap();
-                        let always_sized =
-                            tcx.type_of(last_field.did).is_sized(tcx.at(DUMMY_SP), param_env);
-                        if !always_sized {
-                            StructKind::MaybeUnsized
-                        } else {
-                            StructKind::AlwaysSized
-                        }
-                    };
-
-                    let mut st = self.univariant_uninterned(ty, &variants[v], &def.repr(), kind)?;
-                    st.variants = Variants::Single { index: v };
-
-                    if def.is_unsafe_cell() {
-                        let hide_niches = |scalar: &mut _| match scalar {
-                            Scalar::Initialized { value, valid_range } => {
-                                *valid_range = WrappingRange::full(value.size(dl))
-                            }
-                            // Already doesn't have any niches
-                            Scalar::Union { .. } => {}
-                        };
-                        match &mut st.abi {
-                            Abi::Uninhabited => {}
-                            Abi::Scalar(scalar) => hide_niches(scalar),
-                            Abi::ScalarPair(a, b) => {
-                                hide_niches(a);
-                                hide_niches(b);
-                            }
-                            Abi::Vector { element, count: _ } => hide_niches(element),
-                            Abi::Aggregate { sized: _ } => {}
-                        }
-                        st.largest_niche = None;
-                        return Ok(tcx.intern_layout(st));
-                    }
-
-                    let (start, end) = self.tcx.layout_scalar_valid_range(def.did());
-                    match st.abi {
-                        Abi::Scalar(ref mut scalar) | Abi::ScalarPair(ref mut scalar, _) => {
-                            // the asserts ensure that we are not using the
-                            // `#[rustc_layout_scalar_valid_range(n)]`
-                            // attribute to widen the range of anything as that would probably
-                            // result in UB somewhere
-                            // FIXME(eddyb) the asserts are probably not needed,
-                            // as larger validity ranges would result in missed
-                            // optimizations, *not* wrongly assuming the inner
-                            // value is valid. e.g. unions enlarge validity ranges,
-                            // because the values may be uninitialized.
-                            if let Bound::Included(start) = start {
-                                // FIXME(eddyb) this might be incorrect - it doesn't
-                                // account for wrap-around (end < start) ranges.
-                                let valid_range = scalar.valid_range_mut();
-                                assert!(valid_range.start <= start);
-                                valid_range.start = start;
-                            }
-                            if let Bound::Included(end) = end {
-                                // FIXME(eddyb) this might be incorrect - it doesn't
-                                // account for wrap-around (end < start) ranges.
-                                let valid_range = scalar.valid_range_mut();
-                                assert!(valid_range.end >= end);
-                                valid_range.end = end;
-                            }
-
-                            // Update `largest_niche` if we have introduced a larger niche.
-                            let niche = Niche::from_scalar(dl, Size::ZERO, *scalar);
-                            if let Some(niche) = niche {
-                                match st.largest_niche {
-                                    Some(largest_niche) => {
-                                        // Replace the existing niche even if they're equal,
-                                        // because this one is at a lower offset.
-                                        if largest_niche.available(dl) <= niche.available(dl) {
-                                            st.largest_niche = Some(niche);
-                                        }
-                                    }
-                                    None => st.largest_niche = Some(niche),
-                                }
-                            }
-                        }
-                        _ => assert!(
-                            start == Bound::Unbounded && end == Bound::Unbounded,
-                            "nonscalar layout for layout_scalar_valid_range type {:?}: {:#?}",
-                            def,
-                            st,
-                        ),
-                    }
-
-                    return Ok(tcx.intern_layout(st));
-                }
-
-                // At this point, we have handled all unions and
-                // structs. (We have also handled univariant enums
-                // that allow representation optimization.)
-                assert!(def.is_enum());
-
-                // Until we've decided whether to use the tagged or
-                // niche filling LayoutS, we don't want to intern the
-                // variant layouts, so we can't store them in the
-                // overall LayoutS. Store the overall LayoutS
-                // and the variant LayoutSs here until then.
-                struct TmpLayout<'tcx> {
-                    layout: LayoutS<'tcx>,
-                    variants: IndexVec<VariantIdx, LayoutS<'tcx>>,
-                }
-
-                let calculate_niche_filling_layout =
-                    || -> Result<Option<TmpLayout<'tcx>>, LayoutError<'tcx>> {
-                        // The current code for niche-filling relies on variant indices
-                        // instead of actual discriminants, so enums with
-                        // explicit discriminants (RFC #2363) would misbehave.
-                        if def.repr().inhibit_enum_layout_opt()
-                            || def
-                                .variants()
-                                .iter_enumerated()
-                                .any(|(i, v)| v.discr != ty::VariantDiscr::Relative(i.as_u32()))
-                        {
-                            return Ok(None);
-                        }
-
-                        if variants.len() < 2 {
-                            return Ok(None);
-                        }
-
-                        let mut align = dl.aggregate_align;
-                        let mut variant_layouts = variants
-                            .iter_enumerated()
-                            .map(|(j, v)| {
-                                let mut st = self.univariant_uninterned(
-                                    ty,
-                                    v,
-                                    &def.repr(),
-                                    StructKind::AlwaysSized,
-                                )?;
-                                st.variants = Variants::Single { index: j };
-
-                                align = align.max(st.align);
-
-                                Ok(st)
-                            })
-                            .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
-
-                        let largest_variant_index = match variant_layouts
-                            .iter_enumerated()
-                            .max_by_key(|(_i, layout)| layout.size.bytes())
-                            .map(|(i, _layout)| i)
-                        {
-                            None => return Ok(None),
-                            Some(i) => i,
-                        };
-
-                        let all_indices = VariantIdx::new(0)..=VariantIdx::new(variants.len() - 1);
-                        let needs_disc = |index: VariantIdx| {
-                            index != largest_variant_index && !absent(&variants[index])
-                        };
-                        let niche_variants = all_indices.clone().find(|v| needs_disc(*v)).unwrap()
-                            ..=all_indices.rev().find(|v| needs_disc(*v)).unwrap();
-
-                        let count = niche_variants.size_hint().1.unwrap() as u128;
-
-                        // Find the field with the largest niche
-                        let (field_index, niche, (niche_start, niche_scalar)) = match variants
-                            [largest_variant_index]
-                            .iter()
-                            .enumerate()
-                            .filter_map(|(j, field)| Some((j, field.largest_niche?)))
-                            .max_by_key(|(_, niche)| niche.available(dl))
-                            .and_then(|(j, niche)| Some((j, niche, niche.reserve(self, count)?)))
-                        {
-                            None => return Ok(None),
-                            Some(x) => x,
-                        };
-
-                        let niche_offset = niche.offset
-                            + variant_layouts[largest_variant_index].fields.offset(field_index);
-                        let niche_size = niche.value.size(dl);
-                        let size = variant_layouts[largest_variant_index].size.align_to(align.abi);
-
-                        let all_variants_fit =
-                            variant_layouts.iter_enumerated_mut().all(|(i, layout)| {
-                                if i == largest_variant_index {
-                                    return true;
-                                }
-
-                                layout.largest_niche = None;
-
-                                if layout.size <= niche_offset {
-                                    // This variant will fit before the niche.
-                                    return true;
-                                }
-
-                                // Determine if it'll fit after the niche.
-                                let this_align = layout.align.abi;
-                                let this_offset = (niche_offset + niche_size).align_to(this_align);
-
-                                if this_offset + layout.size > size {
-                                    return false;
-                                }
-
-                                // It'll fit, but we need to make some adjustments.
-                                match layout.fields {
-                                    FieldsShape::Arbitrary { ref mut offsets, .. } => {
-                                        for (j, offset) in offsets.iter_mut().enumerate() {
-                                            if !variants[i][j].is_zst() {
-                                                *offset += this_offset;
-                                            }
-                                        }
-                                    }
-                                    _ => {
-                                        panic!("Layout of fields should be Arbitrary for variants")
-                                    }
-                                }
-
-                                // It can't be a Scalar or ScalarPair because the offset isn't 0.
-                                if !layout.abi.is_uninhabited() {
-                                    layout.abi = Abi::Aggregate { sized: true };
-                                }
-                                layout.size += this_offset;
-
-                                true
-                            });
-
-                        if !all_variants_fit {
-                            return Ok(None);
-                        }
-
-                        let largest_niche = Niche::from_scalar(dl, niche_offset, niche_scalar);
-
-                        let others_zst = variant_layouts.iter_enumerated().all(|(i, layout)| {
-                            i == largest_variant_index || layout.size == Size::ZERO
-                        });
-                        let same_size = size == variant_layouts[largest_variant_index].size;
-                        let same_align = align == variant_layouts[largest_variant_index].align;
-
-                        let abi = if variant_layouts.iter().all(|v| v.abi.is_uninhabited()) {
-                            Abi::Uninhabited
-                        } else if same_size && same_align && others_zst {
-                            match variant_layouts[largest_variant_index].abi {
-                                // When the total alignment and size match, we can use the
-                                // same ABI as the scalar variant with the reserved niche.
-                                Abi::Scalar(_) => Abi::Scalar(niche_scalar),
-                                Abi::ScalarPair(first, second) => {
-                                    // Only the niche is guaranteed to be initialised,
-                                    // so use union layouts for the other primitive.
-                                    if niche_offset == Size::ZERO {
-                                        Abi::ScalarPair(niche_scalar, second.to_union())
-                                    } else {
-                                        Abi::ScalarPair(first.to_union(), niche_scalar)
-                                    }
-                                }
-                                _ => Abi::Aggregate { sized: true },
-                            }
-                        } else {
-                            Abi::Aggregate { sized: true }
-                        };
-
-                        let layout = LayoutS {
-                            variants: Variants::Multiple {
-                                tag: niche_scalar,
-                                tag_encoding: TagEncoding::Niche {
-                                    untagged_variant: largest_variant_index,
-                                    niche_variants,
-                                    niche_start,
-                                },
-                                tag_field: 0,
-                                variants: IndexVec::new(),
-                            },
-                            fields: FieldsShape::Arbitrary {
-                                offsets: vec![niche_offset],
-                                memory_index: vec![0],
-                            },
-                            abi,
-                            largest_niche,
-                            size,
-                            align,
-                        };
-
-                        Ok(Some(TmpLayout { layout, variants: variant_layouts }))
-                    };
-
-                let niche_filling_layout = calculate_niche_filling_layout()?;
-
-                let (mut min, mut max) = (i128::MAX, i128::MIN);
-                let discr_type = def.repr().discr_type();
-                let bits = Integer::from_attr(self, discr_type).size().bits();
-                for (i, discr) in def.discriminants(tcx) {
-                    if variants[i].iter().any(|f| f.abi.is_uninhabited()) {
-                        continue;
-                    }
-                    let mut x = discr.val as i128;
-                    if discr_type.is_signed() {
-                        // sign extend the raw representation to be an i128
-                        x = (x << (128 - bits)) >> (128 - bits);
-                    }
-                    if x < min {
-                        min = x;
-                    }
-                    if x > max {
-                        max = x;
-                    }
-                }
-                // We might have no inhabited variants, so pretend there's at least one.
-                if (min, max) == (i128::MAX, i128::MIN) {
-                    min = 0;
-                    max = 0;
-                }
-                assert!(min <= max, "discriminant range is {}...{}", min, max);
-                let (min_ity, signed) = Integer::repr_discr(tcx, ty, &def.repr(), min, max);
-
-                let mut align = dl.aggregate_align;
-                let mut size = Size::ZERO;
-
-                // We're interested in the smallest alignment, so start large.
-                let mut start_align = Align::from_bytes(256).unwrap();
-                assert_eq!(Integer::for_align(dl, start_align), None);
-
-                // repr(C) on an enum tells us to make a (tag, union) layout,
-                // so we need to grow the prefix alignment to be at least
-                // the alignment of the union. (This value is used both for
-                // determining the alignment of the overall enum, and the
-                // determining the alignment of the payload after the tag.)
-                let mut prefix_align = min_ity.align(dl).abi;
-                if def.repr().c() {
-                    for fields in &variants {
-                        for field in fields {
-                            prefix_align = prefix_align.max(field.align.abi);
-                        }
-                    }
-                }
-
-                // Create the set of structs that represent each variant.
-                let mut layout_variants = variants
-                    .iter_enumerated()
-                    .map(|(i, field_layouts)| {
-                        let mut st = self.univariant_uninterned(
-                            ty,
-                            &field_layouts,
-                            &def.repr(),
-                            StructKind::Prefixed(min_ity.size(), prefix_align),
-                        )?;
-                        st.variants = Variants::Single { index: i };
-                        // Find the first field we can't move later
-                        // to make room for a larger discriminant.
-                        for field in
-                            st.fields.index_by_increasing_offset().map(|j| field_layouts[j])
-                        {
-                            if !field.is_zst() || field.align.abi.bytes() != 1 {
-                                start_align = start_align.min(field.align.abi);
-                                break;
-                            }
-                        }
-                        size = cmp::max(size, st.size);
-                        align = align.max(st.align);
-                        Ok(st)
-                    })
-                    .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
-
-                // Align the maximum variant size to the largest alignment.
-                size = size.align_to(align.abi);
-
-                if size.bytes() >= dl.obj_size_bound() {
-                    return Err(LayoutError::SizeOverflow(ty));
-                }
-
-                let typeck_ity = Integer::from_attr(dl, def.repr().discr_type());
-                if typeck_ity < min_ity {
-                    // It is a bug if Layout decided on a greater discriminant size than typeck for
-                    // some reason at this point (based on values discriminant can take on). Mostly
-                    // because this discriminant will be loaded, and then stored into variable of
-                    // type calculated by typeck. Consider such case (a bug): typeck decided on
-                    // byte-sized discriminant, but layout thinks we need a 16-bit to store all
-                    // discriminant values. That would be a bug, because then, in codegen, in order
-                    // to store this 16-bit discriminant into 8-bit sized temporary some of the
-                    // space necessary to represent would have to be discarded (or layout is wrong
-                    // on thinking it needs 16 bits)
-                    bug!(
-                        "layout decided on a larger discriminant type ({:?}) than typeck ({:?})",
-                        min_ity,
-                        typeck_ity
-                    );
-                    // However, it is fine to make discr type however large (as an optimisation)
-                    // after this point – we’ll just truncate the value we load in codegen.
-                }
-
-                // Check to see if we should use a different type for the
-                // discriminant. We can safely use a type with the same size
-                // as the alignment of the first field of each variant.
-                // We increase the size of the discriminant to avoid LLVM copying
-                // padding when it doesn't need to. This normally causes unaligned
-                // load/stores and excessive memcpy/memset operations. By using a
-                // bigger integer size, LLVM can be sure about its contents and
-                // won't be so conservative.
-
-                // Use the initial field alignment
-                let mut ity = if def.repr().c() || def.repr().int.is_some() {
-                    min_ity
-                } else {
-                    Integer::for_align(dl, start_align).unwrap_or(min_ity)
-                };
-
-                // If the alignment is not larger than the chosen discriminant size,
-                // don't use the alignment as the final size.
-                if ity <= min_ity {
-                    ity = min_ity;
-                } else {
-                    // Patch up the variants' first few fields.
-                    let old_ity_size = min_ity.size();
-                    let new_ity_size = ity.size();
-                    for variant in &mut layout_variants {
-                        match variant.fields {
-                            FieldsShape::Arbitrary { ref mut offsets, .. } => {
-                                for i in offsets {
-                                    if *i <= old_ity_size {
-                                        assert_eq!(*i, old_ity_size);
-                                        *i = new_ity_size;
-                                    }
-                                }
-                                // We might be making the struct larger.
-                                if variant.size <= old_ity_size {
-                                    variant.size = new_ity_size;
-                                }
-                            }
-                            _ => bug!(),
-                        }
-                    }
-                }
-
-                let tag_mask = ity.size().unsigned_int_max();
-                let tag = Scalar::Initialized {
-                    value: Int(ity, signed),
-                    valid_range: WrappingRange {
-                        start: (min as u128 & tag_mask),
-                        end: (max as u128 & tag_mask),
-                    },
-                };
-                let mut abi = Abi::Aggregate { sized: true };
-
-                if layout_variants.iter().all(|v| v.abi.is_uninhabited()) {
-                    abi = Abi::Uninhabited;
-                } else if tag.size(dl) == size {
-                    // Make sure we only use scalar layout when the enum is entirely its
-                    // own tag (i.e. it has no padding nor any non-ZST variant fields).
-                    abi = Abi::Scalar(tag);
-                } else {
-                    // Try to use a ScalarPair for all tagged enums.
-                    let mut common_prim = None;
-                    let mut common_prim_initialized_in_all_variants = true;
-                    for (field_layouts, layout_variant) in iter::zip(&variants, &layout_variants) {
-                        let FieldsShape::Arbitrary { ref offsets, .. } = layout_variant.fields else {
-                            bug!();
-                        };
-                        let mut fields =
-                            iter::zip(field_layouts, offsets).filter(|p| !p.0.is_zst());
-                        let (field, offset) = match (fields.next(), fields.next()) {
-                            (None, None) => {
-                                common_prim_initialized_in_all_variants = false;
-                                continue;
-                            }
-                            (Some(pair), None) => pair,
-                            _ => {
-                                common_prim = None;
-                                break;
-                            }
-                        };
-                        let prim = match field.abi {
-                            Abi::Scalar(scalar) => {
-                                common_prim_initialized_in_all_variants &=
-                                    matches!(scalar, Scalar::Initialized { .. });
-                                scalar.primitive()
-                            }
-                            _ => {
-                                common_prim = None;
-                                break;
-                            }
-                        };
-                        if let Some(pair) = common_prim {
-                            // This is pretty conservative. We could go fancier
-                            // by conflating things like i32 and u32, or even
-                            // realising that (u8, u8) could just cohabit with
-                            // u16 or even u32.
-                            if pair != (prim, offset) {
-                                common_prim = None;
-                                break;
-                            }
-                        } else {
-                            common_prim = Some((prim, offset));
-                        }
-                    }
-                    if let Some((prim, offset)) = common_prim {
-                        let prim_scalar = if common_prim_initialized_in_all_variants {
-                            scalar_unit(prim)
-                        } else {
-                            // Common prim might be uninit.
-                            Scalar::Union { value: prim }
-                        };
-                        let pair = self.scalar_pair(tag, prim_scalar);
-                        let pair_offsets = match pair.fields {
-                            FieldsShape::Arbitrary { ref offsets, ref memory_index } => {
-                                assert_eq!(memory_index, &[0, 1]);
-                                offsets
-                            }
-                            _ => bug!(),
-                        };
-                        if pair_offsets[0] == Size::ZERO
-                            && pair_offsets[1] == *offset
-                            && align == pair.align
-                            && size == pair.size
-                        {
-                            // We can use `ScalarPair` only when it matches our
-                            // already computed layout (including `#[repr(C)]`).
-                            abi = pair.abi;
-                        }
-                    }
-                }
-
-                // If we pick a "clever" (by-value) ABI, we might have to adjust the ABI of the
-                // variants to ensure they are consistent. This is because a downcast is
-                // semantically a NOP, and thus should not affect layout.
-                if matches!(abi, Abi::Scalar(..) | Abi::ScalarPair(..)) {
-                    for variant in &mut layout_variants {
-                        // We only do this for variants with fields; the others are not accessed anyway.
-                        // Also do not overwrite any already existing "clever" ABIs.
-                        if variant.fields.count() > 0
-                            && matches!(variant.abi, Abi::Aggregate { .. })
-                        {
-                            variant.abi = abi;
-                            // Also need to bump up the size and alignment, so that the entire value fits in here.
-                            variant.size = cmp::max(variant.size, size);
-                            variant.align.abi = cmp::max(variant.align.abi, align.abi);
-                        }
-                    }
-                }
-
-                let largest_niche = Niche::from_scalar(dl, Size::ZERO, tag);
-
-                let tagged_layout = LayoutS {
-                    variants: Variants::Multiple {
-                        tag,
-                        tag_encoding: TagEncoding::Direct,
-                        tag_field: 0,
-                        variants: IndexVec::new(),
-                    },
-                    fields: FieldsShape::Arbitrary {
-                        offsets: vec![Size::ZERO],
-                        memory_index: vec![0],
-                    },
-                    largest_niche,
-                    abi,
-                    align,
-                    size,
-                };
-
-                let tagged_layout = TmpLayout { layout: tagged_layout, variants: layout_variants };
-
-                let mut best_layout = match (tagged_layout, niche_filling_layout) {
-                    (tl, Some(nl)) => {
-                        // Pick the smaller layout; otherwise,
-                        // pick the layout with the larger niche; otherwise,
-                        // pick tagged as it has simpler codegen.
-                        use Ordering::*;
-                        let niche_size = |tmp_l: &TmpLayout<'_>| {
-                            tmp_l.layout.largest_niche.map_or(0, |n| n.available(dl))
-                        };
-                        match (
-                            tl.layout.size.cmp(&nl.layout.size),
-                            niche_size(&tl).cmp(&niche_size(&nl)),
-                        ) {
-                            (Greater, _) => nl,
-                            (Equal, Less) => nl,
-                            _ => tl,
-                        }
-                    }
-                    (tl, None) => tl,
-                };
-
-                // Now we can intern the variant layouts and store them in the enum layout.
-                best_layout.layout.variants = match best_layout.layout.variants {
-                    Variants::Multiple { tag, tag_encoding, tag_field, .. } => Variants::Multiple {
-                        tag,
-                        tag_encoding,
-                        tag_field,
-                        variants: best_layout
-                            .variants
-                            .into_iter()
-                            .map(|layout| tcx.intern_layout(layout))
-                            .collect(),
-                    },
-                    _ => bug!(),
-                };
-
-                tcx.intern_layout(best_layout.layout)
-            }
-
-            // Types with no meaningful known layout.
-            ty::Projection(_) | ty::Opaque(..) => {
-                // NOTE(eddyb) `layout_of` query should've normalized these away,
-                // if that was possible, so there's no reason to try again here.
-                return Err(LayoutError::Unknown(ty));
-            }
-
-            ty::Placeholder(..) | ty::GeneratorWitness(..) | ty::Infer(_) => {
-                bug!("Layout::compute: unexpected type `{}`", ty)
-            }
-
-            ty::Bound(..) | ty::Param(_) | ty::Error(_) => {
-                return Err(LayoutError::Unknown(ty));
-            }
-        })
-    }
-}
-
-/// Overlap eligibility and variant assignment for each GeneratorSavedLocal.
-#[derive(Clone, Debug, PartialEq)]
-enum SavedLocalEligibility {
-    Unassigned,
-    Assigned(VariantIdx),
-    // FIXME: Use newtype_index so we aren't wasting bytes
-    Ineligible(Option<u32>),
-}
-
-// When laying out generators, we divide our saved local fields into two
-// categories: overlap-eligible and overlap-ineligible.
-//
-// Those fields which are ineligible for overlap go in a "prefix" at the
-// beginning of the layout, and always have space reserved for them.
-//
-// Overlap-eligible fields are only assigned to one variant, so we lay
-// those fields out for each variant and put them right after the
-// prefix.
-//
-// Finally, in the layout details, we point to the fields from the
-// variants they are assigned to. It is possible for some fields to be
-// included in multiple variants. No field ever "moves around" in the
-// layout; its offset is always the same.
-//
-// Also included in the layout are the upvars and the discriminant.
-// These are included as fields on the "outer" layout; they are not part
-// of any variant.
-impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
-    /// Compute the eligibility and assignment of each local.
-    fn generator_saved_local_eligibility(
-        &self,
-        info: &GeneratorLayout<'tcx>,
-    ) -> (BitSet<GeneratorSavedLocal>, IndexVec<GeneratorSavedLocal, SavedLocalEligibility>) {
-        use SavedLocalEligibility::*;
-
-        let mut assignments: IndexVec<GeneratorSavedLocal, SavedLocalEligibility> =
-            IndexVec::from_elem_n(Unassigned, info.field_tys.len());
-
-        // The saved locals not eligible for overlap. These will get
-        // "promoted" to the prefix of our generator.
-        let mut ineligible_locals = BitSet::new_empty(info.field_tys.len());
-
-        // Figure out which of our saved locals are fields in only
-        // one variant. The rest are deemed ineligible for overlap.
-        for (variant_index, fields) in info.variant_fields.iter_enumerated() {
-            for local in fields {
-                match assignments[*local] {
-                    Unassigned => {
-                        assignments[*local] = Assigned(variant_index);
-                    }
-                    Assigned(idx) => {
-                        // We've already seen this local at another suspension
-                        // point, so it is no longer a candidate.
-                        trace!(
-                            "removing local {:?} in >1 variant ({:?}, {:?})",
-                            local,
-                            variant_index,
-                            idx
-                        );
-                        ineligible_locals.insert(*local);
-                        assignments[*local] = Ineligible(None);
-                    }
-                    Ineligible(_) => {}
-                }
-            }
-        }
-
-        // Next, check every pair of eligible locals to see if they
-        // conflict.
-        for local_a in info.storage_conflicts.rows() {
-            let conflicts_a = info.storage_conflicts.count(local_a);
-            if ineligible_locals.contains(local_a) {
-                continue;
-            }
-
-            for local_b in info.storage_conflicts.iter(local_a) {
-                // local_a and local_b are storage live at the same time, therefore they
-                // cannot overlap in the generator layout. The only way to guarantee
-                // this is if they are in the same variant, or one is ineligible
-                // (which means it is stored in every variant).
-                if ineligible_locals.contains(local_b)
-                    || assignments[local_a] == assignments[local_b]
-                {
-                    continue;
-                }
-
-                // If they conflict, we will choose one to make ineligible.
-                // This is not always optimal; it's just a greedy heuristic that
-                // seems to produce good results most of the time.
-                let conflicts_b = info.storage_conflicts.count(local_b);
-                let (remove, other) =
-                    if conflicts_a > conflicts_b { (local_a, local_b) } else { (local_b, local_a) };
-                ineligible_locals.insert(remove);
-                assignments[remove] = Ineligible(None);
-                trace!("removing local {:?} due to conflict with {:?}", remove, other);
-            }
-        }
-
-        // Count the number of variants in use. If only one of them, then it is
-        // impossible to overlap any locals in our layout. In this case it's
-        // always better to make the remaining locals ineligible, so we can
-        // lay them out with the other locals in the prefix and eliminate
-        // unnecessary padding bytes.
-        {
-            let mut used_variants = BitSet::new_empty(info.variant_fields.len());
-            for assignment in &assignments {
-                if let Assigned(idx) = assignment {
-                    used_variants.insert(*idx);
-                }
-            }
-            if used_variants.count() < 2 {
-                for assignment in assignments.iter_mut() {
-                    *assignment = Ineligible(None);
-                }
-                ineligible_locals.insert_all();
-            }
-        }
-
-        // Write down the order of our locals that will be promoted to the prefix.
-        {
-            for (idx, local) in ineligible_locals.iter().enumerate() {
-                assignments[local] = Ineligible(Some(idx as u32));
-            }
-        }
-        debug!("generator saved local assignments: {:?}", assignments);
-
-        (ineligible_locals, assignments)
-    }
-
-    /// Compute the full generator layout.
-    fn generator_layout(
-        &self,
-        ty: Ty<'tcx>,
-        def_id: hir::def_id::DefId,
-        substs: SubstsRef<'tcx>,
-    ) -> Result<Layout<'tcx>, LayoutError<'tcx>> {
-        use SavedLocalEligibility::*;
-        let tcx = self.tcx;
-        let subst_field = |ty: Ty<'tcx>| EarlyBinder(ty).subst(tcx, substs);
-
-        let Some(info) = tcx.generator_layout(def_id) else {
-            return Err(LayoutError::Unknown(ty));
-        };
-        let (ineligible_locals, assignments) = self.generator_saved_local_eligibility(&info);
-
-        // Build a prefix layout, including "promoting" all ineligible
-        // locals as part of the prefix. We compute the layout of all of
-        // these fields at once to get optimal packing.
-        let tag_index = substs.as_generator().prefix_tys().count();
-
-        // `info.variant_fields` already accounts for the reserved variants, so no need to add them.
-        let max_discr = (info.variant_fields.len() - 1) as u128;
-        let discr_int = Integer::fit_unsigned(max_discr);
-        let discr_int_ty = discr_int.to_ty(tcx, false);
-        let tag = Scalar::Initialized {
-            value: Primitive::Int(discr_int, false),
-            valid_range: WrappingRange { start: 0, end: max_discr },
-        };
-        let tag_layout = self.tcx.intern_layout(LayoutS::scalar(self, tag));
-        let tag_layout = TyAndLayout { ty: discr_int_ty, layout: tag_layout };
-
-        let promoted_layouts = ineligible_locals
-            .iter()
-            .map(|local| subst_field(info.field_tys[local]))
-            .map(|ty| tcx.mk_maybe_uninit(ty))
-            .map(|ty| self.layout_of(ty));
-        let prefix_layouts = substs
-            .as_generator()
-            .prefix_tys()
-            .map(|ty| self.layout_of(ty))
-            .chain(iter::once(Ok(tag_layout)))
-            .chain(promoted_layouts)
-            .collect::<Result<Vec<_>, _>>()?;
-        let prefix = self.univariant_uninterned(
-            ty,
-            &prefix_layouts,
-            &ReprOptions::default(),
-            StructKind::AlwaysSized,
-        )?;
-
-        let (prefix_size, prefix_align) = (prefix.size, prefix.align);
-
-        // Split the prefix layout into the "outer" fields (upvars and
-        // discriminant) and the "promoted" fields. Promoted fields will
-        // get included in each variant that requested them in
-        // GeneratorLayout.
-        debug!("prefix = {:#?}", prefix);
-        let (outer_fields, promoted_offsets, promoted_memory_index) = match prefix.fields {
-            FieldsShape::Arbitrary { mut offsets, memory_index } => {
-                let mut inverse_memory_index = invert_mapping(&memory_index);
-
-                // "a" (`0..b_start`) and "b" (`b_start..`) correspond to
-                // "outer" and "promoted" fields respectively.
-                let b_start = (tag_index + 1) as u32;
-                let offsets_b = offsets.split_off(b_start as usize);
-                let offsets_a = offsets;
-
-                // Disentangle the "a" and "b" components of `inverse_memory_index`
-                // by preserving the order but keeping only one disjoint "half" each.
-                // FIXME(eddyb) build a better abstraction for permutations, if possible.
-                let inverse_memory_index_b: Vec<_> =
-                    inverse_memory_index.iter().filter_map(|&i| i.checked_sub(b_start)).collect();
-                inverse_memory_index.retain(|&i| i < b_start);
-                let inverse_memory_index_a = inverse_memory_index;
-
-                // Since `inverse_memory_index_{a,b}` each only refer to their
-                // respective fields, they can be safely inverted
-                let memory_index_a = invert_mapping(&inverse_memory_index_a);
-                let memory_index_b = invert_mapping(&inverse_memory_index_b);
-
-                let outer_fields =
-                    FieldsShape::Arbitrary { offsets: offsets_a, memory_index: memory_index_a };
-                (outer_fields, offsets_b, memory_index_b)
-            }
-            _ => bug!(),
-        };
-
-        let mut size = prefix.size;
-        let mut align = prefix.align;
-        let variants = info
-            .variant_fields
-            .iter_enumerated()
-            .map(|(index, variant_fields)| {
-                // Only include overlap-eligible fields when we compute our variant layout.
-                let variant_only_tys = variant_fields
-                    .iter()
-                    .filter(|local| match assignments[**local] {
-                        Unassigned => bug!(),
-                        Assigned(v) if v == index => true,
-                        Assigned(_) => bug!("assignment does not match variant"),
-                        Ineligible(_) => false,
-                    })
-                    .map(|local| subst_field(info.field_tys[*local]));
-
-                let mut variant = self.univariant_uninterned(
-                    ty,
-                    &variant_only_tys
-                        .map(|ty| self.layout_of(ty))
-                        .collect::<Result<Vec<_>, _>>()?,
-                    &ReprOptions::default(),
-                    StructKind::Prefixed(prefix_size, prefix_align.abi),
-                )?;
-                variant.variants = Variants::Single { index };
-
-                let FieldsShape::Arbitrary { offsets, memory_index } = variant.fields else {
-                    bug!();
-                };
-
-                // Now, stitch the promoted and variant-only fields back together in
-                // the order they are mentioned by our GeneratorLayout.
-                // Because we only use some subset (that can differ between variants)
-                // of the promoted fields, we can't just pick those elements of the
-                // `promoted_memory_index` (as we'd end up with gaps).
-                // So instead, we build an "inverse memory_index", as if all of the
-                // promoted fields were being used, but leave the elements not in the
-                // subset as `INVALID_FIELD_IDX`, which we can filter out later to
-                // obtain a valid (bijective) mapping.
-                const INVALID_FIELD_IDX: u32 = !0;
-                let mut combined_inverse_memory_index =
-                    vec![INVALID_FIELD_IDX; promoted_memory_index.len() + memory_index.len()];
-                let mut offsets_and_memory_index = iter::zip(offsets, memory_index);
-                let combined_offsets = variant_fields
-                    .iter()
-                    .enumerate()
-                    .map(|(i, local)| {
-                        let (offset, memory_index) = match assignments[*local] {
-                            Unassigned => bug!(),
-                            Assigned(_) => {
-                                let (offset, memory_index) =
-                                    offsets_and_memory_index.next().unwrap();
-                                (offset, promoted_memory_index.len() as u32 + memory_index)
-                            }
-                            Ineligible(field_idx) => {
-                                let field_idx = field_idx.unwrap() as usize;
-                                (promoted_offsets[field_idx], promoted_memory_index[field_idx])
-                            }
-                        };
-                        combined_inverse_memory_index[memory_index as usize] = i as u32;
-                        offset
-                    })
-                    .collect();
-
-                // Remove the unused slots and invert the mapping to obtain the
-                // combined `memory_index` (also see previous comment).
-                combined_inverse_memory_index.retain(|&i| i != INVALID_FIELD_IDX);
-                let combined_memory_index = invert_mapping(&combined_inverse_memory_index);
-
-                variant.fields = FieldsShape::Arbitrary {
-                    offsets: combined_offsets,
-                    memory_index: combined_memory_index,
-                };
-
-                size = size.max(variant.size);
-                align = align.max(variant.align);
-                Ok(tcx.intern_layout(variant))
-            })
-            .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
-
-        size = size.align_to(align.abi);
-
-        let abi =
-            if prefix.abi.is_uninhabited() || variants.iter().all(|v| v.abi().is_uninhabited()) {
-                Abi::Uninhabited
-            } else {
-                Abi::Aggregate { sized: true }
-            };
-
-        let layout = tcx.intern_layout(LayoutS {
-            variants: Variants::Multiple {
-                tag,
-                tag_encoding: TagEncoding::Direct,
-                tag_field: tag_index,
-                variants,
-            },
-            fields: outer_fields,
-            abi,
-            largest_niche: prefix.largest_niche,
-            size,
-            align,
-        });
-        debug!("generator layout ({:?}): {:#?}", ty, layout);
-        Ok(layout)
-    }
-
-    /// This is invoked by the `layout_of` query to record the final
-    /// layout of each type.
-    #[inline(always)]
-    fn record_layout_for_printing(&self, layout: TyAndLayout<'tcx>) {
-        // If we are running with `-Zprint-type-sizes`, maybe record layouts
-        // for dumping later.
-        if self.tcx.sess.opts.unstable_opts.print_type_sizes {
-            self.record_layout_for_printing_outlined(layout)
-        }
-    }
-
-    fn record_layout_for_printing_outlined(&self, layout: TyAndLayout<'tcx>) {
-        // Ignore layouts that are done with non-empty environments or
-        // non-monomorphic layouts, as the user only wants to see the stuff
-        // resulting from the final codegen session.
-        if layout.ty.has_param_types_or_consts() || !self.param_env.caller_bounds().is_empty() {
-            return;
-        }
-
-        // (delay format until we actually need it)
-        let record = |kind, packed, opt_discr_size, variants| {
-            let type_desc = format!("{:?}", layout.ty);
-            self.tcx.sess.code_stats.record_type_size(
-                kind,
-                type_desc,
-                layout.align.abi,
-                layout.size,
-                packed,
-                opt_discr_size,
-                variants,
-            );
-        };
-
-        let adt_def = match *layout.ty.kind() {
-            ty::Adt(ref adt_def, _) => {
-                debug!("print-type-size t: `{:?}` process adt", layout.ty);
-                adt_def
-            }
-
-            ty::Closure(..) => {
-                debug!("print-type-size t: `{:?}` record closure", layout.ty);
-                record(DataTypeKind::Closure, false, None, vec![]);
-                return;
-            }
-
-            _ => {
-                debug!("print-type-size t: `{:?}` skip non-nominal", layout.ty);
-                return;
-            }
-        };
-
-        let adt_kind = adt_def.adt_kind();
-        let adt_packed = adt_def.repr().pack.is_some();
-
-        let build_variant_info = |n: Option<Symbol>, flds: &[Symbol], layout: TyAndLayout<'tcx>| {
-            let mut min_size = Size::ZERO;
-            let field_info: Vec<_> = flds
-                .iter()
-                .enumerate()
-                .map(|(i, &name)| {
-                    let field_layout = layout.field(self, i);
-                    let offset = layout.fields.offset(i);
-                    let field_end = offset + field_layout.size;
-                    if min_size < field_end {
-                        min_size = field_end;
-                    }
-                    FieldInfo {
-                        name,
-                        offset: offset.bytes(),
-                        size: field_layout.size.bytes(),
-                        align: field_layout.align.abi.bytes(),
-                    }
-                })
-                .collect();
-
-            VariantInfo {
-                name: n,
-                kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact },
-                align: layout.align.abi.bytes(),
-                size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() },
-                fields: field_info,
-            }
-        };
-
-        match layout.variants {
-            Variants::Single { index } => {
-                if !adt_def.variants().is_empty() && layout.fields != FieldsShape::Primitive {
-                    debug!(
-                        "print-type-size `{:#?}` variant {}",
-                        layout,
-                        adt_def.variant(index).name
-                    );
-                    let variant_def = &adt_def.variant(index);
-                    let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect();
-                    record(
-                        adt_kind.into(),
-                        adt_packed,
-                        None,
-                        vec![build_variant_info(Some(variant_def.name), &fields, layout)],
-                    );
-                } else {
-                    // (This case arises for *empty* enums; so give it
-                    // zero variants.)
-                    record(adt_kind.into(), adt_packed, None, vec![]);
-                }
-            }
-
-            Variants::Multiple { tag, ref tag_encoding, .. } => {
-                debug!(
-                    "print-type-size `{:#?}` adt general variants def {}",
-                    layout.ty,
-                    adt_def.variants().len()
-                );
-                let variant_infos: Vec<_> = adt_def
-                    .variants()
-                    .iter_enumerated()
-                    .map(|(i, variant_def)| {
-                        let fields: Vec<_> = variant_def.fields.iter().map(|f| f.name).collect();
-                        build_variant_info(
-                            Some(variant_def.name),
-                            &fields,
-                            layout.for_variant(self, i),
-                        )
-                    })
-                    .collect();
-                record(
-                    adt_kind.into(),
-                    adt_packed,
-                    match tag_encoding {
-                        TagEncoding::Direct => Some(tag.size(self)),
-                        _ => None,
-                    },
-                    variant_infos,
-                );
-            }
-        }
-    }
-}
-
 /// Type size "skeleton", i.e., the only information determining a type's size.
 /// While this is conservative, (aside from constant sizes, only pointers,
 /// newtypes thereof and null pointer optimized enums are allowed), it is
@@ -2058,7 +263,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
         tcx: TyCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> Result<SizeSkeleton<'tcx>, LayoutError<'tcx>> {
-        debug_assert!(!ty.has_infer_types_or_consts());
+        debug_assert!(!ty.has_non_region_infer());
 
