test-data/unit/check-generic-subtyping.test

-- Test cases for the type checker related to subtyping and inheritance with
-- generics.


-- Subtyping + inheritance
-- -----------------------


[case testSubtypingAndInheritingNonGenericTypeFromGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
ac: A[C]
ad: A[D]
b: B

if int():
    b = ad # E: Incompatible types in assignment (expression has type "A[D]", variable has type "B")
    ad = b # E: Incompatible types in assignment (expression has type "B", variable has type "A[D]")
if int():
    b = ac # E: Incompatible types in assignment (expression has type "A[C]", variable has type "B")

if int():
    b = b
    ac = b

class C: pass
class A(Generic[T]): pass
class B(A[C]): pass
class D: pass

[case testSubtypingAndInheritingGenericTypeFromNonGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
a: A
bc: B[C]
bd: B[D]

if int():
    bc = bd # E: Incompatible types in assignment (expression has type "B[D]", variable has type "B[C]")
    bd = bc # E: Incompatible types in assignment (expression has type "B[C]", variable has type "B[D]")
if int():
    bc = a  # E: Incompatible types in assignment (expression has type "A", variable has type "B[C]")
    bd = a  # E: Incompatible types in assignment (expression has type "A", variable has type "B[D]")

if int():
    a = bc
if int():
    a = bd

class A: pass
class B(A, Generic[T]): pass
class C: pass
class D: pass

[case testSubtypingAndInheritingGenericTypeFromGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
ac: A[C]
ad: A[D]
bcc: B[C, C]
bdc: B[D, C]

if int():
    ad = bcc # E: Incompatible types in assignment (expression has type "B[C, C]", variable has type "A[D]")
if int():
    ad = bdc # E: Incompatible types in assignment (expression has type "B[D, C]", variable has type "A[D]")
    bcc = ac # E: Incompatible types in assignment (expression has type "A[C]", variable has type "B[C, C]")
    bdc = ac # E: Incompatible types in assignment (expression has type "A[C]", variable has type "B[D, C]")

if int():
    bcc = bcc
    bdc = bdc
    ac = bcc
if int():
    ac = bdc

class A(Generic[T]): pass
class B(A[S], Generic[T, S]): pass
class C: pass
class D: pass

[case testSubtypingAndInheritingGenericTypeFromGenericTypeAcrossHierarchy]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
X = TypeVar('X')
Y = TypeVar('Y')
ae: A[A[E]]
af: A[A[F]]

cef: C[E, F]
cff: C[F, F]
cfe: C[F, E]

if int():
    ae = cef # E: Incompatible types in assignment (expression has type "C[E, F]", variable has type "A[A[E]]")
    af = cfe # E: Incompatible types in assignment (expression has type "C[F, E]", variable has type "A[A[F]]")

if int():
    ae = cfe
    af = cef
if int():
    af = cff

class A(Generic[T]): pass
class B(A[S], Generic[T, S]): pass
class C(B[A[X], A[Y]], Generic[X, Y]): pass
class E: pass
class F: pass

[case testIncludingBaseClassTwice]
from typing import TypeVar, Generic
t = TypeVar('t')
class I(Generic[t]): pass
class A(I[C], I[object]): pass # E: Duplicate base class "I"
class C: pass


-- Accessing inherited generic members
-- -----------------------------------


[case testAccessingMethodInheritedFromGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
b: B[C, D]
c: C
d: D

b.f(c) # E: Argument 1 to "f" of "A" has incompatible type "C"; expected "D"
b.f(d)

class A(Generic[T]):
    def f(self, a: T) -> None:
        pass
class B(A[S], Generic[T, S]): pass
class C: pass
class D: pass
[builtins fixtures/tuple.pyi]

[case testAccessingMethodInheritedFromGenericTypeInNonGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
b: B
c: C
d: D

b.f(c) # E: Argument 1 to "f" of "A" has incompatible type "C"; expected "D"
b.f(d)

class C: pass
class D: pass
class A(Generic[T]):
    def f(self, a: T) -> None:
        pass
class B(A[D]): pass
[builtins fixtures/tuple.pyi]

[case testAccessingMemberVarInheritedFromGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
class A(Generic[T]):
    def __init__(self, a: T) -> None:
        self.a = a

b: B[C, D]
c: C
d: D

b.a = c # E: Incompatible types in assignment (expression has type "C", variable has type "D")
b.a = d

class B(A[S], Generic[T, S]): pass
class C: pass
class D: pass
[builtins fixtures/tuple.pyi]


