Refactor strong mode to use standard Analyzer errors

Also changes implicit casts errors to be determined by the type system isAssignableTo code, and updates our tests to show the user-facing error levels (StaticTypeWarningCode is upgraded to errors as far as users can see, but this wasn't visible in the tests, which showed these as "warnings").

found while looking at #26583

R=brianwilkerson@google.com, leafp@google.com

Review URL: https://codereview.chromium.org/2060013002 .

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

@@ -2851,6 +2851,24 @@ abstract class ErrorCode {
     StaticWarningCode.UNDEFINED_SUPER_SETTER,
     StaticWarningCode.VOID_RETURN_FOR_GETTER,
     StaticWarningCode.MISSING_ENUM_CONSTANT_IN_SWITCH,
+    StrongModeCode.ASSIGNMENT_CAST,
+    StrongModeCode.DOWN_CAST_COMPOSITE,
+    StrongModeCode.DOWN_CAST_IMPLICIT,
+    StrongModeCode.DYNAMIC_CAST,
+    StrongModeCode.DYNAMIC_INVOKE,
+    StrongModeCode.INFERRED_TYPE,
+    StrongModeCode.INFERRED_TYPE_ALLOCATION,
+    StrongModeCode.INFERRED_TYPE_CLOSURE,
+    StrongModeCode.INFERRED_TYPE_LITERAL,
+    StrongModeCode.INVALID_FIELD_OVERRIDE,
+    StrongModeCode.INVALID_METHOD_OVERRIDE,
+    StrongModeCode.INVALID_METHOD_OVERRIDE_FROM_BASE,
+    StrongModeCode.INVALID_METHOD_OVERRIDE_FROM_MIXIN,
+    StrongModeCode.INVALID_PARAMETER_DECLARATION,
+    StrongModeCode.INVALID_SUPER_INVOCATION,
+    StrongModeCode.NON_GROUND_TYPE_CHECK_INFO,
+    StrongModeCode.STATIC_TYPE_ERROR,
+
     TodoCode.TODO,
 
     //
@@ -5806,6 +5824,117 @@ class StaticWarningCode extends ErrorCode {
   ErrorType get type => ErrorType.STATIC_WARNING;
 }
 
