Python 3.4 breaks Function Argument Name checking

[kdopen]

Looks like something in the AST modules change in python 3.4

• In python 3.3, node.args.kwargs returns <class 'str'>
• In python 3.4, node.args.kwargs returns <class '_ast.arg'>

This breaks FunctionArgNamesCheck.visit_functiondef() at line 187 when the return value is passed to LOWERCASE_REGEX.match() which expects a string value.

A simple test file with the following contents:

def _foo(*popenargs, **kwargs):
    pass

Will produce the following exception trace when run with python 3.4

Traceback (most recent call last):
  File "/home/keith/.virtualenvs/play34/bin/flake8", line 9, in <module>
    load_entry_point('flake8==2.1.0', 'console_scripts', 'flake8')()
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/flake8/main.py", line 32, in main
    report = flake8_style.check_files()
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8.py", line 1624, in check_files
    runner(path)
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/flake8/engine.py", line 73, in input_file
    return fchecker.check_all(expected=expected, line_offset=line_offset)
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8.py", line 1366, in check_all
    self.check_ast()
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8.py", line 1346, in check_ast
    for lineno, offset, text, check in checker.run():
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8ext_naming.py", line 78, in visit_tree
    for error in self.visit_tree(child):
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8ext_naming.py", line 74, in visit_tree
    for error in self.visit_node(node):
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8ext_naming.py", line 92, in visit_node
    for error in getattr(visitor, method)(node, self.parents):
  File "/home/keith/.virtualenvs/play34/lib/python3.4/site-packages/pep8ext_naming.py", line 188, in visit_functiondef
    if not self.check(node.args.kwarg):
TypeError: expected string or buffer

System info:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.4 LTS
Release:    12.04
Codename:   precise
$ python --version
Python 3.4.0
$ pip freeze
flake8==2.1.0
ipython==1.2.1
mccabe==0.2.1
pep8==1.4.6
pep8-naming==0.2.1
pyflakes==0.8

Originally seen on OSX 10.9.1

[kdopen]

been playing with it. In ipython I see the following:

In [49]: s=ast.parse('def foo(*args,**kwargs): pass')

In [50]: class V(ast.NodeVisitor):
    def visit_FunctionDef(self,node):
        print (node.__dict__)
        print(node.args.__dict__)
        print(node.args.kwarg.__dict__)

In [51]: V().visit(s.body[0])
{'body': [<_ast.Pass object at 0xb5ee650c>], 'lineno': 1, 'decorator_list': [], 'args': <_ast.arguments object at 0xb5ee64ac>, 'returns': None, 'name': 'foo', 'col_offset': 0}
{'defaults': [], 'kwonlyargs': [], 'args': [], 'vararg': <_ast.arg object at 0xb5ee64cc>, 'kwarg': <_ast.arg object at 0xb5ee64ec>, 'kw_defaults': []}
{'arg': 'kwargs', 'lineno': 1, 'annotation': None, 'col_offset': 16}

So it looks like you need node.args.kwarg.arg to get the name of the argument

[kdopen]

Think you might find the same issue with node.args.args and node.args.vararg looking at this:

In [69]: s=ast.parse('def foo(normal, *args,**kwargs): pass')

In [70]: for n in ast.walk(s): pprint({ 'class':type(n), 'repr':repr(n), 'name':n.__class__.__name__, 'dict':n.__dict__})
{'class': <class '_ast.Module'>,
 'dict': {'body': [<_ast.FunctionDef object at 0xb5ee05ec>]},
 'name': 'Module',
 'repr': '<_ast.Module object at 0xb5ee05cc>'}
{'class': <class '_ast.FunctionDef'>,
 'dict': {'args': <_ast.arguments object at 0xb5ee060c>,
          'body': [<_ast.Pass object at 0xb5ee066c>],
          'col_offset': 0,
          'decorator_list': [],
          'lineno': 1,
          'name': 'foo',
          'returns': None},
 'name': 'FunctionDef',
 'repr': '<_ast.FunctionDef object at 0xb5ee05ec>'}
{'class': <class '_ast.arguments'>,
 'dict': {'args': [<_ast.arg object at 0xb5ee062c>],
          'defaults': [],
          'kw_defaults': [],
          'kwarg': <_ast.arg object at 0xb5ee048c>,
          'kwonlyargs': [],
          'vararg': <_ast.arg object at 0xb5ee064c>},
 'name': 'arguments',
 'repr': '<_ast.arguments object at 0xb5ee060c>'}
{'class': <class '_ast.Pass'>,
 'dict': {'col_offset': 33, 'lineno': 1},
 'name': 'Pass',
 'repr': '<_ast.Pass object at 0xb5ee066c>'}
{'class': <class '_ast.arg'>,
 'dict': {'annotation': None, 'arg': 'normal', 'col_offset': 8, 'lineno': 1},
 'name': 'arg',
 'repr': '<_ast.arg object at 0xb5ee062c>'}
{'class': <class '_ast.arg'>,
 'dict': {'annotation': None, 'arg': 'args', 'col_offset': 17, 'lineno': 1},
 'name': 'arg',
 'repr': '<_ast.arg object at 0xb5ee064c>'}
{'class': <class '_ast.arg'>,
 'dict': {'annotation': None, 'arg': 'kwargs', 'col_offset': 24, 'lineno': 1},
 'name': 'arg',
 'repr': '<_ast.arg object at 0xb5ee048c>'}

In [71]: 

[kdopen]

Closed in PR #13