Begin writing tests of the runtime checks needed for Dart 2.0 soundness.

pkg/analyzer/test/src/task/strong/front_end_runtime_check_test.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/generated/resolver.dart';
+import 'package:analyzer/src/generated/type_system.dart';
+import 'package:analyzer/src/generated/utilities_dart.dart';
+import 'package:analyzer/src/task/strong/ast_properties.dart';
+import 'package:front_end/src/base/instrumentation.dart' as fasta;
+import 'package:front_end/src/fasta/compiler_context.dart' as fasta;
+import 'package:front_end/src/fasta/testing/validating_instrumentation.dart'
+    as fasta;
+import 'package:kernel/kernel.dart' as fasta;
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'front_end_test_common.dart';
+
+main() {
+  // Use a group() wrapper to specify the timeout.
+  group('front_end_runtime_check_test', () {
+    defineReflectiveSuite(() {
+      defineReflectiveTests(RunFrontEndRuntimeCheckTest);
+    });
+  }, timeout: new Timeout(const Duration(seconds: 120)));
+}
+
+@reflectiveTest
+class RunFrontEndRuntimeCheckTest extends RunFrontEndTest {
+  @override
+  get testSubdir => 'runtime_checks';
+
+  @override
+  void visitUnit(TypeProvider typeProvider, CompilationUnit unit,
+      fasta.ValidatingInstrumentation validation, Uri uri) {
+    unit.accept(new _InstrumentationVisitor(
+        new StrongTypeSystemImpl(typeProvider), validation, uri));
+  }
+}
+
+/// Visitor for ASTs that reports instrumentation for strong mode runtime
+/// checks.
+///
+/// Note: this visitor doesn't attempt to report all runtime checks inserted by
+/// analyzer; just the ones necessary to validate the front end tests.  This
+/// visitor might need to be updated as more front end tests are added.
+class _InstrumentationVisitor extends GeneralizingAstVisitor<Null> {
+  final fasta.Instrumentation _instrumentation;
+  final Uri uri;
+  final StrongTypeSystemImpl _typeSystem;
+  final _elementNamer = new ElementNamer(null);
+
+  _InstrumentationVisitor(this._typeSystem, this._instrumentation, this.uri);
+
+  @override
+  visitAssignmentExpression(AssignmentExpression node) {
+    super.visitAssignmentExpression(node);
+    var leftHandSide = node.leftHandSide;
+    if (leftHandSide is PrefixedIdentifier) {
+      var staticElement = leftHandSide.identifier.staticElement;
+      if (staticElement is PropertyAccessorElement && staticElement.isSetter) {
+        var target = leftHandSide.prefix;
+        _annotateCheckCall(
+            staticElement,
+            target is ThisExpression,
+            isDynamicInvoke(leftHandSide.identifier),
+            target.staticType,
+            [],
+            [node.rightHandSide],
+            leftHandSide.identifier.offset);
+      }
+    }
+  }
+
+  @override
+  visitClassDeclaration(ClassDeclaration node) {
+    super.visitClassDeclaration(node);
+    _emitForwardingStubs(node, node.name.offset);
+  }
+
+  @override
+  visitClassTypeAlias(ClassTypeAlias node) {
+    super.visitClassTypeAlias(node);
+    _emitForwardingStubs(node, node.name.offset);
+  }
+
+  @override
+  visitFormalParameter(FormalParameter node) {
+    super.visitFormalParameter(node);
+    if (node is DefaultFormalParameter) {
+      // Already handled via the contained parameter ast object
+      return;
+    }
+    _annotateFormalParameter(node.element, node.identifier.offset,
+        node.getAncestor((n) => n is ClassDeclaration));
+  }
+
+  @override
+  visitMethodInvocation(MethodInvocation node) {
+    super.visitMethodInvocation(node);
+    var staticElement = node.methodName.staticElement;
+    var target = node.target;
+    var isThis = target is ThisExpression || target == null;
+    if (staticElement is PropertyAccessorElement) {
+      // Method invocation resolves to a getter; treat it as a get followed by a
+      // function invocation.
