diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 14f49b01aa9f01..d6e4ed02e9c45f 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -270,6 +270,12 @@ class UnionTests(BaseTestCase):
def test_basics(self):
u = Union[int, float]
self.assertNotEqual(u, Union)
+ with self.assertRaises(TypeError):
+ Union[int, 42]
+ with self.assertRaises(TypeError):
+ Union[int, chr]
+ with self.assertRaises(TypeError):
+ Union[int, ...]
def test_subclass_error(self):
with self.assertRaises(TypeError):
@@ -395,10 +401,6 @@ def test_no_eval_union(self):
def f(x: u): ...
self.assertIs(get_type_hints(f)['x'], u)
- def test_function_repr_union(self):
- def fun() -> int: ...
- self.assertEqual(repr(Union[fun, int]), 'typing.Union[fun, int]')
-
def test_union_str_pattern(self):
# Shouldn't crash; see http://bugs.python.org/issue25390
A = Union[str, Pattern]
@@ -411,11 +413,6 @@ def test_etree(self):
Union[Element, str] # Shouldn't crash
- def Elem(*args):
- return Element(*args)
-
- Union[Elem, str] # Nor should this
-
class TupleTests(BaseTestCase):
@@ -2511,6 +2508,8 @@ class ClassVarTests(BaseTestCase):
def test_basics(self):
with self.assertRaises(TypeError):
ClassVar[1]
+ with self.assertRaises(TypeError):
+ ClassVar[chr]
with self.assertRaises(TypeError):
ClassVar[int, str]
with self.assertRaises(TypeError):
@@ -2551,6 +2550,8 @@ def test_basics(self):
Final[int] # OK
with self.assertRaises(TypeError):
Final[1]
+ with self.assertRaises(TypeError):
+ Final[chr]
with self.assertRaises(TypeError):
Final[int, str]
with self.assertRaises(TypeError):
diff --git a/Lib/typing.py b/Lib/typing.py
index e4e32b5b320d04..1a65f854fb22b6 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -178,11 +178,10 @@ def _type_check(arg, msg, is_argument=True, module=None, *, allow_special_forms=
return arg
if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
raise TypeError(f"Plain {arg} is not valid as type argument")
- if isinstance(arg, (type, TypeVar, ForwardRef, types.UnionType, ParamSpec)):
+ if isinstance(arg, (type, TypeVar, ForwardRef, types.UnionType, ParamSpec,
+ _GenericAlias, _SpecialGenericAlias, NewType)):
return arg
- if not callable(arg):
- raise TypeError(f"{msg} Got {arg!r:.100}.")
- return arg
+ raise TypeError(f"{msg} Got {arg!r:.100}.")
def _is_param_expr(arg):
@@ -2065,6 +2064,50 @@ class Other(Leaf): # Error reported by type checker
return f
+class NewType:
+ """NewType creates simple unique types with almost zero
+ runtime overhead. NewType(name, tp) is considered a subtype of tp
+ by static type checkers. At runtime, NewType(name, tp) returns
+ a dummy callable that simply returns its argument. Usage::
+
+ UserId = NewType('UserId', int)
+
+ def name_by_id(user_id: UserId) -> str:
+ ...
+
+ UserId('user') # Fails type check
+
+ name_by_id(42) # Fails type check
+ name_by_id(UserId(42)) # OK
+
+ num = UserId(5) + 1 # type: int
+ """
+
+ __call__ = _idfunc
+
+ def __init__(self, name, tp):
+ self.__qualname__ = name
+ if '.' in name:
+ name = name.rpartition('.')[-1]
+ self.__name__ = name
+ self.__supertype__ = tp
+ def_mod = _caller()
+ if def_mod != 'typing':
+ self.__module__ = def_mod
+
+ def __repr__(self):
+ return f'{self.__module__}.{self.__qualname__}'
+
+ def __reduce__(self):
+ return self.__qualname__
+
+ def __or__(self, other):
+ return Union[self, other]
+
+ def __ror__(self, other):
+ return Union[other, self]
+
+
# Some unconstrained type variables. These are used by the container types.
# (These are not for export.)
T = TypeVar('T') # Any type.
@@ -2438,50 +2481,6 @@ class body be required.
TypedDict.__mro_entries__ = lambda bases: (_TypedDict,)
-class NewType:
- """NewType creates simple unique types with almost zero
- runtime overhead. NewType(name, tp) is considered a subtype of tp
- by static type checkers. At runtime, NewType(name, tp) returns
- a dummy callable that simply returns its argument. Usage::
-
- UserId = NewType('UserId', int)
-
- def name_by_id(user_id: UserId) -> str:
- ...
-
- UserId('user') # Fails type check
-
- name_by_id(42) # Fails type check
- name_by_id(UserId(42)) # OK
-
- num = UserId(5) + 1 # type: int
- """
-
- __call__ = _idfunc
-
- def __init__(self, name, tp):
- self.__qualname__ = name
- if '.' in name:
- name = name.rpartition('.')[-1]
- self.__name__ = name
- self.__supertype__ = tp
- def_mod = _caller()
- if def_mod != 'typing':
- self.__module__ = def_mod
-
- def __repr__(self):
- return f'{self.__module__}.{self.__qualname__}'
-
- def __reduce__(self):
- return self.__qualname__
-
- def __or__(self, other):
- return Union[self, other]
-
- def __ror__(self, other):
- return Union[other, self]
-
-
# Python-version-specific alias (Python 2: unicode; Python 3: str)
Text = str
diff --git a/Misc/NEWS.d/next/Library/2022-02-06-13-56-58.bpo-46644.rWSd0I.rst b/Misc/NEWS.d/next/Library/2022-02-06-13-56-58.bpo-46644.rWSd0I.rst
new file mode 100644
index 00000000000000..4943e0c94a0a6b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-02-06-13-56-58.bpo-46644.rWSd0I.rst
@@ -0,0 +1,2 @@
+No longer accept arbitrary callables as type arguments in generics. E.g.
+``List[chr]`` is now an error.
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