test-data/unit/check-dataclasses.test

[case testDataclassesBasic]
from dataclasses import dataclass

@dataclass
class Person:
    name: str
    age: int

    def summary(self):
        return "%s is %d years old." % (self.name, self.age)

reveal_type(Person)  # N: Revealed type is "def (name: builtins.str, age: builtins.int) -> __main__.Person"
Person('John', 32)
Person('Jonh', 21, None)  # E: Too many arguments for "Person"

[builtins fixtures/dataclasses.pyi]
[typing fixtures/typing-medium.pyi]

[case testDataclassesCustomInit]
from dataclasses import dataclass

@dataclass
class A:
    a: int

    def __init__(self, a: str) -> None:
        pass

A('1')

[builtins fixtures/dataclasses.pyi]

[case testDataclassesBasicInheritance]
from dataclasses import dataclass

@dataclass
class Mammal:
    age: int

@dataclass
class Person(Mammal):
    name: str

    def summary(self):
        return "%s is %d years old." % (self.name, self.age)

reveal_type(Person)  # N: Revealed type is "def (age: builtins.int, name: builtins.str) -> __main__.Person"
Mammal(10)
Person(32, 'John')
Person(21, 'Jonh', None)  # E: Too many arguments for "Person"

[builtins fixtures/dataclasses.pyi]
[typing fixtures/typing-medium.pyi]

[case testDataclassesDeepInheritance]
from dataclasses import dataclass

@dataclass
class A:
    a: int

@dataclass
class B(A):
    b: int

@dataclass
class C(B):
    c: int

@dataclass
class D(C):
    d: int

reveal_type(A)  # N: Revealed type is "def (a: builtins.int) -> __main__.A"
reveal_type(B)  # N: Revealed type is "def (a: builtins.int, b: builtins.int) -> __main__.B"
reveal_type(C)  # N: Revealed type is "def (a: builtins.int, b: builtins.int, c: builtins.int) -> __main__.C"
reveal_type(D)  # N: Revealed type is "def (a: builtins.int, b: builtins.int, c: builtins.int, d: builtins.int) -> __main__.D"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesMultipleInheritance]
from dataclasses import dataclass, field, InitVar
@dataclass
class A:
    a: bool

@dataclass
class B:
    b: InitVar[bool]
    _b: bool = field(init=False)

    def __post_init__(self, b: bool):
        self._b = b

@dataclass
class C(A, B):
    pass

reveal_type(C)  # N: Revealed type is "def (b: builtins.bool, a: builtins.bool) -> __main__.C"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDeepInitVarInheritance]
from dataclasses import dataclass, field, InitVar
@dataclass
class A:
    a: bool

@dataclass
class B:
    b: InitVar[bool]
    _b: bool = field(init=False)

    def __post_init__(self, b: bool):
        self._b = b

@dataclass(init=False)
class C(B):
    def __init__(self):
        super().__init__(True)

@dataclass
class D(C):
    pass

reveal_type(C)  # N: Revealed type is "def () -> __main__.C"
reveal_type(D)  # N: Revealed type is "def (b: builtins.bool) -> __main__.D"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOverriding]
from dataclasses import dataclass

@dataclass
class Mammal:
    age: int

@dataclass
class Person(Mammal):
    name: str
    age: int

@dataclass
class SpecialPerson(Person):
    special_factor: float

@dataclass
class ExtraSpecialPerson(SpecialPerson):
    age: int
    special_factor: float
    name: str

reveal_type(Person)  # N: Revealed type is "def (age: builtins.int, name: builtins.str) -> __main__.Person"
reveal_type(SpecialPerson)  # N: Revealed type is "def (age: builtins.int, name: builtins.str, special_factor: builtins.float) -> __main__.SpecialPerson"
reveal_type(ExtraSpecialPerson)  # N: Revealed type is "def (age: builtins.int, name: builtins.str, special_factor: builtins.float) -> __main__.ExtraSpecialPerson"
Person(32, 'John')
Person(21, 'John', None)  # E: Too many arguments for "Person"
SpecialPerson(21, 'John', 0.5)
ExtraSpecialPerson(21, 'John', 0.5)

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOverridingWithDefaults]
# Issue #5681 https://github.com/python/mypy/issues/5681
from dataclasses import dataclass
from typing import Any

@dataclass
class Base:
    some_int: Any
    some_str: str = 'foo'


@dataclass
class C(Base):
    some_int: int

reveal_type(C)  # N: Revealed type is "def (some_int: builtins.int, some_str: builtins.str =) -> __main__.C"

[builtins fixtures/dataclasses.pyi]

[case testDataclassIncompatibleOverrides]
from dataclasses import dataclass

@dataclass
class Base:
    foo: int

@dataclass
class BadDerived1(Base):
    def foo(self) -> int:  # E: Dataclass attribute may only be overridden by another attribute \
                           # E: Signature of "foo" incompatible with supertype "Base" \
                           # N:      Superclass: \
                           # N:          int \
                           # N:      Subclass: \
                           # N:          def foo(self) -> int
        return 1

@dataclass
class BadDerived2(Base):
    @property              # E: Dataclass attribute may only be overridden by another attribute
    def foo(self) -> int:  # E: Cannot override writeable attribute with read-only property
        return 2

@dataclass
class BadDerived3(Base):
    class foo: pass  # E: Dataclass attribute may only be overridden by another attribute
[builtins fixtures/dataclasses.pyi]

[case testDataclassMultipleInheritance]
from dataclasses import dataclass

class Unrelated:
    foo: str

@dataclass
class Base:
    bar: int

@dataclass
class Derived(Base, Unrelated):
    pass

d = Derived(3)
reveal_type(d.foo)  # N: Revealed type is "builtins.str"
reveal_type(d.bar)  # N: Revealed type is "builtins.int"
[builtins fixtures/dataclasses.pyi]

[case testDataclassIncompatibleFrozenOverride]
from dataclasses import dataclass

@dataclass(frozen=True)
class Base:
    foo: int

@dataclass(frozen=True)
class BadDerived(Base):
    @property  # E: Dataclass attribute may only be overridden by another attribute
    def foo(self) -> int:
        return 3
[builtins fixtures/dataclasses.pyi]

[case testDataclassesFreezing]
from dataclasses import dataclass

@dataclass(frozen=True)
class Person:
    name: str

john = Person('John')
john.name = 'Ben'  # E: Property "name" defined in "Person" is read-only

[builtins fixtures/dataclasses.pyi]

[case testDataclassesInconsistentFreezing]
from dataclasses import dataclass

@dataclass(frozen=True)
class FrozenBase:
    pass

@dataclass
class BadNormalDerived(FrozenBase):  # E: Cannot inherit non-frozen dataclass from a frozen one
    pass

@dataclass
class NormalBase:
    pass

@dataclass(frozen=True)
class BadFrozenDerived(NormalBase):  # E: Cannot inherit frozen dataclass from a non-frozen one
    pass

[builtins fixtures/dataclasses.pyi]

[case testDataclassesFields]
from dataclasses import dataclass, field

@dataclass
class Person:
    name: str
    age: int = field(default=0, init=False)

reveal_type(Person)  # N: Revealed type is "def (name: builtins.str) -> __main__.Person"
john = Person('John')
john.age = 'invalid'  # E: Incompatible types in assignment (expression has type "str", variable has type "int")
john.age = 24

[builtins fixtures/dataclasses.pyi]

[case testDataclassesBadInit]
from dataclasses import dataclass, field

@dataclass
class Person:
    name: str
    age: int = field(init=None)  # E: No overload variant of "field" matches argument type "None" \
                                 # N: Possible overload variants: \
                                 # N:     def [_T] field(*, default: _T, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T \
                                 # N:     def [_T] field(*, default_factory: Callable[[], _T], init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T \
                                 # N:     def field(*, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> Any

[builtins fixtures/dataclasses.pyi]

[case testDataclassesMultiInit]
from dataclasses import dataclass, field
from typing import List

@dataclass
class Person:
    name: str
    age: int = field(init=False)
    friend_names: List[str] = field(init=True)
    enemy_names: List[str]

reveal_type(Person)  # N: Revealed type is "def (name: builtins.str, friend_names: builtins.list[builtins.str], enemy_names: builtins.list[builtins.str]) -> __main__.Person"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesMultiInitDefaults]
from dataclasses import dataclass, field
from typing import List, Optional

@dataclass
class Person:
    name: str
    age: int = field(init=False)
    friend_names: List[str] = field(init=True)
    enemy_names: List[str]
    nickname: Optional[str] = None

reveal_type(Person)  # N: Revealed type is "def (name: builtins.str, friend_names: builtins.list[builtins.str], enemy_names: builtins.list[builtins.str], nickname: Union[builtins.str, None] =) -> __main__.Person"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaults]
from dataclasses import dataclass

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int = 0

reveal_type(Application)  # N: Revealed type is "def (name: builtins.str =, rating: builtins.int =) -> __main__.Application"
app = Application()

