generic method type parameter inference

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

 // Copyright (c) 2014, 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.
 
 library engine.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/src/generated/utilities_general.dart';
@@ skipping 9265 matching lines @@
 
   @override
   ParameterElement get baseElement => super.baseElement as ParameterElement;
 
   @override
   String get defaultValueCode => baseElement.defaultValueCode;
 
   @override
   Element get enclosingElement => baseElement.enclosingElement;
 
+  int get hashCode => baseElement.hashCode;

[Leaf, 2015/11/20 02:09:43]

@override?  Seems to be used elsewhere this is overriden.

[Jennifer Messerly, 2015/11/20 17:09:46]

Done.

+
   @override
   bool get isInitializingFormal => baseElement.isInitializingFormal;
 
   @override
   ParameterKind get parameterKind => baseElement.parameterKind;
 
   @override
   List<ParameterElement> get parameters {
     List<ParameterElement> baseParameters = baseElement.parameters;
     int parameterCount = baseParameters.length;
     if (parameterCount == 0) {
       return baseParameters;
     }
     List<ParameterElement> parameterizedParameters =
         new List<ParameterElement>(parameterCount);
     for (int i = 0; i < parameterCount; i++) {
       parameterizedParameters[i] =
           ParameterMember.from(baseParameters[i], definingType);
     }
     return parameterizedParameters;
   }
 
   @override
   List<TypeParameterElement> get typeParameters => baseElement.typeParameters;
 
   @override
   SourceRange get visibleRange => baseElement.visibleRange;
 
   @override
+  bool operator ==(Object object) =>

[Leaf, 2015/11/20 02:09:43]

Was this a bug?  Why did this need to change?

[Jennifer Messerly, 2015/11/20 17:09:46]

yeah, generally these exist on Elements, and they can be compared for equality.

The bug with ParameterMember: every time you call FunctionTypeImpl.parameters,
it will make new ones, right? Because that's how it works: compute stuff on the
fly. So every time you call that, you get a new set of parameters. Since they
don't compare equal, you can never find what position you came from.

If you have a look over in this file, around line 1718:
https://codereview.chromium.org/1442883003/diff/140001/pkg/analyzer/lib/src/g...

you will notice I'm using .indexOf to find where the corresponding parameter
came from. That's not possible without this fix here.

+      object is ParameterMember && baseElement == object.baseElement;
+
+  @override
   accept(ElementVisitor visitor) => visitor.visitParameterElement(this);
 
   @override
   FormalParameter computeNode() => baseElement.computeNode();
 
   @override
   Element getAncestor(Predicate<Element> predicate) {
     Element element = baseElement.getAncestor(predicate);
     ParameterizedType definingType = this.definingType;
     if (definingType is InterfaceType) {
@@ skipping 1820 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }