Edit File: typecheck.py
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE # Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt """Try to find more bugs in the code using astroid inference capabilities.""" from __future__ import annotations import heapq import itertools import operator import re import shlex import sys import types from collections.abc import Callable, Iterable, Iterator, Sequence from functools import singledispatch from re import Pattern from typing import TYPE_CHECKING, Any, TypeVar, Union import astroid import astroid.exceptions import astroid.helpers from astroid import arguments, bases, nodes, util from astroid.typing import InferenceResult, SuccessfulInferenceResult from pylint.checkers import BaseChecker, utils from pylint.checkers.utils import ( decorated_with, decorated_with_property, has_known_bases, is_builtin_object, is_comprehension, is_hashable, is_inside_abstract_class, is_iterable, is_mapping, is_module_ignored, is_node_in_type_annotation_context, is_none, is_overload_stub, is_postponed_evaluation_enabled, is_super, node_ignores_exception, only_required_for_messages, safe_infer, supports_delitem, supports_getitem, supports_membership_test, supports_setitem, ) from pylint.constants import PY310_PLUS from pylint.interfaces import HIGH, INFERENCE from pylint.typing import MessageDefinitionTuple if sys.version_info >= (3, 8): from functools import cached_property from typing import Literal else: from astroid.decorators import cachedproperty as cached_property from typing_extensions import Literal if TYPE_CHECKING: from pylint.lint import PyLinter CallableObjects = Union[ bases.BoundMethod, bases.UnboundMethod, nodes.FunctionDef, nodes.Lambda, nodes.ClassDef, ] _T = TypeVar("_T") STR_FORMAT = {"builtins.str.format"} ASYNCIO_COROUTINE = "asyncio.coroutines.coroutine" BUILTIN_TUPLE = "builtins.tuple" TYPE_ANNOTATION_NODES_TYPES = ( nodes.AnnAssign, nodes.Arguments, nodes.FunctionDef, ) class VERSION_COMPATIBLE_OVERLOAD: pass VERSION_COMPATIBLE_OVERLOAD_SENTINEL = VERSION_COMPATIBLE_OVERLOAD() def _unflatten(iterable: Iterable[_T]) -> Iterator[_T]: for index, elem in enumerate(iterable): if isinstance(elem, Sequence) and not isinstance(elem, str): yield from _unflatten(elem) elif elem and not index: # We're interested only in the first element. yield elem # type: ignore[misc] def _flatten_container(iterable: Iterable[_T]) -> Iterator[_T]: # Flatten nested containers into a single iterable for item in iterable: if isinstance(item, (list, tuple, types.GeneratorType)): yield from _flatten_container(item) else: yield item def _is_owner_ignored( owner: SuccessfulInferenceResult, attrname: str | None, ignored_classes: Iterable[str], ignored_modules: Iterable[str], ) -> bool: """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*. """ if is_module_ignored(owner.root(), ignored_modules): return True # Match against ignored classes. ignored_classes = set(ignored_classes) qname = owner.qname() if hasattr(owner, "qname") else "" return any(ignore in (attrname, qname) for ignore in ignored_classes) @singledispatch def _node_names(node: SuccessfulInferenceResult) -> Iterable[str]: if not hasattr(node, "locals"): return [] return node.locals.keys() # type: ignore[no-any-return] @_node_names.register(nodes.ClassDef) @_node_names.register(astroid.Instance) def _(node: nodes.ClassDef | bases.Instance) -> Iterable[str]: values = itertools.chain(node.instance_attrs.keys(), node.locals.keys()) try: mro = node.mro()[1:] except (NotImplementedError, TypeError, astroid.MroError): mro = node.ancestors() other_values = [value for cls in mro for value in _node_names(cls)] return itertools.chain(values, other_values) def _string_distance(seq1: str, seq2: str) -> int: seq2_length = len(seq2) row = list(range(1, seq2_length + 1)) + [0] for seq1_index, seq1_char in enumerate(seq1): last_row = row row = [0] * seq2_length + [seq1_index + 1] for seq2_index, seq2_char in enumerate(seq2): row[seq2_index] = min( last_row[seq2_index] + 1, row[seq2_index - 1] + 1, last_row[seq2_index - 1] + (seq1_char != seq2_char), ) return row[seq2_length - 1] def _similar_names( owner: SuccessfulInferenceResult, attrname: str | None, distance_threshold: int, max_choices: int, ) -> list[str]: """Given an owner and a name, try to find similar names. The similar names are searched given a distance metric and only a given number of choices will be returned. """ possible_names: list[tuple[str, int]] = [] names = _node_names(owner) for name in names: if name == attrname: continue distance = _string_distance(attrname or "", name) if distance <= distance_threshold: possible_names.append((name, distance)) # Now get back the values with a minimum, up to the given # limit or choices. picked = [ name for (name, _) in heapq.nsmallest( max_choices, possible_names, key=operator.itemgetter(1) ) ] return sorted(picked) def _missing_member_hint( owner: SuccessfulInferenceResult, attrname: str | None, distance_threshold: int, max_choices: int, ) -> str: names = _similar_names(owner, attrname, distance_threshold, max_choices) if not names: # No similar name. return "" names = [repr(name) for name in names] if len(names) == 1: names_hint = ", ".join(names) else: names_hint = f"one of {', '.join(names[:-1])} or {names[-1]}" return f"; maybe {names_hint}?" MSGS: dict[str, MessageDefinitionTuple] = { "E1101": ( "%s %r has no %r member%s", "no-member", "Used when a variable is accessed for a nonexistent member.", {"old_names": [("E1103", "maybe-no-member")]}, ), "I1101": ( "%s %r has no %r member%s, but source is unavailable. Consider " "adding this module to extension-pkg-allow-list if you want " "to perform analysis based on run-time introspection of living objects.", "c-extension-no-member", "Used when a variable is accessed for non-existent member of C " "extension. Due to unavailability of source static analysis is impossible, " "but it may be performed by introspecting living objects in run-time.", ), "E1102": ( "%s is not callable", "not-callable", "Used when an object being called has been inferred to a non " "callable object.", ), "E1111": ( "Assigning result of a function call, where the function has no 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." ), ), "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 result of a function call, where the function 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", "old-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 a 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 or __class_getitem__ for a class).", ), "E1137": ( "%r does not support item assignment", "unsupported-assignment-operation", "Emitted when an object does not support item assignment " "(i.e. doesn't define __setitem__ method).", ), "E1138": ( "%r does not support item deletion", "unsupported-delete-operation", "Emitted when an object does not support item deletion " "(i.e. doesn't define __delitem__ method).", ), "E1139": ( "Invalid metaclass %r used", "invalid-metaclass", "Emitted whenever we can detect that a class is using, " "as a metaclass, something which might be invalid for using as " "a metaclass.", ), "E1141": ( "Unpacking a dictionary in iteration without calling .items()", "dict-iter-missing-items", "Emitted when trying to iterate through a dict