Replace Projection variant in GenericPredicate with AliasEq

crates/hir/src/lib.rs

@@ -56,9 +56,9 @@ use hir_ty::{
     primitive::UintTy,
     to_assoc_type_id,
     traits::{FnTrait, Solution, SolutionVariables},
-    AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, DebruijnIndex, GenericPredicate,
-    InEnvironment, Interner, Obligation, ProjectionPredicate, ProjectionTy, Scalar, Substitution,
-    Ty, TyDefId, TyKind, TyVariableKind,
+    AliasEq, AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, DebruijnIndex,
+    GenericPredicate, InEnvironment, Interner, Obligation, ProjectionTy, Scalar, Substitution, Ty,
+    TyDefId, TyKind, TyVariableKind,
 };
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
@@ -1786,17 +1786,17 @@ impl Type {
             .push(self.ty.value.clone())
             .fill(args.iter().map(|t| t.ty.value.clone()))
             .build();
-        let predicate = ProjectionPredicate {
-            projection_ty: ProjectionTy {
-                associated_ty_id: to_assoc_type_id(alias.id),
-                substitution: subst,
-            },
-            ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner),
-        };
         let goal = Canonical {
             value: InEnvironment::new(
                 self.ty.environment.clone(),
-                Obligation::Projection(predicate),
+                Obligation::AliasEq(AliasEq {
+                    alias: AliasTy::Projection(ProjectionTy {
+                        associated_ty_id: to_assoc_type_id(alias.id),
+                        substitution: subst,
+                    }),
+                    ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
+                        .intern(&Interner),
+                }),
             ),
             kinds: Arc::new([TyVariableKind::General]),
         };

crates/hir_ty/src/autoderef.rs

@@ -15,7 +15,8 @@ use crate::{
     to_assoc_type_id, to_chalk_trait_id,
     traits::{InEnvironment, Solution},
     utils::generics,
-    BoundVar, Canonical, DebruijnIndex, Interner, Obligation, Substitution, TraitRef, Ty, TyKind,
+    AliasEq, AliasTy, BoundVar, Canonical, DebruijnIndex, Interner, Obligation, ProjectionTy,
+    Substitution, TraitRef, Ty, TyKind,
 };
 
 const AUTODEREF_RECURSION_LIMIT: usize = 10;
@@ -82,16 +83,16 @@ fn deref_by_trait(
     }
 
     // Now do the assoc type projection
-    let projection = super::traits::ProjectionPredicate {
-        ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, ty.value.kinds.len()))
-            .intern(&Interner),
-        projection_ty: super::ProjectionTy {
+    let projection = AliasEq {
+        alias: AliasTy::Projection(ProjectionTy {
             associated_ty_id: to_assoc_type_id(target),
             substitution: parameters,
-        },
+        }),
+        ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, ty.value.kinds.len()))
+            .intern(&Interner),
     };
 
-    let obligation = super::Obligation::Projection(projection);
+    let obligation = super::Obligation::AliasEq(projection);
 
     let in_env = InEnvironment { value: obligation, environment: ty.environment };
 

crates/hir_ty/src/display.rs

@@ -18,9 +18,9 @@ use hir_expand::name::Name;
 
 use crate::{
     db::HirDatabase, from_assoc_type_id, from_foreign_def_id, from_placeholder_idx, primitive,
-    to_assoc_type_id, traits::chalk::from_chalk, utils::generics, AdtId, AliasTy, CallableDefId,
-    CallableSig, GenericPredicate, ImplTraitId, Interner, Lifetime, Obligation, OpaqueTy,
-    ProjectionTy, Scalar, Substitution, TraitRef, Ty, TyKind,
+    to_assoc_type_id, traits::chalk::from_chalk, utils::generics, AdtId, AliasEq, AliasTy,
+    CallableDefId, CallableSig, GenericPredicate, ImplTraitId, Interner, Lifetime, Obligation,
+    OpaqueTy, ProjectionTy, Scalar, Substitution, TraitRef, Ty, TyKind,
 };
 
 pub struct HirFormatter<'a> {
@@ -268,6 +268,16 @@ impl HirDisplay for ProjectionTy {
     }
 }
 