-- Overriding with generic types
-- -----------------------------


[case testOverridingMethodInSimpleTypeInheritingGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
class B(Generic[T]):
    def f(self, a: T) -> None: pass
    def g(self, a: T) -> None: pass
class C: pass
class D: pass
class A(B[C]):
    def f(self, a: D) -> None: pass \
        # E: Argument 1 of "f" is incompatible with supertype "B"; supertype defines the argument type as "C" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def g(self, a: C) -> None: pass
[out]

[case testOverridingMethodInGenericTypeInheritingSimpleType]
from typing import TypeVar, Generic
T = TypeVar('T')
class C: pass
class B:
    def f(self, a: C) -> None: pass
    def g(self, a: C) -> None: pass
class A(B, Generic[T]):
    def f(self, a: T) -> None: pass \
        # E: Argument 1 of "f" is incompatible with supertype "B"; supertype defines the argument type as "C" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def g(self, a: 'C') -> None: pass
[out]

[case testOverridingMethodInGenericTypeInheritingGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
class B(Generic[T]):
    def f(self, a: T) -> None: pass
    def g(self, a: T) -> None: pass
class A(B[S], Generic[T, S]):
    def f(self, a: T) -> None: pass \
        # E: Argument 1 of "f" is incompatible with supertype "B"; supertype defines the argument type as "S" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def g(self, a: S) -> None: pass
[out]

[case testOverridingMethodInMultilevelHierarchyOfGenericTypes]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
U = TypeVar('U')
V = TypeVar('V')

class D: pass
class C(Generic[T, U, V]):
    def f(self, a: V) -> None: pass
    def g(self, a: V) -> None: pass
class B(C[D, D, T], Generic[T]): pass
class A(B[S], Generic[T, S]):
    def f(self, a: T) -> None: pass \
        # E: Argument 1 of "f" is incompatible with supertype "C"; supertype defines the argument type as "S" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def g(self, a: S) -> None: pass
[out]

[case testOverrideGenericMethodInNonGenericClass]
from typing import TypeVar

T = TypeVar('T')
S = TypeVar('S')

class A:
    def f(self, x: T, y: S) -> None: pass
class B(A):
    def f(self, x: S, y: T) -> None: pass
class C(A):
    # Okay, because T = object allows any type for the arguments.
    def f(self, x: T, y: T) -> None: pass

[case testOverrideGenericMethodInNonGenericClassLists]
from typing import TypeVar, List

T = TypeVar('T')
S = TypeVar('S')

class A:
    def f(self, x: List[T], y: List[S]) -> None: pass
class B(A):
    def f(self, x: List[S], y: List[T]) -> None: pass
class C(A):
    def f(self, x: List[T], y: List[T]) -> None: pass  # Fail
[builtins fixtures/list.pyi]
[out]
main:11: error: Signature of "f" incompatible with supertype "A"
main:11: note:      Superclass:
main:11: note:          def [T, S] f(self, x: list[T], y: list[S]) -> None
main:11: note:      Subclass:
main:11: note:          def [T] f(self, x: list[T], y: list[T]) -> None

[case testOverrideGenericMethodInNonGenericClassGeneralize]
from typing import TypeVar

T = TypeVar('T')
T1 = TypeVar('T1', bound=str)
S = TypeVar('S')

class A:
    def f(self, x: int, y: S) -> None: pass
class B(A):
    def f(self, x: T, y: S) -> None: pass
class C(A):
    def f(self, x: T, y: str) -> None: pass
class D(A):
    def f(self, x: T1, y: S) -> None: pass # TODO: This error could be more specific.
[out]
main:12: error: Argument 2 of "f" is incompatible with supertype "A"; supertype defines the argument type as "S"
main:12: note: This violates the Liskov substitution principle
main:12: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
main:14: error: Signature of "f" incompatible with supertype "A"
main:14: note:      Superclass:
main:14: note:          def [S] f(self, x: int, y: S) -> None
main:14: note:      Subclass:
main:14: note:          def [T1: str, S] f(self, x: T1, y: S) -> None

-- Inheritance from generic types with implicit dynamic supertype
-- --------------------------------------------------------------


[case testInheritanceFromGenericWithImplicitDynamicAndSubtyping]
from typing import TypeVar, Generic
T = TypeVar('T')
a: A
bc: B[C]
bd: B[D]

if int():
    a = bc # E: Incompatible types in assignment (expression has type "B[C]", variable has type "A")
    bc = a
    bd = a

class B(Generic[T]): pass
class A(B): pass
class C: pass
class D: pass
[out]

