Move DDC to analyzer-based checker

lib/src/checker/checker.dart

Index: lib/src/checker/checker.dart
diff --git a/lib/src/checker/checker.dart b/lib/src/checker/checker.dart
index 0af56752d35aae34a1044eef91a1cd44cd266f84..10bae9cfb392146a39bd8c2199f9278a4000636c 100644
--- a/lib/src/checker/checker.dart
+++ b/lib/src/checker/checker.dart
@@ -4,945 +4,4 @@
 
 library dev_compiler.src.checker.checker;
 
-import 'package:analyzer/analyzer.dart';
-import 'package:analyzer/src/generated/ast.dart';
-import 'package:analyzer/src/generated/element.dart';
-import 'package:analyzer/src/generated/scanner.dart' show Token, TokenType;
-
-import '../info.dart';
-import '../utils.dart' show getMemberType;
-import 'rules.dart';
-
-/// Checks for overriding declarations of fields and methods. This is used to
-/// check overrides between classes and superclasses, interfaces, and mixin
-/// applications.
-class _OverrideChecker {
-  bool _failure = false;
-  final TypeRules _rules;
-  final AnalysisErrorListener _reporter;
-
-  _OverrideChecker(this._rules, this._reporter);
-
-  void check(ClassDeclaration node) {
-    if (node.element.type.isObject) return;
-    _checkSuperOverrides(node);
-    _checkMixinApplicationOverrides(node);
-    _checkAllInterfaceOverrides(node);
-  }
-
-  /// Check overrides from mixin applications themselves. For example, in:
-  ///
-  ///      A extends B with E, F
-  ///
-  ///  we check:
-  ///
-  ///      B & E against B (equivalently how E overrides B)
-  ///      B & E & F against B & E (equivalently how F overrides both B and E)
-  void _checkMixinApplicationOverrides(ClassDeclaration node) {
-    var type = node.element.type;
-    var parent = type.superclass;
-    var mixins = type.mixins;
-
-    // Check overrides from applying mixins
-    for (int i = 0; i < mixins.length; i++) {
-      var seen = new Set<String>();
-      var current = mixins[i];
-      var errorLocation = node.withClause.mixinTypes[i];
-      for (int j = i - 1; j >= 0; j--) {
-        _checkIndividualOverridesFromType(
-            current, mixins[j], errorLocation, seen);
-      }
-      _checkIndividualOverridesFromType(current, parent, errorLocation, seen);
-    }
-  }
-
-  /// Check overrides between a class and its superclasses and mixins. For
-  /// example, in:
-  ///
-  ///      A extends B with E, F
-  ///
-  /// we check A against B, B super classes, E, and F.
-  ///
-  /// Internally we avoid reporting errors twice and we visit classes bottom up
-  /// to ensure we report the most immediate invalid override first. For
-  /// example, in the following code we'll report that `Test` has an invalid
-  /// override with respect to `Parent` (as opposed to an invalid override with
-  /// respect to `Grandparent`):
-  ///
-  ///     class Grandparent {
-  ///         m(A a) {}
-  ///     }
-  ///     class Parent extends Grandparent {
-  ///         m(A a) {}
-  ///     }
-  ///     class Test extends Parent {
-  ///         m(B a) {} // invalid override
-  ///     }
-  void _checkSuperOverrides(ClassDeclaration node) {
-    var seen = new Set<String>();
-    var current = node.element.type;
-    var visited = new Set<InterfaceType>();
-    do {
-      visited.add(current);
-      current.mixins.reversed
-          .forEach((m) => _checkIndividualOverridesFromClass(node, m, seen));
-      _checkIndividualOverridesFromClass(node, current.superclass, seen);
-      current = current.superclass;
-    } while (!current.isObject && !visited.contains(current));
-  }
-
-  /// Checks that implementations correctly override all reachable interfaces.