+impl HirDisplay for OpaqueTy {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        self.substitution[0].hir_fmt(f)
+    }
+}
+
 impl HirDisplay for Ty {
     fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
@@ -700,12 +710,12 @@ fn write_bounds_like_dyn_trait(
                     }
                 }
             }
-            GenericPredicate::Projection(projection_pred) if is_fn_trait => {
+            GenericPredicate::AliasEq(alias_eq) if is_fn_trait => {
                 is_fn_trait = false;
                 write!(f, " -> ")?;
-                projection_pred.ty.hir_fmt(f)?;
+                alias_eq.ty.hir_fmt(f)?;
             }
-            GenericPredicate::Projection(projection_pred) => {
+            GenericPredicate::AliasEq(AliasEq { ty, alias }) => {
                 // in types in actual Rust, these will always come
                 // after the corresponding Implemented predicate
                 if angle_open {
@@ -714,11 +724,12 @@ fn write_bounds_like_dyn_trait(
                     write!(f, "<")?;
                     angle_open = true;
                 }
-                let type_alias = f.db.type_alias_data(from_assoc_type_id(
-                    projection_pred.projection_ty.associated_ty_id,
-                ));
-                write!(f, "{} = ", type_alias.name)?;
-                projection_pred.ty.hir_fmt(f)?;
+                if let AliasTy::Projection(proj) = alias {
+                    let type_alias =
+                        f.db.type_alias_data(from_assoc_type_id(proj.associated_ty_id));
+                    write!(f, "{} = ", type_alias.name)?;
+                }
+                ty.hir_fmt(f)?;
             }
             GenericPredicate::Error => {
                 if angle_open {
@@ -775,20 +786,20 @@ impl HirDisplay for GenericPredicate {
 
         match self {
             GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
-            GenericPredicate::Projection(projection_pred) => {
+            GenericPredicate::AliasEq(AliasEq {
+                alias: AliasTy::Projection(projection_ty),
+                ty,
+            }) => {
                 write!(f, "<")?;
-                projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
+                projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
                 write!(
                     f,
                     ">::{} = ",
-                    f.db.type_alias_data(from_assoc_type_id(
-                        projection_pred.projection_ty.associated_ty_id
-                    ))
-                    .name,
+                    f.db.type_alias_data(from_assoc_type_id(projection_ty.associated_ty_id)).name,
                 )?;
-                projection_pred.ty.hir_fmt(f)?;
+                ty.hir_fmt(f)?;
             }
-            GenericPredicate::Error => write!(f, "{{error}}")?,
+            GenericPredicate::AliasEq(_) | GenericPredicate::Error => write!(f, "{{error}}")?,
         }
         Ok(())
     }
@@ -815,11 +826,14 @@ impl HirDisplay for Obligation {
                 tr.hir_fmt(f)?;
                 write!(f, ")")
             }
-            Obligation::Projection(proj) => {
+            Obligation::AliasEq(AliasEq { alias, ty }) => {
                 write!(f, "Normalize(")?;
-                proj.projection_ty.hir_fmt(f)?;
+                match alias {
+                    AliasTy::Projection(projection_ty) => projection_ty.hir_fmt(f)?,
+                    AliasTy::Opaque(opaque) => opaque.hir_fmt(f)?,
+                }
                 write!(f, " => ")?;
-                proj.ty.hir_fmt(f)?;
+                ty.hir_fmt(f)?;
                 write!(f, ")")
             }
         }

crates/hir_ty/src/infer.rs

@@ -37,12 +37,12 @@ use stdx::impl_from;
 use syntax::SmolStr;
 
 use super::{
-    traits::{Guidance, Obligation, ProjectionPredicate, Solution},
+    traits::{Guidance, Obligation, Solution},
     InEnvironment, ProjectionTy, Substitution, TraitEnvironment, TraitRef, Ty, TypeWalk,
 };
 use crate::{
     db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode,
-    to_assoc_type_id, to_chalk_trait_id, AliasTy, Interner, TyKind,
+    to_assoc_type_id, to_chalk_trait_id, AliasEq, AliasTy, Interner, TyKind,
 };
 
