Avoid a crash during summary linking when there are inheritance errors.

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

 // 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.
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 36 matching lines @@
   Map<ClassElement, Map<String, ExecutableElement>> _interfaceLookup;
 
   /**
    * A map between each visited [ClassElement] and the set of [AnalysisError]s found on
    * the class element.
    */
   Map<ClassElement, Set<AnalysisError>> _errorsInClassElement =
       new HashMap<ClassElement, Set<AnalysisError>>();
 
   /**
+   * Indicates whether errors should be ignored.

[Brian Wilkerson, 2016/11/29 19:01:51]

Please add an explanation for why we need to not generate the errors in the
first place, given that it's easy for a client to ignore them.

[Paul Berry, 2016/11/29 19:03:45]

Done.

+   */
+  final bool ignoreErrors;
+
+  /**
    * Initialize a newly created inheritance manager.
    *
    * @param library the library element context that the inheritance mappings are being generated
    */
   InheritanceManager(LibraryElement library,
-      {bool includeAbstractFromSuperclasses: false}) {
+      {bool includeAbstractFromSuperclasses: false, this.ignoreErrors: false}) {
     this._library = library;
     _includeAbstractFromSuperclasses = includeAbstractFromSuperclasses;
     _classLookup = new HashMap<ClassElement, Map<String, ExecutableElement>>();
     _interfaceLookup =
         new HashMap<ClassElement, Map<String, ExecutableElement>>();
   }
 
   /**
    * Set the new library element context.
    *
@@ skipping 574 matching lines @@
    * This method is used to report errors on when they are found computing inheritance information.
    * See [ErrorVerifier.checkForInconsistentMethodInheritance] to see where these generated
    * error codes are reported back into the analysis engine.
    *
    * @param classElt the location of the source for which the exception occurred
    * @param offset the offset of the location of the error
    * @param length the length of the location of the error
    * @param errorCode the error code to be associated with this error
    * @param arguments the arguments used to build the error message
    */
-  void _reportError(ClassElement classElt, int offset, int length,
-      ErrorCode errorCode, List<Object> arguments) {
+  void _reportError(
+      ClassElement classElt, ErrorCode errorCode, List<Object> arguments) {
+    if (ignoreErrors) {
+      return;
+    }
     HashSet<AnalysisError> errorSet = _errorsInClassElement[classElt];

[Brian Wilkerson, 2016/11/29 19:01:51]

We could clean this up to use `putIfAbsent`, if you're so inclined.

[Paul Berry, 2016/11/29 19:03:45]

Acknowledged.

     if (errorSet == null) {
       errorSet = new HashSet<AnalysisError>();
       _errorsInClassElement[classElt] = errorSet;
     }
-    errorSet.add(new AnalysisError(
-        classElt.source, offset, length, errorCode, arguments));
+    errorSet.add(new AnalysisError(classElt.source, classElt.nameOffset,
+        classElt.nameLength, errorCode, arguments));
   }
 
   /**
    * Given the set of methods defined by classes above [classElt] in the class hierarchy,
    * apply the appropriate inheritance rules to determine those methods inherited by or overridden
    * by [classElt]. Also report static warnings
    * [StaticTypeWarningCode.INCONSISTENT_METHOD_INHERITANCE] and
    * [StaticWarningCode.INCONSISTENT_METHOD_INHERITANCE_GETTER_AND_METHOD] if appropriate.
    *
    * @param classElt the class element to query.
@@ skipping 110 matching lines @@
               // Example: class A inherited only 2 method named 'm'.
               // One has the function type '() -> int' and one has the function
               // type '() -> String'. Since neither is a subtype of the other,
               // we create a warning, and have this class inherit nothing.
               //
               if (!classHasMember) {
                 String firstTwoFuntionTypesStr =
                     "${executableElementTypes[0]}, ${executableElementTypes[1]}";
                 _reportError(
                     classElt,
-                    classElt.nameOffset,
-                    classElt.nameLength,
                     StaticTypeWarningCode.INCONSISTENT_METHOD_INHERITANCE,
                     [key, firstTwoFuntionTypesStr]);
               }
             } else {
               //
               // Example: class A inherits 2 methods named 'm'.
               // One has the function type '(int) -> dynamic' and one has the
               // function type '(num) -> dynamic'. Since they are both a subtype
               // of the other, a synthetic function '(dynamic) -> dynamic' is
               // inherited.
               // Tests: test_getMapOfMembersInheritedFromInterfaces_
               // union_multipleSubtypes_*
               //
               List<ExecutableElement> elementArrayToMerge =
                   new List<ExecutableElement>(
                       subtypesOfAllOtherTypesIndexes.length);
               for (int i = 0; i < elementArrayToMerge.length; i++) {
                 elementArrayToMerge[i] =
                     elements[subtypesOfAllOtherTypesIndexes[i]];
               }
               ExecutableElement mergedExecutableElement =
                   _computeMergedExecutableElement(elementArrayToMerge);
               resultMap[key] = mergedExecutableElement;
             }
           }
         } else {
           _reportError(
               classElt,
-              classElt.nameOffset,
-              classElt.nameLength,
               StaticWarningCode
                   .INCONSISTENT_METHOD_INHERITANCE_GETTER_AND_METHOD,
               [key]);
         }
       }
     });
     return resultMap;
   }
 
   /**
@@ skipping 403 matching lines @@
   }
 
   /**
    * Initializes [keys] and [values].
    */
   void _initArrays(int initialCapacity) {
     _keys = new List<String>(initialCapacity);
     _values = new List<ExecutableElement>(initialCapacity);
   }
 }