-  /// In particular, we need to check these overrides for the definitions in
-  /// the class itself and each its superclasses. If a superclass is not
-  /// abstract, then we can skip its transitive interfaces. For example, in:
-  ///
-  ///     B extends C implements G
-  ///     A extends B with E, F implements H, I
-  ///
-  /// we check:
-  ///
-  ///     C against G, H, and I
-  ///     B against G, H, and I
-  ///     E against H and I // no check against G because B is a concrete class
-  ///     F against H and I
-  ///     A against H and I
-  void _checkAllInterfaceOverrides(ClassDeclaration node) {
-    var seen = new Set<String>();
-    // Helper function to collect all reachable interfaces.
-    find(InterfaceType interfaceType, Set result) {
-      if (interfaceType == null || interfaceType.isObject) return;
-      if (result.contains(interfaceType)) return;
-      result.add(interfaceType);
-      find(interfaceType.superclass, result);
-      interfaceType.mixins.forEach((i) => find(i, result));
-      interfaceType.interfaces.forEach((i) => find(i, result));
-    }
-
-    // Check all interfaces reachable from the `implements` clause in the
-    // current class against definitions here and in superclasses.
-    var localInterfaces = new Set<InterfaceType>();
-    var type = node.element.type;
-    type.interfaces.forEach((i) => find(i, localInterfaces));
-    _checkInterfacesOverrides(node, localInterfaces, seen,
-        includeParents: true);
-
-    // Check also how we override locally the interfaces from parent classes if
-    // the parent class is abstract. Otherwise, these will be checked as
-    // overrides on the concrete superclass.
-    var superInterfaces = new Set<InterfaceType>();
-    var parent = type.superclass;
-    // TODO(sigmund): we don't seem to be reporting the analyzer error that a
-    // non-abstract class is not implementing an interface. See
-    // https://github.com/dart-lang/dart-dev-compiler/issues/25
-    while (parent != null && parent.element.isAbstract) {
-      parent.interfaces.forEach((i) => find(i, superInterfaces));
-      parent = parent.superclass;
-    }
-    _checkInterfacesOverrides(node, superInterfaces, seen,
-        includeParents: false);
-  }
-
-  /// Checks that [cls] and its super classes (including mixins) correctly
-  /// overrides each interface in [interfaces]. If [includeParents] is false,
-  /// then mixins are still checked, but the base type and it's transitive
-  /// supertypes are not.
-  ///
-  /// [cls] can be either a [ClassDeclaration] or a [InterfaceType]. For
-  /// [ClassDeclaration]s errors are reported on the member that contains the
-  /// invalid override, for [InterfaceType]s we use [errorLocation] instead.
-  void _checkInterfacesOverrides(
-      cls, Iterable<InterfaceType> interfaces, Set<String> seen,
-      {Set<InterfaceType> visited,
-      bool includeParents: true,
-      AstNode errorLocation}) {
-    var node = cls is ClassDeclaration ? cls : null;
-    var type = cls is InterfaceType ? cls : node.element.type;
-
-    if (visited == null) {
-      visited = new Set<InterfaceType>();
-    } else if (visited.contains(type)) {
-      // Malformed type.
-      return;
-    } else {
-      visited.add(type);
-    }
-
-    // Check direct overrides on [type]
-    for (var interfaceType in interfaces) {
-      if (node != null) {
-        _checkIndividualOverridesFromClass(node, interfaceType, seen);
-      } else {
-        _checkIndividualOverridesFromType(
-            type, interfaceType, errorLocation, seen);
-      }
-    }
-
-    // Check overrides from its mixins
-    for (int i = 0; i < type.mixins.length; i++) {
-      var loc =
-          errorLocation != null ? errorLocation : node.withClause.mixinTypes[i];
-      for (var interfaceType in interfaces) {
-        // We copy [seen] so we can report separately if more than one mixin or
-        // the base class have an invalid override.
-        _checkIndividualOverridesFromType(
-            type.mixins[i], interfaceType, loc, new Set.from(seen));
-      }
-    }
-
-    // Check overrides from its superclasses
-    if (includeParents) {
-      var parent = type.superclass;
-      if (parent.isObject) return;
-      var loc = errorLocation != null ? errorLocation : node.extendsClause;
-      // No need to copy [seen] here because we made copies above when reporting
-      // errors on mixins.
-      _checkInterfacesOverrides(parent, interfaces, seen,
-          visited: visited, includeParents: true, errorLocation: loc);
-    }
-  }
-
-  /// Check that individual methods and fields in [subType] correctly override
-  /// the declarations in [baseType].
