Apply nits, uplift ExistentialPredicate too

9 files changed, 100 insertions, 82 deletions

diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
index 297cfe7027e..37d4d4ec355 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
@@ -7,7 +7,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_lint_defs::builtin::UNUSED_ASSOCIATED_TYPE_BOUNDS;
 use rustc_middle::ty::fold::BottomUpFolder;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{self, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::ty::{DynKind, ToPredicate};
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::traits::error_reporting::report_object_safety_error;
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 70fb937cae7..f9d1a77c3d9 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -26,6 +26,7 @@ use crate::traits::solve;
 use crate::traits::solve::{
     ExternalConstraints, ExternalConstraintsData, PredefinedOpaques, PredefinedOpaquesData,
 };
+use crate::ty::predicate::ExistentialPredicateStableCmpExt as _;
 use crate::ty::{
     self, AdtDef, AdtDefData, AdtKind, Binder, Clause, Clauses, Const, ConstData,
     GenericParamDefKind, ImplPolarity, List, ListWithCachedTypeInfo, ParamConst, ParamTy, Pattern,
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 28baa334840..2b0d8796968 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -96,13 +96,13 @@ pub use self::list::{List, ListWithCachedTypeInfo};
 pub use self::parameterized::ParameterizedOverTcx;
 pub use self::pattern::{Pattern, PatternKind};
 pub use self::predicate::{
-    Clause, ClauseKind, CoercePredicate, ExistentialPredicate, ExistentialProjection,
-    ExistentialTraitRef, NormalizesTo, OutlivesPredicate, PolyCoercePredicate,
-    PolyExistentialPredicate, PolyExistentialProjection, PolyExistentialTraitRef,
-    PolyProjectionPredicate, PolyRegionOutlivesPredicate, PolySubtypePredicate, PolyTraitPredicate,
-    PolyTraitRef, PolyTypeOutlivesPredicate, Predicate, PredicateKind, ProjectionPredicate,
-    RegionOutlivesPredicate, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitPredicate,
-    TraitRef, TypeOutlivesPredicate,
+    Clause, ClauseKind, CoercePredicate, ExistentialPredicate, ExistentialPredicateStableCmpExt,
+    ExistentialProjection, ExistentialTraitRef, NormalizesTo, OutlivesPredicate,
+    PolyCoercePredicate, PolyExistentialPredicate, PolyExistentialProjection,
+    PolyExistentialTraitRef, PolyProjectionPredicate, PolyRegionOutlivesPredicate,
+    PolySubtypePredicate, PolyTraitPredicate, PolyTraitRef, PolyTypeOutlivesPredicate, Predicate,
+    PredicateKind, ProjectionPredicate, RegionOutlivesPredicate, SubtypePredicate, ToPolyTraitRef,
+    ToPredicate, TraitPredicate, TraitRef, TypeOutlivesPredicate,
 };
 pub use self::region::{
     BoundRegion, BoundRegionKind, BoundRegionKind::*, EarlyParamRegion, LateParamRegion, Region,
diff --git a/compiler/rustc_middle/src/ty/predicate.rs b/compiler/rustc_middle/src/ty/predicate.rs
index dbbb86cb28e..c1de23b2498 100644
--- a/compiler/rustc_middle/src/ty/predicate.rs
+++ b/compiler/rustc_middle/src/ty/predicate.rs
@@ -1,34 +1,28 @@
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::intern::Interned;
 use rustc_hir::def_id::DefId;
-use rustc_macros::{HashStable, Lift, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
-use rustc_type_ir::ClauseKind as IrClauseKind;
-use rustc_type_ir::CoercePredicate as IrCoercePredicate;
-use rustc_type_ir::ExistentialProjection as IrExistentialProjection;
-use rustc_type_ir::ExistentialTraitRef as IrExistentialTraitRef;
-use rustc_type_ir::NormalizesTo as IrNormalizesTo;
-use rustc_type_ir::PredicateKind as IrPredicateKind;
-use rustc_type_ir::ProjectionPredicate as IrProjectionPredicate;
-use rustc_type_ir::SubtypePredicate as IrSubtypePredicate;
-use rustc_type_ir::TraitPredicate as IrTraitPredicate;
-use rustc_type_ir::TraitRef as IrTraitRef;
+use rustc_macros::{
+    extension, HashStable, Lift, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable,
+};
+use rustc_type_ir as ir;
 use std::cmp::Ordering;
 
