Merging debian version 1.65.0+dfsg1-2.

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

12 files changed, 272 insertions, 243 deletions

diff --git a/compiler/rustc_hir/src/def.rs b/compiler/rustc_hir/src/def.rs
index be5b7eccb..e7c26bd72 100644
--- a/compiler/rustc_hir/src/def.rs
+++ b/compiler/rustc_hir/src/def.rs
@@ -45,8 +45,6 @@ pub enum NonMacroAttrKind {
     /// Single-segment custom attribute registered by a derive macro
     /// but used before that derive macro was expanded (deprecated).
     DeriveHelperCompat,
-    /// Single-segment custom attribute registered with `#[register_attr]`.
-    Registered,
 }
 
 /// What kind of definition something is; e.g., `mod` vs `struct`.
@@ -111,6 +109,8 @@ pub enum DefKind {
     InlineConst,
     /// Opaque type, aka `impl Trait`.
     OpaqueTy,
+    /// A return-position `impl Trait` in a trait definition
+    ImplTraitPlaceholder,
     Field,
     /// Lifetime parameter: the `'a` in `struct Foo<'a> { ... }`
     LifetimeParam,
@@ -140,6 +140,7 @@ impl DefKind {
                 panic!("impossible struct constructor")
             }
             DefKind::OpaqueTy => "opaque type",
+            DefKind::ImplTraitPlaceholder => "opaque type in trait",
             DefKind::TyAlias => "type alias",
             DefKind::TraitAlias => "trait alias",
             DefKind::AssocTy => "associated type",
@@ -219,7 +220,8 @@ impl DefKind {
             | DefKind::Use
             | DefKind::ForeignMod
             | DefKind::GlobalAsm
-            | DefKind::Impl => None,
+            | DefKind::Impl
+            | DefKind::ImplTraitPlaceholder => None,
         }
     }
 
@@ -256,6 +258,7 @@ impl DefKind {
             | DefKind::Use
             | DefKind::ForeignMod
             | DefKind::OpaqueTy
+            | DefKind::ImplTraitPlaceholder
             | DefKind::Impl
             | DefKind::Field
             | DefKind::TyParam
@@ -310,6 +313,7 @@ pub enum Res<Id = hir::HirId> {
     ///
     /// **Belongs to the type namespace.**
     PrimTy(hir::PrimTy),
+
     /// The `Self` type, optionally with the [`DefId`] of the trait it belongs to and
     /// optionally with the [`DefId`] of the item introducing the `Self` type alias.
     ///
@@ -357,7 +361,8 @@ pub enum Res<Id = hir::HirId> {
     /// const fn baz<T>() -> usize { 10 }
     /// ```
     /// We do however allow `Self` in repeat expression even if it is generic to not break code
-    /// which already works on stable while causing the `const_evaluatable_unchecked` future compat lint:
+    /// which already works on stable while causing the `const_evaluatable_unchecked` future compat
+    /// lint:
     /// ```
     /// fn foo<T>() {
     ///     let _bar = [1_u8; std::mem::size_of::<*mut T>()];
@@ -372,6 +377,7 @@ pub enum Res<Id = hir::HirId> {
         /// from mentioning generics (i.e. when used in an anonymous constant).
         alias_to: Option<(DefId, bool)>,
     },
+
     /// A tool attribute module; e.g., the `rustfmt` in `#[rustfmt::skip]`.
     ///
     /// **Belongs to the type namespace.**
@@ -385,6 +391,7 @@ pub enum Res<Id = hir::HirId> {
     ///
     /// *See also [`Res::SelfTy`].*
     SelfCtor(DefId),
+
     /// A local variable or function parameter.
     ///
     /// **Belongs to the value namespace.**
@@ -455,7 +462,7 @@ impl PartialRes {
 
 /// Different kinds of symbols can coexist even if they share the same textual name.
 /// Therefore, they each have a separate universe (known as a "namespace").
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub enum Namespace {
     /// The type namespace includes `struct`s, `enum`s, `union`s, `trait`s, and `mod`s
     /// (and, by extension, crates).
@@ -564,15 +571,11 @@ impl NonMacroAttrKind {
             NonMacroAttrKind::DeriveHelper | NonMacroAttrKind::DeriveHelperCompat => {
                 "derive helper attribute"
             }
-            NonMacroAttrKind::Registered => "explicitly registered attribute",
         }
     }
 
     pub fn article(self) -> &'static str {
-        match self {
-            NonMacroAttrKind::Registered => "an",
-            _ => "a",
-        }
+        "a"
     }
 
     /// Users of some attributes cannot mark them as used, so they are considered always used.
@@ -581,7 +584,7 @@ impl NonMacroAttrKind {
             NonMacroAttrKind::Tool
             | NonMacroAttrKind::DeriveHelper
             | NonMacroAttrKind::DeriveHelperCompat => true,
-            NonMacroAttrKind::Builtin(..) | NonMacroAttrKind::Registered => false,
+            NonMacroAttrKind::Builtin(..) => false,
         }
     }
 }
diff --git a/compiler/rustc_hir/src/definitions.rs b/compiler/rustc_hir/src/definitions.rs
index c2c551e78..d85ac960f 100644
--- a/compiler/rustc_hir/src/definitions.rs
+++ b/compiler/rustc_hir/src/definitions.rs
@@ -15,7 +15,6 @@ use rustc_span::symbol::{kw, sym, Symbol};
 
 use std::fmt::{self, Write};
 use std::hash::Hash;
-use tracing::debug;
 
 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
diff --git a/compiler/rustc_hir/src/errors.rs b/compiler/rustc_hir/src/errors.rs
new file mode 100644
index 000000000..e593ed104
--- /dev/null
+++ b/compiler/rustc_hir/src/errors.rs
@@ -0,0 +1,10 @@
+use crate::LangItem;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable)]
+pub struct LangItemError(pub LangItem);
+
+impl ToString for LangItemError {
+    fn to_string(&self) -> String {
+        format!("requires `{}` lang_item", self.0.name())
+    }
+}
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 617433a98..a8436ea64 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -7,7 +7,7 @@ use crate::LangItem;
 use rustc_ast as ast;
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_ast::{Attribute, FloatTy, IntTy, Label, LitKind, TraitObjectSyntax, UintTy};
-pub use rustc_ast::{BorrowKind, ImplPolarity, IsAuto};
+pub use rustc_ast::{BindingAnnotation, BorrowKind, ByRef, ImplPolarity, IsAuto};
 pub use rustc_ast::{CaptureBy, Movability, Mutability};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -139,11 +139,10 @@ impl LifetimeName {
         match self {
             LifetimeName::ImplicitObjectLifetimeDefault | LifetimeName::Infer => true,
 
-            // It might seem surprising that `Fresh` counts as
-            // *not* elided -- but this is because, as far as the code
-            // in the compiler is concerned -- `Fresh` variants act
-            // equivalently to "some fresh name". They correspond to
-            // early-bound regions on an impl, in other words.
+            // It might seem surprising that `Fresh` counts as not *elided*
+            // -- but this is because, as far as the code in the compiler is
+            // concerned -- `Fresh` variants act equivalently to "some fresh name".
+            // They correspond to early-bound regions on an impl, in other words.
             LifetimeName::Error | LifetimeName::Param(..) | LifetimeName::Static => false,
         }
     }
@@ -202,13 +201,8 @@ impl Path<'_> {
 pub struct PathSegment<'hir> {
     /// The identifier portion of this path segment.
     pub ident: Ident,
-    // `id` and `res` are optional. We currently only use these in save-analysis,
-    // any path segments without these will not have save-analysis info and
-    // therefore will not have 'jump to def' in IDEs, but otherwise will not be
-    // affected. (In general, we don't bother to get the defs for synthesized
-    // segments, only for segments which have come from the AST).
-    pub hir_id: Option<HirId>,
-    pub res: Option<Res>,
+    pub hir_id: HirId,
+    pub res: Res,
 
