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fuchsia / third_party / github.com / pylint-dev / pylint / df5533f7d2d7bbe5092ddbbfb213c561fd263a64 / . / pylint / checkers / typecheck.py
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# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
# Copyright (c) https://github.com/pylint-dev/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
from collections.abc import Callable, Iterable
from functools import cached_property, singledispatch
from re import Pattern
from typing import TYPE_CHECKING, Any, Literal, Union
import astroid
import astroid.exceptions
import astroid.helpers
from astroid import arguments, bases, nodes, util
from astroid.nodes import _base_nodes
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 TYPE_CHECKING:
from pylint.lint import PyLinter
CallableObjects = Union[
bases.BoundMethod,
bases.UnboundMethod,
nodes.FunctionDef,
nodes.Lambda,
nodes.ClassDef,
]
STR_FORMAT = {"builtins.str.format"}
ASYNCIO_COROUTINE = "asyncio.coroutines.coroutine"
BUILTIN_TUPLE = "builtins.tuple"
TYPE_ANNOTATION_NODES_TYPES = (
nodes.AnnAssign,
nodes.Arguments,
nodes.FunctionDef,
)
BUILTINS_IMPLICIT_RETURN_NONE = {
"builtins.dict": {"clear", "update"},
"builtins.list": {
"append",
"clear",
"extend",
"insert",
"remove",
"reverse",
"sort",
},
"builtins.set": {
"add",
"clear",
"difference_update",
"discard",
"intersection_update",
"remove",
"symmetric_difference_update",
"update",
},
}
class VERSION_COMPATIBLE_OVERLOAD:
pass
VERSION_COMPATIBLE_OVERLOAD_SENTINEL = VERSION_COMPATIBLE_OVERLOAD()
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().qname(), 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.",
),
"W1117": (
"%r will be included in %r since a positional-only parameter with this name already exists",
"kwarg-superseded-by-positional-arg",
"Emitted when a function is called with a keyword argument that has the "
"same name as a positional-only parameter and the function contains a "
"keyword variadic parameter dict.",
),
}
# 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)):
# 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:
pass
else:
# Renamed in Python 3.10 to `EnumType`
if metaclass and metaclass.qname() in {"enum.EnumMeta", "enum.EnumType"}:
return not _enum_has_attribute(owner, node)
if owner.has_dynamic_getattr():
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: _base_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()
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()
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()
if not length and isinstance(
inferred_statement, (nodes.Lambda, nodes.FunctionDef)
):
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:
try:
mro = metaclass.mro()
except (astroid.DuplicateBasesError, astroid.InconsistentMroError):
return True
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(
lineno=0, col_offset=0, parent=None, end_lineno=0, end_col_offset=0
)
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, too-many-statements
@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:
# Avoid false positive in case a decorator supplies member.
if (
isinstance(owner, (astroid.FunctionDef, astroid.BoundMethod))
and owner.decorators
):
continue
# 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(), 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
# Handle builtins such as list.sort() or dict.update()
if self._is_builtin_no_return(node):
self.add_message(
"assignment-from-no-return", 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_builtin_no_return(node: nodes.Assign) -> bool:
return (
isinstance(node.value, nodes.Call)
and isinstance(node.value.func, nodes.Attribute)
and bool(inferred := utils.safe_infer(node.value.func.expr))
and isinstance(inferred, bases.Instance)
and node.value.func.attrname
in BUILTINS_IMPLICIT_RETURN_NONE.get(inferred.pytype(), ())
)
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(called, nodes.FunctionDef)
and called in node.frame().body
and num_positional_args > 0
and "builtins.staticmethod" not in called.decoratornames()
):
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):
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:
# Skip if `keyword` is the same name as a positional-only parameter
# and a `**kwargs` parameter exists.
if called.args.kwarg and keyword in [
arg.name for arg in called.args.posonlyargs
]:
self.add_message(
"kwarg-superseded-by-positional-arg",
node=node,
args=(keyword, f"**{called.args.kwarg}"),
confidence=HIGH,
)
continue
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(caller=None):
# 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.Context.Store:
methodname = "__setitem__"
elif subscript.ctx is astroid.Context.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
for inferred_path, _ in context.path:
if not inferred_path:
continue
if isinstance(inferred_path, nodes.Call):
scope = safe_infer(inferred_path.func)
else:
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/pylint-dev/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/pylint-dev/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.Context.Load:
supported_protocol = supports_getitem
msg = "unsubscriptable-object"
elif node.ctx == astroid.Context.Store:
supported_protocol = supports_setitem
msg = "unsupported-assignment-operation"
elif node.ctx == astroid.Context.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.util.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))