 use crate::ty::{
-    self, Binder, DebruijnIndex, DebugWithInfcx, EarlyBinder, PredicatePolarity, Term, Ty, TyCtxt,
-    TypeFlags, WithCachedTypeInfo,
+    self, Binder, DebruijnIndex, EarlyBinder, PredicatePolarity, Term, Ty, TyCtxt, TypeFlags,
+    WithCachedTypeInfo,
 };
 
-pub type TraitRef<'tcx> = IrTraitRef<TyCtxt<'tcx>>;
-pub type ProjectionPredicate<'tcx> = IrProjectionPredicate<TyCtxt<'tcx>>;
-pub type ExistentialTraitRef<'tcx> = IrExistentialTraitRef<TyCtxt<'tcx>>;
-pub type ExistentialProjection<'tcx> = IrExistentialProjection<TyCtxt<'tcx>>;
-pub type TraitPredicate<'tcx> = IrTraitPredicate<TyCtxt<'tcx>>;
-pub type ClauseKind<'tcx> = IrClauseKind<TyCtxt<'tcx>>;
-pub type PredicateKind<'tcx> = IrPredicateKind<TyCtxt<'tcx>>;
-pub type NormalizesTo<'tcx> = IrNormalizesTo<TyCtxt<'tcx>>;
-pub type CoercePredicate<'tcx> = IrCoercePredicate<TyCtxt<'tcx>>;
-pub type SubtypePredicate<'tcx> = IrSubtypePredicate<TyCtxt<'tcx>>;
+pub type TraitRef<'tcx> = ir::TraitRef<TyCtxt<'tcx>>;
+pub type ProjectionPredicate<'tcx> = ir::ProjectionPredicate<TyCtxt<'tcx>>;
+pub type ExistentialPredicate<'tcx> = ir::ExistentialPredicate<TyCtxt<'tcx>>;
+pub type ExistentialTraitRef<'tcx> = ir::ExistentialTraitRef<TyCtxt<'tcx>>;
+pub type ExistentialProjection<'tcx> = ir::ExistentialProjection<TyCtxt<'tcx>>;
+pub type TraitPredicate<'tcx> = ir::TraitPredicate<TyCtxt<'tcx>>;
+pub type ClauseKind<'tcx> = ir::ClauseKind<TyCtxt<'tcx>>;
+pub type PredicateKind<'tcx> = ir::PredicateKind<TyCtxt<'tcx>>;
+pub type NormalizesTo<'tcx> = ir::NormalizesTo<TyCtxt<'tcx>>;
+pub type CoercePredicate<'tcx> = ir::CoercePredicate<TyCtxt<'tcx>>;
+pub type SubtypePredicate<'tcx> = ir::SubtypePredicate<TyCtxt<'tcx>>;
 