         // First try computing a static layout.
         let err = match tcx.layout_of(param_env.and(ty)) {
@@ -2074,7 +279,7 @@ impl<'tcx> SizeSkeleton<'tcx> {
                 let tail = tcx.struct_tail_erasing_lifetimes(pointee, param_env);
                 match tail.kind() {
                     ty::Param(_) | ty::Projection(_) => {
-                        debug_assert!(tail.has_param_types_or_consts());
+                        debug_assert!(tail.has_non_region_param());
                         Ok(SizeSkeleton::Pointer { non_zero, tail: tcx.erase_regions(tail) })
                     }
                     _ => bug!(
@@ -2625,7 +830,7 @@ where
                 } else {
                     match mt {
                         hir::Mutability::Not => {
-                            if ty.is_freeze(tcx.at(DUMMY_SP), cx.param_env()) {
+                            if ty.is_freeze(tcx, cx.param_env()) {
                                 PointerKind::Frozen
                             } else {
                                 PointerKind::SharedMutable
@@ -2636,7 +841,7 @@ where
                             // noalias, as another pointer to the structure can be obtained, that
                             // is not based-on the original reference. We consider all !Unpin
                             // types to be potentially self-referential here.
-                            if ty.is_unpin(tcx.at(DUMMY_SP), cx.param_env()) {
+                            if ty.is_unpin(tcx, cx.param_env()) {
                                 PointerKind::UniqueBorrowed
                             } else {
                                 PointerKind::UniqueBorrowedPinned
@@ -2748,112 +953,6 @@ where
     }
 }
 
