# Copyright (c) 2006-2016 LOGILAB S.A. (Paris, FRANCE) # Copyright (c) 2010 Daniel Harding # Copyright (c) 2012-2014 Google, Inc. # Copyright (c) 2013-2020 Claudiu Popa # Copyright (c) 2014 Brett Cannon # Copyright (c) 2014 Arun Persaud # Copyright (c) 2015 Nick Bastin # Copyright (c) 2015 Michael Kefeder # Copyright (c) 2015 Dmitry Pribysh # Copyright (c) 2015 Stephane Wirtel # Copyright (c) 2015 Cosmin Poieana # Copyright (c) 2015 Florian Bruhin # Copyright (c) 2015 Radu Ciorba # Copyright (c) 2015 Ionel Cristian Maries # Copyright (c) 2016, 2019 Ashley Whetter # Copyright (c) 2016, 2018 Jakub Wilk # Copyright (c) 2016-2017 Łukasz Rogalski # Copyright (c) 2016 Glenn Matthews # Copyright (c) 2016 Elias Dorneles # Copyright (c) 2016 Yannack # Copyright (c) 2016 Alex Jurkiewicz # Copyright (c) 2017, 2019-2021 Pierre Sassoulas # Copyright (c) 2017, 2019-2020 hippo91 # Copyright (c) 2017 danields # Copyright (c) 2017 Jacques Kvam # Copyright (c) 2017 ttenhoeve-aa # Copyright (c) 2018-2019 Nick Drozd # Copyright (c) 2018-2019 Ville Skyttä # Copyright (c) 2018 Sergei Lebedev <185856+superbobry@users.noreply.github.com> # Copyright (c) 2018 Lucas Cimon # Copyright (c) 2018 ssolanki # Copyright (c) 2018 Natalie Serebryakova # Copyright (c) 2018 Sushobhit <31987769+sushobhit27@users.noreply.github.com> # Copyright (c) 2018 SergeyKosarchuk # Copyright (c) 2018 Steven M. Vascellaro # Copyright (c) 2018 Mike Frysinger # Copyright (c) 2018 Chris Lamb # Copyright (c) 2018 glmdgrielson <32415403+glmdgrielson@users.noreply.github.com> # Copyright (c) 2019 Daniel Draper # Copyright (c) 2019 Hugo van Kemenade # Copyright (c) 2019 Niko Wenselowski # Copyright (c) 2019 Nikita Sobolev # Copyright (c) 2019 Oisín Moran # Copyright (c) 2019 Fantix King # Copyright (c) 2020 Peter Kolbus # Copyright (c) 2020 ethan-leba # Copyright (c) 2020 へーさん # Copyright (c) 2020 Damien Baty # Copyright (c) 2020 Ram Rachum # Copyright (c) 2020 Anthony Sottile # Copyright (c) 2020 bernie gray # Copyright (c) 2020 Gabriel R Sezefredo # Copyright (c) 2020 Benny # Copyright (c) 2020 Anubhav <35621759+anubh-v@users.noreply.github.com> # Copyright (c) 2021 Marc Mueller <30130371+cdce8p@users.noreply.github.com> # Copyright (c) 2021 Or Bahari # Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html # For details: https://github.com/PyCQA/pylint/blob/master/COPYING """basic checker for Python code""" import builtins import collections import itertools import re import sys from typing import Pattern import astroid from pylint import checkers, exceptions, interfaces from pylint import utils as lint_utils from pylint.checkers import utils from pylint.checkers.utils import ( is_overload_stub, is_property_deleter, is_property_setter, ) from pylint.reporters.ureports import nodes as reporter_nodes class NamingStyle: """It may seem counterintuitive that single naming style has multiple "accepted" forms of regular expressions, but we need to special-case stuff like dunder names in method names.""" ANY: Pattern[str] = re.compile(".*") CLASS_NAME_RGX: Pattern[str] = ANY MOD_NAME_RGX: Pattern[str] = ANY CONST_NAME_RGX: Pattern[str] = ANY COMP_VAR_RGX: Pattern[str] = ANY DEFAULT_NAME_RGX: Pattern[str] = ANY CLASS_ATTRIBUTE_RGX: Pattern[str] = ANY @classmethod def get_regex(cls, name_type): return { "module": cls.MOD_NAME_RGX, "const": cls.CONST_NAME_RGX, "class": cls.CLASS_NAME_RGX, "function": cls.DEFAULT_NAME_RGX, "method": cls.DEFAULT_NAME_RGX, "attr": cls.DEFAULT_NAME_RGX, "argument": cls.DEFAULT_NAME_RGX, "variable": cls.DEFAULT_NAME_RGX, "class_attribute": cls.CLASS_ATTRIBUTE_RGX, "class_const": cls.CONST_NAME_RGX, "inlinevar": cls.COMP_VAR_RGX, }[name_type] class SnakeCaseStyle(NamingStyle): """Regex rules for snake_case naming style.""" CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]+$") MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$") CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]*|__.*__)$") COMP_VAR_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$") DEFAULT_NAME_RGX = re.compile( r"([^\W\dA-Z][^\WA-Z]{2,}|_[^\WA-Z]*|__[^\WA-Z\d_][^\WA-Z]+__)$" ) CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]{2,}|__.*__)$") class CamelCaseStyle(NamingStyle): """Regex rules for camelCase naming style.""" CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]+$") MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$") CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]*|__.*__)$") COMP_VAR_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$") DEFAULT_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$") CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__.*__)$") class PascalCaseStyle(NamingStyle): """Regex rules for PascalCase naming style.""" CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]+$") MOD_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]+$") CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]*|__.*__)$") COMP_VAR_RGX = re.compile(r"[^\W\da-z][^\W_]+$") DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$") CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\W_]{2,}$") class UpperCaseStyle(NamingStyle): """Regex rules for UPPER_CASE naming style.""" CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$") MOD_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$") CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]*|__.*__)$") COMP_VAR_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$") DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]{2,}|__[^\W\dA-Z_]\w+__)$") CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\Wa-z]{2,}$") class AnyStyle(NamingStyle): pass NAMING_STYLES = { "snake_case": SnakeCaseStyle, "camelCase": CamelCaseStyle, "PascalCase": PascalCaseStyle, "UPPER_CASE": UpperCaseStyle, "any": AnyStyle, } # do not require a doc string on private/system methods NO_REQUIRED_DOC_RGX = re.compile("^_") REVERSED_PROTOCOL_METHOD = "__reversed__" SEQUENCE_PROTOCOL_METHODS = ("__getitem__", "__len__") REVERSED_METHODS = (SEQUENCE_PROTOCOL_METHODS, (REVERSED_PROTOCOL_METHOD,)) TYPECHECK_COMPARISON_OPERATORS = frozenset(("is", "is not", "==", "!=")) LITERAL_NODE_TYPES = (astroid.Const, astroid.Dict, astroid.List, astroid.Set) UNITTEST_CASE = "unittest.case" BUILTINS = builtins.