+      _annotateCheckReturn(
+          getImplicitOperationCast(node), node.methodName.offset);
+      _annotateCheckCall(
+          null,
+          isThis,
+          isDynamicInvoke(node.methodName),
+          null,
+          node.typeArguments?.arguments,
+          node.argumentList.arguments,
+          node.argumentList.offset);
+    } else {
+      _annotateCheckReturn(getImplicitCast(node), node.argumentList.offset);
+      _annotateCheckCall(
+          staticElement,
+          isThis,
+          isDynamicInvoke(node.methodName),
+          target?.staticType,
+          node.typeArguments?.arguments,
+          node.argumentList.arguments,
+          node.argumentList.offset);
+    }
+  }
+
+  @override
+  visitPrefixedIdentifier(PrefixedIdentifier node) {
+    super.visitPrefixedIdentifier(node);
+    if (node.identifier.staticElement is MethodElement) {
+      _annotateTearOff(node, node.identifier.offset);
+    }
+  }
+
+  @override
+  visitTypeParameter(TypeParameter node) {
+    super.visitTypeParameter(node);
+    if (node.parent.parent is MethodDeclaration) {
+      _annotateFormalParameter(node.element, node.name.offset,
+          node.getAncestor((n) => n is ClassDeclaration));
+    }
+  }
+
+  @override
+  visitVariableDeclaration(VariableDeclaration node) {
+    super.visitVariableDeclaration(node);
+    if (node.parent.parent is FieldDeclaration) {
+      FieldElement element = node.element;
+      if (!element.isFinal) {
+        var setter = element.setter;
+        _annotateFormalParameter(setter.parameters[0], node.name.offset,
+            node.getAncestor((n) => n is ClassDeclaration));
+      }
+    }
+  }
+
+  /// Generates the appropriate `@checkCall` annotation (if any) for a call
+  /// site.
+  ///
+  /// An annotation of `@checkCall=dynamic` indicates that the call is dynamic
+  /// (so it will have to be fully type checked).  An annotation of
+  /// "@checkCall=interface(args)" indicates that the call statically resolves
+  /// to a member of an interface, but some of the arguments are "semi-typed" so
+  /// they may have to be type checked.  `args` lists the positional indices of
+  /// the semi-typed arguments (counting from 0).  If any type parameters need
+  /// to be checked, they are also listed by index, enclosed in `<>`.  For
+  /// example, `@checkCall=interface(<0>,1)` means that type parameter 0 and
+  /// regular parameter 1 are semi-typed.
+  ///
+  /// [staticElement] is the element being invoked, or `null` if there is no
+  /// static element (either because this is a dynamic invocation or because the
+  /// thing being invoked is function-typed).
+  ///
+  /// [isThis] indicates whether the receiver of the invocation is `this`.
+  ///
+  /// [isDynamic] indicates whether analyzer has classified this invocation as a
+  /// dynamic invocation.
+  ///
+  /// [targetType] is the type of the target of the invocation, or `null` if
+  /// there is no target (e.g. because of implicit `this` or because the thing
+  /// being invoked is function-typed).
+  ///
+  /// [typeArguments] and [arguments] are the type arguments and regular
+  /// arguments of the invocation, respectively.
+  ///
+  /// [offset] is the location of the invocation in source code.
+  void _annotateCheckCall(
+      Element staticElement,
+      bool isThis,
+      bool isDynamic,
+      DartType targetType,
+      List<TypeAnnotation> typeArguments,
+      List<Expression> arguments,
+      int offset) {
+    if (staticElement is FunctionElement &&
+        staticElement.enclosingElement is CompilationUnitElement) {
+      // Invocation of a top level function; no annotation needed.
+      return;
+    }
+    if (isDynamic) {
+      if (targetType == null &&
+          staticElement != null &&
+          staticElement is! MethodElement) {
+        // Sometimes analyzer annotates invocations of function objects as
+        // dynamic (presumably due to "dynamic is bottom" behavior).  Ignore
+        // this.
+      } else {
+        _recordCheckCall(offset, 'dynamic');
+        return;
+      }
+    }
+    if (staticElement is MethodElement && isThis) {
+      // Calls through "this" are always typed because the type parameters match
+      // up perfectly; no annotation needed.
