refactor: use `cast()` instead of interning `GenericArgData`

5 files changed, 34 insertions, 61 deletions

diff --git a/crates/hir-ty/src/builder.rs b/crates/hir-ty/src/builder.rs
index 3ae7fb2a617..dd4f1f25a69 100644
--- a/crates/hir-ty/src/builder.rs
+++ b/crates/hir-ty/src/builder.rs
@@ -6,7 +6,7 @@ use chalk_ir::{
     cast::{Cast, CastTo, Caster},
     fold::TypeFoldable,
     interner::HasInterner,
-    AdtId, BoundVar, DebruijnIndex, Scalar,
+    AdtId, DebruijnIndex, Scalar,
 };
 use hir_def::{
     builtin_type::BuiltinType, generics::TypeOrConstParamData, ConstParamId, DefWithBodyId,
@@ -16,9 +16,9 @@ use smallvec::SmallVec;
 
 use crate::{
     consteval::unknown_const_as_generic, db::HirDatabase, infer::unify::InferenceTable, primitive,
-    to_assoc_type_id, to_chalk_trait_id, utils::generics, Binders, CallableSig, ConstData,
-    ConstValue, GenericArg, GenericArgData, Interner, ProjectionTy, Substitution, TraitRef, Ty,
-    TyDefId, TyExt, TyKind, ValueTyDefId,
+    to_assoc_type_id, to_chalk_trait_id, utils::generics, Binders, BoundVar, CallableSig,
+    GenericArg, Interner, ProjectionTy, Substitution, TraitRef, Ty, TyDefId, TyExt, TyKind,
+    ValueTyDefId,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -79,20 +79,12 @@ impl<D> TyBuilder<D> {
     pub fn fill_with_bound_vars(self, debruijn: DebruijnIndex, starting_from: usize) -> Self {
         // self.fill is inlined to make borrow checker happy
         let mut this = self;
-        let other = this.param_kinds.iter().skip(this.vec.len());
+        let other = &this.param_kinds[this.vec.len()..];
         let filler = (starting_from..).zip(other).map(|(idx, kind)| match kind {
-            ParamKind::Type => {
-                GenericArgData::Ty(TyKind::BoundVar(BoundVar::new(debruijn, idx)).intern(Interner))
-                    .intern(Interner)
+            ParamKind::Type => BoundVar::new(debruijn, idx).to_ty(Interner).cast(Interner),
+            ParamKind::Const(ty) => {
+                BoundVar::new(debruijn, idx).to_const(Interner, ty.clone()).cast(Interner)
             }
-            ParamKind::Const(ty) => GenericArgData::Const(
-                ConstData {
-                    value: ConstValue::BoundVar(BoundVar::new(debruijn, idx)),
-                    ty: ty.clone(),
-                }
-                .intern(Interner),
-            )
-            .intern(Interner),
         });
         this.vec.extend(filler.take(this.remaining()).casted(Interner));
         assert_eq!(this.remaining(), 0);
@@ -102,8 +94,8 @@ impl<D> TyBuilder<D> {
     pub fn fill_with_unknown(self) -> Self {
         // self.fill is inlined to make borrow checker happy
         let mut this = self;
-        let filler = this.param_kinds.iter().skip(this.vec.len()).map(|x| match x {
-            ParamKind::Type => GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner),
+        let filler = this.param_kinds[this.vec.len()..].iter().map(|x| match x {
+            ParamKind::Type => TyKind::Error.intern(Interner).cast(Interner),
             ParamKind::Const(ty) => unknown_const_as_generic(ty.clone()),
         });
         this.vec.extend(filler.casted(Interner));
@@ -113,15 +105,13 @@ impl<D> TyBuilder<D> {
 
