Fix for false positive in field (not-)overriding.

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

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 8b583239440b30e4cd1d90517f083dc7cfe9abe2..9c78da091b308c633fee69ec44ccd5dc898c594d 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -5141,7 +5141,7 @@ class InstanceFieldResolverVisitor extends ResolverVisitor {
  * Instances of the class `OverrideVerifier` visit all of the declarations in a compilation
  * unit to verify that if they have an override annotation it is being used correctly.
  */
-class OverrideVerifier extends RecursiveAstVisitor<Object> {
+class OverrideVerifier extends RecursiveAstVisitor {
   /**
    * The error reporter used to report errors.
    */
@@ -5161,22 +5161,23 @@ class OverrideVerifier extends RecursiveAstVisitor<Object> {
   OverrideVerifier(this._errorReporter, this._manager);
 
   @override
-  Object visitFieldDeclaration(FieldDeclaration node) {
+  visitFieldDeclaration(FieldDeclaration node) {
     for (VariableDeclaration field in node.fields.variables) {
       VariableElement fieldElement = field.element;
       if (fieldElement is FieldElement && _isOverride(fieldElement)) {
-        PropertyAccessorElement getterElement = fieldElement.getter;
-        if (_getOverriddenMember(getterElement) == null) {
+        PropertyAccessorElement getter = fieldElement.getter;
+        PropertyAccessorElement setter = fieldElement.setter;
+        if (!(_getOverriddenMember(getter) != null ||

[pquitslund, 2016/07/26 05:32:49]

Is it possible for `getter` to be null here?  Do we need to test?

[scheglov, 2016/07/26 05:48:23]

If other parts of analyzer work correctly, there should always be `getter`.
But maybe we should check anyway...

[Brian Wilkerson, 2016/07/27 14:24:41]

I'd rather that we just make other parts of analyzer work correctly...

+            setter != null && _getOverriddenMember(setter) != null)) {
           _errorReporter.reportErrorForNode(
-              HintCode.OVERRIDE_ON_NON_OVERRIDING_GETTER, field.name);
+              HintCode.OVERRIDE_ON_NON_OVERRIDING_FIELD, field.name);
         }
       }
     }
-    return super.visitFieldDeclaration(node);
   }
 
   @override
-  Object visitMethodDeclaration(MethodDeclaration node) {
+  visitMethodDeclaration(MethodDeclaration node) {
     ExecutableElement element = node.element;
     if (_isOverride(element)) {
       if (_getOverriddenMember(element) == null) {
@@ -5194,7 +5195,6 @@ class OverrideVerifier extends RecursiveAstVisitor<Object> {
         }
       }
     }
-    return super.visitMethodDeclaration(node);
   }
 
   /**