[cfe] Flatten TypeInferrer(Engine) hierarchies

Makes TypeInferrerImpl and TypeInferenceEngineImpl fully implement
the interfaces.

Change-Id: Ic058e7c3cb4d6adae98d499df74824e96a395c8c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/122780
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Dmitry Stefantsov <[email protected]>

Author: johnniwinther

pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart

@@ -9,7 +9,7 @@ class InferenceVisitor
         ExpressionVisitor1<ExpressionInferenceResult, DartType>,
         StatementVisitor<void>,
         InitializerVisitor<void> {
-  final ShadowTypeInferrer inferrer;
+  final TypeInferrerImpl inferrer;
 
   Class mapEntryClass;
 

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart

@@ -30,7 +30,6 @@ import 'package:kernel/clone.dart';
 
 import '../../base/instrumentation.dart'
     show
-        Instrumentation,
         InstrumentationValueForMember,
         InstrumentationValueForType,
         InstrumentationValueForTypeArgs;
@@ -43,7 +42,6 @@ import '../fasta_codes.dart'
         messageCantDisambiguateNotEnoughInformation,
         messageNonNullAwareSpreadIsNull,
         messageSwitchExpressionNotAssignableCause,
-        messageVoidExpression,
         noLength,
         templateCantInferTypeDueToCircularity,
         templateForInLoopElementTypeNotAssignable,
@@ -69,8 +67,6 @@ import '../source/source_class_builder.dart' show SourceClassBuilder;
 
 import '../source/source_library_builder.dart' show SourceLibraryBuilder;
 
-import '../type_inference/inference_helper.dart' show InferenceHelper;
-
 import '../type_inference/type_inference_engine.dart';
 import '../type_inference/type_inferrer.dart';
 
@@ -550,7 +546,7 @@ abstract class InitializerJudgment implements Initializer {
 }
 
 Expression checkWebIntLiteralsErrorIfUnexact(
-    ShadowTypeInferrer inferrer, int value, String literal, int charOffset) {
+    TypeInferrerImpl inferrer, int value, String literal, int charOffset) {
   if (value >= 0 && value <= (1 << 53)) return null;
   if (inferrer.isTopLevel) return null;
   if (!inferrer.library.loader.target.backendTarget
@@ -810,111 +806,6 @@ class ReturnStatementImpl extends ReturnStatement {
       : super(expression);
 }
 