     pub(crate) fn fill_with_inference_vars(self, table: &mut InferenceTable<'_>) -> Self {
         self.fill(|x| match x {
-            ParamKind::Type => GenericArgData::Ty(table.new_type_var()).intern(Interner),
-            ParamKind::Const(ty) => {
-                GenericArgData::Const(table.new_const_var(ty.clone())).intern(Interner)
-            }
+            ParamKind::Type => table.new_type_var().cast(Interner),
+            ParamKind::Const(ty) => table.new_const_var(ty.clone()).cast(Interner),
         })
     }
 
     pub fn fill(mut self, filler: impl FnMut(&ParamKind) -> GenericArg) -> Self {
-        self.vec.extend(self.param_kinds.iter().skip(self.vec.len()).map(filler));
+        self.vec.extend(self.param_kinds[self.vec.len()..].iter().map(filler));
         assert_eq!(self.remaining(), 0);
         self
     }
@@ -255,7 +245,8 @@ impl TyBuilder<hir_def::AdtId> {
     ) -> Self {
         let defaults = db.generic_defaults(self.data.into());
         for default_ty in defaults.iter().skip(self.vec.len()) {
-            if let GenericArgData::Ty(x) = default_ty.skip_binders().data(Interner) {
+            // NOTE(skip_binders): we only check if the arg type is error type.
+            if let Some(x) = default_ty.skip_binders().ty(Interner) {
                 if x.is_unknown() {
                     self.vec.push(fallback().cast(Interner));
                     continue;
diff --git a/crates/hir-ty/src/chalk_ext.rs b/crates/hir-ty/src/chalk_ext.rs
index ed97bd2da4f..4f0e9dbf1e4 100644
--- a/crates/hir-ty/src/chalk_ext.rs
+++ b/crates/hir-ty/src/chalk_ext.rs
@@ -152,7 +152,7 @@ impl TyExt for Ty {
             TyKind::FnDef(def, parameters) => {
                 let callable_def = db.lookup_intern_callable_def((*def).into());
                 let sig = db.callable_item_signature(callable_def);
-                Some(sig.substitute(Interner, &parameters))
+                Some(sig.substitute(Interner, parameters))
             }
             TyKind::Closure(.., substs) => {
                 let sig_param = substs.at(Interner, 0).assert_ty_ref(Interner);
diff --git a/crates/hir-ty/src/infer/path.rs b/crates/hir-ty/src/infer/path.rs
index f580e09e912..7bb79b519e1 100644
--- a/crates/hir-ty/src/infer/path.rs
+++ b/crates/hir-ty/src/infer/path.rs
@@ -12,8 +12,7 @@ use crate::{
     builder::ParamKind,
     consteval,
     method_resolution::{self, VisibleFromModule},
-    GenericArgData, Interner, Substitution, TraitRefExt, Ty, TyBuilder, TyExt, TyKind,
-    ValueTyDefId,
+    Interner, Substitution, TraitRefExt, Ty, TyBuilder, TyExt, TyKind, ValueTyDefId,
 };
 
 use super::{ExprOrPatId, InferenceContext, TraitRef};
@@ -104,9 +103,7 @@ impl<'a> InferenceContext<'a> {
             .use_parent_substs(&parent_substs)
             .fill(|x| {
                 it.next().unwrap_or_else(|| match x {
-                    ParamKind::Type => {
-                        GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner)
-                    }
+                    ParamKind::Type => TyKind::Error.intern(Interner).cast(Interner),
                     ParamKind::Const(ty) => consteval::unknown_const_as_generic(ty.clone()),
                 })
             })
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs
index e28c87dfa46..da19dab9f98 100644
--- a/crates/hir-ty/src/lower.rs
+++ b/crates/hir-ty/src/lower.rs
@@ -678,7 +678,7 @@ impl<'a> TyLoweringContext<'a> {
         let total_len =
             parent_params + self_params + type_params + const_params + impl_trait_params;
 
-        let ty_error = GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner);
+        let ty_error = TyKind::Error.intern(Interner).cast(Interner);
 
         let mut def_generic_iter = def_generics.iter_id();
 
