1 files changed, 68 insertions, 20 deletions

diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 52b498ff7..2afcb5413 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/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};
 
@@ -58,6 +58,8 @@ pub type ClosureId = chalk_ir::ClosureId<Interner>;
 pub type OpaqueTyId = chalk_ir::OpaqueTyId<Interner>;
 pub type PlaceholderIndex = chalk_ir::PlaceholderIndex;
 
+pub type ChalkTraitId = chalk_ir::TraitId<Interner>;
+
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Lifetime {
     Parameter(LifetimeParamId),
@@ -70,6 +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.
@@ -81,7 +97,10 @@ pub struct ProjectionTy {
 
 impl ProjectionTy {
     pub fn trait_ref(&self, db: &dyn HirDatabase) -> TraitRef {
-        TraitRef { trait_: self.trait_(db), substs: self.substitution.clone() }
+        TraitRef {
+            trait_id: to_chalk_trait_id(self.trait_(db)),
+            substitution: self.substitution.clone(),
+        }
     }
 
     fn trait_(&self, db: &dyn HirDatabase) -> TraitId {
@@ -128,6 +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
@@ -493,23 +531,25 @@ impl<T: TypeWalk> TypeWalk for Binders<T> {
 }
 
 /// A trait with type parameters. This includes the `Self`, so this represents a concrete type implementing the trait.
-/// Name to be bikeshedded: TraitBound? TraitImplements?
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct TraitRef {
-    /// FIXME name?
-    pub trait_: TraitId,
-    pub substs: Substitution,
+    pub trait_id: ChalkTraitId,
+    pub substitution: Substitution,
 }
 
 impl TraitRef {
-    pub fn self_ty(&self) -> &Ty {
-        &self.substs[0]
+    pub fn self_type_parameter(&self) -> &Ty {
+        &self.substitution[0]
+    }
+
+    pub fn hir_trait_id(&self) -> TraitId {
+        from_chalk_trait_id(self.trait_id)
     }
 }
 
 impl TypeWalk for TraitRef {
     fn walk(&self, f: &mut impl FnMut(&Ty)) {
-        self.substs.walk(f);
+        self.substitution.walk(f);
     }
 
     fn walk_mut_binders(
@@ -517,7 +557,7 @@ impl TypeWalk for TraitRef {
         f: &mut impl FnMut(&mut Ty, DebruijnIndex),
         binders: DebruijnIndex,
     ) {
-        self.substs.walk_mut_binders(f, binders);
+        self.substitution.walk_mut_binders(f, binders);
     }
 }
 
@@ -528,7 +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,
@@ -546,8 +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,
         }
     }
 }
@@ -556,7 +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 => {}
         }
     }
@@ -568,9 +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 => {}
         }
     }
@@ -784,7 +824,7 @@ impl Ty {
 
     /// If this is a `dyn Trait`, returns that trait.
     pub fn dyn_trait(&self) -> Option<TraitId> {
-        self.dyn_trait_ref().map(|it| it.trait_)
+        self.dyn_trait_ref().map(|it| it.trait_id).map(from_chalk_trait_id)
     }
 
     fn builtin_deref(&self) -> Option<Ty> {
@@ -868,8 +908,8 @@ impl Ty {
                             // Parameters will be walked outside, and projection predicate is not used.
                             // So just provide the Future trait.
                             let impl_bound = GenericPredicate::Implemented(TraitRef {
-                                trait_: future_trait,
-                                substs: Substitution::empty(),
+                                trait_id: to_chalk_trait_id(future_trait),
+                                substitution: Substitution::empty(),
                             });
                             Some(vec![impl_bound])
                         } else {
@@ -1158,3 +1198,11 @@ pub fn to_placeholder_idx(db: &dyn HirDatabase, id: TypeParamId) -> PlaceholderI
         idx: salsa::InternKey::as_intern_id(&interned_id).as_usize(),
     }
 }
+
+pub fn to_chalk_trait_id(id: TraitId) -> ChalkTraitId {
+    chalk_ir::TraitId(salsa::InternKey::as_intern_id(&id))
+}
+
+pub fn from_chalk_trait_id(id: ChalkTraitId) -> TraitId {
+    salsa::InternKey::from_intern_id(id.0)
+}