Tests for TypeName resolution, fixes for NNBD opt-in/out mixes.

Change-Id: Ifb119a266306dbdf8a712d3110038179ee3cd7f8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/132965
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analyzer/lib/src/dart/element/type_algebra.dart

@@ -524,7 +524,7 @@ abstract class _TypeSubstitutor extends DartTypeVisitor<DartType> {
     }
 
     return NamedTypeBuilder(
-      type.isNNBD,
+      type.typeSystem,
       type.element,
       arguments,
       type.nullabilitySuffix,

pkg/analyzer/lib/src/dart/resolver/type_name_resolver.dart

@@ -325,10 +325,12 @@ class TypeNameResolver {
           node,
           element.typeParameters.length,
         );
-        return element.instantiate(
+        var type = element.instantiate(
           typeArguments: typeArguments,
           nullabilitySuffix: nullability,
         );
+        type = typeSystem.toLegacyType(type);
+        return type;
       } else if (element is NeverElementImpl) {
         _buildTypeArguments(node, 0);
         return element.instantiate(

pkg/analyzer/lib/src/generated/type_system.dart

@@ -724,17 +724,21 @@ class Dart2TypeSystem extends TypeSystem {
     if (classElement != null) {
       var typeParameters = classElement.typeParameters;
       var typeArguments = _defaultTypeArguments(typeParameters);
-      return classElement.instantiate(
+      var type = classElement.instantiate(
         typeArguments: typeArguments,
         nullabilitySuffix: nullabilitySuffix,
       );
+      type = toLegacyType(type);
+      return type;
     } else if (functionTypeAliasElement != null) {
       var typeParameters = functionTypeAliasElement.typeParameters;
       var typeArguments = _defaultTypeArguments(typeParameters);
-      return functionTypeAliasElement.instantiate(
+      var type = functionTypeAliasElement.instantiate(
         typeArguments: typeArguments,
         nullabilitySuffix: nullabilitySuffix,
       );
+      type = toLegacyType(type);
+      return type;
     } else {
       throw ArgumentError('Missing element');
     }
@@ -1744,6 +1748,11 @@ class Dart2TypeSystem extends TypeSystem {
         .refineBinaryExpressionType(leftType, operator, rightType, currentType);
   }
 
+  DartType toLegacyType(DartType type) {
+    if (isNonNullableByDefault) return type;
+    return NullabilityEliminator.perform(typeProvider, type);
+  }
+
   /**
    * Merges two types into a single type.
    * Compute the canonical representation of [T].
@@ -1791,9 +1800,7 @@ class Dart2TypeSystem extends TypeSystem {
   ) {
     return typeParameters.map((typeParameter) {
       var typeParameterImpl = typeParameter as TypeParameterElementImpl;
-      var typeArgument = typeParameterImpl.defaultType;
-      typeArgument = _toLegacyType(typeArgument);
-      return typeArgument;
+      return typeParameterImpl.defaultType;
     }).toList();
   }
 
@@ -2291,11 +2298,6 @@ class Dart2TypeSystem extends TypeSystem {
     return false;
   }
 
-  DartType _toLegacyType(DartType type) {
-    if (isNonNullableByDefault) return type;
-    return NullabilityEliminator.perform(typeProvider, type);
-  }
-
   DartType _typeParameterResolveToObjectBounds(DartType type) {
     var element = type.element;
     type = type.resolveToBound(typeProvider.objectType);

pkg/analyzer/lib/src/summary2/named_type_builder.dart

@@ -9,6 +9,7 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
+import 'package:analyzer/src/generated/type_system.dart';
 import 'package:analyzer/src/summary2/lazy_ast.dart';
 import 'package:analyzer/src/summary2/type_builder.dart';
 import 'package:meta/meta.dart';
@@ -17,8 +18,8 @@ import 'package:meta/meta.dart';
 class NamedTypeBuilder extends TypeBuilder {
   static DynamicTypeImpl get _dynamicType => DynamicTypeImpl.instance;
 
-  /// Indicates whether the library is opted into NNBD.
-  final bool isNNBD;
+  /// The type system of the library with the type name.
+  final TypeSystemImpl typeSystem;
 
   @override
   final Element element;
@@ -40,11 +41,11 @@ class NamedTypeBuilder extends TypeBuilder {
   DartType _type;
 