     /// Type/lifetime parameters attached to this path. They come in
     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
@@ -226,12 +220,12 @@ pub struct PathSegment<'hir> {
 
 impl<'hir> PathSegment<'hir> {
     /// Converts an identifier to the corresponding segment.
-    pub fn from_ident(ident: Ident) -> PathSegment<'hir> {
-        PathSegment { ident, hir_id: None, res: None, infer_args: true, args: None }
+    pub fn new(ident: Ident, hir_id: HirId, res: Res) -> PathSegment<'hir> {
+        PathSegment { ident, hir_id, res, infer_args: true, args: None }
     }
 
     pub fn invalid() -> Self {
-        Self::from_ident(Ident::empty())
+        Self::new(Ident::empty(), HirId::INVALID, Res::Err)
     }
 
     pub fn args(&self) -> &GenericArgs<'hir> {
@@ -264,8 +258,8 @@ impl InferArg {
 
 #[derive(Debug, HashStable_Generic)]
 pub enum GenericArg<'hir> {
-    Lifetime(Lifetime),
-    Type(Ty<'hir>),
+    Lifetime(&'hir Lifetime),
+    Type(&'hir Ty<'hir>),
     Const(ConstArg),
     Infer(InferArg),
 }
@@ -280,7 +274,7 @@ impl GenericArg<'_> {
         }
     }
 
-    pub fn id(&self) -> HirId {
+    pub fn hir_id(&self) -> HirId {
         match self {
             GenericArg::Lifetime(l) => l.hir_id,
             GenericArg::Type(t) => t.hir_id,
@@ -305,9 +299,9 @@ impl GenericArg<'_> {
     pub fn to_ord(&self) -> ast::ParamKindOrd {
         match self {
             GenericArg::Lifetime(_) => ast::ParamKindOrd::Lifetime,
-            GenericArg::Type(_) => ast::ParamKindOrd::Type,
-            GenericArg::Const(_) => ast::ParamKindOrd::Const,
-            GenericArg::Infer(_) => ast::ParamKindOrd::Infer,
+            GenericArg::Type(_) | GenericArg::Const(_) | GenericArg::Infer(_) => {
+                ast::ParamKindOrd::TypeOrConst
+            }
         }
     }
 
@@ -435,7 +429,7 @@ pub enum GenericBound<'hir> {
     Trait(PolyTraitRef<'hir>, TraitBoundModifier),
     // FIXME(davidtwco): Introduce `PolyTraitRef::LangItem`
     LangItemTrait(LangItem, Span, HirId, &'hir GenericArgs<'hir>),
-    Outlives(Lifetime),
+    Outlives(&'hir Lifetime),
 }
 
 impl GenericBound<'_> {
@@ -581,8 +575,7 @@ impl<'hir> Generics<'hir> {
         if self.has_where_clause_predicates {
             self.predicates
                 .iter()
-                .filter(|p| p.in_where_clause())
-                .last()
+                .rfind(|&p| p.in_where_clause())
                 .map_or(end, |p| p.span())
                 .shrink_to_hi()
                 .to(end)
@@ -761,7 +754,7 @@ impl<'hir> WhereBoundPredicate<'hir> {
 pub struct WhereRegionPredicate<'hir> {
     pub span: Span,
     pub in_where_clause: bool,
-    pub lifetime: Lifetime,
+    pub lifetime: &'hir Lifetime,
     pub bounds: GenericBounds<'hir>,
 }
 
@@ -778,7 +771,6 @@ impl<'hir> WhereRegionPredicate<'hir> {
 /// An equality predicate (e.g., `T = int`); currently unsupported.
 #[derive(Debug, HashStable_Generic)]
 pub struct WhereEqPredicate<'hir> {
-    pub hir_id: HirId,
     pub span: Span,
     pub lhs_ty: &'hir Ty<'hir>,
     pub rhs_ty: &'hir Ty<'hir>,
@@ -841,7 +833,16 @@ impl<'tcx> OwnerNodes<'tcx> {
 impl fmt::Debug for OwnerNodes<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("OwnerNodes")
+            // Do not print all the pointers to all the nodes, as it would be unreadable.
             .field("node", &self.nodes[ItemLocalId::from_u32(0)])
+            .field(
+                "parents",
+                &self
+                    .nodes
+                    .iter_enumerated()
+                    .map(|(id, parented_node)| (id, parented_node.as_ref().map(|node| node.parent)))
+                    .collect::<Vec<_>>(),
+            )
             .field("bodies", &self.bodies)
             .field("local_id_to_def_id", &self.local_id_to_def_id)
             .field("hash_without_bodies", &self.hash_without_bodies)
@@ -1050,30 +1051,6 @@ pub struct PatField<'hir> {
     pub span: Span,
 }
 
-/// Explicit binding annotations given in the HIR for a binding. Note
-/// that this is not the final binding *mode* that we infer after type
-/// inference.
-#[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
-pub enum BindingAnnotation {
-    /// No binding annotation given: this means that the final binding mode
-    /// will depend on whether we have skipped through a `&` reference
-    /// when matching. For example, the `x` in `Some(x)` will have binding
-    /// mode `None`; if you do `let Some(x) = &Some(22)`, it will
-    /// ultimately be inferred to be by-reference.
-    ///
-    /// Note that implicit reference skipping is not implemented yet (#42640).
-    Unannotated,
-
-    /// Annotated with `mut x` -- could be either ref or not, similar to `None`.
-    Mutable,
-
-    /// Annotated as `ref`, like `ref x`
-    Ref,
-
-    /// Annotated as `ref mut x`.
-    RefMut,
-}
-
 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
 pub enum RangeEnd {
     Included,
@@ -1089,6 +1066,35 @@ impl fmt::Display for RangeEnd {
     }
 }
 
+// Equivalent to `Option<usize>`. That type takes up 16 bytes on 64-bit, but
+// this type only takes up 4 bytes, at the cost of being restricted to a
+// maximum value of `u32::MAX - 1`. In practice, this is more than enough.
+#[derive(Clone, Copy, PartialEq, Eq, Hash, HashStable_Generic)]
+pub struct DotDotPos(u32);
+
+impl DotDotPos {
+    // Panics if n >= u32::MAX.
+    pub fn new(n: Option<usize>) -> Self {
+        match n {
+            Some(n) => {
+                assert!(n < u32::MAX as usize);
+                Self(n as u32)
+            }
+            None => Self(u32::MAX),
+        }
+    }
+
+    pub fn as_opt_usize(&self) -> Option<usize> {
+        if self.0 == u32::MAX { None } else { Some(self.0 as usize) }
+    }
+}
+
+impl fmt::Debug for DotDotPos {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.as_opt_usize().fmt(f)
+    }
+}
+
 #[derive(Debug, HashStable_Generic)]
 pub enum PatKind<'hir> {
     /// Represents a wildcard pattern (i.e., `_`).
@@ -1105,9 +1111,9 @@ pub enum PatKind<'hir> {
     Struct(QPath<'hir>, &'hir [PatField<'hir>], bool),
 
