Revision of "Adjusts dart2js backend to handle method type arguments"

pkg/compiler/lib/src/dart_types.dart

Index: pkg/compiler/lib/src/dart_types.dart
diff --git a/pkg/compiler/lib/src/dart_types.dart b/pkg/compiler/lib/src/dart_types.dart
index 685077d0b6380f328b351f118f8e5157f45b29d2..ba7fa5655d4ff5549e743182b569564b32c58c76 100644
--- a/pkg/compiler/lib/src/dart_types.dart
+++ b/pkg/compiler/lib/src/dart_types.dart
@@ -10,7 +10,7 @@ import 'common/resolution.dart' show Resolution;
 import 'common.dart';
 import 'core_types.dart';
 import 'elements/elements.dart';
-import 'elements/modelx.dart' show TypeDeclarationElementX;
+import 'elements/modelx.dart' show TypeDeclarationElementX, ErroneousElementX;
 import 'ordered_typeset.dart' show OrderedTypeSet;
 import 'util/util.dart' show equalElements;
 
@@ -124,7 +124,7 @@ abstract class DartType {
   bool get isTypeVariable => kind == TypeKind.TYPE_VARIABLE;
 
   /// Is [: true :] if this type is a malformed type.
-  bool get isMalformed => kind == TypeKind.MALFORMED_TYPE;
+  bool get isMalformed => false;
 
   /// Is `true` if this type is declared by an enum.
   bool get isEnumType => false;
@@ -164,6 +164,15 @@ abstract class DartType {
       type.accept(visitor, argument);
     }
   }
+
+  /// Returns a [DartType] which corresponds to [this] except that each
+  /// contained [MethodTypeVariableType] is replaced by a [DynamicType].
+  /// GENERIC_METHODS: Temporary, only used with '--generic-method-syntax'.
+  DartType get dynamifyMethodTypeVariableType => this;
+
+  /// Returns true iff [this] is or contains a [MethodTypeVariableType].
+  /// GENERIC_METHODS: Temporary, only used with '--generic-method-syntax'
+  bool get containsMethodTypeVariableType => false;
 }
 
 /**
@@ -234,6 +243,25 @@ class TypeVariableType extends DartType {
   String toString() => name;
 }
 
+/// Provides a thin model of method type variables: They are treated as if
+/// their value were `dynamic` when used in a type annotation, and as a
+/// malformed type when used in an `as` or `is` expression.
+class MethodTypeVariableType extends TypeVariableType {
+  MethodTypeVariableType(TypeVariableElement element) : super(element);
+
+  @override
+  bool get treatAsDynamic => true;
+
+  @override
+  bool get isMalformed => true;
+
+  @override
+  DartType get dynamifyMethodTypeVariableType => const DynamicType();
+
+  @override
+  get containsMethodTypeVariableType => true;
+}
+
 /// Internal type representing the result of analyzing a statement.
 class StatementType extends DartType {
   Element get element => null;
@@ -313,6 +341,9 @@ class MalformedType extends DartType {
   // Malformed types are treated as dynamic.
   bool get treatAsDynamic => true;
 
+  @override
+  bool get isMalformed => true;
+
   accept(DartTypeVisitor visitor, var argument) {
     return visitor.visitMalformedType(this, argument);
   }
@@ -341,9 +372,13 @@ abstract class GenericType extends DartType {
   final TypeDeclarationElement element;
   final List<DartType> typeArguments;
 
-  GenericType(TypeDeclarationElement element, this.typeArguments,
+  GenericType(TypeDeclarationElement element, List<DartType> typeArguments,
       {bool checkTypeArgumentCount: true})
-      : this.element = element {
+      : this.element = element,
+        this.typeArguments = typeArguments,
+        this.containsMethodTypeVariableType =
+            typeArguments.any(_typeContainsMethodTypeVariableType)
+  {
     assert(invariant(CURRENT_ELEMENT_SPANNABLE, element != null,
         message: "Missing element for generic type."));
     assert(invariant(element, () {
@@ -405,6 +440,17 @@ abstract class GenericType extends DartType {
     return sb.toString();
   }
 
