[Python-checkins] gh-92261: Disallow iteration of Union (and other special forms) (GH-92262) (GH-92582)
serhiy-storchaka
webhook-mailer at python.org
Tue May 10 01:39:39 EDT 2022
https://github.com/python/cpython/commit/7540a432cedf478d03da1254c470ac552f397916
commit: 7540a432cedf478d03da1254c470ac552f397916
branch: 3.11
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: serhiy-storchaka <storchaka at gmail.com>
date: 2022-05-10T08:39:31+03:00
summary:
gh-92261: Disallow iteration of Union (and other special forms) (GH-92262) (GH-92582)
(cherry picked from commit 4739997e141c4c84bd2241d4d887c3c658d92700)
Co-authored-by: Matthew Rahtz <matthew.rahtz at gmail.com>
files:
A Misc/NEWS.d/next/Core and Builtins/2022-05-03-20-12-18.gh-issue-92261.aigLnb.rst
M Lib/test/test_genericalias.py
M Lib/test/test_typing.py
M Lib/typing.py
diff --git a/Lib/test/test_genericalias.py b/Lib/test/test_genericalias.py
index 5fba74ec864f1..6959c2ae3c80e 100644
--- a/Lib/test/test_genericalias.py
+++ b/Lib/test/test_genericalias.py
@@ -487,5 +487,25 @@ def test_del_iter(self):
del iter_x
+class TypeIterationTests(unittest.TestCase):
+ _UNITERABLE_TYPES = (list, tuple)
+
+ def test_cannot_iterate(self):
+ for test_type in self._UNITERABLE_TYPES:
+ with self.subTest(type=test_type):
+ expected_error_regex = "object is not iterable"
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ iter(test_type)
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ list(test_type)
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ for _ in test_type:
+ pass
+
+ def test_is_not_instance_of_iterable(self):
+ for type_to_test in self._UNITERABLE_TYPES:
+ self.assertNotIsInstance(type_to_test, Iterable)
+
+
if __name__ == "__main__":
unittest.main()
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 8399465f6052d..6e1e8d6e1b473 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -7348,6 +7348,37 @@ def test_all_exported_names(self):
self.assertSetEqual(computed_all, actual_all)
+class TypeIterationTests(BaseTestCase):
+ _UNITERABLE_TYPES = (
+ Any,
+ Union,
+ Union[str, int],
+ Union[str, T],
+ List,
+ Tuple,
+ Callable,
+ Callable[..., T],
+ Callable[[T], str],
+ Annotated,
+ Annotated[T, ''],
+ )
+
+ def test_cannot_iterate(self):
+ expected_error_regex = "object is not iterable"
+ for test_type in self._UNITERABLE_TYPES:
+ with self.subTest(type=test_type):
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ iter(test_type)
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ list(test_type)
+ with self.assertRaisesRegex(TypeError, expected_error_regex):
+ for _ in test_type:
+ pass
+
+ def test_is_not_instance_of_iterable(self):
+ for type_to_test in self._UNITERABLE_TYPES:
+ self.assertNotIsInstance(type_to_test, collections.abc.Iterable)
+
if __name__ == '__main__':
main()
diff --git a/Lib/typing.py b/Lib/typing.py
index bdc14e39033dc..46ef2d9cf6005 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -405,9 +405,24 @@ def __deepcopy__(self, memo):
return self
+class _NotIterable:
+ """Mixin to prevent iteration, without being compatible with Iterable.
+
+ That is, we could do:
+ def __iter__(self): raise TypeError()
+ But this would make users of this mixin duck type-compatible with
+ collections.abc.Iterable - isinstance(foo, Iterable) would be True.
+
+ Luckily, we can instead prevent iteration by setting __iter__ to None, which
+ is treated specially.
+ """
+
+ __iter__ = None
+
+
# Internal indicator of special typing constructs.
# See __doc__ instance attribute for specific docs.
-class _SpecialForm(_Final, _root=True):
+class _SpecialForm(_Final, _NotIterable, _root=True):
__slots__ = ('_name', '__doc__', '_getitem')
def __init__(self, getitem):
@@ -1498,7 +1513,7 @@ def __iter__(self):
# 1 for List and 2 for Dict. It may be -1 if variable number of
# parameters are accepted (needs custom __getitem__).
-class _SpecialGenericAlias(_BaseGenericAlias, _root=True):
+class _SpecialGenericAlias(_NotIterable, _BaseGenericAlias, _root=True):
def __init__(self, origin, nparams, *, inst=True, name=None):
if name is None:
name = origin.__name__
@@ -1541,7 +1556,7 @@ def __or__(self, right):
def __ror__(self, left):
return Union[left, self]
-class _CallableGenericAlias(_GenericAlias, _root=True):
+class _CallableGenericAlias(_NotIterable, _GenericAlias, _root=True):
def __repr__(self):
assert self._name == 'Callable'
args = self.__args__
@@ -1606,7 +1621,7 @@ def __getitem__(self, params):
return self.copy_with(params)
-class _UnionGenericAlias(_GenericAlias, _root=True):
+class _UnionGenericAlias(_NotIterable, _GenericAlias, _root=True):
def copy_with(self, params):
return Union[params]
@@ -2046,7 +2061,7 @@ def _proto_hook(other):
cls.__init__ = _no_init_or_replace_init
-class _AnnotatedAlias(_GenericAlias, _root=True):
+class _AnnotatedAlias(_NotIterable, _GenericAlias, _root=True):
"""Runtime representation of an annotated type.
At its core 'Annotated[t, dec1, dec2, ...]' is an alias for the type 't'
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-05-03-20-12-18.gh-issue-92261.aigLnb.rst b/Misc/NEWS.d/next/Core and Builtins/2022-05-03-20-12-18.gh-issue-92261.aigLnb.rst
new file mode 100644
index 0000000000000..df0228e273d8e
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-05-03-20-12-18.gh-issue-92261.aigLnb.rst
@@ -0,0 +1 @@
+Fix hang when trying to iterate over a ``typing.Union``.
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