fix check_field for recovered_variant

Author: chenyukang

compiler/rustc_hir_typeck/src/expr.rs

@@ -2330,6 +2330,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let base_ty = self.structurally_resolve_type(base.span, base_ty);
         let mut private_candidate = None;
         let mut autoderef = self.autoderef(expr.span, base_ty);
+        let mut recovered_variant = None;
         while let Some((deref_base_ty, _)) = autoderef.next() {
             debug!("deref_base_ty: {:?}", deref_base_ty);
             match deref_base_ty.kind() {
@@ -2342,6 +2343,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     let mut last_ty = None;
                     let mut nested_fields = Vec::new();
                     let mut index = None;
+                    if let Err(guard) = adt_def.non_enum_variant().has_errors() {
+                        recovered_variant = Some(guard);
+                        break;
+                    }
                     while let Some(idx) = self.tcx.find_field((adt_def.did(), ident)) {
                         let &mut first_idx = index.get_or_insert(idx);
                         let field = &adt_def.non_enum_variant().fields[idx];
@@ -2420,7 +2425,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ) {
             self.ban_take_value_of_method(expr, base_ty, field)
         } else if !base_ty.is_primitive_ty() {
-            self.ban_nonexisting_field(field, base, expr, base_ty)
+            recovered_variant
+                .unwrap_or_else(|| self.ban_nonexisting_field(field, base, expr, base_ty))
         } else {
             let field_name = field.to_string();
             let mut err = type_error_struct!(
@@ -2545,17 +2551,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ident, base, expr, base_ty
         );
 
-        for (ty, _) in self.autoderef(expr.span, base_ty) {
-            if let ty::Adt(def, _) = ty.kind()
-                && !def.is_enum()
-            {
-                let variant = def.non_enum_variant();
-                if let Err(taint) = variant.has_errors() {
-                    return taint;
-                }
-            }
-        }
-
         let mut err = self.no_such_field_err(ident, base_ty, base.hir_id);
 
         match *base_ty.peel_refs().kind() {