     /// A tuple struct/variant pattern `Variant(x, y, .., z)`.
-    /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
+    /// If the `..` pattern fragment is present, then `DotDotPos` denotes its position.
     /// `0 <= position <= subpats.len()`
-    TupleStruct(QPath<'hir>, &'hir [Pat<'hir>], Option<usize>),
+    TupleStruct(QPath<'hir>, &'hir [Pat<'hir>], DotDotPos),
 
     /// An or-pattern `A | B | C`.
     /// Invariant: `pats.len() >= 2`.
@@ -1119,7 +1125,7 @@ pub enum PatKind<'hir> {
     /// A tuple pattern (e.g., `(a, b)`).
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`
-    Tuple(&'hir [Pat<'hir>], Option<usize>),
+    Tuple(&'hir [Pat<'hir>], DotDotPos),
 
     /// A `box` pattern.
     Box(&'hir Pat<'hir>),
@@ -1322,7 +1328,7 @@ pub enum StmtKind<'hir> {
     Semi(&'hir Expr<'hir>),
 }
 
-/// Represents a `let` statement (i.e., `let <pat>:<ty> = <expr>;`).
+/// Represents a `let` statement (i.e., `let <pat>:<ty> = <init>;`).
 #[derive(Debug, HashStable_Generic)]
 pub struct Local<'hir> {
     pub pat: &'hir Pat<'hir>,
@@ -1439,7 +1445,7 @@ pub struct BodyId {
 #[derive(Debug, HashStable_Generic)]
 pub struct Body<'hir> {
     pub params: &'hir [Param<'hir>],
-    pub value: Expr<'hir>,
+    pub value: &'hir Expr<'hir>,
     pub generator_kind: Option<GeneratorKind>,
 }
 
@@ -1626,7 +1632,7 @@ pub struct AnonConst {
 }
 
 /// An expression.
-#[derive(Debug)]
+#[derive(Debug, HashStable_Generic)]
 pub struct Expr<'hir> {
     pub hir_id: HirId,
     pub kind: ExprKind<'hir>,
@@ -1882,11 +1888,11 @@ pub enum ExprKind<'hir> {
     ///
     /// The `PathSegment` represents the method name and its generic arguments
     /// (within the angle brackets).
-    /// The first element of the `&[Expr]` is the expression that evaluates
+    /// The `&Expr` is the expression that evaluates
     /// to the object on which the method is being called on (the receiver),
-    /// and the remaining elements are the rest of the arguments.
+    /// and the `&[Expr]` is the rest of the arguments.
     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
-    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d], span)`.
+    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, x, [a, b, c, d], span)`.
     /// The final `Span` represents the span of the function and arguments
     /// (e.g. `foo::<Bar, Baz>(a, b, c, d)` in `x.foo::<Bar, Baz>(a, b, c, d)`
     ///
@@ -1894,7 +1900,7 @@ pub enum ExprKind<'hir> {
     /// the `hir_id` of the `MethodCall` node itself.
     ///
     /// [`type_dependent_def_id`]: ../../rustc_middle/ty/struct.TypeckResults.html#method.type_dependent_def_id
-    MethodCall(&'hir PathSegment<'hir>, &'hir [Expr<'hir>], Span),
+    MethodCall(&'hir PathSegment<'hir>, &'hir Expr<'hir>, &'hir [Expr<'hir>], Span),
     /// A tuple (e.g., `(a, b, c, d)`).
     Tup(&'hir [Expr<'hir>]),
     /// A binary operation (e.g., `a + b`, `a * b`).
@@ -2380,7 +2386,7 @@ impl TypeBinding<'_> {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable_Generic)]
 pub struct Ty<'hir> {
     pub hir_id: HirId,
     pub kind: TyKind<'hir>,
@@ -2402,6 +2408,14 @@ impl<'hir> Ty<'hir> {
             _ => None,
         }
     }
+
+    pub fn peel_refs(&self) -> &Self {
+        let mut final_ty = self;
+        while let TyKind::Rptr(_, MutTy { ty, .. }) = &final_ty.kind {
+            final_ty = &ty;
+        }
+        final_ty
+    }
 }
 
 /// Not represented directly in the AST; referred to by name through a `ty_path`.
@@ -2506,6 +2520,7 @@ pub struct OpaqueTy<'hir> {
     pub generics: &'hir Generics<'hir>,
     pub bounds: GenericBounds<'hir>,
     pub origin: OpaqueTyOrigin,
+    pub in_trait: bool,
 }
 
 /// From whence the opaque type came.
@@ -2529,7 +2544,7 @@ pub enum TyKind<'hir> {
     /// A raw pointer (i.e., `*const T` or `*mut T`).
     Ptr(MutTy<'hir>),
     /// A reference (i.e., `&'a T` or `&'a mut T`).
-    Rptr(Lifetime, MutTy<'hir>),
+    Rptr(&'hir Lifetime, MutTy<'hir>),
     /// A bare function (e.g., `fn(usize) -> bool`).
     BareFn(&'hir BareFnTy<'hir>),
     /// The never type (`!`).
@@ -2545,10 +2560,12 @@ pub enum TyKind<'hir> {
     ///
     /// The generic argument list contains the lifetimes (and in the future
     /// possibly parameters) that are actually bound on the `impl Trait`.
-    OpaqueDef(ItemId, &'hir [GenericArg<'hir>]),
+    ///
+    /// The last parameter specifies whether this opaque appears in a trait definition.
+    OpaqueDef(ItemId, &'hir [GenericArg<'hir>], bool),
     /// A trait object type `Bound1 + Bound2 + Bound3`
     /// where `Bound` is a trait or a lifetime.
-    TraitObject(&'hir [PolyTraitRef<'hir>], Lifetime, TraitObjectSyntax),
+    TraitObject(&'hir [PolyTraitRef<'hir>], &'hir Lifetime, TraitObjectSyntax),
     /// Unused for now.
     Typeof(AnonConst),
     /// `TyKind::Infer` means the type should be inferred instead of it having been
@@ -2562,23 +2579,23 @@ pub enum TyKind<'hir> {
 pub enum InlineAsmOperand<'hir> {
     In {
         reg: InlineAsmRegOrRegClass,
-        expr: Expr<'hir>,
+        expr: &'hir Expr<'hir>,
     },
     Out {
         reg: InlineAsmRegOrRegClass,
         late: bool,
-        expr: Option<Expr<'hir>>,
+        expr: Option<&'hir Expr<'hir>>,
     },
     InOut {
         reg: InlineAsmRegOrRegClass,
         late: bool,
-        expr: Expr<'hir>,
+        expr: &'hir Expr<'hir>,
     },
     SplitInOut {
         reg: InlineAsmRegOrRegClass,
         late: bool,
-        in_expr: Expr<'hir>,
-        out_expr: Option<Expr<'hir>>,
+        in_expr: &'hir Expr<'hir>,
+        out_expr: Option<&'hir Expr<'hir>>,
     },
     Const {
         anon_const: AnonConst,
@@ -2643,7 +2660,7 @@ pub struct FnDecl<'hir> {
 }
 
