More support for generic function types

pkg/analyzer/lib/src/generated/error_verifier.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 analyzer.src.generated.error_verifier;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1385 matching lines @@
       }
     }
   }
 
   /**
    * Check that all of the parameters have unique names.
    */
   void _checkDuplicateDefinitionInParameterList(FormalParameterList node) {
     Map<String, Element> definedNames = new HashMap<String, Element>();
     for (FormalParameter parameter in node.parameters) {
-      _checkDuplicateIdentifier(definedNames, parameter.identifier);
+      SimpleIdentifier identifier = parameter.identifier;
+      if (identifier != null) {
+        // The identifier can be null if this is a parameter list for a generic
+        // function type.
+        _checkDuplicateIdentifier(definedNames, identifier);
+      }
     }
   }
 
   /**
    * Check that all of the parameters have unique names.
    */
   void _checkDuplicateDefinitionInTypeParameterList(TypeParameterList node) {
     Map<String, Element> definedNames = new HashMap<String, Element>();
     for (TypeParameter parameter in node.typeParameters) {
       _checkDuplicateIdentifier(definedNames, parameter.name);
@@ skipping 5664 matching lines @@
 class _InvocationCollector extends RecursiveAstVisitor {
   final List<String> superCalls = <String>[];
 
   @override
   visitMethodInvocation(MethodInvocation node) {
     if (node.target is SuperExpression) {
       superCalls.add(node.methodName.name);
     }
   }
 }