Quick-fix for `annotate_overrides` lint (#25416).

pkg/analysis_server/lib/src/services/correction/fix_internal.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 analysis_server.src.services.correction.fix_internal;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:core' hide Resource;
 
@@ skipping 325 matching lines @@
         errorCode == StaticTypeWarningCode.UNDEFINED_METHOD) {
       _addFix_importLibrary_withFunction();
       _addFix_undefinedMethod_useSimilar();
       _addFix_undefinedMethod_create();
       _addFix_undefinedFunction_create();
     }
     if (errorCode == StaticTypeWarningCode.UNDEFINED_SETTER) {
       _addFix_undefinedClassAccessor_useSimilar();
       _addFix_createField();
     }
+    // lints
+    if (errorCode is LintCode) {
+      if (errorCode.name == LintNames.annotate_overrides) {
+        _addLintFixAddOverrideAnnotation();
+      }
+    }
     // done
     return fixes;
   }
 
   /**
    * Adds a new [SourceEdit] to [change].
    */
   void _addEdit(Element target, SourceEdit edit) {
     if (target == null) {
       target = unitElement;
@@ skipping 1839 matching lines @@
       int delta = sb.length;
       offset += delta;
     }
     // prepare group
     LinkedEditGroup group = _getLinkedPosition(groupId);
     // add position
     Position position = new Position(file, offset);
     group.addPosition(position, range.length);
   }
 
+  void _addLintFixAddOverrideAnnotation() {
+    ClassMember member = node.getAncestor((n) => n is ClassMember);
+    if (member == null) {
+      return;
+    }
+    exitPosition = new Position(file, member.offset - 1);
+    String indent = utils.getIndent(1);
+    _addReplaceEdit(rf.rangeStartLength(member, 0), '@override$eol$indent');
+    _addFix(DartFixKind.LINT_ADD_OVERRIDE, []);
+  }
+
   /**
    * Prepares proposal for creating function corresponding to the given
    * [FunctionType].
    */
   void _addProposal_createFunction(
       FunctionType functionType,
       String name,
       Source targetSource,
       int insertOffset,
       bool isStatic,
@@ skipping 662 matching lines @@
       if (parent is TypeName) {
         return true;
       }
       return _isNameOfType(node.name);
     }
     return false;
   }
 }
 
 /**
+ * An enumeration of lint names.
+ */
+class LintNames {
+  static const String annotate_overrides = 'annotate_overrides';
+}
+
+/**
  * Helper for finding [Element] with name closest to the given.
  */
 class _ClosestElementFinder {
   final String _targetName;
   final ElementPredicate _predicate;
 
   Element _element = null;
   int _distance;
 
   _ClosestElementFinder(this._targetName, this._predicate, this._distance);
@@ skipping 29 matching lines @@
 /**
  * Describes the location for a newly created [FieldDeclaration].
  */
 class _FieldLocation {
   final String prefix;
   final int offset;
   final String suffix;
 
   _FieldLocation(this.prefix, this.offset, this.suffix);
 }