# Copyright (c) 2006-2013 LOGILAB S.A. (Paris, FRANCE). # http://www.logilab.fr/ -- mailto:contact@logilab.fr # # This program is free software; you can redistribute it and/or modify it under # the terms of the GNU General Public License as published by the Free Software # Foundation; either version 2 of the License, or (at your option) any later # version. # # This program is distributed in the hope that it will be useful, but WITHOUT # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS # FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. # # You should have received a copy of the GNU General Public License along with # this program; if not, write to the Free Software Foundation, Inc., # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. """try to find more bugs in the code using astroid inference capabilities """ import collections import fnmatch import re import shlex import sys import six import astroid import astroid.context import astroid.arguments from astroid import exceptions from astroid import objects from astroid import bases from pylint.interfaces import IAstroidChecker, INFERENCE, INFERENCE_FAILURE from pylint.checkers import BaseChecker from pylint.checkers.utils import ( is_super, check_messages, decorated_with_property, decorated_with, node_ignores_exception, is_iterable, is_mapping, supports_membership_test, is_comprehension, is_inside_abstract_class, supports_subscript, safe_infer, has_known_bases) from pylint import utils _ZOPE_DEPRECATED = ( "This option is deprecated. Use generated-members instead." ) BUILTINS = six.moves.builtins.__name__ STR_FORMAT = "%s.str.format" % BUILTINS def _unflatten(iterable): for index, elem in enumerate(iterable): if (isinstance(elem, collections.Sequence) and not isinstance(elem, six.string_types)): for elem in _unflatten(elem): yield elem elif elem and not index: # We're interested only in the first element. yield elem def _is_owner_ignored(owner, name, ignored_classes, ignored_modules): """Check if the given owner should be ignored This will verify if the owner's module is in *ignored_modules* or the owner's module fully qualified name is in *ignored_modules* or if the *ignored_modules* contains a pattern which catches the fully qualified name of the module. Also, similar checks are done for the owner itself, if its name matches any name from the *ignored_classes* or if its qualified name can be found in *ignored_classes*. """ ignored_modules = set(ignored_modules) module_name = owner.root().name module_qname = owner.root().qname() if any(module_name in ignored_modules or module_qname in ignored_modules or fnmatch.fnmatch(module_qname, ignore) for ignore in ignored_modules): return True ignored_classes = set(ignored_classes) if hasattr(owner, 'qname'): qname = owner.qname() else: qname = '' return any(name == ignore or qname == ignore for ignore in ignored_classes) MSGS = { 'E1101': ('%s %r has no %r member', 'no-member', 'Used when a variable is accessed for an unexistent member.', {'old_names': [('E1103', 'maybe-no-member')]}), 'E1102': ('%s is not callable', 'not-callable', 'Used when an object being called has been inferred to a non \ callable object'), 'E1111': ('Assigning to function call which doesn\'t return', 'assignment-from-no-return', 'Used when an assignment is done on a function call but the \ inferred function doesn\'t return anything.'), 'E1120': ('No value for argument %s in %s call', 'no-value-for-parameter', 'Used when a function call passes too few arguments.'), 'E1121': ('Too many positional arguments for %s call', 'too-many-function-args', 'Used when a function call passes too many positional \ arguments.'), 'E1123': ('Unexpected keyword argument %r in %s call', 'unexpected-keyword-arg', 'Used when a function call passes a keyword argument that \ doesn\'t correspond to one of the function\'s parameter names.'), 'E1124': ('Argument %r passed by position and keyword in %s call', 'redundant-keyword-arg', 'Used when a function call would result in assigning multiple \ values to a function parameter, one value from a positional \ argument and one from a keyword argument.'), 'E1125': ('Missing mandatory keyword argument %r in %s call', 'missing-kwoa', ('Used when a function call does not pass a mandatory' ' keyword-only argument.'), {'minversion': (3, 0)}), 'E1126': ('Sequence index is not an int, slice, or instance with __index__', 