-impl<'tcx> ty::Instance<'tcx> {
-    // NOTE(eddyb) this is private to avoid using it from outside of
-    // `fn_abi_of_instance` - any other uses are either too high-level
-    // for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
-    // or should go through `FnAbi` instead, to avoid losing any
-    // adjustments `fn_abi_of_instance` might be performing.
-    #[tracing::instrument(level = "debug", skip(tcx, param_env))]
-    fn fn_sig_for_fn_abi(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> ty::PolyFnSig<'tcx> {
-        let ty = self.ty(tcx, param_env);
-        match *ty.kind() {
-            ty::FnDef(..) => {
-                // HACK(davidtwco,eddyb): This is a workaround for polymorphization considering
-                // parameters unused if they show up in the signature, but not in the `mir::Body`
-                // (i.e. due to being inside a projection that got normalized, see
-                // `src/test/ui/polymorphization/normalized_sig_types.rs`), and codegen not keeping
-                // track of a polymorphization `ParamEnv` to allow normalizing later.
-                let mut sig = match *ty.kind() {
-                    ty::FnDef(def_id, substs) => tcx
-                        .normalize_erasing_regions(tcx.param_env(def_id), tcx.bound_fn_sig(def_id))
-                        .subst(tcx, substs),
-                    _ => unreachable!(),
-                };
-
-                if let ty::InstanceDef::VTableShim(..) = self.def {
-                    // Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`.
-                    sig = sig.map_bound(|mut sig| {
-                        let mut inputs_and_output = sig.inputs_and_output.to_vec();
-                        inputs_and_output[0] = tcx.mk_mut_ptr(inputs_and_output[0]);
-                        sig.inputs_and_output = tcx.intern_type_list(&inputs_and_output);
-                        sig
-                    });
-                }
-                sig
-            }
-            ty::Closure(def_id, substs) => {
-                let sig = substs.as_closure().sig();
-
-                let bound_vars = tcx.mk_bound_variable_kinds(
-                    sig.bound_vars()
-                        .iter()
-                        .chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
-                );
-                let br = ty::BoundRegion {
-                    var: ty::BoundVar::from_usize(bound_vars.len() - 1),
-                    kind: ty::BoundRegionKind::BrEnv,
-                };
-                let env_region = ty::ReLateBound(ty::INNERMOST, br);
-                let env_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
-
-                let sig = sig.skip_binder();
-                ty::Binder::bind_with_vars(
-                    tcx.mk_fn_sig(
-                        iter::once(env_ty).chain(sig.inputs().iter().cloned()),
-                        sig.output(),
-                        sig.c_variadic,
-                        sig.unsafety,
-                        sig.abi,
-                    ),
-                    bound_vars,
-                )
-            }
-            ty::Generator(_, substs, _) => {
-                let sig = substs.as_generator().poly_sig();
-
-                let bound_vars = tcx.mk_bound_variable_kinds(
-                    sig.bound_vars()
-                        .iter()
-                        .chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
-                );
-                let br = ty::BoundRegion {
-                    var: ty::BoundVar::from_usize(bound_vars.len() - 1),
-                    kind: ty::BoundRegionKind::BrEnv,
-                };
-                let env_region = ty::ReLateBound(ty::INNERMOST, br);
-                let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
-
-                let pin_did = tcx.require_lang_item(LangItem::Pin, None);
-                let pin_adt_ref = tcx.adt_def(pin_did);
-                let pin_substs = tcx.intern_substs(&[env_ty.into()]);
-                let env_ty = tcx.mk_adt(pin_adt_ref, pin_substs);
-
-                let sig = sig.skip_binder();
-                let state_did = tcx.require_lang_item(LangItem::GeneratorState, None);
-                let state_adt_ref = tcx.adt_def(state_did);
-                let state_substs = tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]);
-                let ret_ty = tcx.mk_adt(state_adt_ref, state_substs);
-                ty::Binder::bind_with_vars(
-                    tcx.mk_fn_sig(
-                        [env_ty, sig.resume_ty].iter(),
-                        &ret_ty,
-                        false,
-                        hir::Unsafety::Normal,
-                        rustc_target::spec::abi::Abi::Rust,
-                    ),
-                    bound_vars,
-                )
-            }
-            _ => bug!("unexpected type {:?} in Instance::fn_sig", ty),
-        }
-    }
-}
-
 /// Calculates whether a function's ABI can unwind or not.
 ///
 /// This takes two primary parameters:
@@ -2996,40 +1095,6 @@ pub fn fn_can_unwind<'tcx>(tcx: TyCtxt<'tcx>, fn_def_id: Option<DefId>, abi: Spe
     }
 }
 
-#[inline]
-pub fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
-    use rustc_target::spec::abi::Abi::*;
-    match tcx.sess.target.adjust_abi(abi) {
-        RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust,
-        RustCold => Conv::RustCold,
-
-        // It's the ABI's job to select this, not ours.
-        System { .. } => bug!("system abi should be selected elsewhere"),
-        EfiApi => bug!("eficall abi should be selected elsewhere"),
-
-        Stdcall { .. } => Conv::X86Stdcall,
-        Fastcall { .. } => Conv::X86Fastcall,
-        Vectorcall { .. } => Conv::X86VectorCall,
-        Thiscall { .. } => Conv::X86ThisCall,
-        C { .. } => Conv::C,
-        Unadjusted => Conv::C,
-        Win64 { .. } => Conv::X86_64Win64,
-        SysV64 { .. } => Conv::X86_64SysV,
-        Aapcs { .. } => Conv::ArmAapcs,
-        CCmseNonSecureCall => Conv::CCmseNonSecureCall,
-        PtxKernel => Conv::PtxKernel,
-        Msp430Interrupt => Conv::Msp430Intr,
-        X86Interrupt => Conv::X86Intr,
-        AmdGpuKernel => Conv::AmdGpuKernel,
-        AvrInterrupt => Conv::AvrInterrupt,
-        AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
-        Wasm => Conv::C,
-
-        // These API constants ought to be more specific...
-        Cdecl { .. } => Conv::C,
-    }
-}
-
 /// Error produced by attempting to compute or adjust a `FnAbi`.
 #[derive(Copy, Clone, Debug, HashStable)]
 pub enum FnAbiError<'tcx> {
@@ -3061,6 +1126,12 @@ impl<'tcx> fmt::Display for FnAbiError<'tcx> {
     }
 }
 
+impl<'tcx> IntoDiagnostic<'tcx, !> for FnAbiError<'tcx> {
+    fn into_diagnostic(self, handler: &'tcx Handler) -> DiagnosticBuilder<'tcx, !> {
+        handler.struct_fatal(self.to_string())
+    }
+}
+
 // FIXME(eddyb) maybe use something like this for an unified `fn_abi_of`, not
 // just for error handling.
 #[derive(Debug)]
@@ -3142,367 +1213,3 @@ pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> {
 }
 
