10000 gh-104555: Runtime-checkable protocols: Don't let previous calls to `isinstance()` influence whether `issubclass()` raises an exception by AlexWaygood · Pull Request #104559 · python/cpython · GitHub
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gh-104555: Runtime-checkable protocols: Don't let previous calls to isinstance() influence whether issubclass() raises an exception #104559

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Merged
merged 12 commits into from
May 17, 2023
Merged

gh-104555: Runtime-checkable protocols: Don't let previous calls to isinstance() influence whether issubclass() raises an exception #104559

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2601138
gh-104555: Sidestep the ABCMeta.__instancecheck__ cache in typing._Pr…
AlexWaygood May 16, 2023
f3a4551
Simplify test
AlexWaygood May 16, 2023
714badc
Optimise
AlexWaygood May 16, 2023
04ed974
who needs codespell when we have carl
AlexWaygood May 16, 2023
9c5c75f
Merge branch 'fix-runtime-protocols' of https://github.com/AlexWaygoo…
AlexWaygood May 16, 2023
49373a9
be more careful
AlexWaygood May 16, 2023
e114fe9
Add comment
AlexWaygood May 16, 2023
b5cc9cd
Add more failing tests (thanks sunmy2019!)
AlexWaygood May 17, 2023
5f72b82
Better fix
AlexWaygood May 17, 2023
bb56e13
Improve comments
AlexWaygood May 17, 2023
430cacd
📜🤖 Added by blurb_it.
blurb-it[bot] May 17, 2023
f9273fc
Apply suggestions from code review
AlexWaygood May 17, 2023
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@AlexWaygood
AlexWaygood committed May 17, 2023
commit bb56e1318a56a41ea21e21aec179e751cad0197f
36 changes: 20 additions & 16 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2663,12 +2663,13 @@ class Eggs:
def __init__(self) -> None:
self.x = 42

# gh-104555: ABCMeta might cache the result of this isinstance check
# if we called super().__instancecheck__ in the wrong place
# in _ProtocolMeta.__instancecheck__...
self.assertIsInstance(Eggs(), Spam)

# ...and if it did, then TypeError wouldn't be raised here!
# gh-104555: If we didn't override ABCMeta.__subclasscheck__ in _ProtocolMeta,
# TypeError wouldn't be raised here,
# as the cached result of the isinstance() check immediately above
# would mean the issubclass() call would short-circuit
# before we got to the "raise TypeError" line
with self.assertRaises(TypeError):
issubclass(Eggs, Spam)

Expand All @@ -2679,12 +2680,13 @@ class Spam(Protocol):

class Eggs: ...

# gh-104555: ABCMeta might cache the result of this isinstance check
# if we called super().__instancecheck__ in the wrong place
# in _ProtocolMeta.__instancecheck__...
self.assertNotIsInstance(Eggs(), Spam)

# ...and if it did, then TypeError wouldn't be raised here!
# gh-104555: If we didn't override ABCMeta.__subclasscheck__ in _ProtocolMeta,
# TypeError wouldn't be raised here,
# as the cached result of the isinstance() check immediately above
# would mean the issubclass() call would short-circuit
# before we got to the "raise TypeError" line
with self.assertRaises(TypeError):
issubclass(Eggs, Spam)

Expand All @@ -2699,12 +2701,13 @@ def __getattr__(self, attr):
return 42
raise AttributeError(attr)

# gh-104555: ABCMeta might cache the result of this isinstance check
# if we called super().__instancecheck__ in the wrong place
# in _ProtocolMeta.__instancecheck__...
self.assertNotIsInstance(Eggs(), Spam)

# ...and if it did, then TypeError wouldn't be raised here!
# gh-104555: If we didn't override ABCMeta.__subclasscheck__ in _ProtocolMeta,
# TypeError wouldn't be raised here,
# as the cached result of the isinstance() check immediately above
# would mean the issubclass() call would short-circuit
# before we got to the "raise TypeError" line
with self.assertRaises(TypeError):
issubclass(Eggs, Spam)

Expand All @@ -2717,12 +2720,13 @@ class Eggs[T]:
def __init__(self, x: T) -> None:
self.x = x

# gh-104555: ABCMeta might cache the result of this isinstance check
# if we called super().__instancecheck__ in the wrong place
# in _ProtocolMeta.__instancecheck__...
self.assertIsInstance(Eggs(42), Spam)

# ...and if it did, then TypeError wouldn't be raised here!
# gh-104555: If we didn't override ABCMeta.__subclasscheck__ in _ProtocolMeta,
# TypeError wouldn't be raised here,
# as the cached result of the isinstance() check immediately above
# would mean the issubclass() call would short-circuit
# before we got to the "raise TypeError" line
with self.assertRaises(TypeError):
issubclass(Eggs, Spam)

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0