-  ///
-  /// The [errorLocation] node indicates where errors are reported, see
-  /// [_checkSingleOverride] for more details.
-  ///
-  /// The set [seen] is used to avoid reporting overrides more than once. It
-  /// is used when invoking this function multiple times when checking several
-  /// types in a class hierarchy. Errors are reported only the first time an
-  /// invalid override involving a specific member is encountered.
-  _checkIndividualOverridesFromType(InterfaceType subType,
-      InterfaceType baseType, AstNode errorLocation, Set<String> seen) {
-    void checkHelper(ExecutableElement e) {
-      if (e.isStatic) return;
-      if (seen.contains(e.name)) return;
-      if (_checkSingleOverride(e, baseType, null, errorLocation)) {
-        seen.add(e.name);
-      }
-    }
-    subType.methods.forEach(checkHelper);
-    subType.accessors.forEach(checkHelper);
-  }
-
-  /// Check that individual methods and fields in [subType] correctly override
-  /// the declarations in [baseType].
-  ///
-  /// The [errorLocation] node indicates where errors are reported, see
-  /// [_checkSingleOverride] for more details.
-  _checkIndividualOverridesFromClass(
-      ClassDeclaration node, InterfaceType baseType, Set<String> seen) {
-    for (var member in node.members) {
-      if (member is ConstructorDeclaration) continue;
-      if (member is FieldDeclaration) {
-        if (member.isStatic) continue;
-        for (var variable in member.fields.variables) {
-          var element = variable.element as PropertyInducingElement;
-          var name = element.name;
-          if (seen.contains(name)) continue;
-          var getter = element.getter;
-          var setter = element.setter;
-          bool found = _checkSingleOverride(getter, baseType, variable, member);
-          if (!variable.isFinal &&
-              !variable.isConst &&
-              _checkSingleOverride(setter, baseType, variable, member)) {
-            found = true;
-          }
-          if (found) seen.add(name);
-        }
-      } else {
-        if ((member as MethodDeclaration).isStatic) continue;
-        var method = (member as MethodDeclaration).element;
-        if (seen.contains(method.name)) continue;
-        if (_checkSingleOverride(method, baseType, member, member)) {
-          seen.add(method.name);
-        }
-      }
-    }
-  }
-
-  /// Checks that [element] correctly overrides its corresponding member in
-  /// [type]. Returns `true` if an override was found, that is, if [element] has
-  /// a corresponding member in [type] that it overrides.
-  ///
-  /// The [errorLocation] is a node where the error is reported. For example, a
-  /// bad override of a method in a class with respect to its superclass is
-  /// reported directly at the method declaration. However, invalid overrides
-  /// from base classes to interfaces, mixins to the base they are applied to,
-  /// or mixins to interfaces are reported at the class declaration, since the
-  /// base class or members on their own were not incorrect, only combining them
-  /// with the interface was problematic. For example, these are example error
-  /// locations in these cases:
-  ///
-  ///     error: base class introduces an invalid override. The type of B.foo is
-  ///     not a subtype of E.foo:
-  ///       class A extends B implements E { ... }
-  ///               ^^^^^^^^^
-  ///
-  ///     error: mixin introduces an invalid override. The type of C.foo is not
-  ///     a subtype of E.foo:
-  ///       class A extends B with C implements E { ... }
-  ///                              ^
-  ///
-  /// When checking for overrides from a type and it's super types, [node] is
-  /// the AST node that defines [element]. This is used to determine whether the
-  /// type of the element could be inferred from the types in the super classes.
-  bool _checkSingleOverride(ExecutableElement element, InterfaceType type,
-      AstNode node, AstNode errorLocation) {
-    assert(!element.isStatic);
-
-    FunctionType subType = _rules.elementType(element);
-    // TODO(vsm): Test for generic
-    FunctionType baseType = getMemberType(type, element);
-
-    if (baseType == null) return false;
-    if (!_rules.isAssignable(subType, baseType)) {
-      // See whether non-assignable cases fit one of our common patterns:
-      //
-      // Common pattern 1: Inferable return type (on getters and methods)
-      //   class A {
-      //     int get foo => ...;
-      //     String toString() { ... }
-      //   }
-      //   class B extends A {
-      //     get foo => e; // no type specified.