 impl<'tcx, C: FnAbiOfHelpers<'tcx>> FnAbiOf<'tcx> for C {}
-
-fn fn_abi_of_fn_ptr<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    query: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
-) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
-    let (param_env, (sig, extra_args)) = query.into_parts();
-
-    LayoutCx { tcx, param_env }.fn_abi_new_uncached(sig, extra_args, None, None, false)
-}
-
-fn fn_abi_of_instance<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    query: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
-) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
-    let (param_env, (instance, extra_args)) = query.into_parts();
-
-    let sig = instance.fn_sig_for_fn_abi(tcx, param_env);
-
-    let caller_location = if instance.def.requires_caller_location(tcx) {
-        Some(tcx.caller_location_ty())
-    } else {
-        None
-    };
-
-    LayoutCx { tcx, param_env }.fn_abi_new_uncached(
-        sig,
-        extra_args,
-        caller_location,
-        Some(instance.def_id()),
-        matches!(instance.def, ty::InstanceDef::Virtual(..)),
-    )
-}
-
-// Handle safe Rust thin and fat pointers.
-pub fn adjust_for_rust_scalar<'tcx>(
-    cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
-    attrs: &mut ArgAttributes,
-    scalar: Scalar,
-    layout: TyAndLayout<'tcx>,
-    offset: Size,
-    is_return: bool,
-) {
-    // Booleans are always a noundef i1 that needs to be zero-extended.
-    if scalar.is_bool() {
-        attrs.ext(ArgExtension::Zext);
-        attrs.set(ArgAttribute::NoUndef);
-        return;
-    }
-
-    // Scalars which have invalid values cannot be undef.
-    if !scalar.is_always_valid(&cx) {
-        attrs.set(ArgAttribute::NoUndef);
-    }
-
-    // Only pointer types handled below.
-    let Scalar::Initialized { value: Pointer, valid_range} = scalar else { return };
-
-    if !valid_range.contains(0) {
-        attrs.set(ArgAttribute::NonNull);
-    }
-
-    if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
-        if let Some(kind) = pointee.safe {
-            attrs.pointee_align = Some(pointee.align);
-
-            // `Box` (`UniqueBorrowed`) are not necessarily dereferenceable
-            // for the entire duration of the function as they can be deallocated
-            // at any time. Same for shared mutable references. If LLVM had a
-            // way to say "dereferenceable on entry" we could use it here.
-            attrs.pointee_size = match kind {
-                PointerKind::UniqueBorrowed
-                | PointerKind::UniqueBorrowedPinned
-                | PointerKind::Frozen => pointee.size,
-                PointerKind::SharedMutable | PointerKind::UniqueOwned => Size::ZERO,
-            };
-
-            // `Box`, `&T`, and `&mut T` cannot be undef.
-            // Note that this only applies to the value of the pointer itself;
-            // this attribute doesn't make it UB for the pointed-to data to be undef.
-            attrs.set(ArgAttribute::NoUndef);
-
-            // The aliasing rules for `Box<T>` are still not decided, but currently we emit
-            // `noalias` for it. This can be turned off using an unstable flag.
-            // See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
-            let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias.unwrap_or(true);
-
-            // `&mut` pointer parameters never alias other parameters,
-            // or mutable global data
-            //
-            // `&T` where `T` contains no `UnsafeCell<U>` is immutable,
-            // and can be marked as both `readonly` and `noalias`, as
-            // LLVM's definition of `noalias` is based solely on memory
-            // dependencies rather than pointer equality
-            //
-            // Due to past miscompiles in LLVM, we apply a separate NoAliasMutRef attribute
-            // for UniqueBorrowed arguments, so that the codegen backend can decide whether
-            // or not to actually emit the attribute. It can also be controlled with the
-            // `-Zmutable-noalias` debugging option.
-            let no_alias = match kind {
-                PointerKind::SharedMutable
-                | PointerKind::UniqueBorrowed
-                | PointerKind::UniqueBorrowedPinned => false,
-                PointerKind::UniqueOwned => noalias_for_box,
-                PointerKind::Frozen => !is_return,
-            };
-            if no_alias {
-                attrs.set(ArgAttribute::NoAlias);
-            }
-
-            if kind == PointerKind::Frozen && !is_return {
-                attrs.set(ArgAttribute::ReadOnly);
-            }
-
-            if kind == PointerKind::UniqueBorrowed && !is_return {
-                attrs.set(ArgAttribute::NoAliasMutRef);
-            }
-        }
-    }
-}
-
-impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
-    // FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
-    // arguments of this method, into a separate `struct`.
-    #[tracing::instrument(
-        level = "debug",
-        skip(self, caller_location, fn_def_id, force_thin_self_ptr)
-    )]
-    fn fn_abi_new_uncached(
-        &self,
-        sig: ty::PolyFnSig<'tcx>,
-        extra_args: &[Ty<'tcx>],
-        caller_location: Option<Ty<'tcx>>,
-        fn_def_id: Option<DefId>,
-        // FIXME(eddyb) replace this with something typed, like an `enum`.
-        force_thin_self_ptr: bool,
-    ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
-        let sig = self.tcx.normalize_erasing_late_bound_regions(self.param_env, sig);
-
-        let conv = conv_from_spec_abi(self.tcx(), sig.abi);
-
-        let mut inputs = sig.inputs();
-        let extra_args = if sig.abi == RustCall {
-            assert!(!sig.c_variadic && extra_args.is_empty());
-
-            if let Some(input) = sig.inputs().last() {
-                if let ty::Tuple(tupled_arguments) = input.kind() {
-                    inputs = &sig.inputs()[0..sig.inputs().len() - 1];
-                    tupled_arguments
-                } else {
-                    bug!(
-                        "argument to function with \"rust-call\" ABI \
-                            is not a tuple"
-                    );
-                }
-            } else {
-                bug!(
-                    "argument to function with \"rust-call\" ABI \
-                        is not a tuple"
-                );
-            }
-        } else {
-            assert!(sig.c_variadic || extra_args.is_empty());
-            extra_args
-        };
-
-        let target = &self.tcx.sess.target;
-        let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl" | "uclibc");
-        let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
-        let linux_s390x_gnu_like =
-            target.os == "linux" && target.arch == "s390x" && target_env_gnu_like;
-        let linux_sparc64_gnu_like =
-            target.os == "linux" && target.arch == "sparc64" && target_env_gnu_like;
-        let linux_powerpc_gnu_like =
-            target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
-        use SpecAbi::*;
-        let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
-
-        let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
-            let span = tracing::debug_span!("arg_of");
-            let _entered = span.enter();
-            let is_return = arg_idx.is_none();
-
-            let layout = self.layout_of(ty)?;
-            let layout = if force_thin_self_ptr && arg_idx == Some(0) {
-                // Don't pass the vtable, it's not an argument of the virtual fn.
-                // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
-                // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
-                make_thin_self_ptr(self, layout)
-            } else {
-                layout
-            };
-
-            let mut arg = ArgAbi::new(self, layout, |layout, scalar, offset| {
-                let mut attrs = ArgAttributes::new();
-                adjust_for_rust_scalar(*self, &mut attrs, scalar, *layout, offset, is_return);
-                attrs
-            });
-
-            if arg.layout.is_zst() {
-                // For some forsaken reason, x86_64-pc-windows-gnu
-                // doesn't ignore zero-sized struct arguments.
-                // The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl,uclibc}.
-                if is_return
-                    || rust_abi
-                    || (!win_x64_gnu
-                        && !linux_s390x_gnu_like
-                        && !linux_sparc64_gnu_like
-                        && !linux_powerpc_gnu_like)
-                {
-                    arg.mode = PassMode::Ignore;
-                }
-            }
-
-            Ok(arg)
-        };
-
-        let mut fn_abi = FnAbi {
-            ret: arg_of(sig.output(), None)?,
-            args: inputs
-                .iter()
-                .copied()
-                .chain(extra_args.iter().copied())
-                .chain(caller_location)
-                .enumerate()
-                .map(|(i, ty)| arg_of(ty, Some(i)))
-                .collect::<Result<_, _>>()?,
-            c_variadic: sig.c_variadic,
-            fixed_count: inputs.len() as u32,
-            conv,
-            can_unwind: fn_can_unwind(self.tcx(), fn_def_id, sig.abi),
-        };
-        self.fn_abi_adjust_for_abi(&mut fn_abi, sig.abi)?;
-        debug!("fn_abi_new_uncached = {:?}", fn_abi);
-        Ok(self.tcx.arena.alloc(fn_abi))
-    }
-
-    #[tracing::instrument(level = "trace", skip(self))]
-    fn fn_abi_adjust_for_abi(
-        &self,
-        fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
-        abi: SpecAbi,
-    ) -> Result<(), FnAbiError<'tcx>> {
-        if abi == SpecAbi::Unadjusted {
-            return Ok(());
-        }
-
-        if abi == SpecAbi::Rust
-            || abi == SpecAbi::RustCall
-            || abi == SpecAbi::RustIntrinsic
-            || abi == SpecAbi::PlatformIntrinsic
-        {
-            let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>| {
-                if arg.is_ignore() {
-                    return;
-                }
-
-                match arg.layout.abi {
-                    Abi::Aggregate { .. } => {}
-
-                    // This is a fun case! The gist of what this is doing is
-                    // that we want callers and callees to always agree on the
-                    // ABI of how they pass SIMD arguments. If we were to *not*
-                    // make these arguments indirect then they'd be immediates
-                    // in LLVM, which means that they'd used whatever the
-                    // appropriate ABI is for the callee and the caller. That
-                    // means, for example, if the caller doesn't have AVX
-                    // enabled but the callee does, then passing an AVX argument
-                    // across this boundary would cause corrupt data to show up.
-                    //
-                    // This problem is fixed by unconditionally passing SIMD
-                    // arguments through memory between callers and callees
-                    // which should get them all to agree on ABI regardless of
-                    // target feature sets. Some more information about this
-                    // issue can be found in #44367.
-                    //
-                    // Note that the platform intrinsic ABI is exempt here as
-                    // that's how we connect up to LLVM and it's unstable
-                    // anyway, we control all calls to it in libstd.
-                    Abi::Vector { .. }
-                        if abi != SpecAbi::PlatformIntrinsic
-                            && self.tcx.sess.target.simd_types_indirect =>
-                    {
-                        arg.make_indirect();
-                        return;
-                    }
-
-                    _ => return,
-                }
-
-                let size = arg.layout.size;
-                if arg.layout.is_unsized() || size > Pointer.size(self) {
-                    arg.make_indirect();
-                } else {
-                    // We want to pass small aggregates as immediates, but using
-                    // a LLVM aggregate type for this leads to bad optimizations,
-                    // so we pick an appropriately sized integer type instead.
-                    arg.cast_to(Reg { kind: RegKind::Integer, size });
-                }
-            };
-            fixup(&mut fn_abi.ret);
-            for arg in fn_abi.args.iter_mut() {
-                fixup(arg);
-            }
-        } else {
-            fn_abi.adjust_for_foreign_abi(self, abi)?;
-        }
-
-        Ok(())
-    }
-}
-
-#[tracing::instrument(level = "debug", skip(cx))]
-fn make_thin_self_ptr<'tcx>(
-    cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>),
-    layout: TyAndLayout<'tcx>,
-) -> TyAndLayout<'tcx> {
-    let tcx = cx.tcx();
-    let fat_pointer_ty = if layout.is_unsized() {
-        // unsized `self` is passed as a pointer to `self`
-        // FIXME (mikeyhew) change this to use &own if it is ever added to the language
-        tcx.mk_mut_ptr(layout.ty)
-    } else {
-        match layout.abi {
-            Abi::ScalarPair(..) | Abi::Scalar(..) => (),
-            _ => bug!("receiver type has unsupported layout: {:?}", layout),
-        }
-
-        // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
-        // with a Scalar (not ScalarPair) ABI. This is a hack that is understood
-        // elsewhere in the compiler as a method on a `dyn Trait`.
-        // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
-        // get a built-in pointer type
-        let mut fat_pointer_layout = layout;
-        'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
-            && !fat_pointer_layout.ty.is_region_ptr()
-        {
-            for i in 0..fat_pointer_layout.fields.count() {
-                let field_layout = fat_pointer_layout.field(cx, i);
-
-                if !field_layout.is_zst() {
-                    fat_pointer_layout = field_layout;
-                    continue 'descend_newtypes;
-                }
-            }
-
-            bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
-        }
-
-        fat_pointer_layout.ty
-    };
-
-    // we now have a type like `*mut RcBox<dyn Trait>`
-    // change its layout to that of `*mut ()`, a thin pointer, but keep the same type
-    // this is understood as a special case elsewhere in the compiler
-    let unit_ptr_ty = tcx.mk_mut_ptr(tcx.mk_unit());
-
-    TyAndLayout {
-        ty: fat_pointer_ty,
-
-        // NOTE(eddyb) using an empty `ParamEnv`, and `unwrap`-ing the `Result`
-        // should always work because the type is always `*mut ()`.
-        ..tcx.layout_of(ty::ParamEnv::reveal_all().and(unit_ptr_ty)).unwrap()
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/layout_sanity_check.rs b/compiler/rustc_middle/src/ty/layout_sanity_check.rs
deleted file mode 100644
index 87c85dcff..000000000
--- a/compiler/rustc_middle/src/ty/layout_sanity_check.rs
+++ /dev/null
@@ -1,303 +0,0 @@
-use crate::ty::{
-    layout::{LayoutCx, TyAndLayout},
-    TyCtxt,
-};
-use rustc_target::abi::*;
-
-use std::cmp;
-
-/// Enforce some basic invariants on layouts.
-pub(super) fn sanity_check_layout<'tcx>(
-    cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
-    layout: &TyAndLayout<'tcx>,
-) {
-    // Type-level uninhabitedness should always imply ABI uninhabitedness.
-    if cx.tcx.conservative_is_privately_uninhabited(cx.param_env.and(layout.ty)) {
-        assert!(layout.abi.is_uninhabited());
-    }
-
-    if layout.size.bytes() % layout.align.abi.bytes() != 0 {
-        bug!("size is not a multiple of align, in the following layout:\n{layout:#?}");
-    }
-
-    if cfg!(debug_assertions) {
-        /// Yields non-ZST fields of the type
-        fn non_zst_fields<'tcx, 'a>(
-            cx: &'a LayoutCx<'tcx, TyCtxt<'tcx>>,
-            layout: &'a TyAndLayout<'tcx>,
-        ) -> impl Iterator<Item = (Size, TyAndLayout<'tcx>)> + 'a {
-            (0..layout.layout.fields().count()).filter_map(|i| {
-                let field = layout.field(cx, i);
-                // Also checking `align == 1` here leads to test failures in
-                // `layout/zero-sized-array-union.rs`, where a type has a zero-size field with
-                // alignment 4 that still gets ignored during layout computation (which is okay
-                // since other fields already force alignment 4).
-                let zst = field.is_zst();
-                (!zst).then(|| (layout.fields.offset(i), field))
-            })
-        }
-
-        fn skip_newtypes<'tcx>(
-            cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
-            layout: &TyAndLayout<'tcx>,
-        ) -> TyAndLayout<'tcx> {
-            if matches!(layout.layout.variants(), Variants::Multiple { .. }) {
-                // Definitely not a newtype of anything.
-                return *layout;
-            }
-            let mut fields = non_zst_fields(cx, layout);
-            let Some(first) = fields.next() else {
-                // No fields here, so this could be a primitive or enum -- either way it's not a newtype around a thing
-                return *layout
-            };
-            if fields.next().is_none() {
-                let (offset, first) = first;
-                if offset == Size::ZERO && first.layout.size() == layout.size {
-                    // This is a newtype, so keep recursing.
-                    // FIXME(RalfJung): I don't think it would be correct to do any checks for
-                    // alignment here, so we don't. Is that correct?
-                    return skip_newtypes(cx, &first);
-                }
-            }
-            // No more newtypes here.
-            *layout
-        }
-
-        fn check_layout_abi<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: &TyAndLayout<'tcx>) {
-            match layout.layout.abi() {
-                Abi::Scalar(scalar) => {
-                    // No padding in scalars.
-                    let size = scalar.size(cx);
-                    let align = scalar.align(cx).abi;
-                    assert_eq!(
-                        layout.layout.size(),
-                        size,
-                        "size mismatch between ABI and layout in {layout:#?}"
-                    );
-                    assert_eq!(
-                        layout.layout.align().abi,
-                        align,
-                        "alignment mismatch between ABI and layout in {layout:#?}"
-                    );
-                    // Check that this matches the underlying field.
-                    let inner = skip_newtypes(cx, layout);
-                    assert!(
-                        matches!(inner.layout.abi(), Abi::Scalar(_)),
-                        "`Scalar` type {} is newtype around non-`Scalar` type {}",
-                        layout.ty,
-                        inner.ty
-                    );
-                    match inner.layout.fields() {
-                        FieldsShape::Primitive => {
-                            // Fine.
-                        }
-                        FieldsShape::Union(..) => {
-                            // FIXME: I guess we could also check something here? Like, look at all fields?
-                            return;
-                        }
-                        FieldsShape::Arbitrary { .. } => {
-                            // Should be an enum, the only field is the discriminant.
-                            assert!(
-                                inner.ty.is_enum(),
-                                "`Scalar` layout for non-primitive non-enum type {}",
-                                inner.ty
-                            );
-                            assert_eq!(
-                                inner.layout.fields().count(),
-                                1,
-                                "`Scalar` layout for multiple-field type in {inner:#?}",
-                            );
-                            let offset = inner.layout.fields().offset(0);
-                            let field = inner.field(cx, 0);
-                            // The field should be at the right offset, and match the `scalar` layout.
-                            assert_eq!(
-                                offset,
-                                Size::ZERO,
-                                "`Scalar` field at non-0 offset in {inner:#?}",
-                            );
-                            assert_eq!(
-                                field.size, size,
-                                "`Scalar` field with bad size in {inner:#?}",
-                            );
-                            assert_eq!(
-                                field.align.abi, align,
-                                "`Scalar` field with bad align in {inner:#?}",
-                            );
-                            assert!(
-                                matches!(field.abi, Abi::Scalar(_)),
-                                "`Scalar` field with bad ABI in {inner:#?}",
-                            );
-                        }
-                        _ => {
-                            panic!("`Scalar` layout for non-primitive non-enum type {}", inner.ty);
-                        }
-                    }
-                }
-                Abi::ScalarPair(scalar1, scalar2) => {
-                    // Sanity-check scalar pairs. These are a bit more flexible and support
-                    // padding, but we can at least ensure both fields actually fit into the layout
-                    // and the alignment requirement has not been weakened.
-                    let size1 = scalar1.size(cx);
-                    let align1 = scalar1.align(cx).abi;
-                    let size2 = scalar2.size(cx);
-                    let align2 = scalar2.align(cx).abi;
-                    assert!(
-                        layout.layout.align().abi >= cmp::max(align1, align2),
-                        "alignment mismatch between ABI and layout in {layout:#?}",
-                    );
-                    let field2_offset = size1.align_to(align2);
-                    assert!(
-                        layout.layout.size() >= field2_offset + size2,
-                        "size mismatch between ABI and layout in {layout:#?}"
-                    );
-                    // Check that the underlying pair of fields matches.
-                    let inner = skip_newtypes(cx, layout);
-                    assert!(
-                        matches!(inner.layout.abi(), Abi::ScalarPair(..)),
-                        "`ScalarPair` type {} is newtype around non-`ScalarPair` type {}",
-                        layout.ty,
-                        inner.ty
-                    );
-                    if matches!(inner.layout.variants(), Variants::Multiple { .. }) {
-                        // FIXME: ScalarPair for enums is enormously complicated and it is very hard
-                        // to check anything about them.
-                        return;
-                    }
-                    match inner.layout.fields() {
-                        FieldsShape::Arbitrary { .. } => {
-                            // Checked below.
-                        }
-                        FieldsShape::Union(..) => {
-                            // FIXME: I guess we could also check something here? Like, look at all fields?
-                            return;
-                        }
-                        _ => {
-                            panic!("`ScalarPair` layout with unexpected field shape in {inner:#?}");
-                        }
-                    }
-                    let mut fields = non_zst_fields(cx, &inner);
-                    let (offset1, field1) = fields.next().unwrap_or_else(|| {
-                        panic!("`ScalarPair` layout for type with not even one non-ZST field: {inner:#?}")
-                    });
-                    let (offset2, field2) = fields.next().unwrap_or_else(|| {
-                        panic!("`ScalarPair` layout for type with less than two non-ZST fields: {inner:#?}")
-                    });
-                    assert!(
-                        fields.next().is_none(),
-                        "`ScalarPair` layout for type with at least three non-ZST fields: {inner:#?}"
-                    );
-                    // The fields might be in opposite order.
-                    let (offset1, field1, offset2, field2) = if offset1 <= offset2 {
-                        (offset1, field1, offset2, field2)
-                    } else {
-                        (offset2, field2, offset1, field1)
-                    };
-                    // The fields should be at the right offset, and match the `scalar` layout.
-                    assert_eq!(
-                        offset1,
-                        Size::ZERO,
-                        "`ScalarPair` first field at non-0 offset in {inner:#?}",
-                    );
-                    assert_eq!(
-                        field1.size, size1,
-                        "`ScalarPair` first field with bad size in {inner:#?}",
-                    );
-                    assert_eq!(
-                        field1.align.abi, align1,
-                        "`ScalarPair` first field with bad align in {inner:#?}",
-                    );
-                    assert!(
-                        matches!(field1.abi, Abi::Scalar(_)),
-                        "`ScalarPair` first field with bad ABI in {inner:#?}",
-                    );
-                    assert_eq!(
-                        offset2, field2_offset,
-                        "`ScalarPair` second field at bad offset in {inner:#?}",
-                    );
-                    assert_eq!(
-                        field2.size, size2,
-                        "`ScalarPair` second field with bad size in {inner:#?}",
-                    );
-                    assert_eq!(
-                        field2.align.abi, align2,
-                        "`ScalarPair` second field with bad align in {inner:#?}",
-                    );
-                    assert!(
-                        matches!(field2.abi, Abi::Scalar(_)),
-                        "`ScalarPair` second field with bad ABI in {inner:#?}",
-                    );
-                }
-                Abi::Vector { count, element } => {
-                    // No padding in vectors. Alignment can be strengthened, though.
-                    assert!(
-                        layout.layout.align().abi >= element.align(cx).abi,
-                        "alignment mismatch between ABI and layout in {layout:#?}"
-                    );
-                    let size = element.size(cx) * count;
-                    assert_eq!(
-                        layout.layout.size(),
-                        size.align_to(cx.data_layout().vector_align(size).abi),
-                        "size mismatch between ABI and layout in {layout:#?}"
-                    );
-                }
-                Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check.
-            }
-        }
-
-        check_layout_abi(cx, layout);
-
-        if let Variants::Multiple { variants, .. } = &layout.variants {
-            for variant in variants.iter() {
-                // No nested "multiple".
-                assert!(matches!(variant.variants(), Variants::Single { .. }));
-                // Variants should have the same or a smaller size as the full thing,
-                // and same for alignment.
-                if variant.size() > layout.size {
-                    bug!(
-                        "Type with size {} bytes has variant with size {} bytes: {layout:#?}",
-                        layout.size.bytes(),
-                        variant.size().bytes(),
-                    )
-                }
-                if variant.align().abi > layout.align.abi {
-                    bug!(
-                        "Type with alignment {} bytes has variant with alignment {} bytes: {layout:#?}",
-                        layout.align.abi.bytes(),
-                        variant.align().abi.bytes(),
-                    )
-                }
-                // Skip empty variants.
-                if variant.size() == Size::ZERO
-                    || variant.fields().count() == 0
-                    || variant.abi().is_uninhabited()
-                {
-                    // These are never actually accessed anyway, so we can skip the coherence check
-                    // for them. They also fail that check, since they have
-                    // `Aggregate`/`Uninhbaited` ABI even when the main type is
-                    // `Scalar`/`ScalarPair`. (Note that sometimes, variants with fields have size
-                    // 0, and sometimes, variants without fields have non-0 size.)
-                    continue;
-                }
-                // The top-level ABI and the ABI of the variants should be coherent.
-                let scalar_coherent = |s1: Scalar, s2: Scalar| {
-                    s1.size(cx) == s2.size(cx) && s1.align(cx) == s2.align(cx)
-                };
-                let abi_coherent = match (layout.abi, variant.abi()) {
-                    (Abi::Scalar(s1), Abi::Scalar(s2)) => scalar_coherent(s1, s2),
-                    (Abi::ScalarPair(a1, b1), Abi::ScalarPair(a2, b2)) => {
-                        scalar_coherent(a1, a2) && scalar_coherent(b1, b2)
-                    }
-                    (Abi::Uninhabited, _) => true,
-                    (Abi::Aggregate { .. }, _) => true,
-                    _ => false,
-                };
-                if !abi_coherent {
-                    bug!(
-                        "Variant ABI is incompatible with top-level ABI:\nvariant={:#?}\nTop-level: {layout:#?}",
-                        variant
-                    );
-                }
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 3f9871190..a42d05706 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -17,7 +17,7 @@ pub use self::IntVarValue::*;
 pub use self::Variance::*;
 use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
 use crate::metadata::ModChild;
-use crate::middle::privacy::AccessLevels;
+use crate::middle::privacy::EffectiveVisibilities;
 use crate::mir::{Body, GeneratorLayout};
 use crate::traits::{self, Reveal};
 use crate::ty;
@@ -26,6 +26,7 @@ use crate::ty::util::Discr;
 pub use adt::*;
 pub use assoc::*;
 pub use generics::*;
+use hir::OpaqueTyOrigin;
 use rustc_ast as ast;
 use rustc_ast::node_id::NodeMap;
 use rustc_attr as attr;
@@ -37,11 +38,13 @@ use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, LifetimeRes, Res};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap};
+use rustc_hir::definitions::Definitions;
 use rustc_hir::Node;
 use rustc_index::vec::IndexVec;
 use rustc_macros::HashStable;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::{Decodable, Encodable};
+use rustc_session::cstore::CrateStoreDyn;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{ExpnId, Span};
@@ -73,11 +76,11 @@ pub use self::closure::{
     CAPTURE_STRUCT_LOCAL,
 };
 pub use self::consts::{
-    Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
+    Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, UnevaluatedConst, ValTree,
 };
 pub use self::context::{
     tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
-    CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
+    CtxtInterners, DeducedParamAttrs, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
     GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
     UserTypeAnnotationIndex,
 };
@@ -89,9 +92,9 @@ pub use self::sty::BoundRegionKind::*;
 pub use self::sty::{
     Article, Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar,
     BoundVariableKind, CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid,
-    EarlyBinder, EarlyBoundRegion, ExistentialPredicate, ExistentialProjection,
-    ExistentialTraitRef, FnSig, FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts,
-    InlineConstSubsts, InlineConstSubstsParts, ParamConst, ParamTy, PolyExistentialProjection,
+    EarlyBoundRegion, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig,
+    FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts,
+    InlineConstSubstsParts, ParamConst, ParamTy, PolyExistentialProjection,
     PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind,
     RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo,
 };
@@ -130,8 +133,8 @@ mod erase_regions;
 mod generics;
 mod impls_ty;
 mod instance;
-mod layout_sanity_check;
 mod list;
+mod opaque_types;
 mod parameterized;
 mod rvalue_scopes;
 mod structural_impls;
@@ -141,8 +144,15 @@ mod sty;
 