[case testInheritanceFromGenericWithImplicitDynamicAndExternalAccess]
from typing import TypeVar, Generic
T = TypeVar('T')

class B(Generic[T]):
    def f(self, a: 'B[T]') -> None: pass
    def __init__(self, x: 'B[T]') -> None:
        self.x = x
class A(B): pass
class C: pass

a: A
c: C
bc: B[C]

a.x = c # E: Incompatible types in assignment (expression has type "C", variable has type "B[Any]")
a.f(c)  # E: Argument 1 to "f" of "B" has incompatible type "C"; expected "B[Any]"
a.x = bc
a.f(bc)
[out]

[case testInheritanceFromGenericWithImplicitDynamic]
from typing import TypeVar, Generic
T = TypeVar('T')
a: A
c: C
bc: B[C]

class B(Generic[T]):
  def f(self, a: 'B[T]') -> None: pass
  def __init__(self, x: 'B[T]') -> None:
    self.x = x

class A(B):
  def g(self) -> None:
    self.x = c # E: Incompatible types in assignment (expression has type "C", variable has type "B[Any]")
    self.f(c)  # E: Argument 1 to "f" of "B" has incompatible type "C"; expected "B[Any]"
    self.x = bc
    self.f(bc)

class C: pass
[out]

[case testInheritanceFromGenericWithImplicitDynamicAndOverriding]
from typing import TypeVar, Generic, Tuple
T = TypeVar('T')
class B(Generic[T]):
    def f(self, a: T, b: 'Tuple[T, B[T]]') -> None:
        pass
class A(B):
    def f(self, a, b): pass
[builtins fixtures/tuple.pyi]
[out]


-- Inheritance from generic types and super expressions
-- ----------------------------------------------------


[case testSuperExpressionsWhenInheritingFromGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
class B(Generic[T]):
    def f(self, a: T) -> None: pass
class A(B[S], Generic[T, S]):
    def g(self, t: T, s: S) -> None:
        super().f(t)   # E: Argument 1 to "f" of "B" has incompatible type "T"; expected "S"
        super().f(s)
[out]

[case testSuperExpressionsWhenInheritingFromGenericTypeAndDeepHierarchy]
from typing import TypeVar, Generic
T = TypeVar('T')
S = TypeVar('S')
U = TypeVar('U')
V = TypeVar('V')
class C(Generic[T, U, V]):
    def f(self, a: V) -> None: pass
class D: pass
class B(C[D, D, T], Generic[T]): pass
class A(B[S], Generic[T, S]):
    def g(self, t: T, s: S) -> None:
        super().f(t)   # E: Argument 1 to "f" of "C" has incompatible type "T"; expected "S"
        super().f(s)
[out]


-- Type of inherited constructor
-- -----------------------------


[case testInheritedConstructor]
from typing import TypeVar, Generic
T = TypeVar('T')
class A(Generic[T]):
    def __init__(self, x: T) -> None: pass
class B(A[T], Generic[T]): pass
class C(A[int]): pass
class D(A[A[T]], Generic[T]): pass
B(1)
C(1)
C('a')  # E: Argument 1 to "C" has incompatible type "str"; expected "int"
D(A(1))
D(1)  # E: Argument 1 to "D" has incompatible type "int"; expected "A[Never]"


[case testInheritedConstructor2]
from typing import TypeVar, Generic
T = TypeVar('T')
U = TypeVar('U')
Z = TypeVar('Z')
class A(Generic[T, U]):
    def __init__(self, x: T, y: U, z: Z) -> None: pass
class B(A[int, T], Generic[T]): pass
class C(B[A[T, str]], Generic[T, U]): pass
# C[T, U] <: B[A[T, str]] <: A[int, A[T, str]]
C(1, A(1, 'a', 0), 'z')
C(1, A('1', 'a', 0), 'z')
C('1', A(1, 'a', 0), 'z')  # E: Argument 1 to "C" has incompatible type "str"; expected "int"
C(1, A(1, 1, 0), 'z')  # E: Argument 2 to "A" has incompatible type "int"; expected "str"


-- Subtyping with a generic abstract base class
-- --------------------------------------------


[case testSubtypingWithGenericTypeSubclassingGenericAbstractClass]
from typing import TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
S = TypeVar('S')
acd: A[C, D]
adc: A[D, C]
ic: I[C]
id: I[D]

if int():
    ic = acd # E: Incompatible types in assignment (expression has type "A[C, D]", variable has type "I[C]")
    id = adc # E: Incompatible types in assignment (expression has type "A[D, C]", variable has type "I[D]")
    adc = ic # E: Incompatible types in assignment (expression has type "I[C]", variable has type "A[D, C]")

if int():
    ic = adc
    id = acd

class I(Generic[T]):
    @abstractmethod
    def f(self): pass
class A(I[S], Generic[T, S]): pass
class C: pass
class D: pass