+/**
+ * This class has Strong Mode specific error codes.
+ *
+ * These error codes tend to use the same message across different severity
+ * levels, so they are grouped for clarity.
+ *
+ * All of these error codes also use the "STRONG_MODE_" prefix in their name.
+ */
+class StrongModeCode extends ErrorCode {
+  static const String _implicitCastMessage =
+      'Unsound implicit cast from {0} to {1}';
+
+  static const String _typeCheckMessage =
+      'Type check failed: {0} is not of type {1}';
+
+  static const String _invalidOverrideMessage =
+      'The type of {0}.{1} ({2}) is not a '
+      'subtype of {3}.{1} ({4}).';
+
+  static const String _inferredTypeMessage = '{0} has inferred type {1}';
+
+  static const StrongModeCode DOWN_CAST_COMPOSITE = const StrongModeCode(
+      ErrorType.STATIC_WARNING, 'DOWN_CAST_COMPOSITE', _implicitCastMessage);
+
+  static const StrongModeCode DOWN_CAST_IMPLICIT = const StrongModeCode(
+      ErrorType.HINT, 'DOWN_CAST_IMPLICIT', _implicitCastMessage);
+
+  static const StrongModeCode DYNAMIC_CAST = const StrongModeCode(
+      ErrorType.HINT, 'DYNAMIC_CAST', _implicitCastMessage);
+
+  static const StrongModeCode ASSIGNMENT_CAST = const StrongModeCode(
+      ErrorType.HINT, 'ASSIGNMENT_CAST', _implicitCastMessage);
+
+  static const StrongModeCode INVALID_PARAMETER_DECLARATION =
+      const StrongModeCode(ErrorType.COMPILE_TIME_ERROR,
+          'INVALID_PARAMETER_DECLARATION', _typeCheckMessage);
+
+  static const StrongModeCode INFERRED_TYPE = const StrongModeCode(
+      ErrorType.HINT, 'INFERRED_TYPE', _inferredTypeMessage);
+
+  static const StrongModeCode INFERRED_TYPE_LITERAL = const StrongModeCode(
+      ErrorType.HINT, 'INFERRED_TYPE_LITERAL', _inferredTypeMessage);
+
+  static const StrongModeCode INFERRED_TYPE_ALLOCATION = const StrongModeCode(
+      ErrorType.HINT, 'INFERRED_TYPE_ALLOCATION', _inferredTypeMessage);
+
+  static const StrongModeCode INFERRED_TYPE_CLOSURE = const StrongModeCode(
+      ErrorType.HINT, 'INFERRED_TYPE_CLOSURE', _inferredTypeMessage);
+
+  static const StrongModeCode STATIC_TYPE_ERROR = const StrongModeCode(
+      ErrorType.COMPILE_TIME_ERROR,
+      'STATIC_TYPE_ERROR',
+      'Type check failed: {0} ({1}) is not of type {2}');
+
+  static const StrongModeCode INVALID_SUPER_INVOCATION = const StrongModeCode(
+      ErrorType.COMPILE_TIME_ERROR,
+      'INVALID_SUPER_INVOCATION',
+      "super call must be last in an initializer "
+      "list (see https://goo.gl/EY6hDP): {0}");
+
+  static const StrongModeCode NON_GROUND_TYPE_CHECK_INFO = const StrongModeCode(
+      ErrorType.HINT,
+      'NON_GROUND_TYPE_CHECK_INFO',
+      "Runtime check on non-ground type {0} may throw StrongModeError");
+
+  static const StrongModeCode DYNAMIC_INVOKE = const StrongModeCode(
+      ErrorType.HINT, 'DYNAMIC_INVOKE', '{0} requires a dynamic invoke');
+
+  static const StrongModeCode INVALID_METHOD_OVERRIDE = const StrongModeCode(
+      ErrorType.COMPILE_TIME_ERROR,
+      'INVALID_METHOD_OVERRIDE',
+      'Invalid override. $_invalidOverrideMessage');
+
+  static const StrongModeCode INVALID_METHOD_OVERRIDE_FROM_BASE =
+      const StrongModeCode(
+          ErrorType.COMPILE_TIME_ERROR,
+          'INVALID_METHOD_OVERRIDE_FROM_BASE',
+          'Base class introduces an invalid override. '
+          '$_invalidOverrideMessage');
+
+  static const StrongModeCode INVALID_METHOD_OVERRIDE_FROM_MIXIN =
+      const StrongModeCode(
+          ErrorType.COMPILE_TIME_ERROR,
+          'INVALID_METHOD_OVERRIDE_FROM_MIXIN',
+          'Mixin introduces an invalid override. $_invalidOverrideMessage');
+
+  static const StrongModeCode INVALID_FIELD_OVERRIDE = const StrongModeCode(
+      ErrorType.COMPILE_TIME_ERROR,
+      'INVALID_FIELD_OVERRIDE',
+      'Field declaration {3}.{1} cannot be '
+      'overridden in {0}.');
+
+  @override
+  final ErrorType type;
+
+  /**
+   * Initialize a newly created error code to have the given [type] and [name].
+   *
+   * The message associated with the error will be created from the given
+   * [message] template. The correction associated with the error will be
+   * created from the optional [correction] template.
+   */
+  const StrongModeCode(ErrorType type, String name, String message,
+      [String correction])
+      : type = type,
+        super('STRONG_MODE_$name', message, correction);
+
+  @override
+  ErrorSeverity get errorSeverity => type.severity;
+}
+
 /**
  * The error code indicating a marker in code for work that needs to be finished
  * or revisited.

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

@@ -30,7 +30,8 @@ import 'package:analyzer/src/generated/sdk.dart' show DartSdk, SdkLibrary;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:analyzer/src/task/dart.dart';
-import 'package:analyzer/src/task/strong/info.dart' show StaticInfo;
+import 'package:analyzer/src/task/strong/checker.dart' as checker
+    show isKnownFunction;
 
 /**
  * A visitor used to traverse an AST structure looking for additional errors and
@@ -5743,8 +5744,7 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
 
   bool _expressionIsAssignableAtType(Expression expression,
       DartType actualStaticType, DartType expectedStaticType) {
-    bool concrete =
-        _options.strongMode && StaticInfo.isKnownFunction(expression);
+    bool concrete = _options.strongMode && checker.isKnownFunction(expression);
     if (concrete) {
       actualStaticType =
           _typeSystem.typeToConcreteType(_typeProvider, actualStaticType);