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaultFactories]
from dataclasses import dataclass, field

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int = field(default_factory=int)
    rating_count: int = field()  # E: Attributes without a default cannot follow attributes with one

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaultFactoryTypeChecking]
from dataclasses import dataclass, field

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int = field(default_factory=str)  # E: Incompatible types in assignment (expression has type "str", variable has type "int")

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaultOrdering]
from dataclasses import dataclass

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int  # E: Attributes without a default cannot follow attributes with one

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnly]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass(kw_only=True)
class Application:
    name: str = 'Unnamed'
    rating: int

Application(rating=5)
Application(name='name', rating=5)
Application()  # E: Missing named argument "rating" for "Application"
Application('name')  # E: Too many positional arguments for "Application" # E: Missing named argument "rating" for "Application"
Application('name', 123)  # E: Too many positional arguments for "Application"
Application('name', rating=123)  # E: Too many positional arguments for "Application"
Application(name=123, rating='name') # E: Argument "name" to "Application" has incompatible type "int"; expected "str" # E: Argument "rating" to "Application" has incompatible type "str"; expected "int"
Application(rating='name', name=123) # E: Argument "rating" to "Application" has incompatible type "str"; expected "int" # E: Argument "name" to "Application" has incompatible type "int"; expected "str"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyOnField]
# flags: --python-version 3.10
from dataclasses import dataclass, field

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int = field(kw_only=True)

Application(rating=5)
Application('name', rating=123)
Application(name='name', rating=5)
Application()  # E: Missing named argument "rating" for "Application"
Application('name')  # E: Missing named argument "rating" for "Application"
Application('name', 123)  # E: Too many positional arguments for "Application"
Application(123, rating='name') # E: Argument 1 to "Application" has incompatible type "int"; expected "str" # E: Argument "rating" to "Application" has incompatible type "str"; expected "int"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyOnFieldFalse]
# flags: --python-version 3.10
from dataclasses import dataclass, field

@dataclass
class Application:
    name: str = 'Unnamed'
    rating: int = field(kw_only=False)  # E: Attributes without a default cannot follow attributes with one

Application(name='name', rating=5)
Application('name', 123)
Application('name', rating=123)
Application()  # E: Missing positional argument "name" in call to "Application"
Application('name')  # E: Too few arguments for "Application"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyWithSentinel]
# flags: --python-version 3.10
from dataclasses import dataclass, KW_ONLY

@dataclass
class Application:
    _: KW_ONLY
    name: str = 'Unnamed'
    rating: int

Application(rating=5)
Application(name='name', rating=5)
Application()  # E: Missing named argument "rating" for "Application"
Application('name')  # E: Too many positional arguments for "Application" # E: Missing named argument "rating" for "Application"
Application('name', 123)  # E: Too many positional arguments for "Application"
Application('name', rating=123)  # E: Too many positional arguments for "Application"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyWithSentinelAndFieldOverride]
# flags: --python-version 3.10
from dataclasses import dataclass, field, KW_ONLY

@dataclass
class Application:
    _: KW_ONLY
    name: str = 'Unnamed'
    rating: int = field(kw_only=False)  # E: Attributes without a default cannot follow attributes with one

Application(name='name', rating=5)
Application()  # E: Missing positional argument "name" in call to "Application"
Application('name')  # E: Too many positional arguments for "Application" # E: Too few arguments for "Application"
Application('name', 123)  # E: Too many positional arguments for "Application"
Application('name', rating=123)  # E: Too many positional arguments for "Application"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyWithSentinelAndSubclass]
# flags: --python-version 3.10
from dataclasses import dataclass, field, KW_ONLY

@dataclass
class Base:
    x: str
    _: KW_ONLY
    y: int = 0
    w: int = 1

@dataclass
class D(Base):
    z: str
    a: str = "a"

D("Hello", "World")
D(x="Hello", z="World")
D("Hello", "World", y=1, w=2, a="b")
D("Hello")  # E: Missing positional argument "z" in call to "D"
D()  # E: Missing positional arguments "x", "z" in call to "D"
D(123, "World")  # E: Argument 1 to "D" has incompatible type "int"; expected "str"
D("Hello", False)  # E: Argument 2 to "D" has incompatible type "bool"; expected "str"
D(123, False)  # E: Argument 1 to "D" has incompatible type "int"; expected "str" # E: Argument 2 to "D" has incompatible type "bool"; expected "str"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOrderingKwOnlyWithMultipleSentinel]
# flags: --python-version 3.10
from dataclasses import dataclass, field, KW_ONLY

@dataclass
class Base:
    x: str
    _: KW_ONLY
    y: int = 0
    __: KW_ONLY  # E: There may not be more than one field with the KW_ONLY type
    w: int = 1

[builtins fixtures/dataclasses.pyi]

[case testDataclassesClassmethods]
from dataclasses import dataclass

@dataclass
class Application:
    name: str

    @classmethod
    def parse(cls, request: str) -> "Application":
        return cls(name='...')

app = Application.parse('')

[builtins fixtures/dataclasses.pyi]

[case testDataclassesOverloadsAndClassmethods]
from dataclasses import dataclass
from typing import overload, Union

@dataclass
class A:
    a: int
    b: str

    @classmethod
    def other(cls) -> str:
        return "..."

    @overload
    @classmethod
    def foo(cls, x: int) -> int: ...

    @overload
    @classmethod
    def foo(cls, x: str) -> str: ...

    @classmethod
    def foo(cls, x: Union[int, str]) -> Union[int, str]:
        reveal_type(cls)            # N: Revealed type is "Type[__main__.A]"
        reveal_type(cls.other())    # N: Revealed type is "builtins.str"
        return x

reveal_type(A.foo(3))      # N: Revealed type is "builtins.int"
reveal_type(A.foo("foo"))  # N: Revealed type is "builtins.str"

[builtins fixtures/dataclasses.pyi]

[case testClassmethodShadowingFieldDoesNotCrash]
from dataclasses import dataclass

# This used to crash -- see #6217
@dataclass
class Foo:
    bar: str
    @classmethod  # E: Name "bar" already defined on line 6
    def bar(cls) -> "Foo":
        return cls('asdf')
[builtins fixtures/dataclasses.pyi]

[case testDataclassesClassVars]
from dataclasses import dataclass
from typing import ClassVar

@dataclass
class Application:
  name: str

  COUNTER: ClassVar[int] = 0

reveal_type(Application)  # N: Revealed type is "def (name: builtins.str) -> __main__.Application"
application = Application("example")
application.COUNTER = 1  # E: Cannot assign to class variable "COUNTER" via instance
Application.COUNTER = 1

[builtins fixtures/dataclasses.pyi]

[case testTypeAliasInDataclassDoesNotCrash]
from dataclasses import dataclass
from typing import Callable
from typing_extensions import TypeAlias

@dataclass
class Foo:
    x: int

@dataclass
class One:
    S: TypeAlias = Foo  # E: Type aliases inside dataclass definitions are not supported at runtime

a = One()
reveal_type(a.S)  # N: Revealed type is "def (x: builtins.int) -> __main__.Foo"
a.S()  # E: Missing positional argument "x" in call to "Foo"
reveal_type(a.S(5))  # N: Revealed type is "__main__.Foo"

@dataclass
class Two:
    S: TypeAlias = Callable[[int], str]  # E: Type aliases inside dataclass definitions are not supported at runtime

c = Two()
x = c.S
reveal_type(x)  # N: Revealed type is "typing._SpecialForm"
[builtins fixtures/dataclasses.pyi]
[typing fixtures/typing-medium.pyi]

[case testDataclassOrdering]
from dataclasses import dataclass

@dataclass(order=True)
class Application:
  name: str
  rating: int

app1 = Application('example-1', 5)
app2 = Application('example-2', 5)
app1 < app2
app1 > app2
app1 <= app2
app1 >= app2
app1 < 5  # E: Unsupported operand types for < ("Application" and "int")
app1 > 5  # E: Unsupported operand types for > ("Application" and "int")
app1 <= 5  # E: Unsupported operand types for <= ("Application" and "int")
app1 >= 5  # E: Unsupported operand types for >= ("Application" and "int")

class SpecializedApplication(Application):
  ...

app3 = SpecializedApplication('example-3', 5)
app1 < app3
app1 > app3
app1 <= app3
app1 >= app3

[builtins fixtures/dataclasses.pyi]

[case testDataclassOrderingWithoutEquality]
from dataclasses import dataclass

@dataclass(eq=False, order=True)  # E: "eq" must be True if "order" is True
class Application:
   ...

[builtins fixtures/dataclasses.pyi]

[case testDataclassOrderingWithCustomMethods]
from dataclasses import dataclass

@dataclass(order=True)
class Application:
  def __lt__(self, other: 'Application') -> bool: # E: You may not have a custom "__lt__" method when "order" is True
    ...