[case testSubtypingWithTypeImplementingGenericABCViaInheritance]
from typing import TypeVar, Generic
S = TypeVar('S')
a: A
b: B
ic: I[C]
id: I[D]
ie: I[E]

class I(Generic[S]): pass
class B(I[C]): pass
class A(B): pass

if int():
    ie = a # E: Incompatible types in assignment (expression has type "A", variable has type "I[E]")
    a = ic # E: Incompatible types in assignment (expression has type "I[C]", variable has type "A")
if int():
    a = id # E: Incompatible types in assignment (expression has type "I[D]", variable has type "A")
if int():
    a = b  # E: Incompatible types in assignment (expression has type "B", variable has type "A")
    id = a # E: Incompatible types in assignment (expression has type "A", variable has type "I[D]")

    ic = a
    b = a

class C: pass
class D: pass
class E: pass
[builtins fixtures/tuple.pyi]
[out]

[case testSubtypingWithTypeImplementingGenericABCViaInheritance2-skip]
from typing import TypeVar, Generic
T = TypeVar('T')
class I(Generic[T]): pass
class A(I[C]): pass
class B(A, I[D]): pass # Fail

class C: pass
class D: pass
[out]
main:5: error: Class "B" has base "I" duplicated inconsistently

[case testSubtypingAndABCExtension]
from typing import TypeVar, Generic
from abc import abstractmethod, ABCMeta
t = TypeVar('t')
a: A[object]
i: I[object]
j: J[object]
(ii, jj) = (i, j)
if int():
    ii = a
    jj = a
if int():
    jj = i
    a = i # E: Incompatible types in assignment (expression has type "I[object]", variable has type "A[object]")
if int():
    a = j # E: Incompatible types in assignment (expression has type "J[object]", variable has type "A[object]")

class J(Generic[t]): pass
class X(metaclass=ABCMeta): pass
class I(X, J[t], Generic[t]): pass
class A(I[t], Generic[t]): pass
[builtins fixtures/tuple.pyi]


-- Subclassing a generic ABC
-- -------------------------


[case testSubclassingGenericABC1]
from typing import TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
class I(Generic[T]):
    @abstractmethod
    def f(self, a: T) -> None: pass
    @abstractmethod
    def g(self, a: T) -> None: pass
class A(I[C]):
    def f(self, a: 'D') -> None: pass \
        # E: Argument 1 of "f" is incompatible with supertype "I"; supertype defines the argument type as "C" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def g(self, a: 'C') -> None: pass
class C: pass
class D: pass
[out]


-- Extending a generic ABC with deep type hierarchy
-- ------------------------------------------------


[case testSubclassingGenericABCWithDeepHierarchy]
from typing import Any, TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
a: A
ic: I[C]
id: I[D]

if int():
    id = a # E: Incompatible types in assignment (expression has type "A", variable has type "I[D]")
    ic = a

class I(Generic[T]):
    @abstractmethod
    def f(self, a: T, b: T) -> None: pass
    @abstractmethod
    def g(self, a: T, b: 'D') -> None: pass
class B(I[C]):
    def f(self, a: 'C', b: 'C') -> None: pass
    def g(self, a: 'C', b: Any) -> None: pass
class A(B):
    def g(self, a: 'C', b: 'C') -> None: pass \
        # E: Argument 2 of "g" is incompatible with supertype "I"; supertype defines the argument type as "D" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
    def f(self, a: 'C', b: 'C') -> None: pass
class C: pass
class D: pass
[builtins fixtures/tuple.pyi]

[case testSubclassingGenericABCWithDeepHierarchy2]
from typing import Any, TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
class I(Generic[T]):
    @abstractmethod
    def f(self, a: T, b: T) -> None: pass
class B(I[C]):
    def f(self, a: 'C', b: Any) -> None: pass
class A(B):
    def f(self, a: 'C', b: 'D') -> None: pass \
        # E: Argument 2 of "f" is incompatible with supertype "I"; supertype defines the argument type as "C" \
        # N: This violates the Liskov substitution principle \
        # N: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
class C: pass
class D: pass
[out]


-- Implicit Any types and subclassing generic ABC
-- ----------------------------------------------