without calling .items()", ), "E1142": ( "'await' should be used within an async function", "await-outside-async", "Emitted when await is used outside an async function.", ), "E1143": ( "'%s' is unhashable and can't be used as a %s in a %s", "unhashable-member", "Emitted when a dict key or set member is not hashable " "(i.e. doesn't define __hash__ method).", {"old_names": [("E1140", "unhashable-dict-key")]}, ), "E1144": ( "Slice step cannot be 0", "invalid-slice-step", "Used when a slice step is 0 and the object doesn't implement " "a custom __getitem__ method.", ), "W1113": ( "Keyword argument before variable positional arguments list " "in the definition of %s function", "keyword-arg-before-vararg", "When defining a keyword argument before variable positional arguments, one can " "end up in having multiple values passed for the aforementioned parameter in " "case the method is called with keyword arguments.", ), "W1114": ( "Positional arguments appear to be out of order", "arguments-out-of-order", "Emitted when the caller's argument names fully match the parameter " "names in the function signature but do not have the same order.", ), "W1115": ( "Non-string value assigned to __name__", "non-str-assignment-to-dunder-name", "Emitted when a non-string value is assigned to __name__", ), "W1116": ( "Second argument of isinstance is not a type", "isinstance-second-argument-not-valid-type", "Emitted when the second argument of an isinstance call is not a type.", ), } # builtin sequence types in Python 2 and 3. SEQUENCE_TYPES = { "str", "unicode", "list", "tuple", "bytearray", "xrange", "range", "bytes", "memoryview", } def _emit_no_member( node: nodes.Attribute | nodes.AssignAttr | nodes.DelAttr, owner: InferenceResult, owner_name: str | None, mixin_class_rgx: Pattern[str], ignored_mixins: bool = True, ignored_none: bool = True, ) -> bool: """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. * The node is guarded behind and `IF` or `IFExp` node """ # pylint: disable = too-many-return-statements, too-many-branches if node_ignores_exception(node, AttributeError): return False if ignored_none and isinstance(owner, nodes.Const) and owner.value is None: return False if is_super(owner) or getattr(owner, "type", None) == "metaclass": return False if owner_name and ignored_mixins and mixin_class_rgx.match(owner_name): return False if isinstance(owner, nodes.FunctionDef) and ( owner.decorators or owner.is_abstract() ): return False if isinstance(owner, (astroid.Instance, nodes.ClassDef)): if owner.has_dynamic_getattr(): # Issue #2565: Don't ignore enums, as they have a `__getattr__` but it's not # invoked at this point. try: metaclass = owner.metaclass() except astroid.MroError: return False if metaclass: # Renamed in Python 3.10 to `EnumType` if metaclass.qname() in {"enum.EnumMeta", "enum.EnumType"}: return not _enum_has_attribute(owner, node) return False return False if not has_known_bases(owner): return False # Exclude typed annotations, since these might actually exist # at some point during the runtime of the program. if utils.is_attribute_typed_annotation(owner, node.attrname): return False if isinstance(owner, astroid.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 (astroid.MroError, astroid.SuperError): return False if not all(has_known_bases(base) for base in owner.type.mro()): return False if isinstance(owner, nodes.Module): try: owner.getattr("__getattr__") return False except astroid.NotFoundError: pass if owner_name and node.attrname.startswith("_" + owner_name): # Test if an attribute has been mangled ('private' attribute) unmangled_name = node.attrname.split("_" + owner_name)[-1] try: if owner.getattr(unmangled_name, context=None) is not None: return False except astroid.NotFoundError: return True # Don't emit no-member if guarded behind `IF` or `IFExp` # * Walk up recursively until if statement is found. # * Check if condition can be inferred as `Const`, # would evaluate as `False`, # and whether the node is part of the `body`. # * Continue checking until scope of node is reached. scope: nodes.NodeNG = node.scope() node_origin: nodes.NodeNG = node parent: nodes.NodeNG = node.parent while parent != scope: if isinstance(parent, (nodes.If, nodes.IfExp)): inferred = safe_infer(parent.test) if ( # pylint: disable=too-many-boolean-expressions isinstance(inferred, nodes.Const) and inferred.bool_value() is False and ( isinstance(parent, nodes.If) and node_origin in parent.body or isinstance(parent, nodes.IfExp) and node_origin == parent.body ) ): return False node_origin, parent = parent, parent.parent return True def _get_all_attribute_assignments( node: nodes.FunctionDef, name: str | None = None ) -> set[str]: attributes: set[str] = set() for child in node.nodes_of_class((nodes.Assign, nodes.AnnAssign)): targets = [] if isinstance(child, nodes.Assign): targets = child.targets elif isinstance(child, nodes.AnnAssign): targets = [child.target] for assign_target in targets: if isinstance(assign_target, nodes.Tuple): targets.extend(assign_target.elts) continue if ( isinstance(assign_target, nodes.AssignAttr) and isinstance(assign_target.expr, nodes.Name) and (name is None or assign_target.expr.name == name) ): attributes.add(assign_target.attrname) return attributes def _enum_has_attribute( owner: astroid.Instance | nodes.ClassDef, node: nodes.Attribute ) -> bool: if isinstance(owner, astroid.Instance): enum_def = next( (b.parent for b in owner.bases if isinstance(b.parent, nodes.ClassDef)), None, ) if enum_def is None: # We don't inherit from anything, so try to find the parent # class definition and roll with that enum_def = node while enum_def is not None and not isinstance(enum_def, nodes.ClassDef): enum_def = enum_def.parent # If this blows, something is clearly wrong assert enum_def is not None, "enum_def unexpectedly None" else: enum_def = owner # Find __new__ and __init__ dunder_new = next((m for m in enum_def.methods() if m.name == "__new__"), None) dunder_init = next((m for m in enum_def.methods() if m.name == "__init__"), None) enum_attributes: set[str] = set() # Find attributes defined in __new__ if dunder_new: # Get the object returned in __new__ returned_obj_name = next( (c.value for c in dunder_new.get_children() if isinstance(c, nodes.Return)), None, ) if isinstance(returned_obj_name, nodes.Name): # Find all attribute assignments to the returned object enum_attributes |= _get_all_attribute_assignments( dunder_new, returned_obj_name.name ) # Find attributes defined in __init__ if dunder_init and dunder_init.body and dunder_init.args: # Grab the name referring to `self` from the function def enum_attributes |= _get_all_attribute_assignments( dunder_init, dunder_init.args.arguments[0].name ) return node.attrname in enum_attributes def _determine_callable( callable_obj: nodes.NodeNG, ) -> tuple[CallableObjects, int, str]: # TODO: The typing of the second return variable is actually Literal[0,1] # We need typing on astroid.NodeNG.implicit_parameters for this # TODO: The typing of the third return variable can be narrowed to a Literal # We need typing on astroid.NodeNG.type for this # Ordering is important, since BoundMethod is a subclass of UnboundMethod, # and Function inherits Lambda. parameters = 0 if hasattr(callable_obj, "implicit_parameters"): parameters = callable_obj.implicit_parameters() if isinstance(callable_obj, bases.BoundMethod): # Bound methods have an extra implicit 'self' argument. return callable_obj, parameters, callable_obj.type if isinstance(callable_obj, bases.UnboundMethod): return callable_obj, parameters, "unbound method" if isinstance(callable_obj, nodes.FunctionDef): return callable_obj, parameters, callable_obj.type if isinstance(callable_obj, nodes.Lambda): return callable_obj, parameters, "lambda" if isinstance(callable_obj, nodes.