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gh-105144: Runtime-checkable protocols: move all 'sanity checks' to _ProtocolMeta.__subclasscheck__ (#105152)

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Alex Waygood 2023-05-31 18:02:25 +01:00 • committed by GitHub
parent df396b59af
commit c05c31db8c
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3 changed files with 111 additions and 37 deletions
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34
Lib/typing.py
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@ -1727,7 +1727,7 @@ def _caller(depth=1, default='__main__'):
pass
return None
def _allow_reckless_class_checks(depth=3):
def _allow_reckless_class_checks(depth=2):
"""Allow instance and class checks for special stdlib modules.
The abc and functools modules indiscriminately call isinstance() and
@ -1782,14 +1782,22 @@ class _ProtocolMeta(ABCMeta):
)
def __subclasscheck__(cls, other):
if not isinstance(other, type):
# Same error message as for issubclass(1, int).
raise TypeError('issubclass() arg 1 must be a class')
if (
getattr(cls, '_is_protocol', False)
and not cls.__callable_proto_members_only__
and not _allow_reckless_class_checks(depth=2)
and not _allow_reckless_class_checks()
):
raise TypeError(
"Protocols with non-method members don't support issubclass()"
)
if not cls.__callable_proto_members_only__:
raise TypeError(
"Protocols with non-method members don't support issubclass()"
)
if not getattr(cls, '_is_runtime_protocol', False):
raise TypeError(
"Instance and class checks can only be used with "
"@runtime_checkable protocols"
)
return super().__subclasscheck__(other)
def __instancecheck__(cls, instance):
@ -1801,7 +1809,7 @@ class _ProtocolMeta(ABCMeta):
if (
not getattr(cls, '_is_runtime_protocol', False) and
not _allow_reckless_class_checks(depth=2)
not _allow_reckless_class_checks()
):
raise TypeError("Instance and class checks can only be used with"
" @runtime_checkable protocols")
@ -1869,18 +1877,6 @@ class Protocol(Generic, metaclass=_ProtocolMeta):
if not cls.__dict__.get('_is_protocol', False):
return NotImplemented
# First, perform various sanity checks.
if not getattr(cls, '_is_runtime_protocol', False):
if _allow_reckless_class_checks():
return NotImplemented
raise TypeError("Instance and class checks can only be used with"
" @runtime_checkable protocols")
if not isinstance(other, type):
# Same error message as for issubclass(1, int).
raise TypeError('issubclass() arg 1 must be a class')
# Second, perform the actual structural compatibility check.
for attr in cls.__protocol_attrs__:
for base in other.__mro__:
# Check if the members appears in the class dictionary...