Fix "if" conditions in summary Builder setters.

pkg/analyzer/tool/summary/generate.dart

 // Copyright (c) 2015, 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.
 
 /**
  * This file contains code to generate serialization/deserialization logic for
  * summaries based on an "IDL" description of the summary format (written in
  * stylized Dart).
  *
  * For each class in the "IDL" input, two corresponding classes are generated:
@@ skipping 314 matching lines @@
             conversion = '$conversion.index';
             condition = ' || _value == ${defaultValue(type)}';
           } else if (_idl.classes.containsKey(type.typeName)) {
             conversion = '$conversion.finish()';
           }
           builderParams.add('${encodedType(type)} $fieldName');
           out('void set $fieldName(${encodedType(type)} _value) {');
           indent(() {
             out('assert(!_finished);');
             out('assert(!_json.containsKey(${quoted(fieldName)}));');
-            out('if (_value != null$condition) {');
+            out('if (!(_value == null$condition)) {');

[Brian Wilkerson, 2015/12/18 18:16:10]

The case where there is no default value got uglier. What would you think of

if (condition.isEmpty) {
  out('if (_value != null) {');
} else {
  out('if (!(_value == null$condition)) {');
}

             indent(() {
               out('_json[${quoted(fieldName)}] = $conversion;');
             });
             out('}');
           });
           out('}');
         });
         if (cls.isTopLevel) {
           out();
           out('List<int> toBuffer() => UTF8.encode(JSON.encode(finish()));');
@@ skipping 22 matching lines @@
     });
   }
 
   /**
    * Enclose [s] in quotes, escaping as necessary.
    */
   String quoted(String s) {
     return JSON.encode(s);
   }
 }