'invalid-sequence-index', 'Used when a sequence type is indexed with an invalid type. ' 'Valid types are ints, slices, and objects with an __index__ ' 'method.'), 'E1127': ('Slice index is not an int, None, or instance with __index__', 'invalid-slice-index', 'Used when a slice index is not an integer, None, or an object \ with an __index__ method.'), 'E1128': ('Assigning to function call which only returns None', 'assignment-from-none', 'Used when an assignment is done on a function call but the ' 'inferred function returns nothing but None.', {'old_names': [('W1111', 'assignment-from-none')]}), 'E1129': ("Context manager '%s' doesn't implement __enter__ and __exit__.", 'not-context-manager', 'Used when an instance in a with statement doesn\'t implement ' 'the context manager protocol(__enter__/__exit__).'), 'E1130': ('%s', 'invalid-unary-operand-type', 'Emitted when an unary operand is used on an object which does not ' 'support this type of operation'), 'E1131': ('%s', 'unsupported-binary-operation', 'Emitted when a binary arithmetic operation between two ' 'operands is not supported.'), 'E1132': ('Got multiple values for keyword argument %r in function call', 'repeated-keyword', 'Emitted when a function call got multiple values for a keyword.'), 'E1135': ("Value '%s' doesn't support membership test", 'unsupported-membership-test', 'Emitted when an instance in membership test expression doesn\'t' 'implement membership protocol (__contains__/__iter__/__getitem__)'), 'E1136': ("Value '%s' is unsubscriptable", 'unsubscriptable-object', "Emitted when a subscripted value doesn't support subscription" "(i.e. doesn't define __getitem__ method)"), } # builtin sequence types in Python 2 and 3. SEQUENCE_TYPES = set(['str', 'unicode', 'list', 'tuple', 'bytearray', 'xrange', 'range', 'bytes', 'memoryview']) def _emit_no_member(node, owner, owner_name, ignored_mixins): """Try to see if no-member should be emitted for the given owner. The following cases are ignored: * the owner is a function and it has decorators. * the owner is an instance and it has __getattr__, __getattribute__ implemented * the module is explicitly ignored from no-member checks * the owner is a class and the name can be found in its metaclass. * The access node is protected by an except handler, which handles AttributeError, Exception or bare except. """ if node_ignores_exception(node, AttributeError): return False # skip None anyway if isinstance(owner, astroid.Const) and owner.value is None: return False if is_super(owner) or getattr(owner, 'type', None) == 'metaclass': return False if ignored_mixins and owner_name[-5:].lower() == 'mixin': return False if isinstance(owner, astroid.FunctionDef) and owner.decorators: return False if isinstance(owner, astroid.Instance): if owner.has_dynamic_getattr() or not has_known_bases(owner): return False if isinstance(owner, objects.Super): # Verify if we are dealing with an invalid Super object. # If it is invalid, then there's no point in checking that # it has the required attribute. Also, don't fail if the # MRO is invalid. try: owner.super_mro() except (exceptions.MroError, exceptions.SuperError): return False if not all(map(has_known_bases, owner.type.mro())): return False return True def _determine_callable(callable_obj): # Ordering is important, since BoundMethod is a subclass of UnboundMethod, # and Function inherits Lambda. if isinstance(callable_obj, astroid.BoundMethod): # Bound methods have an extra implicit 'self' argument. return callable_obj, 1, callable_obj.type elif isinstance(callable_obj, astroid.UnboundMethod): return callable_obj, 0, 'unbound method' elif isinstance(callable_obj, astroid.FunctionDef): return callable_obj, 0, callable_obj.type elif isinstance(callable_obj, astroid.Lambda): return callable_obj, 0, 'lambda' elif isinstance(callable_obj, astroid.ClassDef): # Class instantiation, lookup __new__ instead. # If we only find object.