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 astroid.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 astroid.NotFoundError as e: raise ValueError from e else: callable_obj = new if not isinstance(callable_obj, nodes.FunctionDef): raise ValueError # both have an extra implicit 'cls'/'self' argument. return callable_obj, parameters, "constructor" raise ValueError def _has_parent_of_type( node: nodes.Call, node_type: nodes.Keyword | nodes.Starred, statement: nodes.Statement, ) -> bool: """Check if the given node has a parent of the given type.""" parent = node.parent while not isinstance(parent, node_type) and statement.parent_of(parent): parent = parent.parent return isinstance(parent, node_type) def _no_context_variadic_keywords(node: nodes.Call, scope: nodes.Lambda) -> bool: statement = node.statement(future=True) variadics = [] if ( isinstance(scope, nodes.Lambda) and not isinstance(scope, nodes.FunctionDef) or isinstance(statement, nodes.With) ): variadics = list(node.keywords or []) + node.kwargs elif isinstance(statement, (nodes.Return, nodes.Expr, nodes.Assign)) and isinstance( statement.value, nodes.Call ): call = statement.value variadics = list(call.keywords or []) + call.kwargs return _no_context_variadic(node, scope.args.kwarg, nodes.Keyword, variadics) def _no_context_variadic_positional(node: nodes.Call, scope: nodes.Lambda) -> bool: variadics = node.starargs + node.kwargs return _no_context_variadic(node, scope.args.vararg, nodes.Starred, variadics) def _no_context_variadic( node: nodes.Call, variadic_name: str | None, variadic_type: nodes.Keyword | nodes.Starred, variadics: list[nodes.Keyword | nodes.Starred], ) -> bool: """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. """ scope = node.scope() is_in_lambda_scope = not isinstance(scope, nodes.FunctionDef) and isinstance( scope, nodes.Lambda ) statement = node.statement(future=True) for name in statement.nodes_of_class(nodes.Name): if name.name != variadic_name: continue inferred = safe_infer(name) if isinstance(inferred, (nodes.List, nodes.Tuple)): length = len(inferred.elts) elif isinstance(inferred, nodes.Dict): length = len(inferred.items) else: continue if is_in_lambda_scope and isinstance(inferred.parent, nodes.Arguments): # The statement of the variadic will be the assignment itself, # so we need to go the lambda instead inferred_statement = inferred.parent.parent else: inferred_statement = inferred.statement(future=True) if not length and isinstance(inferred_statement, nodes.Lambda): is_in_starred_context = _has_parent_of_type(node, variadic_type, statement) used_as_starred_argument = any( variadic.value == name or variadic.value.parent_of(name) for variadic in variadics ) if is_in_starred_context or used_as_starred_argument: return True return False def _is_invalid_metaclass(metaclass: nodes.ClassDef) -> bool: mro = metaclass.mro() return not any(is_builtin_object(cls) and cls.name == "type" for cls in mro) def _infer_from_metaclass_constructor( cls: nodes.ClassDef, func: nodes.FunctionDef ) -> InferenceResult | None: """Try to infer what the given *func* constructor is building. :param astroid.FunctionDef func: A metaclass constructor. Metaclass definitions can be functions, which should accept three arguments, the name of the class, the bases of the class and the attributes. The function could return anything, but usually it should be a proper metaclass. :param astroid.ClassDef cls: The class for which the *func* parameter should generate a metaclass. :returns: The class generated by the function or None, if we couldn't infer it. :rtype: astroid.ClassDef """ context = astroid.context.InferenceContext() class_bases = nodes.List() class_bases.postinit(elts=cls.bases) attrs = nodes.Dict() local_names = [(name, values[-1]) for name, values in cls.locals.items()] attrs.postinit(local_names) builder_args = nodes.Tuple() builder_args.postinit([cls.name, class_bases, attrs]) context.callcontext = astroid.context.CallContext(builder_args) try: inferred = next(func.infer_call_result(func, context), None) except astroid.InferenceError: return None return inferred or None def _is_c_extension(module_node: InferenceResult) -> bool: return ( isinstance(module_node, nodes.Module) and not astroid.modutils.is_stdlib_module(module_node.name) and not module_node.fully_defined() ) def _is_invalid_isinstance_type(arg: nodes.NodeNG) -> bool: # Return True if we are sure that arg is not a type if PY310_PLUS and isinstance(arg, nodes.BinOp) and arg.op == "|": return any( _is_invalid_isinstance_type(elt) and not is_none(elt) for elt in (arg.left, arg.right) ) inferred = utils.safe_infer(arg) if not inferred: # Cannot infer it so skip it. return False if isinstance(inferred, nodes.Tuple): return any(_is_invalid_isinstance_type(elt) for elt in inferred.elts) if isinstance(inferred, nodes.ClassDef): return False if isinstance(inferred, astroid.Instance) and inferred.qname() == BUILTIN_TUPLE: return False if PY310_PLUS and isinstance(inferred, bases.UnionType): return any( _is_invalid_isinstance_type(elt) and not is_none(elt) for elt in (inferred.left, inferred.right) ) return True class TypeChecker(BaseChecker): """Try to find bugs in the code using type inference.""" # configuration section name name = "typecheck" # messages msgs = MSGS # configuration options options = ( ( "ignore-on-opaque-inference", { "default": True, "type": "yn", "metavar": "<y or n>", "help": "This flag controls whether pylint should warn about " "no-member and similar checks whenever an opaque object " "is returned when inferring. The inference can return " "multiple potential results while evaluating a Python object, " "but some branches might not be evaluated, which results in " "partial inference. In that case, it might be useful to still emit " "no-member and other checks for the rest of the inferred objects.", }, ), ( "mixin-class-rgx", { "default": ".