 /// A statement that can be proven by a trait solver. This includes things that may
 /// show up in where clauses, such as trait predicates and projection predicates,
@@ -207,43 +201,25 @@ impl<'tcx> Clause<'tcx> {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
-#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
-pub enum ExistentialPredicate<'tcx> {
-    /// E.g., `Iterator`.
-    Trait(ExistentialTraitRef<'tcx>),
-    /// E.g., `Iterator::Item = T`.
-    Projection(ExistentialProjection<'tcx>),
-    /// E.g., `Send`.
-    AutoTrait(DefId),
-}
-
-impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for ExistentialPredicate<'tcx> {
-    fn fmt<Infcx: rustc_type_ir::InferCtxtLike<Interner = TyCtxt<'tcx>>>(
-        this: rustc_type_ir::WithInfcx<'_, Infcx, &Self>,
-        f: &mut std::fmt::Formatter<'_>,
-    ) -> std::fmt::Result {
-        std::fmt::Debug::fmt(&this.data, f)
-    }
-}
-
+#[extension(pub trait ExistentialPredicateStableCmpExt<'tcx>)]
 impl<'tcx> ExistentialPredicate<'tcx> {
     /// Compares via an ordering that will not change if modules are reordered or other changes are
     /// made to the tree. In particular, this ordering is preserved across incremental compilations.
-    pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
-        use self::ExistentialPredicate::*;
+    fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
         match (*self, *other) {
-            (Trait(_), Trait(_)) => Ordering::Equal,
-            (Projection(ref a), Projection(ref b)) => {
+            (ExistentialPredicate::Trait(_), ExistentialPredicate::Trait(_)) => Ordering::Equal,
+            (ExistentialPredicate::Projection(ref a), ExistentialPredicate::Projection(ref b)) => {
                 tcx.def_path_hash(a.def_id).cmp(&tcx.def_path_hash(b.def_id))
             }
-            (AutoTrait(ref a), AutoTrait(ref b)) => {
+            (ExistentialPredicate::AutoTrait(ref a), ExistentialPredicate::AutoTrait(ref b)) => {
                 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
             }
-            (Trait(_), _) => Ordering::Less,
-            (Projection(_), Trait(_)) => Ordering::Greater,
-            (Projection(_), _) => Ordering::Less,
-            (AutoTrait(_), _) => Ordering::Greater,
+            (ExistentialPredicate::Trait(_), _) => Ordering::Less,
+            (ExistentialPredicate::Projection(_), ExistentialPredicate::Trait(_)) => {
+                Ordering::Greater
+            }
+            (ExistentialPredicate::Projection(_), _) => Ordering::Less,
+            (ExistentialPredicate::AutoTrait(_), _) => Ordering::Greater,
         }
     }
 }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 6137a5fd48a..be9525a083c 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -3088,6 +3088,16 @@ define_print! {
         }
     }
 
+    ty::ExistentialPredicate<'tcx> {
+        match *self {
+            ty::ExistentialPredicate::Trait(x) => p!(print(x)),
+            ty::ExistentialPredicate::Projection(x) => p!(print(x)),
+            ty::ExistentialPredicate::AutoTrait(def_id) => {
+                p!(print_def_path(def_id, &[]));
+            }
+        }
+    }
+
     ty::ExistentialTraitRef<'tcx> {
         // Use a type that can't appear in defaults of type parameters.
         let dummy_self = Ty::new_fresh(cx.tcx(), 0);
@@ -3132,16 +3142,6 @@ define_print_and_forward_display! {
         p!("{{", comma_sep(self.iter()), "}}")
     }
 
-    ty::ExistentialPredicate<'tcx> {
-        match *self {
-            ty::ExistentialPredicate::Trait(x) => p!(print(x)),
-            ty::ExistentialPredicate::Projection(x) => p!(print(x)),
-            ty::ExistentialPredicate::AutoTrait(def_id) => {
-                p!(print_def_path(def_id, &[]));
-            }
-        }
-    }
-
     ty::FnSig<'tcx> {
         p!(write("{}", self.unsafety.prefix_str()));
 
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index 7063ef07201..417edda10ca 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -5,8 +5,10 @@
 //! subtyping, type equality, etc.
 
 use crate::ty::error::{ExpectedFound, TypeError};
-use crate::ty::{self, Expr, ImplSubject, Term, TermKind, Ty, TyCtxt, TypeFoldable};
-use crate::ty::{GenericArg, GenericArgKind, GenericArgsRef};
+use crate::ty::{
+    self, ExistentialPredicate, ExistentialPredicateStableCmpExt as _, Expr, GenericArg,
+    GenericArgKind, GenericArgsRef, ImplSubject, Term, TermKind, Ty, TyCtxt, TypeFoldable,
+};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
@@ -702,14 +704,21 @@ impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
         }
 