[builtins fixtures/dataclasses.pyi]

[case testDataclassDefaultsInheritance]
from dataclasses import dataclass
from typing import Optional

@dataclass(order=True)
class Application:
  id: Optional[int]
  name: str

@dataclass
class SpecializedApplication(Application):
  rating: int = 0

reveal_type(SpecializedApplication)  # N: Revealed type is "def (id: Union[builtins.int, None], name: builtins.str, rating: builtins.int =) -> __main__.SpecializedApplication"

[builtins fixtures/dataclasses.pyi]

[case testDataclassGenerics]
from dataclasses import dataclass
from typing import Generic, List, Optional, TypeVar

T = TypeVar('T')

@dataclass
class A(Generic[T]):
  x: T
  y: T
  z: List[T]

  def foo(self) -> List[T]:
    return [self.x, self.y]

  def bar(self) -> T:
    return self.z[0]

  def problem(self) -> T:
    return self.z  # E: Incompatible return value type (got "List[T]", expected "T")

reveal_type(A)  # N: Revealed type is "def [T] (x: T`1, y: T`1, z: builtins.list[T`1]) -> __main__.A[T`1]"
A(1, 2, ["a", "b"])  # E: Cannot infer type argument 1 of "A"
a = A(1, 2, [1, 2])
reveal_type(a)  # N: Revealed type is "__main__.A[builtins.int]"
reveal_type(a.x)  # N: Revealed type is "builtins.int"
reveal_type(a.y)  # N: Revealed type is "builtins.int"
reveal_type(a.z)  # N: Revealed type is "builtins.list[builtins.int]"
s: str = a.bar()  # E: Incompatible types in assignment (expression has type "int", variable has type "str")

[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericCovariant]
from dataclasses import dataclass
from typing import Generic, TypeVar

T_co = TypeVar("T_co", covariant=True)

@dataclass
class MyDataclass(Generic[T_co]):
    a: T_co

[builtins fixtures/dataclasses.pyi]

[case testDataclassUntypedGenericInheritance]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar("T")

@dataclass
class Base(Generic[T]):
    attr: T

@dataclass
class Sub(Base):
    pass

sub = Sub(attr=1)
reveal_type(sub)  # N: Revealed type is "__main__.Sub"
reveal_type(sub.attr)  # N: Revealed type is "Any"

[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericSubtype]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar("T")

@dataclass
class Base(Generic[T]):
    attr: T

S = TypeVar("S")

@dataclass
class Sub(Base[S]):
    pass

sub_int = Sub[int](attr=1)
reveal_type(sub_int)  # N: Revealed type is "__main__.Sub[builtins.int]"
reveal_type(sub_int.attr)  # N: Revealed type is "builtins.int"

sub_str = Sub[str](attr='ok')
reveal_type(sub_str)  # N: Revealed type is "__main__.Sub[builtins.str]"
reveal_type(sub_str.attr)  # N: Revealed type is "builtins.str"

[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericInheritance]
from dataclasses import dataclass
from typing import Generic, TypeVar

T1 = TypeVar("T1")
T2 = TypeVar("T2")
T3 = TypeVar("T3")

@dataclass
class Base(Generic[T1, T2, T3]):
    one: T1
    two: T2
    three: T3

@dataclass
class Sub(Base[int, str, float]):
    pass

sub = Sub(one=1, two='ok', three=3.14)
reveal_type(sub)  # N: Revealed type is "__main__.Sub"
reveal_type(sub.one)  # N: Revealed type is "builtins.int"
reveal_type(sub.two)  # N: Revealed type is "builtins.str"
reveal_type(sub.three)  # N: Revealed type is "builtins.float"

[builtins fixtures/dataclasses.pyi]

[case testDataclassMultiGenericInheritance]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar("T")

@dataclass
class Base(Generic[T]):
    base_attr: T

S = TypeVar("S")

@dataclass
class Middle(Base[int], Generic[S]):
    middle_attr: S

@dataclass
class Sub(Middle[str]):
    pass

sub = Sub(base_attr=1, middle_attr='ok')
reveal_type(sub)  # N: Revealed type is "__main__.Sub"
reveal_type(sub.base_attr)  # N: Revealed type is "builtins.int"
reveal_type(sub.middle_attr)  # N: Revealed type is "builtins.str"

[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericsClassmethod]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar('T')

@dataclass
class A(Generic[T]):
  x: T

  @classmethod
  def foo(cls) -> None:
      reveal_type(cls)  # N: Revealed type is "Type[__main__.A[T`1]]"
      cls.x  # E: Access to generic instance variables via class is ambiguous

  @classmethod
  def other(cls, x: T) -> A[T]: ...

reveal_type(A(0).other)  # N: Revealed type is "def (x: builtins.int) -> __main__.A[builtins.int]"
[builtins fixtures/dataclasses.pyi]

[case testDataclassesForwardRefs]
from dataclasses import dataclass

@dataclass
class A:
  b: 'B'

@dataclass
class B:
  x: int

reveal_type(A)  # N: Revealed type is "def (b: __main__.B) -> __main__.A"
A(b=B(42))
A(b=42)  # E: Argument "b" to "A" has incompatible type "int"; expected "B"

[builtins fixtures/dataclasses.pyi]


[case testDataclassesInitVars]
from dataclasses import InitVar, dataclass

@dataclass
class Application:
  name: str
  database_name: InitVar[str]

reveal_type(Application)  # N: Revealed type is "def (name: builtins.str, database_name: builtins.str) -> __main__.Application"
app = Application("example", 42)  # E: Argument 2 to "Application" has incompatible type "int"; expected "str"
app = Application("example", "apps")
app.name
app.database_name  # E: "Application" has no attribute "database_name"


@dataclass
class SpecializedApplication(Application):
  rating: int

reveal_type(SpecializedApplication)  # N: Revealed type is "def (name: builtins.str, database_name: builtins.str, rating: builtins.int) -> __main__.SpecializedApplication"
app = SpecializedApplication("example", "apps", "five")  # E: Argument 3 to "SpecializedApplication" has incompatible type "str"; expected "int"
app = SpecializedApplication("example", "apps", 5)
app.name
app.rating
app.database_name  # E: "SpecializedApplication" has no attribute "database_name"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesInitVarsAndDefer]
from dataclasses import InitVar, dataclass

defer: Yes

@dataclass
class Application:
  name: str
  database_name: InitVar[str]

reveal_type(Application)  # N: Revealed type is "def (name: builtins.str, database_name: builtins.str) -> __main__.Application"
app = Application("example", 42)  # E: Argument 2 to "Application" has incompatible type "int"; expected "str"
app = Application("example", "apps")
app.name
app.database_name  # E: "Application" has no attribute "database_name"

class Yes: ...
[builtins fixtures/dataclasses.pyi]

[case testDataclassesNoInitInitVarInheritance]
from dataclasses import dataclass, field, InitVar

@dataclass
class Super:
    foo: InitVar = field(init=False)

@dataclass
class Sub(Super):
    bar: int

sub = Sub(5)
sub.foo  # E: "Sub" has no attribute "foo"
sub.bar
[builtins fixtures/dataclasses.pyi]

[case testDataclassFactory]
from typing import Type, TypeVar
from dataclasses import dataclass

T = TypeVar('T', bound='A')

@dataclass
class A:
    @classmethod
    def make(cls: Type[T]) -> T:
        reveal_type(cls)  # N: Revealed type is "Type[T`-1]"
        reveal_type(cls())  # N: Revealed type is "T`-1"
        return cls()
[builtins fixtures/dataclasses.pyi]

[case testDataclassesInitVarOverride]
import dataclasses

@dataclasses.dataclass
class A:
    a: dataclasses.InitVar[int]
    _a: int = dataclasses.field(init=False)

    def __post_init__(self, a):
        self._a = a

@dataclasses.dataclass(init=False)
class B(A):
    b: dataclasses.InitVar[int]
    _b: int = dataclasses.field(init=False)

    def __init__(self, b):
        super().__init__(b+1)
        self._b = b

[builtins fixtures/dataclasses.pyi]

[case testDataclassesInitVarNoOverride]
import dataclasses

@dataclasses.dataclass
class A:
    a: dataclasses.InitVar[int]
    _a: int = dataclasses.field(init=False)

    def __post_init__(self, a):
        self._a = a

@dataclasses.dataclass(init=True)
class B(A):
    b: dataclasses.InitVar[int]
    _b: int = dataclasses.field(init=False)

    def __post_init__(self, a, b):
        self._a = a
        self._b = b

B(1, 2)
B(1, 'a') # E: Argument 2 to "B" has incompatible type "str"; expected "int"

[builtins fixtures/dataclasses.pyi]

[case testDataclassesInitVarPostInitOverride]
import dataclasses

@dataclasses.dataclass
class A:
    a: dataclasses.InitVar[int]
    _a: int = dataclasses.field(init=False)

    def __post_init__(self, a: int) -> None:
        self._a = a

@dataclasses.dataclass
class B(A):
    b: int = dataclasses.field(init=False)

    def __post_init__(self, a: int) -> None:
        super().__post_init__(a)
        self.b = a + 1