__name__ TYPE_QNAME = "%s.type" % BUILTINS ABC_METACLASSES = {"_py_abc.ABCMeta", "abc.ABCMeta"} # Python 3.7+, # Name categories that are always consistent with all naming conventions. EXEMPT_NAME_CATEGORIES = {"exempt", "ignore"} # A mapping from qname -> symbol, to be used when generating messages # about dangerous default values as arguments DEFAULT_ARGUMENT_SYMBOLS = dict( zip( [".".join([BUILTINS, x]) for x in ("set", "dict", "list")], ["set()", "{}", "[]"], ), **{ x: "%s()" % x for x in ( "collections.deque", "collections.ChainMap", "collections.Counter", "collections.OrderedDict", "collections.defaultdict", "collections.UserDict", "collections.UserList", ) }, ) REVERSED_COMPS = {"<": ">", "<=": ">=", ">": "<", ">=": "<="} COMPARISON_OPERATORS = frozenset(("==", "!=", "<", ">", "<=", ">=")) # List of methods which can be redefined REDEFINABLE_METHODS = frozenset(("__module__",)) TYPING_FORWARD_REF_QNAME = "typing.ForwardRef" def _redefines_import(node): """Detect that the given node (AssignName) is inside an exception handler and redefines an import from the tryexcept body. Returns True if the node redefines an import, False otherwise. """ current = node while current and not isinstance(current.parent, astroid.ExceptHandler): current = current.parent if not current or not utils.error_of_type(current.parent, ImportError): return False try_block = current.parent.parent for import_node in try_block.nodes_of_class((astroid.ImportFrom, astroid.Import)): for name, alias in import_node.names: if alias: if alias == node.name: return True elif name == node.name: return True return False def in_loop(node): """return True if the node is inside a kind of for loop""" parent = node.parent while parent is not None: if isinstance( parent, ( astroid.For, astroid.ListComp, astroid.SetComp, astroid.DictComp, astroid.GeneratorExp, ), ): return True parent = parent.parent return False def in_nested_list(nested_list, obj): """return true if the object is an element of or of a nested list """ for elmt in nested_list: if isinstance(elmt, (list, tuple)): if in_nested_list(elmt, obj): return True elif elmt == obj: return True return False def _get_break_loop_node(break_node): """ Returns the loop node that holds the break node in arguments. Args: break_node (astroid.Break): the break node of interest. Returns: astroid.For or astroid.While: the loop node holding the break node. """ loop_nodes = (astroid.For, astroid.While) parent = break_node.parent while not isinstance(parent, loop_nodes) or break_node in getattr( parent, "orelse", [] ): break_node = parent parent = parent.parent if parent is None: break return parent def _loop_exits_early(loop): """ Returns true if a loop may ends up in a break statement. Args: loop (astroid.For, astroid.While): the loop node inspected. Returns: bool: True if the loop may ends up in a break statement, False otherwise. """ loop_nodes = (astroid.For, astroid.While) definition_nodes = (astroid.FunctionDef, astroid.ClassDef) inner_loop_nodes = [ _node for _node in loop.nodes_of_class(loop_nodes, skip_klass=definition_nodes) if _node != loop ] return any( _node for _node in loop.nodes_of_class(astroid.Break, skip_klass=definition_nodes) if _get_break_loop_node(_node) not in inner_loop_nodes ) def _is_multi_naming_match(match, node_type, confidence): return ( match is not None and match.lastgroup is not None and match.lastgroup not in EXEMPT_NAME_CATEGORIES and (node_type != "method" or confidence != interfaces.INFERENCE_FAILURE) ) BUILTIN_PROPERTY = "builtins.property" def _get_properties(config): """Returns a tuple of property classes and names. Property classes are fully qualified, such as 'abc.abstractproperty' and property names are the actual names, such as 'abstract_property'. """ property_classes = {BUILTIN_PROPERTY} property_names = set() # Not returning 'property', it has its own check. if config is not None: property_classes.update(config.property_classes) property_names.update( prop.rsplit(".", 1)[-1] for prop in config.property_classes ) return property_classes, property_names def _determine_function_name_type(node: astroid.FunctionDef, config=None): """Determine the name type whose regex the a function's name should match. :param node: A function node. :param config: Configuration from which to pull additional property classes. :type config: :class:`optparse.Values` :returns: One of ('function', 'method', 'attr') :rtype: str """ property_classes, property_names = _get_properties(config) if not node.is_method(): return "function" if is_property_setter(node) or is_property_deleter(node): # If the function is decorated using the prop_method.{setter,getter} # form, treat it like an attribute as well. return "attr" if node.decorators: decorators = node.decorators.nodes else: decorators = [] for decorator in decorators: # If the function is a property (decorated with @property # or @abc.abstractproperty), the name type is 'attr'. if isinstance(decorator, astroid.Name) or ( isinstance(decorator, astroid.Attribute) and decorator.attrname in property_names ): inferred = utils.safe_infer(decorator) if ( inferred and hasattr(inferred, "qname") and inferred.qname() in property_classes ): return "attr" return "method" def _has_abstract_methods(node): """ Determine if the given `node` has abstract methods. The methods should be made abstract by decorating them with `abc` decorators. """ return len(utils.unimplemented_abstract_methods(node)) > 0 def report_by_type_stats(sect, stats, old_stats): """make a report of * percentage of different types documented * percentage of different types with a bad name """ # percentage of different types documented and/or with a bad name nice_stats = {} for node_type in ("module", "class", "method", "function"): try: total = stats[node_type] except KeyError as e: raise exceptions.EmptyReportError() from e nice_stats[node_type] = {} if total != 0: try: documented = total - stats["undocumented_" + node_type] percent = (documented * 100.0) / total nice_stats[node_type]["percent_documented"] = "%.2f" % percent except KeyError: nice_stats[node_type]["percent_documented"] = "NC" try: percent = (stats["badname_" + node_type] * 100.0) / total nice_stats[node_type]["percent_badname"] = "%.2f" % percent except KeyError: nice_stats[node_type]["percent_badname"] = "NC" lines = ("type", "number", "old number", "difference", "%documented", "%badname") for node_type in ("module", "class", "method", "function"): new = stats[node_type] old = old_stats.get(node_type, None) if old is not None: diff_str = lint_utils.diff_string(old, new) else: old, diff_str = "NC", "NC" lines += ( node_type, str(new), str(old), diff_str, nice_stats[node_type].get("percent_documented", "0"), nice_stats[node_type].get("percent_badname", "0"), ) sect.append(reporter_nodes.Table(children=lines, cols=6, rheaders=1)) def redefined_by_decorator(node): """return True if the object is a method redefined via decorator. For example: @property def x(self): return self._x @x.setter def x(self, value): self._x = value """ if node.decorators: for decorator in node.decorators.nodes: if ( isinstance(decorator, astroid.Attribute) and getattr(decorator.expr, "name", None) == node.name ): return True return False class _BasicChecker(checkers.BaseChecker): __implements__ = interfaces.IAstroidChecker name = "basic" class BasicErrorChecker(_BasicChecker): msgs = { "E0100": ( "__init__ method is a generator", "init-is-generator", "Used when the special class method __init__ is turned into a " "generator by a yield in its body.", ), "E0101": ( "Explicit return in __init__", "return-in-init", "Used when the special class method __init__ has an explicit " "return value.", ), "E0102": ( "%s already defined line %s", "function-redefined", "Used when a function / class / method is redefined.", ), "E0103": ( "%r not properly in loop", "not-in-loop", "Used when break or continue keywords are used outside a loop.", ), "E0104": ( "Return outside function", "return-outside-function", 'Used when a "return" statement is found outside a function or method.', ), "E0105": ( "Yield outside function", "yield-outside-function", 'Used when a "yield" statement is found outside a function or method.', ), "E0106": ( "Return with argument inside generator", "return-arg-in-generator", 'Used when a "return" statement with an argument is found ' "outside in a generator function or method (e.g. with some " '"yield" statements).', {"maxversion": (3, 3)}, ), "E0107": ( "Use of the non-existent %s operator", "nonexistent-operator", "Used when you attempt to use the C-style pre-increment or " "pre-decrement operator -- and ++, which doesn't exist in Python.", ), "E0108": ( "Duplicate argument name %s in function definition", "duplicate-argument-name", "Duplicate argument names in function definitions are syntax errors.", ), "E0110": ( "Abstract class %r with abstract methods instantiated", "abstract-class-instantiated", "Used when an abstract class with `abc.ABCMeta` as metaclass " "has abstract methods and is instantiated.", ), "W0120": ( "Else clause on loop without a break statement", "useless-else-on-loop", "Loops should only have an else clause if they can exit early " "with a break statement, otherwise the statements under else " "should be on the same scope as the loop itself.", ), "E0112": ( "More than one starred expression in assignment", "too-many-star-expressions", "Emitted when there are more than one starred " "expressions (`*x`) in an assignment. This is a SyntaxError.", ), "E0113": ( "Starred assignment target must be in a list or tuple", "invalid-star-assignment-target", "Emitted when a star expression is used as a starred assignment target.", ), "E0114": ( "Can use starred expression only in assignment target", "star-needs-assignment-target", "Emitted when a star expression is not used in an assignment target.", ), "E0115": ( "Name %r is nonlocal and global", "nonlocal-and-global", "Emitted when a name is both nonlocal and global.", ), "E0116": ( "'continue' not supported inside 'finally' clause", "continue-in-finally", "Emitted when the `continue` keyword is found " "inside a finally clause, which is a SyntaxError.", {"maxversion": (3, 8)}, ), "E0117": ( "nonlocal name %s found without binding", "nonlocal-without-binding", "Emitted when a nonlocal variable does not have an attached " "name somewhere in the parent scopes", ), "E0118": ( "Name %r is used prior to global declaration", "used-prior-global-declaration", "Emitted when a name is used prior a global declaration, " "which results in an error since Python 3.6.", {"minversion": (3, 6)}, ), } @utils.check_messages("function-redefined") def visit_classdef(self, node): self._check_redefinition("class", node) def _too_many_starred_for_tuple(self, assign_tuple): starred_count = 0 for elem in assign_tuple.itered(): if isinstance(elem, astroid.Tuple): return self._too_many_starred_for_tuple(elem) if isinstance(elem, astroid.Starred): starred_count += 1 return starred_count > 1 @utils.check_messages("too-many-star-expressions", "invalid-star-assignment-target") def visit_assign(self, node): # Check *a, *b = ... assign_target = node.targets[0] # Check *a = b if isinstance(node.targets[0], astroid.Starred): self.add_message("invalid-star-assignment-target", node=node) if not isinstance(assign_target, astroid.Tuple): return if self._too_many_starred_for_tuple(assign_target): self.add_message("too-many-star-expressions", node=node) @utils.check_messages("star-needs-assignment-target") def visit_starred(self, node): """Check that a Starred expression is used in an assignment target.""" if isinstance(node.parent, astroid.Call): # f(*args) is converted to Call(args=[Starred]), so ignore # them for this check. return if isinstance( node.parent, (astroid.List, astroid.Tuple, astroid.Set, astroid.Dict) ): # PEP 448 unpacking. return stmt = node.statement() if not isinstance(stmt, astroid.Assign): return if stmt.value is node or stmt.value.parent_of(node): self.add_message("star-needs-assignment-target", node=node) @utils.check_messages( "init-is-generator", "return-in-init", "function-redefined", "return-arg-in-generator", "duplicate-argument-name", "nonlocal-and-global", "used-prior-global-declaration", ) def visit_functiondef(self, node): self._check_nonlocal_and_global(node) self._check_name_used_prior_global(node) if not redefined_by_decorator( node ) and not utils.is_registered_in_singledispatch_function(node): self._check_redefinition(node.is_method() and "method" or "function", node) # checks for max