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Allow access to class attributes/methods if __new__/__init__ return Never/NoReturn #22279

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a5b0516
if mypy.types.CallableType.instance_type is not None, mark as type
zedzhen Oct 22, 2026
3964117
add tests
zedzhen Oct 22, 2026
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5 changes: 3 additions & 2 deletions mypy/types.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2424,8 +2424,9 @@ def is_kw_arg(self) -> bool:
return ARG_STAR2 in self.arg_kinds

def is_type_obj(self) -> bool:
return self.fallback.type.is_metaclass() and not isinstance(
get_proper_type(self.ret_type), UninhabitedType
return self.fallback.type.is_metaclass() and (
self.instance_type is not None
or not isinstance(get_proper_type(self.ret_type), UninhabitedType)

@hauntsaninja hauntsaninja Oct 23, 2026

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is the or not isinstance(get_proper_type(self.ret_type), UninhabitedType) still needed (after #21441)? can we remove it?

@zedzhen zedzhen Oct 23, 2026

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if remove only or not isinstance(get_proper_type(self.ret_type), UninhabitedType) in pytest-fast failed 11 tests:

FAILED mypy/test/testcheck.py::TypeCheckSuite::check-dataclasses.test::testDataclassDefaultFactoryTypedDict - data: [PROJECT_ROOT]\test-data\unit\check-dataclasses.test:2893:
FAILED mypy/test/testcheck.py::TypeCheckSuite::check-type-object-type-inference.test::testInferTupleType - data: [PROJECT_ROOT]\test-data\unit\check-type-object-type-inference.test:1:
FAILED mypy/test/testdeps.py::GetDependenciesSuite::deps.test::testTypedDict - data: [PROJECT_ROOT]\test-data\unit\deps.test:659:
FAILED mypy/test/testdeps.py::GetDependenciesSuite::deps.test::testTypedDict2 - data: [PROJECT_ROOT]\test-data\unit\deps.test:673:
FAILED mypy/test/testdeps.py::GetDependenciesSuite::deps.test::testTypedDict3 - data: [PROJECT_ROOT]\test-data\unit\deps.test:691:
FAILED mypy/test/testcheck.py::TypeCheckSuite::check-typeddict.test::testTypedDictWithIsInstanceAndIsSubclass - data: [PROJECT_ROOT]\test-data\unit\check-typeddict.test:961:
FAILED mypy/test/testcheck.py::TypeCheckSuite::check-typeddict.test::testGenericTypedDictCreation - data: [PROJECT_ROOT]\test-data\unit\check-typeddict.test:3302:
FAILED mypy/test/testcheck.py::TypeCheckSuite::check-typeddict.test::testTypedDictAttributeOnClassObject - data: [PROJECT_ROOT]\test-data\unit\check-typeddict.test:3414:
FAILED mypy/test/testcheck.py::TypeCheckSuite::check-typeddict.test::testGenericTypedDictCallSyntax - data: [PROJECT_ROOT]\test-data\unit\check-typeddict.test:3465:
FAILED mypy/test/testtypes.py::JoinSuite::test_simple_type_objects - assert False
FAILED mypy/test/testsubtypes.py::SubtypingSuite::test_type_callable_subtyping - AssertionError: def (A) -> B subtype of def (A) -> B

if save only return self.fallback.type.is_metaclass(), tests pass, but get_instance_type may start returning UninhabitedType, and then type_object will fail on assert isinstance(instance_type, Instance) (on types created by plugins that do not set instance_type, but ret_type is UninhabitedType).

)

def get_instance_type(self, *, force_fallback: bool = False) -> ProperType:
Expand Down
182 changes: 182 additions & 0 deletions test-data/unit/check-classes.test
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Original file line number Diff line number Diff line change
Expand Up @@ -8886,6 +8886,188 @@ if object():
reveal_type(D()) # N: Revealed type is "Never"
reveal_type(D(1)) # N: Revealed type is "__main__.D"

[case testNewAndInitNoReturnWithAttributeClassmethodStaticMethod]
from typing import NoReturn, ClassVar, Final

class A:
x: ClassVar[str] = ""
y: Final[int] = 0

def __new__(cls) -> NoReturn: ...

@classmethod
def f(cls) -> "A": ...
@staticmethod
def g() -> "A": ...

class B:
x: ClassVar[str] = ""
y: Final[int] = 0

def __init__(self) -> NoReturn: ...

@classmethod
def f(cls) -> "B": ...
@staticmethod
def g() -> "B": ...

class C:
x: ClassVar[str] = ""
y: Final[int] = 0

def __new__(cls) -> "C": ...
def __init__(self) -> NoReturn: ...

@classmethod
def f(cls) -> "C": ...
@staticmethod
def g() -> "C": ...

class D:
x: ClassVar[str] = ""
y: Final[int] = 0

def __new__(cls) -> NoReturn: ...
def __init__(self) -> NoReturn: ...