@@ -696,7 +696,7 @@ impl<'a> TyLoweringContext<'a> {
         let fill_self_params = || {
             for x in explicit_self_ty
                 .into_iter()
-                .map(|x| GenericArgData::Ty(x).intern(Interner))
+                .map(|x| x.cast(Interner))
                 .chain(iter::repeat(ty_error.clone()))
                 .take(self_params)
             {
diff --git a/crates/hir-ty/src/utils.rs b/crates/hir-ty/src/utils.rs
index d6638db0285..32ccd5fa43d 100644
--- a/crates/hir-ty/src/utils.rs
+++ b/crates/hir-ty/src/utils.rs
@@ -4,7 +4,7 @@
 use std::iter;
 
 use base_db::CrateId;
-use chalk_ir::{fold::Shift, BoundVar, DebruijnIndex};
+use chalk_ir::{cast::Cast, fold::Shift, BoundVar, DebruijnIndex};
 use hir_def::{
     db::DefDatabase,
     generics::{
@@ -24,8 +24,7 @@ use smallvec::{smallvec, SmallVec};
 use syntax::SmolStr;
 
 use crate::{
-    db::HirDatabase, ChalkTraitId, ConstData, ConstValue, GenericArgData, Interner, Substitution,
-    TraitRef, TraitRefExt, TyKind, WhereClause,
+    db::HirDatabase, ChalkTraitId, Interner, Substitution, TraitRef, TraitRefExt, WhereClause,
 };
 
 pub(crate) fn fn_traits(db: &dyn DefDatabase, krate: CrateId) -> impl Iterator<Item = TraitId> {
@@ -282,8 +281,8 @@ impl Generics {
         }
     }
 
-    fn parent_generics(&self) -> Option<&Generics> {
-        self.parent_generics.as_ref().map(|it| &**it)
+    pub(crate) fn parent_generics(&self) -> Option<&Generics> {
+        self.parent_generics.as_deref()
     }
 
     /// Returns a Substitution that replaces each parameter by a bound variable.
@@ -295,18 +294,10 @@ impl Generics {
         Substitution::from_iter(
             Interner,
             self.iter_id().enumerate().map(|(idx, id)| match id {
-                Either::Left(_) => GenericArgData::Ty(
-                    TyKind::BoundVar(BoundVar::new(debruijn, idx)).intern(Interner),
-                )
-                .intern(Interner),
-                Either::Right(id) => GenericArgData::Const(
-                    ConstData {
-                        value: ConstValue::BoundVar(BoundVar::new(debruijn, idx)),
-                        ty: db.const_param_ty(id),
-                    }
-                    .intern(Interner),
-                )
-                .intern(Interner),
+                Either::Left(_) => BoundVar::new(debruijn, idx).to_ty(Interner).cast(Interner),
+                Either::Right(id) => BoundVar::new(debruijn, idx)
+                    .to_const(Interner, db.const_param_ty(id))
+                    .cast(Interner),
             }),
         )
     }
@@ -316,18 +307,12 @@ impl Generics {
         Substitution::from_iter(
             Interner,
             self.iter_id().map(|id| match id {
-                Either::Left(id) => GenericArgData::Ty(
-                    TyKind::Placeholder(crate::to_placeholder_idx(db, id.into())).intern(Interner),
-                )
-                .intern(Interner),
-                Either::Right(id) => GenericArgData::Const(
-                    ConstData {
-                        value: ConstValue::Placeholder(crate::to_placeholder_idx(db, id.into())),
-                        ty: db.const_param_ty(id),
-                    }
-                    .intern(Interner),
-                )
-                .intern(Interner),
+                Either::Left(id) => {
+                    crate::to_placeholder_idx(db, id.into()).to_ty(Interner).cast(Interner)
+                }
+                Either::Right(id) => crate::to_placeholder_idx(db, id.into())
+                    .to_const(Interner, db.const_param_ty(id))
+                    .cast(Interner),
             }),
         )
     }