 /// Represents what type of implicit self a function has, if any.
-#[derive(Copy, Clone, Encodable, Decodable, Debug, HashStable_Generic)]
+#[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum ImplicitSelfKind {
     /// Represents a `fn x(self);`.
     Imm,
@@ -2992,7 +3009,7 @@ pub enum ItemKind<'hir> {
     /// A MBE macro definition (`macro_rules!` or `macro`).
     Macro(ast::MacroDef, MacroKind),
     /// A module.
-    Mod(Mod<'hir>),
+    Mod(&'hir Mod<'hir>),
     /// An external module, e.g. `extern { .. }`.
     ForeignMod { abi: Abi, items: &'hir [ForeignItemRef] },
     /// Module-level inline assembly (from `global_asm!`).
@@ -3217,7 +3234,7 @@ impl<'hir> OwnerNode<'hir> {
         }
     }
 
-    pub fn fn_decl(&self) -> Option<&FnDecl<'hir>> {
+    pub fn fn_decl(self) -> Option<&'hir FnDecl<'hir>> {
         match self {
             OwnerNode::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
             | OwnerNode::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
@@ -3332,12 +3349,14 @@ pub enum Node<'hir> {
     Field(&'hir FieldDef<'hir>),
     AnonConst(&'hir AnonConst),
     Expr(&'hir Expr<'hir>),
+    ExprField(&'hir ExprField<'hir>),
     Stmt(&'hir Stmt<'hir>),
     PathSegment(&'hir PathSegment<'hir>),
     Ty(&'hir Ty<'hir>),
     TypeBinding(&'hir TypeBinding<'hir>),
     TraitRef(&'hir TraitRef<'hir>),
     Pat(&'hir Pat<'hir>),
+    PatField(&'hir PatField<'hir>),
     Arm(&'hir Arm<'hir>),
     Block(&'hir Block<'hir>),
     Local(&'hir Local<'hir>),
@@ -3388,6 +3407,8 @@ impl<'hir> Node<'hir> {
             | Node::Block(..)
             | Node::Ctor(..)
             | Node::Pat(..)
+            | Node::PatField(..)
+            | Node::ExprField(..)
             | Node::Arm(..)
             | Node::Local(..)
             | Node::Crate(..)
@@ -3397,19 +3418,20 @@ impl<'hir> Node<'hir> {
         }
     }
 
-    pub fn fn_decl(&self) -> Option<&'hir FnDecl<'hir>> {
+    pub fn fn_decl(self) -> Option<&'hir FnDecl<'hir>> {
         match self {
             Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
             | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
             | Node::Item(Item { kind: ItemKind::Fn(fn_sig, _, _), .. }) => Some(fn_sig.decl),
-            Node::ForeignItem(ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
+            Node::Expr(Expr { kind: ExprKind::Closure(Closure { fn_decl, .. }), .. })
+            | Node::ForeignItem(ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
                 Some(fn_decl)
             }
             _ => None,
         }
     }
 
-    pub fn fn_sig(&self) -> Option<&'hir FnSig<'hir>> {
+    pub fn fn_sig(self) -> Option<&'hir FnSig<'hir>> {
         match self {
             Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
             | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
@@ -3491,16 +3513,37 @@ impl<'hir> Node<'hir> {
 mod size_asserts {
     use super::*;
     // These are in alphabetical order, which is easy to maintain.
-    rustc_data_structures::static_assert_size!(Block<'static>, 48);
-    rustc_data_structures::static_assert_size!(Expr<'static>, 56);
-    rustc_data_structures::static_assert_size!(ForeignItem<'static>, 72);
-    rustc_data_structures::static_assert_size!(GenericBound<'_>, 48);
-    rustc_data_structures::static_assert_size!(Generics<'static>, 56);
-    rustc_data_structures::static_assert_size!(ImplItem<'static>, 88);
-    rustc_data_structures::static_assert_size!(Impl<'static>, 80);
-    rustc_data_structures::static_assert_size!(Item<'static>, 80);
-    rustc_data_structures::static_assert_size!(Pat<'static>, 88);
-    rustc_data_structures::static_assert_size!(QPath<'static>, 24);
-    rustc_data_structures::static_assert_size!(TraitItem<'static>, 96);
-    rustc_data_structures::static_assert_size!(Ty<'static>, 72);
+    static_assert_size!(Block<'_>, 48);
+    static_assert_size!(Body<'_>, 32);
+    static_assert_size!(Expr<'_>, 64);
+    static_assert_size!(ExprKind<'_>, 48);
+    static_assert_size!(FnDecl<'_>, 40);
+    static_assert_size!(ForeignItem<'_>, 72);
+    static_assert_size!(ForeignItemKind<'_>, 40);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(GenericArg<'_>, 24);
+    static_assert_size!(GenericBound<'_>, 48);
+    static_assert_size!(Generics<'_>, 56);
+    static_assert_size!(Impl<'_>, 80);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(ImplItem<'_>, 80);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(ImplItemKind<'_>, 32);
+    static_assert_size!(Item<'_>, 80);
+    static_assert_size!(ItemKind<'_>, 48);
+    static_assert_size!(Local<'_>, 64);
+    static_assert_size!(Param<'_>, 32);
+    static_assert_size!(Pat<'_>, 72);
+    static_assert_size!(PatKind<'_>, 48);
+    static_assert_size!(Path<'_>, 48);
+    static_assert_size!(PathSegment<'_>, 56);
+    static_assert_size!(QPath<'_>, 24);
+    static_assert_size!(Stmt<'_>, 32);
+    static_assert_size!(StmtKind<'_>, 16);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(TraitItem<'_>, 88);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(TraitItemKind<'_>, 48);
+    static_assert_size!(Ty<'_>, 48);
+    static_assert_size!(TyKind<'_>, 32);
 }
diff --git a/compiler/rustc_hir/src/hir_id.rs b/compiler/rustc_hir/src/hir_id.rs
index 346ac9e96..84b0740c7 100644
--- a/compiler/rustc_hir/src/hir_id.rs
+++ b/compiler/rustc_hir/src/hir_id.rs
@@ -20,6 +20,9 @@ pub struct HirId {
 }
 
 impl HirId {
+    /// Signal local id which should never be used.
+    pub const INVALID: HirId = HirId { owner: CRATE_DEF_ID, local_id: ItemLocalId::INVALID };
+
     #[inline]
     pub fn expect_owner(self) -> LocalDefId {
         assert_eq!(self.local_id.index(), 0);
@@ -64,8 +67,13 @@ impl PartialOrd for HirId {
     }
 }
 
-rustc_data_structures::define_id_collections!(HirIdMap, HirIdSet, HirId);
-rustc_data_structures::define_id_collections!(ItemLocalMap, ItemLocalSet, ItemLocalId);
+rustc_data_structures::define_stable_id_collections!(HirIdMap, HirIdSet, HirIdMapEntry, HirId);
+rustc_data_structures::define_id_collections!(
+    ItemLocalMap,
+    ItemLocalSet,
+    ItemLocalMapEntry,
+    ItemLocalId
+);
 