*[Mm]ixin", "type": "regexp", "metavar": "<regexp>", "help": "Regex pattern to define which classes are considered mixins.", }, ), ( "ignore-mixin-members", { "default": True, "type": "yn", "metavar": "<y or n>", "help": "Tells whether missing members accessed in mixin " "class should be ignored. A class is considered mixin if its name matches " "the mixin-class-rgx option.", "kwargs": {"new_names": ["ignore-checks-for-mixin"]}, }, ), ( "ignored-checks-for-mixins", { "default": [ "no-member", "not-async-context-manager", "not-context-manager", "attribute-defined-outside-init", ], "type": "csv", "metavar": "<list of messages names>", "help": "List of symbolic message names to ignore for Mixin members.", }, ), ( "ignore-none", { "default": True, "type": "yn", "metavar": "<y or n>", "help": "Tells whether to warn about missing members when the owner " "of the attribute is inferred to be None.", }, ), # the defaults here are *stdlib* names that (almost) always # lead to false positives, since their idiomatic use is # 'too dynamic' for pylint to grok. ( "ignored-classes", { "default": ( "optparse.Values", "thread._local", "_thread._local", "argparse.Namespace", ), "type": "csv", "metavar": "<members names>", "help": "List of class names for which member attributes " "should not be checked (useful for classes with " "dynamically set attributes). This supports " "the use of qualified names.", }, ), ( "generated-members", { "default": (), "type": "string", "metavar": "<members names>", "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.", }, ), ( "contextmanager-decorators", { "default": ["contextlib.contextmanager"], "type": "csv", "metavar": "<decorator names>", "help": "List of decorators that produce context managers, " "such as contextlib.contextmanager. Add to this list " "to register other decorators that produce valid " "context managers.", }, ), ( "missing-member-hint-distance", { "default": 1, "type": "int", "metavar": "<member hint edit distance>", "help": "The minimum edit distance a name should have in order " "to be considered a similar match for a missing member name.", }, ), ( "missing-member-max-choices", { "default": 1, "type": "int", "metavar": "<member hint max choices>", "help": "The total number of similar names that should be taken in " "consideration when showing a hint for a missing member.", }, ), ( "missing-member-hint", { "default": True, "type": "yn", "metavar": "<missing member hint>", "help": "Show a hint with possible names when a member name was not " "found. The aspect of finding the hint is based on edit distance.", }, ), ( "signature-mutators", { "default": [], "type": "csv", "metavar": "<decorator names>", "help": "List of decorators that change the signature of " "a decorated function.", }, ), ) def open(self) -> None: py_version = self.linter.config.py_version self._py310_plus = py_version >= (3, 10) self._mixin_class_rgx = self.linter.config.mixin_class_rgx @cached_property def _suggestion_mode(self) -> bool: return self.linter.config.suggestion_mode # type: ignore[no-any-return] @cached_property def _compiled_generated_members(self) -> tuple[Pattern[str], ...]: # do this lazily 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}') generated_members = self.linter.config.generated_members if isinstance(generated_members, str): gen = shlex.shlex(generated_members) gen.whitespace += "," gen.wordchars += r"[]-+\.*?()|" generated_members = tuple(tok.strip('"') for tok in gen) return tuple(re.compile(exp) for exp in generated_members) @only_required_for_messages("keyword-arg-before-vararg") def visit_functiondef(self, node: nodes.FunctionDef) -> None: # check for keyword arg before varargs. if node.args.vararg and node.args.defaults: # When `positional-only` parameters are present then only # `positional-or-keyword` parameters are checked. I.e: # >>> def name(pos_only_params, /, pos_or_keyword_params, *args): ... if node.args.posonlyargs and not node.args.args: return self.add_message("keyword-arg-before-vararg", node=node, args=(node.name)) visit_asyncfunctiondef = visit_functiondef @only_required_for_messages("invalid-metaclass") def visit_classdef(self, node: nodes.ClassDef) -> None: def _metaclass_name(metaclass: InferenceResult) -> str | None: # pylint: disable=unidiomatic-typecheck if isinstance(metaclass, (nodes.ClassDef, nodes.FunctionDef)): return metaclass.name # type: ignore[no-any-return] if type(metaclass) is bases.Instance: # Really do mean type, not isinstance, since subclasses of bases.Instance # like Const or Dict should use metaclass.as_string below. return str(metaclass) return metaclass.as_string() # type: ignore[no-any-return] metaclass = node.declared_metaclass() if not metaclass: return if isinstance(metaclass, nodes.FunctionDef): # Try to infer the result. metaclass = _infer_from_metaclass_constructor(node, metaclass) if not metaclass: # Don't do anything if we cannot infer the result. return if isinstance(metaclass, nodes.ClassDef): if _is_invalid_metaclass(metaclass): self.add_message( "invalid-metaclass", node=node, args=(_metaclass_name(metaclass),) ) else: self.add_message( "invalid-metaclass", node=node, args=(_metaclass_name(metaclass),) ) def visit_assignattr(self, node: nodes.AssignAttr) -> None: if isinstance(node.assign_type(), nodes.AugAssign): self.visit_attribute(node) def visit_delattr(self, node: nodes.DelAttr) -> None: self.visit_attribute(node) # pylint: disable = too-many-branches @only_required_for_messages("no-member", "c-extension-no-member") def visit_attribute( self, node: nodes.Attribute | nodes.AssignAttr | nodes.DelAttr ) -> None: """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 """ if any( pattern.match(name) for name in (node.attrname, node.as_string()) for pattern in self._compiled_generated_members ): return if is_postponed_evaluation_enabled(node) and is_node_in_type_annotation_context( node ): return try: inferred = list(node.expr.infer()) except astroid.InferenceError: return # list of (node, nodename) which are missing the attribute missingattr: set[tuple[SuccessfulInferenceResult, str | None]] = set() non_opaque_inference_results: list[SuccessfulInferenceResult] = [ owner for owner in inferred if not isinstance(owner, (nodes.Unknown, util.UninferableBase)) ] if ( len(non_opaque_inference_results) != len(inferred) and self.linter.config.ignore_on_opaque_inference ): # There is an ambiguity in the inference. Since we can't # make sure that we won't emit a false positive, we just stop # whenever the inference returns an opaque inference object. return for owner in non_opaque_inference_results: name = getattr(owner, "name", None) if _is_owner_ignored( owner, name, self.linter.config.ignored_classes, self.linter.config.ignored_modules, ): continue qualname = f"{owner.pytype()}.{node.attrname}" if any( pattern.match(qualname) for pattern in self._compiled_generated_members ): return try: attr_nodes = owner.getattr(node.attrname) except AttributeError: continue except astroid.DuplicateBasesError: continue except astroid.