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

@@ -30,8 +30,6 @@ import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/static_type_analyzer.dart';
 import 'package:analyzer/src/generated/type_system.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
-import 'package:analyzer/src/task/strong/info.dart'
-    show InferredType, StaticInfo;
 
 export 'package:analyzer/src/dart/resolver/inheritance_manager.dart';
 export 'package:analyzer/src/dart/resolver/scope.dart';
@@ -4646,7 +4644,7 @@ class InferenceContext {
   /**
    * The error listener on which to record inference information.
    */
-  final AnalysisErrorListener _errorListener;
+  final ErrorReporter _errorReporter;
 
   /**
    * If true, emit hints when types are inferred
@@ -4679,7 +4677,7 @@ class InferenceContext {
   // https://github.com/dart-lang/sdk/issues/25322
   final List<DartType> _returnStack = <DartType>[];
 
-  InferenceContext._(this._errorListener, TypeProvider typeProvider,
+  InferenceContext._(this._errorReporter, TypeProvider typeProvider,
       this._typeSystem, this._inferenceHints)
       : _typeProvider = typeProvider;
 
@@ -4758,12 +4756,22 @@ class InferenceContext {
    * [type] has been inferred as the type of [node].
    */
   void recordInference(Expression node, DartType type) {
-    StaticInfo info = InferredType.create(_typeSystem, node, type);
-    if (!_inferenceHints || info == null) {
+    if (!_inferenceHints) {
       return;
     }
-    AnalysisError error = info.toAnalysisError();
-    _errorListener.onError(error);
+
+    ErrorCode error;
+    if (node is Literal) {
+      error = StrongModeCode.INFERRED_TYPE_LITERAL;
+    } else if (node is InstanceCreationExpression) {
+      error = StrongModeCode.INFERRED_TYPE_ALLOCATION;
+    } else if (node is FunctionExpression) {
+      error = StrongModeCode.INFERRED_TYPE_CLOSURE;
+    } else {
+      error = StrongModeCode.INFERRED_TYPE;
+    }
+
+    _errorReporter.reportErrorForNode(error, node, [node, type]);
   }
 
   List<DartType> _matchTypes(InterfaceType t1, InterfaceType t2) {
@@ -5577,7 +5585,7 @@ class ResolverVisitor extends ScopedVisitor {
       strongModeHints = options.strongModeHints;
     }
     this.inferenceContext = new InferenceContext._(
-        errorListener, typeProvider, typeSystem, strongModeHints);
+        errorReporter, typeProvider, typeSystem, strongModeHints);
     this.typeAnalyzer = new StaticTypeAnalyzer(this);
   }
 

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

@@ -12,7 +12,8 @@ import 'package:analyzer/dart/element/element.dart';
 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/generated/engine.dart' show AnalysisContext;
+import 'package:analyzer/src/generated/engine.dart'
+    show AnalysisContext, AnalysisOptionsImpl;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/generated/utilities_dart.dart';
 
@@ -23,6 +24,15 @@ typedef bool _GuardedSubtypeChecker<T>(T t1, T t2, Set<Element> visited);
  * https://github.com/dart-lang/dev_compiler/blob/master/STRONG_MODE.md
  */
 class StrongTypeSystemImpl extends TypeSystem {
+  /**
+   * True if implicit casts should be allowed, otherwise false.
+   *
+   * This affects the behavior of [isAssignableTo].
+   */
+  final bool implicitCasts;
+
+  StrongTypeSystemImpl({this.implicitCasts: true});
+
   bool anyParameterType(FunctionType ft, bool predicate(DartType t)) {
     return ft.parameters.any((p) => predicate(p.type));
   }
@@ -290,6 +300,10 @@ class StrongTypeSystemImpl extends TypeSystem {
       return true;
     }
 
+    if (!implicitCasts) {
+      return false;
+    }
+
     // Don't allow implicit downcasts between function types
     // and call method objects, as these will almost always fail.
     if ((fromType is FunctionType && getCallMethodType(toType) != null) ||
@@ -309,16 +323,13 @@ class StrongTypeSystemImpl extends TypeSystem {
       return false;
     }
 
-    // If the subtype relation goes the other way, allow the implicit downcast.
-    // TODO(leafp): Emit warnings and hints for these in some way.
-    // TODO(leafp): Consider adding a flag to disable these?  Or just rely on
-    //   --warnings-as-errors?
+    // If the subtype relation goes the other way, allow the implicit
+    // downcast.
     if (isSubtypeOf(toType, fromType) || toType.isAssignableTo(fromType)) {
-      // TODO(leafp): error if type is known to be exact (literal,
-      //  instance creation).
-      // TODO(leafp): Warn on composite downcast.
-      // TODO(leafp): hint on object/dynamic downcast.
-      // TODO(leafp): Consider allowing assignment casts.
+      // TODO(leafp,jmesserly): we emit warnings/hints for these in
+      // src/task/strong/checker.dart, which is a bit inconsistent. That
+      // code should be handled into places that use isAssignableTo, such as
+      // ErrorVerifier.
       return true;
     }
 
