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

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

Index: pkg/analyzer/lib/src/dart/resolver/inheritance_manager.dart
diff --git a/pkg/analyzer/lib/src/dart/resolver/inheritance_manager.dart b/pkg/analyzer/lib/src/dart/resolver/inheritance_manager.dart
index 57c416912aaca0b7c5c5314d4dd2fa8225bfe1a3..a6300f8aff19610386c1a58e049a367507126888 100644
--- a/pkg/analyzer/lib/src/dart/resolver/inheritance_manager.dart
+++ b/pkg/analyzer/lib/src/dart/resolver/inheritance_manager.dart
@@ -54,12 +54,17 @@ class InheritanceManager {
       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>>();
@@ -654,15 +659,18 @@ class InheritanceManager {
    * @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));
   }
 
   /**
@@ -793,8 +801,6 @@ class InheritanceManager {
                     "${executableElementTypes[0]}, ${executableElementTypes[1]}";
                 _reportError(
                     classElt,
-                    classElt.nameOffset,
-                    classElt.nameLength,
                     StaticTypeWarningCode.INCONSISTENT_METHOD_INHERITANCE,
                     [key, firstTwoFuntionTypesStr]);
               }
@@ -823,8 +829,6 @@ class InheritanceManager {
         } else {
           _reportError(
               classElt,
-              classElt.nameOffset,
-              classElt.nameLength,
               StaticWarningCode
                   .INCONSISTENT_METHOD_INHERITANCE_GETTER_AND_METHOD,
               [key]);