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._mixin_class_rgx, ignored_mixins=( "no-member" in self.linter.config.ignored_checks_for_mixins ), ignored_none=self.linter.config.ignore_none, ): continue missingattr.add((owner, name)) continue else: for attr_node in attr_nodes: attr_parent = attr_node.parent # Skip augmented assignments try: if isinstance( attr_node.statement(future=True), nodes.AugAssign ) or ( isinstance(attr_parent, nodes.Assign) and utils.is_augmented_assign(attr_parent)[0] ): continue except astroid.exceptions.StatementMissing: break # Skip self-referencing assignments if attr_parent is node.parent: continue break else: 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 inferred 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) msg, hint = self._get_nomember_msgid_hint(node, owner) self.add_message( msg, node=node, args=(owner.display_type(), name, node.attrname, hint), confidence=INFERENCE, ) def _get_nomember_msgid_hint( self, node: nodes.Attribute | nodes.AssignAttr | nodes.DelAttr, owner: SuccessfulInferenceResult, ) -> tuple[Literal["c-extension-no-member", "no-member"], str]: suggestions_are_possible = self._suggestion_mode and isinstance( owner, nodes.Module ) if suggestions_are_possible and _is_c_extension(owner): msg = "c-extension-no-member" hint = "" else: msg = "no-member" if self.linter.config.missing_member_hint: hint = _missing_member_hint( owner, node.attrname, self.linter.config.missing_member_hint_distance, self.linter.config.missing_member_max_choices, ) else: hint = "" return msg, hint # type: ignore[return-value] @only_required_for_messages( "assignment-from-no-return", "assignment-from-none", "non-str-assignment-to-dunder-name", ) def visit_assign(self, node: nodes.Assign) -> None: """Process assignments in the AST.""" self._check_assignment_from_function_call(node) self._check_dundername_is_string(node) def _check_assignment_from_function_call(self, node: nodes.Assign) -> None: """When assigning to a function call, check that the function returns a valid value. """ if not isinstance(node.value, nodes.Call): return function_node = safe_infer(node.value.func) funcs = (nodes.FunctionDef, astroid.UnboundMethod, astroid.BoundMethod) if not isinstance(function_node, funcs): return # Unwrap to get the actual function node object if isinstance(function_node, astroid.BoundMethod) and isinstance( function_node._proxied, astroid.UnboundMethod ): function_node = function_node._proxied._proxied # Make sure that it's a valid function that we can analyze. # Ordered from less expensive to more expensive checks. if ( not function_node.is_function or function_node.decorators or self._is_ignored_function(function_node) ): return # Fix a false-negative for list.sort(), see issue #5722 if self._is_list_sort_method(node.value): self.add_message("assignment-from-none", node=node, confidence=INFERENCE) return if not function_node.root().fully_defined(): return return_nodes = list( function_node.nodes_of_class(nodes.Return, skip_klass=nodes.FunctionDef) ) if not return_nodes: self.add_message("assignment-from-no-return", node=node) else: for ret_node in return_nodes: if not ( isinstance(ret_node.value, nodes.Const) and ret_node.value.value is None or ret_node.value is None ): break else: self.add_message("assignment-from-none", node=node) @staticmethod def _is_ignored_function( function_node: nodes.FunctionDef | bases.UnboundMethod, ) -> bool: return ( isinstance(function_node, nodes.AsyncFunctionDef) or utils.is_error(function_node) or function_node.is_generator() or function_node.is_abstract(pass_is_abstract=False) ) @staticmethod def _is_list_sort_method(node: nodes.Call) -> bool: return ( isinstance(node.func, nodes.Attribute) and node.func.attrname == "sort" and isinstance(utils.safe_infer(node.func.expr), nodes.List) ) def _check_dundername_is_string(self, node: nodes.Assign) -> None: """Check a string is assigned to self.__name__.""" # Check the left-hand side of the assignment is <something>.__name__ lhs = node.targets[0] if not isinstance(lhs, nodes.AssignAttr): return if not lhs.attrname == "__name__": return # If the right-hand side is not a string rhs = node.value if isinstance(rhs, nodes.Const) and isinstance(rhs.value, str): return inferred = utils.safe_infer(rhs) if not inferred: return if not (isinstance(inferred, nodes.Const) and isinstance(inferred.value, str)): # Add the message self.add_message("non-str-assignment-to-dunder-name", node=node) def _check_uninferable_call(self, node: nodes.Call) -> None: """Check that the given uninferable Call node does not call an actual function. """ if not isinstance(node.func, nodes.Attribute): return # Look for properties. First, obtain # the lhs of the Attribute node and search the attribute # there. If that attribute is a property or a subclass of properties, # then most likely it's not callable. expr = node.func.expr klass = safe_infer(expr) if not isinstance(klass, astroid.Instance): return try: attrs = klass._proxied.getattr(node.func.attrname) except astroid.NotFoundError: return for attr in attrs: if not isinstance(attr, nodes.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): try: call_results = list(attr.infer_call_result(node)) except astroid.InferenceError: continue if all( isinstance(return_node, util.UninferableBase) for return_node in call_results ): # We were unable to infer return values of the call, skipping continue if any(return_node.callable() for return_node in call_results): # Only raise this issue if *all* the inferred values are not callable continue self.add_message("not-callable", node=node, args=node.func.as_string()) def _check_argument_order( self, node: nodes.Call, call_site: arguments.CallSite, called: CallableObjects, called_param_names: list[str | None], ) -> None: """Match the supplied argument names against the function parameters. Warn if some argument names are not in the same order as they are in the function signature. """ # Check for called function being an object instance function # If so, ignore the initial 'self' argument in the signature try: is_classdef = isinstance(called.parent, nodes.ClassDef) if is_classdef and called_param_names[0] == "self": called_param_names = called_param_names[1:] except IndexError: return try: # extract argument names, if they have names calling_parg_names = [p.name for p in call_site.positional_arguments] # Additionally, get names of keyword arguments to use in a full match # against parameters calling_kwarg_names = [ arg.name for arg in call_site.keyword_arguments.values() ] except AttributeError: # the type of arg does not provide a `.name`. In this case we # stop checking for out-of-order arguments because it is only relevant # for named variables. return # Don't check for ordering if there is an unmatched arg or param arg_set = set(calling_parg_names) | set(calling_kwarg_names) param_set = set(called_param_names) if arg_set != param_set: return # Warn based on the equality of argument ordering if calling_parg_names != called_param_names[: len(calling_parg_names)]: self.add_message("arguments-out-of-order", node=node, args=()) def _check_isinstance_args(self, node: nodes.Call) -> None: if len(node.args) != 2: # isinstance called with wrong number of args return second_arg = node.args[1] if _is_invalid_isinstance_type(second_arg): self.add_message( "isinstance-second-argument-not-valid-type", node=node, confidence=INFERENCE, ) # pylint: disable = too-many-branches, too-many-locals, too-many-statements def visit_call(self, node: nodes.Call) -> None: """Check that called functions/methods are inferred to callable objects, and that passed arguments match the parameters in the inferred function. """ called = safe_infer(node.func) self._check_not_callable(node, called) 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 if called.args.args is None: if called.name == "isinstance": # Verify whether second argument of isinstance is a valid type self._check_isinstance_args(node) # 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 # Build the set of keyword arguments, checking for duplicate keywords, # and count the positional arguments. call_site = astroid.arguments.CallSite.from_call(node) # 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 # Has the function signature changed in ways we cannot reliably detect? if hasattr(called, "decorators") and