-/// Concrete implementation of [TypeInferenceEngine] specialized to work with
-/// kernel objects.
-class ShadowTypeInferenceEngine extends TypeInferenceEngine {
-  ShadowTypeInferenceEngine(Instrumentation instrumentation)
-      : super(instrumentation);
-
-  @override
-  ShadowTypeInferrer createLocalTypeInferrer(Uri uri, InterfaceType thisType,
-      SourceLibraryBuilder library, InferenceDataForTesting dataForTesting) {
-    return new TypeInferrer(
-        this, uri, false, thisType, library, dataForTesting);
-  }
-
-  @override
-  ShadowTypeInferrer createTopLevelTypeInferrer(Uri uri, InterfaceType thisType,
-      SourceLibraryBuilder library, InferenceDataForTesting dataForTesting) {
-    return new TypeInferrer(this, uri, true, thisType, library, dataForTesting);
-  }
-}
-
-/// Concrete implementation of [TypeInferrer] specialized to work with kernel
-/// objects.
-class ShadowTypeInferrer extends TypeInferrerImpl {
-  @override
-  final TypePromoter typePromoter;
-
-  final InferenceDataForTesting dataForTesting;
-
-  ShadowTypeInferrer.private(
-      ShadowTypeInferenceEngine engine,
-      Uri uri,
-      bool topLevel,
-      InterfaceType thisType,
-      SourceLibraryBuilder library,
-      this.dataForTesting)
-      : typePromoter = new TypePromoter(engine.typeSchemaEnvironment),
-        super.private(engine, uri, topLevel, thisType, library);
-
-  @override
-  Expression getFieldInitializer(Field field) {
-    return field.initializer;
-  }
-
-  @override
-  ExpressionInferenceResult inferExpression(
-      Expression expression, DartType typeContext, bool typeNeeded,
-      {bool isVoidAllowed: false}) {
-    // `null` should never be used as the type context.  An instance of
-    // `UnknownType` should be used instead.
-    assert(typeContext != null);
-
-    // For full (non-top level) inference, we need access to the
-    // ExpressionGeneratorHelper so that we can perform error recovery.
-    assert(isTopLevel || helper != null);
-
-    // When doing top level inference, we skip subexpressions whose type isn't
-    // needed so that we don't induce bogus dependencies on fields mentioned in
-    // those subexpressions.
-    if (!typeNeeded) return new ExpressionInferenceResult(null, expression);
-
-    InferenceVisitor visitor = new InferenceVisitor(this);
-    ExpressionInferenceResult result;
-    if (expression is ExpressionJudgment) {
-      result = expression.acceptInference(visitor, typeContext);
-    } else {
-      result = expression.accept1(visitor, typeContext);
-    }
-    DartType inferredType = result.inferredType;
-    assert(inferredType != null, "No type inferred for $expression.");
-    if (inferredType is VoidType && !isVoidAllowed) {
-      if (expression.parent is! ArgumentsImpl) {
-        helper?.addProblem(
-            messageVoidExpression, expression.fileOffset, noLength);
-      }
-    }
-    return result;
-  }
-
-  @override
-  void inferInitializer(InferenceHelper helper, Initializer initializer) {
-    this.helper = helper;
-    // Use polymorphic dispatch on [KernelInitializer] to perform whatever
-    // kind of type inference is correct for this kind of initializer.
-    // TODO(paulberry): experiment to see if dynamic dispatch would be better,
-    // so that the type hierarchy will be simpler (which may speed up "is"
-    // checks).
-    if (initializer is InitializerJudgment) {
-      initializer.acceptInference(new InferenceVisitor(this));
-    } else {
-      initializer.accept(new InferenceVisitor(this));
-    }
-    this.helper = null;
-  }
-
-  @override
-  void inferStatement(Statement statement) {
-    // For full (non-top level) inference, we need access to the
-    // ExpressionGeneratorHelper so that we can perform error recovery.
-    if (!isTopLevel) assert(helper != null);
-    if (statement != null) {
-      statement.accept(new InferenceVisitor(this));
-    }
-  }
-}
-
 /// Concrete implementation of [TypePromoter] specialized to work with kernel
 /// objects.
 class ShadowTypePromoter extends TypePromoterImpl {

pkg/front_end/lib/src/fasta/source/source_loader.dart

@@ -80,8 +80,6 @@ import '../fasta_codes.dart'
         templateSourceOutlineSummary,
         templateUntranslatableUri;
 
-import '../kernel/kernel_shadow_ast.dart' show ShadowTypeInferenceEngine;
-
 import '../kernel/kernel_builder.dart'
     show ClassHierarchyBuilder, DelayedMember, DelayedOverrideCheck;
 
@@ -112,6 +110,8 @@ import '../scanner.dart'
         Token,
         scan;
 
+import '../type_inference/type_inference_engine.dart';
+
 import '../type_inference/type_inferrer.dart';
 
 import 'diet_listener.dart' show DietListener;
@@ -143,7 +143,7 @@ class SourceLoader extends Loader {
   DartType iterableOfBottom;
   DartType streamOfBottom;
 
-  ShadowTypeInferenceEngine typeInferenceEngine;
+  TypeInferenceEngineImpl typeInferenceEngine;
 
   Instrumentation instrumentation;
 
@@ -986,7 +986,7 @@ class SourceLoader extends Loader {
   }
 
   void createTypeInferenceEngine() {
-    typeInferenceEngine = new ShadowTypeInferenceEngine(instrumentation);
+    typeInferenceEngine = new TypeInferenceEngineImpl(instrumentation);
   }
 
   void performTopLevelInference(List<SourceClassBuilder> sourceClasses) {

pkg/front_end/lib/src/fasta/type_inference/type_inference_engine.dart

@@ -34,7 +34,7 @@ import '../kernel/kernel_builder.dart'
 
 import '../source/source_library_builder.dart' show SourceLibraryBuilder;
 