+      return;
+    }
+    var semiTypedArgs = <String>[];
+    if (typeArguments != null) {
+      for (int argPosition = 0;
+          argPosition < typeArguments.length;
+          argPosition++) {
+        DartType getArgument(FunctionType functionType) {
+          return functionType.typeFormals[argPosition].bound;
+        }
+
+        if (_isArgumentSemiTyped(targetType, staticElement, getArgument)) {
+          semiTypedArgs.add('<$argPosition>');
+        }
+      }
+    }
+    int argPosition = 0;
+    for (var argument in arguments) {
+      assert(argument is! NamedExpression); // TODO(paulberry): handle this
+      DartType getArgument(FunctionType functionType) {
+        // TODO(paulberry): handle named parameters
+        if (argPosition >= functionType.normalParameterTypes.length) {
+          return functionType.optionalParameterTypes[
+              argPosition - functionType.normalParameterTypes.length];
+        } else {
+          return functionType.normalParameterTypes[argPosition];
+        }
+      }
+
+      if (_isArgumentSemiTyped(targetType, staticElement, getArgument)) {
+        semiTypedArgs.add('$argPosition');
+      }
+      ++argPosition;
+    }
+    if (semiTypedArgs.isEmpty) {
+      // We don't annotate invocations where all arguments are typed because
+      // that's the common case.
+    } else {
+      _recordCheckCall(
+          offset, 'interface(semiTyped:${semiTypedArgs.join(',')})');
+    }
+  }
+
+  /// Generates the appropriate `@checkReturn` annotation (if any) for a call
+  /// site.
+  ///
+  /// An annotation of `@checkReturn=type` indicates that the value returned by
+  /// the call will have to be checked to make sure it is an instance of the
+  /// given type.
+  void _annotateCheckReturn(DartType castType, int offset) {
+    if (castType != null) {
+      _recordCheckReturn(offset, castType);
+    }
+  }
+
+  /// Generates the appropriate `@checkFormal` annotation (if any) for a method
+  /// formal parameter, method type parameter, or field declaration.
+  ///
+  /// When this annotation is generated for a field declaration, it implicitly
+  /// refers to the value parameter of the synthetic setter.
+  ///
+  /// An annotation of `@checkFormal=unsafe` indicates that the parameter needs
+  /// to be type checked regardless of the call site.
+  ///
+  /// An annotation of `@checkFormal=semiSafe` indicates that the parameter
+  /// needs to be type checked when corresponding argument at the call site is
+  /// considered "semi-typed".
+  ///
+  /// No annotation indicates that the parameter only needs to be type checked
+  /// if the call site is a dynamic invocation.
+  void _annotateFormalParameter(
+      Element element, int offset, ClassDeclaration cls) {
+    if (element is ParameterElement && element.isCovariant) {
+      _recordCheckFormal(offset, 'unsafe');
+    } else if (cls != null) {
+      var covariantParams = getClassCovariantParameters(cls);
+      if (covariantParams != null && covariantParams.contains(element)) {
+        _recordCheckFormal(offset, 'semiSafe');
+      }
+    }
+  }
+
+  /// Generates the appropriate `@checkTearOff` annotation (if any) for a call
+  /// site.
+  ///
+  /// An annotation of `@checkTearOff=type` indicates that the torn off function
+  /// will have to be checked to make sure it is an instance of the given type.
+  void _annotateTearOff(Expression node, int offset) {
+    // TODO(paulberry): handle dynamic tear offs
+    // Note: we don't annotate that non-dynamic tear offs use "interface"
+    // dispatch because that's the common case.
+    var castType = getImplicitCast(node);
+    if (castType != null) {
+      _recordCheckTearOff(offset, castType);
+    }
+  }
+
+  /// Generates the appropriate `@forwardingStub` annotation (if any) for a
+  /// class declaration or mixin application.
+  ///
+  /// An annotation of `@forwardingStub=rettype name(args)` indicates that a
+  /// forwarding stub must be inserted into the class having the given name and
+  /// return type.  Each argument is listed in `args` as `safety type name`,
+  /// where safety is one of `safe` or `semiSafe`.
+  void _emitForwardingStubs(Declaration node, int offset) {
+    var covariantParams = getSuperclassCovariantParameters(node);
+    if (covariantParams != null && covariantParams.isNotEmpty) {
+      for (var member
+          in covariantParams.map((p) => p.enclosingElement).toSet()) {
+        var memberName = member.name;
+        if (member is PropertyAccessorElement) {
+          throw new UnimplementedError(); // TODO(paulberry)
+        } else if (member is MethodElement) {
+          var paramDescrs = <String>[];
+          for (var param in member.parameters) {
+            // TODO(paulberry): test the safe case
+            var safetyDescr =
+                covariantParams.contains(param) ? 'semiSafe' : 'safe';
+            var typeDescr = _typeToString(param.type);
+            var paramName = param.name;
+            // TODO(paulberry): if necessary, support other parameter kinds
+            assert(param.parameterKind == ParameterKind.REQUIRED);
+            paramDescrs.add('$safetyDescr $typeDescr $paramName');
+          }
+          var returnTypeDescr = _typeToString(member.returnType);
+          var stub = '$returnTypeDescr $memberName(${paramDescrs.join(', ')})';
+          _recordForwardingStub(offset, stub);
+        } else {
+          throw new StateError('Unexpected covariant member $member');
+        }
+      }
+    }
+  }
+
+  /// Determines whether an argument at a call site should be considered
+  /// "semi-typed".
+  ///
+  /// [targetType] indicates the type of the interface being invoked.
+  ///
+  /// [invocationTarget] is the method or getter/setter being invoked.
+  ///
+  /// [getArgument] is a callback for accessing the corresponding argument type
+  /// from a [FunctionType].
+  bool _isArgumentSemiTyped(InterfaceType targetType, Element invocationTarget,
+      DartType getArgument(FunctionType functionType)) {
+    bool _checkTypes(DartType originalArgumentType,
+        DartType lookupArgumentType(InterfaceType interfaceType)) {
+      // If the target type lacks type parameters, then everything is safe.
+      if (targetType.typeParameters.isEmpty) return false;
+
+      // To see if this argument needs to be semi-typed, we try substituting
+      // bottom in for all the active type parameters.  If the resulting
+      // argument static type is a supertype of its current static type, then
+      // that means that regardless of what we pass in, it won't fail a type
+      // check.
+      var substitutedInterfaceType = targetType.element.type.instantiate(
+          new List<DartType>.filled(
+              targetType.typeParameters.length, BottomTypeImpl.instance));
+      var substitutedArgumentType =
+          lookupArgumentType(substitutedInterfaceType);
+      return !_typeSystem.isSubtypeOf(
+          originalArgumentType, substitutedArgumentType);
+    }
+
+    if (invocationTarget is LocalVariableElement || invocationTarget == null) {
+      // This is an invocation of a closure, so every argument is semi-typed.
+      return true;
+    } else if (invocationTarget is PropertyAccessorElement &&
+        invocationTarget.isSetter) {
+      return _checkTypes(
+          invocationTarget.parameters[0].type,
+          (InterfaceType type) => type
+              .lookUpSetter(invocationTarget.name, invocationTarget.library)
+              .parameters[0]
+              .type);
+    } else if (invocationTarget is MethodElement) {
+      return _checkTypes(
+          getArgument(invocationTarget.type),
+          (InterfaceType type) => getArgument(type
+              .lookUpMethod(invocationTarget.name, invocationTarget.library)
+              .type));
+    } else {
+      throw new UnimplementedError(
+          'Unexpected invocation target type: ${invocationTarget.runtimeType}');
+    }
+  }
+
+  void _recordCheckCall(int offset, String safety) {
+    _instrumentation.record(uri, offset, 'checkCall',
+        new fasta.InstrumentationValueLiteral(safety));
+  }
+
+  void _recordCheckFormal(int offset, String safety) {
+    _instrumentation.record(uri, offset, 'checkFormal',
+        new fasta.InstrumentationValueLiteral(safety));
+  }
+
+  void _recordCheckReturn(int offset, DartType castType) {
+    _instrumentation.record(uri, offset, 'checkReturn',
+        new InstrumentationValueForType(castType, _elementNamer));
+  }
+
+  void _recordCheckTearOff(int offset, DartType castType) {
+    _instrumentation.record(uri, offset, 'checkTearOff',
+        new InstrumentationValueForType(castType, _elementNamer));
+  }
+
+  void _recordForwardingStub(int offset, String descr) {
+    _instrumentation.record(uri, offset, 'forwardingStub',
+        new fasta.InstrumentationValueLiteral(descr));
+  }
+
+  String _typeToString(DartType type) {
+    return new InstrumentationValueForType(type, _elementNamer).toString();
+  }
+}