returns, branch, return in __init__ returns = node.nodes_of_class( astroid.Return, skip_klass=(astroid.FunctionDef, astroid.ClassDef) ) if node.is_method() and node.name == "__init__": if node.is_generator(): self.add_message("init-is-generator", node=node) else: values = [r.value for r in returns] # Are we returning anything but None from constructors if any(v for v in values if not utils.is_none(v)): self.add_message("return-in-init", node=node) # Check for duplicate names by clustering args with same name for detailed report arg_clusters = collections.defaultdict(list) arguments = filter(None, [node.args.args, node.args.kwonlyargs]) for arg in itertools.chain.from_iterable(arguments): arg_clusters[arg.name].append(arg) # provide detailed report about each repeated argument for argument_duplicates in arg_clusters.values(): if len(argument_duplicates) != 1: for argument in argument_duplicates: self.add_message( "duplicate-argument-name", line=argument.lineno, node=argument, args=(argument.name,), ) visit_asyncfunctiondef = visit_functiondef def _check_name_used_prior_global(self, node): scope_globals = { name: child for child in node.nodes_of_class(astroid.Global) for name in child.names if child.scope() is node } if not scope_globals: return for node_name in node.nodes_of_class(astroid.Name): if node_name.scope() is not node: continue name = node_name.name corresponding_global = scope_globals.get(name) if not corresponding_global: continue global_lineno = corresponding_global.fromlineno if global_lineno and global_lineno > node_name.fromlineno: self.add_message( "used-prior-global-declaration", node=node_name, args=(name,) ) def _check_nonlocal_and_global(self, node): """Check that a name is both nonlocal and global.""" def same_scope(current): return current.scope() is node from_iter = itertools.chain.from_iterable nonlocals = set( from_iter( child.names for child in node.nodes_of_class(astroid.Nonlocal) if same_scope(child) ) ) if not nonlocals: return global_vars = set( from_iter( child.names for child in node.nodes_of_class(astroid.Global) if same_scope(child) ) ) for name in nonlocals.intersection(global_vars): self.add_message("nonlocal-and-global", args=(name,), node=node) @utils.check_messages("return-outside-function") def visit_return(self, node): if not isinstance(node.frame(), astroid.FunctionDef): self.add_message("return-outside-function", node=node) @utils.check_messages("yield-outside-function") def visit_yield(self, node): self._check_yield_outside_func(node) @utils.check_messages("yield-outside-function") def visit_yieldfrom(self, node): self._check_yield_outside_func(node) @utils.check_messages("not-in-loop", "continue-in-finally") def visit_continue(self, node): self._check_in_loop(node, "continue") @utils.check_messages("not-in-loop") def visit_break(self, node): self._check_in_loop(node, "break") @utils.check_messages("useless-else-on-loop") def visit_for(self, node): self._check_else_on_loop(node) @utils.check_messages("useless-else-on-loop") def visit_while(self, node): self._check_else_on_loop(node) @utils.check_messages("nonexistent-operator") def visit_unaryop(self, node): """check use of the non-existent ++ and -- operator operator""" if ( (node.op in "+-") and isinstance(node.operand, astroid.UnaryOp) and (node.operand.op == node.op) ): self.add_message("nonexistent-operator", node=node, args=node.op * 2) def _check_nonlocal_without_binding(self, node, name): current_scope = node.scope() while True: if current_scope.parent is None: break if not isinstance(current_scope, (astroid.ClassDef, astroid.FunctionDef)): self.add_message("nonlocal-without-binding", args=(name,), node=node) return if name not in current_scope.locals: current_scope = current_scope.parent.scope() continue # Okay, found it. return if not isinstance(current_scope, astroid.FunctionDef): self.add_message("nonlocal-without-binding", args=(name,), node=node) @utils.check_messages("nonlocal-without-binding") def visit_nonlocal(self, node): for name in node.names: self._check_nonlocal_without_binding(node, name) @utils.check_messages("abstract-class-instantiated") def visit_call(self, node): """Check instantiating abstract class with abc.ABCMeta as metaclass. """ try: for inferred in node.func.infer(): self._check_inferred_class_is_abstract(inferred, node) except astroid.InferenceError: return def _check_inferred_class_is_abstract(self, inferred, node): if not isinstance(inferred, astroid.ClassDef): return klass = utils.node_frame_class(node) if klass is inferred: # Don't emit the warning if the class is instantiated # in its own body or if the call is not an instance # creation. If the class is instantiated into its own # body, we're expecting that it knows what it is doing. return # __init__ was called abstract_methods = _has_abstract_methods(inferred) if not abstract_methods: return metaclass = inferred.metaclass() if metaclass is None: # Python 3.4 has `abc.ABC`, which won't be detected # by ClassNode.metaclass() for ancestor in inferred.ancestors(): if ancestor.qname() == "abc.ABC": self.add_message( "abstract-class-instantiated", args=(inferred.name,), node=node ) break return if metaclass.qname() in ABC_METACLASSES: self.add_message( "abstract-class-instantiated", args=(inferred.name,), node=node ) def _check_yield_outside_func(self, node): if not isinstance(node.frame(), (astroid.FunctionDef, astroid.Lambda)): self.add_message("yield-outside-function", node=node) def _check_else_on_loop(self, node): """Check that any loop with an else clause has a break statement.""" if node.orelse and not _loop_exits_early(node): self.add_message( "useless-else-on-loop", node=node, # This is not optimal, but the line previous # to the first statement in the else clause # will usually be the one that contains the else:. line=node.orelse[0].lineno - 1, ) def _check_in_loop(self, node, node_name): """check that a node is inside a for or while loop""" _node = node.parent while _node: if isinstance(_node, (astroid.For, astroid.While)): if node not in _node.orelse: return if isinstance(_node, (astroid.ClassDef, astroid.FunctionDef)): break if ( isinstance(_node, astroid.TryFinally) and node in _node.finalbody and isinstance(node, astroid.Continue) ): self.add_message("continue-in-finally", node=node) _node = _node.parent self.add_message("not-in-loop", node=node, args=node_name) def _check_redefinition(self, redeftype, node): """check for redefinition of a function / method / class name""" parent_frame = node.parent.frame() # Ignore function stubs created for type information redefinitions = parent_frame.locals[node.name] defined_self = next( (local for local in redefinitions if not utils.is_overload_stub(local)), node, ) if defined_self is not node and not astroid.are_exclusive(node, defined_self): # Additional checks for methods which are not considered # redefined, since they are already part of the base API. if ( isinstance(parent_frame, astroid.ClassDef) and node.name in REDEFINABLE_METHODS ): return # Skip typing.overload() functions. if utils.is_overload_stub(node): return # Exempt functions redefined on a condition. if isinstance(node.parent, astroid.If): # Exempt "if not " cases if ( isinstance(node.parent.test, astroid.UnaryOp) and node.parent.test.op == "not" and isinstance(node.parent.test.operand, astroid.Name) and node.parent.test.operand.name == node.name ): return # Exempt "if is not None" cases # pylint: disable=too-many-boolean-expressions if ( isinstance(node.parent.test, astroid.Compare) and isinstance(node.parent.test.left, astroid.Name) and node.parent.test.left.name == node.name and node.parent.test.ops[0][0] == "is" and isinstance(node.parent.test.ops[0][1], astroid.Const) and node.parent.test.ops[0][1].value is None ): return # Check if we have forward references for this node. try: redefinition_index = redefinitions.index(node) except ValueError: pass else: for redefinition in redefinitions[:redefinition_index]: inferred = utils.safe_infer(redefinition) if ( inferred and isinstance(inferred, astroid.Instance) and inferred.qname() == TYPING_FORWARD_REF_QNAME ): return dummy_variables_rgx = lint_utils.get_global_option( self, "dummy-variables-rgx", default=None ) if dummy_variables_rgx and dummy_variables_rgx.match(node.name): return self.add_message( "function-redefined", node=node, args=(redeftype, defined_self.fromlineno), ) class BasicChecker(_BasicChecker): """checks for : * doc strings * number of arguments, local variables, branches, returns and statements in functions, methods * required module attributes * dangerous default values as arguments * redefinition of function / method / class * uses of the global statement """ __implements__ = interfaces.IAstroidChecker name = "basic" msgs = { "W0101": ( "Unreachable code", "unreachable", 'Used when there is some code behind a "return" or "raise" ' "statement, which will never be accessed.", ), "W0102": ( "Dangerous default value %s as argument", "dangerous-default-value", "Used when a mutable value as list or dictionary is detected in " "a default value for an argument.", ), "W0104": ( "Statement seems to have no effect", "pointless-statement", "Used when a statement doesn't have (or at least seems to) any effect.", ), "W0105": ( "String statement has no effect", "pointless-string-statement", "Used when a string is used as a statement (which of course " "has no effect). This is a particular case of W0104 with its " "own message so you can easily disable it if you're using " "those strings as documentation, instead of comments.", ), "W0106": ( 'Expression "%s" is assigned to nothing', "expression-not-assigned", "Used when an expression that is not a function call is assigned " "to nothing. Probably something else was intended.", ), "W0108": ( "Lambda may not be necessary", "unnecessary-lambda", "Used when the body of a lambda expression is a function call " "on the same argument list as the lambda itself; such lambda " "expressions are in all but a few cases replaceable with the " "function being called in the body of the lambda.", ), "W0109": ( "Duplicate key %r in dictionary", "duplicate-key", "Used when a dictionary expression binds the same key multiple times.", ), "W0122": ( "Use of exec", "exec-used", 'Used when you use the "exec" statement (function for Python ' "3), to discourage its usage. That doesn't " "mean you cannot use it !", ), "W0123": ( "Use of eval", "eval-used", 'Used when you use the "eval" function, to discourage its ' "usage. Consider using `ast.literal_eval` for safely evaluating " "strings containing Python expressions " "from untrusted sources. ", ), "W0150": ( "%s statement in finally block may swallow exception", "lost-exception", "Used when a break or a return statement is found inside the " "finally clause of a try...finally block: the exceptions raised " "in the try clause will be silently swallowed instead of being " "re-raised.", ), "W0199": ( "Assert called on a 2-item-tuple. Did you mean 'assert x,y'?", "assert-on-tuple", "A call of assert on a tuple will always evaluate to true if " "the tuple is not empty, and will always evaluate to false if " "it is.", ), "W0124": ( 'Following "as" with another context manager looks like a tuple.', "confusing-with-statement", "Emitted when a `with` statement component returns multiple values " "and uses name binding with `as` only for a part of those values, " "as in with ctx() as a, b. This can be misleading, since it's not " "clear if the context manager returns a tuple or if the node without " "a name binding is another context manager.", ), "W0125": ( "Using a conditional statement with a constant value", "using-constant-test", "Emitted when a conditional statement (If or ternary if) " "uses a constant value for its test. This might not be what " "the user intended to do.", ), "W0126": ( "Using a conditional statement with potentially wrong function or method call due to missing parentheses", "missing-parentheses-for-call-in-test", "Emitted when a conditional statement (If or ternary if) " "seems to wrongly call a function due to missing parentheses", ), "W0127": ( "Assigning the same variable %r to itself", "self-assigning-variable", "Emitted when we detect that a variable is assigned to itself", ), "W0128": ( "Redeclared variable %r in assignment", "redeclared-assigned-name", "Emitted when we detect that a variable was redeclared in the same assignment.", ), "E0111": ( "The first reversed() argument is not a sequence", "bad-reversed-sequence", "Used when the first argument to reversed() builtin " "isn't a sequence (does not implement __reversed__, " "nor __getitem__ and __len__", ), "E0119": ( "format function is not called on str", "misplaced-format-function", "Emitted when format function is not called on str object. " 'e.g doing print("value: {}").format(123) instead of ' 'print("value: {}".format(123)). This might not be what the user ' "intended to do.", ), "W0129": ( "Assert statement has a string literal as its first argument. The assert will %s fail.", "assert-on-string-literal", "Used when an assert statement has a string literal as its first argument, which will " "cause the assert to always pass.", ), } reports = (("RP0101", "Statistics by type", report_by_type_stats),) def __init__(self, linter): _BasicChecker.