@@ -1180,8 +1191,9 @@ abstract class TypeSystem {
    * Create either a strong mode or regular type system based on context.
    */
   static TypeSystem create(AnalysisContext context) {
-    return (context.analysisOptions.strongMode)
-        ? new StrongTypeSystemImpl()
+    var options = context.analysisOptions as AnalysisOptionsImpl;
+    return options.strongMode
+        ? new StrongTypeSystemImpl(implicitCasts: options.implicitCasts)
         : new TypeSystemImpl();
   }
 }

pkg/analyzer/lib/src/task/dart.dart

@@ -5682,9 +5682,12 @@ class StrongModeVerifyUnitTask extends SourceBasedAnalysisTask {
     CompilationUnit unit = getRequiredInput(UNIT_INPUT);
     AnalysisOptionsImpl options = context.analysisOptions;
     if (options.strongMode) {
-      unit.accept(new CodeChecker(
-          typeProvider, new StrongTypeSystemImpl(), errorListener,
-          options));
+      CodeChecker checker = new CodeChecker(
+          typeProvider,
+          new StrongTypeSystemImpl(implicitCasts: options.implicitCasts),
+          errorListener,
+          options);
+      checker.visitCompilationUnit(unit);
     }
     //
     // Record outputs.

pkg/analyzer/lib/src/task/options.dart

@@ -15,7 +15,6 @@ import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/task/general.dart';
-import 'package:analyzer/src/task/strong/info.dart';
 import 'package:analyzer/task/general.dart';
 import 'package:analyzer/task/model.dart';
 import 'package:source_span/source_span.dart';
@@ -161,8 +160,6 @@ class ErrorFilterOptionValidator extends OptionsValidator {
       _errorCodes = new HashSet<String>();
       // Engine codes.
       _errorCodes.addAll(ErrorCode.values.map((ErrorCode code) => code.name));
-      // Strong-mode codes.
-      _errorCodes.addAll(StaticInfo.names);
     }
     return _errorCodes;
   }

pkg/analyzer/lib/src/task/strong/ast_properties.dart

@@ -0,0 +1,49 @@
+// Copyright (c) 2016, 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.
+
+/// Properties that result from Strong Mode analysis on an AST.
+///
+/// These properties are not public, but provided by use of back-ends such as
+/// Dart Dev Compiler.
+
+import 'package:analyzer/analyzer.dart';
+import 'package:analyzer/dart/element/type.dart';
+
+const String _implicitCast = '_implicitCast';
+const String _hasImplicitCasts = '_hasImplicitCasts';
+const String _isDynamicInvoke = '_isDynamicInvoke';
+
+/// True if this compilation unit has any implicit casts, otherwise false.
+///
+/// See also [getImplicitCast].
+bool hasImplicitCasts(CompilationUnit node) {
+  return node.getProperty/*<bool>*/(_hasImplicitCasts) ?? false;
+}
+
+/// Sets [hasImplicitCasts] property for this compilation unit.
+void setHasImplicitCasts(CompilationUnit node, bool value) {
+  node.setProperty(_hasImplicitCasts, value == true ? true : null);
+}
+
+/// If this expression has an implicit cast, returns the type it is coerced to,
+/// otherwise returns null.
+DartType getImplicitCast(Expression node) {
+  return node.getProperty/*<DartType>*/(_implicitCast);
+}
+
+/// Sets the result of [getImplicitCast] for this node.
+void setImplicitCast(Expression node, DartType type) {
+  node.setProperty(_implicitCast, type);
+}
+
+/// True if this node is a dynamic operation that requires dispatch and/or
+/// checking at runtime.
+bool isDynamicInvoke(Expression node) {
+  return node.getProperty/*<bool>*/(_isDynamicInvoke) ?? false;
+}
+
+/// Sets [isDynamicInvoke] property for this expression
+void setIsDynamicInvoke(Expression node, bool value) {
+  node.setProperty(_isDynamicInvoke, value == true ? true : null);
+}