decorated_with( called, self.linter.config.signature_mutators ): return num_positional_args = len(call_site.positional_arguments) keyword_args = list(call_site.keyword_arguments.keys()) overload_function = is_overload_stub(called) # Determine if we don't have a context for our call and we use variadics. node_scope = node.scope() if isinstance(node_scope, (nodes.Lambda, nodes.FunctionDef)): has_no_context_positional_variadic = _no_context_variadic_positional( node, node_scope ) has_no_context_keywords_variadic = _no_context_variadic_keywords( node, node_scope ) else: has_no_context_positional_variadic = ( has_no_context_keywords_variadic ) = False # These are coming from the functools.partial implementation in astroid already_filled_positionals = getattr(called, "filled_positionals", 0) already_filled_keywords = getattr(called, "filled_keywords", {}) keyword_args += list(already_filled_keywords) num_positional_args += implicit_args + already_filled_positionals # Decrement `num_positional_args` by 1 when a function call is assigned to a class attribute # inside the class where the function is defined. # This avoids emitting `too-many-function-args` since `num_positional_args` # includes an implicit `self` argument which is not present in `called.args`. if ( isinstance(node.frame(), nodes.ClassDef) and isinstance(node.parent, (nodes.Assign, nodes.AnnAssign)) and isinstance(called, nodes.FunctionDef) and called in node.frame().body and num_positional_args > 0 ): num_positional_args -= 1 # Analyze the list of formal parameters. args = list(itertools.chain(called.args.posonlyargs or (), called.args.args)) num_mandatory_parameters = len(args) - len(called.args.defaults) parameters: list[tuple[tuple[str | None, nodes.NodeNG | None], bool]] = [] parameter_name_to_index = {} for i, arg in enumerate(args): if isinstance(arg, nodes.Tuple): name = None # Don't store any parameter names within the tuple, since those # are not assignable from keyword arguments. else: assert isinstance(arg, nodes.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, nodes.Keyword): name = arg.arg else: assert isinstance(arg, nodes.AssignName) name = arg.name kwparams[name] = [called.args.kw_defaults[i], False] self._check_argument_order( node, call_site, called, [p[0][0] for p in parameters] ) # 1. Match the positional arguments. for i in range(num_positional_args): if i < len(parameters): parameters[i] = (parameters[i][0], True) elif called.args.vararg is not None: # The remaining positional arguments get assigned to the *args # parameter. break elif not overload_function: # 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 hard-coded, 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() in STR_FORMAT): self.add_message( "redundant-keyword-arg", node=node, args=(keyword, callable_name), ) else: parameters[i] = (parameters[i][0], True) elif keyword in kwparams: if kwparams[keyword][1]: # 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 elif isinstance( called, nodes.FunctionDef ) and self._keyword_argument_is_in_all_decorator_returns(called, keyword): pass elif not overload_function: # 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] = (parameters[i][0], 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: display_name = "<tuple>" if name is None else repr(name) if not has_no_context_positional_variadic and not overload_function: self.add_message( "no-value-for-parameter", node=node, args=(display_name, callable_name), ) for name, val in kwparams.items(): defval, assigned = val if ( defval is None and not assigned and not has_no_context_keywords_variadic and not overload_function ): self.add_message( "missing-kwoa", node=node, args=(name, callable_name), confidence=INFERENCE, ) @staticmethod def _keyword_argument_is_in_all_decorator_returns( func: nodes.FunctionDef, keyword: str ) -> bool: """Check if the keyword argument exists in all signatures of the return values of all decorators of the function. """ if not func.decorators: return False for decorator in func.decorators.nodes: inferred = safe_infer(decorator) # If we can't infer the decorator we assume it satisfies consumes # the keyword, so we don't raise false positives if not inferred: return True # We only check arguments of function decorators if not isinstance(inferred, nodes.FunctionDef): return False for return_value in inferred.infer_call_result(): # infer_call_result() returns nodes.Const.None for None return values # so this also catches non-returning decorators if not isinstance(return_value, nodes.FunctionDef): return False # If the return value uses a kwarg the keyword will be consumed if return_value.args.kwarg: continue # Check if the keyword is another type of argument if return_value.args.is_argument(keyword): continue return False return True def _check_invalid_sequence_index(self, subscript: nodes.Subscript) -> None: # 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(subscript.value) if not isinstance( parent_type, (nodes.ClassDef, astroid.Instance) ) or not has_known_bases(parent_type): return None # 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. if subscript.ctx is astroid.Store: methodname = "__setitem__" elif subscript.ctx is astroid.Del: 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 = astroid.interpreter.dunder_lookup.lookup(parent_type, methodname) if isinstance(methods, util.UninferableBase): return None itemmethod = methods[0] except ( astroid.AttributeInferenceError, IndexError, ): return None if ( not isinstance(itemmethod, nodes.FunctionDef) or itemmethod.root().name != "builtins" or not itemmethod.parent or itemmethod.parent.frame().name not in SEQUENCE_TYPES ): return None index_type = safe_infer(subscript.slice) if index_type is None or isinstance(index_type, util.UninferableBase): return None # Constants must be of type int if isinstance(index_type, nodes.Const): if isinstance(index_type.value, int): return None # 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 None try: index_type.getattr("__index__") return None except astroid.NotFoundError: pass elif isinstance(index_type, nodes.Slice): # A slice can be present # here after inferring the index node, which could # be a `slice(...)` call for instance. return self._check_invalid_slice_index(index_type) # Anything else is an error self.add_message("invalid-sequence-index", node=subscript) return None def _check_not_callable( self, node: nodes.Call, inferred_call: nodes.NodeNG | None ) -> None: """Checks to see if the not-callable message should be emitted. Only functions, generators and objects defining __call__ are "callable" We ignore instances of descriptors since astroid cannot properly handle them yet """ # Handle uninferable calls if not inferred_call or inferred_call.callable(): self._check_uninferable_call(node) return if not isinstance(inferred_call, astroid.Instance): self.add_message("not-callable", node=node, args=node.func.as_string()) return # Don't emit if we can't make sure this object is callable. if not has_known_bases(inferred_call): return if inferred_call.parent and isinstance(inferred_call.scope(), nodes.ClassDef): # Ignore descriptor instances if "__get__" in inferred_call.locals: return # NamedTuple instances are callable if inferred_call.qname() == "typing.NamedTuple": return self.add_message("not-callable", node=node, args=node.func.as_string()) def _check_invalid_slice_index(self, node: nodes.Slice) -> None: # Check the type of each part of the slice invalid_slices_nodes: list[nodes.NodeNG] = [] 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 isinstance(index_type, util.UninferableBase): continue # Constants must be of type int or None if isinstance(index_type, nodes.