Add ability to look up type parameters that are associated with ClassEntities with the element envi…

pkg/compiler/lib/src/ssa/optimize.dart

 // Copyright (c) 2012, 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 '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart' show Selectors;
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart' show Compiler;
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../common_elements.dart' show CommonElements;
-import '../elements/elements.dart' show ClassElement;
 import '../elements/entities.dart';
 import '../elements/resolution_types.dart';
 import '../elements/types.dart';
 import '../js/js.dart' as js;
 import '../js_backend/backend.dart';
 import '../js_backend/native_data.dart' show NativeData;
 import '../js_backend/runtime_types.dart';
 import '../native/native.dart' as native;
 import '../options.dart';
 import '../types/types.dart';
@@ skipping 1185 matching lines @@
 
       HInstruction source;
       int expectedIndex = 0;
 
       for (HInstruction argument in node.inputs) {
         if (argument is HTypeInfoReadVariable) {
           HInstruction nextSource = argument.object;
           if (nextSource is HThis) {
             if (source == null) {
               source = nextSource;
-              ClassElement contextClass =
+              ClassEntity contextClass =
                   nextSource.sourceElement.enclosingClass;
-              if (node.inputs.length != contextClass.typeVariables.length) {
+              if (node.inputs.length !=
+                  _closedWorld.elementEnvironment
+                      .getTypeVariables(contextClass)
+                      .length) {

[Johnni Winther, 2017/09/04 06:59:56]

If we replace this by

if (node.inputs.length !=
    _closedWorld.elementEnvironment
        .getThisType(contextClass).typeArguments.length) {

we can avoid the need for the [getTypeVariables] method.

It might be worth having it as a convenience method, though.

[Emily Fortuna, 2017/09/05 17:13:31]

ah, my mistake. I misunderstood the distinction between typeArguments and type
parameters. Thank you.

                 return null;
               }
               if (needsSubstitutionForTypeVariableAccess(contextClass)) {
                 return null;
               }
             }
             if (nextSource != source) return null;
             // Check that the index is the one we expect.
             int index = argument.variable.element.index;
             if (index != expectedIndex++) return null;
@@ skipping 1754 matching lines @@
 
     keyedValues.forEach((receiver, values) {
       result.keyedValues[receiver] =
           new Map<HInstruction, HInstruction>.from(values);
     });
 
     result.nonEscapingReceivers.addAll(nonEscapingReceivers);
     return result;
   }
 }