__init__(self, linter) self.stats = None self._tryfinallys = None def open(self): """initialize visit variables and statistics""" self._tryfinallys = [] self.stats = self.linter.add_stats(module=0, function=0, method=0, class_=0) @utils.check_messages("using-constant-test", "missing-parentheses-for-call-in-test") def visit_if(self, node): self._check_using_constant_test(node, node.test) @utils.check_messages("using-constant-test", "missing-parentheses-for-call-in-test") def visit_ifexp(self, node): self._check_using_constant_test(node, node.test) @utils.check_messages("using-constant-test", "missing-parentheses-for-call-in-test") def visit_comprehension(self, node): if node.ifs: for if_test in node.ifs: self._check_using_constant_test(node, if_test) def _check_using_constant_test(self, node, test): const_nodes = ( astroid.Module, astroid.scoped_nodes.GeneratorExp, astroid.Lambda, astroid.FunctionDef, astroid.ClassDef, astroid.bases.Generator, astroid.UnboundMethod, astroid.BoundMethod, astroid.Module, ) structs = (astroid.Dict, astroid.Tuple, astroid.Set) # These nodes are excepted, since they are not constant # values, requiring a computation to happen. except_nodes = ( astroid.Call, astroid.BinOp, astroid.BoolOp, astroid.UnaryOp, astroid.Subscript, ) inferred = None emit = isinstance(test, (astroid.Const,) + structs + const_nodes) if not isinstance(test, except_nodes): inferred = utils.safe_infer(test) if emit: self.add_message("using-constant-test", node=node) elif isinstance(inferred, const_nodes): # If the constant node is a FunctionDef or Lambda then # it may be a illicit function call due to missing parentheses call_inferred = None try: if isinstance(inferred, astroid.FunctionDef): call_inferred = inferred.infer_call_result() elif isinstance(inferred, astroid.Lambda): call_inferred = inferred.infer_call_result(node) except astroid.InferenceError: call_inferred = None if call_inferred: try: for inf_call in call_inferred: if inf_call != astroid.Uninferable: self.add_message( "missing-parentheses-for-call-in-test", node=node ) break except astroid.InferenceError: pass self.add_message("using-constant-test", node=node) def visit_module(self, _): """check module name, docstring and required arguments""" self.stats["module"] += 1 def visit_classdef(self, node): # pylint: disable=unused-argument """check module name, docstring and redefinition increment branch counter """ self.stats["class"] += 1 @utils.check_messages( "pointless-statement", "pointless-string-statement", "expression-not-assigned" ) def visit_expr(self, node): """Check for various kind of statements without effect""" expr = node.value if isinstance(expr, astroid.Const) and isinstance(expr.value, str): # treat string statement in a separated message # Handle PEP-257 attribute docstrings. # An attribute docstring is defined as being a string right after # an assignment at the module level, class level or __init__ level. scope = expr.scope() if isinstance( scope, (astroid.ClassDef, astroid.Module, astroid.FunctionDef) ): if isinstance(scope, astroid.FunctionDef) and scope.name != "__init__": pass else: sibling = expr.previous_sibling() if ( sibling is not None and sibling.scope() is scope and isinstance(sibling, (astroid.Assign, astroid.AnnAssign)) ): return self.add_message("pointless-string-statement", node=node) return # Ignore if this is : # * a direct function call # * the unique child of a try/except body # * a yield statement # * an ellipsis (which can be used on Python 3 instead of pass) # warn W0106 if we have any underlying function call (we can't predict # side effects), else pointless-statement if ( isinstance( expr, (astroid.Yield, astroid.Await, astroid.Ellipsis, astroid.Call) ) or ( isinstance(node.parent, astroid.TryExcept) and node.parent.body == [node] ) or (isinstance(expr, astroid.Const) and expr.value is Ellipsis) ): return if any(expr.nodes_of_class(astroid.Call)): self.add_message( "expression-not-assigned", node=node, args=expr.as_string() ) else: self.add_message("pointless-statement", node=node) @staticmethod def _filter_vararg(node, call_args): # Return the arguments for the given call which are # not passed as vararg. for arg in call_args: if isinstance(arg, astroid.Starred): if ( isinstance(arg.value, astroid.Name) and arg.value.name != node.args.vararg ): yield arg else: yield arg @staticmethod def _has_variadic_argument(args, variadic_name): if not args: return True for arg in args: if isinstance(arg.value, astroid.Name): if arg.value.name != variadic_name: return True else: return True return False @utils.check_messages("unnecessary-lambda") def visit_lambda(self, node): """check whether or not the lambda is suspicious""" # if the body of the lambda is a call expression with the same # argument list as the lambda itself, then the lambda is # possibly unnecessary and at least suspicious. if node.args.defaults: # If the arguments of the lambda include defaults, then a # judgment cannot be made because there is no way to check # that the defaults defined by the lambda are the same as # the defaults defined by the function called in the body # of the lambda. return call = node.body if not isinstance(call, astroid.Call): # The body of the lambda must be a function call expression # for the lambda to be unnecessary. return if isinstance(node.body.func, astroid.Attribute) and isinstance( node.body.func.expr, astroid.Call ): # Chained call, the intermediate call might # return something else (but we don't check that, yet). return call_site = astroid.arguments.CallSite.from_call(call) ordinary_args = list(node.args.args) new_call_args = list(self._filter_vararg(node, call.args)) if node.args.kwarg: if self._has_variadic_argument(call.kwargs, node.args.kwarg): return if node.args.vararg: if self._has_variadic_argument(call.starargs, node.args.vararg): return elif call.starargs: return if call.keywords: # Look for additional keyword arguments that are not part # of the lambda's signature lambda_kwargs = {keyword.name for keyword in node.args.defaults} if len(lambda_kwargs) != len(call_site.keyword_arguments): # Different lengths, so probably not identical return if set(call_site.keyword_arguments).difference(lambda_kwargs): return # The "ordinary" arguments must be in a correspondence such that: # ordinary_args[i].name == call.args[i].name. if len(ordinary_args) != len(new_call_args): return for arg, passed_arg in zip(ordinary_args, new_call_args): if not isinstance(passed_arg, astroid.Name): return if arg.name != passed_arg.name: return self.add_message("unnecessary-lambda", line=node.fromlineno, node=node) @utils.check_messages("dangerous-default-value") def visit_functiondef(self, node): """check function name, docstring, arguments, redefinition, variable names, max locals """ self.stats["method" if node.is_method() else "function"] += 1 self._check_dangerous_default(node) visit_asyncfunctiondef = visit_functiondef def _check_dangerous_default(self, node): """Check for dangerous default values as arguments.""" def is_iterable(internal_node): return isinstance(internal_node, (astroid.List, astroid.Set, astroid.Dict)) defaults = node.args.defaults or [] + node.args.kw_defaults or [] for default in defaults: if not default: continue try: value = next(default.infer()) except astroid.InferenceError: continue if ( isinstance(value, astroid.Instance) and value.qname() in DEFAULT_ARGUMENT_SYMBOLS ): if value is default: msg = DEFAULT_ARGUMENT_SYMBOLS[value.qname()] elif isinstance(value, astroid.Instance) or is_iterable(value): # We are here in the following situation(s): # * a dict/set/list/tuple call which wasn't inferred # to a syntax node ({}, () etc.). This can happen # when the arguments are invalid or unknown to # the inference. # * a variable from somewhere else, which turns out to be a list # or a dict. if is_iterable(default): msg = value.pytype() elif isinstance(default, astroid.Call): msg = f"{value.name}() ({value.qname()})" else: msg = f"{default.as_string()} ({value.qname()})" else: # this argument is a name msg = f"{default.as_string()} ({DEFAULT_ARGUMENT_SYMBOLS[value.qname()]})" self.add_message("dangerous-default-value", node=node, args=(msg,)) @utils.check_messages("unreachable", "lost-exception") def visit_return(self, node): """1 - check is the node has a right sibling (if so, that's some unreachable code) 2 - check is the node is inside the finally clause of a try...finally block """ self._check_unreachable(node) # Is it inside final body of a try...finally bloc ? self._check_not_in_finally(node, "return", (astroid.FunctionDef,)) @utils.check_messages("unreachable") def visit_continue(self, node): """check is the node has a right sibling (if so, that's some unreachable code) """ self._check_unreachable(node) @utils.check_messages("unreachable", "lost-exception") def visit_break(self, node): """1 - check is the node has a right sibling (if so, that's some unreachable code) 2 - check is the node is inside the finally clause of a try...finally block """ # 1 - Is it right sibling ? self._check_unreachable(node) # 2 - Is it inside final body of a try...finally bloc ? self._check_not_in_finally(node, "break", (astroid.For, astroid.While)) @utils.check_messages("unreachable") def visit_raise(self, node): """check if the node has a right sibling (if so, that's some unreachable code) """ self._check_unreachable(node) @utils.check_messages("exec-used") def visit_exec(self, node): """just print a warning on exec statements""" self.add_message("exec-used", node=node) def _check_misplaced_format_function(self, call_node): if not isinstance(call_node.func, astroid.Attribute): return if call_node.func.attrname != "format": return expr = utils.safe_infer(call_node.func.expr) if expr is astroid.Uninferable: return if not expr: # we are doubtful on inferred type of node, so here just check if format # was called on print() call_expr = call_node.func.expr if not isinstance(call_expr, astroid.Call): return if ( isinstance(call_expr.func, astroid.Name) and call_expr.func.name == "print" ): self.add_message("misplaced-format-function", node=call_node) @utils.check_messages( "eval-used", "exec-used", "bad-reversed-sequence", "misplaced-format-function" ) def visit_call(self, node): """visit a Call node -> check if this is not a disallowed builtin call and check for * or ** use """ self._check_misplaced_format_function(node) if isinstance(node.func, astroid.Name): name = node.func.name # ignore the name if it's not a builtin (i.e. not defined in the # locals nor globals scope) if not (name in node.frame() or name in node.root()): if name == "exec": self.add_message("exec-used", node=node) elif name == "reversed": self._check_reversed(node) elif name == "eval": self.add_message("eval-used", node=node) @utils.check_messages("assert-on-tuple", "assert-on-string-literal") def visit_assert(self, node): """check whether assert is used on a tuple or string literal.""" if ( node.fail is None and isinstance(node.test, astroid.Tuple) and len(node.test.elts) == 2 ): self.add_message("assert-on-tuple", node=node) if isinstance(node.test, astroid.Const) and isinstance(node.test.value, str): if node.test.value: when = "never" else: when = "always" self.add_message("assert-on-string-literal", node=node, args=(when,)) @utils.check_messages("duplicate-key") def visit_dict(self, node): """check duplicate key in dictionary""" keys = set() for k, _ in node.items: if isinstance(k, astroid.Const): key = k.value if key in keys: self.add_message("duplicate-key", node=node, args=key) keys.add(key) def visit_tryfinally(self, node): """update try...finally flag""" self._tryfinallys.append(node) def leave_tryfinally(self, node): # pylint: disable=unused-argument """update try...finally flag""" self._tryfinallys.pop() def _check_unreachable(self, node): """check unreachable code""" unreach_stmt = node.next_sibling() if unreach_stmt is not None: self.add_message("unreachable", node=unreach_stmt) def _check_not_in_finally(self, node, node_name, breaker_classes=()): """check that a node is not inside a finally clause of a try...finally statement. If we found before a try...finally bloc a parent which its type is in breaker_classes, we skip the whole check.""" # if self._tryfinallys is empty, we're not an in try...finally block if not self._tryfinallys: return # the node could be a grand-grand...