Switch to variant-granularity field type inference

3 files changed, 22 insertions, 11 deletions

diff --git a/crates/ra_hir/src/ty/infer/coerce.rs b/crates/ra_hir/src/ty/infer/coerce.rs
index 4ea038d99..54765da35 100644
--- a/crates/ra_hir/src/ty/infer/coerce.rs
+++ b/crates/ra_hir/src/ty/infer/coerce.rs
@@ -245,14 +245,17 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 ty_app!(TypeCtor::Adt(Adt::Struct(struct1)), st1),
                 ty_app!(TypeCtor::Adt(Adt::Struct(struct2)), st2),
             ) if struct1 == struct2 => {
-                let fields = struct1.fields(self.db);
-                let (last_field, prev_fields) = fields.split_last()?;
+                let field_tys = self.db.field_types(struct1.id.into());
+                let struct_data = self.db.struct_data(struct1.id.0);
+
+                let mut fields = struct_data.variant_data.fields().iter();
+                let (last_field_id, _data) = fields.next_back()?;
 
                 // Get the generic parameter involved in the last field.
                 let unsize_generic_index = {
                     let mut index = None;
                     let mut multiple_param = false;
-                    last_field.ty(self.db).walk(&mut |ty| match ty {
+                    field_tys[last_field_id].walk(&mut |ty| match ty {
                         &Ty::Param { idx, .. } => {
                             if index.is_none() {
                                 index = Some(idx);
@@ -271,8 +274,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 // Check other fields do not involve it.
                 let mut multiple_used = false;
-                prev_fields.iter().for_each(|field| {
-                    field.ty(self.db).walk(&mut |ty| match ty {
+                fields.for_each(|(field_id, _data)| {
+                    field_tys[field_id].walk(&mut |ty| match ty {
                         &Ty::Param { idx, .. } if idx == unsize_generic_index => {
                             multiple_used = true
                         }
diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
index 2996920c6..663ff9435 100644
--- a/crates/ra_hir/src/ty/infer/expr.rs
+++ b/crates/ra_hir/src/ty/infer/expr.rs
@@ -214,6 +214,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 self.unify(&ty, &expected.ty);
 
                 let substs = ty.substs().unwrap_or_else(Substs::empty);
+                let field_types =
+                    def_id.map(|it| self.db.field_types(it.into())).unwrap_or_default();
                 for (field_idx, field) in fields.iter().enumerate() {
                     let field_def = def_id.and_then(|it| match it.field(self.db, &field.name) {
                         Some(field) => Some(field),
@@ -228,8 +230,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     if let Some(field_def) = field_def {
                         self.result.record_field_resolutions.insert(field.expr, field_def);
                     }
-                    let field_ty =
-                        field_def.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs);
+                    let field_ty = field_def
+                        .map_or(Ty::Unknown, |it| field_types[it.id].clone())
+                        .subst(&substs);
                     self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
                 }
                 if let Some(expr) = spread {
@@ -252,7 +255,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
                         TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| {
                             self.write_field_resolution(tgt_expr, field);
-                            field.ty(self.db).subst(&a_ty.parameters)
+                            self.db.field_types(s.id.into())[field.id]
+                                .clone()
+                                .subst(&a_ty.parameters)
                         }),
                         _ => None,
                     },
diff --git a/crates/ra_hir/src/ty/infer/pat.rs b/crates/ra_hir/src/ty/infer/pat.rs
index c125ddfbc..641d61e87 100644
--- a/crates/ra_hir/src/ty/infer/pat.rs
+++ b/crates/ra_hir/src/ty/infer/pat.rs
@@ -27,10 +27,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let substs = ty.substs().unwrap_or_else(Substs::empty);
 
+        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
         for (i, &subpat) in subpats.iter().enumerate() {
             let expected_ty = def
                 .and_then(|d| d.field(self.db, &Name::new_tuple_field(i)))
-                .map_or(Ty::Unknown, |field| field.ty(self.db))
+                .map_or(Ty::Unknown, |field| field_tys[field.id].clone())
                 .subst(&substs);
             let expected_ty = self.normalize_associated_types_in(expected_ty);
             self.infer_pat(subpat, &expected_ty, default_bm);
@@ -56,10 +57,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let substs = ty.substs().unwrap_or_else(Substs::empty);
 
+        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
         for subpat in subpats {
             let matching_field = def.and_then(|it| it.field(self.db, &subpat.name));
-            let expected_ty =
-                matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs);
+            let expected_ty = matching_field
+                .map_or(Ty::Unknown, |field| field_tys[field.id].clone())
+                .subst(&substs);
             let expected_ty = self.normalize_associated_types_in(expected_ty);
             self.infer_pat(subpat.pat, &expected_ty, default_bm);
         }