-import 'type_inferrer.dart' show TypeInferrer;
+import 'type_inferrer.dart';
 
 import 'type_schema_environment.dart' show TypeSchemaEnvironment;
 
@@ -217,6 +217,27 @@ abstract class TypeInferenceEngine {
   }
 }
 
+/// Concrete implementation of [TypeInferenceEngine] specialized to work with
+/// kernel objects.
+class TypeInferenceEngineImpl extends TypeInferenceEngine {
+  TypeInferenceEngineImpl(Instrumentation instrumentation)
+      : super(instrumentation);
+
+  @override
+  TypeInferrer createLocalTypeInferrer(Uri uri, InterfaceType thisType,
+      SourceLibraryBuilder library, InferenceDataForTesting dataForTesting) {
+    return new TypeInferrerImpl(
+        this, uri, false, thisType, library, dataForTesting);
+  }
+
+  @override
+  TypeInferrer createTopLevelTypeInferrer(Uri uri, InterfaceType thisType,
+      SourceLibraryBuilder library, InferenceDataForTesting dataForTesting) {
+    return new TypeInferrerImpl(
+        this, uri, true, thisType, library, dataForTesting);
+  }
+}
+
 class InferenceDataForTesting {
   final FlowAnalysisResult flowAnalysisResult = new FlowAnalysisResult();
 }

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

@@ -57,8 +57,6 @@ import '../kernel/expression_generator.dart' show buildIsNull;
 
 import '../kernel/kernel_shadow_ast.dart'
     show
-        ShadowTypeInferenceEngine,
-        ShadowTypeInferrer,
         VariableDeclarationImpl,
         getExplicitTypeArguments,
         getExtensionTypeParameterCount;
@@ -408,18 +406,6 @@ enum MethodContravarianceCheckKind {
 /// This class describes the interface for use by clients of type inference
 /// (e.g. BodyBuilder).  Derived classes should derive from [TypeInferrerImpl].
 abstract class TypeInferrer {
-  final CoreTypes coreTypes;
-
-  TypeInferrer.private(this.coreTypes);
-
-  factory TypeInferrer(
-      ShadowTypeInferenceEngine engine,
-      Uri uri,
-      bool topLevel,
-      InterfaceType thisType,
-      SourceLibraryBuilder library,
-      InferenceDataForTesting dataForTesting) = ShadowTypeInferrer.private;
-
   SourceLibraryBuilder get library;
 
   /// Gets the [TypePromoter] that can be used to perform type promotion within
@@ -459,19 +445,21 @@ abstract class TypeInferrer {
       InferenceHelper helper, Expression initializer, DartType declaredType);
 }
 
-/// Derived class containing generic implementations of [TypeInferrer].
-///
-/// This class contains as much of the implementation of type inference as
-/// possible without knowing the identity of the type parameters.  It defers to
-/// abstract methods for everything else.
-abstract class TypeInferrerImpl extends TypeInferrer {
+/// Concrete implementation of [TypeInferrer] specialized to work with kernel
+/// objects.
+class TypeInferrerImpl implements TypeInferrer {
   /// Marker object to indicate that a function takes an unknown number
   /// of arguments.
   static final FunctionType unknownFunction =
       new FunctionType(const [], const DynamicType());
 
   final TypeInferenceEngine engine;
 
+  @override
+  final TypePromoter typePromoter;
+
+  final InferenceDataForTesting dataForTesting;
+
   @override
   final Uri uriForInstrumentation;
 
@@ -505,20 +493,34 @@ abstract class TypeInferrerImpl extends TypeInferrer {
   /// if the last invocation didn't require any inference.
   FunctionType lastCalleeType;
 
