Add support for pep585 with postponed evaulation

Author: cdce8p

CONTRIBUTORS.txt

@@ -439,3 +439,5 @@ contributors:
 * Logan Miller (komodo472): contributor
 
 * Matthew Suozzo: contributor
+
+* Marc Mueller (cdce8p): contributor

ChangeLog

@@ -31,6 +31,10 @@ Pylint's ChangeLog
 
 * Drop support for Python 3.5
 
+* Add support for pep585 with postponed evaluation
+
+  Closes #3320
+
 What's New in Pylint 2.6.1?
 ===========================
 Release date: TBA

pylint/checkers/typecheck.py

@@ -1732,7 +1732,7 @@ def visit_subscript(self, node):
                 return  # It would be better to handle function
                 # decorators, but let's start slow.
 
-        if not supported_protocol(inferred):
+        if not supported_protocol(inferred, node):
             self.add_message(msg, args=node.value.as_string(), node=node.value)
 
     @check_messages("dict-items-missing-iter")

pylint/checkers/utils.py

@@ -51,7 +51,18 @@
 import re
 import string
 from functools import lru_cache, partial
-from typing import Callable, Dict, Iterable, List, Match, Optional, Set, Tuple, Union
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Iterable,
+    List,
+    Match,
+    Optional,
+    Set,
+    Tuple,
+    Union,
+)
 
 import _string
 import astroid
@@ -215,6 +226,49 @@
 }
 PYMETHODS = set(SPECIAL_METHODS_PARAMS)
 
+SUBSCRIPTABLE_CLASSES_PEP585 = frozenset(
+    (
+        "tuple",
+        "list",
+        "dict",
+        "set",
+        "frozenset",
+        "type",
+        "deque",  # collections
+        "defaultdict",
+        "OrderedDict",
+        "Counter",
+        "ChainMap",
+        "Awaitable",  # collections.abc
+        "Coroutine",
+        "AsyncIterable",
+        "AsyncIterator",
+        "AsyncGenerator",
+        "Iterable",
+        "Iterator",
+        "Generator",
+        "Reversible",
+        "Container",
+        "Collection",
+        "Callable",
+        "Set # typing.AbstractSet",
+        "MutableSet",
+        "Mapping",
+        "MutableMapping",
+        "Sequence",
+        "MutableSequence",
+        "ByteString",
+        "MappingView",
+        "KeysView",
+        "ItemsView",
+        "ValuesView",
+        "AbstractContextManager",  # contextlib
+        "AbstractAsyncContextManager",
+        "Pattern",  # re
+        "Match",
+    )
+)
+
 
 class NoSuchArgumentError(Exception):
     pass
@@ -1107,18 +1161,22 @@ def supports_membership_test(value: astroid.node_classes.NodeNG) -> bool:
     return supported or is_iterable(value)
 
 
-def supports_getitem(value: astroid.node_classes.NodeNG) -> bool:
+def supports_getitem(
+    value: astroid.node_classes.NodeNG, node: astroid.node_classes.NodeNG
+) -> bool:
     if isinstance(value, astroid.ClassDef):
         if _supports_protocol_method(value, CLASS_GETITEM_METHOD):
             return True
+        if is_class_subscriptable_pep585_with_postponed_evaluation_enabled(value, node):
+            return True
     return _supports_protocol(value, _supports_getitem_protocol)
 
 
-def supports_setitem(value: astroid.node_classes.NodeNG) -> bool:
+def supports_setitem(value: astroid.node_classes.NodeNG, *_: Any) -> bool:
     return _supports_protocol(value, _supports_setitem_protocol)
 
 
-def supports_delitem(value: astroid.node_classes.NodeNG) -> bool:
+def supports_delitem(value: astroid.node_classes.NodeNG, *_: Any) -> bool:
     return _supports_protocol(value, _supports_delitem_protocol)
 
 
@@ -1273,6 +1331,27 @@ def is_postponed_evaluation_enabled(node: astroid.node_classes.NodeNG) -> bool:
     return "annotations" in module.future_imports
 
 
+def is_class_subscriptable_pep585_with_postponed_evaluation_enabled(
+    value: astroid.ClassDef, node: astroid.node_classes.NodeNG
+) -> bool:
+    """Check if class is subscriptable with PEP 585 and
+    postponed evaluation enabled.
+    """
+    if not is_postponed_evaluation_enabled(node):
+        return False
+
+    if not isinstance(
+        node.parent, (astroid.AnnAssign, astroid.Arguments, astroid.FunctionDef)
+    ):
+        return False
+    if value.name in SUBSCRIPTABLE_CLASSES_PEP585:
+        return True
+    for name in value.basenames:
+        if name in SUBSCRIPTABLE_CLASSES_PEP585:
+            return True
+    return False
+
+
 def is_subclass_of(child: astroid.ClassDef, parent: astroid.ClassDef) -> bool:
     """
     Check if first node is a subclass of second node.

