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# 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
"""Basic checker for Python code."""
from __future__ import annotations
import argparse
import collections
import itertools
import re
import sys
from collections.abc import Iterable
from enum import Enum, auto
from re import Pattern
from typing import TYPE_CHECKING, Tuple
import astroid
from astroid import nodes
from pylint import constants, interfaces
from pylint.checkers import utils
from pylint.checkers.base.basic_checker import _BasicChecker
from pylint.checkers.base.name_checker.naming_style import (
KNOWN_NAME_TYPES,
KNOWN_NAME_TYPES_WITH_STYLE,
NAMING_STYLES,
_create_naming_options,
)
from pylint.checkers.utils import is_property_deleter, is_property_setter
from pylint.typing import Options
if TYPE_CHECKING:
from pylint.lint.pylinter import PyLinter
_BadNamesTuple = Tuple[nodes.NodeNG, str, str, interfaces.Confidence]
# Default patterns for name types that do not have styles
DEFAULT_PATTERNS = {
"typevar": re.compile(
r"^_{0,2}(?!T[A-Z])(?:[A-Z]+|(?:[A-Z]+[a-z]+)+T?(?<!Type))(?:_co(?:ntra)?)?$"
),
"typealias": re.compile(
r"^_{0,2}(?!T[A-Z]|Type)[A-Z]+[a-z0-9]+(?:[A-Z][a-z0-9]+)*$"
),
}
BUILTIN_PROPERTY = "builtins.property"
TYPE_VAR_QNAME = frozenset(
(
"typing.TypeVar",
"typing_extensions.TypeVar",
)
)
class TypeVarVariance(Enum):
invariant = auto()
covariant = auto()
contravariant = auto()
double_variant = auto()
def _get_properties(config: argparse.Namespace) -> tuple[set[str], set[str]]:
"""Returns a tuple of property classes and names.
Property classes are fully qualified, such as 'abc.abstractproperty' and
property names are the actual names, such as 'abstract_property'.
"""
property_classes = {BUILTIN_PROPERTY}
property_names: set[str] = set() # Not returning 'property', it has its own check.
if config is not None:
property_classes.update(config.property_classes)
property_names.update(
prop.rsplit(".", 1)[-1] for prop in config.property_classes
)
return property_classes, property_names
def _redefines_import(node: nodes.AssignName) -> bool:
"""Detect that the given node (AssignName) is inside an
exception handler and redefines an import from the tryexcept body.
Returns True if the node redefines an import, False otherwise.
"""
current = node
while current and not isinstance(current.parent, nodes.ExceptHandler):
current = current.parent
if not current or not utils.error_of_type(current.parent, ImportError):
return False
try_block = current.parent.parent
for import_node in try_block.nodes_of_class((nodes.ImportFrom, nodes.Import)):
for name, alias in import_node.names:
if alias:
if alias == node.name:
return True
elif name == node.name:
return True
return False
def _determine_function_name_type(
node: nodes.FunctionDef, config: argparse.Namespace
) -> str:
"""Determine the name type whose regex the function's name should match.
:param node: A function node.
:param config: Configuration from which to pull additional property classes.
:returns: One of ('function', 'method', 'attr')
"""
property_classes, property_names = _get_properties(config)
if not node.is_method():
return "function"
if is_property_setter(node) or is_property_deleter(node):
# If the function is decorated using the prop_method.{setter,getter}
# form, treat it like an attribute as well.
return "attr"
decorators = node.decorators.nodes if node.decorators else []
for decorator in decorators:
# If the function is a property (decorated with @property
# or @abc.abstractproperty), the name type is 'attr'.
if isinstance(decorator, nodes.Name) or (
isinstance(decorator, nodes.Attribute)
and decorator.attrname in property_names
):
inferred = utils.safe_infer(decorator)
if (
inferred
and hasattr(inferred, "qname")
and inferred.qname() in property_classes
):
return "attr"
return "method"