         let v = iter::zip(a_v, b_v).map(|(ep_a, ep_b)| {
-            use crate::ty::ExistentialPredicate::*;
             match (ep_a.skip_binder(), ep_b.skip_binder()) {
-                (Trait(a), Trait(b)) => Ok(ep_a
-                    .rebind(Trait(relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder()))),
-                (Projection(a), Projection(b)) => Ok(ep_a.rebind(Projection(
-                    relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder(),
-                ))),
-                (AutoTrait(a), AutoTrait(b)) if a == b => Ok(ep_a.rebind(AutoTrait(a))),
+                (ExistentialPredicate::Trait(a), ExistentialPredicate::Trait(b)) => Ok(ep_a
+                    .rebind(ExistentialPredicate::Trait(
+                        relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder(),
+                    ))),
+                (ExistentialPredicate::Projection(a), ExistentialPredicate::Projection(b)) => {
+                    Ok(ep_a.rebind(ExistentialPredicate::Projection(
+                        relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder(),
+                    )))
+                }
+                (ExistentialPredicate::AutoTrait(a), ExistentialPredicate::AutoTrait(b))
+                    if a == b =>
+                {
+                    Ok(ep_a.rebind(ExistentialPredicate::AutoTrait(a)))
+                }
                 _ => Err(TypeError::ExistentialMismatch(expected_found(a, b))),
             }
         });
diff --git a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
index 7141c6c9bb0..21433cfdb61 100644
--- a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
+++ b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
@@ -8,7 +8,8 @@ use rustc_hir::LangItem;
 use rustc_middle::bug;
 use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::{
-    self, Instance, IntTy, List, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, UintTy,
+    self, ExistentialPredicateStableCmpExt as _, Instance, IntTy, List, Ty, TyCtxt, TypeFoldable,
+    TypeVisitableExt, UintTy,
 };
 use rustc_span::sym;
 use rustc_trait_selection::traits;
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 5cb61dff831..75e43bc8f5d 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -18,7 +18,8 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{
-    self, EarlyBinder, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor,
+    self, EarlyBinder, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeSuperVisitable,
+    TypeVisitable, TypeVisitor,
 };
 use rustc_middle::ty::{GenericArg, GenericArgs};
 use rustc_middle::ty::{ToPredicate, TypeVisitableExt};
diff --git a/compiler/rustc_type_ir/src/predicate.rs b/compiler/rustc_type_ir/src/predicate.rs
index b16227ee10f..b2510cb01df 100644
--- a/compiler/rustc_type_ir/src/predicate.rs
+++ b/compiler/rustc_type_ir/src/predicate.rs
@@ -5,7 +5,7 @@ use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Gen
 
 use crate::inherent::*;
 use crate::visit::TypeVisitableExt as _;
-use crate::Interner;
+use crate::{DebugWithInfcx, Interner};
 
 /// A complete reference to a trait. These take numerous guises in syntax,
 /// but perhaps the most recognizable form is in a where-clause:
@@ -146,6 +146,36 @@ impl fmt::Display for PredicatePolarity {
     }
 }
 
+#[derive(derivative::Derivative)]
+#[derivative(
+    Clone(bound = ""),
+    Copy(bound = ""),
+    Hash(bound = ""),
+    PartialEq(bound = ""),
+    Eq(bound = ""),
+    Debug(bound = "")
+)]
+#[derive(TypeVisitable_Generic, TypeFoldable_Generic, Lift_Generic)]
+#[cfg_attr(feature = "nightly", derive(TyDecodable, TyEncodable, HashStable_NoContext))]
+pub enum ExistentialPredicate<I: Interner> {
+    /// E.g., `Iterator`.
+    Trait(ExistentialTraitRef<I>),
+    /// E.g., `Iterator::Item = T`.
+    Projection(ExistentialProjection<I>),
+    /// E.g., `Send`.
+    AutoTrait(I::DefId),
+}
+
+// FIXME: Implement this the right way after
+impl<I: Interner> DebugWithInfcx<I> for ExistentialPredicate<I> {
+    fn fmt<Infcx: rustc_type_ir::InferCtxtLike<Interner = I>>(
+        this: rustc_type_ir::WithInfcx<'_, Infcx, &Self>,
+        f: &mut fmt::Formatter<'_>,
+    ) -> fmt::Result {
+        fmt::Debug::fmt(&this.data, f)
+    }
+}
+
 /// An existential reference to a trait, where `Self` is erased.
 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
 /// ```ignore (illustrative)