tests/functional/p/postponed_evaluation_pep585.py

@@ -0,0 +1,86 @@
+"""Test PEP 585 in combination with postponed evaluation PEP 563.
+
+This check requires Python 3.7 or 3.8!
+Testing with 3.8 only, to support TypedDict.
+"""
+# pylint: disable=missing-docstring,unused-argument,unused-import,too-few-public-methods,invalid-name,inherit-non-class
+from __future__ import annotations
+import collections
+import dataclasses
+import typing
+from typing import NamedTuple, TypedDict
+from dataclasses import dataclass
+
+
+AliasInvalid = list[int]  # [unsubscriptable-object]
+
+class CustomIntList(typing.List[int]):
+    pass
+
+class CustomIntListError(list[int]):  # [unsubscriptable-object]
+    pass
+
+cast_variable = [1, 2, 3]
+cast_variable = typing.cast(list[int], cast_variable)  # [unsubscriptable-object]
+
+T = typing.TypeVar("T", list[int], str)  # [unsubscriptable-object]
+
+(lambda x: 2)(list[int])  # [unsubscriptable-object]
+
+
+# Check typing.NamedTuple
+CustomNamedTuple = typing.NamedTuple(
+    "CustomNamedTuple", [("my_var", list[int])])  # [unsubscriptable-object]
+
+class CustomNamedTuple2(NamedTuple):
+    my_var: list[int]
+
+class CustomNamedTuple3(typing.NamedTuple):
+    my_var: list[int]
+
+
+# Check typing.TypedDict
+CustomTypedDict = TypedDict("CustomTypedDict", my_var=list[int])  # [unsubscriptable-object]
+
+CustomTypedDict2 = TypedDict("CustomTypedDict2", {"my_var": list[int]})  # [unsubscriptable-object]
+
+class CustomTypedDict3(TypedDict):
+    my_var: list[int]
+
+class CustomTypedDict4(typing.TypedDict):
+    my_var: list[int]
+
+
+# Check dataclasses
+def my_decorator(*args, **kwargs):
+    def wraps(*args, **kwargs):
+        pass
+    return wraps
+
+@dataclass
+class CustomDataClass:
+    my_var: list[int]
+
+@dataclasses.dataclass
+class CustomDataClass2:
+    my_var: list[int]
+
+@dataclass()
+class CustomDataClass3:
+    my_var: list[int]
+
+@my_decorator
+@dataclasses.dataclass
+class CustomDataClass4:
+    my_var: list[int]
+
+
+# Allowed use cases
+var1: set[int]
+var2: collections.OrderedDict[str, int]
+
+def func(arg: list[int]):
+    pass
+
+def func2() -> list[int]:
+    pass

tests/functional/p/postponed_evaluation_pep585.rc

@@ -0,0 +1,3 @@
+[testoptions]
+min_pyver=3.8
+max_pyver=3.9

tests/functional/p/postponed_evaluation_pep585.txt

@@ -0,0 +1,8 @@
+unsubscriptable-object:15:15::Value 'list' is unsubscriptable
+unsubscriptable-object:20:25:CustomIntListError:Value 'list' is unsubscriptable
+unsubscriptable-object:24:28::Value 'list' is unsubscriptable
+unsubscriptable-object:26:24::Value 'list' is unsubscriptable
+unsubscriptable-object:28:14::Value 'list' is unsubscriptable
+unsubscriptable-object:33:36::Value 'list' is unsubscriptable
+unsubscriptable-object:43:54::Value 'list' is unsubscriptable
+unsubscriptable-object:45:60::Value 'list' is unsubscriptable