# Name categories that are always consistent with all naming conventions.
EXEMPT_NAME_CATEGORIES = {"exempt", "ignore"}
def _is_multi_naming_match(
match: re.Match[str] | None, node_type: str, confidence: interfaces.Confidence
) -> bool:
return (
match is not None
and match.lastgroup is not None
and match.lastgroup not in EXEMPT_NAME_CATEGORIES
and (node_type != "method" or confidence != interfaces.INFERENCE_FAILURE)
)
class NameChecker(_BasicChecker):
msgs = {
"C0103": (
'%s name "%s" doesn\'t conform to %s',
"invalid-name",
"Used when the name doesn't conform to naming rules "
"associated to its type (constant, variable, class...).",
),
"C0104": (
'Disallowed name "%s"',
"disallowed-name",
"Used when the name matches bad-names or bad-names-rgxs- (unauthorized names).",
{
"old_names": [
("C0102", "blacklisted-name"),
]
},
),
"C0105": (
"Type variable name does not reflect variance%s",
"typevar-name-incorrect-variance",
"Emitted when a TypeVar name doesn't reflect its type variance. "
"According to PEP8, it is recommended to add suffixes '_co' and "
"'_contra' to the variables used to declare covariant or "
"contravariant behaviour respectively. Invariant (default) variables "
"do not require a suffix. The message is also emitted when invariant "
"variables do have a suffix.",
),
"C0131": (
"TypeVar cannot be both covariant and contravariant",
"typevar-double-variance",
'Emitted when both the "covariant" and "contravariant" '
'keyword arguments are set to "True" in a TypeVar.',
),
"C0132": (
'TypeVar name "%s" does not match assigned variable name "%s"',
"typevar-name-mismatch",
"Emitted when a TypeVar is assigned to a variable "
"that does not match its name argument.",
),
}
_options: Options = (
(
"good-names",
{
"default": ("i", "j", "k", "ex", "Run", "_"),
"type": "csv",
"metavar": "<names>",
"help": "Good variable names which should always be accepted,"
" separated by a comma.",
},
),
(
"good-names-rgxs",
{
"default": "",
"type": "regexp_csv",
"metavar": "<names>",
"help": "Good variable names regexes, separated by a comma. If names match any regex,"
" they will always be accepted",
},
),
(
"bad-names",
{
"default": ("foo", "bar", "baz", "toto", "tutu", "tata"),
"type": "csv",
"metavar": "<names>",
"help": "Bad variable names which should always be refused, "
"separated by a comma.",
},
),
(
"bad-names-rgxs",
{
"default": "",
"type": "regexp_csv",
"metavar": "<names>",
"help": "Bad variable names regexes, separated by a comma. If names match any regex,"
" they will always be refused",
},
),
(
"name-group",
{
"default": (),
"type": "csv",
"metavar": "<name1:name2>",
"help": (
"Colon-delimited sets of names that determine each"
" other's naming style when the name regexes"
" allow several styles."
),
},
),
(
"include-naming-hint",
{
"default": False,
"type": "yn",
"metavar": "<y or n>",
"help": "Include a hint for the correct naming format with invalid-name.",
},
),
(
"property-classes",
{
"default": ("abc.abstractproperty",),
"type": "csv",
"metavar": "<decorator names>",
"help": "List of decorators that produce properties, such as "
"abc.abstractproperty. Add to this list to register "
"other decorators that produce valid properties. "
"These decorators are taken in consideration only for invalid-name.",
},
),
)
options: Options = _options + _create_naming_options()
def __init__(self, linter: PyLinter) -> None:
super().__init__(linter)
self._name_group: dict[str, str] = {}
self._bad_names: dict[str, dict[str, list[_BadNamesTuple]]] = {}
self._name_regexps: dict[str, re.Pattern[str]] = {}
self._name_hints: dict[str, str] = {}
self._good_names_rgxs_compiled: list[re.Pattern[str]] = []
self._bad_names_rgxs_compiled: list[re.Pattern[str]] = []
def open(self) -> None:
self.linter.stats.reset_bad_names()
for group in self.linter.config.name_group:
for name_type in group.split(":"):
self._name_group[name_type] = f"group_{group}"
regexps, hints = self._create_naming_rules()
self._name_regexps = regexps
self._name_hints = hints
self._good_names_rgxs_compiled = [
re.compile(rgxp) for rgxp in self.linter.config.good_names_rgxs
]
self._bad_names_rgxs_compiled = [
re.compile(rgxp) for rgxp in self.linter.config.bad_names_rgxs
]
def _create_naming_rules(self) -> tuple[dict[str, Pattern[str]], dict[str, str]]:
regexps: dict[str, Pattern[str]] = {}
hints: dict[str, str] = {}
for name_type in KNOWN_NAME_TYPES:
if name_type in KNOWN_NAME_TYPES_WITH_STYLE:
naming_style_name = getattr(