__new__, we can safely check __init__ # instead. If __new__ belongs to builtins, then we look # again for __init__ in the locals, since we won't have # argument information for the builtin __new__ function. try: # Use the last definition of __new__. new = callable_obj.local_attr('__new__')[-1] except exceptions.NotFoundError: new = None from_object = new and new.parent.scope().name == 'object' from_builtins = new and new.root().name in sys.builtin_module_names if not new or from_object or from_builtins: try: # Use the last definition of __init__. callable_obj = callable_obj.local_attr('__init__')[-1] except exceptions.NotFoundError: # do nothing, covered by no-init. raise ValueError else: callable_obj = new if not isinstance(callable_obj, astroid.FunctionDef): raise ValueError # both have an extra implicit 'cls'/'self' argument. return callable_obj, 1, 'constructor' else: raise ValueError class TypeChecker(BaseChecker): """try to find bugs in the code using type inference """ __implements__ = (IAstroidChecker,) # configuration section name name = 'typecheck' # messages msgs = MSGS priority = -1 # configuration options options = (('ignore-mixin-members', {'default' : True, 'type' : 'yn', 'metavar': '', 'help' : 'Tells whether missing members accessed in mixin \ class should be ignored. A mixin class is detected if its name ends with \ "mixin" (case insensitive).'} ), ('ignored-modules', {'default': (), 'type': 'csv', 'metavar': '', 'help': 'List of module names for which member attributes ' 'should not be checked (useful for modules/projects ' 'where namespaces are manipulated during runtime and ' 'thus existing member attributes cannot be ' 'deduced by static analysis. It supports qualified ' 'module names, as well as Unix pattern matching.'} ), ('ignored-classes', {'default' : (), 'type' : 'csv', 'metavar' : '', 'help' : 'List of classes names for which member attributes ' 'should not be checked (useful for classes with ' 'attributes dynamically set). This supports ' 'can work with qualified names.'} ), ('zope', utils.deprecated_option(opt_type='yn', help_msg=_ZOPE_DEPRECATED)), ('generated-members', {'default' : (), 'type' : 'string', 'metavar' : '', 'help' : 'List of members which are set dynamically and \ missed by pylint inference system, and so shouldn\'t trigger E1101 when \ accessed. Python regular expressions are accepted.'} ), ) def open(self): # do this in open since config not fully initialized in __init__ # generated_members may contain regular expressions # (surrounded by quote `"` and followed by a comma `,`) # REQUEST,aq_parent,"[a-zA-Z]+_set{1,2}"' => # ('REQUEST', 'aq_parent', '[a-zA-Z]+_set{1,2}') if isinstance(self.config.generated_members, six.string_types): gen = shlex.shlex(self.config.generated_members) gen.whitespace += ',' gen.wordchars += '[]-+' self.config.generated_members = tuple(tok.strip('"') for tok in gen) def visit_assignattr(self, node): if isinstance(node.assign_type(), astroid.AugAssign): self.visit_attribute(node) def visit_delattr(self, node): self.visit_attribute(node) @check_messages('no-member') def visit_attribute(self, node): """check that the accessed attribute exists to avoid too much false positives for now, we'll consider the code as correct if a single of the inferred nodes has the accessed attribute. function/method, super call and metaclasses are ignored """ for pattern in self.config.generated_members: # attribute is marked as generated, stop here if re.match(pattern, node.attrname): return try: infered = list(node.expr.infer()) except exceptions.InferenceError: return # list of (node, nodename) which are missing the attribute missingattr = set() inference_failure = False for owner in infered: # skip yes object if owner is astroid.YES: inference_failure = True continue name = getattr(owner, 'name', None) if _is_owner_ignored(owner, name, self.config.ignored_classes, self.config.ignored_modules): continue try: if not [n for n in owner.getattr(node.attrname) if not isinstance(n.statement(), astroid.AugAssign)]: missingattr.add((owner, name)) continue except AttributeError: # XXX method / function continue except exceptions.NotFoundError: # This can't be moved before the actual .getattr call, # because there can be more values inferred and we are # stopping after the first one which has the attribute in question. # The problem is that if the first one has the attribute, # but we continue to the next values which doesn't have the # attribute, then we'll have a false positive. # So call this only after the call has been made. if not _emit_no_member(node, owner, name, self.config.ignore_mixin_members): continue missingattr.add((owner, name)) continue # stop on the first found break else: # we have not found any node with the attributes, display the # message for infered nodes done = set() for owner, name in missingattr: if