3 files changed, 67 insertions, 72 deletions

diff --git a/crates/hir/src/db.rs b/crates/hir/src/db.rs
index 1902a8d16..df5758342 100644
--- a/crates/hir/src/db.rs
+++ b/crates/hir/src/db.rs
@@ -1,14 +1,6 @@
 //! FIXME: write short doc here
 
-pub use hir_def::db::{
-    AttrsQuery, BlockDefMapQuery, BodyQuery, BodyWithSourceMapQuery, ConstDataQuery,
-    CrateDefMapQueryQuery, CrateLangItemsQuery, DefDatabase, DefDatabaseStorage, EnumDataQuery,
-    ExprScopesQuery, FileItemTreeQuery, FunctionDataQuery, GenericParamsQuery, ImplDataQuery,
-    ImportMapQuery, InternConstQuery, InternDatabase, InternDatabaseStorage, InternEnumQuery,
-    InternFunctionQuery, InternImplQuery, InternStaticQuery, InternStructQuery, InternTraitQuery,
-    InternTypeAliasQuery, InternUnionQuery, LangItemQuery, StaticDataQuery, StructDataQuery,
-    TraitDataQuery, TypeAliasDataQuery, UnionDataQuery,
-};
+pub use hir_def::db::*;
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, HygieneFrameQuery, InternEagerExpansionQuery,
     InternMacroQuery, MacroArgTextQuery, MacroDefQuery, MacroExpandQuery, ParseMacroExpansionQuery,
diff --git a/crates/hir/src/display.rs b/crates/hir/src/display.rs
index 97a78ca25..993772aac 100644
--- a/crates/hir/src/display.rs
+++ b/crates/hir/src/display.rs
@@ -13,29 +13,28 @@ use syntax::ast::{self, NameOwner};
 
 use crate::{
     Adt, Const, ConstParam, Enum, Field, Function, GenericParam, HasVisibility, LifetimeParam,
-    Module, Static, Struct, Substitution, Trait, Type, TypeAlias, TypeParam, Union, Variant,
+    Module, Static, Struct, Trait, TyBuilder, Type, TypeAlias, TypeParam, Union, Variant,
 };
 
 impl HirDisplay for Function {
     fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         let data = f.db.function_data(self.id);
         write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
-        let qual = &data.qualifier;
-        if qual.is_default {
+        if data.is_default() {
             write!(f, "default ")?;
         }
-        if qual.is_const {
+        if data.is_const() {
             write!(f, "const ")?;
         }
-        if qual.is_async {
+        if data.is_async() {
             write!(f, "async ")?;
         }
-        if qual.is_unsafe {
+        if data.is_unsafe() {
             write!(f, "unsafe ")?;
         }
-        if let Some(abi) = &qual.abi {
+        if let Some(abi) = &data.abi {
             // FIXME: String escape?
-            write!(f, "extern \"{}\" ", abi)?;
+            write!(f, "extern \"{}\" ", &**abi)?;
         }
         write!(f, "fn {}", data.name)?;
 
@@ -68,7 +67,7 @@ impl HirDisplay for Function {
                 write!(f, ", ")?;
             } else {
                 first = false;
-                if data.has_self_param {
+                if data.has_self_param() {
                     write_self_param(type_ref, f)?;
                     continue;
                 }
@@ -88,10 +87,10 @@ impl HirDisplay for Function {
         // `FunctionData::ret_type` will be `::core::future::Future<Output = ...>` for async fns.
         // Use ugly pattern match to strip the Future trait.
         // Better way?
-        let ret_type = if !qual.is_async {
+        let ret_type = if !data.is_async() {
             &data.ret_type
         } else {
-            match &data.ret_type {
+            match &*data.ret_type {
                 TypeRef::ImplTrait(bounds) => match &bounds[0] {
                     TypeBound::Path(path) => {
                         path.segments().iter().last().unwrap().args_and_bindings.unwrap().bindings
@@ -235,7 +234,7 @@ impl HirDisplay for TypeParam {
     fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         write!(f, "{}", self.name(f.db))?;
         let bounds = f.db.generic_predicates_for_param(self.id);
-        let substs = Substitution::type_params(f.db, self.id.parent);
+        let substs = TyBuilder::type_params_subst(f.db, self.id.parent);
         let predicates = bounds.iter().cloned().map(|b| b.subst(&substs)).collect::<Vec<_>>();
         if !(predicates.is_empty() || f.omit_verbose_types()) {
             write_bounds_like_dyn_trait_with_prefix(":", &predicates, f)?;
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 97f162315..19901ed33 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -55,11 +55,10 @@ use hir_ty::{
     autoderef, could_unify,
     method_resolution::{self, TyFingerprint},
     primitive::UintTy,
-    to_assoc_type_id,
     traits::{FnTrait, Solution, SolutionVariables},
     AliasEq, AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, CanonicalVarKinds, Cast,
-    DebruijnIndex, InEnvironment, Interner, ProjectionTy, QuantifiedWhereClause, Scalar,
-    Substitution, TraitEnvironment, Ty, TyDefId, TyKind, TyVariableKind, WhereClause,
+    DebruijnIndex, InEnvironment, Interner, QuantifiedWhereClause, Scalar, Substitution,
+    TraitEnvironment, Ty, TyBuilder, TyDefId, TyKind, TyVariableKind, WhereClause,
 };
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
@@ -515,7 +514,7 @@ impl Field {
             VariantDef::Union(it) => it.id.into(),
             VariantDef::Variant(it) => it.parent.id.into(),
         };
-        let substs = Substitution::type_params(db, generic_def_id);
+        let substs = TyBuilder::type_params_subst(db, generic_def_id);
         let ty = db.field_types(var_id)[self.id].clone().subst(&substs);
         Type::new(db, self.parent.module(db).id.krate(), var_id, ty)
     }
@@ -832,7 +831,7 @@ impl Function {
     }
 
