Merge #8348

8348: Make `Binders` more like Chalk r=flodiebold a=flodiebold

Working towards #8313.
 - hide `value`
 - use `VariableKinds`
 - adjust `subst` to be like Chalk's `substitute`
 - also clean up some other `TypeWalk` stuff to prepare for it being replaced by Chalk's `Fold`

Co-authored-by: Florian Diebold <[email protected]>

4 files changed, 12 insertions, 10 deletions

diff --git a/crates/hir/src/display.rs b/crates/hir/src/display.rs
index 993772aac..01a4d205f 100644
--- a/crates/hir/src/display.rs
+++ b/crates/hir/src/display.rs
@@ -9,6 +9,7 @@ use hir_ty::display::{
     write_bounds_like_dyn_trait_with_prefix, write_visibility, HirDisplay, HirDisplayError,
     HirFormatter,
 };
+use hir_ty::Interner;
 use syntax::ast::{self, NameOwner};
 
 use crate::{
@@ -235,7 +236,8 @@ impl HirDisplay for TypeParam {
         write!(f, "{}", self.name(f.db))?;
         let bounds = f.db.generic_predicates_for_param(self.id);
         let substs = TyBuilder::type_params_subst(f.db, self.id.parent);
-        let predicates = bounds.iter().cloned().map(|b| b.subst(&substs)).collect::<Vec<_>>();
+        let predicates =
+            bounds.iter().cloned().map(|b| b.substitute(&Interner, &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 b14c9a675..003821981 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -516,7 +516,7 @@ impl Field {
             VariantDef::Variant(it) => it.parent.id.into(),
         };
         let substs = TyBuilder::type_params_subst(db, generic_def_id);
-        let ty = db.field_types(var_id)[self.id].clone().subst(&substs);
+        let ty = db.field_types(var_id)[self.id].clone().substitute(&Interner, &substs);
         Type::new(db, self.parent.module(db).id.krate(), var_id, ty)
     }
 
@@ -702,7 +702,7 @@ impl_from!(Struct, Union, Enum for Adt);
 impl Adt {
     pub fn has_non_default_type_params(self, db: &dyn HirDatabase) -> bool {
         let subst = db.generic_defaults(self.into());
-        subst.iter().any(|ty| ty.value.is_unknown())
+        subst.iter().any(|ty| ty.skip_binders().is_unknown())
     }
 
     /// Turns this ADT into a type. Any type parameters of the ADT will be
@@ -1089,7 +1089,7 @@ pub struct TypeAlias {
 impl TypeAlias {
     pub fn has_non_default_type_params(self, db: &dyn HirDatabase) -> bool {
         let subst = db.generic_defaults(self.id.into());
-        subst.iter().any(|ty| ty.value.is_unknown())
+        subst.iter().any(|ty| ty.skip_binders().is_unknown())
     }
 
     pub fn module(self, db: &dyn HirDatabase) -> Module {
@@ -1503,7 +1503,7 @@ impl TypeParam {
         let krate = self.id.parent.module(db.upcast()).krate();
         let ty = params.get(local_idx)?.clone();
         let subst = TyBuilder::type_params_subst(db, self.id.parent);
-        let ty = ty.subst(&subst.prefix(local_idx));
+        let ty = ty.substitute(&Interner, &subst.prefix(local_idx));
         Some(Type::new_with_resolver_inner(db, krate, &resolver, ty))
     }
 }
@@ -1916,7 +1916,7 @@ impl Type {
             .iter()
             .map(|(local_id, ty)| {
                 let def = Field { parent: variant_id.into(), id: local_id };
-                let ty = ty.clone().subst(substs);
+                let ty = ty.clone().substitute(&Interner, substs);
                 (def, self.derived(ty))
             })
             .collect()
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 3bf722d2a..7955bf0b5 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -494,9 +494,9 @@ impl<'db> SemanticsImpl<'db> {
     fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
         // FIXME: this erases Substs
         let func = self.resolve_method_call(call)?;
-        let ty = self.db.value_ty(func.into());
+        let (ty, _) = self.db.value_ty(func.into()).into_value_and_skipped_binders();
         let resolver = self.analyze(call.syntax()).resolver;
-        let ty = Type::new_with_resolver(self.db, &resolver, ty.value)?;
+        let ty = Type::new_with_resolver(self.db, &resolver, ty)?;
         let mut res = ty.as_callable(self.db)?;
         res.is_bound_method = true;
         Some(res)
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index 8e9ea0a03..4ce1c2080 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -20,7 +20,7 @@ use hir_def::{
 use hir_expand::{hygiene::Hygiene, name::AsName, HirFileId, InFile};
 use hir_ty::{
     diagnostics::{record_literal_missing_fields, record_pattern_missing_fields},
-    InferenceResult, Substitution, TyLoweringContext,
+    InferenceResult, Interner, Substitution, TyLoweringContext,
 };
 use syntax::{
     ast::{self, AstNode},
@@ -339,7 +339,7 @@ impl SourceAnalyzer {
             .into_iter()
             .map(|local_id| {
                 let field = FieldId { parent: variant, local_id };
-                let ty = field_types[local_id].clone().subst(substs);
+                let ty = field_types[local_id].clone().substitute(&Interner, substs);
                 (field.into(), Type::new_with_resolver_inner(db, krate, &self.resolver, ty))
             })
             .collect()