anchor.diff:      }
   
       // Read the unlinked bundle.
  -    var driverUnlinkedUnit = new AnalysisDriverUnlinkedUnit.fromBuffer(bytes);
  -    _definedTopLevelNames = driverUnlinkedUnit.definedTopLevelNames.toSet();
  -    _definedClassMemberNames =
  -        driverUnlinkedUnit.definedClassMemberNames.toSet();
  -    _referencedNames = driverUnlinkedUnit.referencedNames.toSet();
  -    _subtypedNames = driverUnlinkedUnit.subtypedNames.toSet();
  -    _unlinked = driverUnlinkedUnit.unit;
  +    _driverUnlinkedUnit = new AnalysisDriverUnlinkedUnit.fromBuffer(bytes);
  +    _unlinked = _driverUnlinkedUnit.unit;
       _lineInfo = new LineInfo(_unlinked.lineStarts);
  +
  +    // Invalidate unlinked information.
  +    _definedTopLevelNames = null;
  +    _definedClassMemberNames = null;
  +    _referencedNames = null;
  +    _subtypedNames = null;
       _topLevelDeclarations = null;
   
       // Prepare API signature.
  
positive.code:   String _content;
    String _contentHash;
    LineInfo _lineInfo;
    Set<String> _definedTopLevelNames;
    Set<String> _definedClassMemberNames;
    Set<String> _referencedNames;
    Set<String> _subtypedNames;
    String _unlinkedKey;
    UnlinkedUnit _unlinked;
    List<int> _apiSignature;
  
  
negative.code:   /**
     * The class member names defined by the file.
     */
    Set<String> get definedClassMemberNames {
      return _definedClassMemberNames ??=
          _driverUnlinkedUnit.definedClassMemberNames.toSet();
    }
  
    /**
     * The top-level names defined by the file.
     */
    Set<String> get definedTopLevelNames {
      return _definedTopLevelNames ??=
          _driverUnlinkedUnit.definedTopLevelNames.toSet();
    }
  
    /**
     * Return the set of all directly referenced files - imported, exported or
  