[case testSubclassingGenericABCWithImplicitAny]
from typing import Any, TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
a: Any
ic: I[C]
id: I[D]

ic = a
id = a

class I(Generic[T]):
    @abstractmethod
    def f(self, a: T) -> None: pass
class A(I):
    def f(self, a): pass

class C: pass
class D: pass

[case testSubclassingGenericABCWithImplicitAnyAndDeepHierarchy]
from typing import Any, TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
a: Any
ic: I[C]
id: I[D]

ic = a
id = a

class I(Generic[T]):
    @abstractmethod
    def f(self, a: T, b: T) -> None: pass
class B(I):
    def f(self, a, b): pass
class A(B):
    def f(self, a: 'C', b: 'D') -> None: pass
class C: pass
class D: pass

[case testImplementingGenericABCWithImplicitAnyAndDeepHierarchy2]
from typing import Any, TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
a: Any
jc: J[C]
jd: J[D]

jc = a
jd = a

class J(Generic[T]):
    @abstractmethod
    def f(self, a: T, b: T) -> None: pass
class I(J):
    @abstractmethod
    def f(self, a, b): pass
class A(I):
    def f(self, a: 'C', b: 'D') -> None: pass

class C: pass
class D: pass


-- Accessing generic ABC members
-- -----------------------------


[case testAccessingGenericABCMembers]
from typing import TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
class I(Generic[T]):
    @abstractmethod
    def f(self, a: T) -> None: pass
class A: pass
class B: pass

a: A
b: B
ia: I[A]

ia.f(b)  # E: Argument 1 to "f" of "I" has incompatible type "B"; expected "A"
ia.f(a)
[builtins fixtures/tuple.pyi]

[case testAccessingInheritedGenericABCMembers]
from typing import TypeVar, Generic
from abc import abstractmethod
T = TypeVar('T')
class J(Generic[T]):
    @abstractmethod
    def f(self, a: T) -> None: pass
class I(J[T], Generic[T]): pass
class A: pass
class B: pass
a: A
b: B
ia: I[A]

ia.f(b)  # E: Argument 1 to "f" of "J" has incompatible type "B"; expected "A"
ia.f(a)
[builtins fixtures/tuple.pyi]


-- Misc
-- ----


[case testMultipleAssignmentAndGenericSubtyping]
from typing import Iterable
n: int
s: str
class Nums(Iterable[int]):
    def __iter__(self): pass
    def __next__(self): pass
n, n = Nums()
s, s = Nums() # E: Incompatible types in assignment (expression has type "int", variable has type "str")
[builtins fixtures/for.pyi]
[out]

[case testUninhabitedCacheChecksAmbiguous]
# https://github.com/python/mypy/issues/19641
from typing import Mapping, Never, TypeVar

M = TypeVar("M", bound=Mapping[str,object])

def get(arg: M, /) -> M:
    return arg

get({})

def upcast(d: dict[Never, Never]) -> Mapping[str, object]:
    return d  # E: Incompatible return value type (got "dict[Never, Never]", expected "Mapping[str, object]")
[builtins fixtures/dict.pyi]

-- Variance
-- --------


[case testCovariant]
from typing import TypeVar, Generic
T = TypeVar('T', covariant=True)

class G(Generic[T]): pass
class A: pass
class B(A): pass
class C(B): pass

a: G[A]
b: G[B]
c: G[C]

if int():
    b = a  # E: Incompatible types in assignment (expression has type "G[A]", variable has type "G[B]")
    b = c
[builtins fixtures/bool.pyi]
[out]

[case testContravariant]
from typing import TypeVar, Generic
T = TypeVar('T', contravariant=True)

class G(Generic[T]): pass
class A: pass
class B(A): pass
class C(B): pass

a: G[A]
b: G[B]
c: G[C]

if int():
    b = a
    b = c  # E: Incompatible types in assignment (expression has type "G[C]", variable has type "G[B]")
[builtins fixtures/bool.pyi]
[out]

[case testInvariant]
from typing import TypeVar, Generic
T = TypeVar('T')  # invariant (default)

class G(Generic[T]): pass
class A: pass
class B(A): pass
class C(B): pass

a: G[A]
b: G[B]
c: G[C]

if int():
    b = a  # E: Incompatible types in assignment (expression has type "G[A]", variable has type "G[B]")
    b = c  # E: Incompatible types in assignment (expression has type "G[C]", variable has type "G[B]")
[builtins fixtures/bool.pyi]
[out]


[case testTypeVarSubtypeUnion]
from typing import Union, TypeVar, Generic

class U: pass
class W: pass

T = TypeVar('T', bound=Union[U, W])

class Y(Generic[T]):
    def __init__(self) -> None:
        pass
    def f(self) -> T:
        return U()  # E: Incompatible return value type (got "U", expected "T")