 rustc_index::newtype_index! {
     /// An `ItemLocalId` uniquely identifies something within a given "item-like";
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index e676acebe..8f5f314ec 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -298,7 +298,7 @@ pub trait Visitor<'v>: Sized {
     fn visit_id(&mut self, _hir_id: HirId) {
         // Nothing to do.
     }
-    fn visit_name(&mut self, _span: Span, _name: Symbol) {
+    fn visit_name(&mut self, _name: Symbol) {
         // Nothing to do.
     }
     fn visit_ident(&mut self, ident: Ident) {
@@ -325,6 +325,9 @@ pub trait Visitor<'v>: Sized {
     fn visit_pat(&mut self, p: &'v Pat<'v>) {
         walk_pat(self, p)
     }
+    fn visit_pat_field(&mut self, f: &'v PatField<'v>) {
+        walk_pat_field(self, f)
+    }
     fn visit_array_length(&mut self, len: &'v ArrayLen) {
         walk_array_len(self, len)
     }
@@ -337,6 +340,9 @@ pub trait Visitor<'v>: Sized {
     fn visit_let_expr(&mut self, lex: &'v Let<'v>) {
         walk_let_expr(self, lex)
     }
+    fn visit_expr_field(&mut self, field: &'v ExprField<'v>) {
+        walk_expr_field(self, field)
+    }
     fn visit_ty(&mut self, t: &'v Ty<'v>) {
         walk_ty(self, t)
     }
@@ -355,8 +361,8 @@ pub trait Visitor<'v>: Sized {
     fn visit_fn_decl(&mut self, fd: &'v FnDecl<'v>) {
         walk_fn_decl(self, fd)
     }
-    fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v FnDecl<'v>, b: BodyId, s: Span, id: HirId) {
-        walk_fn(self, fk, fd, b, s, id)
+    fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v FnDecl<'v>, b: BodyId, _: Span, id: HirId) {
+        walk_fn(self, fk, fd, b, id)
     }
     fn visit_use(&mut self, path: &'v Path<'v>, hir_id: HirId) {
         walk_use(self, path, hir_id)
@@ -382,33 +388,20 @@ pub trait Visitor<'v>: Sized {
     fn visit_param_bound(&mut self, bounds: &'v GenericBound<'v>) {
         walk_param_bound(self, bounds)
     }
-    fn visit_poly_trait_ref(&mut self, t: &'v PolyTraitRef<'v>, m: TraitBoundModifier) {
-        walk_poly_trait_ref(self, t, m)
-    }
-    fn visit_variant_data(
-        &mut self,
-        s: &'v VariantData<'v>,
-        _: Symbol,
-        _: &'v Generics<'v>,
-        _parent_id: HirId,
-        _: Span,
-    ) {
+    fn visit_poly_trait_ref(&mut self, t: &'v PolyTraitRef<'v>) {
+        walk_poly_trait_ref(self, t)
+    }
+    fn visit_variant_data(&mut self, s: &'v VariantData<'v>) {
         walk_struct_def(self, s)
     }
     fn visit_field_def(&mut self, s: &'v FieldDef<'v>) {
         walk_field_def(self, s)
     }
-    fn visit_enum_def(
-        &mut self,
-        enum_definition: &'v EnumDef<'v>,
-        generics: &'v Generics<'v>,
-        item_id: HirId,
-        _: Span,
-    ) {
-        walk_enum_def(self, enum_definition, generics, item_id)
+    fn visit_enum_def(&mut self, enum_definition: &'v EnumDef<'v>, item_id: HirId) {
+        walk_enum_def(self, enum_definition, item_id)
     }
-    fn visit_variant(&mut self, v: &'v Variant<'v>, g: &'v Generics<'v>, item_id: HirId) {
-        walk_variant(self, v, g, item_id)
+    fn visit_variant(&mut self, v: &'v Variant<'v>) {
+        walk_variant(self, v)
     }
     fn visit_label(&mut self, label: &'v Label) {
         walk_label(self, label)
@@ -427,17 +420,18 @@ pub trait Visitor<'v>: Sized {
     fn visit_lifetime(&mut self, lifetime: &'v Lifetime) {
         walk_lifetime(self, lifetime)
     }
-    fn visit_qpath(&mut self, qpath: &'v QPath<'v>, id: HirId, span: Span) {
-        walk_qpath(self, qpath, id, span)
+    // The span is that of the surrounding type/pattern/expr/whatever.
+    fn visit_qpath(&mut self, qpath: &'v QPath<'v>, id: HirId, _span: Span) {
+        walk_qpath(self, qpath, id)
     }
     fn visit_path(&mut self, path: &'v Path<'v>, _id: HirId) {
         walk_path(self, path)
     }
-    fn visit_path_segment(&mut self, path_span: Span, path_segment: &'v PathSegment<'v>) {
-        walk_path_segment(self, path_span, path_segment)
+    fn visit_path_segment(&mut self, path_segment: &'v PathSegment<'v>) {
+        walk_path_segment(self, path_segment)
     }
-    fn visit_generic_args(&mut self, path_span: Span, generic_args: &'v GenericArgs<'v>) {
-        walk_generic_args(self, path_span, generic_args)
+    fn visit_generic_args(&mut self, generic_args: &'v GenericArgs<'v>) {
+        walk_generic_args(self, generic_args)
     }
     fn visit_assoc_type_binding(&mut self, type_binding: &'v TypeBinding<'v>) {
         walk_assoc_type_binding(self, type_binding)
@@ -479,7 +473,7 @@ pub fn walk_local<'v, V: Visitor<'v>>(visitor: &mut V, local: &'v Local<'v>) {
 }
 
 pub fn walk_ident<'v, V: Visitor<'v>>(visitor: &mut V, ident: Ident) {
-    visitor.visit_name(ident.span, ident.name);
+    visitor.visit_name(ident.name);
 }
 
 pub fn walk_label<'v, V: Visitor<'v>>(visitor: &mut V, label: &'v Label) {
@@ -501,11 +495,7 @@ pub fn walk_lifetime<'v, V: Visitor<'v>>(visitor: &mut V, lifetime: &'v Lifetime
     }
 }
 
-pub fn walk_poly_trait_ref<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    trait_ref: &'v PolyTraitRef<'v>,
-    _modifier: TraitBoundModifier,
-) {
+pub fn walk_poly_trait_ref<'v, V: Visitor<'v>>(visitor: &mut V, trait_ref: &'v PolyTraitRef<'v>) {
     walk_list!(visitor, visit_generic_param, trait_ref.bound_generic_params);
     visitor.visit_trait_ref(&trait_ref.trait_ref);
 }
@@ -526,7 +516,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) {
         ItemKind::ExternCrate(orig_name) => {
             visitor.visit_id(item.hir_id());
             if let Some(orig_name) = orig_name {
-                visitor.visit_name(item.span, orig_name);
+                visitor.visit_name(orig_name);
             }
         }
         ItemKind::Use(ref path, _) => {
@@ -572,7 +562,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) {
         ItemKind::Enum(ref enum_definition, ref generics) => {
             visitor.visit_generics(generics);
             // `visit_enum_def()` takes care of visiting the `Item`'s `HirId`.
-            visitor.visit_enum_def(enum_definition, generics, item.hir_id(), item.span)
+            visitor.visit_enum_def(enum_definition, item.hir_id())
         }
         ItemKind::Impl(Impl {
             unsafety: _,
@@ -595,13 +585,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) {
         | ItemKind::Union(ref struct_definition, ref generics) => {
             visitor.visit_generics(generics);
             visitor.visit_id(item.hir_id());
-            visitor.visit_variant_data(
-                struct_definition,
-                item.ident.name,
-                generics,
-                item.hir_id(),
-                item.span,
-            );
+            visitor.visit_variant_data(struct_definition);
         }
         ItemKind::Trait(.., ref generics, bounds, trait_item_refs) => {
             visitor.visit_id(item.hir_id());
@@ -649,28 +633,16 @@ pub fn walk_use<'v, V: Visitor<'v>>(visitor: &mut V, path: &'v Path<'v>, hir_id:
 pub fn walk_enum_def<'v, V: Visitor<'v>>(
     visitor: &mut V,
     enum_definition: &'v EnumDef<'v>,
-    generics: &'v Generics<'v>,
     item_id: HirId,
 ) {
     visitor.visit_id(item_id);
-    walk_list!(visitor, visit_variant, enum_definition.variants, generics, item_id);
+    walk_list!(visitor, visit_variant, enum_definition.variants);
 }
 