 pub(crate) use unify::unify;
@@ -396,15 +396,15 @@ impl<'a> InferenceContext<'a> {
                     .build();
                 let trait_ref =
                     TraitRef { trait_id: to_chalk_trait_id(trait_), substitution: substs.clone() };
-                let projection = ProjectionPredicate {
-                    ty: ty.clone(),
-                    projection_ty: ProjectionTy {
+                let alias_eq = AliasEq {
+                    alias: AliasTy::Projection(ProjectionTy {
                         associated_ty_id: to_assoc_type_id(res_assoc_ty),
                         substitution: substs,
-                    },
+                    }),
+                    ty: ty.clone(),
                 };
                 self.obligations.push(Obligation::Trait(trait_ref));
-                self.obligations.push(Obligation::Projection(projection));
+                self.obligations.push(Obligation::AliasEq(alias_eq));
                 self.resolve_ty_as_possible(ty)
             }
             None => self.err_ty(),
@@ -429,8 +429,8 @@ impl<'a> InferenceContext<'a> {
 
     fn normalize_projection_ty(&mut self, proj_ty: ProjectionTy) -> Ty {
         let var = self.table.new_type_var();
-        let predicate = ProjectionPredicate { projection_ty: proj_ty, ty: var.clone() };
-        let obligation = Obligation::Projection(predicate);
+        let alias_eq = AliasEq { alias: AliasTy::Projection(proj_ty), ty: var.clone() };
+        let obligation = Obligation::AliasEq(alias_eq);
         self.obligations.push(obligation);
         var
     }

crates/hir_ty/src/infer/unify.rs

@@ -7,8 +7,8 @@ use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
 
 use super::{InferenceContext, Obligation};
 use crate::{
-    BoundVar, Canonical, DebruijnIndex, FnPointer, GenericPredicate, InEnvironment, InferenceVar,
-    Interner, Scalar, Substitution, Ty, TyKind, TypeWalk,
+    AliasEq, AliasTy, BoundVar, Canonical, DebruijnIndex, FnPointer, GenericPredicate,
+    InEnvironment, InferenceVar, Interner, Scalar, Substitution, Ty, TyKind, TypeWalk,
 };
 
 impl<'a> InferenceContext<'a> {
@@ -93,8 +93,8 @@ impl<'a, 'b> Canonicalizer<'a, 'b> {
             Obligation::Trait(tr) => {
                 Obligation::Trait(self.do_canonicalize(tr, DebruijnIndex::INNERMOST))
             }
-            Obligation::Projection(pr) => {
-                Obligation::Projection(self.do_canonicalize(pr, DebruijnIndex::INNERMOST))
+            Obligation::AliasEq(alias_eq) => {
+                Obligation::AliasEq(self.do_canonicalize(alias_eq, DebruijnIndex::INNERMOST))
             }
         };
         self.into_canonicalized(InEnvironment {
@@ -394,14 +394,25 @@ impl InferenceTable {
             {
                 self.unify_substs(&tr1.substitution, &tr2.substitution, depth + 1)
             }
-            (GenericPredicate::Projection(proj1), GenericPredicate::Projection(proj2))
-                if proj1.projection_ty.associated_ty_id == proj2.projection_ty.associated_ty_id =>
-            {
-                self.unify_substs(
-                    &proj1.projection_ty.substitution,
-                    &proj2.projection_ty.substitution,
-                    depth + 1,
-                ) && self.unify_inner(&proj1.ty, &proj2.ty, depth + 1)
+            (
+                GenericPredicate::AliasEq(AliasEq { alias: alias1, ty: ty1 }),
+                GenericPredicate::AliasEq(AliasEq { alias: alias2, ty: ty2 }),
+            ) => {
+                let (substitution1, substitution2) = match (alias1, alias2) {
+                    (AliasTy::Projection(projection_ty1), AliasTy::Projection(projection_ty2))
+                        if projection_ty1.associated_ty_id == projection_ty2.associated_ty_id =>
+                    {
+                        (&projection_ty1.substitution, &projection_ty2.substitution)
+                    }
+                    (AliasTy::Opaque(opaque1), AliasTy::Opaque(opaque2))
+                        if opaque1.opaque_ty_id == opaque2.opaque_ty_id =>
+                    {
+                        (&opaque1.substitution, &opaque2.substitution)
+                    }
+                    _ => return false,
+                };
+                self.unify_substs(&substitution1, &substitution2, depth + 1)
+                    && self.unify_inner(&ty1, &ty2, depth + 1)
             }
             _ => false,
         }