[case testTypeVarBoundToOldUnionAttributeAccess]
from typing import Union, TypeVar

class U:
    a: float
class V:
    b: float
class W:
    c: float

T = TypeVar("T", bound=Union[U, V, W])

def f(x: T) -> None:
    x.a  # E
    x.b = 1.0  # E
    del x.c  # E

[out]
main:13: error: Item "V" of the upper bound "U | V | W" of type variable "T" has no attribute "a"
main:13: error: Item "W" of the upper bound "U | V | W" of type variable "T" has no attribute "a"
main:14: error: Item "U" of the upper bound "U | V | W" of type variable "T" has no attribute "b"
main:14: error: Item "W" of the upper bound "U | V | W" of type variable "T" has no attribute "b"
main:15: error: Item "U" of the upper bound "U | V | W" of type variable "T" has no attribute "c"
main:15: error: Item "V" of the upper bound "U | V | W" of type variable "T" has no attribute "c"


[case testTypeVarBoundToNewUnionAttributeAccess]
from typing import TypeVar

class U:
    a: int
class V:
    b: int
class W:
    c: int

T = TypeVar("T", bound=U | V | W)

def f(x: T) -> None:
    x.a  # E
    x.b = 1  # E
    del x.c  # E

[builtins fixtures/tuple.pyi]
[out]
main:13: error: Item "V" of the upper bound "U | V | W" of type variable "T" has no attribute "a"
main:13: error: Item "W" of the upper bound "U | V | W" of type variable "T" has no attribute "a"
main:14: error: Item "U" of the upper bound "U | V | W" of type variable "T" has no attribute "b"
main:14: error: Item "W" of the upper bound "U | V | W" of type variable "T" has no attribute "b"
main:15: error: Item "U" of the upper bound "U | V | W" of type variable "T" has no attribute "c"
main:15: error: Item "V" of the upper bound "U | V | W" of type variable "T" has no attribute "c"


[case testSubtypingIterableUnpacking1]
# https://github.com/python/mypy/issues/11138
from typing import Generic, Iterator, TypeVar
T = TypeVar("T")
U = TypeVar("U")

class X1(Iterator[U], Generic[T, U]):
    pass

x1: X1[str, int]
reveal_type(list(x1))  # N: Revealed type is "builtins.list[builtins.int]"
reveal_type([*x1])  # N: Revealed type is "builtins.list[builtins.int]"

class X2(Iterator[T], Generic[T, U]):
    pass

x2: X2[str, int]
reveal_type(list(x2))  # N: Revealed type is "builtins.list[builtins.str]"
reveal_type([*x2])  # N: Revealed type is "builtins.list[builtins.str]"

class X3(Generic[T, U], Iterator[U]):
    pass

x3: X3[str, int]
reveal_type(list(x3))  # N: Revealed type is "builtins.list[builtins.int]"
reveal_type([*x3])  # N: Revealed type is "builtins.list[builtins.int]"

class X4(Generic[T, U], Iterator[T]):
    pass

x4: X4[str, int]
reveal_type(list(x4))  # N: Revealed type is "builtins.list[builtins.str]"
reveal_type([*x4])  # N: Revealed type is "builtins.list[builtins.str]"

class X5(Iterator[T]):
    pass

x5: X5[str]
reveal_type(list(x5))  # N: Revealed type is "builtins.list[builtins.str]"
reveal_type([*x5])  # N: Revealed type is "builtins.list[builtins.str]"

class X6(Generic[T, U], Iterator[bool]):
    pass

x6: X6[str, int]
reveal_type(list(x6))  # N: Revealed type is "builtins.list[builtins.bool]"
reveal_type([*x6])  # N: Revealed type is "builtins.list[builtins.bool]"
[builtins fixtures/list.pyi]

[case testSubtypingIterableUnpacking2]
from typing import Generic, Iterator, TypeVar, Mapping
T = TypeVar("T")
U = TypeVar("U")

class X1(Generic[T, U], Iterator[U], Mapping[U, T]):
    pass

x1: X1[str, int]
reveal_type(list(x1))  # N: Revealed type is "builtins.list[builtins.int]"
reveal_type([*x1])  # N: Revealed type is "builtins.list[builtins.int]"

class X2(Generic[T, U], Iterator[U], Mapping[T, U]):
    pass

x2: X2[str, int]
reveal_type(list(x2))  # N: Revealed type is "builtins.list[builtins.int]"
reveal_type([*x2])  # N: Revealed type is "builtins.list[builtins.int]"
[builtins fixtures/list.pyi]