-pub fn walk_variant<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    variant: &'v Variant<'v>,
-    generics: &'v Generics<'v>,
-    parent_item_id: HirId,
-) {
+pub fn walk_variant<'v, V: Visitor<'v>>(visitor: &mut V, variant: &'v Variant<'v>) {
     visitor.visit_ident(variant.ident);
     visitor.visit_id(variant.id);
-    visitor.visit_variant_data(
-        &variant.data,
-        variant.ident.name,
-        generics,
-        parent_item_id,
-        variant.span,
-    );
+    visitor.visit_variant_data(&variant.data);
     walk_list!(visitor, visit_anon_const, &variant.disr_expr);
 }
 
@@ -695,7 +667,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) {
         TyKind::Path(ref qpath) => {
             visitor.visit_qpath(qpath, typ.hir_id, typ.span);
         }
-        TyKind::OpaqueDef(item_id, lifetimes) => {
+        TyKind::OpaqueDef(item_id, lifetimes, _in_trait) => {
             visitor.visit_nested_item(item_id);
             walk_list!(visitor, visit_generic_arg, lifetimes);
         }
@@ -705,7 +677,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) {
         }
         TyKind::TraitObject(bounds, ref lifetime, _syntax) => {
             for bound in bounds {
-                visitor.visit_poly_trait_ref(bound, TraitBoundModifier::None);
+                visitor.visit_poly_trait_ref(bound);
             }
             visitor.visit_lifetime(lifetime);
         }
@@ -718,12 +690,7 @@ pub fn walk_inf<'v, V: Visitor<'v>>(visitor: &mut V, inf: &'v InferArg) {
     visitor.visit_id(inf.hir_id);
 }
 
-pub fn walk_qpath<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    qpath: &'v QPath<'v>,
-    id: HirId,
-    span: Span,
-) {
+pub fn walk_qpath<'v, V: Visitor<'v>>(visitor: &mut V, qpath: &'v QPath<'v>, id: HirId) {
     match *qpath {
         QPath::Resolved(ref maybe_qself, ref path) => {
             walk_list!(visitor, visit_ty, maybe_qself);
@@ -731,7 +698,7 @@ pub fn walk_qpath<'v, V: Visitor<'v>>(
         }
         QPath::TypeRelative(ref qself, ref segment) => {
             visitor.visit_ty(qself);
-            visitor.visit_path_segment(span, segment);
+            visitor.visit_path_segment(segment);
         }
         QPath::LangItem(..) => {}
     }
@@ -739,27 +706,19 @@ pub fn walk_qpath<'v, V: Visitor<'v>>(
 
 pub fn walk_path<'v, V: Visitor<'v>>(visitor: &mut V, path: &'v Path<'v>) {
     for segment in path.segments {
-        visitor.visit_path_segment(path.span, segment);
+        visitor.visit_path_segment(segment);
     }
 }
 
-pub fn walk_path_segment<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    path_span: Span,
-    segment: &'v PathSegment<'v>,
-) {
+pub fn walk_path_segment<'v, V: Visitor<'v>>(visitor: &mut V, segment: &'v PathSegment<'v>) {
     visitor.visit_ident(segment.ident);
-    walk_list!(visitor, visit_id, segment.hir_id);
+    visitor.visit_id(segment.hir_id);
     if let Some(ref args) = segment.args {
-        visitor.visit_generic_args(path_span, args);
+        visitor.visit_generic_args(args);
     }
 }
 
-pub fn walk_generic_args<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    _path_span: Span,
-    generic_args: &'v GenericArgs<'v>,
-) {
+pub fn walk_generic_args<'v, V: Visitor<'v>>(visitor: &mut V, generic_args: &'v GenericArgs<'v>) {
     walk_list!(visitor, visit_generic_arg, generic_args.args);
     walk_list!(visitor, visit_assoc_type_binding, generic_args.bindings);
 }
@@ -770,7 +729,7 @@ pub fn walk_assoc_type_binding<'v, V: Visitor<'v>>(
 ) {
     visitor.visit_id(type_binding.hir_id);
     visitor.visit_ident(type_binding.ident);
-    visitor.visit_generic_args(type_binding.span, type_binding.gen_args);
+    visitor.visit_generic_args(type_binding.gen_args);
     match type_binding.kind {
         TypeBindingKind::Equality { ref term } => match term {
             Term::Ty(ref ty) => visitor.visit_ty(ty),
@@ -792,11 +751,7 @@ pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat<'v>) {
         }
         PatKind::Struct(ref qpath, fields, _) => {
             visitor.visit_qpath(qpath, pattern.hir_id, pattern.span);
-            for field in fields {
-                visitor.visit_id(field.hir_id);
-                visitor.visit_ident(field.ident);
-                visitor.visit_pat(&field.pat)
-            }
+            walk_list!(visitor, visit_pat_field, fields);
         }
         PatKind::Or(pats) => walk_list!(visitor, visit_pat, pats),
         PatKind::Tuple(tuple_elements, _) => {
@@ -823,6 +778,12 @@ pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat<'v>) {
     }
 }
 
+pub fn walk_pat_field<'v, V: Visitor<'v>>(visitor: &mut V, field: &'v PatField<'v>) {
+    visitor.visit_id(field.hir_id);
+    visitor.visit_ident(field.ident);
+    visitor.visit_pat(&field.pat)
+}
+
 pub fn walk_foreign_item<'v, V: Visitor<'v>>(visitor: &mut V, foreign_item: &'v ForeignItem<'v>) {
     visitor.visit_id(foreign_item.hir_id());
     visitor.visit_ident(foreign_item.ident);
@@ -842,12 +803,12 @@ pub fn walk_foreign_item<'v, V: Visitor<'v>>(visitor: &mut V, foreign_item: &'v
 
 pub fn walk_param_bound<'v, V: Visitor<'v>>(visitor: &mut V, bound: &'v GenericBound<'v>) {
     match *bound {
-        GenericBound::Trait(ref typ, modifier) => {
-            visitor.visit_poly_trait_ref(typ, modifier);
+        GenericBound::Trait(ref typ, _modifier) => {
+            visitor.visit_poly_trait_ref(typ);
         }
-        GenericBound::LangItemTrait(_, span, hir_id, args) => {
+        GenericBound::LangItemTrait(_, _span, hir_id, args) => {
             visitor.visit_id(hir_id);
-            visitor.visit_generic_args(span, args);
+            visitor.visit_generic_args(args);
         }
         GenericBound::Outlives(ref lifetime) => visitor.visit_lifetime(lifetime),
     }
@@ -899,10 +860,7 @@ pub fn walk_where_predicate<'v, V: Visitor<'v>>(
             visitor.visit_lifetime(lifetime);
             walk_list!(visitor, visit_param_bound, bounds);
         }
-        WherePredicate::EqPredicate(WhereEqPredicate {
-            hir_id, ref lhs_ty, ref rhs_ty, ..
-        }) => {
-            visitor.visit_id(hir_id);
+        WherePredicate::EqPredicate(WhereEqPredicate { ref lhs_ty, ref rhs_ty, .. }) => {
             visitor.visit_ty(lhs_ty);
             visitor.visit_ty(rhs_ty);
         }
@@ -936,7 +894,6 @@ pub fn walk_fn<'v, V: Visitor<'v>>(
     function_kind: FnKind<'v>,
     function_declaration: &'v FnDecl<'v>,
     body_id: BodyId,
-    _span: Span,
     id: HirId,
 ) {
     visitor.visit_id(id);
@@ -1090,6 +1047,12 @@ pub fn walk_let_expr<'v, V: Visitor<'v>>(visitor: &mut V, let_expr: &'v Let<'v>)
     walk_list!(visitor, visit_ty, let_expr.ty);
 }
 