@dataclasses.dataclass(init=False)
class C(B):
    c: int

    def __init__(self, a: int, c: int) -> None:
        super().__init__(a)
        self.c = c + self.b

A(1)
B(1)
B(1, 2)  # E: Too many arguments for "B"
C(1, 2)
C(1, 'a')  # E: Argument 2 to "C" has incompatible type "str"; expected "int"

[builtins fixtures/primitives.pyi]

[case testDataclassesInitVarIncremental]
import a

[file a.py]
import dataclasses
from b import A

@dataclasses.dataclass
class B(A):
    b: int = dataclasses.field(init=False)

    def __post_init__(self, a: int) -> None:
        super().__post_init__(a)
        self.b = a + 1

[file a.py.2]
import dataclasses
from b import A

@dataclasses.dataclass
class B(A):
    b: int = dataclasses.field(init=False)

    def __post_init__(self, a: int) -> None:
        super().__post_init__(a)
        self.b = a + 2

reveal_type(B)

[file b.py]
import dataclasses

@dataclasses.dataclass
class A:
    a: dataclasses.InitVar[int]
    _a: int = dataclasses.field(init=False)

    def __post_init__(self, a: int) -> None:
        self._a = a
[out2]
tmp/a.py:12: note: Revealed type is "def (a: builtins.int) -> a.B"

[builtins fixtures/primitives.pyi]


[case testNoComplainFieldNone]
# flags: --no-strict-optional
from dataclasses import dataclass, field
from typing import Optional

@dataclass
class Foo:
    bar: Optional[int] = field(default=None)
[builtins fixtures/dataclasses.pyi]
[out]

[case testNoComplainFieldNoneStrict]
from dataclasses import dataclass, field
from typing import Optional

@dataclass
class Foo:
    bar: Optional[int] = field(default=None)
[builtins fixtures/dataclasses.pyi]
[out]

[case testDisallowUntypedWorksForward]
# flags: --disallow-untyped-defs
from dataclasses import dataclass
from typing import List

@dataclass
class B:
    x: C

class C(List[C]):
    pass

reveal_type(B)  # N: Revealed type is "def (x: __main__.C) -> __main__.B"
[builtins fixtures/dataclasses.pyi]

[case testDisallowUntypedWorksForwardBad]
# flags: --disallow-untyped-defs
from dataclasses import dataclass

@dataclass
class B:
    x: Undefined  # E: Name "Undefined" is not defined
    y = undefined()  # E: Name "undefined" is not defined

reveal_type(B)  # N: Revealed type is "def (x: Any) -> __main__.B"
[builtins fixtures/dataclasses.pyi]

[case testMemberExprWorksAsField]
import dataclasses

@dataclasses.dataclass
class A:
    x: int = dataclasses.field(metadata={"doc": "foo"})
    y: str

@dataclasses.dataclass
class B:
    x: int = dataclasses.field(init=False, default=1)
    y: str

@dataclasses.dataclass
class C:
    x: int = dataclasses.field(default=1)
    y: str = dataclasses.field(metadata={"doc": "foo"})  # E: Attributes without a default cannot follow attributes with one
[builtins fixtures/dict.pyi]

[case testDataclassOrderingDeferred]
from dataclasses import dataclass

defer: Yes

@dataclass(order=True)
class Application:
  name: str
  rating: int

a = Application('', 0)
b = Application('', 0)
a < b

class Yes: ...
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldDeferred]
from dataclasses import field, dataclass

@dataclass
class C:
    x: int = field(default=func())

def func() -> int: ...
C('no')  # E: Argument 1 to "C" has incompatible type "str"; expected "int"
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldDeferredFrozen]
from dataclasses import field, dataclass

@dataclass(frozen=True)
class C:
    x: int = field(default=func())

def func() -> int: ...
c: C
c.x = 1  # E: Property "x" defined in "C" is read-only
[builtins fixtures/dataclasses.pyi]

[case testTypeInDataclassDeferredStar]
import lib
[file lib.py]
from dataclasses import dataclass
MYPY = False
if MYPY:  # Force deferral
    from other import *

@dataclass
class C:
    total: int

C()  # E: Missing positional argument "total" in call to "C"
C('no')  # E: Argument 1 to "C" has incompatible type "str"; expected "int"
[file other.py]
import lib
[builtins fixtures/dataclasses.pyi]

[case testDeferredDataclassInitSignature]
# flags: --no-strict-optional
from dataclasses import dataclass
from typing import Optional, Type

@dataclass
class C:
    x: Optional[int] = None
    y: Type[Deferred] = Deferred

    @classmethod
    def default(cls) -> C:
        return cls(x=None, y=None)

class Deferred: pass
[builtins fixtures/dataclasses.pyi]

[case testDeferredDataclassInitSignatureSubclass]
from dataclasses import dataclass
from typing import Optional

@dataclass
class B:
    x: Optional[C]

@dataclass
class C(B):
    y: str

a = C(None, 'abc')
[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaultsIncremental]
import a

[file a.py]
from dataclasses import dataclass
from b import Person

@dataclass
class Asdf(Person):
    c: str = 'test'

[file a.py.2]
from dataclasses import dataclass
from b import Person

@dataclass
class Asdf(Person):
    c: str = 'test'

# asdf

[file b.py]
from dataclasses import dataclass

@dataclass
class Person:
    b: int
    a: str = 'test'

[builtins fixtures/dataclasses.pyi]

[case testDataclassesDefaultsMroOtherFile]
import a

[file a.py]
from dataclasses import dataclass
from b import A1, A2

@dataclass
class Asdf(A1, A2):  # E: Attributes without a default cannot follow attributes with one
    pass

[file b.py]
from dataclasses import dataclass

# a bunch of blank lines to make sure the error doesn't accidentally line up...



@dataclass
class A1:
    a: int

@dataclass
class A2:
    b: str = 'test'

[builtins fixtures/dataclasses.pyi]

[case testDataclassesInheritingDuplicateField]
# see mypy issue #7792
from dataclasses import dataclass

@dataclass
class A:
    x: int = 0
    x: int = 0  # E: Name "x" already defined on line 6

@dataclass
class B(A):
    pass

[builtins fixtures/dataclasses.pyi]

[case testDataclassInheritanceNoAnnotation]
from dataclasses import dataclass

@dataclass
class A:
    foo: int

x = 0
@dataclass
class B(A):
    foo = x

reveal_type(B)  # N: Revealed type is "def (foo: builtins.int) -> __main__.B"

[builtins fixtures/dataclasses.pyi]

[case testDataclassInheritanceNoAnnotation2]
from dataclasses import dataclass

@dataclass(frozen=True)
class A:
    foo: int

@dataclass(frozen=True)
class B(A):
    @property  # E: Dataclass attribute may only be overridden by another attribute
    def foo(self) -> int: pass

reveal_type(B)  # N: Revealed type is "def (foo: builtins.int) -> __main__.B"

[builtins fixtures/dataclasses.pyi]

[case testDataclassHasAttributeWithFields]
from dataclasses import dataclass

@dataclass
class A:
    pass

reveal_type(A.__dataclass_fields__)  # N: Revealed type is "builtins.dict[builtins.str, dataclasses.Field[Any]]"

[builtins fixtures/dict.pyi]

[case testDataclassCallableFieldAccess]
from dataclasses import dataclass
from typing import Callable

@dataclass
class A:
    x: Callable[[int], int]
    y: Callable[[int], int] = lambda i: i

a = A(lambda i:i)
x: int = a.x(0)
y: str = a.y(0) # E: Incompatible types in assignment (expression has type "int", variable has type "str")
reveal_type(a.x)  # N: Revealed type is "def (builtins.int) -> builtins.int"
reveal_type(a.y)  # N: Revealed type is "def (builtins.int) -> builtins.int"
reveal_type(A.y)  # N: Revealed type is "def (builtins.int) -> builtins.int"
[builtins fixtures/dataclasses.pyi]

[case testDataclassCallableFieldAssignment]
from dataclasses import dataclass
from typing import Callable

@dataclass
class A:
    x: Callable[[int], int]

def x(i: int) -> int:
    return i
def x2(s: str) -> str:
    return s

a = A(lambda i:i)
a.x = x
a.x = x2 # E: Incompatible types in assignment (expression has type "Callable[[str], str]", variable has type "Callable[[int], int]")
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldDoesNotFailOnKwargsUnpacking]
# https://github.com/python/mypy/issues/10879
from dataclasses import dataclass, field

@dataclass
class Foo:
    bar: float = field(**{"repr": False})
[out]
main:6: error: Unpacking **kwargs in "field()" is not supported
main:6: error: No overload variant of "field" matches argument type "Dict[str, bool]"
main:6: note: Possible overload variants:
main:6: note:     def [_T] field(*, default: _T, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T
main:6: note:     def [_T] field(*, default_factory: Callable[[], _T], init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T
main:6: note:     def field(*, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> Any
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldWithPositionalArguments]
from dataclasses import dataclass, field