-      //     toString() { ... } // no return type specified.
-      //   }
-      _recordMessage(new InvalidMethodOverride(
-          errorLocation, element, type, subType, baseType));
-    }
-    return true;
-  }
-
-  void _recordMessage(StaticInfo info) {
-    if (info == null) return;
-    var error = info.toAnalysisError();
-    if (error.errorCode.errorSeverity == ErrorSeverity.ERROR) _failure = true;
-    _reporter.onError(error);
-  }
-}
-
-/// Checks the body of functions and properties.
-class CodeChecker extends RecursiveAstVisitor {
-  final TypeRules rules;
-  final AnalysisErrorListener reporter;
-  final _OverrideChecker _overrideChecker;
-  bool _failure = false;
-  bool get failure => _failure || _overrideChecker._failure;
-
-  void reset() {
-    _failure = false;
-    _overrideChecker._failure = false;
-  }
-
-  CodeChecker(TypeRules rules, AnalysisErrorListener reporter)
-      : rules = rules,
-        reporter = reporter,
-        _overrideChecker = new _OverrideChecker(rules, reporter);
-
-  @override
-  void visitComment(Comment node) {
-    // skip, no need to do typechecking inside comments (they may contain
-    // comment references which would require resolution).
-  }
-
-  @override
-  void visitClassDeclaration(ClassDeclaration node) {
-    _overrideChecker.check(node);
-    super.visitClassDeclaration(node);
-  }
-
-  @override
-  void visitAssignmentExpression(AssignmentExpression node) {
-    var token = node.operator;
-    if (token.type != TokenType.EQ) {
-      _checkCompoundAssignment(node);
-    } else {
-      DartType staticType = _getStaticType(node.leftHandSide);
-      checkAssignment(node.rightHandSide, staticType);
-    }
-    node.visitChildren(this);
-  }
-
-  /// Check constructor declaration to ensure correct super call placement.
-  @override
-  void visitConstructorDeclaration(ConstructorDeclaration node) {
-    node.visitChildren(this);
-
-    final init = node.initializers;
-    for (int i = 0, last = init.length - 1; i < last; i++) {
-      final node = init[i];
-      if (node is SuperConstructorInvocation) {
-        _recordMessage(new InvalidSuperInvocation(node));
-      }
-    }
-  }
-
-  @override
-  void visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
-    var field = node.fieldName;
-    var element = field.staticElement;
-    DartType staticType = rules.elementType(element);
-    checkAssignment(node.expression, staticType);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitForEachStatement(ForEachStatement node) {
-    // Check that the expression is an Iterable.
-    var expr = node.iterable;
-    var iterableType = node.awaitKeyword != null
-        ? rules.provider.streamType
-        : rules.provider.iterableType;
-    var loopVariable = node.identifier != null
-        ? node.identifier
-        : node.loopVariable?.identifier;
-    if (loopVariable != null) {
-      var iteratorType = loopVariable.staticType;
-      var checkedType = iterableType.substitute4([iteratorType]);
-      checkAssignment(expr, checkedType);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitForStatement(ForStatement node) {
-    if (node.condition != null) {
-      checkBoolean(node.condition);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitIfStatement(IfStatement node) {
-    checkBoolean(node.condition);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitDoStatement(DoStatement node) {
-    checkBoolean(node.condition);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitWhileStatement(WhileStatement node) {
-    checkBoolean(node.condition);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitSwitchStatement(SwitchStatement node) {
-    // SwitchStatement defines a boolean conversion to check the result of the
-    // case value == the switch value, but in dev_compiler we require a boolean
-    // return type from an overridden == operator (because Object.==), so
-    // checking in SwitchStatement shouldn't be necessary.