@classmethod
def f(cls) -> "D": ...
@staticmethod
def g() -> "D": ...

if object():
reveal_type(A()) # N: Revealed type is "Never"
reveal_type(A.x) # N: Revealed type is "builtins.str"
reveal_type(A.y) # N: Revealed type is "builtins.int"
reveal_type(A.f()) # N: Revealed type is "__main__.A"
reveal_type(A.g()) # N: Revealed type is "__main__.A"

if object():
reveal_type(B()) # N: Revealed type is "Never"
reveal_type(B.x) # N: Revealed type is "builtins.str"
reveal_type(B.y) # N: Revealed type is "builtins.int"
reveal_type(B.f()) # N: Revealed type is "__main__.B"
reveal_type(B.g()) # N: Revealed type is "__main__.B"

if object():
reveal_type(C()) # N: Revealed type is "Never"
reveal_type(C.x) # N: Revealed type is "builtins.str"
reveal_type(C.y) # N: Revealed type is "builtins.int"
reveal_type(C.f()) # N: Revealed type is "__main__.C"
reveal_type(C.g()) # N: Revealed type is "__main__.C"

if object():
reveal_type(D()) # N: Revealed type is "Never"
reveal_type(D.x) # N: Revealed type is "builtins.str"
reveal_type(D.y) # N: Revealed type is "builtins.int"
reveal_type(D.f()) # N: Revealed type is "__main__.D"
reveal_type(D.g()) # N: Revealed type is "__main__.D"

[builtins fixtures/classmethod.pyi]

[case testOverloadedNewAndInitNoReturnWithAttributeClassmethodStaticMethod]
from typing import NoReturn, overload, ClassVar, Final

class A:
x: ClassVar[str] = ""
y: Final[int] = 0

@overload
def __new__(cls) -> NoReturn: ...
@overload
def __new__(cls, a: int) -> "A": ...
def __new__(cls, a: int = ...) -> "A": ...

@classmethod
def f(cls) -> "A": ...
@staticmethod
def g() -> "A": ...

class B:
x: ClassVar[str] = ""
y: Final[int] = 0

@overload
def __init__(self) -> NoReturn: ...
@overload
def __init__(self, a: int) -> None: ...
def __init__(self, a: int = ...) -> None: ...

@classmethod
def f(cls) -> "B": ...
@staticmethod
def g() -> "B": ...

class C:
x: ClassVar[str] = ""
y: Final[int] = 0

def __new__(cls, a: int = ...) -> "C": ...
@overload
def __init__(self) -> NoReturn: ...
@overload
def __init__(self, a: int) -> None: ...
def __init__(self, a: int = ...) -> None: ...

@classmethod
def f(cls) -> "C": ...
@staticmethod
def g() -> "C": ...

class D:
x: ClassVar[str] = ""
y: Final[int] = 0

@overload
def __new__(cls) -> NoReturn: ...
@overload
def __new__(cls, a: int) -> "D": ...
def __new__(cls, a: int = ...) -> "D": ...
@overload
def __init__(self) -> NoReturn: ...
@overload
def __init__(self, a: int) -> None: ...
def __init__(self, a: int = ...) -> None: ...

@classmethod
def f(cls) -> "D": ...
@staticmethod
def g() -> "D": ...

if object():
reveal_type(A()) # N: Revealed type is "Never"
reveal_type(A(1)) # N: Revealed type is "__main__.A"
reveal_type(A.x) # N: Revealed type is "builtins.str"
reveal_type(A.y) # N: Revealed type is "builtins.int"
reveal_type(A.f()) # N: Revealed type is "__main__.A"
reveal_type(A.g()) # N: Revealed type is "__main__.A"

if object():
reveal_type(B()) # N: Revealed type is "Never"
reveal_type(B(1)) # N: Revealed type is "__main__.B"
reveal_type(B.x) # N: Revealed type is "builtins.str"
reveal_type(B.y) # N: Revealed type is "builtins.int"
reveal_type(B.f()) # N: Revealed type is "__main__.B"
reveal_type(B.g()) # N: Revealed type is "__main__.B"

if object():
reveal_type(C()) # N: Revealed type is "Never"
reveal_type(C(1)) # N: Revealed type is "__main__.C"
reveal_type(C.x) # N: Revealed type is "builtins.str"
reveal_type(C.y) # N: Revealed type is "builtins.int"
reveal_type(C.f()) # N: Revealed type is "__main__.C"
reveal_type(C.g()) # N: Revealed type is "__main__.C"

if object():
reveal_type(D()) # N: Revealed type is "Never"
reveal_type(D(1)) # N: Revealed type is "__main__.D"
reveal_type(D.x) # N: Revealed type is "builtins.str"
reveal_type(D.y) # N: Revealed type is "builtins.int"
reveal_type(D.f()) # N: Revealed type is "__main__.D"
reveal_type(D.g()) # N: Revealed type is "__main__.D"

[builtins fixtures/classmethod.pyi]

[case testClassScopeImportWithWrapperAndError]
class Foo:
from mod import foo # E: Unsupported class scoped import
Expand Down
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