+pub fn walk_expr_field<'v, V: Visitor<'v>>(visitor: &mut V, field: &'v ExprField<'v>) {
+    visitor.visit_id(field.hir_id);
+    visitor.visit_ident(field.ident);
+    visitor.visit_expr(&field.expr)
+}
+
 pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>) {
     visitor.visit_id(expression.hir_id);
     match expression.kind {
@@ -1104,11 +1067,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
         }
         ExprKind::Struct(ref qpath, fields, ref optional_base) => {
             visitor.visit_qpath(qpath, expression.hir_id, expression.span);
-            for field in fields {
-                visitor.visit_id(field.hir_id);
-                visitor.visit_ident(field.ident);
-                visitor.visit_expr(&field.expr)
-            }
+            walk_list!(visitor, visit_expr_field, fields);
             walk_list!(visitor, visit_expr, optional_base);
         }
         ExprKind::Tup(subexpressions) => {
@@ -1118,8 +1077,9 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
             visitor.visit_expr(callee_expression);
             walk_list!(visitor, visit_expr, arguments);
         }
-        ExprKind::MethodCall(ref segment, arguments, _) => {
-            visitor.visit_path_segment(expression.span, segment);
+        ExprKind::MethodCall(ref segment, receiver, arguments, _) => {
+            visitor.visit_path_segment(segment);
+            visitor.visit_expr(receiver);
             walk_list!(visitor, visit_expr, arguments);
         }
         ExprKind::Binary(_, ref left_expression, ref right_expression) => {
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index c337be12a..ca615a491 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -8,6 +8,7 @@
 //! * Functions called by the compiler itself.
 
 use crate::def_id::DefId;
+use crate::errors::LangItemError;
 use crate::{MethodKind, Target};
 
 use rustc_ast as ast;
@@ -115,9 +116,9 @@ macro_rules! language_item_table {
 
             /// Requires that a given `LangItem` was bound and returns the corresponding `DefId`.
             /// If it wasn't bound, e.g. due to a missing `#[lang = "<it.name()>"]`,
-            /// returns an error message as a string.
-            pub fn require(&self, it: LangItem) -> Result<DefId, String> {
-                self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name()))
+            /// returns an error encapsulating the `LangItem`.
+            pub fn require(&self, it: LangItem) -> Result<DefId, LangItemError> {
+                self.items[it as usize].ok_or_else(|| LangItemError(it))
             }
 
             /// Returns the [`DefId`]s of all lang items in a group.
@@ -192,7 +193,8 @@ language_item_table! {
     DispatchFromDyn,         sym::dispatch_from_dyn,   dispatch_from_dyn_trait,    Target::Trait,          GenericRequirement::Minimum(1);
 
     // language items relating to transmutability
-    TransmuteTrait,          sym::transmute_trait,     transmute_trait,            Target::Trait,          GenericRequirement::Exact(6);
+    TransmuteOpts,           sym::transmute_opts,      transmute_opts,             Target::Struct,         GenericRequirement::Exact(0);
+    TransmuteTrait,          sym::transmute_trait,     transmute_trait,            Target::Trait,          GenericRequirement::Exact(3);
 
     Add(Op),                 sym::add,                 add_trait,                  Target::Trait,          GenericRequirement::Exact(1);
     Sub(Op),                 sym::sub,                 sub_trait,                  Target::Trait,          GenericRequirement::Exact(1);
@@ -236,7 +238,6 @@ language_item_table! {
     Future,                  sym::future_trait,        future_trait,               Target::Trait,          GenericRequirement::Exact(0);
     GeneratorState,          sym::generator_state,     gen_state,                  Target::Enum,           GenericRequirement::None;
     Generator,               sym::generator,           gen_trait,                  Target::Trait,          GenericRequirement::Minimum(1);
-    GeneratorReturn,         sym::generator_return,    generator_return,           Target::AssocTy,        GenericRequirement::None;
     Unpin,                   sym::unpin,               unpin_trait,                Target::Trait,          GenericRequirement::None;
     Pin,                     sym::pin,                 pin_type,                   Target::Struct,         GenericRequirement::None;
 
@@ -267,8 +268,6 @@ language_item_table! {
     DropInPlace,             sym::drop_in_place,       drop_in_place_fn,           Target::Fn,             GenericRequirement::Minimum(1);
     Oom,                     sym::oom,                 oom,                        Target::Fn,             GenericRequirement::None;
     AllocLayout,             sym::alloc_layout,        alloc_layout,               Target::Struct,         GenericRequirement::None;
-    ConstEvalSelect,         sym::const_eval_select,   const_eval_select,          Target::Fn,             GenericRequirement::Exact(4);
-    ConstConstEvalSelect,    sym::const_eval_select_ct,const_eval_select_ct,       Target::Fn,             GenericRequirement::Exact(4);
 
     Start,                   sym::start,               start_fn,                   Target::Fn,             GenericRequirement::Exact(1);
 
@@ -290,6 +289,8 @@ language_item_table! {
 
     Try,                     sym::Try,                 try_trait,                  Target::Trait,          GenericRequirement::None;
 
+    Tuple,                   sym::tuple_trait,         tuple_trait,                Target::Trait,          GenericRequirement::Exact(0);
+
     SliceLen,                sym::slice_len_fn,        slice_len_fn,               Target::Method(MethodKind::Inherent), GenericRequirement::None;
 
     // Language items from AST lowering
diff --git a/compiler/rustc_hir/src/lib.rs b/compiler/rustc_hir/src/lib.rs
index 0f9e6fa7b..946da9265 100644
--- a/compiler/rustc_hir/src/lib.rs
+++ b/compiler/rustc_hir/src/lib.rs
@@ -5,17 +5,22 @@
 #![feature(associated_type_defaults)]
 #![feature(closure_track_caller)]
 #![feature(const_btree_new)]
-#![feature(let_else)]
+#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(once_cell)]
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![recursion_limit = "256"]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 
 #[macro_use]
 extern crate rustc_macros;
 