     pub fn self_param(self, db: &dyn HirDatabase) -> Option<SelfParam> {
-        if !db.function_data(self.id).has_self_param {
+        if !db.function_data(self.id).has_self_param() {
             return None;
         }
         Some(SelfParam { func: self.id })
@@ -864,7 +863,7 @@ impl Function {
     }
 
     pub fn is_unsafe(self, db: &dyn HirDatabase) -> bool {
-        db.function_data(self.id).qualifier.is_unsafe
+        db.function_data(self.id).is_unsafe()
     }
 
     pub fn diagnostics(self, db: &dyn HirDatabase, sink: &mut DiagnosticSink) {
@@ -878,7 +877,7 @@ impl Function {
     ///
     /// This is false in the case of required (not provided) trait methods.
     pub fn has_body(self, db: &dyn HirDatabase) -> bool {
-        db.function_data(self.id).has_body
+        db.function_data(self.id).has_body()
     }
 
     /// A textual representation of the HIR of this function for debugging purposes.
@@ -957,7 +956,7 @@ impl SelfParam {
         func_data
             .params
             .first()
-            .map(|param| match *param {
+            .map(|param| match &**param {
                 TypeRef::Reference(.., mutability) => match mutability {
                     hir_def::type_ref::Mutability::Shared => Access::Shared,
                     hir_def::type_ref::Mutability::Mut => Access::Exclusive,
@@ -1011,7 +1010,7 @@ impl Const {
     }
 
     pub fn type_ref(self, db: &dyn HirDatabase) -> TypeRef {
-        db.const_data(self.id).type_ref.clone()
+        db.const_data(self.id).type_ref.as_ref().clone()
     }
 }
 
@@ -1101,7 +1100,7 @@ impl TypeAlias {
     }
 
     pub fn type_ref(self, db: &dyn HirDatabase) -> Option<TypeRef> {
-        db.type_alias_data(self.id).type_ref.clone()
+        db.type_alias_data(self.id).type_ref.as_deref().cloned()
     }
 
     pub fn ty(self, db: &dyn HirDatabase) -> Type {
@@ -1129,7 +1128,7 @@ pub struct BuiltinType {
 impl BuiltinType {
     pub fn ty(self, db: &dyn HirDatabase, module: Module) -> Type {
         let resolver = module.id.resolver(db.upcast());
-        Type::new_with_resolver(db, &resolver, Ty::builtin(self.inner))
+        Type::new_with_resolver(db, &resolver, TyBuilder::builtin(self.inner))
             .expect("crate not present in resolver")
     }
 
@@ -1502,7 +1501,7 @@ impl TypeParam {
         let resolver = self.id.parent.resolver(db.upcast());
         let krate = self.id.parent.module(db.upcast()).krate();
         let ty = params.get(local_idx)?.clone();
-        let subst = Substitution::type_params(db, self.id.parent);
+        let subst = TyBuilder::type_params_subst(db, self.id.parent);
         let ty = ty.subst(&subst.prefix(local_idx));
         Some(Type::new_with_resolver_inner(db, krate, &resolver, ty))
     }
@@ -1615,7 +1614,7 @@ impl Impl {
     // FIXME: the return type is wrong. This should be a hir version of
     // `TraitRef` (ie, resolved `TypeRef`).
     pub fn trait_(self, db: &dyn HirDatabase) -> Option<TraitRef> {
-        db.impl_data(self.id).target_trait.clone()
+        db.impl_data(self.id).target_trait.as_deref().cloned()
     }
 