isinstance(owner, astroid.Instance): actual = owner._proxied else: actual = owner if actual in done: continue done.add(actual) confidence = INFERENCE if not inference_failure else INFERENCE_FAILURE self.add_message('no-member', node=node, args=(owner.display_type(), name, node.attrname), confidence=confidence) @check_messages('assignment-from-no-return', 'assignment-from-none') def visit_assign(self, node): """check that if assigning to a function call, the function is possibly returning something valuable """ if not isinstance(node.value, astroid.Call): return function_node = safe_infer(node.value.func) # skip class, generator and incomplete function definition if not (isinstance(function_node, astroid.FunctionDef) and function_node.root().fully_defined()): return if function_node.is_generator() \ or function_node.is_abstract(pass_is_abstract=False): return returns = list(function_node.nodes_of_class(astroid.Return, skip_klass=astroid.FunctionDef)) if len(returns) == 0: self.add_message('assignment-from-no-return', node=node) else: for rnode in returns: if not (isinstance(rnode.value, astroid.Const) and rnode.value.value is None or rnode.value is None): break else: self.add_message('assignment-from-none', node=node) def _check_uninferable_callfunc(self, node): """ Check that the given uninferable CallFunc node does not call an actual function. """ if not isinstance(node.func, astroid.Attribute): return # Look for properties. First, obtain # the lhs of the Getattr node and search the attribute # there. If that attribute is a property or a subclass of properties, # then most likely it's not callable. # TODO: since astroid doesn't understand descriptors very well # we will not handle them here, right now. expr = node.func.expr klass = safe_infer(expr) if (klass is None or klass is astroid.YES or not isinstance(klass, astroid.Instance)): return try: attrs = klass._proxied.getattr(node.func.attrname) except exceptions.NotFoundError: return for attr in attrs: if attr is astroid.YES: continue if not isinstance(attr, astroid.FunctionDef): continue # Decorated, see if it is decorated with a property. # Also, check the returns and see if they are callable. if decorated_with_property(attr): if all(return_node.callable() for return_node in attr.infer_call_result(node)): continue else: self.add_message('not-callable', node=node, args=node.func.as_string()) break @staticmethod def _no_context_variadic(node): """Verify if the given call node has variadic nodes without context This is a workaround for handling cases of nested call functions which don't have the specific call context at hand. Variadic arguments (variable positional arguments and variable keyword arguments) are inferred, inherently wrong, by astroid as a Tuple, respectively a Dict with empty elements. This can lead pylint to believe that a function call receives too few arguments. """ for arg in node.args: if not isinstance(arg, astroid.Starred): continue inferred = safe_infer(arg.value) if isinstance(inferred, astroid.Tuple): length = len(inferred.elts) elif isinstance(inferred, astroid.Dict): length = len(inferred.items) else: return False if not length and isinstance(inferred.statement(), astroid.FunctionDef): return True return False @check_messages(*(list(MSGS.keys()))) def visit_call(self, node): """check that called functions/methods are inferred to callable objects, and that the arguments passed to the function match the parameters in the inferred function's definition """ # Build the set of keyword arguments, checking for duplicate keywords, # and count the positional arguments. call_site = astroid.arguments.CallSite.from_call(node) num_positional_args = len(call_site.positional_arguments) keyword_args = list(call_site.keyword_arguments.keys()) no_context_variadic = self._no_context_variadic(node) called = safe_infer(node.func) # only function, generator and object defining __call__ are allowed if called is not None and not called.callable(): self.add_message('not-callable', node=node, args=node.func.as_string()) self._check_uninferable_callfunc(node) try: called, implicit_args, callable_name = _determine_callable(called) except ValueError: # Any error occurred during determining the function type, most of # those errors are handled by different warnings. return num_positional_args += implicit_args if called.args.args is None: # Built-in functions have no argument