+  @override
+  final bool containsMethodTypeVariableType;
+
+  @override
+  DartType get dynamifyMethodTypeVariableType {
+    if (!containsMethodTypeVariableType) return this;
+    List<DartType> newTypeArguments = typeArguments.map(
+        (DartType type) => type.dynamifyMethodTypeVariableType).toList();
+    return createInstantiation(newTypeArguments);
+  }
+
   int get hashCode {
     int hash = element.hashCode;
     for (DartType argument in typeArguments) {
@@ -586,11 +632,21 @@ class FunctionType extends DartType {
   }
 
   FunctionType.internal(FunctionTypedElement this.element,
-      [DartType this.returnType = const DynamicType(),
-      this.parameterTypes = const <DartType>[],
-      this.optionalParameterTypes = const <DartType>[],
-      this.namedParameters = const <String>[],
-      this.namedParameterTypes = const <DartType>[]]) {
+      [DartType returnType = const DynamicType(),
+      List<DartType> parameterTypes = const <DartType>[],
+      List<DartType> optionalParameterTypes = const <DartType>[],
+      List<String> namedParameters = const <String>[],
+      List<DartType> namedParameterTypes = const <DartType>[]])
+      : this.returnType = returnType,
+        this.parameterTypes = parameterTypes,
+        this.optionalParameterTypes = optionalParameterTypes,
+        this.namedParameters = namedParameters,
+        this.namedParameterTypes = namedParameterTypes,
+        this.containsMethodTypeVariableType =
+          returnType.containsMethodTypeVariableType ||
+          parameterTypes.any(_typeContainsMethodTypeVariableType) ||
+          optionalParameterTypes.any(_typeContainsMethodTypeVariableType) ||
+          namedParameterTypes.any(_typeContainsMethodTypeVariableType) {
     assert(invariant(
         CURRENT_ELEMENT_SPANNABLE, element == null || element.isDeclaration));
     // Assert that optional and named parameters are not used at the same time.
@@ -718,6 +774,28 @@ class FunctionType extends DartType {
 
   int computeArity() => parameterTypes.length;
 
+  @override
+  DartType get dynamifyMethodTypeVariableType {
+    if (!containsMethodTypeVariableType) return this;
+    DartType eraseIt(DartType type) => type.dynamifyMethodTypeVariableType;
+    DartType newReturnType = returnType.dynamifyMethodTypeVariableType;
+    List<DartType> newParameterTypes = parameterTypes.map(eraseIt).toList();
+    List<DartType> newOptionalParameterTypes =
+        optionalParameterTypes.map(eraseIt).toList();
+    List<DartType> newNamedParameterTypes =
+        namedParameterTypes.map(eraseIt).toList();
+    return new FunctionType.internal(
+        element,
+        newReturnType,
+        newParameterTypes,
+        newOptionalParameterTypes,
+        namedParameters,
+        newNamedParameterTypes);
+  }
+
+  @override
+  final bool containsMethodTypeVariableType;
+
   int get hashCode {
     int hash = 3 * returnType.hashCode;
     for (DartType parameter in parameterTypes) {
@@ -745,6 +823,9 @@ class FunctionType extends DartType {
   }
 }
 
+bool _typeContainsMethodTypeVariableType(DartType type) =>
+    type.containsMethodTypeVariableType;
+
 class TypedefType extends GenericType {
   DartType _unaliased;
 
@@ -1347,6 +1428,15 @@ class Types implements DartTypes {
   static ClassElement getClassContext(DartType type) {
     TypeVariableType typeVariable = type.typeVariableOccurrence;
     if (typeVariable == null) return null;
+    // GENERIC_METHODS: When generic method support is complete enough to
+    // include a runtime value for method type variables this must be updated.
+    // For full support the global assumption that all type variables are
+    // declared by the same enclosing class will not hold: Both an enclosing
+    // method and an enclosing class may define type variables, so the return
+    // type cannot be [ClassElement] and the caller must be prepared to look in
+    // two locations, not one. Currently we ignore method type variables by
+    // returning in the next statement.
+    if (typeVariable.element.typeDeclaration is! ClassElement) return null;
     return typeVariable.element.typeDeclaration;
   }