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 astroid.NotFoundError: pass invalid_slices_nodes.append(index) invalid_slice_step = ( node.step and isinstance(node.step, nodes.Const) and node.step.value == 0 ) if not (invalid_slices_nodes or invalid_slice_step): return # Anything else is an error, unless the object that is indexed # is a custom object, which knows how to handle this kind of slices parent = node.parent if isinstance(parent, nodes.Subscript): inferred = safe_infer(parent.value) if inferred is None or isinstance(inferred, util.UninferableBase): # Don't know what this is return known_objects = ( nodes.List, nodes.Dict, nodes.Tuple, astroid.objects.FrozenSet, nodes.Set, ) if not ( isinstance(inferred, known_objects) or isinstance(inferred, nodes.Const) and inferred.pytype() in {"builtins.str", "builtins.bytes"} or isinstance(inferred, astroid.bases.Instance) and inferred.pytype() == "builtins.range" ): # Might be an instance that knows how to handle this slice object return for snode in invalid_slices_nodes: self.add_message("invalid-slice-index", node=snode) if invalid_slice_step: self.add_message("invalid-slice-step", node=node.step, confidence=HIGH) @only_required_for_messages("not-context-manager") def visit_with(self, node: nodes.With) -> None: for ctx_mgr, _ in node.items: context = astroid.context.InferenceContext() inferred = safe_infer(ctx_mgr, context=context) if inferred is None or isinstance(inferred, util.UninferableBase): continue if isinstance(inferred, astroid.bases.Generator): # Check if we are dealing with a function decorated # with contextlib.contextmanager. if decorated_with( inferred.parent, self.linter.config.contextmanager_decorators ): 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. # Retrieve node from all previously visited nodes in the # inference history context_path_names: Iterator[Any] = filter( None, _unflatten(context.path) ) inferred_paths = _flatten_container( safe_infer(path) for path in context_path_names ) for inferred_path in inferred_paths: if not inferred_path: continue scope = inferred_path.scope() if not isinstance(scope, nodes.FunctionDef): continue if decorated_with( scope, self.linter.config.contextmanager_decorators ): break else: self.add_message( "not-context-manager", node=node, args=(inferred.name,) ) else: try: inferred.getattr("__enter__") inferred.getattr("__exit__") except astroid.NotFoundError: if isinstance(inferred, astroid.Instance): # If we do not know the bases of this class, # just skip it. if not has_known_bases(inferred): continue # Just ignore mixin classes. if ( "not-context-manager" in self.linter.config.ignored_checks_for_mixins ): if inferred.name[-5:].lower() == "mixin": continue self.add_message( "not-context-manager", node=node, args=(inferred.name,) ) @only_required_for_messages("invalid-unary-operand-type") def visit_unaryop(self, node: nodes.UnaryOp) -> None: """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) @only_required_for_messages("unsupported-binary-operation") def visit_binop(self, node: nodes.BinOp) -> None: if node.op == "|": self._detect_unsupported_alternative_union_syntax(node) def _detect_unsupported_alternative_union_syntax(self, node: nodes.BinOp) -> None: """Detect if unsupported alternative Union syntax (PEP 604) was used.""" if self._py310_plus: # 310+ supports the new syntax return if isinstance( node.parent, TYPE_ANNOTATION_NODES_TYPES ) and not is_postponed_evaluation_enabled(node): # Use in type annotations only allowed if # postponed evaluation is enabled. self._check_unsupported_alternative_union_syntax(node) if isinstance( node.parent, ( nodes.Assign, nodes.Call, nodes.Keyword, nodes.Dict, nodes.Tuple, nodes.Set, nodes.List, nodes.BinOp, ), ): # Check other contexts the syntax might appear, but are invalid. # Make sure to filter context if postponed evaluation is enabled # and parent is allowed node type. allowed_nested_syntax = False if is_postponed_evaluation_enabled(node): parent_node = node.parent while True: if isinstance(parent_node, TYPE_ANNOTATION_NODES_TYPES): allowed_nested_syntax = True break parent_node = parent_node.parent if isinstance(parent_node, nodes.Module): break if not allowed_nested_syntax: self._check_unsupported_alternative_union_syntax(node) def _includes_version_compatible_overload(self, attrs: list[nodes.NodeNG]) -> bool: """Check if a set of overloads of an operator includes one that can be relied upon for our configured Python version. If we are running under a Python 3.10+ runtime but configured for pre-3.10 compatibility then Astroid will have inferred the existence of __or__ / __ror__ on builtins.type, but these aren't available in the configured version of Python. """ is_py310_builtin = all( isinstance(attr, (nodes.FunctionDef, astroid.BoundMethod)) and attr.parent.qname() == "builtins.type" for attr in attrs ) return not is_py310_builtin or self._py310_plus def _recursive_search_for_classdef_type( self, node: nodes.ClassDef, operation: Literal["__or__", "__ror__"] ) -> bool | VERSION_COMPATIBLE_OVERLOAD: if not isinstance(node, nodes.ClassDef): return False try: attrs = node.getattr(operation) except astroid.NotFoundError: return True if self._includes_version_compatible_overload(attrs): return VERSION_COMPATIBLE_OVERLOAD_SENTINEL return True def _check_unsupported_alternative_union_syntax(self, node: nodes.BinOp) -> None: """Check if left or right node is of type `type`. If either is, and doesn't support an or operator via a metaclass, infer that this is a mistaken attempt to use alternative union syntax when not supported. """ msg = "unsupported operand type(s) for |" left_obj = astroid.helpers.object_type(node.left) right_obj = astroid.helpers.object_type(node.right) left_is_type = self._recursive_search_for_classdef_type(left_obj, "__or__") if left_is_type is VERSION_COMPATIBLE_OVERLOAD_SENTINEL: return right_is_type = self._recursive_search_for_classdef_type(right_obj, "__ror__") if right_is_type is VERSION_COMPATIBLE_OVERLOAD_SENTINEL: return if left_is_type or right_is_type: self.add_message( "unsupported-binary-operation", args=msg, node=node, confidence=INFERENCE, ) # TODO: This check was disabled (by adding the leading underscore) # due to false positives several years ago - can we re-enable it? # https://github.com/PyCQA/pylint/issues/6359 @only_required_for_messages("unsupported-binary-operation") def _visit_binop(self, node: nodes.BinOp) -> None: """Detect TypeErrors for binary arithmetic operands.""" self._check_binop_errors(node) # TODO: This check was disabled (by adding the leading underscore) # due to false positives several years ago - can we re-enable it? # https://github.com/PyCQA/pylint/issues/6359 @only_required_for_messages("unsupported-binary-operation") def _visit_augassign(self, node: nodes.AugAssign) -> None: """Detect TypeErrors for augmented binary arithmetic