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitListLiteral(ListLiteral node) {
-    var type = rules.provider.dynamicType;
-    if (node.typeArguments != null) {
-      var targs = node.typeArguments.arguments;
-      if (targs.length > 0) type = targs[0].type;
-    }
-    var elements = node.elements;
-    for (int i = 0; i < elements.length; i++) {
-      checkArgument(elements[i], type);
-    }
-    super.visitListLiteral(node);
-  }
-
-  @override
-  void visitMapLiteral(MapLiteral node) {
-    var ktype = rules.provider.dynamicType;
-    var vtype = rules.provider.dynamicType;
-    if (node.typeArguments != null) {
-      var targs = node.typeArguments.arguments;
-      if (targs.length > 0) ktype = targs[0].type;
-      if (targs.length > 1) vtype = targs[1].type;
-    }
-    var entries = node.entries;
-    for (int i = 0; i < entries.length; i++) {
-      var entry = entries[i];
-      checkArgument(entry.key, ktype);
-      checkArgument(entry.value, vtype);
-    }
-    super.visitMapLiteral(node);
-  }
-
-  // Check invocations
-  void checkArgumentList(ArgumentList node, FunctionType type) {
-    NodeList<Expression> list = node.arguments;
-    int len = list.length;
-    for (int i = 0; i < len; ++i) {
-      Expression arg = list[i];
-      ParameterElement element = arg.staticParameterElement;
-      if (element == null) {
-        if (type.parameters.length < len) {
-          // We found an argument mismatch, the analyzer will report this too,
-          // so no need to insert an error for this here.
-          continue;
-        }
-        element = type.parameters[i];
-        // TODO(vsm): When can this happen?
-        assert(element != null);
-      }
-      DartType expectedType = rules.elementType(element);
-      if (expectedType == null) expectedType = rules.provider.dynamicType;
-      checkArgument(arg, expectedType);
-    }
-  }
-
-  void checkArgument(Expression arg, DartType expectedType) {
-    // Preserve named argument structure, so their immediate parent is the
-    // method invocation.
-    if (arg is NamedExpression) {
-      arg = (arg as NamedExpression).expression;
-    }
-    checkAssignment(arg, expectedType);
-  }
-
-  void checkFunctionApplication(
-      Expression node, Expression f, ArgumentList list) {
-    if (rules.isDynamicCall(f)) {
-      // If f is Function and this is a method invocation, we should have
-      // gotten an analyzer error, so no need to issue another error.
-      _recordDynamicInvoke(node, f);
-    } else {
-      checkArgumentList(list, rules.getTypeAsCaller(f));
-    }
-  }
-
-  @override
-  visitMethodInvocation(MethodInvocation node) {
-    var target = node.realTarget;
-    if (rules.isDynamicTarget(target) &&
-        !_isObjectMethod(node, node.methodName)) {
-      _recordDynamicInvoke(node, target);
-
-      // Mark the tear-off as being dynamic, too. This lets us distinguish
-      // cases like:
-      //
-      //     dynamic d;
-      //     d.someMethod(...); // the whole method call must be a dynamic send.
-      //
-      // ... from case like:
-      //
-      //     SomeType s;
-      //     s.someDynamicField(...); // static get, followed by dynamic call.
-      //
-      // The first case is handled here, the second case is handled below when
-      // we call [checkFunctionApplication].
-      DynamicInvoke.set(node.methodName, true);
-    } else {
-      checkFunctionApplication(node, node.methodName, node.argumentList);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
-    checkFunctionApplication(node, node.function, node.argumentList);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitRedirectingConstructorInvocation(
-      RedirectingConstructorInvocation node) {
-    var type = node.staticElement.type;
-    checkArgumentList(node.argumentList, type);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
-    var element = node.staticElement;
-    if (element == null) {
-      _recordMessage(new MissingTypeError(node));
-    } else {
-      var type = node.staticElement.type;
-      checkArgumentList(node.argumentList, type);
-    }
-    node.visitChildren(this);
-  }
-
-  void _checkReturnOrYield(Expression expression, AstNode node,
-      {bool yieldStar: false}) {
-    var body = node.getAncestor((n) => n is FunctionBody);
-    var type = rules.getExpectedReturnType(body, yieldStar: yieldStar);
-    if (type == null) {
-      // We have a type mismatch: the async/async*/sync* modifier does
-      // not match the return or yield type.  We should have already gotten an
-      // analyzer error in this case.