self.linter.config, f"{name_type}_naming_style"
)
regexps[name_type] = NAMING_STYLES[naming_style_name].get_regex(
name_type
)
else:
naming_style_name = "predefined"
regexps[name_type] = DEFAULT_PATTERNS[name_type]
custom_regex_setting_name = f"{name_type}_rgx"
custom_regex = getattr(self.linter.config, custom_regex_setting_name, None)
if custom_regex is not None:
regexps[name_type] = custom_regex
if custom_regex is not None:
hints[name_type] = f"{custom_regex.pattern!r} pattern"
else:
hints[name_type] = f"{naming_style_name} naming style"
return regexps, hints
@utils.only_required_for_messages("disallowed-name", "invalid-name")
def visit_module(self, node: nodes.Module) -> None:
self._check_name("module", node.name.split(".")[-1], node)
self._bad_names = {}
def leave_module(self, _: nodes.Module) -> None:
for all_groups in self._bad_names.values():
if len(all_groups) < 2:
continue
groups: collections.defaultdict[
int, list[list[_BadNamesTuple]]
] = collections.defaultdict(list)
min_warnings = sys.maxsize
prevalent_group, _ = max(all_groups.items(), key=lambda item: len(item[1]))
for group in all_groups.values():
groups[len(group)].append(group)
min_warnings = min(len(group), min_warnings)
if len(groups[min_warnings]) > 1:
by_line = sorted(
groups[min_warnings],
key=lambda group: min( # type: ignore[no-any-return]
warning[0].lineno
for warning in group
if warning[0].lineno is not None
),
)
warnings: Iterable[_BadNamesTuple] = itertools.chain(*by_line[1:])
else:
warnings = groups[min_warnings][0]
for args in warnings:
self._raise_name_warning(prevalent_group, *args)
@utils.only_required_for_messages("disallowed-name", "invalid-name")
def visit_classdef(self, node: nodes.ClassDef) -> None:
self._check_name("class", node.name, node)
for attr, anodes in node.instance_attrs.items():
if not any(node.instance_attr_ancestors(attr)):
self._check_name("attr", attr, anodes[0])
@utils.only_required_for_messages("disallowed-name", "invalid-name")
def visit_functiondef(self, node: nodes.FunctionDef) -> None:
# Do not emit any warnings if the method is just an implementation
# of a base class method.
confidence = interfaces.HIGH
if node.is_method():
if utils.overrides_a_method(node.parent.frame(future=True), node.name):
return
confidence = (
interfaces.INFERENCE
if utils.has_known_bases(node.parent.frame(future=True))
else interfaces.INFERENCE_FAILURE
)
self._check_name(
_determine_function_name_type(node, config=self.linter.config),
node.name,
node,
confidence,
)
# Check argument names
args = node.args.args
if args is not None:
self._recursive_check_names(args)
visit_asyncfunctiondef = visit_functiondef
@utils.only_required_for_messages(
"disallowed-name",
"invalid-name",
"typevar-name-incorrect-variance",
"typevar-double-variance",
"typevar-name-mismatch",
)
def visit_assignname( # pylint: disable=too-many-branches
self, node: nodes.AssignName
) -> None:
"""Check module level assigned names."""
frame = node.frame(future=True)
assign_type = node.assign_type()
# Check names defined in comprehensions
if isinstance(assign_type, nodes.Comprehension):
self._check_name("inlinevar", node.name, node)
# Check names defined in module scope
elif isinstance(frame, nodes.Module):
# Check names defined in Assign nodes
if isinstance(assign_type, nodes.Assign):
inferred_assign_type = utils.safe_infer(assign_type.value)
# Check TypeVar's and TypeAliases assigned alone or in tuple assignment
if isinstance(node.parent, nodes.Assign):
if self._assigns_typevar(assign_type.value):
self._check_name("typevar", assign_type.targets[0].name, node)
return
if self._assigns_typealias(assign_type.value):
self._check_name("typealias", assign_type.targets[0].name, node)
return
if (
isinstance(node.parent, nodes.Tuple)
and isinstance(assign_type.value, nodes.Tuple)
# protect against unbalanced tuple unpacking
and node.parent.elts.index(node) < len(assign_type.value.elts)
):
assigner = assign_type.value.elts[node.parent.elts.index(node)]
if self._assigns_typevar(assigner):
self._check_name(
"typevar",
assign_type.targets[0]
.elts[node.parent.elts.index(node)]
.name,
node,
)
return
if self._assigns_typealias(assigner):
self._check_name(
"typealias",
assign_type.targets[0]
.elts[node.parent.elts.index(node)]
.name,
node,
)
return
# Check classes (TypeVar's are classes so they need to be excluded first)
elif isinstance(inferred_assign_type, nodes.ClassDef):
self._check_name("class", node.name, node)
