pylint 1.9.x fails on Python 3.7

[jbaum-cmcrc]

There is currently no version of pylint that works on both Python 2.7 and Python 3.7, which are the two "stable" versions.

Steps to reproduce

1. Install pylint==1.9.3 under Python 3.7
2. Create a python module test.py which contains only the statement import datetime
3. Run pylint test.py

Current behavior

An exception is raised, originally in astroid.decorators line 89; full traceback below. This is likely due to the changes introduced in PEP-479 - the current code explicitly raises StopIteration.

Expected behavior

Pylint outputs two messages (missing-docstring and unused-import).

This is the case with pylint 1.9.3 under earlier versions of python, and also the case with the latest pylint under Python 3.7.

pylint --version output

No config file found, using default configuration
pylint 1.9.3,
astroid 1.6.5
Python 3.7.0 (default, Sep 12 2018, 18:30:08)
[GCC 8.0.1 20180414 (experimental) [trunk revision 259383]]

Impact

There is no version of pylint which works under all currently supported versions of Python.

Full traceback

Traceback (most recent call last):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 104, in wrapped
    raise StopIteration
StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/jbaum/qq/venv-37/bin/pylint", line 11, in <module>
    sys.exit(run_pylint())
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/__init__.py", line 16, in run_pylint
    Run(sys.argv[1:])
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/lint.py", line 1353, in __init__
    linter.check(args)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/lint.py", line 774, in check
    self._do_check(files_or_modules)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/lint.py", line 907, in _do_check
    self.check_astroid_module(ast_node, walker, rawcheckers, tokencheckers)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/lint.py", line 986, in check_astroid_module
    walker.walk(ast_node)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/utils.py", line 1014, in walk
    self.walk(child)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/utils.py", line 1011, in walk
    cb(astroid)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/pylint/checkers/variables.py", line 1245, in visit_import
    module = next(node.infer_name_module(parts[0]))
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/context.py", line 71, in cache_generator
    for result in generator:
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/inference.py", line 194, in infer_import
    yield self.do_import_module(name)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/mixins.py", line 119, in do_import_module
    relative_only=level and level >= 1)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 593, in import_module
    return MANAGER.ast_from_module_name(absmodname)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/manager.py", line 154, in ast_from_module_name
    return self.ast_from_file(found_spec.location, modname, fallback=False)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/manager.py", line 80, in ast_from_file
    return AstroidBuilder(self).file_build(filepath, modname)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/builder.py", line 153, in file_build
    return self._post_build(module, encoding)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/builder.py", line 173, in _post_build
    self.delayed_assattr(delayed)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/builder.py", line 232, in delayed_assattr
    for inferred in node.expr.infer():
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/bases.py", line 95, in _infer_stmts
    for inferred in stmt.infer(context=context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/context.py", line 71, in cache_generator
    for result in generator:
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/bases.py", line 95, in _infer_stmts
    for inferred in stmt.infer(context=context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/context.py", line 71, in cache_generator
    for result in generator:
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 142, in raise_if_nothing_inferred
    yield next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/inference.py", line 166, in infer_call
    for callee in self.func.infer(context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/context.py", line 71, in cache_generator
    for result in generator:
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 89, in wrapped
    res = next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/decorators.py", line 142, in raise_if_nothing_inferred
    yield next(generator)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/inference.py", line 259, in infer_attribute
    for obj in owner.igetattr(self.attrname, context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2294, in igetattr
    attrs = self.getattr(name, context, class_context=class_context)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2231, in getattr
    values += self._metaclass_lookup_attribute(name, context)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2247, in _metaclass_lookup_attribute
    attrs.update(set(cls_attributes))
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2253, in _get_attribute_from_metaclass
    class_context=True)
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2227, in getattr
    for classnode in self.ancestors(recurs=True, context=context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 2046, in ancestors
    for baseobj in stmt.infer(context):
  File "/home/jbaum/qq/venv-37/lib/python3.7/site-packages/astroid/context.py", line 71, in cache_generator
    for result in generator:
RuntimeError: generator raised StopIteration

[PCManticore]

@jbaum-cmcrc No, there is not. For 2.7 you need to use 1.9 while for 3.7 you need to use >=2.0. The reason for that is that Python 3.7 support couldn't have been added in pylint without dropping support for Python 2.