   NamedTypeBuilder(
-      this.isNNBD, this.element, this.arguments, this.nullabilitySuffix,
+      this.typeSystem, this.element, this.arguments, this.nullabilitySuffix,
       {this.node});
 
   factory NamedTypeBuilder.of(
-    bool isNNBD,
+    TypeSystemImpl typeSystem,
     TypeName node,
     Element element,
     NullabilitySuffix nullabilitySuffix,
@@ -57,7 +58,7 @@ class NamedTypeBuilder extends TypeBuilder {
       arguments = <DartType>[];
     }
 
-    return NamedTypeBuilder(isNNBD, element, arguments, nullabilitySuffix,
+    return NamedTypeBuilder(typeSystem, element, arguments, nullabilitySuffix,
         node: node);
   }
 
@@ -71,25 +72,29 @@ class NamedTypeBuilder extends TypeBuilder {
     if (element is ClassElement) {
       var parameters = element.typeParameters;
       var arguments = _buildArguments(parameters);
-      _type = element.instantiate(
+      var type = element.instantiate(
         typeArguments: arguments,
         nullabilitySuffix: nullabilitySuffix,
       );
+      type = typeSystem.toLegacyType(type);
+      _type = type;
     } else if (element is GenericTypeAliasElement) {
       var rawType = _getRawFunctionType(element);
       if (rawType is FunctionType) {
         var parameters = element.typeParameters;
         var arguments = _buildArguments(parameters);
         var substitution = Substitution.fromPairs(parameters, arguments);
         var instantiated = substitution.substituteType(rawType) as FunctionType;
-        _type = FunctionTypeImpl(
+        var type = FunctionTypeImpl(
           typeFormals: instantiated.typeFormals,
           parameters: instantiated.parameters,
           returnType: instantiated.returnType,
           nullabilitySuffix: nullabilitySuffix,
           element: element,
           typeArguments: arguments,
         );
+        type = typeSystem.toLegacyType(type);
+        _type = type;
       } else {
         _type = _dynamicType;
       }
@@ -126,7 +131,7 @@ class NamedTypeBuilder extends TypeBuilder {
       return this;
     }
 
-    return NamedTypeBuilder(isNNBD, element, arguments, nullabilitySuffix,
+    return NamedTypeBuilder(typeSystem, element, arguments, nullabilitySuffix,
         node: node);
   }
 
@@ -224,7 +229,7 @@ class NamedTypeBuilder extends TypeBuilder {
   NullabilitySuffix _getNullabilitySuffix(bool hasQuestion) {
     if (hasQuestion) {
       return NullabilitySuffix.question;
-    } else if (isNNBD) {
+    } else if (typeSystem.isNonNullableByDefault) {
       return NullabilitySuffix.none;
     } else {
       return NullabilitySuffix.star;

pkg/analyzer/lib/src/summary2/reference_resolver.dart

@@ -11,6 +11,7 @@ import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/resolver/scope.dart';
+import 'package:analyzer/src/generated/type_system.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary2/function_type_builder.dart';
 import 'package:analyzer/src/summary2/lazy_ast.dart';
@@ -30,6 +31,7 @@ import 'package:analyzer/src/summary2/types_builder.dart';
 /// the type is set, otherwise we keep it empty, so we will attempt to infer
 /// it later).
 class ReferenceResolver extends ThrowingAstVisitor<void> {
+  final TypeSystemImpl _typeSystem;
   final NodesToBuildType nodesToBuildType;
   final LinkedElementFactory elementFactory;
   final LibraryElement _libraryElement;
@@ -54,7 +56,8 @@ class ReferenceResolver extends ThrowingAstVisitor<void> {
     this.unitReference,
     this.isNNBD,
     this.scope,
-  ) : reference = unitReference;
+  )   : _typeSystem = _libraryElement.typeSystem,
+        reference = unitReference;
 
   @override
   void visitBlockFunctionBody(BlockFunctionBody node) {}
@@ -514,7 +517,7 @@ class ReferenceResolver extends ThrowingAstVisitor<void> {
       );
     } else {
       var builder = NamedTypeBuilder.of(
-        isNNBD,
+        _typeSystem,
         node,
         element,
         nullabilitySuffix,

pkg/analyzer/test/src/dart/resolution/test_all.dart

@@ -49,6 +49,7 @@ import 'property_access_test.dart' as property_access;
 import 'simple_identifier_test.dart' as simple_identifier;
 import 'top_type_inference_test.dart' as top_type_inference;
 import 'type_inference/test_all.dart' as type_inference;
+import 'type_name_test.dart' as type_name;
 
 main() {
   defineReflectiveSuite(() {
@@ -93,6 +94,7 @@ main() {
     property_access.main();
     simple_identifier.main();
     top_type_inference.main();
+    type_name.main();
     type_inference.main();
   }, name: 'resolution');
 }