@dataclass
class C:
    x: int = field(0)  # E: "field()" does not accept positional arguments \
                       # E: No overload variant of "field" matches argument type "int" \
                       # N: Possible overload variants: \
                       # N:     def [_T] field(*, default: _T, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T \
                       # N:     def [_T] field(*, default_factory: Callable[[], _T], init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> _T \
                       # N:     def field(*, init: bool = ..., repr: bool = ..., hash: Optional[bool] = ..., compare: bool = ..., metadata: Optional[Mapping[str, Any]] = ..., kw_only: bool = ...) -> Any
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldWithTypedDictUnpacking]
from dataclasses import dataclass, field
from typing import TypedDict

class FieldKwargs(TypedDict):
    repr: bool

field_kwargs: FieldKwargs = {"repr": False}

@dataclass
class Foo:
    bar: float = field(**field_kwargs)  # E: Unpacking **kwargs in "field()" is not supported

reveal_type(Foo(bar=1.5))  # N: Revealed type is "__main__.Foo"
[builtins fixtures/dataclasses.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testDataclassWithSlotsArg]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass(slots=True)
class Some:
    x: int

    def __init__(self, x: int) -> None:
        self.x = x
        self.y = 0  # E: Trying to assign name "y" that is not in "__slots__" of type "__main__.Some"

    def __post_init__(self) -> None:
        self.y = 1  # E: Trying to assign name "y" that is not in "__slots__" of type "__main__.Some"
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithSlotsDef]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass(slots=False)
class Some:
    __slots__ = ('x',)
    x: int

    def __init__(self, x: int) -> None:
        self.x = x
        self.y = 0  # E: Trying to assign name "y" that is not in "__slots__" of type "__main__.Some"

    def __post_init__(self) -> None:
        self.y = 1  # E: Trying to assign name "y" that is not in "__slots__" of type "__main__.Some"
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithSlotsDerivedFromNonSlot]
# flags: --python-version 3.10
from dataclasses import dataclass

class A:
    pass

@dataclass(slots=True)
class B(A):
    x: int

    def __post_init__(self) -> None:
        self.y = 42

[builtins fixtures/dataclasses.pyi]

[case testDataclassWithSlotsConflict]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass(slots=True)
class Some:  # E: "Some" both defines "__slots__" and is used with "slots=True"
    __slots__ = ('x',)
    x: int

@dataclass(slots=True)
class EmptyDef:  # E: "EmptyDef" both defines "__slots__" and is used with "slots=True"
    __slots__ = ()
    x: int

slots = ('x',)

@dataclass(slots=True)
class DynamicDef:  # E: "DynamicDef" both defines "__slots__" and is used with "slots=True"
    __slots__ = slots
    x: int
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithSlotsArgBefore310]
# flags: --python-version 3.9
from dataclasses import dataclass

@dataclass(slots=True)  # E: Keyword argument "slots" for "dataclass" is only valid in Python 3.10 and higher
class Some:
    x: int

# Possible conflict:
@dataclass(slots=True)  # E: Keyword argument "slots" for "dataclass" is only valid in Python 3.10 and higher
class Other:
    __slots__ = ('x',)
    x: int
[builtins fixtures/dataclasses.pyi]


[case testDataclassWithSlotsRuntimeAttr]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass(slots=True)
class Some:
    x: int
    y: str
    z: bool

reveal_type(Some.__slots__)  # N: Revealed type is "Tuple[builtins.str, builtins.str, builtins.str]"

@dataclass(slots=True)
class Other:
    x: int
    y: str

reveal_type(Other.__slots__)  # N: Revealed type is "Tuple[builtins.str, builtins.str]"


@dataclass
class NoSlots:
    x: int
    y: str

NoSlots.__slots__  # E: "Type[NoSlots]" has no attribute "__slots__"
[builtins fixtures/dataclasses.pyi]


[case testSlotsDefinitionWithTwoPasses1]
# flags: --python-version 3.10
# https://github.com/python/mypy/issues/11821
from typing import TypeVar, Protocol, Generic
from dataclasses import dataclass

C = TypeVar("C", bound="Comparable")

class Comparable(Protocol):
    pass

V = TypeVar("V", bound=Comparable)

@dataclass(slots=True)
class Node(Generic[V]):  # Error was here
    data: V
[builtins fixtures/dataclasses.pyi]

[case testSlotsDefinitionWithTwoPasses2]
# flags: --python-version 3.10
from typing import TypeVar, Protocol, Generic
from dataclasses import dataclass

C = TypeVar("C", bound="Comparable")

class Comparable(Protocol):
    pass

V = TypeVar("V", bound=Comparable)

@dataclass(slots=True)  # Explicit slots are still not ok:
class Node(Generic[V]):  # E: "Node" both defines "__slots__" and is used with "slots=True"
    __slots__ = ('data',)
    data: V
[builtins fixtures/dataclasses.pyi]

[case testSlotsDefinitionWithTwoPasses3]
# flags: --python-version 3.10
from typing import TypeVar, Protocol, Generic
from dataclasses import dataclass

C = TypeVar("C", bound="Comparable")

class Comparable(Protocol):
    pass

V = TypeVar("V", bound=Comparable)

@dataclass(slots=True)  # Explicit slots are still not ok, even empty ones:
class Node(Generic[V]):  # E: "Node" both defines "__slots__" and is used with "slots=True"
    __slots__ = ()
    data: V
[builtins fixtures/dataclasses.pyi]

[case testSlotsDefinitionWithTwoPasses4]
# flags: --python-version 3.10
import dataclasses as dtc

PublishedMessagesVar = dict[int, 'PublishedMessages']

@dtc.dataclass(frozen=True, slots=True)
class PublishedMessages:
    left: int
[builtins fixtures/dataclasses.pyi]

[case testDataclassesAnyInherit]
from dataclasses import dataclass
from typing import Any
B: Any
@dataclass
class A(B):
    a: int
@dataclass
class C(B):
    generated_args: int
    generated_kwargs: int

A(a=1, b=2)
A(1)
A(a="foo")  # E: Argument "a" to "A" has incompatible type "str"; expected "int"
C(generated_args="foo", generated_kwargs="bar")  # E: Argument "generated_args" to "C" has incompatible type "str"; expected "int" \
                                                 # E: Argument "generated_kwargs" to "C" has incompatible type "str"; expected "int"
[builtins fixtures/dataclasses.pyi]

[case testDataclassesCallableFrozen]
from dataclasses import dataclass
from typing import Any, Callable
@dataclass(frozen=True)
class A:
    a: Callable[..., None]

def func() -> None:
    pass

reveal_type(A.a)  # N: Revealed type is "def (*Any, **Any)"
A(a=func).a()
A(a=func).a = func  # E: Property "a" defined in "A" is read-only
[builtins fixtures/dataclasses.pyi]

[case testDataclassInFunctionDoesNotCrash]
from dataclasses import dataclass

def foo() -> None:
    @dataclass
    class Foo:
        foo: int
        # This used to crash (see #8703)
        # The return type of __call__ here needs to be something undefined
        # In order to trigger the crash that existed prior to #12762
        def __call__(self) -> asdf: ...  # E: Name "asdf" is not defined
[builtins fixtures/dataclasses.pyi]

[case testDataclassesMultipleInheritanceWithNonDataclass]
# flags: --python-version 3.10
from dataclasses import dataclass

@dataclass
class A:
    prop_a: str

@dataclass
class B:
    prop_b: bool

class Derived(A, B):
    pass
[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericInheritance2]
from dataclasses import dataclass
from typing import Any, Callable, Generic, TypeVar, List

T = TypeVar("T")
S = TypeVar("S")

@dataclass
class Parent(Generic[T]):
    f: Callable[[T], Any]

@dataclass
class Child(Parent[T]): ...

class A: ...
def func(obj: A) -> bool: ...

reveal_type(Child[A](func).f)  # N: Revealed type is "def (__main__.A) -> Any"

@dataclass
class Parent2(Generic[T]):
    a: List[T]

@dataclass
class Child2(Generic[T, S], Parent2[S]):
    b: List[T]

reveal_type(Child2([A()], [1]).a)  # N: Revealed type is "builtins.list[__main__.A]"
reveal_type(Child2[int, A]([A()], [1]).b)  # N: Revealed type is "builtins.list[builtins.int]"
[builtins fixtures/dataclasses.pyi]

[case testDataclassInheritOptionalType]
from dataclasses import dataclass
from typing import Any, Callable, Generic, TypeVar, List, Optional

T = TypeVar("T")

@dataclass
class Parent(Generic[T]):
    x: Optional[str]
@dataclass
class Child(Parent):
    y: Optional[int]
Child(x=1, y=1)  # E: Argument "x" to "Child" has incompatible type "int"; expected "Optional[str]"
Child(x='', y='')  # E: Argument "y" to "Child" has incompatible type "str"; expected "Optional[int]"
Child(x='', y=1)
Child(x=None, y=None)
[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericInheritanceSpecialCase1]
from dataclasses import dataclass
from typing import Generic, TypeVar, List

T = TypeVar("T")

@dataclass
class Parent(Generic[T]):
    x: List[T]

@dataclass
class Child1(Parent["Child2"]): ...