 #[macro_use]
+extern crate tracing;
+
+#[macro_use]
 extern crate rustc_data_structures;
 
 extern crate self as rustc_hir;
@@ -25,6 +30,7 @@ pub mod def;
 pub mod def_path_hash_map;
 pub mod definitions;
 pub mod diagnostic_items;
+pub mod errors;
 pub use rustc_span::def_id;
 mod hir;
 pub mod hir_id;
diff --git a/compiler/rustc_hir/src/pat_util.rs b/compiler/rustc_hir/src/pat_util.rs
index 93112199b..0c1819bb0 100644
--- a/compiler/rustc_hir/src/pat_util.rs
+++ b/compiler/rustc_hir/src/pat_util.rs
@@ -1,6 +1,6 @@
 use crate::def::{CtorOf, DefKind, Res};
 use crate::def_id::DefId;
-use crate::hir::{self, HirId, PatKind};
+use crate::hir::{self, BindingAnnotation, ByRef, HirId, PatKind};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::Ident;
@@ -35,7 +35,7 @@ pub trait EnumerateAndAdjustIterator {
     fn enumerate_and_adjust(
         self,
         expected_len: usize,
-        gap_pos: Option<usize>,
+        gap_pos: hir::DotDotPos,
     ) -> EnumerateAndAdjust<Self>
     where
         Self: Sized;
@@ -45,7 +45,7 @@ impl<T: ExactSizeIterator> EnumerateAndAdjustIterator for T {
     fn enumerate_and_adjust(
         self,
         expected_len: usize,
-        gap_pos: Option<usize>,
+        gap_pos: hir::DotDotPos,
     ) -> EnumerateAndAdjust<Self>
     where
         Self: Sized,
@@ -53,7 +53,7 @@ impl<T: ExactSizeIterator> EnumerateAndAdjustIterator for T {
         let actual_len = self.len();
         EnumerateAndAdjust {
             enumerate: self.enumerate(),
-            gap_pos: gap_pos.unwrap_or(expected_len),
+            gap_pos: gap_pos.as_opt_usize().unwrap_or(expected_len),
             gap_len: expected_len - actual_len,
         }
     }
@@ -93,12 +93,7 @@ impl hir::Pat<'_> {
 
     pub fn simple_ident(&self) -> Option<Ident> {
         match self.kind {
-            PatKind::Binding(
-                hir::BindingAnnotation::Unannotated | hir::BindingAnnotation::Mutable,
-                _,
-                ident,
-                None,
-            ) => Some(ident),
+            PatKind::Binding(BindingAnnotation(ByRef::No, _), _, ident, None) => Some(ident),
             _ => None,
         }
     }
@@ -135,11 +130,11 @@ impl hir::Pat<'_> {
     pub fn contains_explicit_ref_binding(&self) -> Option<hir::Mutability> {
         let mut result = None;
         self.each_binding(|annotation, _, _, _| match annotation {
-            hir::BindingAnnotation::Ref => match result {
+            hir::BindingAnnotation::REF => match result {
                 None | Some(hir::Mutability::Not) => result = Some(hir::Mutability::Not),
                 _ => {}
             },
-            hir::BindingAnnotation::RefMut => result = Some(hir::Mutability::Mut),
+            hir::BindingAnnotation::REF_MUT => result = Some(hir::Mutability::Mut),
             _ => {}
         });
         result
diff --git a/compiler/rustc_hir/src/stable_hash_impls.rs b/compiler/rustc_hir/src/stable_hash_impls.rs
index 8ccd59e8e..5b9c42686 100644
--- a/compiler/rustc_hir/src/stable_hash_impls.rs
+++ b/compiler/rustc_hir/src/stable_hash_impls.rs
@@ -1,8 +1,7 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 
 use crate::hir::{
-    AttributeMap, BodyId, Crate, Expr, ForeignItemId, ImplItemId, ItemId, OwnerNodes, TraitItemId,
-    Ty,
+    AttributeMap, BodyId, Crate, ForeignItemId, ImplItemId, ItemId, OwnerNodes, TraitItemId,
 };
 use crate::hir_id::{HirId, ItemLocalId};
 use rustc_span::def_id::DefPathHash;
@@ -14,8 +13,6 @@ pub trait HashStableContext:
     rustc_ast::HashStableContext + rustc_target::HashStableContext
 {
     fn hash_body_id(&mut self, _: BodyId, hasher: &mut StableHasher);
-    fn hash_hir_expr(&mut self, _: &Expr<'_>, hasher: &mut StableHasher);
-    fn hash_hir_ty(&mut self, _: &Ty<'_>, hasher: &mut StableHasher);
 }
 
 impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for HirId {
@@ -96,18 +93,6 @@ impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for BodyId {
 // want to pick up on a reference changing its target, so we hash the NodeIds
 // in "DefPath Mode".
 
-impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for Expr<'_> {
-    fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
-        hcx.hash_hir_expr(self, hasher)
-    }
-}
-
-impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for Ty<'_> {
-    fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
-        hcx.hash_hir_ty(self, hasher)
-    }
-}
-
 impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerNodes<'tcx> {
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         // We ignore the `nodes` and `bodies` fields since these refer to information included in
diff --git a/compiler/rustc_hir/src/target.rs b/compiler/rustc_hir/src/target.rs
index 6236dea10..5917d5e34 100644
--- a/compiler/rustc_hir/src/target.rs
+++ b/compiler/rustc_hir/src/target.rs
@@ -36,6 +36,7 @@ pub enum Target {
     GlobalAsm,
     TyAlias,
     OpaqueTy,
+    ImplTraitPlaceholder,
     Enum,
     Variant,
     Struct,
@@ -56,6 +57,8 @@ pub enum Target {
     GenericParam(GenericParamKind),
     MacroDef,
     Param,
+    PatField,
+    ExprField,
 }
 
 impl Display for Target {
@@ -77,7 +80,13 @@ impl Target {
             ItemKind::ForeignMod { .. } => Target::ForeignMod,
             ItemKind::GlobalAsm(..) => Target::GlobalAsm,
             ItemKind::TyAlias(..) => Target::TyAlias,
-            ItemKind::OpaqueTy(..) => Target::OpaqueTy,
+            ItemKind::OpaqueTy(ref opaque) => {
+                if opaque.in_trait {
+                    Target::ImplTraitPlaceholder
+                } else {
+                    Target::OpaqueTy
+                }
+            }
             ItemKind::Enum(..) => Target::Enum,
             ItemKind::Struct(..) => Target::Struct,
             ItemKind::Union(..) => Target::Union,
@@ -101,6 +110,7 @@ impl Target {
             DefKind::GlobalAsm => Target::GlobalAsm,
             DefKind::TyAlias => Target::TyAlias,
             DefKind::OpaqueTy => Target::OpaqueTy,
+            DefKind::ImplTraitPlaceholder => Target::ImplTraitPlaceholder,
             DefKind::Enum => Target::Enum,
             DefKind::Struct => Target::Struct,
             DefKind::Union => Target::Union,
@@ -155,6 +165,7 @@ impl Target {
             Target::GlobalAsm => "global asm",
             Target::TyAlias => "type alias",
             Target::OpaqueTy => "opaque type",
+            Target::ImplTraitPlaceholder => "opaque type in trait",
             Target::Enum => "enum",
             Target::Variant => "enum variant",
             Target::Struct => "struct",
@@ -183,6 +194,8 @@ impl Target {
             },
             Target::MacroDef => "macro def",
             Target::Param => "function param",
+            Target::PatField => "pattern field",
+            Target::ExprField => "struct field",
         }
     }
 }
diff --git a/compiler/rustc_hir/src/weak_lang_items.rs b/compiler/rustc_hir/src/weak_lang_items.rs
index b6a85c047..da9c9c121 100644
--- a/compiler/rustc_hir/src/weak_lang_items.rs
+++ b/compiler/rustc_hir/src/weak_lang_items.rs
@@ -18,6 +18,12 @@ pub static WEAK_ITEMS_REFS: LazyLock<FxIndexMap<Symbol, LangItem>> = LazyLock::n
     map
 });
 
+pub static WEAK_ITEMS_SYMBOLS: LazyLock<FxIndexMap<LangItem, Symbol>> = LazyLock::new(|| {
+    let mut map = FxIndexMap::default();
+    $(map.insert(LangItem::$item, sym::$sym);)*
+    map
+});
+
 pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol>
 {
     lang_items::extract(attrs).and_then(|(name, _)| {