-      return;
-    }
-    // TODO(vsm): Enforce void or dynamic (to void?) when expression is null.
-    if (expression != null) checkAssignment(expression, type);
-  }
-
-  @override
-  void visitExpressionFunctionBody(ExpressionFunctionBody node) {
-    _checkReturnOrYield(node.expression, node);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitReturnStatement(ReturnStatement node) {
-    _checkReturnOrYield(node.expression, node);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitYieldStatement(YieldStatement node) {
-    _checkReturnOrYield(node.expression, node, yieldStar: node.star != null);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitPropertyAccess(PropertyAccess node) {
-    var target = node.realTarget;
-    if (rules.isDynamicTarget(target) &&
-        !_isObjectProperty(target, node.propertyName)) {
-      _recordDynamicInvoke(node, target);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitPrefixedIdentifier(PrefixedIdentifier node) {
-    final target = node.prefix;
-    if (rules.isDynamicTarget(target) &&
-        !_isObjectProperty(target, node.identifier)) {
-      _recordDynamicInvoke(node, target);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitDefaultFormalParameter(DefaultFormalParameter node) {
-    // Check that defaults have the proper subtype.
-    var parameter = node.parameter;
-    var parameterType = rules.elementType(parameter.element);
-    assert(parameterType != null);
-    var defaultValue = node.defaultValue;
-    if (defaultValue != null) {
-      checkAssignment(defaultValue, parameterType);
-    }
-
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitFieldFormalParameter(FieldFormalParameter node) {
-    var element = node.element;
-    var typeName = node.type;
-    if (typeName != null) {
-      var type = rules.elementType(element);
-      var fieldElement =
-          node.identifier.staticElement as FieldFormalParameterElement;
-      var fieldType = rules.elementType(fieldElement.field);
-      if (!rules.isSubTypeOf(type, fieldType)) {
-        var staticInfo =
-            new InvalidParameterDeclaration(rules, node, fieldType);
-        _recordMessage(staticInfo);
-      }
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitInstanceCreationExpression(InstanceCreationExpression node) {
-    var arguments = node.argumentList;
-    var element = node.staticElement;
-    if (element != null) {
-      var type = rules.elementType(node.staticElement);
-      checkArgumentList(arguments, type);
-    } else {
-      _recordMessage(new MissingTypeError(node));
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitVariableDeclarationList(VariableDeclarationList node) {
-    TypeName type = node.type;
-    if (type == null) {
-      // No checks are needed when the type is var. Although internally the
-      // typing rules may have inferred a more precise type for the variable
-      // based on the initializer.
-    } else {
-      var dartType = getType(type);
-      for (VariableDeclaration variable in node.variables) {
-        var initializer = variable.initializer;
-        if (initializer != null) {
-          checkAssignment(initializer, dartType);
-        }
-      }
-    }
-    node.visitChildren(this);
-  }
-
-  void _checkRuntimeTypeCheck(AstNode node, TypeName typeName) {
-    var type = getType(typeName);
-    if (!rules.isGroundType(type)) {
-      _recordMessage(new NonGroundTypeCheckInfo(node, type));
-    }
-  }
-
-  @override
-  void visitAsExpression(AsExpression node) {
-    // We could do the same check as the IsExpression below, but that is
-    // potentially too conservative.  Instead, at runtime, we must fail hard
-    // if the Dart as and the DDC as would return different values.
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitIsExpression(IsExpression node) {
-    _checkRuntimeTypeCheck(node, node.type);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitPrefixExpression(PrefixExpression node) {
-    if (node.operator.type == TokenType.BANG) {
-      checkBoolean(node.operand);
-    } else {
-      _checkUnary(node);
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitPostfixExpression(PostfixExpression node) {
-    _checkUnary(node);
-    node.visitChildren(this);
-  }
-
-  void _checkUnary(/*PrefixExpression|PostfixExpression*/ node) {
-    var op = node.operator;
-    if (op.isUserDefinableOperator ||
-        op.type == TokenType.PLUS_PLUS ||
-        op.type == TokenType.MINUS_MINUS) {
-      if (rules.isDynamicTarget(node.operand)) {
-        _recordDynamicInvoke(node, node.operand);
-      }
-      // For ++ and --, even if it is not dynamic, we still need to check
-      // that the user defined method accepts an `int` as the RHS.