# Don't emit if the name redefines an import in an ImportError except handler.
elif not _redefines_import(node) and isinstance(
inferred_assign_type, nodes.Const
):
self._check_name("const", node.name, node)
else:
self._check_name(
"variable", node.name, node, disallowed_check_only=True
)
# Check names defined in AnnAssign nodes
elif isinstance(assign_type, nodes.AnnAssign):
if utils.is_assign_name_annotated_with(node, "Final"):
self._check_name("const", node.name, node)
elif self._assigns_typealias(assign_type.annotation):
self._check_name("typealias", node.name, node)
# Check names defined in function scopes
elif isinstance(frame, nodes.FunctionDef):
# global introduced variable aren't in the function locals
if node.name in frame and node.name not in frame.argnames():
if not _redefines_import(node):
self._check_name("variable", node.name, node)
# Check names defined in class scopes
elif isinstance(frame, nodes.ClassDef):
if not list(frame.local_attr_ancestors(node.name)):
for ancestor in frame.ancestors():
if utils.is_enum(ancestor) or utils.is_assign_name_annotated_with(
node, "Final"
):
self._check_name("class_const", node.name, node)
break
else:
self._check_name("class_attribute", node.name, node)
def _recursive_check_names(self, args: list[nodes.AssignName]) -> None:
"""Check names in a possibly recursive list <arg>."""
for arg in args:
self._check_name("argument", arg.name, arg)
def _find_name_group(self, node_type: str) -> str:
return self._name_group.get(node_type, node_type)
def _raise_name_warning(
self,
prevalent_group: str | None,
node: nodes.NodeNG,
node_type: str,
name: str,
confidence: interfaces.Confidence,
warning: str = "invalid-name",
) -> None:
type_label = constants.HUMAN_READABLE_TYPES[node_type]
hint = self._name_hints[node_type]
if prevalent_group:
# This happens in the multi naming match case. The expected
# prevalent group needs to be spelled out to make the message
# correct.
hint = f"the `{prevalent_group}` group in the {hint}"
if self.linter.config.include_naming_hint:
hint += f" ({self._name_regexps[node_type].pattern!r} pattern)"
args = (
(type_label.capitalize(), name, hint)
if warning == "invalid-name"
else (type_label.capitalize(), name)
)
self.add_message(warning, node=node, args=args, confidence=confidence)
self.linter.stats.increase_bad_name(node_type, 1)
def _name_allowed_by_regex(self, name: str) -> bool:
return name in self.linter.config.good_names or any(
pattern.match(name) for pattern in self._good_names_rgxs_compiled
)
def _name_disallowed_by_regex(self, name: str) -> bool:
return name in self.linter.config.bad_names or any(
pattern.match(name) for pattern in self._bad_names_rgxs_compiled
)
def _check_name(
self,
node_type: str,
name: str,
node: nodes.NodeNG,
confidence: interfaces.Confidence = interfaces.HIGH,
disallowed_check_only: bool = False,
) -> None:
"""Check for a name using the type's regexp."""