@dataclass
class Child2(Parent["Child1"]): ...

def f(c: Child2) -> None:
    reveal_type(Child1([c]).x)  # N: Revealed type is "builtins.list[__main__.Child2]"

def g(c: Child1) -> None:
    reveal_type(Child2([c]).x)  # N: Revealed type is "builtins.list[__main__.Child1]"
[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericInheritanceSpecialCase2]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar("T")

# A subclass might be analyzed before base in import cycles.  They are
# defined here in reversed order to simulate this.

@dataclass
class Child1(Parent["Child2"]):
    x: int

@dataclass
class Child2(Parent["Child1"]):
    y: int

@dataclass
class Parent(Generic[T]):
    key: str

Child1(x=1, key='')
Child2(y=1, key='')
[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericWithBound]
from dataclasses import dataclass
from typing import Generic, TypeVar

T = TypeVar("T", bound="C")

@dataclass
class C(Generic[T]):
    x: int

c: C[C]
d: C[str]  # E: Type argument "str" of "C" must be a subtype of "C[Any]"
C(x=2)
[builtins fixtures/dataclasses.pyi]

[case testDataclassGenericBoundToInvalidTypeVarDoesNotCrash]
import dataclasses
from typing import Generic, TypeVar

T = TypeVar("T", bound="NotDefined")  # E: Name "NotDefined" is not defined

@dataclasses.dataclass
class C(Generic[T]):
    x: float
[builtins fixtures/dataclasses.pyi]

[case testDataclassInitVarCannotBeSet]
from dataclasses import dataclass, InitVar

@dataclass
class C:
    x: InitVar[int] = 0
    y: InitVar[str] = ''

    def f(self) -> None:
        # This works at runtime, but it seems like an abuse of the InitVar
        # feature and thus we don't support it
        self.x = 1  # E: "C" has no attribute "x"
        self.y: str = 'x'  # E: "C" has no attribute "y"

c = C()
c2 = C(x=1)
c.x  # E: "C" has no attribute "x"
[builtins fixtures/dataclasses.pyi]

[case testDataclassCheckTypeVarBounds]
from dataclasses import dataclass
from typing import ClassVar, Protocol, Dict, TypeVar, Generic

class DataclassProtocol(Protocol):
    __dataclass_fields__: ClassVar[Dict]

T = TypeVar("T", bound=DataclassProtocol)

@dataclass
class MyDataclass:
    x: int = 1

class MyGeneric(Generic[T]): ...
class MyClass(MyGeneric[MyDataclass]): ...
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithMatchArgs]
# flags: --python-version 3.10
from dataclasses import dataclass
@dataclass
class One:
    bar: int
    baz: str
o: One
reveal_type(o.__match_args__)  # N: Revealed type is "Tuple[Literal['bar'], Literal['baz']]"
@dataclass(match_args=True)
class Two:
    bar: int
t: Two
reveal_type(t.__match_args__)  # N: Revealed type is "Tuple[Literal['bar']]"
@dataclass
class Empty:
    ...
e: Empty
reveal_type(e.__match_args__)  # N: Revealed type is "Tuple[()]"
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithoutMatchArgs]
# flags: --python-version 3.10
from dataclasses import dataclass
@dataclass(match_args=False)
class One:
    bar: int
    baz: str
o: One
reveal_type(o.__match_args__)  # E: "One" has no attribute "__match_args__" \
                               # N: Revealed type is "Any"
[builtins fixtures/dataclasses.pyi]

[case testDataclassWithMatchArgsOldVersion]
# flags: --python-version 3.9
from dataclasses import dataclass
@dataclass(match_args=True)
class One:
    bar: int
o: One
reveal_type(o.__match_args__)  # E: "One" has no attribute "__match_args__" \
                               # N: Revealed type is "Any"
@dataclass
class Two:
    bar: int
t: Two
reveal_type(t.__match_args__)  # E: "Two" has no attribute "__match_args__" \
                               # N: Revealed type is "Any"
[builtins fixtures/dataclasses.pyi]

[case testFinalInDataclass]
from dataclasses import dataclass
from typing import Final

@dataclass
class FirstClass:
    FIRST_CONST: Final = 3  # OK

@dataclass
class SecondClass:
    SECOND_CONST: Final = FirstClass.FIRST_CONST  # E: Need type argument for Final[...] with non-literal default in dataclass

reveal_type(FirstClass().FIRST_CONST)  # N: Revealed type is "Literal[3]?"
FirstClass().FIRST_CONST = 42  # E: Cannot assign to final attribute "FIRST_CONST"
reveal_type(SecondClass().SECOND_CONST)  # N: Revealed type is "Literal[3]?"
SecondClass().SECOND_CONST = 42  # E: Cannot assign to final attribute "SECOND_CONST"
[builtins fixtures/dataclasses.pyi]

[case testDataclassFieldsProtocol]
# flags: --python-version 3.9
from dataclasses import dataclass
from typing import Any, Protocol

class ConfigProtocol(Protocol):
    __dataclass_fields__: dict[str, Any]

def takes_cp(cp: ConfigProtocol): ...

@dataclass
class MyDataclass:
    x: int = 3

takes_cp(MyDataclass)
[builtins fixtures/dataclasses.pyi]

[case testDataclassTypeAnnotationAliasUpdated]
import a
[file a.py]
from dataclasses import dataclass
from b import B

@dataclass
class D:
    x: B

reveal_type(D)  # N: Revealed type is "def (x: builtins.list[b.C]) -> a.D"
[file b.py]
from typing import List
import a
class CC: ...
class C(CC): ...
B = List[C]
[builtins fixtures/dataclasses.pyi]

[case testDataclassSelfType]
from dataclasses import dataclass
from typing import Self, TypeVar, Generic, Optional

T = TypeVar("T")

@dataclass
class LinkedList(Generic[T]):
    value: T
    next: Optional[Self] = None

    def meth(self) -> None:
        reveal_type(self.next)  # N: Revealed type is "Union[Self`0, None]"

l_int: LinkedList[int] = LinkedList(1, LinkedList("no", None))  # E: Argument 1 to "LinkedList" has incompatible type "str"; expected "int"

@dataclass
class SubLinkedList(LinkedList[int]): ...

lst = SubLinkedList(1, LinkedList(2))  # E: Argument 2 to "SubLinkedList" has incompatible type "LinkedList[int]"; expected "Optional[SubLinkedList]"
reveal_type(lst.next)  # N: Revealed type is "Union[__main__.SubLinkedList, None]"
reveal_type(SubLinkedList)  # N: Revealed type is "def (value: builtins.int, next: Union[__main__.SubLinkedList, None] =) -> __main__.SubLinkedList"
[builtins fixtures/dataclasses.pyi]

[case testNoCrashOnNestedGenericCallable]
from dataclasses import dataclass
from typing import Generic, TypeVar, Callable

T = TypeVar('T')
R = TypeVar('R')
X = TypeVar('X')

@dataclass
class Box(Generic[T]):
    inner: T

@dataclass
class Cont(Generic[R]):
    run: Box[Callable[[X], R]]

def const_two(x: T) -> str:
    return "two"

c = Cont(Box(const_two))
reveal_type(c)  # N: Revealed type is "__main__.Cont[builtins.str]"
[builtins fixtures/dataclasses.pyi]

[case testNoCrashOnSelfWithForwardRefGenericDataclass]
from typing import Generic, Sequence, TypeVar, Self
from dataclasses import dataclass

_T = TypeVar('_T', bound="Foo")

@dataclass
class Foo:
    foo: int

@dataclass
class Element(Generic[_T]):
    elements: Sequence[Self]

@dataclass
class Bar(Foo): ...
e: Element[Bar]
reveal_type(e.elements)  # N: Revealed type is "typing.Sequence[__main__.Element[__main__.Bar]]"
[builtins fixtures/dataclasses.pyi]

[case testIfConditionsInDefinition]
# flags: --python-version 3.11 --always-true TRUTH
from dataclasses import dataclass
from typing import TYPE_CHECKING

TRUTH = False  # Is set to --always-true

@dataclass
class Foo:
    if TYPE_CHECKING:
        present_1: int
    else:
        skipped_1: int
    if True:  # Mypy does not know if it is True or False, so the block is used
        present_2: int
    if False:  # Mypy does not know if it is True or False, so the block is used
        present_3: int
    if not TRUTH:
        skipped_2: int
    elif 123:
        present_4: int
    elif TRUTH:
        present_5: int
    else:
        skipped_3: int