 pub type RegisteredTools = FxHashSet<Ident>;
 
-#[derive(Debug)]
 pub struct ResolverOutputs {
+    pub definitions: Definitions,
+    pub global_ctxt: ResolverGlobalCtxt,
+    pub ast_lowering: ResolverAstLowering,
+}
+
+#[derive(Debug)]
+pub struct ResolverGlobalCtxt {
+    pub cstore: Box<CrateStoreDyn>,
     pub visibilities: FxHashMap<LocalDefId, Visibility>,
     /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error.
     pub has_pub_restricted: bool,
@@ -150,7 +160,7 @@ pub struct ResolverOutputs {
     pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
     /// Reference span for definitions.
     pub source_span: IndexVec<LocalDefId, Span>,
-    pub access_levels: AccessLevels,
+    pub effective_visibilities: EffectiveVisibilities,
     pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
     pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
     pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
@@ -682,7 +692,7 @@ pub enum PredicateKind<'tcx> {
     Coerce(CoercePredicate<'tcx>),
 
     /// Constant initializer must evaluate successfully.
-    ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
+    ConstEvaluatable(ty::Const<'tcx>),
 
     /// Constants must be equal. The first component is the const that is expected.
     ConstEquate(Const<'tcx>, Const<'tcx>),
@@ -861,6 +871,11 @@ impl<'tcx> TraitPredicate<'tcx> {
             (BoundConstness::ConstIfConst, hir::Constness::NotConst) => false,
         }
     }
+
+    pub fn without_const(mut self) -> Self {
+        self.constness = BoundConstness::NotConst;
+        self
+    }
 }
 
 impl<'tcx> PolyTraitPredicate<'tcx> {
@@ -1296,6 +1311,106 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
             sub: sub_diag,
         });
     }
+
+    #[instrument(level = "debug", skip(tcx), ret)]
+    pub fn remap_generic_params_to_declaration_params(
+        self,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        tcx: TyCtxt<'tcx>,
+        // typeck errors have subpar spans for opaque types, so delay error reporting until borrowck.
+        ignore_errors: bool,
+        origin: OpaqueTyOrigin,
+    ) -> Self {
+        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(tcx, def_id.to_def_id());
+        debug!(?id_substs);
+
+        let map = substs.iter().zip(id_substs);
+
+        let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> = match origin {
+            // HACK: The HIR lowering for async fn does not generate
+            // any `+ Captures<'x>` bounds for the `impl Future<...>`, so all async fns with lifetimes
+            // would now fail to compile. We should probably just make hir lowering fill this in properly.
+            OpaqueTyOrigin::AsyncFn(_) => map.collect(),
+            OpaqueTyOrigin::FnReturn(_) | OpaqueTyOrigin::TyAlias => {
+                // Opaque types may only use regions that are bound. So for
+                // ```rust
+                // type Foo<'a, 'b, 'c> = impl Trait<'a> + 'b;
+                // ```
+                // we may not use `'c` in the hidden type.
+                struct OpaqueTypeLifetimeCollector<'tcx> {
+                    lifetimes: FxHashSet<ty::Region<'tcx>>,
+                }
+
+                impl<'tcx> ty::TypeVisitor<'tcx> for OpaqueTypeLifetimeCollector<'tcx> {
+                    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+                        self.lifetimes.insert(r);
+                        r.super_visit_with(self)
+                    }
+                }
+
+                let mut collector = OpaqueTypeLifetimeCollector { lifetimes: Default::default() };
+
+                for pred in tcx.bound_explicit_item_bounds(def_id.to_def_id()).transpose_iter() {
+                    let pred = pred.map_bound(|(pred, _)| *pred).subst(tcx, id_substs);
+
+                    trace!(pred=?pred.kind());
+
+                    // We only ignore opaque type substs if the opaque type is the outermost type.
+                    // The opaque type may be nested within itself via recursion in e.g.
+                    // type Foo<'a> = impl PartialEq<Foo<'a>>;
+                    // which thus mentions `'a` and should thus accept hidden types that borrow 'a
+                    // instead of requiring an additional `+ 'a`.
+                    match pred.kind().skip_binder() {
+                        ty::PredicateKind::Trait(TraitPredicate {
+                            trait_ref: ty::TraitRef { def_id: _, substs },
+                            constness: _,
+                            polarity: _,
+                        }) => {
+                            trace!(?substs);
+                            for subst in &substs[1..] {
+                                subst.visit_with(&mut collector);
+                            }
+                        }
+                        ty::PredicateKind::Projection(ty::ProjectionPredicate {
+                            projection_ty: ty::ProjectionTy { substs, item_def_id: _ },
+                            term,
+                        }) => {
+                            for subst in &substs[1..] {
+                                subst.visit_with(&mut collector);
+                            }
+                            term.visit_with(&mut collector);
+                        }
+                        _ => {
+                            pred.visit_with(&mut collector);
+                        }
+                    }
+                }
+                let lifetimes = collector.lifetimes;
+                trace!(?lifetimes);
+                map.filter(|(_, v)| {
+                    let ty::GenericArgKind::Lifetime(lt) = v.unpack() else {
+                        return true;
+                    };
+                    lifetimes.contains(&lt)
+                })
+                .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.
+        self.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span, ignore_errors))
+    }
 }
 
 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
@@ -2590,7 +2705,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
     closure::provide(providers);
     context::provide(providers);
     erase_regions::provide(providers);
-    layout::provide(providers);
+    inhabitedness::provide(providers);
     util::provide(providers);
     print::provide(providers);
     super::util::bug::provide(providers);
@@ -2598,7 +2713,6 @@ pub fn provide(providers: &mut ty::query::Providers) {
     *providers = ty::query::Providers {
         trait_impls_of: trait_def::trait_impls_of_provider,
         incoherent_impls: trait_def::incoherent_impls_provider,
-        type_uninhabited_from: inhabitedness::type_uninhabited_from,
         const_param_default: consts::const_param_default,
         vtable_allocation: vtable::vtable_allocation_provider,
         ..*providers
@@ -2667,8 +2781,9 @@ pub struct DestructuredConst<'tcx> {
 mod size_asserts {
     use super::*;
     use rustc_data_structures::static_assert_size;
-    // These are in alphabetical order, which is easy to maintain.
+    // tidy-alphabetical-start
     static_assert_size!(PredicateS<'_>, 48);
     static_assert_size!(TyS<'_>, 40);
     static_assert_size!(WithStableHash<TyS<'_>>, 56);
+    // tidy-alphabetical-end
 }
diff --git a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
index 9db5a2894..ee13920d5 100644
--- a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
+++ b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
@@ -10,8 +10,7 @@
 use crate::mir;
 use crate::traits::query::NoSolution;
 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder};
-use crate::ty::subst::{Subst, SubstsRef};
-use crate::ty::{self, EarlyBinder, Ty, TyCtxt};
+use crate::ty::{self, EarlyBinder, SubstsRef, Ty, TyCtxt};
 
 #[derive(Debug, Copy, Clone, HashStable, TyEncodable, TyDecodable)]
 pub enum NormalizationError<'tcx> {
@@ -215,15 +214,6 @@ impl<'tcx> TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
     fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
         self.normalize_generic_arg_after_erasing_regions(c.into()).expect_const()
     }
-
-    #[inline]
-    fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
-        // FIXME: This *probably* needs canonicalization too!
-        let arg = self.param_env.and(c);
-        self.tcx
-            .try_normalize_mir_const_after_erasing_regions(arg)
-            .unwrap_or_else(|_| bug!("failed to normalize {:?}", c))
-    }
 }
 
 struct TryNormalizeAfterErasingRegionsFolder<'tcx> {
@@ -268,16 +258,4 @@ impl<'tcx> FallibleTypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'t
             Err(_) => Err(NormalizationError::Const(c)),
         }
     }
-
-    fn try_fold_mir_const(
-        &mut self,
-        c: mir::ConstantKind<'tcx>,
-    ) -> Result<mir::ConstantKind<'tcx>, Self::Error> {
-        // FIXME: This *probably* needs canonicalization too!
-        let arg = self.param_env.and(c);
-        match self.tcx.try_normalize_mir_const_after_erasing_regions(arg) {
-            Ok(c) => Ok(c),
-            Err(_) => Err(NormalizationError::ConstantKind(c)),
-        }
-    }
 }
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs
new file mode 100644
index 000000000..b05c63109
--- /dev/null
+++ b/compiler/rustc_middle/src/ty/opaque_types.rs
@@ -0,0 +1,218 @@
+use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
+use rustc_span::Span;
+
+/// Converts generic params of a TypeFoldable from one
+/// item's generics to another. Usually from a function's generics
+/// list to the opaque type's own generics.
+pub(super) struct ReverseMapper<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
+    /// see call sites to fold_kind_no_missing_regions_error
+    /// for an explanation of this field.
+    do_not_error: bool,
+
+    /// We do not want to emit any errors in typeck because
+    /// the spans in typeck are subpar at the moment.
+    /// Borrowck will do the same work again (this time with
+    /// lifetime information) and thus report better errors.
+    ignore_errors: bool,
+
+    /// Span of function being checked.
+    span: Span,
+}
+
+impl<'tcx> ReverseMapper<'tcx> {
+    pub(super) fn new(
+        tcx: TyCtxt<'tcx>,
+        map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>>,
+        span: Span,
+        ignore_errors: bool,
+    ) -> Self {
+        Self { tcx, map, do_not_error: false, ignore_errors, span }
+    }
+
+    fn fold_kind_no_missing_regions_error(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
+        assert!(!self.do_not_error);
+        self.do_not_error = true;
+        let kind = kind.fold_with(self);
+        self.do_not_error = false;
+        kind
+    }
+
+    fn fold_kind_normally(&mut self, kind: GenericArg<'tcx>) -> GenericArg<'tcx> {
+        assert!(!self.do_not_error);
+        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::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);
+            }
+        }
+
+        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.do_not_error => self.tcx.lifetimes.re_static,
+            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_no_missing_regions_error(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_no_missing_regions_error(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);
+                        if !self.ignore_errors {
+                            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 => {
+                        if !self.ignore_errors {
+                            self.tcx.sess.emit_err(ty::ConstNotUsedTraitAlias {
+                                ct: ct.to_string(),
+                                span: self.span,
+                            });
+                        }
+
+                        self.tcx().const_error(ct.ty())
+                    }
+                }
+            }
+
+            _ => ct,
+        }
+    }
+}
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index 9c8dc30e2..e1e705a92 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -1,3 +1,4 @@
+use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::{DefId, DefIndex};
 use rustc_index::vec::{Idx, IndexVec};
 
@@ -29,6 +30,10 @@ impl<I: Idx + 'static, T: ParameterizedOverTcx> ParameterizedOverTcx for IndexVe
     type Value<'tcx> = IndexVec<I, T::Value<'tcx>>;
 }
 
+impl<I: 'static, T: ParameterizedOverTcx> ParameterizedOverTcx for FxHashMap<I, T> {
+    type Value<'tcx> = FxHashMap<I, T::Value<'tcx>>;
+}
+
 impl<T: ParameterizedOverTcx> ParameterizedOverTcx for ty::Binder<'static, T> {
     type Value<'tcx> = ty::Binder<'tcx, T::Value<'tcx>>;
 }
@@ -56,6 +61,7 @@ trivially_parameterized_over_tcx! {
     crate::middle::resolve_lifetime::ObjectLifetimeDefault,
     crate::mir::ConstQualifs,
     ty::AssocItemContainer,
+    ty::DeducedParamAttrs,
     ty::Generics,
     ty::ImplPolarity,
     ty::ReprOptions,
@@ -77,6 +83,7 @@ trivially_parameterized_over_tcx! {
     rustc_hir::def::DefKind,
     rustc_hir::def_id::DefIndex,
     rustc_hir::definitions::DefKey,
+    rustc_index::bit_set::BitSet<u32>,
     rustc_index::bit_set::FiniteBitSet<u32>,
     rustc_session::cstore::ForeignModule,
     rustc_session::cstore::LinkagePreference,
diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs
index d57cf8f01..44b9548db 100644
--- a/compiler/rustc_middle/src/ty/print/mod.rs
+++ b/compiler/rustc_middle/src/ty/print/mod.rs
@@ -1,9 +1,9 @@
-use crate::ty::subst::{GenericArg, Subst};
+use crate::ty::GenericArg;
 use crate::ty::{self, DefIdTree, Ty, TyCtxt};
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sso::SsoHashSet;
-use rustc_hir::def_id::{CrateNum, DefId};
+use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
 
 // `pretty` is a separate module only for organization.
@@ -325,3 +325,12 @@ impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Const<'tcx> {
         cx.print_const(*self)
     }
 }
+
+// This is only used by query descriptions
+pub fn describe_as_module(def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
+    if def_id.is_top_level_module() {
+        "top-level module".to_string()
+    } else {
+        format!("module `{}`", tcx.def_path_str(def_id.to_def_id()))
+    }
+}
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 97bddb93e..ef9aa236b 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1,9 +1,9 @@
 use crate::mir::interpret::{AllocRange, GlobalAlloc, Pointer, Provenance, Scalar};
-use crate::ty::subst::{GenericArg, GenericArgKind, Subst};
 use crate::ty::{
     self, ConstInt, DefIdTree, ParamConst, ScalarInt, Term, TermKind, Ty, TyCtxt, TypeFoldable,
     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable,
 };
+use crate::ty::{GenericArg, GenericArgKind};
 use rustc_apfloat::ieee::{Double, Single};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::sso::SsoHashSet;
@@ -16,6 +16,7 @@ use rustc_session::cstore::{ExternCrate, ExternCrateSource};
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi;
+use smallvec::SmallVec;
 
 use std::cell::Cell;
 use std::char;
@@ -62,6 +63,7 @@ thread_local! {
     static NO_TRIMMED_PATH: Cell<bool> = const { Cell::new(false) };
     static NO_QUERIES: Cell<bool> = const { Cell::new(false) };
     static NO_VISIBLE_PATH: Cell<bool> = const { Cell::new(false) };
+    static NO_VERBOSE_CONSTANTS: Cell<bool> = const { Cell::new(false) };
 }
 
 macro_rules! define_helper {
@@ -116,6 +118,9 @@ define_helper!(
     /// Prevent selection of visible paths. `Display` impl of DefId will prefer
     /// visible (public) reexports of types as paths.
     fn with_no_visible_paths(NoVisibleGuard, NO_VISIBLE_PATH);
+    /// Prevent verbose printing of constants. Verbose printing of constants is
+    /// never desirable in some contexts like `std::any::type_name`.
+    fn with_no_verbose_constants(NoVerboseConstantsGuard, NO_VERBOSE_CONSTANTS);
 );
 
