From c0c0dfa19444eca81f062aa8ffb6ad0bbeeaab6c Mon Sep 17 00:00:00 2001 From: Gregory Beauregard Date: Wed, 26 Jan 2022 19:11:51 -0800 Subject: [PATCH] bpo-46539: Pass status of special typeforms to forward references (GH-30926) Previously this didn't matter because there weren't any valid code paths that could trigger a type check with a special form, but after the bug fix for `Annotated` wrapping special forms it's now possible to annotate something like `Annotated['ClassVar[int]', (3, 4)]`. This change would also be needed for proposed future changes, such as allowing `ClassVar` and `Final` to nest each other in dataclasses. (cherry picked from commit ced50051bb752a7c1e616f4b0c001f37f0354f32) Co-authored-by: Gregory Beauregard --- Lib/test/test_typing.py | 14 ++++++++++++++ Lib/typing.py | 6 +++--- .../2022-01-26-20-36-30.bpo-46539.23iW1d.rst | 1 + 3 files changed, 18 insertions(+), 3 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2022-01-26-20-36-30.bpo-46539.23iW1d.rst diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py index f70311c95b24e4..dfca96b9099322 100644 --- a/Lib/test/test_typing.py +++ b/Lib/test/test_typing.py @@ -2623,6 +2623,20 @@ def foo(a: 'Callable[..., T]'): self.assertEqual(get_type_hints(foo, globals(), locals()), {'a': Callable[..., T]}) + def test_special_forms_forward(self): + + class C: + a: Annotated['ClassVar[int]', (3, 5)] = 4 + b: Annotated['Final[int]', "const"] = 4 + + class CF: + b: List['Final[int]'] = 4 + + self.assertEqual(get_type_hints(C, globals())['a'], ClassVar[int]) + self.assertEqual(get_type_hints(C, globals())['b'], Final[int]) + with self.assertRaises(TypeError): + get_type_hints(CF, globals()), + def test_syntax_error(self): with self.assertRaises(SyntaxError): diff --git a/Lib/typing.py b/Lib/typing.py index fdc0f163d65043..18b21e96435b32 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -125,12 +125,12 @@ # legitimate imports of those modules. -def _type_convert(arg, module=None): +def _type_convert(arg, module=None, *, allow_special_forms=False): """For converting None to type(None), and strings to ForwardRef.""" if arg is None: return type(None) if isinstance(arg, str): - return ForwardRef(arg, module=module) + return ForwardRef(arg, module=module, is_class=allow_special_forms) return arg @@ -152,7 +152,7 @@ def _type_check(arg, msg, is_argument=True, module=None, *, allow_special_forms= if is_argument: invalid_generic_forms += (Final,) - arg = _type_convert(arg, module=module) + arg = _type_convert(arg, module=module, allow_special_forms=allow_special_forms) if (isinstance(arg, _GenericAlias) and arg.__origin__ in invalid_generic_forms): raise TypeError(f"{arg} is not valid as type argument") diff --git a/Misc/NEWS.d/next/Library/2022-01-26-20-36-30.bpo-46539.23iW1d.rst b/Misc/NEWS.d/next/Library/2022-01-26-20-36-30.bpo-46539.23iW1d.rst new file mode 100644 index 00000000000000..2bdde21b6e58e5 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-01-26-20-36-30.bpo-46539.23iW1d.rst @@ -0,0 +1 @@ +In :func:`typing.get_type_hints`, support evaluating stringified ``ClassVar`` and ``Final`` annotations inside ``Annotated``. Patch by Gregory Beauregard. pFad - Phonifier reborn

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