Foo(
    present_1=1,
    present_2=2,
    present_3=3,
    present_4=4,
    present_5=5,
)

[builtins fixtures/dataclasses.pyi]

[case testReplace]
from dataclasses import dataclass, replace, InitVar
from typing import ClassVar

@dataclass
class A:
    x: int
    q: InitVar[int]
    q2: InitVar[int] = 0
    c: ClassVar[int]


a = A(x=42, q=7)
a2 = replace(a)  # E: Missing named argument "q" for "replace" of "A"
a2 = replace(a, q=42)
a2 = replace(a, x=42, q=42)
a2 = replace(a, x=42, q=42, c=7)  # E: Unexpected keyword argument "c" for "replace" of "A"
a2 = replace(a, x='42', q=42)  # E: Argument "x" to "replace" of "A" has incompatible type "str"; expected "int"
a2 = replace(a, q='42')  # E: Argument "q" to "replace" of "A" has incompatible type "str"; expected "int"
reveal_type(a2)  # N: Revealed type is "__main__.A"

[builtins fixtures/tuple.pyi]

[case testReplaceUnion]
from typing import Generic, Union, TypeVar
from dataclasses import dataclass, replace, InitVar

T = TypeVar('T')

@dataclass
class A(Generic[T]):
    x: T  # exercises meet(T=int, int) = int
    y: bool  # exercises meet(bool, int) = bool
    z: str  # exercises meet(str, bytes) = Never
    w: dict  # exercises meet(dict, Never) = Never
    init_var: InitVar[int]  # exercises (non-optional, optional) = non-optional

@dataclass
class B:
    x: int
    y: int
    z: bytes
    init_var: int


a_or_b: Union[A[int], B]
_ = replace(a_or_b, x=42, y=True, init_var=42)
_ = replace(a_or_b, x=42, y=True)  # E: Missing named argument "init_var" for "replace" of "Union[A[int], B]"
_ = replace(a_or_b, x=42, y=True, z='42', init_var=42)  # E: Argument "z" to "replace" of "Union[A[int], B]" has incompatible type "str"; expected "Never"
_ = replace(a_or_b, x=42, y=True, w={}, init_var=42)  # E: Argument "w" to "replace" of "Union[A[int], B]" has incompatible type "Dict[Never, Never]"; expected "Never"
_ = replace(a_or_b, y=42, init_var=42)  # E: Argument "y" to "replace" of "Union[A[int], B]" has incompatible type "int"; expected "bool"

[builtins fixtures/tuple.pyi]

[case testReplaceUnionOfTypeVar]
from typing import Generic, Union, TypeVar
from dataclasses import dataclass, replace

@dataclass
class A:
    x: int
    y: int
    z: str
    w: dict

class B:
    pass

TA = TypeVar('TA', bound=A)
TB = TypeVar('TB', bound=B)

def f(b_or_t: Union[TA, TB, int]) -> None:
    a2 = replace(b_or_t)   # E: Value of type variable "_DataclassT" of "replace" cannot be "Union[TA, TB, int]"

[builtins fixtures/tuple.pyi]

[case testReplaceTypeVarBoundNotDataclass]
from dataclasses import dataclass, replace
from typing import Union, TypeVar

TInt = TypeVar('TInt', bound=int)
TAny = TypeVar('TAny')
TNone = TypeVar('TNone', bound=None)
TUnion = TypeVar('TUnion', bound=Union[str, int])

def f1(t: TInt) -> None:
    _ = replace(t, x=42)  # E: Value of type variable "_DataclassT" of "replace" cannot be "TInt"

def f2(t: TAny) -> TAny:
    return replace(t, x='spam')  # E: Value of type variable "_DataclassT" of "replace" cannot be "TAny"

def f3(t: TNone) -> TNone:
    return replace(t, x='spam')  # E: Value of type variable "_DataclassT" of "replace" cannot be "TNone"

def f4(t: TUnion) -> TUnion:
    return replace(t, x='spam')  # E: Value of type variable "_DataclassT" of "replace" cannot be "TUnion"

[builtins fixtures/tuple.pyi]

[case testReplaceTypeVarBound]
from dataclasses import dataclass, replace
from typing import TypeVar

@dataclass
class A:
    x: int

@dataclass
class B(A):
    pass

TA = TypeVar('TA', bound=A)

def f(t: TA) -> TA:
    t2 = replace(t, x=42)
    reveal_type(t2)  # N: Revealed type is "TA`-1"
    _ = replace(t, x='42')  # E: Argument "x" to "replace" of "TA" has incompatible type "str"; expected "int"
    return t2

f(A(x=42))
f(B(x=42))

[builtins fixtures/tuple.pyi]

[case testReplaceAny]
from dataclasses import replace
from typing import Any

a: Any
a2 = replace(a)
reveal_type(a2)  # N: Revealed type is "Any"

[builtins fixtures/tuple.pyi]

[case testReplaceNotDataclass]
from dataclasses import replace

replace(5)  # E: Value of type variable "_DataclassT" of "replace" cannot be "int"

class C:
    pass

replace(C())  # E: Value of type variable "_DataclassT" of "replace" cannot be "C"

replace(None)  # E: Value of type variable "_DataclassT" of "replace" cannot be "None"

[builtins fixtures/tuple.pyi]

[case testReplaceIsDataclass]
from dataclasses import is_dataclass, replace

def f(x: object) -> None:
  _ = replace(x)  # E: Value of type variable "_DataclassT" of "replace" cannot be "object"
  if is_dataclass(x):
    _ = replace(x)  # E: Value of type variable "_DataclassT" of "replace" cannot be "Union[DataclassInstance, Type[DataclassInstance]]"
    if not isinstance(x, type):
      _ = replace(x)

[builtins fixtures/tuple.pyi]

[case testReplaceGeneric]
from dataclasses import dataclass, replace, InitVar
from typing import ClassVar, Generic, TypeVar

T = TypeVar('T')

@dataclass
class A(Generic[T]):
    x: T

a = A(x=42)
reveal_type(a)  # N: Revealed type is "__main__.A[builtins.int]"
a2 = replace(a, x=42)
reveal_type(a2)  # N: Revealed type is "__main__.A[builtins.int]"
a2 = replace(a, x='42')  # E: Argument "x" to "replace" of "A[int]" has incompatible type "str"; expected "int"
reveal_type(a2)  # N: Revealed type is "__main__.A[builtins.int]"

[builtins fixtures/tuple.pyi]

[case testPostInitNotMethod]
def __post_init__() -> None:
    pass

[case testPostInitCorrectSignature]
from typing import Any, Generic, TypeVar, Callable, Self
from dataclasses import dataclass, InitVar

@dataclass
class Test1:
    x: int
    def __post_init__(self) -> None: ...

@dataclass
class Test2:
    x: int
    y: InitVar[int]
    z: str
    def __post_init__(self, y: int) -> None: ...

@dataclass
class Test3:
    x: InitVar[int]
    y: InitVar[str]
    def __post_init__(self, x: int, y: str) -> None: ...

@dataclass
class Test4:
    x: int
    y: InitVar[str]
    z: InitVar[bool] = True
    def __post_init__(self, y: str, z: bool) -> None: ...

@dataclass
class Test5:
    y: InitVar[str] = 'a'
    z: InitVar[bool] = True
    def __post_init__(self, y: str = 'a', z: bool = True) -> None: ...

F = TypeVar('F', bound=Callable[..., Any])
def identity(f: F) -> F: return f

@dataclass
class Test6:
    y: InitVar[str]
    @identity  # decorated method works
    def __post_init__(self, y: str) -> None: ...

T = TypeVar('T')

@dataclass
class Test7(Generic[T]):
    t: InitVar[T]
    def __post_init__(self, t: T) -> None: ...

@dataclass
class Test8:
    s: InitVar[Self]
    def __post_init__(self, s: Self) -> None: ...
[builtins fixtures/dataclasses.pyi]

[case testPostInitSubclassing]
from dataclasses import dataclass, InitVar

@dataclass
class Base:
    a: str
    x: InitVar[int]
    def __post_init__(self, x: int) -> None: ...

@dataclass
class Child(Base):
    b: str
    y: InitVar[str]
    def __post_init__(self, x: int, y: str) -> None: ...