information. return if len(called.argnames()) != len(set(called.argnames())): # Duplicate parameter name (see duplicate-argument). We can't really # make sense of the function call in this case, so just return. return # Warn about duplicated keyword arguments, such as `f=24, **{'f': 24}` for keyword in call_site.duplicated_keywords: self.add_message('repeated-keyword', node=node, args=(keyword, )) if call_site.has_invalid_arguments() or call_site.has_invalid_keywords(): # Can't make sense of this. return # Analyze the list of formal parameters. num_mandatory_parameters = len(called.args.args) - len(called.args.defaults) parameters = [] parameter_name_to_index = {} for i, arg in enumerate(called.args.args): if isinstance(arg, astroid.Tuple): name = None # Don't store any parameter names within the tuple, since those # are not assignable from keyword arguments. else: assert isinstance(arg, astroid.AssignName) # This occurs with: # def f( (a), (b) ): pass name = arg.name parameter_name_to_index[name] = i if i >= num_mandatory_parameters: defval = called.args.defaults[i - num_mandatory_parameters] else: defval = None parameters.append([(name, defval), False]) kwparams = {} for i, arg in enumerate(called.args.kwonlyargs): if isinstance(arg, astroid.Keyword): name = arg.arg else: assert isinstance(arg, astroid.AssignName) name = arg.name kwparams[name] = [called.args.kw_defaults[i], False] # Match the supplied arguments against the function parameters. # 1. Match the positional arguments. for i in range(num_positional_args): if i < len(parameters): parameters[i][1] = True elif called.args.vararg is not None: # The remaining positional arguments get assigned to the *args # parameter. break else: # Too many positional arguments. self.add_message('too-many-function-args', node=node, args=(callable_name,)) break # 2. Match the keyword arguments. for keyword in keyword_args: if keyword in parameter_name_to_index: i = parameter_name_to_index[keyword] if parameters[i][1]: # Duplicate definition of function parameter. # Might be too hardcoded, but this can actually # happen when using str.format and `self` is passed # by keyword argument, as in `.format(self=self)`. # It's perfectly valid to so, so we're just skipping # it if that's the case. if not (keyword == 'self' and called.qname() == STR_FORMAT): self.add_message('redundant-keyword-arg', node=node, args=(keyword, callable_name)) else: parameters[i][1] = True elif keyword in kwparams: if kwparams[keyword][1]: # XXX is that even possible? # Duplicate definition of function parameter. self.add_message('redundant-keyword-arg', node=node, args=(keyword, callable_name)) else: kwparams[keyword][1] = True elif called.args.kwarg is not None: # The keyword argument gets assigned to the **kwargs parameter. pass else: # Unexpected keyword argument. self.add_message('unexpected-keyword-arg', node=node, args=(keyword, callable_name)) # 3. Match the **kwargs, if any. if node.kwargs: for i, [(name, defval), assigned] in enumerate(parameters): # Assume that *kwargs provides values for all remaining # unassigned named parameters. if name is not None: parameters[i][1] = True else: # **kwargs can't assign to tuples. pass # Check that any parameters without a default have been assigned # values. for [(name, defval), assigned] in parameters: if (defval is None) and not assigned: if name is None: display_name = '' else: display_name = repr(name) # TODO(cpopa): this should be removed after PyCQA/astroid/issues/177 if not no_context_variadic: self.add_message('no-value-for-parameter', node=node, args=(display_name, callable_name)) for name in kwparams: defval, assigned = kwparams[name] if defval is None and not assigned: self.add_message('missing-kwoa', node=node, args=(name, callable_name)) @check_messages('invalid-sequence-index') def visit_extslice(self, node): # Check extended slice objects as if they were used as a sequence # index to check if the object being sliced can support them return self.visit_index(node) @check_messages('invalid-sequence-index') def visit_index(self, node): if not node.parent or not hasattr(node.parent, "value"): return # Look for index operations where the parent is a sequence type. # If the types can be determined, only allow indices to be int, # slice or instances with __index__. parent_type = safe_infer(node.parent.value) if not isinstance(parent_type, (astroid.ClassDef, astroid.Instance)): return # Determine what method on the parent this index will use # The parent of this node will be a Subscript, and the parent of that # node determines if the Subscript is a get, set, or delete operation. operation = node.parent.parent if isinstance(operation, astroid.Assign): methodname = '__setitem__' elif isinstance(operation, astroid.Delete): methodname = '__delitem__' else: methodname = '__getitem__' # Check if this instance's __getitem__, __setitem__, or __delitem__, as # appropriate to the statement, is implemented in a builtin sequence # type. This way we catch subclasses of sequence types but skip classes # that override __getitem__ and which may allow non-integer indices. try: methods = parent_type.getattr(methodname) if methods is astroid.YES: return itemmethod = methods[0] except (exceptions.NotFoundError, IndexError): return if not isinstance(itemmethod, astroid.FunctionDef): return if itemmethod.root().name != BUILTINS: return if not itemmethod.parent: return if itemmethod.parent.name not in SEQUENCE_TYPES: return # For ExtSlice objects coming from visit_extslice, no further # inference is necessary, since if we got this far the ExtSlice # is an error. if isinstance(node, astroid.ExtSlice): index_type = node else: index_type = safe_infer(node) if index_type is None or index_type is astroid.YES: return # Constants must be of type int if isinstance(index_type, astroid.Const): if isinstance(index_type.value, int): return # Instance values must be int, slice, or have an __index__ method elif isinstance(index_type, astroid.Instance): if index_type.pytype() in (BUILTINS + '.int', BUILTINS + '.slice'): return try: index_type.getattr('__index__') return except exceptions.NotFoundError: pass elif isinstance(index_type, astroid.Slice): # Delegate to visit_slice. A slice can be present # here after inferring the index node, which could # be a `slice(...)` call for instance. return self.visit_slice(index_type) # Anything else is an error self.add_message('invalid-sequence-index', node=node) @check_messages('invalid-slice-index') def visit_slice(self, node): # Check the type of each part of the slice for index in (node.lower, node.upper, node.step): if index is None: continue index_type = safe_infer(index) if index_type is None or index_type is astroid.YES: continue # Constants must of type int or None if isinstance(index_type, astroid.Const): if isinstance(index_type.value, (int, type(None))): continue # Instance values must be of type int, None or an object # with __index__ elif isinstance(index_type, astroid.Instance): if index_type.pytype() in (BUILTINS + '.int', BUILTINS + '.NoneType'): continue try: index_type.getattr('__index__') return except exceptions.NotFoundError: pass # Anything else is an error self.add_message('invalid-slice-index', node=node) @check_messages('not-context-manager') def visit_with(self, node): for ctx_mgr, _ in node.items: context = astroid.context.InferenceContext() infered = safe_infer(ctx_mgr, context=context) if infered is None or infered is astroid.YES: continue if isinstance(infered, bases.Generator): # Check if we are dealing with a function decorated # with contextlib.contextmanager. if decorated_with(infered.parent, ['contextlib.contextmanager']): continue # If the parent of the generator is not the context manager itself, # that means that it could have been returned from another # function which was the real context manager. # The following approach is more of a hack rather than a real # solution: walk all the inferred statements for the # given *ctx_mgr* and if you find one function scope # which is decorated, consider it to be the real # manager and give up, otherwise emit not-context-manager. # See the test file for not_context_manager for a couple # of self explaining tests. for path in six.moves.filter(None, _unflatten(context.path)): scope = path.scope() if not isinstance(scope, astroid.FunctionDef): continue if decorated_with(scope, ['contextlib.contextmanager']): break else: self.add_message('not-context-manager', node=node, args=(infered.name, )) else: try: infered.getattr('__enter__') infered.getattr('__exit__') except exceptions.NotFoundError: if isinstance(infered, astroid.Instance): # If we do not know the bases of this class, # just skip it. if not has_known_bases(infered): continue # Just ignore mixin classes. if self.config.ignore_mixin_members: if infered.name[-5:].lower() == 'mixin': continue self.add_message('not-context-manager', node=node, args=(infered.name, )) # Disabled until we'll have a more capable astroid. @check_messages('invalid-unary-operand-type') def _visit_unaryop(self, node): """Detect TypeErrors for unary operands.""" for error in node.type_errors(): # Let the error customize its output. self.add_message('invalid-unary-operand-type', args=str(error), node=node) @check_messages('unsupported-binary-operation') def _visit_binop(self, node): """Detect TypeErrors for binary arithmetic operands.""" self._check_binop_errors(node) @check_messages('unsupported-binary-operation') def _visit_augassign(self, node): """Detect TypeErrors for augmented binary arithmetic operands.""" self._check_binop_errors(node) def _check_binop_errors(self, node): for error in node.type_errors(): # Let the error customize its output. self.add_message('unsupported-binary-operation', args=str(error), node=node) def _check_membership_test(self, node): if is_inside_abstract_class(node): return if is_comprehension(node): return infered = safe_infer(node) if infered is None or infered is astroid.YES: return if not supports_membership_test(infered): self.add_message('unsupported-membership-test', args=node.as_string(), node=node) @check_messages('unsupported-membership-test') def visit_compare(self, node): if len(node.ops) != 1: return operator, right = node.ops[0] if operator in ['in', 'not in']: self._check_membership_test(right) @check_messages('unsubscriptable-object') def visit_subscript(self, node): if isinstance(node.value, (astroid.ListComp, astroid.DictComp)): return if isinstance(node.value, astroid.SetComp): self.add_message('unsubscriptable-object', args=node.value.as_string(), node=node.value) return infered = safe_infer(node.value) if infered is None or infered is astroid.YES: return if is_inside_abstract_class(node): return if not supports_subscript(infered): self.add_message('unsubscriptable-object', args=node.value.as_string(), node=node.value) class IterableChecker(BaseChecker): """ Checks for non-iterables used in an iterable context. Contexts include: - for-statement - starargs in function call - `yield from`-statement - list, dict and set comprehensions - generator expressions Also checks for non-mappings in function call kwargs. """ __implements__ = (IAstroidChecker,) name = 'iterable_check' msgs = {'E1133': ('Non-iterable value %s is used in an iterating context', 'not-an-iterable', 'Used when a non-iterable value is used in place where' 'iterable is expected'), 'E1134': ('Non-mapping value %s is used in a mapping context', 'not-a-mapping', 'Used when a non-mapping value is used in place where' 'mapping is expected'), } def _check_iterable(self, node): if is_inside_abstract_class(node): return if is_comprehension(node): return infered = safe_infer(node) if infered is None or infered is astroid.YES: return if not is_iterable(infered): self.add_message('not-an-iterable', args=node.as_string(), node=node) def _check_mapping(self, node): if is_inside_abstract_class(node): return if isinstance(node, astroid.DictComp): return infered = safe_infer(node) if infered is None or infered is astroid.YES: return if not is_mapping(infered): self.add_message('not-a-mapping', args=node.as_string(), node=node) @check_messages('not-an-iterable') def visit_for(self, node): self._check_iterable(node.iter) @check_messages('not-an-iterable') def visit_yieldfrom(self, node): self._check_iterable(node.value) @check_messages('not-an-iterable', 'not-a-mapping') def visit_call(self, node): for stararg in node.starargs: self._check_iterable(stararg.value) for kwarg in node.kwargs: self._check_mapping(kwarg.value) @check_messages('not-an-iterable') def visit_listcomp(self, node): for gen in node.generators: self._check_iterable(gen.iter) @check_messages('not-an-iterable') def visit_dictcomp(self, node): for gen in node.generators: self._check_iterable(gen.iter) @check_messages('not-an-iterable') def visit_setcomp(self, node): for gen in node.generators: self._check_iterable(gen.iter) @check_messages('not-an-iterable') def visit_generatorexp(self, node): for gen in node.generators: self._check_iterable(gen.iter) def register(linter): """required method to auto register this checker """ linter.register_checker(TypeChecker(linter)) linter.register_checker(IterableChecker(linter))