     pub fn self_ty(self, db: &dyn HirDatabase) -> Type {
@@ -1703,30 +1702,29 @@ impl Type {
     fn from_def(
         db: &dyn HirDatabase,
         krate: CrateId,
-        def: impl HasResolver + Into<TyDefId> + Into<GenericDefId>,
+        def: impl HasResolver + Into<TyDefId>,
     ) -> Type {
-        let substs = Substitution::build_for_def(db, def).fill_with_unknown().build();
-        let ty = db.ty(def.into()).subst(&substs);
+        let ty = TyBuilder::def_ty(db, def.into()).fill_with_unknown().build();
         Type::new(db, krate, def, ty)
     }
 
     pub fn is_unit(&self) -> bool {
-        matches!(self.ty.interned(&Interner), TyKind::Tuple(0, ..))
+        matches!(self.ty.kind(&Interner), TyKind::Tuple(0, ..))
     }
     pub fn is_bool(&self) -> bool {
-        matches!(self.ty.interned(&Interner), TyKind::Scalar(Scalar::Bool))
+        matches!(self.ty.kind(&Interner), TyKind::Scalar(Scalar::Bool))
     }
 
     pub fn is_mutable_reference(&self) -> bool {
-        matches!(self.ty.interned(&Interner), TyKind::Ref(hir_ty::Mutability::Mut, ..))
+        matches!(self.ty.kind(&Interner), TyKind::Ref(hir_ty::Mutability::Mut, ..))
     }
 
     pub fn is_usize(&self) -> bool {
-        matches!(self.ty.interned(&Interner), TyKind::Scalar(Scalar::Uint(UintTy::Usize)))
+        matches!(self.ty.kind(&Interner), TyKind::Scalar(Scalar::Uint(UintTy::Usize)))
     }
 
     pub fn remove_ref(&self) -> Option<Type> {
-        match &self.ty.interned(&Interner) {
+        match &self.ty.kind(&Interner) {
             TyKind::Ref(.., ty) => Some(self.derived(ty.clone())),
             _ => None,
         }
@@ -1785,13 +1783,10 @@ impl Type {
     }
 
     pub fn impls_trait(&self, db: &dyn HirDatabase, trait_: Trait, args: &[Type]) -> bool {
-        let trait_ref = hir_ty::TraitRef {
-            trait_id: hir_ty::to_chalk_trait_id(trait_.id),
-            substitution: Substitution::build_for_def(db, trait_.id)
-                .push(self.ty.clone())
-                .fill(args.iter().map(|t| t.ty.clone()))
-                .build(),
-        };
+        let trait_ref = TyBuilder::trait_ref(db, trait_.id)
+            .push(self.ty.clone())
+            .fill(args.iter().map(|t| t.ty.clone()))
+            .build();
 
         let goal = Canonical {
             value: hir_ty::InEnvironment::new(self.env.env.clone(), trait_ref.cast(&Interner)),
@@ -1804,11 +1799,10 @@ impl Type {
     pub fn normalize_trait_assoc_type(
         &self,
         db: &dyn HirDatabase,
-        trait_: Trait,
         args: &[Type],
         alias: TypeAlias,
     ) -> Option<Type> {
-        let subst = Substitution::build_for_def(db, trait_.id)
+        let projection = TyBuilder::assoc_type_projection(db, alias.id)
             .push(self.ty.clone())
             .fill(args.iter().map(|t| t.ty.clone()))
             .build();
@@ -1816,10 +1810,7 @@ impl Type {
             InEnvironment::new(
                 self.env.env.clone(),
                 AliasEq {
-                    alias: AliasTy::Projection(ProjectionTy {
-                        associated_ty_id: to_assoc_type_id(alias.id),
-                        substitution: subst,
-                    }),
+                    alias: AliasTy::Projection(projection),
                     ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
                         .intern(&Interner),
                 }
@@ -1829,9 +1820,11 @@ impl Type {
         );
 
         match db.trait_solve(self.krate, goal)? {
-            Solution::Unique(SolutionVariables(subst)) => {
-                subst.value.first().map(|ty| self.derived(ty.clone()))
-            }
+            Solution::Unique(SolutionVariables(subst)) => subst
+                .value
+                .interned(&Interner)
+                .first()
+                .map(|ty| self.derived(ty.assert_ty_ref(&Interner).clone())),
             Solution::Ambig(_) => None,
         }
     }
@@ -1853,15 +1846,15 @@ impl Type {
     }
 
     pub fn is_closure(&self) -> bool {
-        matches!(&self.ty.interned(&Interner), TyKind::Closure { .. })
+        matches!(&self.ty.kind(&Interner), TyKind::Closure { .. })
     }
 