crates/hir_ty/src/lib.rs

@@ -45,7 +45,7 @@ pub use lower::{
     associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
     TyDefId, TyLoweringContext, ValueTyDefId,
 };
-pub use traits::{InEnvironment, Obligation, ProjectionPredicate, TraitEnvironment};
+pub use traits::{AliasEq, InEnvironment, Obligation, TraitEnvironment};
 
 pub use chalk_ir::{AdtId, BoundVar, DebruijnIndex, Mutability, Safety, Scalar, TyVariableKind};
 
@@ -72,6 +72,20 @@ pub struct OpaqueTy {
     pub substitution: Substitution,
 }
 
+impl TypeWalk for OpaqueTy {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        self.substitution.walk(f);
+    }
+
+    fn walk_mut_binders(
+        &mut self,
+        f: &mut impl FnMut(&mut Ty, DebruijnIndex),
+        binders: DebruijnIndex,
+    ) {
+        self.substitution.walk_mut_binders(f, binders);
+    }
+}
+
 /// A "projection" type corresponds to an (unnormalized)
 /// projection like `<P0 as Trait<P1..Pn>>::Foo`. Note that the
 /// trait and all its parameters are fully known.
@@ -133,6 +147,25 @@ pub enum AliasTy {
     Opaque(OpaqueTy),
 }
 
+impl TypeWalk for AliasTy {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        match self {
+            AliasTy::Projection(it) => it.walk(f),
+            AliasTy::Opaque(it) => it.walk(f),
+        }
+    }
+
+    fn walk_mut_binders(
+        &mut self,
+        f: &mut impl FnMut(&mut Ty, DebruijnIndex),
+        binders: DebruijnIndex,
+    ) {
+        match self {
+            AliasTy::Projection(it) => it.walk_mut_binders(f, binders),
+            AliasTy::Opaque(it) => it.walk_mut_binders(f, binders),
+        }
+    }
+}
 /// A type.
 ///
 /// See also the `TyKind` enum in rustc (librustc/ty/sty.rs), which represents
@@ -535,7 +568,7 @@ pub enum GenericPredicate {
     /// The given trait needs to be implemented for its type parameters.
     Implemented(TraitRef),
     /// An associated type bindings like in `Iterator<Item = T>`.
-    Projection(ProjectionPredicate),
+    AliasEq(AliasEq),
     /// We couldn't resolve the trait reference. (If some type parameters can't
     /// be resolved, they will just be Unknown).
     Error,
@@ -553,8 +586,10 @@ impl GenericPredicate {
     pub fn trait_ref(&self, db: &dyn HirDatabase) -> Option<TraitRef> {
         match self {
             GenericPredicate::Implemented(tr) => Some(tr.clone()),
-            GenericPredicate::Projection(proj) => Some(proj.projection_ty.trait_ref(db)),
-            GenericPredicate::Error => None,
+            GenericPredicate::AliasEq(AliasEq { alias: AliasTy::Projection(proj), .. }) => {
+                Some(proj.trait_ref(db))
+            }
+            GenericPredicate::AliasEq(_) | GenericPredicate::Error => None,
         }
     }
 }
@@ -563,7 +598,7 @@ impl TypeWalk for GenericPredicate {
     fn walk(&self, f: &mut impl FnMut(&Ty)) {
         match self {
             GenericPredicate::Implemented(trait_ref) => trait_ref.walk(f),
-            GenericPredicate::Projection(projection_pred) => projection_pred.walk(f),
+            GenericPredicate::AliasEq(alias_eq) => alias_eq.walk(f),
             GenericPredicate::Error => {}
         }
     }
@@ -575,9 +610,7 @@ impl TypeWalk for GenericPredicate {
     ) {
         match self {
             GenericPredicate::Implemented(trait_ref) => trait_ref.walk_mut_binders(f, binders),
-            GenericPredicate::Projection(projection_pred) => {
-                projection_pred.walk_mut_binders(f, binders)
-            }
+            GenericPredicate::AliasEq(alias_eq) => alias_eq.walk_mut_binders(f, binders),
             GenericPredicate::Error => {}
         }
     }