 /// The "region highlights" are used to control region printing during
@@ -637,7 +642,9 @@ pub trait PrettyPrinter<'tcx>:
                 p!(print_def_path(def_id, &[]));
             }
             ty::Projection(ref data) => {
-                if self.tcx().def_kind(data.item_def_id) == DefKind::ImplTraitPlaceholder {
+                if !(self.tcx().sess.verbose() || NO_QUERIES.with(|q| q.get()))
+                    && self.tcx().def_kind(data.item_def_id) == DefKind::ImplTraitPlaceholder
+                {
                     return self.pretty_print_opaque_impl_type(data.item_def_id, data.substs);
                 } else {
                     p!(print(data))
@@ -756,7 +763,7 @@ pub trait PrettyPrinter<'tcx>:
             }
             ty::Array(ty, sz) => {
                 p!("[", print(ty), "; ");
-                if self.tcx().sess.verbose() {
+                if !NO_VERBOSE_CONSTANTS.with(|flag| flag.get()) && self.tcx().sess.verbose() {
                     p!(write("{:?}", sz));
                 } else if let ty::ConstKind::Unevaluated(..) = sz.kind() {
                     // Do not try to evaluate unevaluated constants. If we are const evaluating an
@@ -792,9 +799,9 @@ pub trait PrettyPrinter<'tcx>:
         let mut traits = FxIndexMap::default();
         let mut fn_traits = FxIndexMap::default();
         let mut is_sized = false;
+        let mut lifetimes = SmallVec::<[ty::Region<'tcx>; 1]>::new();
 
-        for predicate in bounds.transpose_iter().map(|e| e.map_bound(|(p, _)| *p)) {
-            let predicate = predicate.subst(tcx, substs);
+        for (predicate, _) in bounds.subst_iter_copied(tcx, substs) {
             let bound_predicate = predicate.kind();
 
             match bound_predicate.skip_binder() {
@@ -823,6 +830,9 @@ pub trait PrettyPrinter<'tcx>:
                         &mut fn_traits,
                     );
                 }
+                ty::PredicateKind::TypeOutlives(outlives) => {
+                    lifetimes.push(outlives.1);
+                }
                 _ => {}
             }
         }
@@ -927,7 +937,7 @@ pub trait PrettyPrinter<'tcx>:
                         // unless we can find out what generator return type it comes from.
                         let term = if let Some(ty) = term.skip_binder().ty()
                             && let ty::Projection(proj) = ty.kind()
-                            && let assoc = tcx.associated_item(proj.item_def_id)
+                            && let Some(assoc) = tcx.opt_associated_item(proj.item_def_id)
                             && assoc.trait_container(tcx) == tcx.lang_items().gen_trait()
                             && assoc.name == rustc_span::sym::Return
                         {
@@ -976,6 +986,11 @@ pub trait PrettyPrinter<'tcx>:
             write!(self, "Sized")?;
         }
 
+        for re in lifetimes {
+            write!(self, " + ")?;
+            self = self.print_region(re)?;
+        }
+
         Ok(self)
     }
 
@@ -1088,17 +1103,9 @@ pub trait PrettyPrinter<'tcx>:
                         .generics_of(principal.def_id)
                         .own_substs_no_defaults(cx.tcx(), principal.substs);
 
-                    // Don't print `'_` if there's no unerased regions.
-                    let print_regions = args.iter().any(|arg| match arg.unpack() {
-                        GenericArgKind::Lifetime(r) => !r.is_erased(),
-                        _ => false,
-                    });
-                    let mut args = args.iter().cloned().filter(|arg| match arg.unpack() {
-                        GenericArgKind::Lifetime(_) => print_regions,
-                        _ => true,
-                    });
                     let mut projections = predicates.projection_bounds();
 
+                    let mut args = args.iter().cloned();
                     let arg0 = args.next();
                     let projection0 = projections.next();
                     if arg0.is_some() || projection0.is_some() {
@@ -1178,7 +1185,7 @@ pub trait PrettyPrinter<'tcx>:
     ) -> Result<Self::Const, Self::Error> {
         define_scoped_cx!(self);
 
-        if self.tcx().sess.verbose() {
+        if !NO_VERBOSE_CONSTANTS.with(|flag| flag.get()) && self.tcx().sess.verbose() {
             p!(write("Const({:?}: {:?})", ct.kind(), ct.ty()));
             return Ok(self);
         }
@@ -1201,9 +1208,7 @@ pub trait PrettyPrinter<'tcx>:
         }
 
         match ct.kind() {
-            ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }) => {
-                assert_eq!(promoted, ());
-
+            ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }) => {
                 match self.tcx().def_kind(def.did) {
                     DefKind::Static(..) | DefKind::Const | DefKind::AssocConst => {
                         p!(print_value_path(def.did, substs))
@@ -1415,7 +1420,7 @@ pub trait PrettyPrinter<'tcx>:
     ) -> Result<Self::Const, Self::Error> {
         define_scoped_cx!(self);
 
-        if self.tcx().sess.verbose() {
+        if !NO_VERBOSE_CONSTANTS.with(|flag| flag.get()) && self.tcx().sess.verbose() {
             p!(write("ValTree({:?}: ", valtree), print(ty), ")");
             return Ok(self);
         }
@@ -1572,7 +1577,9 @@ pub struct FmtPrinterData<'a, 'tcx> {
     in_value: bool,
     pub print_alloc_ids: bool,
 
+    // set of all named (non-anonymous) region names
     used_region_names: FxHashSet<Symbol>,
+
     region_index: usize,
     binder_depth: usize,
     printed_type_count: usize,
@@ -1847,22 +1854,11 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
     ) -> Result<Self::Path, Self::Error> {
         self = print_prefix(self)?;
 
-        // Don't print `'_` if there's no unerased regions.
-        let print_regions = self.tcx.sess.verbose()
-            || args.iter().any(|arg| match arg.unpack() {
-                GenericArgKind::Lifetime(r) => !r.is_erased(),
-                _ => false,
-            });
-        let args = args.iter().cloned().filter(|arg| match arg.unpack() {
-            GenericArgKind::Lifetime(_) => print_regions,
-            _ => true,
-        });
-
-        if args.clone().next().is_some() {
+        if args.first().is_some() {
             if self.in_value {
                 write!(self, "::")?;
             }
-            self.generic_delimiters(|cx| cx.comma_sep(args))
+            self.generic_delimiters(|cx| cx.comma_sep(args.iter().cloned()))
         } else {
             Ok(self)
         }
@@ -2074,7 +2070,14 @@ struct RegionFolder<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     current_index: ty::DebruijnIndex,
     region_map: BTreeMap<ty::BoundRegion, ty::Region<'tcx>>,
-    name: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
+    name: &'a mut (
+                dyn FnMut(
+        Option<ty::DebruijnIndex>, // Debruijn index of the folded late-bound region
+        ty::DebruijnIndex,         // Index corresponding to binder level
+        ty::BoundRegion,
+    ) -> ty::Region<'tcx>
+                    + 'a
+            ),
 }
 
 impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
@@ -2105,7 +2108,9 @@ impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         let name = &mut self.name;
         let region = match *r {
-            ty::ReLateBound(_, br) => *self.region_map.entry(br).or_insert_with(|| name(br)),
+            ty::ReLateBound(db, br) if db >= self.current_index => {
+                *self.region_map.entry(br).or_insert_with(|| name(Some(db), self.current_index, br))
+            }
             ty::RePlaceholder(ty::PlaceholderRegion { name: kind, .. }) => {
                 // If this is an anonymous placeholder, don't rename. Otherwise, in some
                 // async fns, we get a `for<'r> Send` bound
@@ -2114,7 +2119,10 @@ impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
                     _ => {
                         // Index doesn't matter, since this is just for naming and these never get bound
                         let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind };
-                        *self.region_map.entry(br).or_insert_with(|| name(br))
+                        *self
+                            .region_map
+                            .entry(br)
+                            .or_insert_with(|| name(None, self.current_index, br))
                     }
                 }
             }
@@ -2139,23 +2147,31 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
     where
         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
     {
-        fn name_by_region_index(index: usize) -> Symbol {
-            match index {
-                0 => Symbol::intern("'r"),
-                1 => Symbol::intern("'s"),
-                i => Symbol::intern(&format!("'t{}", i - 2)),
+        fn name_by_region_index(
+            index: usize,
+            available_names: &mut Vec<Symbol>,
+            num_available: usize,
+        ) -> Symbol {
+            if let Some(name) = available_names.pop() {
+                name
+            } else {
+                Symbol::intern(&format!("'z{}", index - num_available))
             }
         }
 
+        debug!("name_all_regions");
+
         // Replace any anonymous late-bound regions with named
         // variants, using new unique identifiers, so that we can
         // clearly differentiate between named and unnamed regions in
         // the output. We'll probably want to tweak this over time to
         // decide just how much information to give.
         if self.binder_depth == 0 {
-            self.prepare_late_bound_region_info(value);
+            self.prepare_region_info(value);
         }
 
+        debug!("self.used_region_names: {:?}", &self.used_region_names);
+
         let mut empty = true;
         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
             let w = if empty {
@@ -2172,13 +2188,30 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 
         define_scoped_cx!(self);
 
+        let possible_names =
+            ('a'..='z').rev().map(|s| Symbol::intern(&format!("'{s}"))).collect::<Vec<_>>();
+
+        let mut available_names = possible_names
+            .into_iter()
+            .filter(|name| !self.used_region_names.contains(&name))
+            .collect::<Vec<_>>();
+        debug!(?available_names);
+        let num_available = available_names.len();
+
         let mut region_index = self.region_index;
-        let mut next_name = |this: &Self| loop {
-            let name = name_by_region_index(region_index);
-            region_index += 1;
-            if !this.used_region_names.contains(&name) {
-                break name;
+        let mut next_name = |this: &Self| {
+            let mut name;
+
+            loop {
+                name = name_by_region_index(region_index, &mut available_names, num_available);
+                region_index += 1;
+
+                if !this.used_region_names.contains(&name) {
+                    break;
+                }
             }
+
+            name
         };
 
         // If we want to print verbosely, then print *all* binders, even if they
@@ -2199,6 +2232,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         ty::BrAnon(_) | ty::BrEnv => {
                             start_or_continue(&mut self, "for<", ", ");
                             let name = next_name(&self);
+                            debug!(?name);
                             do_continue(&mut self, name);
                             ty::BrNamed(CRATE_DEF_ID.to_def_id(), name)
                         }
@@ -2227,24 +2261,63 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
             })
         } else {
             let tcx = self.tcx;
-            let mut name = |br: ty::BoundRegion| {
-                start_or_continue(&mut self, "for<", ", ");
-                let kind = match br.kind {
+
+            // Closure used in `RegionFolder` to create names for anonymous late-bound
+            // regions. We use two `DebruijnIndex`es (one for the currently folded
+            // late-bound region and the other for the binder level) to determine
+            // whether a name has already been created for the currently folded region,
+            // see issue #102392.
+            let mut name = |lifetime_idx: Option<ty::DebruijnIndex>,
+                            binder_level_idx: ty::DebruijnIndex,
+                            br: ty::BoundRegion| {
+                let (name, kind) = match br.kind {
                     ty::BrAnon(_) | ty::BrEnv => {
                         let name = next_name(&self);
-                        do_continue(&mut self, name);
-                        ty::BrNamed(CRATE_DEF_ID.to_def_id(), name)
+
+                        if let Some(lt_idx) = lifetime_idx {
+                            if lt_idx > binder_level_idx {
+                                let kind = ty::BrNamed(CRATE_DEF_ID.to_def_id(), name);
+                                return tcx.mk_region(ty::ReLateBound(
+                                    ty::INNERMOST,
+                                    ty::BoundRegion { var: br.var, kind },
+                                ));
+                            }
+                        }
+
+                        (name, ty::BrNamed(CRATE_DEF_ID.to_def_id(), name))
                     }
                     ty::BrNamed(def_id, kw::UnderscoreLifetime) => {
                         let name = next_name(&self);
-                        do_continue(&mut self, name);
-                        ty::BrNamed(def_id, name)
+
+                        if let Some(lt_idx) = lifetime_idx {
+                            if lt_idx > binder_level_idx {
+                                let kind = ty::BrNamed(def_id, name);
+                                return tcx.mk_region(ty::ReLateBound(
+                                    ty::INNERMOST,
+                                    ty::BoundRegion { var: br.var, kind },
+                                ));
+                            }
+                        }
+
+                        (name, ty::BrNamed(def_id, name))
                     }
                     ty::BrNamed(_, name) => {
-                        do_continue(&mut self, name);
-                        br.kind
+                        if let Some(lt_idx) = lifetime_idx {
+                            if lt_idx > binder_level_idx {
+                                let kind = br.kind;
+                                return tcx.mk_region(ty::ReLateBound(
+                                    ty::INNERMOST,
+                                    ty::BoundRegion { var: br.var, kind },
+                                ));
+                            }
+                        }
+
+                        (name, br.kind)
                     }
                 };
+
+                start_or_continue(&mut self, "for<", ", ");
+                do_continue(&mut self, name);
                 tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind }))
             };
             let mut folder = RegionFolder {
@@ -2292,29 +2365,37 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
         Ok(inner)
     }
 
-    fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
+    fn prepare_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
     where
         T: TypeVisitable<'tcx>,
     {
-        struct LateBoundRegionNameCollector<'a, 'tcx> {
-            used_region_names: &'a mut FxHashSet<Symbol>,
+        struct RegionNameCollector<'tcx> {
+            used_region_names: FxHashSet<Symbol>,
             type_collector: SsoHashSet<Ty<'tcx>>,
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_, 'tcx> {
+        impl<'tcx> RegionNameCollector<'tcx> {
+            fn new() -> Self {
+                RegionNameCollector {
+                    used_region_names: Default::default(),
+                    type_collector: SsoHashSet::new(),
+                }
+            }
+        }
+
+        impl<'tcx> ty::visit::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
             type BreakTy = ();
 
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
                 trace!("address: {:p}", r.0.0);
-                if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r {
-                    self.used_region_names.insert(name);
-                } else if let ty::RePlaceholder(ty::PlaceholderRegion {
-                    name: ty::BrNamed(_, name),
-                    ..
-                }) = *r
-                {
+
+                // Collect all named lifetimes. These allow us to prevent duplication
+                // of already existing lifetime names when introducing names for
+                // anonymous late-bound regions.
+                if let Some(name) = r.get_name() {
                     self.used_region_names.insert(name);
                 }
+
                 r.super_visit_with(self)
             }
 
@@ -2330,12 +2411,9 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
             }
         }
 
-        self.used_region_names.clear();
-        let mut collector = LateBoundRegionNameCollector {
-            used_region_names: &mut self.used_region_names,
-            type_collector: SsoHashSet::new(),
-        };
+        let mut collector = RegionNameCollector::new();
         value.visit_with(&mut collector);
+        self.used_region_names = collector.used_region_names;
         self.region_index = 0;
     }
 }
@@ -2637,8 +2715,8 @@ define_print_and_forward_display! {
                 print_value_path(closure_def_id, &[]),
                 write("` implements the trait `{}`", kind))
             }
-            ty::PredicateKind::ConstEvaluatable(uv) => {
-                p!("the constant `", print_value_path(uv.def.did, uv.substs), "` can be evaluated")
+            ty::PredicateKind::ConstEvaluatable(ct) => {
+                p!("the constant `", print(ct), "` can be evaluated")
             }
             ty::PredicateKind::ConstEquate(c1, c2) => {
                 p!("the constant `", print(c1), "` equals `", print(c2), "`")
@@ -2662,7 +2740,7 @@ fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, N
     // Iterate all local crate items no matter where they are defined.
     let hir = tcx.hir();
     for id in hir.items() {
-        if matches!(tcx.def_kind(id.def_id), DefKind::Use) {
+        if matches!(tcx.def_kind(id.owner_id), DefKind::Use) {
             continue;
         }
 
@@ -2671,7 +2749,7 @@ fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, N
             continue;
         }
 
-        let def_id = item.def_id.to_def_id();
+        let def_id = item.owner_id.to_def_id();
         let ns = tcx.def_kind(def_id).ns().unwrap_or(Namespace::TypeNS);
         collect_fn(&item.ident, ns, def_id);
     }
diff --git a/compiler/rustc_middle/src/ty/query.rs b/compiler/rustc_middle/src/ty/query.rs
index a300a8df2..ec90590ad 100644
--- a/compiler/rustc_middle/src/ty/query.rs
+++ b/compiler/rustc_middle/src/ty/query.rs
@@ -1,11 +1,11 @@
 use crate::dep_graph;
 use crate::infer::canonical::{self, Canonical};
-use crate::lint::LintLevelMap;
+use crate::lint::LintExpectation;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use crate::middle::lib_features::LibFeatures;
-use crate::middle::privacy::AccessLevels;
+use crate::middle::privacy::EffectiveVisibilities;
 use crate::middle::resolve_lifetime::{ObjectLifetimeDefault, Region, ResolveLifetimes};
 use crate::middle::stability::{self, DeprecationEntry};
 use crate::mir;
@@ -32,7 +32,7 @@ use crate::ty::layout::TyAndLayout;
 use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::util::AlwaysRequiresDrop;
 use crate::ty::GeneratorDiagnosticData;
-use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
+use crate::ty::{self, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
 use rustc_ast as ast;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_attr as attr;
@@ -40,17 +40,19 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::unord::UnordSet;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, LocalDefId};
+use rustc_hir::hir_id::OwnerId;
 use rustc_hir::lang_items::{LangItem, LanguageItems};
 use rustc_hir::{Crate, ItemLocalId, TraitCandidate};
 use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::cstore::{CrateDepKind, CrateSource};
 use rustc_session::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
-use rustc_session::utils::NativeLibKind;
+use rustc_session::lint::LintExpectationId;
 use rustc_session::Limits;
 use rustc_span::symbol::Symbol;
 use rustc_span::{Span, DUMMY_SP};
@@ -275,8 +277,9 @@ macro_rules! define_callbacks {
             fn default() -> Self {
                 Providers {
                     $($name: |_, key| bug!(
-                        "`tcx.{}({:?})` unsupported by its crate; \
-                         perhaps the `{}` query was never assigned a provider function",
+                        "`tcx.{}({:?})` is not supported for external or local crate;\n
+                        hint: Queries can be either made to the local crate, or the external crate. This error means you tried to use it for one that's not supported (likely the local crate).\n
+                        If that's not the case, {} was likely never assigned to a provider function.\n",
                         stringify!($name),
                         key,
                         stringify!($name),
@@ -335,7 +338,7 @@ macro_rules! define_callbacks {
 rustc_query_append! { define_callbacks! }
 
 mod sealed {
-    use super::{DefId, LocalDefId};
+    use super::{DefId, LocalDefId, OwnerId};
 