tests/functional/p/postponed_evaluation_pep585_error.py

@@ -0,0 +1,85 @@
+"""Test PEP 585 without postponed evaluation. Everything should fail.
+
+This check requires Python 3.7 or Python 3.8!
+Testing with 3.8 only, to support TypedDict.
+"""
+# pylint: disable=missing-docstring,unused-argument,unused-import,too-few-public-methods,invalid-name,inherit-non-class
+import collections
+import dataclasses
+import typing
+from typing import NamedTuple, TypedDict
+from dataclasses import dataclass
+
+
+AliasInvalid = list[int]  # [unsubscriptable-object]
+
+class CustomIntList(typing.List[int]):
+    pass
+
+class CustomIntListError(list[int]):  # [unsubscriptable-object]
+    pass
+
+cast_variable = [1, 2, 3]
+cast_variable = typing.cast(list[int], cast_variable)  # [unsubscriptable-object]
+
+T = typing.TypeVar("T", list[int], str)  # [unsubscriptable-object]
+
+(lambda x: 2)(list[int])  # [unsubscriptable-object]
+
+
+# Check typing.NamedTuple
+CustomNamedTuple = typing.NamedTuple(
+    "CustomNamedTuple", [("my_var", list[int])])  # [unsubscriptable-object]
+
+class CustomNamedTuple2(NamedTuple):
+    my_var: list[int]  # [unsubscriptable-object]
+
+class CustomNamedTuple3(typing.NamedTuple):
+    my_var: list[int]  # [unsubscriptable-object]
+
+
+# Check typing.TypedDict
+CustomTypedDict = TypedDict("CustomTypedDict", my_var=list[int])  # [unsubscriptable-object]
+
+CustomTypedDict2 = TypedDict("CustomTypedDict2", {"my_var": list[int]})  # [unsubscriptable-object]
+
+class CustomTypedDict3(TypedDict):
+    my_var: list[int]  # [unsubscriptable-object]
+
+class CustomTypedDict4(typing.TypedDict):
+    my_var: list[int]  # [unsubscriptable-object]
+
+
+# Check dataclasses
+def my_decorator(*args, **kwargs):
+    def wraps(*args, **kwargs):
+        pass
+    return wraps
+
+@dataclass
+class CustomDataClass:
+    my_var: list[int]  # [unsubscriptable-object]
+
+@dataclasses.dataclass
+class CustomDataClass2:
+    my_var: list[int]  # [unsubscriptable-object]
+
+@dataclass()
+class CustomDataClass3:
+    my_var: list[int]  # [unsubscriptable-object]
+
+@my_decorator
+@dataclasses.dataclass
+class CustomDataClass4:
+    my_var: list[int]  # [unsubscriptable-object]
+
+
+
+var1: set[int]  # [unsubscriptable-object]
+var2: collections.OrderedDict[str, int]  # [unsubscriptable-object]
+
+def func(arg: list[int]):  # [unsubscriptable-object]
+    pass
+
+def func2() -> list[int]:  # [unsubscriptable-object]
+    pass

tests/functional/p/postponed_evaluation_pep585_error.rc

@@ -0,0 +1,3 @@
+[testoptions]
+min_pyver=3.8
+max_pyver=3.9

tests/functional/p/postponed_evaluation_pep585_error.txt

@@ -0,0 +1,20 @@
+unsubscriptable-object:14:15::Value 'list' is unsubscriptable
+unsubscriptable-object:19:25:CustomIntListError:Value 'list' is unsubscriptable
+unsubscriptable-object:23:28::Value 'list' is unsubscriptable
+unsubscriptable-object:25:24::Value 'list' is unsubscriptable
+unsubscriptable-object:27:14::Value 'list' is unsubscriptable
+unsubscriptable-object:32:36::Value 'list' is unsubscriptable
+unsubscriptable-object:35:12:CustomNamedTuple2:Value 'list' is unsubscriptable
+unsubscriptable-object:38:12:CustomNamedTuple3:Value 'list' is unsubscriptable
+unsubscriptable-object:42:54::Value 'list' is unsubscriptable
+unsubscriptable-object:44:60::Value 'list' is unsubscriptable
+unsubscriptable-object:47:12:CustomTypedDict3:Value 'list' is unsubscriptable
+unsubscriptable-object:50:12:CustomTypedDict4:Value 'list' is unsubscriptable
+unsubscriptable-object:61:12:CustomDataClass:Value 'list' is unsubscriptable
+unsubscriptable-object:65:12:CustomDataClass2:Value 'list' is unsubscriptable
+unsubscriptable-object:69:12:CustomDataClass3:Value 'list' is unsubscriptable
+unsubscriptable-object:74:12:CustomDataClass4:Value 'list' is unsubscriptable
+unsubscriptable-object:78:6::Value 'set' is unsubscriptable
+unsubscriptable-object:79:6::Value 'collections.OrderedDict' is unsubscriptable
+unsubscriptable-object:81:14:func:Value 'list' is unsubscriptable
+unsubscriptable-object:84:15:func2:Value 'list' is unsubscriptable