     pub fn is_fn(&self) -> bool {
-        matches!(&self.ty.interned(&Interner), TyKind::FnDef(..) | TyKind::Function { .. })
+        matches!(&self.ty.kind(&Interner), TyKind::FnDef(..) | TyKind::Function { .. })
     }
 
     pub fn is_packed(&self, db: &dyn HirDatabase) -> bool {
-        let adt_id = match self.ty.interned(&Interner) {
+        let adt_id = match self.ty.kind(&Interner) {
             &TyKind::Adt(hir_ty::AdtId(adt_id), ..) => adt_id,
             _ => return false,
         };
@@ -1874,14 +1867,14 @@ impl Type {
     }
 
     pub fn is_raw_ptr(&self) -> bool {
-        matches!(&self.ty.interned(&Interner), TyKind::Raw(..))
+        matches!(&self.ty.kind(&Interner), TyKind::Raw(..))
     }
 
     pub fn contains_unknown(&self) -> bool {
         return go(&self.ty);
 
         fn go(ty: &Ty) -> bool {
-            match ty.interned(&Interner) {
+            match ty.kind(&Interner) {
                 TyKind::Unknown => true,
 
                 TyKind::Adt(_, substs)
@@ -1889,7 +1882,9 @@ impl Type {
                 | TyKind::Tuple(_, substs)
                 | TyKind::OpaqueType(_, substs)
                 | TyKind::FnDef(_, substs)
-                | TyKind::Closure(_, substs) => substs.iter().any(go),
+                | TyKind::Closure(_, substs) => {
+                    substs.iter(&Interner).filter_map(|a| a.ty(&Interner)).any(go)
+                }
 
                 TyKind::Array(ty) | TyKind::Slice(ty) | TyKind::Raw(_, ty) | TyKind::Ref(_, ty) => {
                     go(ty)
@@ -1910,7 +1905,7 @@ impl Type {
     }
 
     pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
-        let (variant_id, substs) = match self.ty.interned(&Interner) {
+        let (variant_id, substs) = match self.ty.kind(&Interner) {
             &TyKind::Adt(hir_ty::AdtId(AdtId::StructId(s)), ref substs) => (s.into(), substs),
             &TyKind::Adt(hir_ty::AdtId(AdtId::UnionId(u)), ref substs) => (u.into(), substs),
             _ => return Vec::new(),
@@ -1927,8 +1922,11 @@ impl Type {
     }
 
     pub fn tuple_fields(&self, _db: &dyn HirDatabase) -> Vec<Type> {
-        if let TyKind::Tuple(_, substs) = &self.ty.interned(&Interner) {
-            substs.iter().map(|ty| self.derived(ty.clone())).collect()
+        if let TyKind::Tuple(_, substs) = &self.ty.kind(&Interner) {
+            substs
+                .iter(&Interner)
+                .map(|ty| self.derived(ty.assert_ty_ref(&Interner).clone()))
+                .collect()
         } else {
             Vec::new()
         }
@@ -1973,8 +1971,9 @@ impl Type {
             .strip_references()
             .substs()
             .into_iter()
-            .flat_map(|substs| substs.iter())
-            .map(move |ty| self.derived(ty.clone()))
+            .flat_map(|substs| substs.iter(&Interner))
+            .filter_map(|arg| arg.ty(&Interner).cloned())
+            .map(move |ty| self.derived(ty))
     }
 
     pub fn iterate_method_candidates<T>(
@@ -2080,7 +2079,7 @@ impl Type {
             substs: &Substitution,
             cb: &mut impl FnMut(Type),
         ) {
-            for ty in substs.iter() {
+            for ty in substs.iter(&Interner).filter_map(|a| a.ty(&Interner)) {
                 walk_type(db, &type_.derived(ty.clone()), cb);
             }
         }
@@ -2096,7 +2095,12 @@ impl Type {
                     WhereClause::Implemented(trait_ref) => {
                         cb(type_.clone());
                         // skip the self type. it's likely the type we just got the bounds from
-                        for ty in trait_ref.substitution.iter().skip(1) {
+                        for ty in trait_ref
+                            .substitution
+                            .iter(&Interner)
+                            .skip(1)
+                            .filter_map(|a| a.ty(&Interner))
+                        {
                             walk_type(db, &type_.derived(ty.clone()), cb);
                         }
                     }
@@ -2107,7 +2111,7 @@ impl Type {
 
         fn walk_type(db: &dyn HirDatabase, type_: &Type, cb: &mut impl FnMut(Type)) {
             let ty = type_.ty.strip_references();
-            match ty.interned(&Interner) {
+            match ty.kind(&Interner) {
                 TyKind::Adt(..) => {
                     cb(type_.derived(ty.clone()));
                 }