def _should_exempt_from_invalid_name(node: nodes.NodeNG) -> bool:
if node_type == "variable":
inferred = utils.safe_infer(node)
if isinstance(inferred, nodes.ClassDef):
return True
return False
if self._name_allowed_by_regex(name=name):
return
if self._name_disallowed_by_regex(name=name):
self.linter.stats.increase_bad_name(node_type, 1)
self.add_message(
"disallowed-name", node=node, args=name, confidence=interfaces.HIGH
)
return
regexp = self._name_regexps[node_type]
match = regexp.match(name)
if _is_multi_naming_match(match, node_type, confidence):
name_group = self._find_name_group(node_type)
bad_name_group = self._bad_names.setdefault(name_group, {})
# Ignored because this is checked by the if statement
warnings = bad_name_group.setdefault(match.lastgroup, []) # type: ignore[union-attr, arg-type]
warnings.append((node, node_type, name, confidence))
if (
match is None
and not disallowed_check_only
and not _should_exempt_from_invalid_name(node)
):
self._raise_name_warning(None, node, node_type, name, confidence)
# Check TypeVar names for variance suffixes
if node_type == "typevar":
self._check_typevar(name, node)
@staticmethod
def _assigns_typevar(node: nodes.NodeNG | None) -> bool:
"""Check if a node is assigning a TypeVar."""
if isinstance(node, astroid.Call):
inferred = utils.safe_infer(node.func)
if (
isinstance(inferred, astroid.ClassDef)
and inferred.qname() in TYPE_VAR_QNAME
):
return True
return False
@staticmethod
def _assigns_typealias(node: nodes.NodeNG | None) -> bool:
"""Check if a node is assigning a TypeAlias."""
inferred = utils.safe_infer(node)
if isinstance(inferred, nodes.ClassDef):
if inferred.qname() == ".Union":
# Union is a special case because it can be used as a type alias
# or as a type annotation. We only want to check the former.
assert node is not None
return not isinstance(node.parent, nodes.AnnAssign)
elif isinstance(inferred, nodes.FunctionDef):
if inferred.qname() == "typing.TypeAlias":
return True
return False
def _check_typevar(self, name: str, node: nodes.AssignName) -> None:
"""Check for TypeVar lint violations."""
if isinstance(node.parent, nodes.Assign):
keywords = node.assign_type().value.keywords
args = node.assign_type().value.args
elif isinstance(node.parent, nodes.Tuple):
keywords = (
node.assign_type().value.elts[node.parent.elts.index(node)].keywords
)
args = node.assign_type().value.elts[node.parent.elts.index(node)].args
variance = TypeVarVariance.invariant
name_arg = None
for kw in keywords:
if variance == TypeVarVariance.double_variant:
pass
elif kw.arg == "covariant" and kw.value.value:
variance = (
TypeVarVariance.covariant
if variance != TypeVarVariance.contravariant
else TypeVarVariance.double_variant
)
elif kw.arg == "contravariant" and kw.value.value:
variance = (
TypeVarVariance.contravariant
if variance != TypeVarVariance.covariant
else TypeVarVariance.double_variant
)
if kw.arg == "name" and isinstance(kw.value, nodes.Const):
name_arg = kw.value.value
if name_arg is None and args and isinstance(args[0], nodes.Const):
name_arg = args[0].value
if variance == TypeVarVariance.double_variant:
self.add_message(
"typevar-double-variance",
node=node,
confidence=interfaces.INFERENCE,
)
self.add_message(
"typevar-name-incorrect-variance",
node=node,
args=("",),
confidence=interfaces.INFERENCE,
)
elif variance == TypeVarVariance.covariant and not name.endswith("_co"):
suggest_name = f"{re.sub('_contra$', '', name)}_co"
self.add_message(
"typevar-name-incorrect-variance",
node=node,
args=(f'. "{name}" is covariant, use "{suggest_name}" instead'),
confidence=interfaces.INFERENCE,
)
elif variance == TypeVarVariance.contravariant and not name.endswith("_contra"):
suggest_name = f"{re.sub('_co$', '', name)}_contra"
self.add_message(
"typevar-name-incorrect-variance",
node=node,
args=(f'. "{name}" is contravariant, use "{suggest_name}" instead'),
confidence=interfaces.INFERENCE,
)
elif variance == TypeVarVariance.invariant and (
name.endswith("_co") or name.endswith("_contra")
):
suggest_name = re.sub("_contra$|_co$", "", name)
self.add_message(
"typevar-name-incorrect-variance",
node=node,
args=(f'. "{name}" is invariant, use "{suggest_name}" instead'),
confidence=interfaces.INFERENCE,
)
if name_arg is not None and name_arg != name:
self.add_message(
"typevar-name-mismatch",
node=node,
args=(name_arg, name),
confidence=interfaces.INFERENCE,
)
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