[case testSubtypingMappingUnpacking1]
# https://github.com/python/mypy/issues/11138
from typing import Generic, TypeVar, Mapping
T = TypeVar("T")
U = TypeVar("U")

class X1(Generic[T, U],  Mapping[U, T]):
    pass

x1: X1[str, int]
reveal_type(iter(x1))  # N: Revealed type is "typing.Iterator[builtins.int]"
reveal_type({**x1})  # N: Revealed type is "builtins.dict[builtins.int, builtins.str]"

class X2(Generic[T, U],  Mapping[T, U]):
    pass

x2: X2[str, int]
reveal_type(iter(x2))  # N: Revealed type is "typing.Iterator[builtins.str]"
reveal_type({**x2})  # N: Revealed type is "builtins.dict[builtins.str, builtins.int]"

class X3(Generic[T, U],  Mapping[bool, float]):
    pass

x3: X3[str, int]
reveal_type(iter(x3))  # N: Revealed type is "typing.Iterator[builtins.bool]"
reveal_type({**x3})  # N: Revealed type is "builtins.dict[builtins.bool, builtins.float]"
[builtins fixtures/dict.pyi]

[case testSubtypingMappingUnpacking2]
from typing import Generic, TypeVar, Mapping
T = TypeVar("T")
U = TypeVar("U")

class X1(Generic[T, U],  Mapping[U, T]):
    pass

def func_with_kwargs(**kwargs: int):
    pass

x1: X1[str, int]
reveal_type(iter(x1))
reveal_type({**x1})
func_with_kwargs(**x1)
[out]
main:12: note: Revealed type is "typing.Iterator[builtins.int]"
main:13: note: Revealed type is "builtins.dict[builtins.int, builtins.str]"
main:14: error: Argument after ** must have string keys
main:14: error: Argument 1 to "func_with_kwargs" has incompatible type "**X1[str, int]"; expected "int"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-medium.pyi]

[case testSubtypingMappingUnpacking3]
from typing import Generic, TypeVar, Mapping, Iterable
T = TypeVar("T")
U = TypeVar("U")

class X1(Generic[T, U],  Mapping[U, T], Iterable[U]):
    pass

x1: X1[str, int]
reveal_type(iter(x1))  # N: Revealed type is "typing.Iterator[builtins.int]"
reveal_type({**x1})  # N: Revealed type is "builtins.dict[builtins.int, builtins.str]"

# Some people would expect this to raise an error, but this currently does not:
# `Mapping` has `Iterable[U]` base class, `X2` has direct `Iterable[T]` base class.
# It would be impossible to define correct `__iter__` method for incompatible `T` and `U`.
class X2(Generic[T, U],  Mapping[U, T], Iterable[T]):
    pass

x2: X2[str, int]
reveal_type(iter(x2))  # N: Revealed type is "typing.Iterator[builtins.int]"
reveal_type({**x2})  # N: Revealed type is "builtins.dict[builtins.int, builtins.str]"
[builtins fixtures/dict.pyi]

[case testNotDirectIterableAndMappingSubtyping]
from typing import Generic, TypeVar, Dict, Iterable, Iterator, List
T = TypeVar("T")
U = TypeVar("U")

class X1(Generic[T, U], Dict[U, T], Iterable[U]):
    def __iter__(self) -> Iterator[U]: pass

x1: X1[str, int]
reveal_type(iter(x1))  # N: Revealed type is "typing.Iterator[builtins.int]"
reveal_type({**x1})  # N: Revealed type is "builtins.dict[builtins.int, builtins.str]"

class X2(Generic[T, U], List[U]):
    def __iter__(self) -> Iterator[U]: pass

x2: X2[str, int]
reveal_type(iter(x2))  # N: Revealed type is "typing.Iterator[builtins.int]"
reveal_type([*x2])  # N: Revealed type is "builtins.list[builtins.int]"
[builtins fixtures/dict.pyi]

[case testIncompatibleVariance]
from typing import TypeVar, Generic
T = TypeVar('T')
T_co = TypeVar('T_co', covariant=True)
T_contra = TypeVar('T_contra', contravariant=True)

class A(Generic[T_co]): ...
class B(A[T_contra], Generic[T_contra]): ...  # E: Variance of TypeVar "T_contra" incompatible with variance in parent type

class C(Generic[T_contra]): ...
class D(C[T_co], Generic[T_co]): ...  # E: Variance of TypeVar "T_co" incompatible with variance in parent type

class E(Generic[T]): ...
class F(E[T_co], Generic[T_co]): ...  # E: Variance of TypeVar "T_co" incompatible with variance in parent type

class G(Generic[T]): ...
class H(G[T_contra], Generic[T_contra]): ...  # E: Variance of TypeVar "T_contra" incompatible with variance in parent type

