new_contents: #!/usr/bin/env python
  #
  # Copyright 2008 Google Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  """Print classes which have a virtual method and non-virtual destructor."""
  
  import sys
  
  from cpp import ast
  from cpp import metrics
  from cpp import utils
  
  
  def _FindWarnings(filename, source, ast_list):
    for node in ast_list:
      if isinstance(node, ast.Class) and node.body:
        class_node = node
        has_virtuals = False
        for node in node.body:
          if (isinstance(node, ast.Function) and
              node.modifiers & ast.FUNCTION_VIRTUAL):
              has_virtuals = True
              if node.modifiers & ast.FUNCTION_DTOR:
                break
        else:
          if has_virtuals and not class_node.bases:
            lines = metrics.Metrics(source)
            print '%s:%d' % (filename, lines.GetLineNumber(class_node.start)),
            print class_node.name, 'has virtual methods without a virtual dtor'
  
  
  def main(argv):
    for filename in argv[1:]:
      source = utils.ReadFile(filename)
      if source is None:
        continue
  
      print 'Processing', filename
      builder = ast.BuilderFromSource(source, filename)
      try:
        entire_ast = filter(None, builder.Generate())
        _FindWarnings(filename, source, entire_ast)
      except:
        # An error message was already printed since we couldn't parse.
        pass
  
  
  if __name__ == '__main__':
    main(sys.argv)
  
subject: Add script to find destructors which are not virtual, but should be