[Python-checkins] bpo-45166: fixes `get_type_hints` failure on `Final` (GH-28279) (GH-28560)
ambv
webhook-mailer at python.org
Sat Sep 25 05:21:18 EDT 2021
https://github.com/python/cpython/commit/d312b8516e11027ce97897d39764e242f0f57087
commit: d312b8516e11027ce97897d39764e242f0f57087
branch: 3.10
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: ambv <lukasz at langa.pl>
date: 2021-09-25T11:21:13+02:00
summary:
bpo-45166: fixes `get_type_hints` failure on `Final` (GH-28279) (GH-28560)
Co-authored-by: Łukasz Langa <lukasz at langa.pl>
Co-authored-by: Ken Jin <28750310+Fidget-Spinner at users.noreply.github.com>
(cherry picked from commit 784905dbeff68cf788bbeefe0a675af1af04affc)
Co-authored-by: Nikita Sobolev <mail at sobolevn.me>
files:
A Lib/test/ann_module5.py
A Lib/test/ann_module6.py
A Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst
M Lib/test/test_typing.py
M Lib/typing.py
diff --git a/Lib/test/ann_module5.py b/Lib/test/ann_module5.py
new file mode 100644
index 0000000000000..837041e121f65
--- /dev/null
+++ b/Lib/test/ann_module5.py
@@ -0,0 +1,10 @@
+# Used by test_typing to verify that Final wrapped in ForwardRef works.
+
+from __future__ import annotations
+
+from typing import Final
+
+name: Final[str] = "final"
+
+class MyClass:
+ value: Final = 3000
diff --git a/Lib/test/ann_module6.py b/Lib/test/ann_module6.py
new file mode 100644
index 0000000000000..679175669bc3a
--- /dev/null
+++ b/Lib/test/ann_module6.py
@@ -0,0 +1,7 @@
+# Tests that top-level ClassVar is not allowed
+
+from __future__ import annotations
+
+from typing import ClassVar
+
+wrong: ClassVar[int] = 1
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index c84ff0f0a24ac..4f250f2e108cc 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -2969,7 +2969,7 @@ async def __aexit__(self, etype, eval, tb):
# Definitions needed for features introduced in Python 3.6
-from test import ann_module, ann_module2, ann_module3
+from test import ann_module, ann_module2, ann_module3, ann_module5, ann_module6
from typing import AsyncContextManager
class A:
@@ -3333,6 +3333,22 @@ class C(Generic[T]): pass
(Concatenate[int, P], int))
self.assertEqual(get_args(list | str), (list, str))
+ def test_forward_ref_and_final(self):
+ # https://bugs.python.org/issue45166
+ hints = get_type_hints(ann_module5)
+ self.assertEqual(hints, {'name': Final[str]})
+
+ hints = get_type_hints(ann_module5.MyClass)
+ self.assertEqual(hints, {'value': Final})
+
+ def test_top_level_class_var(self):
+ # https://bugs.python.org/issue45166
+ with self.assertRaisesRegex(
+ TypeError,
+ r'typing.ClassVar\[int\] is not valid as type argument',
+ ):
+ get_type_hints(ann_module6)
+
class CollectionsAbcTests(BaseTestCase):
diff --git a/Lib/typing.py b/Lib/typing.py
index 5873d536a9ec4..85908304270c0 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -143,7 +143,7 @@ def _type_convert(arg, module=None):
return arg
-def _type_check(arg, msg, is_argument=True, module=None):
+def _type_check(arg, msg, is_argument=True, module=None, *, is_class=False):
"""Check that the argument is a type, and return it (internal helper).
As a special case, accept None and return type(None) instead. Also wrap strings
@@ -156,14 +156,16 @@ def _type_check(arg, msg, is_argument=True, module=None):
We append the repr() of the actual value (truncated to 100 chars).
"""
invalid_generic_forms = (Generic, Protocol)
- if is_argument:
- invalid_generic_forms = invalid_generic_forms + (ClassVar, Final)
+ if not is_class:
+ invalid_generic_forms += (ClassVar,)
+ if is_argument:
+ invalid_generic_forms += (Final,)
arg = _type_convert(arg, module=module)
if (isinstance(arg, _GenericAlias) and
arg.__origin__ in invalid_generic_forms):
raise TypeError(f"{arg} is not valid as type argument")
- if arg in (Any, NoReturn):
+ if arg in (Any, NoReturn, Final):
return arg
if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
raise TypeError(f"Plain {arg} is not valid as type argument")
@@ -654,9 +656,10 @@ class ForwardRef(_Final, _root=True):
__slots__ = ('__forward_arg__', '__forward_code__',
'__forward_evaluated__', '__forward_value__',
- '__forward_is_argument__', '__forward_module__')
+ '__forward_is_argument__', '__forward_is_class__',
+ '__forward_module__')
- def __init__(self, arg, is_argument=True, module=None):
+ def __init__(self, arg, is_argument=True, module=None, *, is_class=False):
if not isinstance(arg, str):
raise TypeError(f"Forward reference must be a string -- got {arg!r}")
try:
@@ -668,6 +671,7 @@ def __init__(self, arg, is_argument=True, module=None):
self.__forward_evaluated__ = False
self.__forward_value__ = None
self.__forward_is_argument__ = is_argument
+ self.__forward_is_class__ = is_class
self.__forward_module__ = module
def _evaluate(self, globalns, localns, recursive_guard):
@@ -684,10 +688,11 @@ def _evaluate(self, globalns, localns, recursive_guard):
globalns = getattr(
sys.modules.get(self.__forward_module__, None), '__dict__', globalns
)
- type_ =_type_check(
+ type_ = _type_check(
eval(self.__forward_code__, globalns, localns),
"Forward references must evaluate to types.",
is_argument=self.__forward_is_argument__,
+ is_class=self.__forward_is_class__,
)
self.__forward_value__ = _eval_type(
type_, globalns, localns, recursive_guard | {self.__forward_arg__}
@@ -1800,7 +1805,7 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False):
if value is None:
value = type(None)
if isinstance(value, str):
- value = ForwardRef(value, is_argument=False)
+ value = ForwardRef(value, is_argument=False, is_class=True)
value = _eval_type(value, base_globals, base_locals)
hints[name] = value
return hints if include_extras else {k: _strip_annotations(t) for k, t in hints.items()}
@@ -1832,7 +1837,13 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False):
if value is None:
value = type(None)
if isinstance(value, str):
- value = ForwardRef(value)
+ # class-level forward refs were handled above, this must be either
+ # a module-level annotation or a function argument annotation
+ value = ForwardRef(
+ value,
+ is_argument=not isinstance(obj, types.ModuleType),
+ is_class=False,
+ )
value = _eval_type(value, globalns, localns)
if name in defaults and defaults[name] is None:
value = Optional[value]
diff --git a/Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst b/Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst
new file mode 100644
index 0000000000000..b7242d45ea9be
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-09-10-21-35-53.bpo-45166.UHipXF.rst
@@ -0,0 +1,2 @@
+:func:`typing.get_type_hints` now works with :data:`~typing.Final` wrapped in
+:class:`~typing.ForwardRef`.
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