-children of the try...finally _parent = node.parent _node = node while _parent and not isinstance(_parent, breaker_classes): if hasattr(_parent, "finalbody") and _node in _parent.finalbody: self.add_message("lost-exception", node=node, args=node_name) return _node = _parent _parent = _node.parent def _check_reversed(self, node): """ check that the argument to `reversed` is a sequence """ try: argument = utils.safe_infer(utils.get_argument_from_call(node, position=0)) except utils.NoSuchArgumentError: pass else: if argument is astroid.Uninferable: return if argument is None: # Nothing was inferred. # Try to see if we have iter(). if isinstance(node.args[0], astroid.Call): try: func = next(node.args[0].func.infer()) except astroid.InferenceError: return if getattr( func, "name", None ) == "iter" and utils.is_builtin_object(func): self.add_message("bad-reversed-sequence", node=node) return if isinstance(argument, (astroid.List, astroid.Tuple)): return if isinstance(argument, astroid.Instance): if any( ancestor.name == "dict" and utils.is_builtin_object(ancestor) for ancestor in itertools.chain( (argument._proxied,), argument._proxied.ancestors() ) ): # Mappings aren't accepted by reversed(), unless # they provide explicitly a __reversed__ method. try: argument.locals[REVERSED_PROTOCOL_METHOD] except KeyError: self.add_message("bad-reversed-sequence", node=node) return if hasattr(argument, "getattr"): # everything else is not a proper sequence for reversed() for methods in REVERSED_METHODS: for meth in methods: try: argument.getattr(meth) except astroid.NotFoundError: break else: break else: self.add_message("bad-reversed-sequence", node=node) else: self.add_message("bad-reversed-sequence", node=node) @utils.check_messages("confusing-with-statement") def visit_with(self, node): # a "with" statement with multiple managers corresponds # to one AST "With" node with multiple items pairs = node.items if pairs: for prev_pair, pair in zip(pairs, pairs[1:]): if isinstance(prev_pair[1], astroid.AssignName) and ( pair[1] is None and not isinstance(pair[0], astroid.Call) ): # Don't emit a message if the second is a function call # there's no way that can be mistaken for a name assignment. # If the line number doesn't match # we assume it's a nested "with". self.add_message("confusing-with-statement", node=node) def _check_self_assigning_variable(self, node): # Detect assigning to the same variable. scope = node.scope() scope_locals = scope.locals rhs_names = [] targets = node.targets if isinstance(targets[0], astroid.Tuple): if len(targets) != 1: # A complex assignment, so bail out early. return targets = targets[0].elts if len(targets) == 1: # Unpacking a variable into the same name. return if isinstance(node.value, astroid.Name): if len(targets) != 1: return rhs_names = [node.value] elif isinstance(node.value, astroid.Tuple): rhs_count = len(node.value.elts) if len(targets) != rhs_count or rhs_count == 1: return rhs_names = node.value.elts for target, lhs_name in zip(targets, rhs_names): if not isinstance(lhs_name, astroid.Name): continue if not isinstance(target, astroid.AssignName): continue if isinstance(scope, astroid.ClassDef) and target.name in scope_locals: # Check that the scope is different than a class level, which is usually # a pattern to expose module level attributes as class level ones. continue if target.name == lhs_name.name: self.add_message( "self-assigning-variable", args=(target.name,), node=target ) def _check_redeclared_assign_name(self, targets): dummy_variables_rgx = lint_utils.get_global_option( self, "dummy-variables-rgx", default=None ) for target in targets: if not isinstance(target, astroid.Tuple): continue found_names = [] for element in target.elts: if isinstance(element, astroid.Tuple): self._check_redeclared_assign_name([element]) elif isinstance(element, astroid.AssignName) and element.name != "_": if dummy_variables_rgx and dummy_variables_rgx.match(element.name): return found_names.append(element.name) names = collections.Counter(found_names) for name, count in names.most_common(): if count > 1: self.add_message( "redeclared-assigned-name", args=(name,), node=target ) @utils.check_messages("self-assigning-variable", "redeclared-assigned-name") def visit_assign(self, node): self._check_self_assigning_variable(node) self._check_redeclared_assign_name(node.targets) @utils.check_messages("redeclared-assigned-name") def visit_for(self, node): self._check_redeclared_assign_name([node.target]) KNOWN_NAME_TYPES = { "module", "const", "class", "function", "method", "attr", "argument", "variable", "class_attribute", "class_const", "inlinevar", } HUMAN_READABLE_TYPES = { "module": "module", "const": "constant", "class": "class", "function": "function", "method": "method", "attr": "attribute", "argument": "argument", "variable": "variable", "class_attribute": "class attribute", "class_const": "class constant", "inlinevar": "inline iteration", } DEFAULT_NAMING_STYLES = { "module": "snake_case", "const": "UPPER_CASE", "class": "PascalCase", "function": "snake_case", "method": "snake_case", "attr": "snake_case", "argument": "snake_case", "variable": "snake_case", "class_attribute": "any", "class_const": "UPPER_CASE", "inlinevar": "any", } def _create_naming_options(): name_options = [] for name_type in sorted(KNOWN_NAME_TYPES): human_readable_name = HUMAN_READABLE_TYPES[name_type] default_style = DEFAULT_NAMING_STYLES[name_type] name_type = name_type.replace("_", "-") name_options.append( ( f"{name_type}-naming-style", { "default": default_style, "type": "choice", "choices": list(NAMING_STYLES.keys()), "metavar": "