@dataclass
class GrandChild(Child):
    c: int
    z: InitVar[str] = "a"
    def __post_init__(self, x: int, y: str, z: str) -> None: ...
[builtins fixtures/dataclasses.pyi]

[case testPostInitNotADataclassCheck]
from dataclasses import dataclass, InitVar

class Regular:
    __post_init__ = 1  # can be whatever

class Base:
    x: InitVar[int]
    def __post_init__(self) -> None: ...  # can be whatever

@dataclass
class Child(Base):
    y: InitVar[str]
    def __post_init__(self, y: str) -> None: ...
[builtins fixtures/dataclasses.pyi]

[case testPostInitMissingParam]
from dataclasses import dataclass, InitVar

@dataclass
class Child:
    y: InitVar[str]
    def __post_init__(self) -> None: ...
[builtins fixtures/dataclasses.pyi]
[out]
main:6: error: Signature of "__post_init__" incompatible with supertype "dataclass"
main:6: note:      Superclass:
main:6: note:          def __post_init__(self: Child, y: str) -> None
main:6: note:      Subclass:
main:6: note:          def __post_init__(self: Child) -> None

[case testPostInitWrongTypeAndName]
from dataclasses import dataclass, InitVar

@dataclass
class Test1:
    y: InitVar[str]
    def __post_init__(self, x: int) -> None: ...  # E: Argument 2 of "__post_init__" is incompatible with supertype "dataclass"; supertype defines the argument type as "str"

@dataclass
class Test2:
    y: InitVar[str] = 'a'
    def __post_init__(self, x: int) -> None: ...  # E: Argument 2 of "__post_init__" is incompatible with supertype "dataclass"; supertype defines the argument type as "str"
[builtins fixtures/dataclasses.pyi]

[case testPostInitExtraParam]
from dataclasses import dataclass, InitVar

@dataclass
class Child:
    y: InitVar[str]
    def __post_init__(self, y: str, z: int) -> None: ...
[builtins fixtures/dataclasses.pyi]
[out]
main:6: error: Signature of "__post_init__" incompatible with supertype "dataclass"
main:6: note:      Superclass:
main:6: note:          def __post_init__(self: Child, y: str) -> None
main:6: note:      Subclass:
main:6: note:          def __post_init__(self: Child, y: str, z: int) -> None

[case testPostInitReturnType]
from dataclasses import dataclass, InitVar

@dataclass
class Child:
    y: InitVar[str]
    def __post_init__(self, y: str) -> int: ...  # E: Return type "int" of "__post_init__" incompatible with return type "None" in supertype "dataclass"
[builtins fixtures/dataclasses.pyi]

[case testPostInitDecoratedMethodError]
from dataclasses import dataclass, InitVar
from typing import Any, Callable, TypeVar

F = TypeVar('F', bound=Callable[..., Any])
def identity(f: F) -> F: return f

@dataclass
class Klass:
    y: InitVar[str]
    @identity
    def __post_init__(self) -> None: ...
[builtins fixtures/dataclasses.pyi]
[out]
main:11: error: Signature of "__post_init__" incompatible with supertype "dataclass"
main:11: note:      Superclass:
main:11: note:          def __post_init__(self: Klass, y: str) -> None
main:11: note:      Subclass:
main:11: note:          def __post_init__(self: Klass) -> None

[case testPostInitIsNotAFunction]
from dataclasses import dataclass, InitVar

@dataclass
class Test:
    y: InitVar[str]
    __post_init__ = 1  # E: "__post_init__" method must be an instance method
[builtins fixtures/dataclasses.pyi]

[case testPostInitClassMethod]
from dataclasses import dataclass, InitVar

@dataclass
class Test:
    y: InitVar[str]
    @classmethod
    def __post_init__(cls) -> None: ...
[builtins fixtures/dataclasses.pyi]
[out]
main:7: error: Signature of "__post_init__" incompatible with supertype "dataclass"
main:7: note:      Superclass:
main:7: note:          def __post_init__(self: Test, y: str) -> None
main:7: note:      Subclass:
main:7: note:          @classmethod
main:7: note:          def __post_init__(cls: Type[Test]) -> None

[case testPostInitStaticMethod]
from dataclasses import dataclass, InitVar

@dataclass
class Test:
    y: InitVar[str]
    @staticmethod
    def __post_init__() -> None: ...
[builtins fixtures/dataclasses.pyi]
[out]
main:7: error: Signature of "__post_init__" incompatible with supertype "dataclass"
main:7: note:      Superclass:
main:7: note:          def __post_init__(self: Test, y: str) -> None
main:7: note:      Subclass:
main:7: note:          @staticmethod
main:7: note:          def __post_init__() -> None

[case testProtocolNoCrash]
from typing import Protocol, Union, ClassVar
from dataclasses import dataclass, field

DEFAULT = 0

@dataclass
class Test(Protocol):
    x: int
    def reset(self) -> None:
        self.x = DEFAULT
[builtins fixtures/dataclasses.pyi]

[case testProtocolNoCrashOnJoining]
from dataclasses import dataclass
from typing import Protocol

@dataclass
class MyDataclass(Protocol): ...

a: MyDataclass
b = [a, a]  # trigger joining the types

[builtins fixtures/dataclasses.pyi]

[case testPropertyAndFieldRedefinitionNoCrash]
from dataclasses import dataclass

@dataclass
class Foo:
    @property
    def c(self) -> int:
        return 0

    c: int  # E: Name "c" already defined on line 5
[builtins fixtures/dataclasses.pyi]

[case testDataclassInheritanceWorksWithExplicitOverrides]
# flags: --enable-error-code explicit-override
from dataclasses  import dataclass

@dataclass
class Base:
    x: int

@dataclass
class Child(Base):
    y: int
[builtins fixtures/dataclasses.pyi]


[case testDataclassInheritanceWorksWithExplicitOverridesAndOrdering]
# flags: --enable-error-code explicit-override
from dataclasses import dataclass

@dataclass(order=True)
class Base:
    x: int

@dataclass(order=True)
class Child(Base):
    y: int
[builtins fixtures/dataclasses.pyi]

[case testDunderReplacePresent]
# flags: --python-version 3.13
from dataclasses import dataclass, field

@dataclass
class Coords:
    x: int
    y: int
    # non-init fields are not allowed with replace:
    z: int = field(init=False)


replaced = Coords(2, 4).__replace__(x=2, y=5)
reveal_type(replaced)  # N: Revealed type is "__main__.Coords"

replaced = Coords(2, 4).__replace__(x=2)
reveal_type(replaced)  # N: Revealed type is "__main__.Coords"

Coords(2, 4).__replace__(x="asdf")  # E: Argument "x" to "__replace__" of "Coords" has incompatible type "str"; expected "int"
Coords(2, 4).__replace__(23)          # E: Too many positional arguments for "__replace__" of "Coords"
Coords(2, 4).__replace__(23, 25)      # E: Too many positional arguments for "__replace__" of "Coords"
Coords(2, 4).__replace__(x=23, y=25, z=42)  # E: Unexpected keyword argument "z" for "__replace__" of "Coords"

from typing import Generic, TypeVar
T = TypeVar('T')

@dataclass
class Gen(Generic[T]):
    x: T

replaced_2 = Gen(2).__replace__(x=2)
reveal_type(replaced_2)  # N: Revealed type is "__main__.Gen[builtins.int]"
Gen(2).__replace__(x="not an int")  # E: Argument "x" to "__replace__" of "Gen" has incompatible type "str"; expected "int"

[builtins fixtures/tuple.pyi]

[case testDunderReplaceCovariantOverride]
# flags: --python-version 3.13  --enable-error-code mutable-override
from dataclasses import dataclass
from typing import Optional
from typing_extensions import dataclass_transform

@dataclass
class Base:
    a: Optional[int]

@dataclass
class Child(Base):
    a: int  # E: Covariant override of a mutable attribute (base class "Base" defined the type as "Optional[int]", expression has type "int")

@dataclass
class Other(Base):
    a: str  # E: Incompatible types in assignment (expression has type "str", base class "Base" defined the type as "Optional[int]")

@dataclass_transform(kw_only_default=True)
class DCMeta(type): ...

class X(metaclass=DCMeta):
    a: Optional[int]

class Y(X):
    a: int  # E: Covariant override of a mutable attribute (base class "X" defined the type as "Optional[int]", expression has type "int")
[builtins fixtures/tuple.pyi]


[case testFrozenWithFinal]
from dataclasses import dataclass
from typing import Final

@dataclass(frozen=True)
class My:
    a: Final = 1
    b: Final[int] = 2

reveal_type(My.a)  # N: Revealed type is "Literal[1]?"
reveal_type(My.b)  # N: Revealed type is "builtins.int"
My.a = 1  # E: Cannot assign to final attribute "a"
My.b = 2  # E: Cannot assign to final attribute "b"

m = My()
reveal_type(m.a)  # N: Revealed type is "Literal[1]?"
reveal_type(m.b)  # N: Revealed type is "builtins.int"

m.a = 1  # E: Cannot assign to final attribute "a"
m.b = 2  # E: Cannot assign to final attribute "b"
[builtins fixtures/tuple.pyi]

[case testNoCrashForDataclassNamedTupleCombination]
# flags: --python-version 3.13
from dataclasses import dataclass
from typing import NamedTuple

@dataclass
class A(NamedTuple):  # E: A NamedTuple cannot be a dataclass
    i: int

class B1(NamedTuple):
    i: int
@dataclass
class B2(B1):  # E: A NamedTuple cannot be a dataclass
    pass

[builtins fixtures/tuple.pyi]