operands.""" self._check_binop_errors(node) def _check_binop_errors(self, node: nodes.BinOp | nodes.AugAssign) -> None: for error in node.type_errors(): # Let the error customize its output. if any( isinstance(obj, nodes.ClassDef) and not has_known_bases(obj) for obj in (error.left_type, error.right_type) ): continue self.add_message("unsupported-binary-operation", args=str(error), node=node) def _check_membership_test(self, node: nodes.NodeNG) -> None: if is_inside_abstract_class(node): return if is_comprehension(node): return inferred = safe_infer(node) if inferred is None or isinstance(inferred, util.UninferableBase): return if not supports_membership_test(inferred): self.add_message( "unsupported-membership-test", args=node.as_string(), node=node ) @only_required_for_messages("unsupported-membership-test") def visit_compare(self, node: nodes.Compare) -> None: if len(node.ops) != 1: return op, right = node.ops[0] if op in {"in", "not in"}: self._check_membership_test(right) @only_required_for_messages("unhashable-member") def visit_dict(self, node: nodes.Dict) -> None: for k, _ in node.items: if not is_hashable(k): self.add_message( "unhashable-member", node=k, args=(k.as_string(), "key", "dict"), confidence=INFERENCE, ) @only_required_for_messages("unhashable-member") def visit_set(self, node: nodes.Set) -> None: for element in node.elts: if not is_hashable(element): self.add_message( "unhashable-member", node=element, args=(element.as_string(), "member", "set"), confidence=INFERENCE, ) @only_required_for_messages( "unsubscriptable-object", "unsupported-assignment-operation", "unsupported-delete-operation", "unhashable-member", "invalid-sequence-index", "invalid-slice-index", "invalid-slice-step", ) def visit_subscript(self, node: nodes.Subscript) -> None: self._check_invalid_sequence_index(node) supported_protocol: Callable[[Any, Any], bool] | None = None if isinstance(node.value, (nodes.ListComp, nodes.DictComp)): return if isinstance(node.value, nodes.Dict): # Assert dict key is hashable if not is_hashable(node.slice): self.add_message( "unhashable-member", node=node.value, args=(node.slice.as_string(), "key", "dict"), confidence=INFERENCE, ) if node.ctx == astroid.Load: supported_protocol = supports_getitem msg = "unsubscriptable-object" elif node.ctx == astroid.Store: supported_protocol = supports_setitem msg = "unsupported-assignment-operation" elif node.ctx == astroid.Del: supported_protocol = supports_delitem msg = "unsupported-delete-operation" if isinstance(node.value, nodes.SetComp): self.add_message(msg, args=node.value.as_string(), node=node.value) return if is_inside_abstract_class(node): return inferred = safe_infer(node.value) if inferred is None or isinstance(inferred, util.UninferableBase): return if getattr(inferred, "decorators", None): first_decorator = astroid.helpers.safe_infer(inferred.decorators.nodes[0]) if isinstance(first_decorator, nodes.ClassDef): inferred = first_decorator.instantiate_class() else: return # It would be better to handle function # decorators, but let's start slow. if ( supported_protocol and not supported_protocol(inferred, node) and not utils.in_type_checking_block(node) ): self.add_message(msg, args=node.value.as_string(), node=node.value) @only_required_for_messages("dict-items-missing-iter") def visit_for(self, node: nodes.For) -> None: if not isinstance(node.target, nodes.Tuple): # target is not a tuple return if not len(node.target.elts) == 2: # target is not a tuple of two elements return iterable = node.iter if not isinstance(iterable, nodes.Name): # it's not a bare variable return inferred = safe_infer(iterable) if not inferred: return if not isinstance(inferred, nodes.Dict): # the iterable is not a dict return if all(isinstance(i[0], nodes.Tuple) for i in inferred.items): # if all keys are tuples return self.add_message("dict-iter-missing-items", node=node) @only_required_for_messages("await-outside-async") def visit_await(self, node: nodes.Await) -> None: self._check_await_outside_coroutine(node) def _check_await_outside_coroutine(self, node: nodes.Await) -> None: node_scope = node.scope() while not isinstance(node_scope, nodes.Module): if isinstance(node_scope, nodes.AsyncFunctionDef): return if isinstance(node_scope, nodes.FunctionDef): break node_scope = node_scope.parent.scope() self.add_message("await-outside-async", node=node) 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. """ name = "typecheck" 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", ), } @staticmethod def _is_asyncio_coroutine(node: nodes.NodeNG) -> bool: if not isinstance(node, nodes.Call): return False inferred_func = safe_infer(node.func) if not isinstance(inferred_func, nodes.FunctionDef): return False if not inferred_func.decorators: return False for decorator in inferred_func.decorators.nodes: inferred_decorator = safe_infer(decorator) if not isinstance(inferred_decorator, nodes.FunctionDef): continue if inferred_decorator.qname() != ASYNCIO_COROUTINE: continue return True return False def _check_iterable(self, node: nodes.NodeNG, check_async: bool = False) -> None: if is_inside_abstract_class(node): return inferred = safe_infer(node) if not inferred or is_comprehension(inferred): return if not is_iterable(inferred, check_async=check_async): self.add_message("not-an-iterable", args=node.as_string(), node=node) def _check_mapping(self, node: nodes.NodeNG) -> None: if is_inside_abstract_class(node): return if isinstance(node, nodes.DictComp): return inferred = safe_infer(node) if inferred is None or isinstance(inferred, util.UninferableBase): return if not is_mapping(inferred): self.add_message("not-a-mapping", args=node.as_string(), node=node) @only_required_for_messages("not-an-iterable") def visit_for(self, node: nodes.For) -> None: self._check_iterable(node.iter) @only_required_for_messages("not-an-iterable") def visit_asyncfor(self, node: nodes.AsyncFor) -> None: self._check_iterable(node.iter, check_async=True) @only_required_for_messages("not-an-iterable") def visit_yieldfrom(self, node: nodes.YieldFrom) -> None: if self._is_asyncio_coroutine(node.value): return self._check_iterable(node.value) @only_required_for_messages("not-an-iterable", "not-a-mapping") def visit_call(self, node: nodes.Call) -> None: for stararg in node.starargs: self._check_iterable(stararg.value) for kwarg in node.kwargs: self._check_mapping(kwarg.value) @only_required_for_messages("not-an-iterable") def visit_listcomp(self, node: nodes.ListComp) -> None: for gen in node.generators: self._check_iterable(gen.iter, check_async=gen.is_async) @only_required_for_messages("not-an-iterable") def visit_dictcomp(self, node: nodes.DictComp) -> None: for gen in node.generators: self._check_iterable(gen.iter, check_async=gen.is_async) @only_required_for_messages("not-an-iterable") def visit_setcomp(self, node: nodes.SetComp) -> None: for gen in node.generators: self._check_iterable(gen.iter, check_async=gen.is_async) @only_required_for_messages("not-an-iterable") def visit_generatorexp(self, node: nodes.GeneratorExp) -> None: for gen in node.generators: self._check_iterable(gen.iter, check_async=gen.is_async) def register(linter: PyLinter) -> None: linter.register_checker(TypeChecker(linter)) linter.register_checker(IterableChecker(linter))