-      // We assume Analyzer has done this already.
-    }
-  }
-
-  @override
-  void visitBinaryExpression(BinaryExpression node) {
-    var op = node.operator;
-    if (op.isUserDefinableOperator) {
-      if (rules.isDynamicTarget(node.leftOperand)) {
-        // Dynamic invocation
-        // TODO(vsm): Move this logic to the resolver?
-        if (op.type != TokenType.EQ_EQ && op.type != TokenType.BANG_EQ) {
-          _recordDynamicInvoke(node, node.leftOperand);
-        }
-      } else {
-        var element = node.staticElement;
-        // Method invocation.
-        if (element is MethodElement) {
-          var type = element.type;
-          // Analyzer should enforce number of parameter types, but check in
-          // case we have erroneous input.
-          if (type.normalParameterTypes.isNotEmpty) {
-            checkArgument(node.rightOperand, type.normalParameterTypes[0]);
-          }
-        } else {
-          // TODO(vsm): Assert that the analyzer found an error here?
-        }
-      }
-    } else {
-      // Non-method operator.
-      switch (op.type) {
-        case TokenType.AMPERSAND_AMPERSAND:
-        case TokenType.BAR_BAR:
-          checkBoolean(node.leftOperand);
-          checkBoolean(node.rightOperand);
-          break;
-        case TokenType.BANG_EQ:
-          break;
-        case TokenType.QUESTION_QUESTION:
-          break;
-        default:
-          assert(false);
-      }
-    }
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitConditionalExpression(ConditionalExpression node) {
-    checkBoolean(node.condition);
-    node.visitChildren(this);
-  }
-
-  @override
-  void visitIndexExpression(IndexExpression node) {
-    var target = node.realTarget;
-    if (rules.isDynamicTarget(target)) {
-      _recordDynamicInvoke(node, target);
-    } else {
-      var element = node.staticElement;
-      if (element is MethodElement) {
-        var type = element.type;
-        // Analyzer should enforce number of parameter types, but check in
-        // case we have erroneous input.
-        if (type.normalParameterTypes.isNotEmpty) {
-          checkArgument(node.index, type.normalParameterTypes[0]);
-        }
-      } else {
-        // TODO(vsm): Assert that the analyzer found an error here?
-      }
-    }
-    node.visitChildren(this);
-  }
-
-  DartType getType(TypeName name) {
-    return (name == null) ? rules.provider.dynamicType : name.type;
-  }
-
-  /// Analyzer checks boolean conversions, but we need to check too, because
-  /// it uses the default assignability rules that allow `dynamic` and `Object`
-  /// to be assigned to bool with no message.
-  void checkBoolean(Expression expr) =>
-      checkAssignment(expr, rules.provider.boolType);
-
-  void checkAssignment(Expression expr, DartType type) {
-    if (expr is ParenthesizedExpression) {
-      checkAssignment(expr.expression, type);
-    } else {
-      _recordMessage(rules.checkAssignment(expr, type));
-    }
-  }
-
-  DartType _specializedBinaryReturnType(
-      TokenType op, DartType t1, DartType t2, DartType normalReturnType) {
-    // This special cases binary return types as per 16.26 and 16.27 of the
-    // Dart language spec.
-    switch (op) {
-      case TokenType.PLUS:
-      case TokenType.MINUS:
-      case TokenType.STAR:
-      case TokenType.TILDE_SLASH:
-      case TokenType.PERCENT:
-      case TokenType.PLUS_EQ:
-      case TokenType.MINUS_EQ:
-      case TokenType.STAR_EQ:
-      case TokenType.TILDE_SLASH_EQ:
-      case TokenType.PERCENT_EQ:
-        if (t1 == rules.provider.intType &&
-            t2 == rules.provider.intType) return t1;
-        if (t1 == rules.provider.doubleType &&
-            t2 == rules.provider.doubleType) return t1;
-        // This particular combo is not spelled out in the spec, but all
-        // implementations and analyzer seem to follow this.