     /// An analogue of the `Into` trait that's intended only for query parameters.
     ///
@@ -365,6 +368,13 @@ mod sealed {
             self.to_def_id()
         }
     }
+
+    impl IntoQueryParam<DefId> for OwnerId {
+        #[inline(always)]
+        fn into_query_param(self) -> DefId {
+            self.to_def_id()
+        }
+    }
 }
 
 use sealed::IntoQueryParam;
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index 61c34730d..b25b4bd4f 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -5,8 +5,8 @@
 //! subtyping, type equality, etc.
 
 use crate::ty::error::{ExpectedFound, TypeError};
-use crate::ty::subst::{GenericArg, GenericArgKind, Subst, SubstsRef};
 use crate::ty::{self, ImplSubject, Term, TermKind, Ty, TyCtxt, TypeFoldable};
+use crate::ty::{GenericArg, GenericArgKind, SubstsRef};
 use rustc_hir as ast;
 use rustc_hir::def_id::DefId;
 use rustc_span::DUMMY_SP;
@@ -632,11 +632,7 @@ pub fn super_relate_consts<'tcx, R: TypeRelation<'tcx>>(
         // While this is slightly incorrect, it shouldn't matter for `min_const_generics`
         // and is the better alternative to waiting until `generic_const_exprs` can
         // be stabilized.
-        (ty::ConstKind::Unevaluated(au), ty::ConstKind::Unevaluated(bu))
-            if au.def == bu.def && au.promoted == bu.promoted =>
-        {
-            assert_eq!(au.promoted, ());
-
+        (ty::ConstKind::Unevaluated(au), ty::ConstKind::Unevaluated(bu)) if au.def == bu.def => {
             let substs = relation.relate_with_variance(
                 ty::Variance::Invariant,
                 ty::VarianceDiagInfo::default(),
@@ -644,11 +640,7 @@ pub fn super_relate_consts<'tcx, R: TypeRelation<'tcx>>(
                 bu.substs,
             )?;
             return Ok(tcx.mk_const(ty::ConstS {
-                kind: ty::ConstKind::Unevaluated(ty::Unevaluated {
-                    def: au.def,
-                    substs,
-                    promoted: (),
-                }),
+                kind: ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def: au.def, substs }),
                 ty: a.ty(),
             }));
         }
diff --git a/compiler/rustc_middle/src/ty/rvalue_scopes.rs b/compiler/rustc_middle/src/ty/rvalue_scopes.rs
index e86dafae3..e79b79a25 100644
--- a/compiler/rustc_middle/src/ty/rvalue_scopes.rs
+++ b/compiler/rustc_middle/src/ty/rvalue_scopes.rs
@@ -3,7 +3,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir as hir;
 
 /// `RvalueScopes` is a mapping from sub-expressions to _extended_ lifetime as determined by
-/// rules laid out in `rustc_typeck::check::rvalue_scopes`.
+/// rules laid out in `rustc_hir_analysis::check::rvalue_scopes`.
 #[derive(TyEncodable, TyDecodable, Clone, Debug, Default, Eq, PartialEq, HashStable)]
 pub struct RvalueScopes {
     map: FxHashMap<hir::ItemLocalId, Option<Scope>>,
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 84d6a8b97..2cad333e3 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -166,8 +166,8 @@ impl<'tcx> fmt::Debug for ty::PredicateKind<'tcx> {
             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
             }
-            ty::PredicateKind::ConstEvaluatable(uv) => {
-                write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs)
+            ty::PredicateKind::ConstEvaluatable(ct) => {
+                write!(f, "ConstEvaluatable({ct:?})")
             }
             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
@@ -560,18 +560,6 @@ impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<[T]> {
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::EarlyBinder<T> {
-    fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        self.try_map_bound(|ty| ty.try_fold_with(folder))
-    }
-}
-
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for ty::EarlyBinder<T> {
-    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.as_ref().0.visit_with(visitor)
-    }
-}
-
 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_binder(self)
@@ -844,45 +832,8 @@ impl<'tcx> TypeVisitable<'tcx> for InferConst<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
-    fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        folder.try_fold_unevaluated(self)
-    }
-}
-
-impl<'tcx> TypeVisitable<'tcx> for ty::Unevaluated<'tcx> {
-    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        visitor.visit_unevaluated(*self)
-    }
-}
-
-impl<'tcx> TypeSuperFoldable<'tcx> for ty::Unevaluated<'tcx> {
-    fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
-        self,
-        folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        Ok(ty::Unevaluated {
-            def: self.def,
-            substs: self.substs.try_fold_with(folder)?,
-            promoted: self.promoted,
-        })
-    }
-}
-
-impl<'tcx> TypeSuperVisitable<'tcx> for ty::Unevaluated<'tcx> {
+impl<'tcx> TypeSuperVisitable<'tcx> for ty::UnevaluatedConst<'tcx> {
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.substs.visit_with(visitor)
     }
 }
-
-impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
-    fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        Ok(self.expand().try_fold_with(folder)?.shrink())
-    }
-}
-
-impl<'tcx> TypeVisitable<'tcx> for ty::Unevaluated<'tcx, ()> {
-    fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
-        self.expand().visit_with(visitor)
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 36e560850..cf420bafe 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -3,7 +3,7 @@
 #![allow(rustc::usage_of_ty_tykind)]
 
 use crate::infer::canonical::Canonical;
-use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
+use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
 use crate::ty::visit::ValidateBoundVars;
 use crate::ty::InferTy::*;
 use crate::ty::{
@@ -19,7 +19,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_index::vec::Idx;
 use rustc_macros::HashStable;
-use rustc_span::symbol::{kw, Symbol};
+use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_target::abi::VariantIdx;
 use rustc_target::spec::abi;
 use std::borrow::Cow;
@@ -85,6 +85,17 @@ impl BoundRegionKind {
             _ => false,
         }
     }
+
+    pub fn get_name(&self) -> Option<Symbol> {
+        if self.is_named() {
+            match *self {
+                BoundRegionKind::BrNamed(_, name) => return Some(name),
+                _ => unreachable!(),
+            }
+        }
+
+        None
+    }
 }
 
 pub trait Article {
@@ -304,7 +315,7 @@ impl<'tcx> ClosureSubsts<'tcx> {
     /// closure.
     // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
     // type is known at the time of the creation of `ClosureSubsts`,
-    // see `rustc_typeck::check::closure`.
+    // see `rustc_hir_analysis::check::closure`.
     pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
         self.split().closure_sig_as_fn_ptr_ty.expect_ty()
     }
@@ -551,7 +562,7 @@ impl<'tcx> GeneratorSubsts<'tcx> {
         layout.variant_fields.iter().map(move |variant| {
             variant
                 .iter()
-                .map(move |field| EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
+                .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
         })
     }
 
@@ -915,73 +926,6 @@ impl<'tcx> PolyExistentialTraitRef<'tcx> {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
-#[derive(Encodable, Decodable, HashStable)]
-pub struct EarlyBinder<T>(pub T);
-
-impl<T> EarlyBinder<T> {
-    pub fn as_ref(&self) -> EarlyBinder<&T> {
-        EarlyBinder(&self.0)
-    }
-
-    pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U>
-    where
-        F: FnOnce(&T) -> U,
-    {
-        self.as_ref().map_bound(f)
-    }
-
-    pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U>
-    where
-        F: FnOnce(T) -> U,
-    {
-        let value = f(self.0);
-        EarlyBinder(value)
-    }
-
-    pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E>
-    where
-        F: FnOnce(T) -> Result<U, E>,
-    {
-        let value = f(self.0)?;
-        Ok(EarlyBinder(value))
-    }
-
-    pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> {
-        EarlyBinder(value)
-    }
-}
-
-impl<T> EarlyBinder<Option<T>> {
-    pub fn transpose(self) -> Option<EarlyBinder<T>> {
-        self.0.map(|v| EarlyBinder(v))
-    }
-}
-
-impl<T, U> EarlyBinder<(T, U)> {
-    pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) {
-        (EarlyBinder(self.0.0), EarlyBinder(self.0.1))
-    }
-}
-
-pub struct EarlyBinderIter<T> {
-    t: T,
-}
-
-impl<T: IntoIterator> EarlyBinder<T> {
-    pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> {
-        EarlyBinderIter { t: self.0.into_iter() }
-    }
-}
-
-impl<T: Iterator> Iterator for EarlyBinderIter<T> {
-    type Item = EarlyBinder<T::Item>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.t.next().map(|i| EarlyBinder(i))
-    }
-}
-
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
 #[derive(HashStable)]
 pub enum BoundVariableKind {
@@ -1200,9 +1144,13 @@ pub struct ProjectionTy<'tcx> {
 
 impl<'tcx> ProjectionTy<'tcx> {
     pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
-        let parent = tcx.parent(self.item_def_id);
-        assert_eq!(tcx.def_kind(parent), DefKind::Trait);
-        parent
+        match tcx.def_kind(self.item_def_id) {
+            DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.item_def_id),
+            DefKind::ImplTraitPlaceholder => {
+                tcx.parent(tcx.impl_trait_in_trait_parent(self.item_def_id))
+            }
+            kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
+        }
     }
 
     /// Extracts the underlying trait reference and own substs from this projection.
@@ -1213,6 +1161,7 @@ impl<'tcx> ProjectionTy<'tcx> {
         tcx: TyCtxt<'tcx>,
     ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
         let def_id = tcx.parent(self.item_def_id);
+        assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
         let trait_generics = tcx.generics_of(def_id);
         (
             ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
@@ -1508,6 +1457,23 @@ impl<'tcx> Region<'tcx> {
         *self.0.0
     }
 
+    pub fn get_name(self) -> Option<Symbol> {
+        if self.has_name() {
+            let name = match *self {
+                ty::ReEarlyBound(ebr) => Some(ebr.name),
+                ty::ReLateBound(_, br) => br.kind.get_name(),
+                ty::ReFree(fr) => fr.bound_region.get_name(),
+                ty::ReStatic => Some(kw::StaticLifetime),
+                ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
+                _ => None,
+            };
+
+            return name;
+        }
+
+        None
+    }
+
     /// Is this region named by the user?
     pub fn has_name(self) -> bool {
         match *self {
@@ -2156,7 +2122,7 @@ impl<'tcx> Ty<'tcx> {
     ///
     /// Note that during type checking, we use an inference variable
     /// to represent the closure kind, because it has not yet been
-    /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
+    /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
     /// is complete, that type variable will be unified.
     pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
         match self.kind() {
@@ -2239,7 +2205,10 @@ impl<'tcx> Ty<'tcx> {
             // These aren't even `Clone`
             ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
 
-            ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
+            ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
+            | ty::Int(..)
+            | ty::Uint(..)
+            | ty::Float(..) => true,
 
             // The voldemort ZSTs are fine.
             ty::FnDef(..) => true,
@@ -2274,6 +2243,35 @@ impl<'tcx> Ty<'tcx> {
             }
         }
     }
+
+    // If `self` is a primitive, return its [`Symbol`].
+    pub fn primitive_symbol(self) -> Option<Symbol> {
+        match self.kind() {
+            ty::Bool => Some(sym::bool),
+            ty::Char => Some(sym::char),
+            ty::Float(f) => match f {
+                ty::FloatTy::F32 => Some(sym::f32),
+                ty::FloatTy::F64 => Some(sym::f64),
+            },
+            ty::Int(f) => match f {
+                ty::IntTy::Isize => Some(sym::isize),
+                ty::IntTy::I8 => Some(sym::i8),
+                ty::IntTy::I16 => Some(sym::i16),
+                ty::IntTy::I32 => Some(sym::i32),
+                ty::IntTy::I64 => Some(sym::i64),
+                ty::IntTy::I128 => Some(sym::i128),
+            },
+            ty::Uint(f) => match f {
+                ty::UintTy::Usize => Some(sym::usize),
+                ty::UintTy::U8 => Some(sym::u8),
+                ty::UintTy::U16 => Some(sym::u16),
+                ty::UintTy::U32 => Some(sym::u32),
+                ty::UintTy::U64 => Some(sym::u64),
+                ty::UintTy::U128 => Some(sym::u128),
+            },
+            _ => None,
+        }
+    }
 }
 
 /// Extra information about why we ended up with a particular variance.
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index 8e69bf067..0660e9b79 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -1,12 +1,12 @@
 // Type substitutions.
 
-use crate::mir;
 use crate::ty::codec::{TyDecoder, TyEncoder};
 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
 use crate::ty::sty::{ClosureSubsts, GeneratorSubsts, InlineConstSubsts};
 use crate::ty::visit::{TypeVisitable, TypeVisitor};
 use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
 
+use rustc_data_structures::captures::Captures;
 use rustc_data_structures::intern::{Interned, WithStableHash};
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
@@ -189,6 +189,14 @@ impl<'tcx> GenericArg<'tcx> {
             _ => bug!("expected a const, but found another kind"),
         }
     }
+
+    pub fn is_non_region_infer(self) -> bool {
+        match self.unpack() {
+            GenericArgKind::Lifetime(_) => false,
+            GenericArgKind::Type(ty) => ty.is_ty_infer(),
+            GenericArgKind::Const(ct) => ct.is_ct_infer(),
+        }
+    }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {
@@ -492,23 +500,107 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 }
 
 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &'tcx ty::List<T> {
+    #[inline]
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
 
-// Just call `foo.subst(tcx, substs)` to perform a substitution across `foo`.
-#[rustc_on_unimplemented(message = "Calling `subst` must now be done through an `EarlyBinder`")]
-pub trait Subst<'tcx>: Sized {
-    type Inner;
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[derive(Encodable, Decodable, HashStable)]
+pub struct EarlyBinder<T>(pub T);
+
+/// For early binders, you should first call `subst` before using any visitors.
+impl<'tcx, T> !TypeFoldable<'tcx> for ty::EarlyBinder<T> {}
+impl<'tcx, T> !TypeVisitable<'tcx> for ty::EarlyBinder<T> {}
+
+impl<T> EarlyBinder<T> {
+    pub fn as_ref(&self) -> EarlyBinder<&T> {
+        EarlyBinder(&self.0)
+    }
 
-    fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self::Inner;
+    pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U>
+    where
+        F: FnOnce(&T) -> U,
+    {
+        self.as_ref().map_bound(f)
+    }
+
+    pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U>
+    where
+        F: FnOnce(T) -> U,
+    {
+        let value = f(self.0);
+        EarlyBinder(value)
+    }
+
+    pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E>
+    where
+        F: FnOnce(T) -> Result<U, E>,
+    {
+        let value = f(self.0)?;
+        Ok(EarlyBinder(value))
+    }
+
+    pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> {
+        EarlyBinder(value)
+    }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> Subst<'tcx> for ty::EarlyBinder<T> {
-    type Inner = T;
+impl<T> EarlyBinder<Option<T>> {
+    pub fn transpose(self) -> Option<EarlyBinder<T>> {
+        self.0.map(|v| EarlyBinder(v))
+    }
+}
+
+impl<T, U> EarlyBinder<(T, U)> {
+    pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) {
+        (EarlyBinder(self.0.0), EarlyBinder(self.0.1))
+    }
+}
 
-    fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self::Inner {
+impl<'tcx, 's, T: IntoIterator<Item = I>, I: TypeFoldable<'tcx>> EarlyBinder<T> {
+    pub fn subst_iter(
+        self,
+        tcx: TyCtxt<'tcx>,
+        substs: &'s [GenericArg<'tcx>],
+    ) -> impl Iterator<Item = I> + Captures<'s> + Captures<'tcx> {
+        self.0.into_iter().map(move |t| EarlyBinder(t).subst(tcx, substs))
+    }
+}
+
+impl<'tcx, 's, 'a, T: IntoIterator<Item = &'a I>, I: Copy + TypeFoldable<'tcx> + 'a>
+    EarlyBinder<T>
+{
+    pub fn subst_iter_copied(
+        self,
+        tcx: TyCtxt<'tcx>,
+        substs: &'s [GenericArg<'tcx>],
+    ) -> impl Iterator<Item = I> + Captures<'s> + Captures<'tcx> + Captures<'a> {
+        self.0.into_iter().map(move |t| EarlyBinder(*t).subst(tcx, substs))
+    }
+}
+
+pub struct EarlyBinderIter<T> {
+    t: T,
+}
+
+impl<T: IntoIterator> EarlyBinder<T> {
+    pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> {
+        EarlyBinderIter { t: self.0.into_iter() }
+    }
+}
+
+impl<T: Iterator> Iterator for EarlyBinderIter<T> {
+    type Item = EarlyBinder<T::Item>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.t.next().map(|i| EarlyBinder(i))
+    }
+}
+
+impl<'tcx, T: TypeFoldable<'tcx>> ty::EarlyBinder<T> {
+    pub fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> T {
         let mut folder = SubstFolder { tcx, substs, binders_passed: 0 };
         self.0.fold_with(&mut folder)
     }
@@ -544,9 +636,21 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         #[cold]
         #[inline(never)]
-        fn region_param_out_of_range(data: ty::EarlyBoundRegion) -> ! {
+        fn region_param_out_of_range(data: ty::EarlyBoundRegion, substs: &[GenericArg<'_>]) -> ! {
             bug!(
-                "Region parameter out of range when substituting in region {} (index={})",
+                "Region parameter out of range when substituting in region {} (index={}, substs = {:?})",
+                data.name,
+                data.index,
+                substs,
+            )
+        }
+
+        #[cold]
+        #[inline(never)]
+        fn region_param_invalid(data: ty::EarlyBoundRegion, other: GenericArgKind<'_>) -> ! {
+            bug!(
+                "Unexpected parameter {:?} when substituting in region {} (index={})",
+                other,
                 data.name,
                 data.index
             )
@@ -562,7 +666,8 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
                 let rk = self.substs.get(data.index as usize).map(|k| k.unpack());
                 match rk {
                     Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
-                    _ => region_param_out_of_range(data),
+                    Some(other) => region_param_invalid(data, other),
+                    None => region_param_out_of_range(data, self.substs),
                 }
             }
             _ => r,
@@ -587,11 +692,6 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
             c.super_fold_with(self)
         }
     }
-
-    #[inline]
-    fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
-        c.super_fold_with(self)
-    }
 }
 
 impl<'a, 'tcx> SubstFolder<'a, 'tcx> {
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 23ad4d27d..f72e236ed 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -2,12 +2,11 @@
 
