Enable the new analysis driver by default, use --disable-new-analysis-driver to disable.

pkg/analysis_server/lib/src/server/driver.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 driver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 224 matching lines @@
   static const String INCREMENTAL_RESOLUTION_LOG = "incremental-resolution-log";
 
   /**
    * The name of the option used to enable validation of incremental resolution
    * results.
    */
   static const String INCREMENTAL_RESOLUTION_VALIDATION =
       "incremental-resolution-validation";
 
   /**
-   * The name of the option used to enable using the new analysis driver.
+   * The name of the option used to disable using the new analysis driver.
    */
-  static const String ENABLE_NEW_ANALYSIS_DRIVER = 'enable-new-analysis-driver';
+  static const String DISABLE_NEW_ANALYSIS_DRIVER =
+      'disable-new-analysis-driver';

[devoncarew, 2017/01/03 19:40:59]

Does the analysis server ignore arguments is doesn't understand? Some few
clients will be passing in --enable-new-analysis-driver.

 
   /**
    * The name of the option used to enable using pub summary manager.
    */
   static const String ENABLE_PUB_SUMMARY_MANAGER = 'enable-pub-summary-manager';
 
   /**
    * The name of the option used to enable fined grained invalidation.
    */
   static const String FINER_GRAINED_INVALIDATION = 'finer-grained-invalidation';
@@ skipping 128 matching lines @@
         return;
       }
     }
 
     AnalysisServerOptions analysisServerOptions = new AnalysisServerOptions();
     analysisServerOptions.enableIncrementalResolutionApi =
         results[ENABLE_INCREMENTAL_RESOLUTION_API];
     analysisServerOptions.enableIncrementalResolutionValidation =
         results[INCREMENTAL_RESOLUTION_VALIDATION];
     analysisServerOptions.enableNewAnalysisDriver =
-        results[ENABLE_NEW_ANALYSIS_DRIVER];
+        !results[DISABLE_NEW_ANALYSIS_DRIVER];
     analysisServerOptions.enablePubSummaryManager =
         results[ENABLE_PUB_SUMMARY_MANAGER];
     analysisServerOptions.finerGrainedInvalidation =
         results[FINER_GRAINED_INVALIDATION];
     analysisServerOptions.noErrorNotification = results[NO_ERROR_NOTIFICATION];
     analysisServerOptions.noIndex = results[NO_INDEX];
     analysisServerOptions.useAnalysisHighlight2 =
         results[USE_ANALISYS_HIGHLIGHT2];
     analysisServerOptions.fileReadMode = results[FILE_READ_MODE];
     analysisServerOptions.newAnalysisDriverLog =
@@ skipping 129 matching lines @@
     parser.addFlag(HELP_OPTION,
         help: "print this help message without starting a server",
         defaultsTo: false,
         negatable: false);
     parser.addOption(INCREMENTAL_RESOLUTION_LOG,
         help: "set a destination for the incremental resolver's log");
     parser.addFlag(INCREMENTAL_RESOLUTION_VALIDATION,
         help: "enable validation of incremental resolution results (slow)",
         defaultsTo: false,
         negatable: false);
-    parser.addFlag(ENABLE_NEW_ANALYSIS_DRIVER,
-        help: "enable using new analysis driver",
+    parser.addFlag(DISABLE_NEW_ANALYSIS_DRIVER,
+        help: "disable using new analysis driver",
         defaultsTo: false,
         negatable: false);
     parser.addFlag(ENABLE_PUB_SUMMARY_MANAGER,
         help: "enable using summaries for pub cache packages",
         defaultsTo: false,
         negatable: false);
     parser.addFlag(FINER_GRAINED_INVALIDATION,
         help: "enable finer grained invalidation",
         defaultsTo: false,
         negatable: false);
@@ skipping 96 matching lines @@
    */
   static void _rollLogFiles(String path, int numOld) {
     for (int i = numOld - 1; i >= 0; i--) {
       try {
         String oldPath = i == 0 ? path : '$path.$i';
         new File(oldPath).renameSync('$path.${i+1}');
       } catch (e) {}
     }
   }
 }