-  TypeInferrerImpl.private(this.engine, this.uriForInstrumentation,
-      bool topLevel, this.thisType, this.library)
+  TypeInferrerImpl(this.engine, this.uriForInstrumentation, bool topLevel,
+      this.thisType, this.library, this.dataForTesting)
       : assert(library != null),
         classHierarchy = engine.classHierarchy,
         instrumentation = topLevel ? null : engine.instrumentation,
         typeSchemaEnvironment = engine.typeSchemaEnvironment,
         isTopLevel = topLevel,
-        super.private(engine.coreTypes);
+        typePromoter = new TypePromoter(engine.typeSchemaEnvironment);
+
+  CoreTypes get coreTypes => engine.coreTypes;
 
   bool get isNonNullableByDefault => library.isNonNullableByDefault;
 
-  /// Gets the type promoter that should be used to promote types during
-  /// inference.
-  TypePromoter get typePromoter;
+  @override
+  void inferInitializer(InferenceHelper helper, Initializer initializer) {
+    this.helper = helper;
+    // Use polymorphic dispatch on [KernelInitializer] to perform whatever
+    // kind of type inference is correct for this kind of initializer.
+    // TODO(paulberry): experiment to see if dynamic dispatch would be better,
+    // so that the type hierarchy will be simpler (which may speed up "is"
+    // checks).
+    if (initializer is InitializerJudgment) {
+      initializer.acceptInference(new InferenceVisitor(this));
+    } else {
+      initializer.accept(new InferenceVisitor(this));
+    }
+    this.helper = null;
+  }
 
   bool isDoubleContext(DartType typeContext) {
     // A context is a double context if double is assignable to it but int is
@@ -1266,10 +1268,6 @@ abstract class TypeInferrerImpl extends TypeInferrer {
     return null;
   }
 
-  /// Gets the initializer for the given [field], or `null` if there is no
-  /// initializer.
-  Expression getFieldInitializer(Field field);
-
   /// If the [member] is a forwarding stub, return the target it forwards to.
   /// Otherwise return the given [member].
   Member getRealTarget(Member member) {
@@ -1424,7 +1422,37 @@ abstract class TypeInferrerImpl extends TypeInferrer {
   /// the expression type and calls the appropriate specialized "infer" method.
   ExpressionInferenceResult inferExpression(
       Expression expression, DartType typeContext, bool typeNeeded,
-      {bool isVoidAllowed});
+      {bool isVoidAllowed: false}) {
+    // `null` should never be used as the type context.  An instance of
+    // `UnknownType` should be used instead.
+    assert(typeContext != null);
+
+    // For full (non-top level) inference, we need access to the
+    // ExpressionGeneratorHelper so that we can perform error recovery.
+    assert(isTopLevel || helper != null);
+
+    // When doing top level inference, we skip subexpressions whose type isn't
+    // needed so that we don't induce bogus dependencies on fields mentioned in
+    // those subexpressions.
+    if (!typeNeeded) return new ExpressionInferenceResult(null, expression);
+
+    InferenceVisitor visitor = new InferenceVisitor(this);
+    ExpressionInferenceResult result;
+    if (expression is ExpressionJudgment) {
+      result = expression.acceptInference(visitor, typeContext);
+    } else {
+      result = expression.accept1(visitor, typeContext);
+    }
+    DartType inferredType = result.inferredType;
+    assert(inferredType != null, "No type inferred for $expression.");
+    if (inferredType is VoidType && !isVoidAllowed) {
+      if (expression.parent is! ArgumentsImpl) {
+        helper?.addProblem(
+            messageVoidExpression, expression.fileOffset, noLength);
+      }
+    }
+    return result;
+  }
 
   @override
   Expression inferFieldInitializer(
@@ -2215,7 +2243,14 @@ abstract class TypeInferrerImpl extends TypeInferrer {
   ///
   /// Derived classes should override this method with logic that dispatches on
   /// the statement type and calls the appropriate specialized "infer" method.
-  void inferStatement(Statement statement);
+  void inferStatement(Statement statement) {
+    // For full (non-top level) inference, we need access to the
+    // ExpressionGeneratorHelper so that we can perform error recovery.
+    if (!isTopLevel) assert(helper != null);
+    if (statement != null) {
+      statement.accept(new InferenceVisitor(this));
+    }
+  }
 
   /// Performs the type inference steps necessary to instantiate a tear-off
   /// (if necessary).