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bpo-45166: fixes get_type_hints failure on Final (GH-28279) (GH-28560)

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Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
(cherry picked from commit 784905dbef)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
This commit is contained in:
Miss Islington (bot) 2021-09-25 02:21:13 -07:00 • committed by GitHub
parent 371ca3b54d
commit d312b8516e
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 56 additions and 10 deletions
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29
Lib/typing.py
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@ -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 @@ class ForwardRef(_Final, _root=True):
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 @@ class ForwardRef(_Final, _root=True):
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]