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::ty::layout::IntegerExt;
-use crate::ty::query::TyCtxtAt;
-use crate::ty::subst::{GenericArgKind, Subst, SubstsRef};
 use crate::ty::{
     self, DefIdTree, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
     TypeVisitable,
 };
+use crate::ty::{GenericArgKind, SubstsRef};
 use rustc_apfloat::Float as _;
 use rustc_ast as ast;
 use rustc_attr::{self as attr, SignedInt, UnsignedInt};
@@ -821,12 +820,8 @@ impl<'tcx> Ty<'tcx> {
     /// does copies even when the type actually doesn't satisfy the
     /// full requirements for the `Copy` trait (cc #29149) -- this
     /// winds up being reported as an error during NLL borrow check.
-    pub fn is_copy_modulo_regions(
-        self,
-        tcx_at: TyCtxtAt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> bool {
-        self.is_trivially_pure_clone_copy() || tcx_at.is_copy_raw(param_env.and(self))
+    pub fn is_copy_modulo_regions(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
+        self.is_trivially_pure_clone_copy() || tcx.is_copy_raw(param_env.and(self))
     }
 
     /// Checks whether values of this type `T` have a size known at
@@ -835,8 +830,8 @@ impl<'tcx> Ty<'tcx> {
     /// over-approximation in generic contexts, where one can have
     /// strange rules like `<T as Foo<'static>>::Bar: Sized` that
     /// actually carry lifetime requirements.
-    pub fn is_sized(self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
-        self.is_trivially_sized(tcx_at.tcx) || tcx_at.is_sized_raw(param_env.and(self))
+    pub fn is_sized(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
+        self.is_trivially_sized(tcx) || tcx.is_sized_raw(param_env.and(self))
     }
 
     /// Checks whether values of this type `T` implement the `Freeze`
@@ -846,8 +841,8 @@ impl<'tcx> Ty<'tcx> {
     /// optimization as well as the rules around static values. Note
     /// that the `Freeze` trait is not exposed to end users and is
     /// effectively an implementation detail.
-    pub fn is_freeze(self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
-        self.is_trivially_freeze() || tcx_at.is_freeze_raw(param_env.and(self))
+    pub fn is_freeze(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
+        self.is_trivially_freeze() || tcx.is_freeze_raw(param_env.and(self))
     }
 
     /// Fast path helper for testing if a type is `Freeze`.
@@ -886,8 +881,8 @@ impl<'tcx> Ty<'tcx> {
     }
 
     /// Checks whether values of this type `T` implement the `Unpin` trait.
-    pub fn is_unpin(self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
-        self.is_trivially_unpin() || tcx_at.is_unpin_raw(param_env.and(self))
+    pub fn is_unpin(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool {
+        self.is_trivially_unpin() || tcx.is_unpin_raw(param_env.and(self))
     }
 
     /// Fast path helper for testing if a type is `Unpin`.
@@ -958,7 +953,7 @@ impl<'tcx> Ty<'tcx> {
         }
     }
 
-    /// Checks if `ty` has has a significant drop.
+    /// Checks if `ty` has a significant drop.
     ///
     /// Note that this method can return false even if `ty` has a destructor
     /// attached; even if that is the case then the adt has been marked with
@@ -1289,12 +1284,24 @@ pub fn is_doc_hidden(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
         .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
 }
 
+/// Determines whether an item is annotated with `doc(notable_trait)`.
+pub fn is_doc_notable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+    tcx.get_attrs(def_id, sym::doc)
+        .filter_map(|attr| attr.meta_item_list())
+        .any(|items| items.iter().any(|item| item.has_name(sym::notable_trait)))
+}
+
 /// Determines whether an item is an intrinsic by Abi.
 pub fn is_intrinsic(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
     matches!(tcx.fn_sig(def_id).abi(), Abi::RustIntrinsic | Abi::PlatformIntrinsic)
 }
 
 pub fn provide(providers: &mut ty::query::Providers) {
-    *providers =
-        ty::query::Providers { normalize_opaque_types, is_doc_hidden, is_intrinsic, ..*providers }
+    *providers = ty::query::Providers {
+        normalize_opaque_types,
+        is_doc_hidden,
+        is_doc_notable_trait,
+        is_intrinsic,
+        ..*providers
+    }
 }
diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs
index 5f8cb5782..c09f71f9a 100644
--- a/compiler/rustc_middle/src/ty/visit.rs
+++ b/compiler/rustc_middle/src/ty/visit.rs
@@ -10,8 +10,7 @@
 //!
 //! There are three groups of traits involved in each traversal.
 //! - `TypeVisitable`. This is implemented once for many types, including:
-//!   - Types of interest, for which the the methods delegate to the
-//!     visitor.
+//!   - Types of interest, for which the methods delegate to the visitor.
 //!   - All other types, including generic containers like `Vec` and `Option`.
 //!     It defines a "skeleton" of how they should be visited.
 //! - `TypeSuperVisitable`. This is implemented only for each type of interest,
@@ -39,7 +38,6 @@
 //!     - ty.super_visit_with(visitor)
 //! - u.visit_with(visitor)
 //! ```
-use crate::mir;
 use crate::ty::{self, flags::FlagComputation, Binder, Ty, TyCtxt, TypeFlags};
 use rustc_errors::ErrorGuaranteed;
 
@@ -104,8 +102,8 @@ pub trait TypeVisitable<'tcx>: fmt::Debug + Clone {
             None
         }
     }
-    fn has_param_types_or_consts(&self) -> bool {
-        self.has_type_flags(TypeFlags::HAS_TY_PARAM | TypeFlags::HAS_CT_PARAM)
+    fn has_non_region_param(&self) -> bool {
+        self.has_type_flags(TypeFlags::NEEDS_SUBST - TypeFlags::HAS_RE_PARAM)
     }
     fn has_infer_regions(&self) -> bool {
         self.has_type_flags(TypeFlags::HAS_RE_INFER)
@@ -113,8 +111,8 @@ pub trait TypeVisitable<'tcx>: fmt::Debug + Clone {
     fn has_infer_types(&self) -> bool {
         self.has_type_flags(TypeFlags::HAS_TY_INFER)
     }
-    fn has_infer_types_or_consts(&self) -> bool {
-        self.has_type_flags(TypeFlags::HAS_TY_INFER | TypeFlags::HAS_CT_INFER)
+    fn has_non_region_infer(&self) -> bool {
+        self.has_type_flags(TypeFlags::NEEDS_INFER - TypeFlags::HAS_RE_INFER)
     }
     fn needs_infer(&self) -> bool {
         self.has_type_flags(TypeFlags::NEEDS_INFER)
@@ -199,17 +197,9 @@ pub trait TypeVisitor<'tcx>: Sized {
         c.super_visit_with(self)
     }
 
-    fn visit_unevaluated(&mut self, uv: ty::Unevaluated<'tcx>) -> ControlFlow<Self::BreakTy> {
-        uv.super_visit_with(self)
-    }
-
     fn visit_predicate(&mut self, p: ty::Predicate<'tcx>) -> ControlFlow<Self::BreakTy> {
         p.super_visit_with(self)
     }
-
-    fn visit_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> ControlFlow<Self::BreakTy> {
-        c.super_visit_with(self)
-    }
 }
 
 ///////////////////////////////////////////////////////////////////////////
@@ -597,18 +587,6 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor {
 
     #[inline]
     #[instrument(level = "trace", ret)]
-    fn visit_unevaluated(&mut self, uv: ty::Unevaluated<'tcx>) -> ControlFlow<Self::BreakTy> {
-        let flags = FlagComputation::for_unevaluated_const(uv);
-        trace!(r.flags=?flags);
-        if flags.intersects(self.flags) {
-            ControlFlow::Break(FoundFlags)
-        } else {
-            ControlFlow::CONTINUE
-        }
-    }
-
-    #[inline]
-    #[instrument(level = "trace", ret)]
     fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ControlFlow<Self::BreakTy> {
         debug!(
             "HasTypeFlagsVisitor: predicate={:?} predicate.flags={:?} self.flags={:?}",
diff --git a/compiler/rustc_middle/src/ty/walk.rs b/compiler/rustc_middle/src/ty/walk.rs
index a3e11bbf0..91db9698c 100644
--- a/compiler/rustc_middle/src/ty/walk.rs
+++ b/compiler/rustc_middle/src/ty/walk.rs
@@ -112,6 +112,22 @@ impl<'tcx> Ty<'tcx> {
     }
 }
 
+impl<'tcx> ty::Const<'tcx> {
+    /// Iterator that walks `self` and any types reachable from
+    /// `self`, in depth-first order. Note that just walks the types
+    /// that appear in `self`, it does not descend into the fields of
+    /// structs or variants. For example:
+    ///
+    /// ```text
+    /// isize => { isize }
+    /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
+    /// [isize] => { [isize], isize }
+    /// ```
+    pub fn walk(self) -> TypeWalker<'tcx> {
+        TypeWalker::new(self.into())
+    }
+}
+
 /// We push `GenericArg`s on the stack in reverse order so as to
 /// maintain a pre-order traversal. As of the time of this
 /// writing, the fact that the traversal is pre-order is not
diff --git a/compiler/rustc_middle/src/values.rs b/compiler/rustc_middle/src/values.rs
index 7fbe9ae2a..f4b4c3fb0 100644
--- a/compiler/rustc_middle/src/values.rs
+++ b/compiler/rustc_middle/src/values.rs
@@ -1,8 +1,18 @@
-use rustc_middle::ty::{self, AdtSizedConstraint, Ty, TyCtxt};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
+use rustc_hir as hir;
+use rustc_hir::def::DefKind;
+use rustc_middle::ty::Representability;
+use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
+use rustc_query_system::query::QueryInfo;
 use rustc_query_system::Value;
+use rustc_span::def_id::LocalDefId;
+use rustc_span::Span;
+
+use std::fmt::Write;
 
 impl<'tcx> Value<TyCtxt<'tcx>> for Ty<'_> {
-    fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
         // SAFETY: This is never called when `Self` is not `Ty<'tcx>`.
         // FIXME: Represent the above fact in the trait system somehow.
         unsafe { std::mem::transmute::<Ty<'tcx>, Ty<'_>>(tcx.ty_error()) }
@@ -10,7 +20,7 @@ impl<'tcx> Value<TyCtxt<'tcx>> for Ty<'_> {
 }
 
 impl<'tcx> Value<TyCtxt<'tcx>> for ty::SymbolName<'_> {
-    fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
         // SAFETY: This is never called when `Self` is not `SymbolName<'tcx>`.
         // FIXME: Represent the above fact in the trait system somehow.
         unsafe {
@@ -21,20 +31,8 @@ impl<'tcx> Value<TyCtxt<'tcx>> for ty::SymbolName<'_> {
     }
 }
 
-impl<'tcx> Value<TyCtxt<'tcx>> for AdtSizedConstraint<'_> {
-    fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
-        // SAFETY: This is never called when `Self` is not `AdtSizedConstraint<'tcx>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe {
-            std::mem::transmute::<AdtSizedConstraint<'tcx>, AdtSizedConstraint<'_>>(
-                AdtSizedConstraint(tcx.intern_type_list(&[tcx.ty_error()])),
-            )
-        }
-    }
-}
-
 impl<'tcx> Value<TyCtxt<'tcx>> for ty::Binder<'_, ty::FnSig<'_>> {
-    fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
         let err = tcx.ty_error();
         // FIXME(compiler-errors): It would be nice if we could get the
         // query key, so we could at least generate a fn signature that
@@ -52,3 +50,153 @@ impl<'tcx> Value<TyCtxt<'tcx>> for ty::Binder<'_, ty::FnSig<'_>> {
         unsafe { std::mem::transmute::<ty::PolyFnSig<'tcx>, ty::Binder<'_, ty::FnSig<'_>>>(fn_sig) }
     }
 }
+
+impl<'tcx> Value<TyCtxt<'tcx>> for Representability {
+    fn from_cycle_error(tcx: TyCtxt<'tcx>, cycle: &[QueryInfo]) -> Self {
+        let mut item_and_field_ids = Vec::new();
+        let mut representable_ids = FxHashSet::default();
+        for info in cycle {
+            if info.query.name == "representability"
+                && let Some(field_id) = info.query.def_id
+                && let Some(field_id) = field_id.as_local()
+                && let Some(DefKind::Field) = info.query.def_kind
+            {
+                let parent_id = tcx.parent(field_id.to_def_id());
+                let item_id = match tcx.def_kind(parent_id) {
+                    DefKind::Variant => tcx.parent(parent_id),
+                    _ => parent_id,
+                };
+                item_and_field_ids.push((item_id.expect_local(), field_id));
+            }
+        }
+        for info in cycle {
+            if info.query.name == "representability_adt_ty"
+                && let Some(def_id) = info.query.ty_adt_id
+                && let Some(def_id) = def_id.as_local()
+                && !item_and_field_ids.iter().any(|&(id, _)| id == def_id)
+            {
+                representable_ids.insert(def_id);
+            }
+        }
+        recursive_type_error(tcx, item_and_field_ids, &representable_ids);
+        Representability::Infinite
+    }
+}
+
+// item_and_field_ids should form a cycle where each field contains the
+// type in the next element in the list
+pub fn recursive_type_error(
+    tcx: TyCtxt<'_>,
+    mut item_and_field_ids: Vec<(LocalDefId, LocalDefId)>,
+    representable_ids: &FxHashSet<LocalDefId>,
+) {
+    const ITEM_LIMIT: usize = 5;
+
+    // Rotate the cycle so that the item with the lowest span is first
+    let start_index = item_and_field_ids
+        .iter()
+        .enumerate()
+        .min_by_key(|&(_, &(id, _))| tcx.def_span(id))
+        .unwrap()
+        .0;
+    item_and_field_ids.rotate_left(start_index);
+
+    let cycle_len = item_and_field_ids.len();
+    let show_cycle_len = cycle_len.min(ITEM_LIMIT);
+
+    let mut err_span = MultiSpan::from_spans(
+        item_and_field_ids[..show_cycle_len]
+            .iter()
+            .map(|(id, _)| tcx.def_span(id.to_def_id()))
+            .collect(),
+    );
+    let mut suggestion = Vec::with_capacity(show_cycle_len * 2);
+    for i in 0..show_cycle_len {
+        let (_, field_id) = item_and_field_ids[i];
+        let (next_item_id, _) = item_and_field_ids[(i + 1) % cycle_len];
+        // Find the span(s) that contain the next item in the cycle
+        let hir_id = tcx.hir().local_def_id_to_hir_id(field_id);
+        let hir::Node::Field(field) = tcx.hir().get(hir_id) else { bug!("expected field") };
+        let mut found = Vec::new();
+        find_item_ty_spans(tcx, field.ty, next_item_id, &mut found, representable_ids);
+
+        // Couldn't find the type. Maybe it's behind a type alias?
+        // In any case, we'll just suggest boxing the whole field.
+        if found.is_empty() {
+            found.push(field.ty.span);
+        }
+
+        for span in found {
+            err_span.push_span_label(span, "recursive without indirection");
+            // FIXME(compiler-errors): This suggestion might be erroneous if Box is shadowed
+            suggestion.push((span.shrink_to_lo(), "Box<".to_string()));
+            suggestion.push((span.shrink_to_hi(), ">".to_string()));
+        }
+    }
+    let items_list = {
+        let mut s = String::new();
+        for (i, (item_id, _)) in item_and_field_ids.iter().enumerate() {
+            let path = tcx.def_path_str(item_id.to_def_id());
+            write!(&mut s, "`{path}`").unwrap();
+            if i == (ITEM_LIMIT - 1) && cycle_len > ITEM_LIMIT {
+                write!(&mut s, " and {} more", cycle_len - 5).unwrap();
+                break;
+            }
+            if cycle_len > 1 && i < cycle_len - 2 {
+                s.push_str(", ");
+            } else if cycle_len > 1 && i == cycle_len - 2 {
+                s.push_str(" and ")
+            }
+        }
+        s
+    };
+    let mut err = struct_span_err!(
+        tcx.sess,
+        err_span,
+        E0072,
+        "recursive type{} {} {} infinite size",
+        pluralize!(cycle_len),
+        items_list,
+        pluralize!("has", cycle_len),
+    );
+    err.multipart_suggestion(
+        "insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle",
+        suggestion,
+        Applicability::HasPlaceholders,
+    );
+    err.emit();
+}
+
+fn find_item_ty_spans(
+    tcx: TyCtxt<'_>,
+    ty: &hir::Ty<'_>,
+    needle: LocalDefId,
+    spans: &mut Vec<Span>,
+    seen_representable: &FxHashSet<LocalDefId>,
+) {
+    match ty.kind {
+        hir::TyKind::Path(hir::QPath::Resolved(_, path)) => {
+            if let Some(def_id) = path.res.opt_def_id() {
+                let check_params = def_id.as_local().map_or(true, |def_id| {
+                    if def_id == needle {
+                        spans.push(ty.span);
+                    }
+                    seen_representable.contains(&def_id)
+                });
+                if check_params && let Some(args) = path.segments.last().unwrap().args {
+                    let params_in_repr = tcx.params_in_repr(def_id);
+                    for (i, arg) in args.args.iter().enumerate() {
+                        if let hir::GenericArg::Type(ty) = arg && params_in_repr.contains(i as u32) {
+                            find_item_ty_spans(tcx, ty, needle, spans, seen_representable);
+                        }
+                    }
+                }
+            }
+        }
+        hir::TyKind::Array(ty, _) => find_item_ty_spans(tcx, ty, needle, spans, seen_representable),
+        hir::TyKind::Tup(tys) => {
+            tys.iter().for_each(|ty| find_item_ty_spans(tcx, ty, needle, spans, seen_representable))
+        }
+        _ => {}
+    }
+}