-        if (t1 == rules.provider.doubleType &&
-            t2 == rules.provider.intType) return t1;
-    }
-    return normalReturnType;
-  }
-
-  void _checkCompoundAssignment(AssignmentExpression expr) {
-    var op = expr.operator.type;
-    assert(op.isAssignmentOperator && op != TokenType.EQ);
-    var methodElement = expr.staticElement;
-    if (methodElement == null) {
-      // Dynamic invocation
-      _recordDynamicInvoke(expr, expr.leftHandSide);
-    } else {
-      // Sanity check the operator
-      assert(methodElement.isOperator);
-      var functionType = methodElement.type;
-      var paramTypes = functionType.normalParameterTypes;
-      assert(paramTypes.length == 1);
-      assert(functionType.namedParameterTypes.isEmpty);
-      assert(functionType.optionalParameterTypes.isEmpty);
-
-      // Check the lhs type
-      var staticInfo;
-      var rhsType = _getStaticType(expr.rightHandSide);
-      var lhsType = _getStaticType(expr.leftHandSide);
-      var returnType = _specializedBinaryReturnType(
-          op, lhsType, rhsType, functionType.returnType);
-
-      if (!rules.isSubTypeOf(returnType, lhsType)) {
-        final numType = rules.provider.numType;
-        // Try to fix up the numerical case if possible.
-        if (rules.isSubTypeOf(lhsType, numType) &&
-            rules.isSubTypeOf(lhsType, rhsType)) {
-          // This is also slightly different from spec, but allows us to keep
-          // compound operators in the int += num and num += dynamic cases.
-          staticInfo = DownCast.create(
-              rules, expr.rightHandSide, Coercion.cast(rhsType, lhsType));
-          rhsType = lhsType;
-        } else {
-          // Static type error
-          staticInfo = new StaticTypeError(rules, expr, lhsType);
-        }
-        _recordMessage(staticInfo);
-      }
-
-      // Check the rhs type
-      if (staticInfo is! CoercionInfo) {
-        var paramType = paramTypes.first;
-        staticInfo = rules.checkAssignment(expr.rightHandSide, paramType);
-        _recordMessage(staticInfo);
-      }
-    }
-  }
-
-  bool _isObjectGetter(Expression target, SimpleIdentifier id) {
-    PropertyAccessorElement element =
-        rules.provider.objectType.element.getGetter(id.name);
-    return (element != null && !element.isStatic);
-  }
-
-  bool _isObjectMethod(Expression target, SimpleIdentifier id) {
-    MethodElement element =
-        rules.provider.objectType.element.getMethod(id.name);
-    return (element != null && !element.isStatic);
-  }
-
-  bool _isObjectProperty(Expression target, SimpleIdentifier id) {
-    return _isObjectGetter(target, id) || _isObjectMethod(target, id);
-  }
-
-  DartType _getStaticType(Expression expr) {
-    var type = expr.staticType;
-    if (type == null) {
-      reporter.onError(new MissingTypeError(expr).toAnalysisError());
-    }
-    return type ?? rules.provider.dynamicType;
-  }
-
-  void _recordDynamicInvoke(AstNode node, AstNode target) {
-    reporter.onError(new DynamicInvoke(rules, node).toAnalysisError());
-    // TODO(jmesserly): we may eventually want to record if the whole operation
-    // (node) was dynamic, rather than the target, but this is an easier fit
-    // with what we used to do.
-    DynamicInvoke.set(target, true);
-  }
-
-  void _recordMessage(StaticInfo info) {
-    if (info == null) return;
-    var error = info.toAnalysisError();
-    if (error.errorCode.errorSeverity == ErrorSeverity.ERROR) _failure = true;
-    reporter.onError(error);
-
-    if (info is CoercionInfo) {
-      // TODO(jmesserly): if we're run again on the same AST, we'll produce the
-      // same annotations. This should be harmless. This might go away once
-      // CodeChecker is integrated better with analyzer, as it will know that
-      // checking has already been performed.
-      // assert(CoercionInfo.get(info.node) == null);
-      CoercionInfo.set(info.node, info);
-    }
-  }
-}
+export 'package:analyzer/src/task/strong/checker.dart';