[case testParameterizedGenericOverrideWithProperty]
from typing import TypeVar, Generic

T = TypeVar("T")

class A(Generic[T]):
    def __init__(self, val: T):
        self.member: T = val

class B(A[str]):
    member: str

class GoodPropertyOverride(A[str]):
    @property
    def member(self) -> str: ...
    @member.setter
    def member(self, val: str): ...

class BadPropertyOverride(A[str]):
    @property  # E: Signature of "member" incompatible with supertype "A" \
               # N:      Superclass: \
               # N:          str \
               # N:      Subclass: \
               # N:          int
    def member(self) -> int: ...
    @member.setter
    def member(self, val: int): ...

class BadGenericPropertyOverride(A[str], Generic[T]):
    @property  # E: Signature of "member" incompatible with supertype "A" \
               # N:      Superclass: \
               # N:          str \
               # N:      Subclass: \
               # N:          T
    def member(self) -> T: ...
    @member.setter
    def member(self, val: T): ...
[builtins fixtures/property.pyi]

[case testParameterizedGenericPropertyOverrideWithProperty]
from typing import TypeVar, Generic

T = TypeVar("T")

class A(Generic[T]):
    @property
    def member(self) -> T: ...
    @member.setter
    def member(self, val: T): ...

class B(A[str]):
    member: str

class GoodPropertyOverride(A[str]):
    @property
    def member(self) -> str: ...
    @member.setter
    def member(self, val: str): ...

class BadPropertyOverride(A[str]):
    @property  # E: Signature of "member" incompatible with supertype "A" \
               # N:      Superclass: \
               # N:          str \
               # N:      Subclass: \
               # N:          int
    def member(self) -> int: ...
    @member.setter
    def member(self, val: int): ...

class BadGenericPropertyOverride(A[str], Generic[T]):
    @property  # E: Signature of "member" incompatible with supertype "A" \
               # N:      Superclass: \
               # N:          str \
               # N:      Subclass: \
               # N:          T
    def member(self) -> T: ...
    @member.setter
    def member(self, val: T): ...
[builtins fixtures/property.pyi]

[case testParameterizedGenericOverrideSelfWithProperty]
from typing_extensions import Self

class A:
    def __init__(self, val: Self):
        self.member: Self = val

class GoodPropertyOverride(A):
    @property
    def member(self) -> "GoodPropertyOverride": ...
    @member.setter
    def member(self, val: "GoodPropertyOverride"): ...

class GoodPropertyOverrideSelf(A):
    @property
    def member(self) -> Self: ...
    @member.setter
    def member(self, val: Self): ...
[builtins fixtures/property.pyi]

[case testParameterizedGenericOverrideWithSelfProperty]
from typing import TypeVar, Generic
from typing_extensions import Self

T = TypeVar("T")

class A(Generic[T]):
    def __init__(self, val: T):
        self.member: T = val

class B(A["B"]):
    member: Self

class GoodPropertyOverride(A["GoodPropertyOverride"]):
    @property
    def member(self) -> Self: ...
    @member.setter
    def member(self, val: Self): ...
[builtins fixtures/property.pyi]

[case testMultipleInheritanceCompatibleTypeVar]
from typing import Generic, TypeVar

T = TypeVar("T")
U = TypeVar("U")

class A(Generic[T]):
    x: T
    def fn(self, t: T) -> None: ...

class A2(A[T]):
    y: str
    z: str

class B(Generic[T]):
    x: T
    def fn(self, t: T) -> None: ...

class C1(A2[str], B[str]): pass
class C2(A2[str], B[int]): pass  # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B" \
                                 # E: Definition of "x" in base class "A" is incompatible with definition in base class "B"
class C3(A2[T], B[T]): pass
class C4(A2[U], B[U]): pass
class C5(A2[U], B[T]): pass  # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B" \
                             # E: Definition of "x" in base class "A" is incompatible with definition in base class "B"

class D1(A[str], B[str]): pass
class D2(A[str], B[int]): pass  # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B" \
                                # E: Definition of "x" in base class "A" is incompatible with definition in base class "B"
class D3(A[T], B[T]): pass
class D4(A[U], B[U]): pass
class D5(A[U], B[T]): pass  # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B" \
                            # E: Definition of "x" in base class "A" is incompatible with definition in base class "B"
[builtins fixtures/tuple.pyi]